Cardiac Arrest Management & ACLS Guide

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Questions and Answers

In post-ROSC care, what is the oxygenation target, and why is it important to avoid hyperoxia?

Titrate FiO2 to SpO2 ≥94%, Avoid PaO2 >300 mmHg to prevent oxygen toxicity.

What are the two first-line antiarrhythmics given in the setting of refractory VF/pVT and what are their initial doses?

Amiodarone (300mg IV/IO first dose), Lidocaine (1-1.5 mg/kg first dose)

Describe how end-tidal CO2 (ETCO2) is used to assess the effectiveness of CPR and predict ROSC.

ETCO2 <10 mm Hg indicates ineffective CPR; a sudden rise from <10 mmHg to >40 mmHg suggests ROSC.

List three dynamic measures that can be used to assess volume responsiveness in a post-arrest patient.

<p>IVC collapse, Passive leg raise, Pulse pressure variation</p> Signup and view all the answers

What is the preferred vasopressor and its infusion rate for pseudo-PEA?

<p>Norepinephrine infusion (0.1-0.5 mcg/kg/min)</p> Signup and view all the answers

What are three contraindications to initiating hypothermia therapy in a patient after cardiac arrest?

<p>Active bleeding, DNR status, Terminal illness (relative)</p> Signup and view all the answers

What are the three components of the mnemonic "ABCs of ROSC" for post-arrest care priorities?

<p>A - ACS evaluation, B - BP management, C - Cooling/TTM, S - Seizure prevention</p> Signup and view all the answers

List three complications related to ECPR.

<p>Limb ischemia, Hemorrhage, Renal failure requiring RRT</p> Signup and view all the answers

What is the timeframe for lactate clearance monitoring post-arrest, and why is monitoring lactate trends important?

<p>Q2-4h initially (decrease &gt;10%/hour). Decreasing serial levels indicate improving perfusion.</p> Signup and view all the answers

  1. What is the significance of a 3rd-degree or new bifascicular block on ECG in a post-ROSC patient, and what intervention should be considered?

<p>Requires transcutaneous pacing</p> Signup and view all the answers

What is the sodium bicarbonate dose for a TCA overdose?

<p>1-2 mEq/kg IV</p> Signup and view all the answers

When is immediate PCI indicated in a patient post-ROSC?

<p>STEMI on ECG or suspicion of ACS without non-cardiac cause.</p> Signup and view all the answers

Why is dobutamine contraindicated in HOCM?

<p>↑ Contractility → worsens obstruction → collapse.</p> Signup and view all the answers

Outline three parameters to monitor for CPR quality.

<p>Rate (100-120/min), Depth (2-2.4&quot;), Recoil (complete)</p> Signup and view all the answers

Describe the permissive hypertension strategy post-ROSC including the target blood pressure.

<p>Permissive hypertension initially (MAP 65-90mmHg)</p> Signup and view all the answers

What is the dextrose dose for treating hypoglycemia in an arrest situation?

<p>25-50g IV (D50W standard).</p> Signup and view all the answers

What is the preferred beta blocker in labile post-arrest patients, and why is it preferred?

<p>Esmolol drip (short-acting, titratable).</p> Signup and view all the answers

How long should therapeutic hypothermia be maintained after reaching the target temperature?

<p>24 hours minimum before rewarming.</p> Signup and view all the answers

What ultrasound finding is diagnostic for pseudo-PEA?

<p>Cardiac activity on echo without palpable pulses.</p> Signup and view all the answers

What is the post-ROSC ScvO2 goal?

<blockquote> <p>65% (adequate oxygen delivery).</p> </blockquote> Signup and view all the answers

What is a key target CPP value during CPR and what pressures are used to calculate CPP?

<p>Minimum 15-20 mmHg (aortic diastolic - right atrial pressure).</p> Signup and view all the answers

What are three symptoms of HOCM?

<p>Chest pain, Syncope, Sudden cardiac death (arrhythmias).</p> Signup and view all the answers

What are the three HTTM target temperature parameters?

<p>32-36°C, Maintained for 24 hours, Rewarm at 0.5°C/hour.</p> Signup and view all the answers

What Scv02 value predicts no ROSC during CPR?

<p>&lt;40% (100% negative predictive value).</p> Signup and view all the answers

What is the mnemonic for epinephrine dosing?

<p>&quot;1-3-5 Rule&quot;: 1 mg every 3-5 minutes during CPR.</p> Signup and view all the answers

What is the mnemonic for calcium doses?

<p>&quot;1-3 Rule&quot;: 1g chloride or 3g gluconate.</p> Signup and view all the answers

What is the mnemonic for HOCM risks?

<p>&quot;HOCM&quot;: Heart Obstructed Contractility Kills Muscle → avoid inotropes.</p> Signup and view all the answers

What is the first-line treatment (drug class) for Hypertrophic Obstructive Cardiomyopathy (HOCM)?

<p>Beta-blockers (e.g., metoprolol) or non-DHP calcium channel blockers.</p> Signup and view all the answers

What is the vasopressor and dose for cardiac arrest?

<p>Epinephrine 1 mg IV/IO every 3-5 minutes or Vassopressin 40 units IV push (alternative).</p> Signup and view all the answers

What are the first-line benzodiazepine doses for post-arrest seizures?

<p>Lorazepam 0.1 mg/kg IV (max 4mg)or midazolam 0.2 mg/kg IM (max 10mg).</p> Signup and view all the answers

What is the post-ROSC anticoagulation caution during CPR?

<p>Monitor for CPR-related injuries (rib fractures, liver/spleen trauma).</p> Signup and view all the answers

What is the absolute contraindication for fibrinolytics post-ROSC?

<p>CPR-related trauma (e.g., pneumothorax/pulmonary hemorrhage).</p> Signup and view all the answers

What should you monitor for any patient who has undergone ECPR?

<p>Limb ischemia (femoral cannulation).</p> Signup and view all the answers

What should you see on EtCO2 used when needle decompression of tension pneumothorax?

<p>Rise after needle decompression confirms success.</p> Signup and view all the answers

What are the three predictors of poor neurologic outcome?

<p>No pupillary/corneal reflexes at 72h, Myoclonus status, or NSE &gt;60ng/mL. (Pupillary/corneal reflexes assesses brainstem functions. Myoclonus involves sporadic involuntary twitches. NSE greater than 60 nanograms/ml indicates damage to neurons.)</p> Signup and view all the answers

What key information is provided by an echocardiogram for someone with HOCM?

<p>Echocardiogram (asymmetric septal hypertrophy + outflow gradient).</p> Signup and view all the answers

What do you do if youre managing post-ROSC hypertension?

<p>Permissive hypertension initially (MAP 65-90mmHg).</p> Signup and view all the answers

What post-ROSC anticoagulation is administered for ACS?

<p>Dual antiplatelets: aspirin + ticagrelor (preferred over clopidogrel).</p> Signup and view all the answers

When do you begin implementing PCI timing with HTTM?

<p>Proceed immediately - don't delay cooling.</p> Signup and view all the answers

What is the genetic pattern of HOCM?

<p>Autosomal dominant (MYH7/MYBPC3 mutations).</p> Signup and view all the answers

Explain the rationale for permissive hypertension in the immediate post-ROSC period, including the target MAP range.

