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Physiology Directed CPR

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Physiology Directed CPR

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Physiology Directed CPR

  1. 1. Physiology directed CPR Dr Kerry Gomes 16/8/2018
  2. 2. Cardiac Arrest is NOT a diagnosis  It’s the final pathway for all pathologies leading to death  Important to consider underlying pathologies - ?reversible causes  Presumed cardiac  Structural – CAD, cardiomyopathies, WPW, genetic  Electrical – long QT, Brugada  Informed suspicion  Electrolyte, toxic, metabolic, hypo/hyperthermia  Mechanical interference – PE, tamponade  Aortic dissection  Respiratory arrest
  3. 3. Physiology of circulation during closed chest compressions  CCC and recoil of chest generate a proportion of cardiac output by two means –  Cardiac pump model  Thoracic pump model  Cardiac output  Severely depressed during CPR (10-33% prearrest values in exp. animals)  Majority directed to organs above the diaphragm  brain blood flow 50-90%  Cardiac blood flow 20-50%  Lower extremeties and abdominal visera <5%  Flow to brain and heart improved by vasopressors
  4. 4. Assessing circulation adequacy during CPR  Coronary Perfusion  Occurs primarily during diastolic phase  Myocardial blood flow is optimum during CCC when aortic diastolic pressure >40mmHg  Vascular pressures below critical levels associated with poor outcomes  Exhaled CO2  Excellent non-invasive indicator of effective resus  After intubation CO2 levels are primarily dependant on blood flow  During CPR if blood flow starts to increase, more alveoli are perfused and etCO2 levels rise  Spontaneous circulation etCO2 value < 40mmHg  etCO2 corresponds with coronary perfusion pressure, cardiac output and survival
  5. 5. Haemodynamically directed CPR
  6. 6. Studies  Patient-centric blood pressure-targeted cardiopulmonary resuscitation improves survival from cardiac arrest.  Sutton et al. Am J Respir Crit Care Med. 2014 Dec 1;190(11):1255-62  20 female 3-month-old swine  After 7 minutes of asphyxia (ETT clamped), VF was induced  randomly received 10 minutes period of CPR before defibrillation  blood pressure-targeted care consisting of titration of compression depth to a systolic blood pressure of 100 mm Hg and vasopressors to a coronary perfusion pressure greater than 20 mm Hg (BP care)  American Heart Association Guideline care consisting of depth of 51 mm with standard advanced cardiac life support epinephrine dosing (Guideline care).  The 24-hour survival was higher in the BP care group (8 of 10) compared with Guideline care (0 of 10); P = 0.001.  Coronary perfusion pressure was higher in the BP care group (+8.5 mm Hg; vs 3.9-13.0 mm Hg; P < 0.01)  Blood pressure-targeted CPR improves 24-hour survival compared with optimal American Heart Association care in a porcine model of asphyxia-associated VF cardiac arrest.
  7. 7. Studies  A quantitative comparison of physiologic indicators of cardiopulmonary resuscitation quality: Diastolic blood pressure versus end-tidal carbon dioxide  R.W. Morgan et al. Resuscitation 104 (2016) 6–11  Two models of cardiac arrest (primary ventricular fibrillation [VF] and asphyxia-associated VF)  3-month old swine received either standard AHA guideline-based CPR or patient-centric, BP-guided CPR.  Mean values of DBP and ETCO2 in the final 2 min before the first defibrillation attempt were compared  60 animals, 37 (61.7%) survived to 45 min.  DBP was higher in survivors than in non-survivors (40.6 ± 1.8 mmHg vs. 25.9 ± 2.4 mmHg; p < 0.001)  ETCO2 was not different (30.0 ± 1.5 mmHg vs. 32.5 ± 1.8 mmHg; p = 0.30  In both primary and asphyxia-associated VF porcine models of cardiac arrest, DBP discriminates survivors from non-survivors better than ETCO2. Failure to attain a DBP >34 mmHg during CPR is highly predictive of non-survival.
  8. 8. ABP and CVP  Supine CVP similar to pressures in femoral artery  In supine patient arterial BP ≡ CVP  Femoral artery cannulation  Continuous pressure monitoring  Access to ABGs  Direct feedback from the intraarterial pressure waveform  Improved CCC technique
  9. 9. Assess HD goals  CVP <10mmHG  Rapid fluid bolus  thinking is that CVP <10 = volume down, so giving volume improves venous return  Interpediance threshold device / pulmonary vasodilator  Study by fire department – gave 2L crystalloid to arrest pt = florid pulm oedema  CVP >20mmHG  Consider echo to evaluate possible cause  PE -> tPA  PTx/effusion -> drain it  Sepsis -> inotropes
  10. 10. Assess HD goals  Diastolic BP <35-40mmHg  Consider more frequent adrenaline or adrenaline infusion  Consider vasopressin  Systolic BP <100mmHg  Optimise hand position - by improving impulse -> get better sBP on ejection  Use echo to check  Change depth and rate  increased depth leads to increased ejection and higher sBP  Increased rate to 130, but may inversely decrease depth
  11. 11. “next cycle”  Assess vent and O2 (if HD goals met)  ABGs  If pH <7.2, paO2 < 70 - > increase vent rate 50% (8 -> 16/18)  Does VBG represent venous pooling  Focusing on oxygenation  Current trail doing ABG and VBG – ABG better thus far  NIRS – near infrared spectroscopy (pulse Ox)  If >50% and paO2 >200 -> decrease FiO2 50%

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