Resuscitation Pharmacology

• IV or IO access is needed for resuscitation that fails after CPR and defibrillation.

Pharmacology

• Epinephrine 1 mg every 3–5 minutes is recommended for improved survival and ROSC.
• Vasopressin provides no advantage over epinephrine but can be considered at 40 IV push.
• High-dose epinephrine is not routinely recommended.
• Administer epinephrine ASAP for non-shockable rhythms and after failed defibrillation attempts in shockable rhythms.
• Hemodynamic-directed resuscitation involves titrating chest compressions and vasopressor therapy to hemodynamic variables.
• Animal models show improved outcomes by maintaining a systolic blood pressure of 90 mm Hg and a coronary perfusion pressure (CPP) of 20 mm Hg
• CPP = aortic and right atrial pressures during relaxation (CPR diastole).
• Aim for arterial relaxation pressure of at least 20–25 mm Hg when titrating vasopressors.
• For refractory VF/pVT, administer amiodarone (300 mg IV/IO, then 150 mg IV/IO) or lidocaine (1–1.5 mg/kg IV/IO, then 0.5–0.75 mg/kg IV/IO) as first-line agents.
• Lidocaine was shown to increase rate of ROSC in recent trial, but statistically insignificant improvements in survival were observed
• Other medications that can be used are:
  • Magnesium sulfate for torsades de pointes (2–4g IV)
  • Calcium for hyperkalemia (1 g calcium chloride IV or 3 g calcium gluconate IV)
  • Sodium bicarbonate for tricyclic antidepressant overdose (1–2 mEq/kg)
  • Dextrose for hypoglycemia (25–50g IV)
• Routine atropine administration outside of bradycardia is not beneficial.

Devices and Techniques

• Besides CPR performance parameters, physiological monitoring can optimize CPR quality.
• Invasive measures like ECPR or coronary angiography and PCI should be considered early where there is significant potential for survival with good neurologic function.
• After a prolonged arrest, signs that CPR is inadequate (based on monitoring) can contribute to stopping resuscitation.
• Traditional monitoring involves ECG and palpating carotid or femoral artery pulses, these do not provide reliable information on CPR effectiveness or prognosis.
• No single monitoring technique provides all desired information, and initiating modalities during CPR can be challenging.
• CPP, end-tidal carbon dioxide (ETco2), and central venous oxygen saturation (Scvo2) monitoring can detect inadequate CPR with high specificity.

End-Tidal Carbon Dioxide

• PETco2 is a reliable indicator of cardiac output during CPR
• Waveform capnography is the most reliable measurement through endotracheal intubation, but can also be used with a supraglottic airway device or bag mask
• PETco2 depends on CO2 production, alveolar ventilation, and pulmonary blood flow, and correlates 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.
• ROSC causes immediate and significant PETco2 increases.
• PETco2 monitoring can detect ROSC at any time during chest compression cycle.
• PETco2 values 10 mm Hg is the minimum threshold to target, if it is not achieved then CPR should be enhanced.
• PETco2 monitoring can aid in PEA diagnosis and treatment, PEA patients with mechanical heart activity may have pulsatile flow not detected by pulse palpation, with elevated PETco2 levels even without compressions.
• It can also rapidly detect successful tension pneumothorax decompression, pericardiocentesis for pericardial tamponade, and fluid resuscitation for hypovolemia.
• PETco2 monitoring is valuable post-ROSC for:
  • Monitoring endotracheal tube placement (waveform capnography recommended).
  • Titrating minute ventilation to avoid hyperventilation.
  • Detecting sudden hemodynamic deterioration.

Central Venous Oxygen Saturation

• Scvo2 monitors the adequacy of resuscitative measures.
• Scvo2 correlates with SvO2 during CPR.
• Changes in Scvo2 reflect changes in oxygen delivery via changes in cardiac output.
• Continuous Scvo2 monitors can be placed like regular central venous catheters, used to monitor Scvo2 in real time.
• Normal Scvo2 values range from 60% to 80%.
• During cardiac arrest and CPR, values range from 25% to 35%, indicating enhanced oxygen extraction.
• Failure to achieve an Scvo2 of 40%+ during CPR has a negative predictive value for ROSC nearing 100%.
• Scvo2 detects ROSC without stopping compressions, as ROSC results in a rapid increase in Scvo2.
• Scvo2 monitoring is useful post–cardiac arrest for hemodynamic optimization and recognizing sudden clinical deterioration.

