Critical care medicine
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Critical care medicine · Mar 1980
Influence of adrenergic drugs upon vital organ perfusion during CPR.
To determine whether adrenergic drugs administered during CPR alter the distribution of artificial cardiac output, the authors measured regional blood flow and cardiac output using radioactive microspheres in 12 dogs. Ventricular fibrillation was induced electrically and CPR was immediately begun with a mechanical chest compressor and ventilator (Thumper) at 60 compressions/min, with a ventilation: compression ratio of 1:5, a compression duration of 0.5 sec, and a ventilation pressure of 20 cm H2O. Compression force was sufficient to develop 40--50 mm Hg peak intraesophageal pressure. ⋯ Epinephrine improved blood flow to the heart during CPR much more than the other agents, probably because of its combined alpha- and beta-adrenergic activity. This effect may explain its superiority in restoring circulation after prolonged arrest and resuscitation. Isoproterenol should not be used in CPR because it shunts blood away from vital organs.
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Critical care medicine · Mar 1980
A comparison of standard, "MAST"-augmented, and open-chest CPR in dogs. A preliminary investigation.
Hemodynamic, respiratory, and cerebral variables during 2 h of standard external CPR were studied in 5 dogs. In an additional 12 dogs, possible augmentation of these variables by Military Anti-Shock Trousers (MAST) was evaluated. In 9 dogs, external and internal cardiac massage were compared. ⋯ A switch to open-chest (internal) cardiac massage (OCCM) after 2 h of external CPR significantly increased arterial and perfusion pressures (decreased venous pressures) and more than doubled CCABF; and resulted in a return of EEG activity and pupillary constriction. Prolonged standard CPR, and to a lesser extent MAST-augmented CPR, seem unlikely to maintain adequate oxygen transport for vital organ systems viability, particularly the brain. OCCM might better sustain viability.
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Critical care medicine · Mar 1980
INfluence of interposed ventilation pressure upon artificial cardiac output during cardiopulmonary resuscitation in dogs.
This study was conducted to determine the effects of high pressure interposed ventilations during cardiopulmonary resuscitation (CPR). Cardiac output was measured by a modified indicator dilution technique in eight anesthetized, intubated mongrel dogs. Positive pressure ventilations (12/min, 80% O2) were interposed after every five chest compressions (performed at 62/min) by a mechanical chest compressor (Thumper). ⋯ The postresuscitation arterial oxygen tension was greater than 100 torr at all ventilation pressures except 10 cm of H2O. Interposed ventilations of pressure and volume more than adequate to prevent acidosis during CPR did not impair artificial cardiac output. If anything, cardiac output was slightly improved by more forceful ventilation.
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Critical care medicine · Feb 1980
Case ReportsUse of volume loading to obtain preferred levels of PEEP. A preliminary study.
Hemodynamic and oxygen transport measurements were made with successive increments of positive end-expiratory pressure (PEEP) in 14 episodes of ARDS in 11 patients who had normal or slightly increased blood volumes. "Preferred" or optimal PEEP was defined as the PEEP value associated with the greatest VO2 that did not compromise pulmonary function as determined by shunting (Qs/Qt). The preferred PEEP averaged 10.7 +/- 2.7 (SD) cm H2O in the patients who had appreciable reduction in cardiac index (CI) by the time this level of PEEP was reached. ⋯ The final preferred PEEP in these patients averaged 14.1 +/- 3.6 (SD) cm H2O. The authors conclude that the titration of PEEP as well as fluid therapy may be used to maximize VO2 in patients with early shock lung.