SS Hemodynamic Monitoring - Spring 24.pdf

Hemodynamic Monitoring Clay Freeman, DNP, CRNA Essentials in Anesthesia 1 Objectives Readings: Barash: Chap. 26 Describe the use of non-invasive and invasive monitors Understand principles of science for each monitoring technique Identify basic and advanced monitoring modalities and their indications in the clinical setting Demonstrate equipment checking and maintenance Detail safe advanced monitoring insertion techniques ØSelf Study: Ultrasound maneuvers & anatomic planes 2 Hemodynamic Monitoring Goal of hemodynamic monitoring is to assure adequate perfusion for delivery of O2 to tissues Arterial blood pressure is used as a surrogate for determining perfusion Blood pressure measurement is consistently used & researched but… has poor correlation with O2 delivery to tissues 3 Standard of Practice Standard 9 - Monitoring, Alarms: Monitor, evaluate, and document the patient’s physiologic condition as appropriate for the procedure and anesthetic technique. When a physiological monitoring device is used, variable pitch and threshold alarms are turned on and audible. Document blood pressure, heart rate, and respiration at least every five minutes for all anesthetics c. Cardiovascular Monitor and evaluate circulation to maintain patient’s hemodynamic status. Continuously monitor heart rate and cardiovascular status. Use invasive monitoring as appropriate. 4 Noninvasive Blood Pressure Sphygmomanometry: Auscultation of Korotkoff sounds created via turbulent flow due to partial collapse of the constricted artery Allows for measurement of systolic and diastolic pressures 5 Noninvasive Blood Pressure Oscillometry: Automated NIBP measures pressure fluctuations due to pulsations transmitted to solid-state transducers. Microprocessors then interpret these pressure changes MAP measured at the greatest amplitude of oscillations SBP recorded upon first appearance of blood flow DBP is calculated or measured at last detectable oscillation (least reliable) 6 NIBP Limitations Deviation of ±10mmHg compared to intraarterial measurements Limitations: Proper cuff sizing Calibrated for brachial artery only Limbs with central access (PICC), Fractures, or AV fistula ~ lymph node dissection Obese patients Severe arterial stenosis Arrythmias MAP < 65mmHg Sudden hyper- or hypotension Delays in measurement timing (> 2min) Ø Surgeon positioning Complications: Pain Neuropathy Petechiae & Ecchymoses Venous stasis à Edema à Compartment syndrome Peripheral ischemia Distal IV interference 7 NIBP Limitations Proper cuff sizing: 2) Width: bladder should extend from 40-75% of the distance from your elbow to your shoulder Width 1) Length: The bladder should cover 80-100% of the distance around your upper arm. Length 8 Peñáz Technique Dynamic monitoring involving photoplethysmography and a closed-loop pressure cuff. Arterial pressure is kept consistent via a cuff placed on the patient’s finger while infrared beams are used to measure flow waveforms. Predictive processing keeps artery at a constant pressure Reported waveforms are analyzed and calculated to provide dynamic vital signs. HR, BP, CO, SV, SVV/PPV, SVR* Subject to similar limitations as NIBP 9 Invasive Monitoring Vascular Cannulation gives practitioners continuous hemodynamic values by capturing pressure waves transmitted to a transducer for further analysis Aside from guiding therapy, vascular cannulation can also serve to aid interventions to mitigate surgical risks, and provide further diagnostic clues 10 Transducer System fluid-filled tubing propagates the force of the pressure wave to transducer that converts the displacement of a silicon crystal into voltage changes. Fluid-filled motion systems are dependent on factors of mass, elasticity, and friction. Electrical signals are then amplified, filtered and displayed as a pressure tracing. Reliable waveforms require a balance of Frequency (pulse rate) and damping coefficient Ultimate output displayed is a Fourier Analysis of multiple combined Sine waves Translation: Transducing systems are subject to errors based on the physical properties of fluid motion and the quality of the catheter-transducer-amplification system 11 Wheatstone Bridge undergoing Hydraulic Coupling Process of hydraulic coupling: Bridge is bent via mechanical forces à resistance is changed à voltage differential created 12 Damping Coefficient The transducer