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Biomedical subjects

C W Otto

Publications and source records attributed to C W Otto.

At least 19 recordsLinked to original sources
PubMed1992

A study of chest compression rates during cardiopulmonary resuscitation in humans. The importance of rate-directed chest compressions.

A prospective, cross-over trial was performed comparing two different rates of precordial compression using end-tidal carbon dioxide as an indicator of the efficacy of cardiopulmonary resuscitation in 23 adult patients. A second purpose of this study was to determine the effect of audio-prompted, rate-directed chest compressions on the end-tidal carbon dioxide concentrations during cardiopulmonary resuscitation. Patients with cardiac arrest received external chest compressions, initially in the usual fashion without rate direction and then with rhythmic audiotones for rate direction at either 80 compressions per minute or 120 compressions per minute. Nineteen of 23 patients had higher end-tidal carbon dioxide levels at the compression rate of 120 per minute. The mean end-tidal carbon dioxide level during compressions of 120 per minute was 15.0 +/- 1.8 mm Hg, slightly but significantly higher than the mean level of 13.0 +/- 1.8 mm Hg at a compression rate of 80 per minute. However, end-tidal carbon dioxide levels increased rather dramatically when audiotones were used to guide the rate of chest compressions. Mean end-tidal carbon dioxide concentration was 8.7 +/- 1.2 mm Hg during standard cardiopulmonary resuscitation immediately before audio-prompted, rate-directed chest compression and increased to 14.0 +/- 1.3 mm Hg after the first 60 seconds of audible tones directing compressions. Using end-tidal carbon dioxide as an indicator of cardiopulmonary resuscitation efficacy, we conclude that audible rate guidance during chest compressions may improve cardiopulmonary resuscitation performance.

Aged↗
PubMed1990

The role of bicarbonate and fluid loading in improving resuscitation from prolonged cardiac arrest with rapid manual chest compression CPR.

Rapid manual chest compression (120 compressions/min) CPR has been shown to improve hemodynamics and survival when compared with standard CPR (60 compressions/min) in a canine model of prolonged cardiac arrest. The study showing improved survival with rapid manual CPR empirically included treatment with bicarbonate and initial fluid loading. To determine the role of bicarbonate and fluid loading in the success of rapid manual chest compression CPR, 31 mongrel dogs were studied. After instrumentation with micromanometer-tipped catheters to measure aortic and right atrial pressures, the animals were assigned sequentially to three treatment groups. Group A underwent rapid manual chest compressions at 120 compressions/min, bicarbonate treatment, and initial fluid loading. Group B underwent rapid manual compressions at 120 compressions/min without bicarbonate or fluid loading. Group C underwent standard CPR at 80 compressions/min with bicarbonate and fluid loading. After 30 minutes of ventricular fibrillation, defibrillation was attempted. Seven of 11 dogs in group A survived 24 hours. None of the animals in group B resuscitated or survived. Three of the ten dogs in group C survived 24 hours. Survival with rapid manual CPR without bicarbonate and initial fluid loading was significantly less than when these interventions were used (P less than .01). To examine the separate contribution of bicarbonate and fluid therapy, two additional groups of animals were studied. Fourteen animals (group D) received rapid manual CPR with bicarbonate therapy, and 12 (group E) received rapid manual CPR with fluid loading only.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

End-tidal carbon dioxide monitoring during cardiopulmonary resuscitation. A prognostic indicator for survival.

The effectiveness of ongoing cardiopulmonary resuscitation efforts is difficult to evaluate. Recent studies suggest that carbon dioxide excretion may be a useful noninvasive indicator of resuscitation from cardiac arrest. A prospective clinical study was done to determine whether end-tidal carbon dioxide monitoring during cardiopulmonary resuscitation could be used as a prognostic indicator of resuscitation and survival. Thirty-five cardiac arrests in 34 patients were monitored with capnometry during cardiopulmonary resuscitation during a 1-year period. Nine patients who were successfully resuscitated had higher average end-tidal carbon dioxide partial pressures during cardiopulmonary resuscitation than 26 patients who could not be resuscitated (15 +/- 4 vs 7 +/- 5 mm Hg). The 3 patients who survived to leave the hospital had a higher average end-tidal carbon dioxide partial pressure than the 32 nonsurvivors (17 +/- 6 vs 8 +/- 5 mm Hg). All 9 patients who were successfully resuscitated had an average end-tidal carbon dioxide partial pressure of 10 mm Hg or greater. No patient with an average end-tidal carbon dioxide partial pressure of less than 10 mm Hg was resuscitated. Data from this prospective clinical trial indicate that findings from end-tidal carbon dioxide monitoring during cardiopulmonary resuscitation are correlated with resuscitation from and survival of cardiac arrest.

Blood Gas Monitoring, Transcutaneous↗
PubMed1988

Acid-base balance in a canine model of cardiac arrest.