<p>Permissive hypertension (MAP 65-90 mmHg) balances the need for adequate cerebral perfusion with the risk of exacerbating bleeding or cardiac dysfunction. It allows for a higher blood pressure to overcome potential vasoconstriction or edema while avoiding excessive strain on the heart.</p> Signup and view all the answers

Describe the '1-3-5 Rule' in the context of cardiac arrest management. Include the medications, dosages and frequency.

<p>1 mg Epinephrine every 3-5 minutes during CPR. For calcium dosing, administer 1g Calcium Chloride IV or 3g Calcium Gluconate</p> Signup and view all the answers

How does the physiological mechanism of dynamic left ventricular outflow tract obstruction in Hypertrophic Obstructive Cardiomyopathy (HOCM) contraindicate the use of dobutamine?

<p>Dobutamine increases myocardial contractility, which can worsen the outflow obstruction in HOCM, leading to reduced cardiac output and potential collapse. The increased contractility exacerbates the narrowing of the outflow tract.</p> Signup and view all the answers

Outline three key differences in post-ROSC care for a patient who had a witnessed arrest with bystander CPR and initial shockable rhythm, compared to a patient without these factors, justifying each difference.

<ol> <li>ECPR candidacy: Witnessed arrest, bystander CPR, and initial shockable rhythm are all ECPR candidate criteria. 2. EEG Monitoring Duration: Post-arrest EEG monitoring duration should be at least 24-48h since 20% have delayed seizures. 3. PCI Timing w/ HTTM: proceed immediately - don't delay cooling.</li> </ol> Signup and view all the answers

Explain the significance of monitoring limb ischemia as a potential complication of ECPR (Extracorporeal Cardiopulmonary Resuscitation) involving femoral cannulation.

<p>Femoral cannulation during ECPR can compromise blood flow to the leg, leading to limb ischemia. Monitoring is crucial to detect early signs of ischemia (e.g., pain, pallor, pulselessness, paresthesia, paralysis), allowing for timely intervention to prevent irreversible damage or amputation.</p> Signup and view all the answers

What hemodynamic parameters are targeted when titrating chest compressions and vasopressor therapy during CPR, according to animal models?

<p>Systolic blood pressure of 90 mm Hg and a coronary perfusion pressure (CPP) of 20 mm Hg.</p> Signup and view all the answers

During CPR, how is coronary perfusion pressure (CPP) defined, and why is its measurement challenging in most ED resuscitations?

<p>CPP is defined as the difference between aortic and right atrial pressures during relaxation (CPR diastole). It is challenging to measure because it requires placement of both arterial and central venous catheters, which is often impractical in emergency scenarios.</p> Signup and view all the answers

In the context of VF or pVT refractory to defibrillation, what anti-arrhythmic drugs are recommended as first-line agents, and what are their initial dosages?

<p>Amiodarone (300 mg IV/IO) or lidocaine (1 to 1.5 mg/kg IV/IO) are recommended.</p> Signup and view all the answers

Beyond bradycardia, when is the administration of atropine considered beneficial according to this text?

<p>Routine administration of atropine outside the setting of bradycardia is not beneficial.</p> Signup and view all the answers

Besides CPR performance parameters, what specific physiologic monitoring techniques can help optimize CPR quality for an individual patient?

<p>CPP, end-tidal carbon dioxide (ETco2), and central venous oxygen saturation (Scvo2) monitoring.</p> Signup and view all the answers

Why does electrocardiographic (ECG) monitoring have limitations during cardiac arrest?

<p>ECG monitoring indicates the presence or absence of electrical activity but not mechanical activity.</p> Signup and view all the answers

How does end-tidal carbon dioxide (PETco2) monitoring provide insights into cardiac output during CPR, and what is its clinical significance?

<p>PETco2 correlates well with CPP and cerebral perfusion pressure during CPR. Increased cardiac output during CPR will significantly increase PETco2, when minute ventilation is held constant and no exogenous CO2 is introduced.</p> Signup and view all the answers

During CPR, what PETco2 value should prompt clinicians to enhance the quality of CPR?

<p>PETco2 values less than 10 mm Hg.</p> Signup and view all the answers

How can PETco2 monitoring aid in the diagnosis and treatment of PEA (Pulseless Electrical Activity)?

<p>Elevated PETco2 levels in PEA may indicate mechanical heart activity, suggesting pulsatile flow undetectable by pulse palpation. This indicates the need for volume expansion or use of vasopressors and inotropes.</p> Signup and view all the answers

What is the significance of central venous oxygen saturation (Scvo2) monitoring during CPR, and how does it reflect oxygen delivery to tissues?

<p>Changes in Scvo2 reflect changes in oxygen delivery by means of changes in cardiac output, because oxygen consumption remains relatively constant during CPR, as does arterial oxygen saturation (Sao2) and hemoglobin.</p> Signup and view all the answers

What Scvo2 value during CPR has a negative predictive value for ROSC of almost 100%?

<p>Failure to achieve an Scvo2 of 40% or greater during CPR.</p> Signup and view all the answers

How does echocardiography aid in the diagnosis and management of cardiac arrest?

<p>Echocardiography helps distinguish EMD from pseudo-EMD, diagnose mechanical causes of PEA, and guide pericardiocentesis. In the post-arrest period it evaluates myocardial dysfunction to determine need for mechanical assistance of the failing heart.</p> Signup and view all the answers

What are the key factors for successful implementation of ECPR (Extracorporeal Cardiopulmonary Resuscitation) for refractory OHCA (Out-of-Hospital Cardiac Arrest)?

<p>Timely arterial and venous access, placement of cannulas, and initiation of ECPR support within 60 minutes of cardiac arrest onset.</p> Signup and view all the answers

Besides Scvo2, what other laboratory findings are typically observed during CPR, and how do they influence resuscitation therapy?

<p>Typical blood gas findings during CPR demonstrate venous respiratory acidosis and arterial respiratory alkalosis. Sao2 is usually greater than 94% during CPR and is of little value in titrating resuscitation therapy, except in the case of massive pulmonary embolism or unrecognized esophageal intubation.</p> Signup and view all the answers

While titrating resuscitation efforts to arterial relaxation (diastolic) pressure can be helpful, it also has limitations. Explain why.

<p>Improper CPR (e.g., leaning on the chest during CPR diastole and hyperventilation) can cause undetected elevations in the right atrial pressure, reducing coronary perfusion.</p> Signup and view all the answers

What is the significance of arterial and central venous catheter placement during the post-cardiac arrest phase of care, especially considering the risk of re-arrest?

<p>10% to 20% of patients initially achieving ROSC will re-arrest, making these modalities helpful during the patient’s subsequent resuscitation.</p> Signup and view all the answers

What are the two primary goals of management following ROSC (Return of Spontaneous Circulation) in a cardiac arrest victim?

<p>Rapid diagnosis and treatment of the disorders that caused the arrest and complications of prolonged global ischemia.</p> Signup and view all the answers

What specific inclusion criteria were used in the studies that showed improved survival and functional outcome with Hypothermic Targeted Temperature Management (HTTM)?

<p>These studies enrolled only comatose survivors of OHCA that were witnessed arrests and had an initial rhythm of VF.</p> Signup and view all the answers

Epinephrine is recommended during resuscitation. Detail the rationale behind its use, including the recommended dosage and frequency of administration.