is hydraulically connected to the vessel by a fluid-containing system so it is subject to frictional resistance Therefore, any change in pressure is not immediately transmitted to the transducer diaphragm. This delay in response is known as Damping Damping normally prevents a system from overresponding to a change 13 Overdamped Overdamping = too HIGH of resistance Overdamp Waveform appears with slurred upstroke, absent dicrotic notch, and loss of fine detail SBP is underestimated > Pinched DBP is overestimated However, MAP remains accurate Causes of overdamping include: Blood clots Air bubbles Kinks in the system Extensions (stopcocks/tubing) Malpositioned catheters 14 Underdamped Underdamping = too LOW of resistance Underdamp Waveform appears with exaggerated peaks and troughs in the waveform SBP is overestimated > Stretched DBP is underestimated However, MAP remains accurate Causes of underdamping include: Excessively rigid/short/narrow tubing Tachycardia 15 Square Test To assess frequency and damping characteristics of the transducing system, a “Fast Flush” test is performed Rapid introduction of a high-pressure pulse into the transducing system creates a waveform that reverberates at a frequency and diminishes over time in accordance with resistance Overdamped: minimal to no oscillations The practitioner then examines the characteristics of the resonant waves recorded Transducer systems work best when: Tubing is short & stiff Mass of the fluid is small Number of connections/stopcocks is limited Underdamped: excessive oscillations 16 Calibration Zeroing: The transducer should be zeroed by opening the transducer to atmosphere at its three-way stopcock This exposes the transducer to atmospheric pressure to establish the zero pressure reference value against which all intravascular pressures are measured. Leveling: Establishes the transducer in relation to the hydrostatic pressure exerted by the fluid column. The transducer should be even with the chamber or vessel in which the pressure is to be measured 17 Hydrostatic Pressure This hydrostatic pressure is proportional to the height of the fluid column. Proper leveling of the transducer negates the effects of hydrostatic pressure on the system being analyzed. Transducers are placed at the level of the right atrium for blood and heart chamber pressures. Exception: Level of Circle of Willis for cerebral perfusion pressures. Example 1 cm = 0.74 mmHg 1 in = 2 mmHg As blood flows vertically from the heart, there will be a reduction in arterial pressure that is related to the weight of a column of blood: consider a patient in a sitting position such that the external auditory canal (EAC) is 10 inches above the blood pressure cuff on the arm. If MAP of the arm cuff is 65 mmHg, the MAP at the EAC would be ≤ _____mmHg 18 Arterial Monitoring Current Gold Standard for blood pressure monitoring Indications: Frequent blood sampling (ABGs) Continuous real-time monitoring when rapid changes are anticipated, Major fluid shifts or probable blood loss Hx of CV disease processes (valvular disease, CAD, stroke, poor EF, etc.) Pharmacologic manipulation Mechanical manipulation (cardiovascular surgery) Failure of indirect BP monitoring (morbid obesity, burned extremity, etc) IABP counterpulsation or LVAD Deliberately induced hypo- or hyper-tensive technique Major Cardiac, Vascular, Trauma or Neuro surgery Long term administration of vasoactive drug infusions (Post-op) Supplementary diagnostic information desired 19 Complications Hematoma (Femoral: retroperitoneal) Thrombosis/embolization Limb ischemia Idiopathic blood loss Arteriovenous fistula Infection Nerve damage Vasospasm Skin necrosis local to catheter site Continuous flush device infuses ~3ml/hr: risk of hypervolemia in neonates increased risk with heparin 20 Allen’s test Perform Modified Allen’s Test: 1) 2) 3) 4) Occlude Radial & Ulnar artery, Bend patient’s elbow to lift hand for exsanguination, Release Ulnar artery to observe recirculation time, Repeat to compare to Radial artery recirculation Normal/positive Allen’s test = < 10 seconds Negative Allen’s test = puncture contraindicated Refill timing should be similar between the 2 tests Negative Allen’s test occurs in less than 1% of patients Dorsalis pedis – to assess collateral circulation of the posterior tibialis: compress the dorsalis pedis pulse, then elevate the foot until the plantar skin blanches. Finally, lower the leg to dependency and observe for recoloration. Normal recirculation indicates the posterior tibial artery flow is adequate. 