Echocardiography

• Echocardiography is mainly diagnostic, distinguishing EMD from pseudo-EMD.
• It may diagnose mechanical causes of PEA like pericardial tamponade and pulmonary embolism.
• TEE during CPR is associated with shorter chest compression pauses than transthoracic echocardiography.
• TEE visually monitors chest compression effectiveness in real time.
• Post-arrest, echocardiography valuably evaluates myocardial dysfunction and determines need for mechanical assistance.

Extracorporeal Cardiopulmonary Resuscitation

• VA-ECMO as rescue therapy for refractory adult and pediatric IHCA (ECPR) is used in specialized centers, despite lack of RCT evidence.
• Observational and case-control studies suggest benefit in selected refractory OHCA patients, with survival rates ranging from 11%–33%.
• Timely arterial/venous access, cannulation, and ECPR initiation are critical.
• ECMO flow initiation should ideally occur within 60 minutes of cardiac arrest onset.
• Survivors typically require 2–5 days before weaning from ECMO support.
• Common complications include coagulopathy, hemorrhage, limb ischemia, vascular injury, renal replacement therapy, and stroke.
• Successful ECPR programs require training and coordination among EMS, EDs, specialties, and ICUs.
• Feasibility and value of implementation outside high-volume centers needs further research.

Laboratory Testing

• Intermittent arterial and venous blood sampling for gas/chemistry analysis has limited use during CPR.
• Typical CPR blood gas findings show venous respiratory acidosis and arterial respiratory alkalosis.
• Sao2 is usually greater than 94% during CPR and is less useful except for massive pulmonary embolism or unrecognized esophageal intubation.
• Continuous Scvo2 monitoring is preferred over single measurements.
• Other laboratory studies during CPR are typically not available in time to guide therapy but may serve to confirm a diagnosis after resuscitation.
• Serum electrolyte levels should be ordered to rule out:
  • Hyperkalemia
  • Hypokalemia
  • Hypomagnesemia
  • Hypercalcemia
  • Hypocalcemia
• Treat empirically with clinical suspicion.
• Low hemoglobin may indicate bleeding, initial hemoglobin may be normal in acute exsanguinating hemorrhage.

Arterial Blood Pressure and Coronary Perfusion Pressure

• Successful resuscitation depends on generating adequate CPP during CPR.
• CPP is calculated by subtracting right atrial diastolic pressure from aortic diastolic pressure.
• CPP of 15 mm Hg+ is needed for ROSC after failed defibrillation.
• CPP monitoring is rarely feasible in ED resuscitations.
• Invasive arterial blood pressure monitoring alone can help guide resuscitation.
• Femoral artery cannulation during CPR is often feasible with ultrasound guidance.
• 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.
• It is reasonable to titrate resuscitation efforts to achieve an arterial relaxation (diastolic) pressure of 20–25 mm Hg+ when invasive arterial pressure monitoring is available.
• Invasive arterial pressure monitoring may detect ROSC and assist in serial arterial blood gas monitoring.
• Arterial and central venous catheters are usually placed post–cardiac arrest, but 10-20% of patients initially achieving ROSC will re-arrest.

Post-Cardiac Arrest Care

• Resuscitation doesn't end with ROSC.
• Management includes treating the cause of the arrest and complications of prolonged global ischemia.
• A comprehensive, goal-directed program of post–cardiac arrest care optimizes survival and neurologic recovery.

Hypothermic Targeted Temperature Management (HTTM)

• HTTM in comatose survivors of cardiac arrest improves survival and functional outcome.
• Studies enrolled only comatose survivors of witnessed OHCA with initial VF.