ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Previous reports have attributed increased carotid blood flow to lung ventilation during CPR. This study was undertaken to determine whether PEEP (20 torr airway pressure) or increased frequency of ventilation (3:1) improved arterial pressure, flow, and blood gases. Thirty-three domestic pigs were studied using three protocols (standard 5:1 CPR, 5:1 CPR plus PEEP, 3:1 CPR) distributed such that comparisons could be made between groups as well as within the same pig. For intrapig comparisons, Po2was significantly improved (p< 0.05) by PEEP (ΔPo2= 9.7 ± 13.0 torr). Pco2was significantly less (p< 0.005) for 3:1 compared to 5:1 (ΔPco2= −4.7 ± 2.1 torr). For group comparisons, Po2was 55.5 ± 12.9 torr without and 70.1 ± 16.3 torr with PEEP (p< 0.025). For 3:1, Po2was 66.3 ± 11.6 torr that was greater (p< 0.10) than for 5:1. When ventilation was temporarily halted, phasic changes in flow with ventilation were replaced by nearly constant flow approximately equal to maximal flow when ventilation was provided. PEEP and more frequent ventilation improved blood oxygenation but at the expense of carotid blood flow.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

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). On repeated trials in the same animal, ventilation pressures from 10–50 cm of H2O were tested in randomized sequence, while the technique of chest compression was held constant. Arterial blood gases immediately after resuscitation were monitored. Increasing ventilation pressure had surprisingly little effect on cardiac output during CPR, although blood gases were profoundly altered. For ventilation pressures of 10, 20, 30, 40, and 50 cm of H2O, producing mean tidal volumes 23, 38, 61, 83, and 94 ml/kg; cardiac output remained nearly constant, averaging 21,25,23,26, and 24 ml/minμkg. Corresponding mean postresuscitation pH was 7.24, 7.41, 7.51, 7.56, and 7.53; Pco2was 41, 26, 18, 16, and 15 torr. 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.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

The authors have developed a method for measurement of cardiac output during CPR with ventricular fibrillation. The method avoids the problems encountered when conventional techniques are used under the conditions of very low cardiac output. The method consists of injecting 5% saline as the indicator into the left ventricular and detecting its appearance in the descending aorta by withdrawing aortic blood through an electrically calibrated conductivity cell. The adequacy of indicator mixing has been verified by obtaining dilutions curves simultaneously from the brachial and femoral arteries. Cardiac output can be determined even when output is as low as 7 ml/minμkg during CPR with ventricular fibrillation. Repeated determinations can be made as often as every min. This method offers promise as a practical research tool which can also be used with dye indicators.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

To determine differences in regional blood flow during CPR versus normal cardiac function, the authors measured regional blood flow to several organs in 19 pentobarbital-anesthetized dogs (6–12 kg). Regional blood flow was measured during sinus rhythm in five dogs and during electrically induced ventricular fibrillation with CPR in the other 14 dogs. Regional blood flow and cardiac output were measured using radioactively labeled polystyrene microspheres of 15 ± 3 μ diameter, injected into the left ventricle. Adequacy of microsphere mixing at low cardiac outputs was verified by comparing flow rates to paired organs. Cardiac output was 175 ml/kgμmin during sinus rhythm versus 47 ml/kgμmin during CPR. Flow to all organs sampled was less during CPR, but the relative decrease varied widely. The ratios of regional blood flow during CPR to regional blood flow during sinus rhythm were 90% for brain, 35% for heart, 15% for kidneys, 17% for adrenal glands, 14% for pancreas, 3% for spleen, and 33% for small intestine. These results provide baseline values for regional blood flow during CPR which can be used to evaluate alternative CPR techniques and/or drugs which may improve perfusion of vital organs during CPR.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

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. After 30 sec of CPR, either 0.9% saline vehicle or 50 μg/kg of epinephrine, phenylephrine, or isoproterenol was administered through a central venous catheter. One min later, microspheres were injected into the left ventricle. After 250 sec of CPR, the ventricles were defibrillated electrically. Between each drug injection, 20-min recovery periods were interposed. Each dog received all three drugs and saline according to a predetermined sequence. After saline, epinephrine, phenylephrine, and isoproterenol treatment, respectively, cardiac output averaged 392, 319, 255, and 475 ml/min; brain blood flow averaged 37, 54, 29, and 28 ml/min; coronary blood flow averaged 25, 79, 26, and 15 ml/min; and kidney blood flow averaged 44, 4, 16, and 29 ml/min. Epinephrine improved blood flow to the brain, probably because of its α-adrenergic activity. Epinephrine improved blood flow to the heart during CPR much more than the other agents, probably because of its combined α- and β-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.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID

摘要:

Maintenance of arterial pressure and consciousness by vigorous coughing during ventricular fibrillation has been previously documented. Observations in 4 additional patients with unstable rhythms and in fibrillating dogs confirm that coughing: (1) produces an arterial pulse; (2) produces opening of the aortic valve; (3) generates forward blood flow; and (4) can maintain consciousness during circulatory arrest. The authors speculate that cough-induced systemic perfusion results from compression of the pulmonary vascular beds by a rise in intrathoracic pressure, the left heart acting only as a one-way conduit to the lower pressure extrathoracic vascular outlets. Receht data suggest that conventional CPR likewise produces blood flow by compression of the pulmonary vascular blood pool, and not by cardiac compression as previously thought.

ISSN:0090-3493    

出版商:OVID    

年代:1980

数据来源: OVID