21 Seldinger Technique 15-30° Argyle™ 15-30° Arrow™ 22 Arterial Waveform Left ventricular ejection initiates a pressure wave that is propagated through the aorta toward the periphery 1. Systolic upstroke represents the left ventricular ejection. 2. The peak systolic pressure is followed by a rapid decrease in pressure as ventricular contraction ends Resultant peripheral pressure waveform is a function of distance from the aortic valve, compliance of blood vessels, and geometric considerations (arterial diameter and arterial branch points) 3. The dicrotic notch (the incisura) represents the closure of the aortic valve This indicates the start of diastole The pressure throughout diastole is also known as Peripheral Runoff 23 Arterial Sites Inaccuracy of waveform Lacks collateral circulation Adapted from Barash 24 Site Selection Arterial pressure waveforms change as the pressure wave moves from the aorta to the periphery. Distal to the Aortic Root: Higher SBP Steeper systolic upstroke Lower DBP Lower and later dicrotic notch, Wider pulse pressure Ex) the SBP in the radial artery is ~10-30mmHg higher than in the aorta, - DBP and MAP appear to be less affected These changes are the result of the decreased vessel diameter, decreased elasticity, & increased wave reflections due to vessel branch points 25 Analysis of the arterial pressure wave allows the practitioner to better comprehend the patient's heart function due to the pressure wave correlation with the cardiac cycle 26 Aortic stenosis Aortic regurgitation Normal Fixed obstruction = reduced stroke volume & slowed rate of ejection. Result: the waveform is small in amplitude, has a slow rising systolic upstroke, & a delayed peak Wide pulse pressure: sharp systolic rise and low diastolic pressure due to retrograde flow into the left ventricle. May have two systolic peaks (pulsus bisferiens): first peak resulting from antegrade ejection while the second wave is a reflection from the periphery 27 Pulse Pressure Variation Positive pressure ventilation causes variations in arterial pressure. Inspiration: Intrathoracic pressure is increased à decreases LV afterload & increases LV preload = Higher systemic pressure Exhalation: LV preload decreased due to inhalation decreased RV preload + pulmonary transit time = Lower systemic pressure 28 Pulse Pressure Variation By monitoring these cycles, the patient’s preload & fluid status responsiveness can be estimated Waveform peaks are compared between respiratory cycles and averaged over time PPV ≥ 13% indicates the patient would benefit from a fluid challenge 29 Continuous Cardiac Output Although blood pressure does not directly correlate with Cardiac Output, the arterial waveform can be analyzed with algorithms to provide further insight into cardiac function Windkessel Model: distensible arteries serve as a reservoir between phases of systole to diastole. Stroke Volume is calculated by comparing these changes in pressure v This is mathematically observed by measuring the area under the curve (Peripheral Runoff) 30 Goal-Directed Fluid Therapy GDFT = use of dynamic monitors to guide individualized patient fluid administration Historically, providers utilized fluid restrictive therapy or predictive fluid calculations Therapy is guided in order to minimize fluid shifts: Hypovolemia = Reduced end-organ perfusion vs Hypervolemia = Complications of edema & fluid overload 31 Central Venous Catheterization Indications: § Hemodynamic Monitoring (CVP) ± SvO2 as well § Rapid resuscitation § Infusion of caustic drugs, vasopressors, and TPN § Aspiration of air emboli § Insertion of transvenous pacer leads 32 Contraindications Coagulation Issues: Thrombolytic Therapy Anticoagulation Thrombus present in venous structure that you are cannulating Infection or burn directly over site of insertion Anatomic deformity or distortion over site of insertion Indwelling vascular implants (pacemaker) Higher risk patients: Chronic kidney disease Coagulopathies Obesity Respiratory compromise Prone positioning Patient Refusal 33 Insertion Site Selection Central venous catheters should be inserted on the SAME side as the pathologic lung when possible. If hemodynamic monitoring performed: right internal jugular vein as a first choice (provides