<p>Epinephrine at 1 mg every 3 to 5 minutes is recommended to due improved survival and ROSC demonstrated in randomized clinical trials.</p> Signup and view all the answers

Discuss the advantages, if any, of using vasopressin as a substitute for epinephrine in cardiac arrest scenarios, considering the evidence presented.

<p>Vasopressin offers no advantage as a substitute for epinephrine in cardiac arrest.</p> Signup and view all the answers

Explain the physiological basis behind targeting an arterial relaxation pressure of at least 20 to 25 mm Hg during CPR, and why this is important for patient outcomes.

<p>Titrating vasopressors to an arterial relaxation pressure of at least 20 to 25 mm Hg supports the recommendation of CPP of 20 mm Hg, which demonstrated improved outcomes in animal models.</p> Signup and view all the answers

In cases of VF or pVT refractory to defibrillation, amiodarone and lidocaine are recommended. Summarize the comparative effectiveness of these two drugs based on recent clinical trials.

<p>Only lidocaine resulted in an increased rate of ROSC, although neither therapy resulted in statistically significant improvements in survival.</p> Signup and view all the answers

Describe specific clinical scenarios, beyond electrolyte imbalances, where the administration of magnesium sulfate, calcium, sodium bicarbonate, or dextrose may be warranted during resuscitation.

<p>Magnesium sulfate in torsades de pointes, calcium in hyperkalemia, sodium bicarbonate in tricyclic antidepressant overdose, and dextrose in hypoglycemia.</p> Signup and view all the answers

What are the limitations of relying solely on palpation of carotid or femoral artery pulses for monitoring during CPR, and why is it considered unreliable?

<p>Myocardial blood flow does not depend on the palpated arterial pressure during chest compression (CPR systole), but rather on CPP. Although these two monitoring modalities may be the best attainable in certain circumstances, they do not provide reliable information regarding the effectiveness of CPR and interventions or prognosis.</p> Signup and view all the answers

Explain the relationship between PETco2, CO2 production, alveolar ventilation, and pulmonary blood flow during CPR and how changes in these parameters can inform clinical decision-making.

<p>PETco2 depends on CO2 production, alveolar ventilation, and pulmonary blood flow (i.e., cardiac output) and correlates well with CPP and cerebral perfusion pressure during CPR. When minute ventilation is held constant and no exogenous CO2 is introduced only increased cardiac output during CPR will significantly increase PETco2.</p> Signup and view all the answers

Discuss the clinical implications of using PETco2 monitoring to detect ROSC at any time during the chest compression cycle, and why this is advantageous over traditional pulse checks.

<p>ROSC causes immediate and significant increases in PETco2. Therefore, PETco2 monitoring can detect ROSC at any time during the chest compression cycle, providing valuable guidance for pharmacologic therapies and minimizing the need for a pulse check when organized rhythms are detected.</p> Signup and view all the answers

In the context of PEA, how can PETco2 monitoring differentiate between true PEA and pseudo-PEA, and what are the corresponding treatment implications?

<p>Patients in a state of PEA with mechanical heart activity may have pulsatile flow that simply cannot be detected by palpation of a pulse. In such cases, PETco2 levels may be elevated, even without compressions. Use of ultrasound in such cases can identify corresponding cardiac activity. In these cases, volume expansion or the use of vasopressors and inotropes is indicated.</p> Signup and view all the answers

Explain how continuous Scvo2 monitoring provides a dynamic assessment of oxygen delivery during CPR and how it can be used to guide resuscitative measures in real-time.

<p>Because oxygen consumption remains relatively constant during CPR, as does arterial oxygen saturation (Sao2) and hemoglobin, changes in Scvo2 reflect changes in oxygen delivery by means of changes in cardiac output.</p> Signup and view all the answers

Describe the relationship between Scvo2, oxygen consumption, arterial oxygen saturation (Sao2), and hemoglobin levels during CPR and explain how changes in Scvo2 reflect changes in oxygen delivery to tissues.

<p>Oxygen consumption remains relatively constant during CPR, as does arterial oxygen saturation (Sao2) and hemoglobin, changes in Scvo2 reflect changes in oxygen delivery by means of changes in cardiac output.</p> Signup and view all the answers

What are the potential limitations and challenges associated with implementing transesophageal echocardiography (TEE) during CPR, and how does it compare to transthoracic echocardiography in this context?

<p>Transesophageal echocardiography (TEE) during CPR is an area of active research and has been associated with shorter chest compression pauses than transthoracic echocardiography.</p> Signup and view all the answers

Besides survival rates, what other long-term complications and challenges are associated with ECPR (Extracorporeal Cardiopulmonary Resuscitation) that need to be considered when implementing this rescue therapy?

<p>Common complications include coagulopathy, hemorrhage, limb ischemia, vascular injury, renal replacement therapy, and stroke.</p> Signup and view all the answers

Discuss the clinical significance of typical arterial and venous blood gas findings during CPR, and how these findings influence therapeutic decisions and interventions.

<p>Typical blood gas findings during CPR demonstrate venous respiratory acidosis and arterial respiratory alkalosis. Sao2 is usually greater than 94% during CPR and is of little value in titrating resuscitation therapy, except in the case of massive pulmonary embolism or unrecognized esophageal intubation.</p> Signup and view all the answers

Given the limitations of single-point-in-time laboratory measurements during CPR, how can continuous, oximetric Scvo2 monitoring provide a more comprehensive and informative assessment of CPR adequacy?

<p>Although Scvo2 indicates adequacy of CPR, a single measurement may not be as useful as continuous, oximetric Scvo2 monitoring.</p> Signup and view all the answers

Explain why successful resuscitation extends beyond achieving ROSC (Return of Spontaneous Circulation), and describe the key components of post-cardiac arrest care necessary for optimizing survival and neurological recovery.

<p>Management includes rapid diagnosis and treatment of the disorders that caused the arrest and complications of prolonged global ischemia. Simultaneous management of these two entities makes caring for a post–cardiac arrest patient particularly challenging. A comprehensive, goal- directed program of post–cardiac arrest care is necessary to optimize survival and neurologic recovery.</p> Signup and view all the answers

What is the primary mechanism by which hypothermic targeted temperature management (HTTM) improves survival and functional outcomes in comatose survivors of cardiac arrest?

<p>The text does not explain the mechanism.</p> Signup and view all the answers

How does arterial blood pressure monitoring (specifically invasive monitoring) contribute to guiding resuscitation, and what are the benefits and limitations of using arterial diastolic blood pressure as a surrogate for CPP?

<p>Invasive arterial blood pressure monitoring alone can be helpful in guiding resuscitation and should be used when an indwelling arterial pressure catheter is already in place. When adequate personnel are available, it is often feasible to cannulate the femoral artery during CPR, especially with ultrasound guidance.</p> Signup and view all the answers

Describe how use of ultrasound may aid clinical decision making during resuscitation from cardiac arrest. Provide specific examples.

<p>Ultrasound identifies corresponding cardiac activity in patients experiencing Pulseless Electrical Activity (PEA). Another example is the use of ultrasound guidance to cannulate the femoral artery during CPR.</p> Signup and view all the answers

When might intermittent arterial and venous blood sampling for gas or chemistry analysis be of value during CPR? Explain your answer.

