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Biomedical subjects

C W Otto

Publications and source records attributed to C W Otto.

48 records · Page 3Linked to original sources
PubMed1981

Mechanism of action of epinephrine in resuscitation from asphyxial arrest.

To determine the relative importance of the alpha and beta adrenergic effects of epinephrine in resuscitation, 32 dogs were studied in four groups. Group A (alpha blocked) received phenoxybenzamine, 70 mg/kg; group B (beta blocked), propranolol 5 mg/kg; group C (alpha and beta blocked) both drugs; and group D (control), no drug. After this treatment and 5 min of asphyxial arrest, all animals received closed chest cardiac massage (CCCM), artificial ventilation (AR), and epinephrine, 1 mg, iv. Resumption of spontaneous circulation occurred with the following frequency: group A, 0/8; group B, 6/8, group C, 0/8, group D, 7/8. The difference in successful resuscitation of the alpha blocked animals and the not alpha blocked animals is statistically significant (P less than or equal to 0.01). It is concluded that the efficacy of epinephrine in aiding resumption of spontaneous circulation from asphyxial arrest is due to alpha adrenergic receptor stimulation and that beta receptor stimulation is not important in determining outcome.

Animals↗
PubMed1981

Comparison of dopamine, dobutamine, and epinephrine in CPR.

Two new catecholamines, dopamine and dobutamine, have found widespread use for cardiovascular support. The relative efficacy of these drugs in aiding resuscitation from cardiopulmonary arrest is unknown. Dogs were subjected to either asphyxial or fibrillatory cardiac arrest. Resuscitation was attempted with artificial ventilation, closed chest cardiac massage, and one of four iv drug protocols: dopamine, 40 mg; epinephrine, 1 mg; dobutamine, 50 mg; or no drug. The incidence of successful resuscitation from both asphyxial and fibrillatory arrest was significantly greater in groups receiving dopamine or epinephrine than in groups receiving dobutamine or no drug. There was no difference in success between the dopamine and epinephrine groups. The authors conclude that, in dogs, dopamine is a useful adjunct to CPR because of its alpha-adrenergic stimulating activity at high doses. Dobutamine does not appear to be of value as the initial therapy of cardiac arrest. If the response in man is similar to that in dogs, dopamine may provide an alternative to epinephrine during CPR.

Animals↗
PubMed1981

Acute cardiovascular effects of dimethylsulfoxide.

Dimethylsulfoxide (DMSO) has been advocated as a central nervous system (CNS) protectant against ischemia and trauma. The present study was performed to evaluate acute cardiovascular effects of DMSO which might complicate the clinical treatment of CNS compromised patients. Intravenously administered DMSO in doses which reportedly provide CNS protection, 2 g/kg, were infused in 6 dogs; hemodynamic variables were measured and compared to infusion of equal volumes of 0.9% sodium chloride. Immediately after infusion, DMSO caused increases in cardiac index, heart rate, pulmonary capillary wedge pressures (WP), and pulmonary arterial (systolic, mean, and diastolic) pressures which were significantly greater than changes induced by saline. DMSO decreased systematic diastolic pressure and systemic vascular resistance at the end of infusion. Most DMSO induced changes returned toward pre-infusion values 10 min after the end of infusion. These results suggest transient DMSO effects different from equal volumes of saline, possibly due to hyperosmotic expansion of plasma volume. A decrease in systemic vascular resistances was also observed. Although neither CNS production, intracranial pressure or blood flow were studied, these data suggest that DMSO used for CNS protection would not have adverse acute hemodynamic consequences. This may be particularly relevant in traumatized, hypovolemic patients.

Animals↗
PubMed1980

Influence of time and therapy on ventricular defibrillation in dogs.

Factors that may influence energy requirements for ventricular defibrillation include the duration of fibrillation and the mode of resuscitation. The present study assesses the effect of these influences on the energy needed for defibrillation. Dogs were anesthetized, and arterial blood pressure and Lead II of the ECG were continuously recorded. Ventricular fibrillation was electrically induced in each dog for a period of 1, 3, 5, or 9 min. Three resuscitation techniques were evaluated: precountershock artificial ventilation (AV) and closed-chest cardiac massage (CCCM); precountershock AV/CCCM and epinephrine, 1 mg IV; and countershock without preliminary AV/CCCM or epinephrine. Each animal was shocked with successive doses of 1, 2, 4, and 8 J/kg, ceasing when either electrical conversion occurred or after the maximum dose had been delivered. If defibrillation was unaccompanied by resumption of spontaneous circulation (systolic pressure greater than 60 mm Hg greater than 2 min), AV/CCCM was administered for 1 min. In general, the incidence of defibrillation was inversely proportional to the duration of fibrillation. Epinephrine had no significant effect on the energy dose needed for conversion. After 2 min of fibrillation, however, epinephrine became increasingly important for restoration of circulation. The technique of immediate countershock was effective for episodes of fibrillation limited to approximately 3 min. Regardless of therapy, for intervals of fibrillation of up to 6 min, Gompertz data curves indicated that a delivered energy of 4--5 J/kg is the approximate energy dose associated with the maximum achievable incidence of defibrillation within the limits of this experimental protocol.

Animals↗
PubMed1979

Relative importance of alpha and beta adrenergic receptors during resuscitation.

Successful resuscitation from cardiac arrest in the asphyxiated dog model has been ascribed to the use of artificial ventilation, closed chest cardiac massage, and administration of a vasopressor. Controversy remains over whether the most commonly employed vasopressor, epinephrine, exerts its effects primarily by elevating diastolic pressure and reestablishing coronary flow, or by exciting cardiac pacemaker cells and enhancing myocardial contractility. To observe pure alpha and beta adrenergic receptor influences during resuscitation, three groups (alpha-blocked, beta-blocked, unblocked) of dogs were studied. beta-blocked dogs resuscitated with phenylephrine and unblocked dogs resuscitated with epinephrine experienced 100% successful resumption of spontaneous circulation after 5 min of asphyxia-induced arrest. Only 27% of alpha-blocked animals resuscitated with isoproterenol were successfully revived. The appearance of the ECG during cardiac arrest and resuscitation could in no way be used to predict the outcome of resuscitation attempts. Results suggest that, initially, alpha receptor stimulation with concomitant diastolic pressure elevation is more important to the success of resuscitation than beta receptor stimulation.

Animals↗
PubMed1976

Total spinal anesthesia: a rare complication of intrathoracic intercostal nerve block.

Total spinal anesthesia following intrathoracic intercostal nerve blocks with bupivacaine performed for postoperative pain relief during thoracotomy is described. Possible mechanisms for this complication include: (1) inadvertent placement of the needle through an intervertebral foramen, (2) puncture of a long dural cuff, and (3) intraneural injection with central spread. Recognition of this potential complication is important, and facilities for proper support must be available.

Bupivacaine↗