the most direct path to the right atrium) The femoral site may provide less reliable hemodynamic monitoring. Examine the preferred site of insertion. If the area is inflamed, erythematous, or has significant deformation, an alternate site may be preferable. Consider surgical and positioning needs 34 Structure Advantages Disadvantages Internal Jugular Easy visualization with US Direct path to SVC/Rt. Atrium Least risk of DVT Small risk of infection Risk of arterial puncture ↓ patient comfort Subclavian Increased Comfort Least risk of infection Small risk of DVT Highest Risk of Pneumothorax Risk of Bleeding w/ difficulty providing compression Risk of long term stenosis Femoral Easily accessible Compressible if arterial puncture occurs Highest risk of infection DVT Risk Recommended only as last resort Internal Jugular Vein § Puncture at the apex of the Sedillot’s Triangle formed by the two heads of the sternocleidomastoid muscle Lateral to the thyroid cartilage § The IJ is typically larger, oval-shaped and compressible as compared to the carotid artery which is more round and noncompressible. Approx 1-2cm in depth Landmarks: q Angle of the mandible q Two heads of sternocleidomastoid muscle § Clavicle & Sternal Notch q Carotid artery q Trachea Adjacent anatomy: External jugular vein Phrenic and Vagus nerves 36 Left vs Right Anatomically, the right side provides a more direct route to the superior vena cava and is often larger than the left side Left Brachiocephalic Vein demonstrates anatomic variance [compared to right side] due to traversing the position of the heart, aorta, and left lung apex Angle of left brachiocephalic vein results in: Difficulty threading catheter through the jugular-subclavian junction Higher probability of SVC perforation 37 Left vs Right Additional consideration of Left IJ/SC includes potential damage to the thoracic duct The thoracic duct loops behind the IJ and enters the subclavian vein ~2 liters of chyle flows through the thoracic duct per day Thoracic duct injury can result from trauma or occlusion Any leak from this system results in significant morbidity due to secondarily causing respiratory distress as a result of a chylothorax v Damage to the right-sided lymphatic duct is rare 38 CVC Procedure 1. Timeout 2. Position Patient Turn head 15-30° Trendelenburg 10-20° 3. Initial ultrasound scan 4. Hand hygiene and don personal protective equipment 5. Prep & Drape patient in sterile fashion 6. Organize kit Connect & flush ports 7. Identify puncture site & localize with skin wheal 8. Insert introducer needle while aspirating until venous return 9. Thread the guidewire (observe EKG) 10. Remove introducer needle 11. Confirm guidewire placement using ultrasound Long axis view 12. Create a skin incision/nick 13. Thread the dilator over guidewire into subQ (do NOT hub) 14. Remove dilator 15. Thread central catheter 16. Remove guidewire 17. Aspirate, flush, & cap each lumen 18. Clean and secure catheter 19. Confirm placement via x-ray 39 CVC Procedure Steps 3. Initial Scan Place US transducer to identify structures in short axis to complete a pre-procedure risk assessment The internal jugular vein is typically located superficial and lateral to the carotid artery 40 CVC Procedure Steps 5. Prep/drape patient & equipment Skin Prep: Use scrubbing motion and move out from center Allow to dry: Chlorhexidine ≥ 90sec Betadine ≥ 3min 41 6. Organize Kit Introducer Needle Raulerson syringe Dilator J-Wire 42 CVC Procedure Steps 7. Identify insertion point at apex of Sedillot’s Triangle 8. Needle (bevel up) inserted at 30-45° towards ipsilateral nipple/iliac crest. Maintain continuous needle aspiration. Ultrasound advanced in coordination with tip of needle 43 9. Advance guidewire Seldinger Technique Raulerson syringe: insert J-wire through the opening in the distal part of plunger do NOT force guidewire at any time Should NOT advance past 15cm* Monitor for arrhythmias Maintain control of J-wire at all times 44 Pressure Manometry Analysis [optional] Equipment: Manometer/Extension tubing & Angiocath After Inserting the guidewire: 1. Remove the introducer needle: 2. Thread the conventional angiocath over the guidewire 3. Remove the guidewire. 