<p>Other laboratory studies during CPR are typically not available in time to guide therapy but may serve to confirm a diagnosis following successful resuscitation. Serum electrolyte levels may be ordered to rule out hyperkalemia, hypokalemia, hypomagnesemia, hypercalcemia, and hypocalcemia</p> Signup and view all the answers

Define End-Tidal Carbon Dioxide (ETCO2). How does ETCO2 relate to coronary perfusion pressure during CPR?

<p>The partial pressure of CO2 in exhaled air at the end of expiration (PETco2). PETco2 depends on CO2 production, alveolar ventilation, and pulmonary blood flow (i.e., cardiac output) and correlates well with CPP and cerebral perfusion pressure during CPR.</p> Signup and view all the answers

During CPR, how does end-tidal carbon dioxide (PETco2) monitoring assist in the diagnosis and treatment of pulseless electrical activity (PEA)?

<p>PETco2 levels may be elevated in PEA with mechanical heart activity, indicating pulsatile flow not detectable by pulse palpation. This suggests a need for volume expansion, vasopressors, or inotropes.</p> Signup and view all the answers

Explain how coronary perfusion pressure (CPP) is calculated during CPR and why it's a critical parameter to monitor, even though direct measurement is often impractical in emergency department resuscitations.

<p>CPP is calculated by subtracting right atrial diastolic pressure from aortic diastolic pressure. It's critical because a minimum CPP of 15 mm Hg is necessary to achieve ROSC if initial defibrillation attempts have failed.</p> Signup and view all the answers

Describe the clinical utility of monitoring central venous oxygen saturation (Scvo2) during CPR and how failure to achieve a specific Scvo2 threshold correlates with the likelihood of achieving return of spontaneous circulation (ROSC).

<p>Scvo2 reflects oxygen delivery adequacy during CPR. Failure to achieve an Scvo2 of 40% or greater during CPR has a very high negative predictive value for ROSC, indicating that resuscitation efforts may need to be adjusted.</p> Signup and view all the answers

In the context of refractory ventricular fibrillation (VF) or pulseless ventricular tachycardia (pVT), contrast the recommendations for using amiodarone and lidocaine as first-line antiarrhythmic agents, referencing the clinical trial mentioned in the text regarding return of spontaneous circulation (ROSC).

<p>Both amiodarone and lidocaine are recommended as first-line agents. However, a recent trial showed only lidocaine resulted in an increased rate of ROSC, although neither therapy significantly improved survival.</p> Signup and view all the answers

Explain why intermittent arterial and venous blood sampling for gas or chemistry analysis is of limited utility during CPR, and under what specific circumstances might Sao2 be valuable in titrating resuscitation therapy?

<p>Blood gas analysis is often of limited use during CPR because the results are not available in time to guide therapy. Sao2 is typically high and uninformative, except in suspected cases of massive pulmonary embolism or unrecognized esophageal intubation.</p> Signup and view all the answers

What specific patient positioning is required for accurate IVC diameter measurement during an IVC collapse assessment?

<p>Supine position</p> Signup and view all the answers

Explain why the passive leg raise (PLR) maneuver is considered a dynamic assessment of volume responsiveness.

<p>PLR simulates a fluid bolus, shifting blood to the central circulation, allowing for observation of immediate cardiovascular response.</p> Signup and view all the answers

How is pulse pressure variation (PPV) calculated, and what physiological principle does it reflect?

<p>PPV is calculated as [(PPmax - PPmin) / PPmean] x 100, reflecting the impact of respiration on arterial pressure and, indirectly, cardiac preload.</p> Signup and view all the answers

In the context of IVC assessment, what distinguishes the criteria for volume responsiveness in spontaneously breathing patients versus mechanically ventilated patients?

<p>Spontaneously breathing patients: &gt;50% collapse suggests volume responsiveness; Mechanically ventilated patients: &gt;18% distensibility suggests volume responsiveness</p> Signup and view all the answers

Describe how the clinical interpretation of volume responsiveness, determined through dynamic measures, impacts the decision-making process for fluid therapy in post-arrest patients.

<p>It guides fluid administration by indicating if cardiac output will increase with fluids, helping to optimize tissue perfusion while avoiding over-resuscitation.</p> Signup and view all the answers

What specific ultrasound probe frequency is recommended for visualizing the IVC during an IVC collapse assessment?

<p>A low-frequency ultrasound transducer.</p> Signup and view all the answers

Detail the step-by-step procedure for performing the passive leg raise (PLR) technique to assess volume responsiveness.

<ol> <li>Place patient in semi-recumbent position (45 degrees); 2. Measure baseline blood pressure and heart rate; 3. Passively raise legs to 45-degree angle; 4. Maintain elevation for 1-2 minutes, monitoring BP and HR changes.</li> </ol> Signup and view all the answers

Identify the specific patient conditions that must be present to accurately interpret pulse pressure variation (PPV) as an indicator of volume responsiveness.

<p>Mechanically ventilated patients with normal heart rhythm and tidal volumes of 6-8 mL/kg.</p> Signup and view all the answers

Describe how factors such as patient positioning, intrathoracic pressure, and underlying medical conditions can confound the interpretation of IVC diameter and collapse.

<p>Patient positioning &amp; intrathoracic pressure may affect IVC diameter and collapse. Medical conditions can influence IVC compliance &amp; response to volume changes.</p> Signup and view all the answers

Explain the potential adverse outcomes associated with over-resuscitation during fluid therapy, particularly in the context of post-arrest care.

<p>Pulmonary edema and ARDS.</p> Signup and view all the answers

What actions should be taken if the increase in systolic blood pressure is equal to 9 mmHg after performing the passive leg raise (PLR) technique?

<p>Consider other factors and assessments to determine volume responsiveness.</p> Signup and view all the answers

Explain how positive pressure ventilation influences IVC diameter and collapsibility, and how these effects are accounted for when interpreting IVC assessments in mechanically ventilated patients.

<p>Positive pressure increases intrathoracic pressure, reducing IVC collapsibility. The distensibility index (&gt;18%) is used in ventilated patients to account for these pressure effects.</p> Signup and view all the answers

In patients with significant tricuspid regurgitation or pulmonary hypertension, how might the interpretation of IVC collapsibility as an indicator of volume responsiveness be affected?

<p>Tricuspid regurgitation and pulmonary hypertension increases right atrial pressure, leading to IVC distention and reduced collapsibility, even in hypovolemic patients.</p> Signup and view all the answers

Describe the physiological rationale behind using changes in pulse pressure during mechanical ventilation to predict fluid responsiveness.

<p>Respiration-induced changes in intrathoracic pressure affect venous return, ventricular preload, and stroke volume, resulting in pulse pressure variation predictive of fluid responsiveness.</p> Signup and view all the answers

How does the presence of spontaneous respiratory efforts in a mechanically ventilated patient affect the reliability and interpretation of pulse pressure variation (PPV) as a marker of volume responsiveness?

<p>Spontaneous respiratory efforts compromises PPV reliability as the ventilator no longer delivers consistent tidal volumes and pressures.</p> Signup and view all the answers

What are the limitations of relying solely on the passive leg raise (PLR) technique in patients with intra-abdominal hypertension or those in a Trendelenburg position?

<p>Intra-abdominal hypertension can restrict blood return from the legs, while Trendelenburg position already maximizes venous return, reducing the sensitivity of PLR.</p> Signup and view all the answers

Outline a strategy for integrating IVC assessment, passive leg raise (PLR), and pulse pressure variation (PPV) to create a comprehensive and nuanced evaluation of volume responsiveness in a complex post-arrest patient.

