Resuscitation
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Comparative Study
Early volume expansion during cardiopulmonary resuscitation.
To determine if hemodynamic parameters, return of spontaneous circulation (ROSC), and short term survival are improved by volume expansion during resuscitation from ventricular fibrillation cardiac arrest. ⋯ Early volume expansion with epinephrine during HICPR does not improve CPP, rate of ROSC, or rate of short term survival from VF arrest in this porcine model. HSD volume expansion does improve systemic hemodynamics after ROSC with increased CPP, AoSBP, and AoDBP. Improved tissue perfusion in Group B animals after ROSC is suggested by a decreased pH and increased PCO2 presumably secondary to enhanced mobilization of lactate and PCO2 from tissues.
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Return of spontaneous circulation with CPR is a function of coronary perfusion pressure, which is determined by vasomotor tone and the force of compression. Vasomotor tone is affected by the relative stimulation of arterial vasoconstricting and vasorelaxing receptors by vasoactive substances. We measured the plasma levels of the endogenous vasoactive peptides arginine vasopressin (AVP) angiotensin II (ANG-II) and atrial natriuretic peptide (ANP) during cardiac arrest and resuscitation. ⋯ There were significant increases in the levels of these endogenous vasoactive peptides. This reflects the neuroendocrine response to global ischemia and CPR reperfusion. Plasma levels of these peptides may effect the vital organ perfusion pressures, response to exogenous vasopressors, and outcome of resuscitative efforts. Future therapies may be directed at enhancing or blocking the effect of these peptides so as to optimize perfusion pressure which is one of the principle determinants of outcome during CPR.
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Epinephrine is used to increase coronary perfusion pressure and improve myocardial blood flow during cardiac arrest. Alternative vasopressors may have hemodynamic advantages over epinephrine. The purpose of this investigation was to test the effect of the vasopressor angiotensin II on myocardial blood flow in a swine model of cardiac arrest. ⋯ This fell to 15.1 +/- 19.9 with CPR alone, and rose to 66.9 +/- 69.8 following angiotensin II administration (P = 0.04; by two tailed T-test). Myocardial blood flow following ROSC further increased to 212.6 +/- 58.0. Angiotensin II in a dose of 50 micrograms/kg significantly increases myocardial blood flow in this model of cardiac arrest.
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This investigation was designed to test the hypothesis that active compression-decompression resuscitation is able to independently provide improved levels of minute ventilation when compared to high-impulse manual cardiopulmonary resuscitation (CPR). Eight adult beagles (10-15 kg) were studied after induction of ventricular fibrillation. Single 1-min CPR trials were performed while arterial blood gases and minute ventilation were monitored. ⋯ We conclude that ACD CPR provides improved levels of minute ventilation when compared to high-impulse manual CPR in this canine model of cardiac arrest. Improved minute ventilation may contribute to the mechanism of improved cardiopulmonary hemodynamics reported in previous investigations of ACD CPR. Further investigation is warranted to determine the effects of ACD CPR on pulmonary ventilation in human subjects after cardiac arrest.
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Comparative Study Clinical Trial
Effects of induced hypothermia in patients with septic adult respiratory distress syndrome.
To test the hypothesis that treatment with hypothermia affects the course of overwhelming acute respiratory failure associated with sepsis. ⋯ This study suggests that hypothermia was effective in improving oxygenation and survival in patients with severe ARDS associated with sepsis, even though VO2 was unchanged.