4. Attach an extension tubing to the angiocath 5. Allow tubing to hang so that it fills 2/3 full with blood 6. Now hold the tubing straight up. Assess If the angiocath is in a vein: the column of blood will equilibrate about 3-10cm above the right atrium. Changes with respiration expected but should not be pulsatile. Blood coloration is a poor indicator of correct placement. If the angiocath is in an artery: the column of blood will continue to rise. 7. Disconnect tubing & Replace guidewire if in the vein 45 CVC Procedure Steps 11. Create a skin incision Slide blunt end of scapel along the guidewire and make a longitudinal incision ~0.5cm in depth 12. Insert dilator Use a circular, twisting motion, to progressively slide the dilator into the skin NEVER hub the dilator Remove the dilator & maintain control of the guidewire 46 15. Advancing central line catheter Catheter length is best estimated by measuring the distance from the needle insertion point and the third rib 47 16cm Average catheter length to the caval-atrial junction 15cm 21cm 19cm Right SC: 15 cm Right IJ: 16 cm Left SC: 19 cm Left IJ: 21 cm Femoral: 40cm 40cm 48 Peres Formula Modifiers Modified Peres Formula Height ÷ 10 [insertion site modifier] - 1cm - 2cm + 4cm + 2cm Catheter tip misplacement: Too short: increased venous thrombosis risk or potential migration into azygous or innominate vein. Too long: If in the right atrium, increased likelihood of arrhythmias and cardiac tamponade 49 50 Subclavian Vein The subclavian vein lies behind the clavicle, but is directly superficial of the first rib. It unites with the internal jugular vein and forms the innominate vein. While the subclavian approach provides consistent landmarks and has the lowest associated risk of infection, this approach should be avoided in patients with coagulation disorders due to the inability to compress the subclavian site effectively. This site is associated with the highest risk for pneumothorax Rarely, patients can also experience "pinch-off syndrome," in which devices in the subclavian vein become compressed between the clavicle and first rib. Landmarks include: Clavicle Sternocleidomastoid muscle Suprasternal notch Adjacent anatomy includes: Deltopectoral groove 1st rib Pleura 51 Infraclavicular Approach Identify landmarks of the sternal notch and the deltopectoral groove Patient is positioned 10-20° Trendelenburg. Head is maintained neutral. Needle insertion point is 1-2 cm inferior to the midpoint of the clavicle. Place needle bevel up while aiming toward the sternal notch using a 10-15° angle of insertion. Follow this trajectory while maintaining needle aspiration. Once venous return is confirmed, continue procedure steps as outlined previously 52 Infraclavicular - Ultrasound View above & below the clavicle to perform a survey scan of the subclavian vein. Observe vein trajectory from deltopectoral groove to superior aspect of clavicle. Note location of adjacent structures and artery Cannulation can be performed either in-plane or out Short axis view: Once needle tip is visualized, slide probe in unison to maintain visualization throughout procedure Long axis view: clavicle should be kept at edge of screen Guidewire placement and/or confirmation should be performed in a long axis view 53 Supraclavicular Approach Scan Sequence Initial Scan starts by identifying the Internal Jugular Vein Slide probe inferior to the junction of IJ and the Subclavian Vein Cannulation typically performed In-plane Pleura and Needle tip should be visualized at all times 54 Femoral Vein Typically reserved for emergency scenarios To remember the order of structures: NAVL pneumonic – NerveàArteryàVeinàLymphatics Landmarks: Locate the site for access by palpating the femoral artery’s pulse just distal to the inguinal Place the introducer needle 1-2cm inferior to the inguinal ligament and medial to the femoral artery. Needle is angled at 30-45° in a cephalad direction. Typical depth is 2-4cm. If access is being attempted during CPR, be aware the pulse you feel may be a venous pulse 55 CVP Waveform Upon proper placement of a central line, pressure waveform analysis can be performed CVP waveform illustrates: HR Conduction abnormalities Tricuspid valve function intrathoracic pressure variances right ventricular compliance The right atrial (RA) pressure waveform reflects both venous return and right ventricular end-diastolic pressure. Normal CVP waveform consists of three positive peaks (a,c,v) and two negative descents (x,y) in the RA waveform. 