<p>Assess IVC; if inconclusive, perform PLR; in mechanically ventilated patients, use PPV. Integrate all with clinical assessment to guide fluid therapy.</p> Signup and view all the answers

In the context of post-arrest care, how does understanding volume responsiveness contribute to preventing secondary organ damage and improving overall patient outcomes?

<p>Optimizes cardiac output and tissue perfusion, reducing the risk of ischemia, acute kidney injury, and other complications.</p> Signup and view all the answers

How might significant changes in intrathoracic pressure, caused by conditions such as tension pneumothorax or severe asthma exacerbation, affect the accuracy of IVC diameter measurements and subsequent interpretation of volume responsiveness?

<p>Changes in intrathoracic pressure affects venous return, making IVC results less reliable for assessing volume responsiveness.</p> Signup and view all the answers

Discuss the ethical considerations involved in using dynamic measures of volume responsiveness in post-arrest patients who are unable to provide informed consent.

<p>Must balance the need for accurate assessment with the principles of beneficence, non-maleficence, and respect for patient autonomy.</p> Signup and view all the answers

How can the accuracy of IVC diameter measurements be optimized using ultrasound to minimize errors introduced by improper probe placement or patient movement?

<p>Proper probe placement and minimal patient movement ensures greater accuracy of the IVC diameter measurements.</p> Signup and view all the answers

Explain how the timing of dynamic assessments (IVC collapsibility, PLR, PPV) relative to interventions such as vasopressor administration or changes in ventilator settings can influence their interpretation.

<p>Vasopressors can affect cardiac output, and ventilator settings can alter intrathoracic pressure, influencing the IVC measurements.</p> Signup and view all the answers

In patients with pre-existing heart failure or significant valvular disease, how might the interpretation of dynamic measures of volume responsiveness (IVC, PLR, PPV) differ compared to patients with normal cardiac function?

<p>Valvular disease impacts cardiac filling and contractility which may affect the accuracy and interpretation of the measurements.</p> Signup and view all the answers

How can point-of-care ultrasound (POCUS) be utilized to enhance the assessment of volume status and guide fluid management decisions in post-arrest patients, beyond simply measuring IVC diameter?

<p>It can evaluate cardiac function, assess for pulmonary edema, and identify other factors influencing hemodynamic stability.</p> Signup and view all the answers

Describe the steps that should be taken to ensure the reliability and reproducibility of pulse pressure variation (PPV) measurements, particularly in situations where multiple providers are involved in patient care.

<p>Ensure proper arterial line placement, consistent ventilator settings, and standardized measurement techniques to minimize variability.</p> Signup and view all the answers

Discuss the potential challenges and limitations associated with using dynamic measures of volume responsiveness in morbidly obese patients.

<p>Obesity can affect IVC diameter measurement, PLR, and PPV.</p> Signup and view all the answers

Explain how the use of vasopressors or inotropes might affect the interpretation of the passive leg raise (PLR) technique in assessing volume responsiveness.

<p>Vasopressors can alter vascular tone and cardiac contractility, affecting the response to PLR; Inotropes improve cardiac function, which may affect the accuracy of the procedure.</p> Signup and view all the answers

How can the principles of shared decision-making be applied when discussing fluid management strategies and the use of dynamic measures of volume responsiveness with family members of post-arrest patients?

<p>Provide clear explanations of the benefits, risks, and limitations of fluid therapy. Acknowledge concerns to make appropriate decisions.</p> Signup and view all the answers

In patients with chronic obstructive pulmonary disease (COPD) or other conditions characterized by increased intrathoracic pressure, how might the interpretation of IVC collapsibility or distensibility be affected?

<p>COPD results in chronically elevated intrathoracic pressure, which may diminish IVC collapsibility, regardless of the patient's volume status.</p> Signup and view all the answers

What specific adjustments to the passive leg raise (PLR) technique might be necessary when assessing volume responsiveness in patients with lower extremity fractures or other musculoskeletal injuries?

<p>Modifications to reduce pain and prevent further injury.</p> Signup and view all the answers

Describe how the choice of mechanical ventilation mode (e.g., pressure control vs. volume control) and settings (e.g., tidal volume, PEEP) can influence the accuracy and reliability of pulse pressure variation (PPV) as an indicator of volume responsiveness.

<p>Volume control can allow for a standardized tidal volume. Higher PEEP can decrease venous return affecting the reliability of PPV as an indicator of volume responsiveness.</p> Signup and view all the answers

In patients with elevated intra-abdominal pressure (IAP), how is the interpretation of IVC collapsibility affected, and what alternative assessment methods might be more reliable?

<p>Elevated IAP increases pressure on the IVC, reducing its collapsibility. Alternative assessments include cardiac output monitoring or stroke volume variation.</p> Signup and view all the answers

Explain how the presence of significant arrhythmias, such as atrial fibrillation, can confound the interpretation of pulse pressure variation (PPV) as a marker of volume responsiveness.

<p>Arrhythmias cause irregular pulse pressure, making the measurement of PPV unreliable.</p> Signup and view all the answers

In the context of limited resources or equipment, what are the most practical and readily available methods for assessing volume responsiveness in post-arrest patients?

<p>Clinical assessment and passive leg raise may be the most readily available method.</p> Signup and view all the answers

How does the concept of 'fluid stewardship' relate to the use of dynamic measures of volume responsiveness in post-arrest care, and what strategies can be implemented to promote responsible fluid administration practices?

<p>It emphasizes that fluid administration should be based on accurate assessment to avoid both hypovolemia and hypervolemia.</p> Signup and view all the answers

In a patient with severe sepsis and septic shock, how might the interpretation of IVC collapsibility or distensibility as a marker of volume responsiveness be complicated by factors such as increased venous capacitance and endothelial dysfunction?

<p>Sepsis results in increased venous capacitance, reducing IVC collapsibility regardless of actual volume status.</p> Signup and view all the answers

What are the key steps involved in developing a standardized protocol for assessing volume responsiveness in post-arrest patients within a specific hospital or healthcare setting?

<p>Establish a multidisciplinary team. Select appropriate assessment measures. Provide training, and implement the protocol.</p> Signup and view all the answers

Describe how the principles of 'goal-directed therapy' (GDT) can be integrated with dynamic measures of volume responsiveness to optimize fluid management and improve outcomes in post-arrest patients.

<p>GDT involves using dynamic measures to guide fluid administration to achieve specific hemodynamic targets.</p> Signup and view all the answers

In patients with acute respiratory distress syndrome (ARDS), how might the interpretation of dynamic measures of volume responsiveness (e.g., PPV, IVC collapsibility) be affected by ventilator settings and strategies such as prone positioning?

<p>Prone positioning affects venous return potentially altering measures of volume responsiveness.</p> Signup and view all the answers

In the context of IVC assessment for volume responsiveness, how might significant intra-abdominal hypertension confound the interpretation of IVC diameter and collapsibility measurements?

<p>Elevated intra-abdominal pressure can compress the IVC, reducing its diameter and potentially leading to a false positive result for volume responsiveness, even if the patient is not actually volume-responsive.</p> Signup and view all the answers

Explain how the presence of tricuspid regurgitation could influence the accuracy of IVC collapsibility as a predictor of volume responsiveness.

<p>Tricuspid regurgitation can lead to elevated right atrial pressures, which are transmitted to the IVC, potentially causing it to appear more distended and less collapsible, even in a volume-responsive patient. This could lead to a false negative result.</p> Signup and view all the answers

How does the passive leg raise (PLR) technique simulate a fluid bolus, and what are the key physiological mechanisms underlying its effectiveness in predicting volume responsiveness?

<p>PLR simulates a fluid bolus by shifting venous blood from the lower extremities into the central circulation, increasing preload. This increase in preload will increase cardiac output, if the patient is volume responsive, and will result in an increase in systolic blood pressure &gt;10 mmHg.</p> Signup and view all the answers

Describe a clinical scenario where pulse pressure variation (PPV) might be unreliable in assessing fluid responsiveness, and explain the physiological reasons for its unreliability in this context.

<p>PPV may be unreliable in patients with spontaneous breathing or cardiac arrhythmias. Spontaneous breathing can cause irregular changes in intrathoracic pressure, affecting pulse pressure independent of volume status. Arrhythmias lead to inconsistent stroke volumes, making it difficult to interpret PPV as an indicator of volume responsiveness.</p> Signup and view all the answers

A patient presents with septic shock and is mechanically ventilated. Their initial IVC distensibility index is 15%. After a fluid bolus, it decreases to 10%, but their blood pressure remains unchanged. How would you interpret these findings in the context of volume responsiveness, and what additional steps might you take to guide further fluid management?

<p>The initial IVC distensibility index of 15% suggests that the patient may not be volume responsive. The decrease to 10% after a fluid bolus, along with the unchanged blood pressure, suggests the patient is not volume responsive and that further fluid administration may not be beneficial. Additional assessments such as echocardiography to assess cardiac function or other dynamic measures (e.g., pulse pressure variation) could provide further insights.</p> Signup and view all the answers

Flashcards

Epinephrine use in Arrest?

First-line vasopressor for cardiac arrest; dose is 1 mg IV/IO every 3-5 minutes, or Vasopressin 40 units IV push (alternative).

Antiarrhythmics for refractory VF/pVT?

Amiodarone (300mg IV/IO first dose, 150mg second) or Lidocaine (1-1.5 mg/kg first dose, 0.5-0.75 mg/kg second).

Treatment for torsades de pointes?

Magnesium sulfate 2-4g IV push.

Calcium dose for hyperkalemia?

1g calcium chloride IV or 3g calcium gluconate IV

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Ineffective CPR indicated by PETCO2?

Less than 10 mm Hg prompts CPR quality improvement.

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ScvO2 predicting no ROSC during CPR?

Less than 40% (100% negative predictive value).

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CPP target during CPR?

Minimum 15-20 mmHg (aortic diastolic - right atrial pressure).

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Two mechanical causes of PEA to assess?

Pericardial tamponade or Pulmonary embolism.

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ECPR time window for OHCA?

Initiate flow within 60 minutes of arrest onset.

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Three HTTM target temperature parameters?

32-36°C maintained for 24 hours then rewarm at 0.5°C/hour.

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First-line benzodiazepine doses for post-arrest seizures?

Lorazepam 0.1 mg/kg IV (max 4mg) or Midazolam 0.2 mg/kg IM (max 10mg).

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Immediate PCI post-ROSC indicated when?

STEMI on ECG or High suspicion of ACS without non-cardiac cause.

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Oxygenation target post-ROSC?

Titrate FiO2 to SpO2 ≥94% (avoid PaO2 >300 mmHg).

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Two lactate trends indicating improving perfusion?

Decreasing serial levels or Rising ScvO2 >65%.

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Mnemonic for epinephrine dosing during CPR?

"1-3-5 Rule": 1 mg every 3-5 minutes during CPR.

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Vasopressin ADVANTAGE over epinephrine?

None no survival benefit (consider if epinephrine fails).

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ETCO2 spike indicates what event?

ROSC - sudden ↑ from <10 mmHg to >40 mmHg.

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Three CPR quality improvements if ETCO2 <10?

Adjust compression rate, Adjust depth, Ensure recoil.

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Ultrasound finding in pseudo-PEA?

Cardiac activity on echo without palpable pulses.

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ECPR complication requiring monitoring?

Limb ischemia (femoral cannulation).

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Post-ROSC anticoagulation for ACS?

Dual antiplatelets: aspirin + ticagrelor (preferred over clopidogrel).

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Absolute contraindication for fibrinolytics post-ROSC?

CPR-related trauma (e.g., pneumothorax/pulmonary hemorrhage).

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Three methods to induce HTTM in ED?

Ice packs, Cooling blankets, 4°C saline infusion (1-2L).

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How long maintain HTTM after target reached?

24 hours minimum before rewarming.

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Mnemonic for calcium doses?

"1-3 Rule": 1g chloride or 3g gluconate.

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Sodium bicarbonate dose in TCA overdose?

1-2 mEq/kg IV.

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Dextrose dose for hypoglycemia in arrest?

25-50g IV (D50W standard).

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Post-ROSC Scv02 goal?

65% (adequate oxygen delivery).

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Three dynamic measures of volume responsiveness?

IVC collapse <50%, Passive leg raise, Pulse pressure variation.

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First intervention for venous hyperoxia (Scv02 >80%)?

Reduce vasopressors and Optimize volume status.

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ECG finding requiring transcutaneous pacing?

3rd-degree block or New bifascicular block post-ROSC.

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Preferred beta blocker in labile post-arrest patients?

Esmolol drip (short-acting, titratable).

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Timeframe for lactate clearance monitoring?

Q2-4h initially (decrease >10%/hour).

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Three contraindications to HTTM?

Active bleeding, DNR status, Terminal illness (relative).

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PCI timing with HTTM?

Proceed immediately – don't delay cooling.

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Post-ROSC anticoagulation caution?

Monitor for CPR-related injuries (rib fractures, liver/spleen trauma).

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Mnemonic for post-arrest care priorities?

ACS evaluation, BP management, Cooling/TTM, Seizure prevention.

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Three CPR parameters to monitor?

Rate (100-120/min), Depth (2-2.4"), Recoil (complete).

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ETCO2 use in tension pneumothorax?

Rise after needle decompression confirms success.

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Vasopressor choice in pseudo-PEA?

Norepinephrine infusion (0.1-0.5 mcg/kg/min).

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Post-ROSC hypertension management?

Permissive hypertension initially (MAP 65-90mmHg).

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Three predictors of poor neurologic outcome?

No pupillary/corneal reflexes at 72h, Myoclonus status, NSE >60ng/mL.

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ECPR candidate criteria?

Witnessed arrest, Bystander CPR, Initial shockable rhythm.

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Epinephrine timing in cardiac arrest?

Administer ASAP in non-shockable rhythms, after failed defibrillation attempts in shockable ones.

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Hemodynamic-directed resuscitation?

Adjust compressions and vasopressors to systolic BP of 90 mm Hg, arterial relaxation pressure of 20-25 mm Hg.

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Coronary Perfusion Pressure (CPP)?

Difference between aortic and right atrial pressures during diastole.

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Electrocardiographic (ECG) monitoring during CPR?

Monitors electrical activity but not mechanical function. May show activity without effective pumping.