56 a wave Reflects atrial contraction Follows the P-wave on EKG Late diastole 57 c wave Reflects closure of the tricuspid valve Atrial relaxation + Isovolumetric right ventricular contraction + tricuspid valve closure à Tricuspid valve bulges back into the right atrium Occurs just after the QRS on EKG Early Systole 58 x descent “Systolic collapse in atrial pressure” Atrial relaxation + Ventricular contraction = Atrial pressure decline Mid-systolic on EKG 59 v wave Atrial pressure increase due filling of the atrium Tricuspid valve still closed Occurs just after the T-wave on EKG Late Systole 60 y descent “Diastolic collapse” due to passive filling As the tricuspid opens à blood flows from atrium to ventricle = Decrease in atrial pressure Early diastole 61 CVP Wave Mnemonic “a” wave: Atrial contraction “c” wave: tricuspid Closure and ventricular contraction “v” wave: Venous filling of atrium “x” descent: relaXation of atrium “y” descent: emptYing of atrium 62 CVP Waveform 63 Waveform Abnormalities Atrial Fibrillation Tricuspid Stenosis, RV hypertrophy 64 Waveform Abnormalities Tricuspid Regurgitation 65 CVP CVP is approximate to right atrial pressures which can be used to estimate right ventricular preload Suggestive of blood volume and right-sided cardiac function Normal value in a spontaneously breathing pt 5-10 mmHg Rises ~3-5mmHg during mechanical ventilation Dependent on functional ventricles, lack of valvular disease, physiologic vasculature - Poor correlation to patient fluid status - Fluid therapy should ideally involve monitoring trends and including other measurements 66 Complications Insertion-related complications: Arterial puncture Air or thrombus embolism Arrhythmias Hematoma Pneumothorax/hemothorax/hydrothorax/ chylothorax Thoracic duct injury Cardiac perforation or cardiac tamponade Nerve injury Insertion complication rates increased by: Practitioner proficiency Number of needle passes BMI >30 or PV>PA) allows for uninterrupted blood flow and continuous communication with left heart cardiac pressures. Increases in alveolar pressure or decreases in perfusion can convert Zone III conditions in the lung to Zone I or Zone II. Absent a & v-waves indicates incorrect positioning into zones I or II 90 West Lung Zones Pa = arterial pressure PV = venous pressure P(A) = Alveolar pressure End-expiratory intrathoracic pressures most closely approximate atmospheric pressure - Therefore Measurements should be taken at end of expiration to minimize transmural pulmonary and pericardial pressures influence on CVP or PAWP 91 PA Catheter Risks Complications: PA rupture Endocarditis Pulmonary valve damage Dysrhythmias (ventricular tach/fib, RBBB) Pulmonary infarction Thrombogenesis Hemorrhage Pneumothorax Air embolism Sepsis Contraindications: DO NOT float PAC in patients with left bundle branch block if RBBB occurs you risk a complete heart block Endocarditis Tricuspid regurgitation: technically difficult Concern for Coagulopathies 92 Placement Confirmation The tip of the PAC should be: ≤ 2cm of the Hila (lung roots) ≤ 2cm of the cardiac silhouette And ≤ 4-5cm from midline Left Hilum Right Hilum 93 Big nope 94 Thermodilution Gold standard method of measuring cardiac output via the Stewart-Hamilton equation Practitioner injects a cold solution which travels from the cavoatrial junction (proximal port) to the pulmonary artery where the temperature change is measure by a thermistor Calculation of cardiac output is possible by plotting a time-temperature curve 95 Thermodilution Thermodilution cardiac output estimates can vary with: Intrathoracic pressures - measurements at end expiration reduce this variability Ensuring that the rate of injection and the volume are constant (provider variability) *Should average 3 separate measurements* 96 Thermodilution 97 Thermodilution 98 Other methods of measuring cardiac output: Arterial waveform analysis (previously discussed) Dye Dilution Transpulmonary dilution Esophageal doppler CO2/O2 measurement (Fick’s Equation) Thoracic impedance Echocardiography 99 Esophageal Doppler Esophageal probe is inserted ~35cm and aimed anterior Incisors to 3rd rib (T5-T6) Uses ultrasound to measure blood flow velocity in the descending aorta Blood cells reflect frequency relative to direction and speed of blood flow SV is calculated in order to calculate cardiac output requires a constant for distance 100 Echocardiography Transesophageal Echocardiography uses include: Determining the source of hemodynamic