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PETco2 determinants?

Depends on CO2 production, alveolar ventilation, and pulmonary blood flow (cardiac output).

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PETco2 measurement?

Waveform capnography after intubation.

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PETco2 monitoring use during CPR?

Helps assess CPR inadequacy and guide improvements in compression rate, depth, or recoil.

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Echocardiography use during PEA?

Distinguishes EMD from pseudo-EMD; diagnoses tamponade/PE; guides pericardiocentesis.

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Blood gas role during CPR?

Arterial and venous blood sampling for gas or chemistry analysis has limited value. Sao2 typically above 94% during CPR.

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CPP calculation?

Calculated by subtracting right atrial diastolic pressure from aortic diastolic pressure.

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IVC Collapse Assessment

Change in Inferior Vena Cava diameter with respiration, assessed via ultrasound to evaluate volume responsiveness.

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IVC Diameter Measurement

Evaluates IVC diameter during inspiration and expiration.

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IVC Collapse Threshold

In spontaneously breathing patients, >50% diameter decrease suggests responsiveness.

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IVC Distensibility Index

In mechanically ventilated patients, >18% distensibility suggests responsiveness.

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Passive Leg Raise (PLR)

Simulates a fluid bolus by shifting blood from legs to central circulation.

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PLR Technique

Lay flat and lift legs to 45 degrees for 1-2 minutes to observe BP/HR changes.

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PLR Response Indicator

A systolic blood pressure increase >10 mmHg indicates volume responsiveness.

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Pulse Pressure Variation (PPV)

Difference between max and min pulse pressure during respiratory cycle.

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PPV Calculation

[(PPmax - PPmin) / PPmean] x 100.

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PPV Threshold for Responsiveness

PPV >13% typically indicates volume responsiveness.

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Volume Responsiveness

Cardiac output will likely increase with fluid administration

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Fluid Therapy Guidance

Using dynamic measures alongside overall patient assessment.

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Over-Resuscitation Risks

Avoid fluid overload, which can lead to lung issues.

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Volume Responsiveness Goal

Optimizing heart function and blood flow to organs.

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Factors Affecting IVC

Patient's position, chest pressure, and existing health issues.

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PPV Requirements

Requires arterial line, mechanically ventilated, normal rhythm, 6-8 mL/kg tidal volume.

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Study Notes

  • IV/IO access should be obtained for ongoing resuscitation that fails to abort following CPR and defibrillation.

Pharmacology

  • Epinephrine 1 mg every 3 to 5 minutes is recommended, based on improved survival and ROSC.
  • Vasopressin (40 IV push) offers no advantage as a substitute for epinephrine but can be considered.
  • High-dose epinephrine is not recommended for routine use.
  • Epinephrine should be administered as soon as feasible for non-shockable rhythms, and after initial defibrillation attempts have failed for shockable rhythms.
  • Hemodynamic directed resuscitation involves titrating chest compressions and vasopressor therapy to hemodynamic variables.
  • Titration of chest compressions and vasopressor therapy to maintain systolic blood pressure of 90 mm Hg and a CPP of 20 mm Hg during CPR demonstrated improved outcomes in animal models.
  • CPP during CPR is defined as the difference between aortic and right atrial pressures during relaxation (CPR diastole).
  • Titrate vasopressors to an arterial relaxation pressure of at least 20 to 25 mm Hg.
  • For VF or pVT refractory to defibrillation, amiodarone (first dose: 300 mg IV/IO; second dose: 150 mg IV/IO) or lidocaine (first dose: 1 to 1.5 mg/kg IV/IO; second dose: 0.5 to 0.75 mg/kg IV/IO) are recommended as first-line agents.
  • Lidocaine increased the rate of ROSC, however, neither therapy resulted in statistically significant improvements in survival.
  • Other medications that may be of value in special cases include magnesium sulfate in torsades de pointes (2 to 4g IV), calcium in hyperkalemia (1 g calcium chloride IV or 3 g calcium gluconate IV), sodium bicarbonate in TCA overdose (1 to 2 mEq/kg), and dextrose in hypoglycemia (25 to 50g IV).
  • Routine administration of atropine outside the setting of bradycardia is not beneficial.

Devices and Techniques - Monitoring

  • If the inadequacy of CPR is recognized early, consider more invasive measures such as ECPR or coronary angiography and PCI with ongoing chest compressions if these modalities are readily available and there is significant potential for survival with good neurologic function.
  • Clear indications that CPR is inadequate (based on appropriate monitoring techniques) can be a contributing factor in the decision to cease resuscitation efforts
  • Electrocardiographic monitoring during cardiac arrest indicates the presence or absence of electrical but not mechanical activity.
  • Myocardial blood flow depends on CPP.
  • No single monitoring technique provides all desired information during a resuscitation.

End- Tidal Carbon Dioxide

  • The partial pressure of CO2 in exhaled air at the end of expiration (PETco2) can be a reliable indicator of cardiac output during CPR.
  • PETco2 is most reliably measured through waveform capnography after endotracheal intubation, though can also be used with a supraglottic airway device or bag mask.
  • PETco2 depends on CO2 production, alveolar ventilation, and pulmonary blood flow (i.e., cardiac output) and correlates well with CPP and cerebral perfusion pressure during CPR.
  • ROSC causes immediate and significant increases in PETco2.
  • PETco2 monitoring can detect ROSC at any time during the chest compression cycle, providing valuable guidance for pharmacologic therapies and minimizing the need for a pulse check when organized rhythms are detected.
  • Resuscitation after cardiac arrest is likely to fail if PETco2 values of 10 mm Hg or more are not achieved.
  • Values less than 10 mm Hg should prompt the clinician to enhance the quality of CPR by improving compression rate, depth, or recoil.
  • PETco2 monitoring also can aid in the diagnosis and treatment of PEA.
  • Patients in a state of PEA with mechanical heart activity may have pulsatile flow that simply cannot be detected by palpation of a pulse.
  • In such cases, PETco2 levels may be elevated, even without compressions.
  • Use of ultrasound in such cases can identify corresponding cardiac activity.
  • In these cases, volume expansion or the use of vasopressors and inotropes is indicated.
  • PETco2 monitoring is also useful in rapidly detecting the success of tension pneumothorax decompression, pericardiocentesis for pericardial tamponade, and fluid resuscitation for hypovolemia.
  • PETco2 monitoring is valuable in patients after ROSC to monitor endotracheal tube placement (waveform capnography recommended), titrate minute ventilation to avoid hyperventilation, and detect sudden hemodynamic deterioration.

Central Venous Oxygen Saturation

  • Central venous oxygen saturation, Scvo2, provides an additional method to monitor the adequacy of resuscitative measures.
  • The mixed venous blood oxygen saturation in the pulmonary artery (SvO2) represents the oxygen remaining in the blood after systemic extraction.
  • Studies have shown a close correlation between Scvo2 and SvO2 during CPR.
  • Because oxygen consumption remains relatively constant during CPR, as does arterial oxygen saturation (Sao2) and hemoglobin, changes in Scvo2 reflect changes in oxygen delivery by means of changes in cardiac output.
  • Failure to achieve an Scvo2 of 40% or greater during CPR has had a negative predictive value for ROSC of almost 100%.
  • Scvo2 also helps to detect ROSC rapidly without interruption of chest compressions, because ROSC results in a rapid increase in Scvo2 as oxygen delivery to tissues dramatically increases.
  • Scvo2 monitoring is also useful in the post–cardiac arrest period for hemodynamic optimization and for recognition of any sudden deterioration in the patient’s clinical condition

Echocardiography

  • The main use of echocardiography is diagnostic, especially in patients with PEA by distinguishing EMD from pseudo- EMD.
  • It may also help diagnose mechanical causes of PEA such as pericardial tamponade and pulmonary embolism, and in guiding pericardiocentesis.
  • Transesophageal echocardiography (TEE) during CPR has been associated with shorter chest compression pauses than transthoracic echocardiography.
  • TEE may provide an additional visual method to monitor effectiveness of chest compressions in real time by directly visualizing changes in the left ventricle with changes in chest compression technique.
  • In the post- arrest period, echocardiography can prove valuable in evaluating myocardial dysfunction and determining the need for mechanical assistance of the failing heart.

Extracorporeal Cardiopulmonary Resuscitation

  • Use of VA- ECMO as rescue therapy for refractory adult and pediatric IHCA, deemed ECPR, is a well- established practice in many specialized centers.
  • Timely arterial and venous access, placement of cannulas, and initiation of ECPR support is critical to success.
  • ECPR is most successful when flow is initiated within 60 minutes of cardiac arrest onset.
  • Survivors typically require 2 to 5 days before they can be successfully weaned from ECMO support.
  • Common complications include coagulopathy, hemorrhage, limb ischemia, vascular injury, renal replacement therapy, and stroke.

Laboratory Testing

  • Intermittent arterial and venous blood sampling for gas or chemistry analysis is of limited use during CPR.
  • Typical blood gas findings during CPR demonstrate venous respiratory acidosis and arterial respiratory alkalosis.
  • Sao2 is usually greater than 94% during CPR and is of little value in titrating resuscitation therapy, except in the case of massive pulmonary embolism or unrecognized esophageal intubation.
  • Although Scvo2 indicates adequacy of CPR, a single measurement may not be as useful as continuous, oximetric Scvo2 monitoring.
  • Other laboratory studies during CPR are typically not available in time to guide therapy but may serve to confirm a diagnosis following successful resuscitation.
  • Serum electrolyte levels may be ordered to rule out hyperkalemia, hypokalemia, hypomagnesemia, hypercalcemia, and hypocalcemia
  • Low hemoglobin levels may indicate bleeding, but the initial hemoglobin value may be normal in acute exsanguinating hemorrhage, owing to a lack of rapid vascular and interstitial compartment equilibration.

Arterial Blood Pressure and Coronary Perfusion Pressure

  • Successful resuscitation of the arrested heart depends on generating adequate CPP during CPR.
  • CPP during CPR is calculated by subtracting right atrial diastolic pressure from aortic diastolic pressure.
  • A minimum CPP of 15 mm Hg is necessary to achieve ROSC if initial defibrillation attempts have failed.
  • CPP monitoring is rarely feasible in ED resuscitations of cardiac arrest patients, as it requires an indwelling arterial pressure catheter and central venous catheter, both transduced properly to provide simultaneous readings.
  • Invasive arterial blood pressure monitoring alone can be helpful in guiding resuscitation and should be used when an indwelling arterial pressure catheter is already in place.
  • It is often feasible to cannulate the femoral artery during CPR, especially with ultrasound guidance.
  • Human studies have shown that radial or femoral arterial relaxation pressures reliably reflect aortic relaxation pressures during CPR.
  • Monitoring arterial diastolic blood pressure as a surrogate for CPP has been proposed.
  • Titrating resuscitation efforts to arterial relaxation (diastolic) pressure is less reliable than CPP since improper CPR (e.g., leaning on chest during CPR diastole and hyperventilation) can cause undetected elevations in the right atrial pressure, reducing coronary perfusion.
  • It is reasonable to titrate resuscitation efforts to achieve an arterial relaxation (diastolic) pressure of 20 to 25 mm Hg or more when invasive arterial pressure monitoring is available.
  • Invasive arterial pressure monitoring during CPR may also help detect ROSC and assist in serial arterial blood gas monitoring.
  • Arterial and central venous catheters are usually placed in the post–cardiac arrest phase of care, 10% to 20% of patients initially achieving ROSC will re- arrest, making these modalities helpful during the patient’s subsequent resuscitation.

Outcomes - Post Cardiac Arrest Care

  • Resuscitation of a cardiac arrest victim does not end with ROSC.
  • Management includes rapid diagnosis and treatment of the disorders that caused the arrest and complications of prolonged global ischemia.
  • Simultaneous management of these two entities makes caring for a post–cardiac arrest patient particularly challenging.
  • A comprehensive, goal- directed program of post–cardiac arrest care is necessary to optimize survival and neurologic recovery.

Hypothermic Targeted Temperature Management (HTTM)

  • HTTM in comatose survivors of cardiac arrest has been shown to improve survival and functional outcome.
  • These studies enrolled only comatose survivors of OHCA that were witnessed arrests and had an initial rhythm of VF.

Volume Responsiveness

  • Dynamic measures to assess volume responsiveness in post-arrest patients include IVC collapse, passive leg raise, and pulse pressure variation.

IVC Collapse Assessment

  • Assesses Inferior Vena Cava diameter change with respiration via ultrasound.
  • Position the patient in a supine position
  • Use a low-frequency ultrasound transducer to visualize the IVC in the longitudinal axis, just proximal to the hepatic veins.
  • Measure the IVC diameter during both inspiration and expiration.
  • A collapse of >50% suggests volume responsiveness in spontaneously breathing patients.
  • A distensibility index of >18% suggests volume responsiveness in mechanically ventilated patients

Passive Leg Raise Technique

  • The maneuver simulates a fluid bolus by shifting blood from the lower extremities to the central circulation.
  • Position the patient in a semi-recumbent position (45 degrees).
  • Measure baseline blood pressure and heart rate.
  • Then, passively raise the patient's legs to a 45-degree angle.
  • Maintain leg elevation for 1-2 minutes and monitor changes in blood pressure and heart rate.
  • An increase in systolic blood pressure >10 mmHg indicates volume responsiveness.

Pulse Pressure Variation Method

  • Requires an arterial line to measure continuous blood pressure.
  • Pulse pressure variation (PPV) is the difference between the maximum and minimum pulse pressure during a respiratory cycle.
  • PPV is calculated as [(PPmax - PPmin) / PPmean] x 100.
  • A PPV >13% generally indicates volume responsiveness in mechanically ventilated patients with normal heart rhythm and tidal volumes of 6-8 mL/kg.

Interpreting IVC Results

  • In spontaneously breathing patients, >50% collapse suggests volume responsiveness.
  • In mechanically ventilated patients, >18% distensibility suggests volume responsiveness.
  • Factors like patient positioning, intrathoracic pressure, and underlying medical conditions can affect IVC diameter and collapse.

Clinical Implications Of Volume Responsiveness

  • Volume responsiveness indicates that the patient's cardiac output will increase with fluid administration.
  • Use dynamic measures in conjunction with clinical assessment to guide fluid therapy.
  • Over-resuscitation should be avoided as it can lead to adverse outcomes, including pulmonary edema and ARDS.
  • Volume responsiveness assessment helps optimize cardiac output and tissue perfusion.

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