instability (myocardial ischemia, heart failure, valvular disorders, hypovolemia, and tamponade) Quantitative measurements of hemodynamic parameters (SV, CO, and intracavitary pressures) Visualizing pericardial (valves, aorta, possible shunts) 101 TEE Probe Movements 102 TTE TTE provides rapid and less invasive cardiac visualization to provide a Qualitative assessment of hemodynamic status and anatomic aberrations: Pericardial Effusion Hypovolemia Chamber dysfunction Emboli Pneumothorax http://pie.med.utoronto.ca/tte/TTE_content/focus.html 103 US / PoCUS Sonography is now considered standard of care for central line placement. It has recently garnered increased interest to aid in early detection and diagnosis of common central line placement complications. Emerging techniques now allow for additional confirmation of correct placement of the central line catheter 1. Obtain transthoracic view 2. saline flushed via the distal lumen of the CVC while visualizing the right atrium. 3. Positive Sign: If microbubbles/turbulence can be observed ≤ 2 seconds of the flush 104 US / PoCUS 105 SvO2 Fiberoptic channels allow for recording of reflection spectrophotometry to determine venous oximetry (SvO2) SvO2 reflects the balance between cardiac output, hemoglobin, arterial oxygen delivery (DO2) and oxygen consumption (VO2) Modified Fick Equation: SvO2 = SaO2 – [VO2 / (cardiac output × Hgb × 1.34)] ScvO2 does not include returning coronary venous blood, which has a low saturation of ~25% Saturation changes often precede hemodynamic fluctuations and may therefore be a useful early warning sign of hemodynamic compromise Normal Range: 65-75% 106 Informed Consent Informed Consent for procedures should involve a discussion with the patient that includes benefits (why catheterization is needed), risks (complications), and alternatives In emergency scenarios, patient next-of-kin and/or power of attorney should be consulted In the event of patient refusal: thorough documentation of associated risks should be noted Recommendations are to supplement generic institution consent forms Interpreters and translated consent forms/educational material must be utilized 107 Billing Billing for anesthesia-related procedures usually involves factors for procedure, anesthesia time, facility fees, and [sometimes] management Billing documentation may require additional notations: Medical necessity Health risks/diagnosis Provider credentials Supporting proof of procedure CMS billing codes 108 Umbilical Venous Catheter Provides central access in urgent resuscitative scenarios Umbilical vein catheterization procedure: [Patent 10-14 days] 1. Prep & drape the umbilical stump in sterile fashion, 2. Place a tie around the base of the umbilicus with a half knot Tight enough to control bleeding but loose enough to permit catheter passage. 3. Cut the umbilical cord about ~2 cm above the skin. 4. Locate the umbilical vein - typically cephalad at the 12 o’clock position 5. insert a preflushed catheter into the vein approximately 2-5 cm & check for blood return. 6. secure the catheter or advance catheter to inferior vena cava. 7. Confirm with x-ray or ultrasound Typically 5-8 French Low umbilical venous length: 2-5cm Length to inferior vena cava: 6-12cm Ductus venosus still present in neonates so that blood flow can go from umbilical vein to IVC while bypassing the liver Contraindications: Omphalocele Gastroschisis Omphalitis Peritonitis Necrotizing enterocolitis 109 Additional Resources Supplemental Readings: Miller, Chap 36 & 37 Morgan & Mikhail, Chap 5 Nagelhout, Chap 17 Subclavian Vein Ultrasound: https://www.youtube.com/watch?v=IBmbc1ak5fY&list=PL2AGl6lzXJTMg5SNRnBRl2kmKUxbRB1_ IJ Ultrasound: https://www.youtube.com/watch?v=eesN9rGoXFM&t=83s Radial Artery Ultrasound: https://www.youtube.com/watch?v=uHfeyAYiWOc&t=99s SvO2: https://www.ncbi.nlm.nih.gov/books/NBK539835/?report=classic Square knot: https://www.google.com/search?q=square+knot+suturing&rlz=1C1GCEU_enUS1017US1017&oq=square+knot +suturing&aqs=chrome..69i57j0i512j0i22i30j0i390l3.4542j0j15&sourceid=chrome&ie=UTF8#fpstate=ive&vld=cid:98e61622,vid:BEYWsNYEt78 https://www.google.com/search?q=square+knot+suturing&rlz=1C1GCEU_enUS1017US1017&oq=square+knot +suturing&aqs=chrome..69i57j0i512j0i22i30j0i390l3.4542j0j15&sourceid=chrome&ie=UTF-8#kpvalbx=_00zAYrHFue5qtsPhbigsAE_43 110

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