Our study was performed to determine the pattern of arterial, venous, and cerebral spinal fluid (CSF) acidosis in a canine model of cardiac arrest and resuscitation; and the effect of bicarbonate treatment on arterial, venous, and CSF acidosis. Animals were instrumented to sample arterial blood, mixed venous blood, and CSF through a cisternal catheter. Following six minutes of ventricular fibrillation, manual CPR efforts were begun and continued for 30 minutes of cardiac arrest. Arterial, mixed venous, and CS fluids were sampled at baseline, six, 12, 18, 24, 27, and 30 minutes. Ten experimental dogs received sodium bicarbonate (2 mEq/kg) at 20 minutes of cardiac arrest, while ten animals in the control group received no alkali treatment. The experimental group showed a significantly higher arterial (7.79 +/- 0.20 vs 7.46 +/- 0.16 at 30 minutes) and venous pH (7.34 +/- 0.12 vs 7.19 +/- 0.10 at 24 minutes) following bicarbonate administration. This higher pH occurred despite a concomitant increase in arterial (31 +/- 10 vs 19 +/- 9 mm Hg at 27 minutes; 31 +/- 9 vs 10 +/- 8 at 30 minutes) and venous (104 +/- 30 vs 63 +/- 10 mm Hg at 24 minutes) pCO2. CSF analysis showed a gradually worsening acidosis. However, CSF pH (7.12 +/- 0.14 vs 7.16 +/- 0.23 at 30 minutes) and pCO2 were not significantly changed by the administration of bicarbonate.

Acidosis↗
PubMed1987

Effect of alterations in frequency, inspiratory time, and airway pressure on gas exchange during high frequency jet ventilation in dogs with normal lungs.

High frequency jet ventilation (HFJV) is becoming increasingly useful for providing respiratory support in patients with normal lungs during operative procedures, and also has been advocated as a technique for ventilating patients during cardiopulmonary resuscitation. We studied the effect of frequency, percent inspiratory time (I/E ratio), peak airway pressure, and airway pressure difference (peak-PEEP) during HFJV as operational variables on the efficacy of gas exchange in dogs with normal lungs. We observed that at a constant peak airway pressure and percent inspiratory time, PaCO2 generally increases as frequency rises above 100/min. In contrast, PaCO2 generally decreases as percent inspiratory time is reduced at a constant frequency and peak airway pressure. In addition, increasing peak airway pressure and airway pressure difference are associated with lower levels of PaCO2. Arterial oxygenation was adversely affected by frequencies above 300/min, but was otherwise not influenced by alterations in frequency, percent inspiratory time, or airway pressure.

Animals↗
PubMed1987

Comparison of epinephrine and phenylephrine for resuscitation and neurologic outcome of cardiac arrest in dogs.

A study was done comparing resuscitability and 24-hour neurologic outcome in fibrillating dogs that were treated with either phenylephrine (a primary alpha agonist) or epinephrine. Ventricular fibrillation was induced electrically in 18 dogs. After three minutes, standard CPR was instituted using a mechanical resuscitator. Dogs were given phenylephrine or epinephrine at nine minutes and defibrillation was attempted at 12 minutes. Dogs underwent hemodynamic monitoring and pharmacologic support, if necessary, for an additional 90 minutes. At four, eight, 12, and 24 hours, a standard neurologic examination was performed and deficit scores were assigned by an observer blinded to the drug given. Fourteen of the 18 dogs were resuscitated. There were no statistically significant differences in the epinephrine- or phenylephrine-treated groups with regard to number of animals resuscitated, time and interventions required for resuscitation, initial cardiac rhythm post resuscitation, or occurrence of ventricular fibrillation during resuscitation. No differences were found in arterial, central venous, or myocardial perfusion pressures during CPR. Phenylephrine-treated dogs tended to have higher mean pressures in the critical care period (15 to 30 minutes), although this was not significant. Total neurologic deficit scores were 127.8 +/- 83.8 for the phenylephrine-treated group and 129.4 +/- 87.4 for the epinephrine group. No significant differences were found in the level of consciousness, cranial nerve function, motor skills, or general behavior scores. We conclude that there is no difference in neurologic or cardiovascular outcome when phenylephrine is compared to epinephrine in a canine model of cardiac arrest and cardiopulmonary resuscitation.

Animals↗
PubMed1986

Cardiovascular pharmacology. II: The use of catecholamines, pressor agents, digitalis, and corticosteroids in CPR and emergency cardiac care.

The Cardiovascular Pharmacology II panel met during the AHA National Conference on Standards and Guidelines for CPR and emergency cardiac care to consider the use of catecholamines, pressor agents, digitalis, and corticosteroids during advanced cardiac life support. During cardiac arrest, catecholamines and pressor agents have been shown to improve the rate of success of resuscitation. The useful properties of these drugs are mediated by strong alpha-adrenergic stimulation resulting in improved coronary perfusion. beta-Adrenergic stimulation during cardiac arrest is unimportant for resuscitation and potentially harmful. Studies have not demonstrated a difference between mixed agonists and alpha-agonists with respect to overall outcome. Consequently, the panel recommended that epinephrine continue to be the primary vasopressor for use during cardiac arrest. For cardiovascular support in the hemodynamically unstable patient, the panel recommended that drugs be chosen for specific pharmacologic actions that will allow the needed physiologic manipulation guided by objective hemodynamic measurements. The panel found that digitalis preparations and corticosteroids have very limited use in emergency cardiac care.

Adrenal Cortex Hormones↗
PubMed1986

Ventilatory management in the critically ill.

A basic understanding of respiratory physiology and ventilator-patient interaction is critical for the initiation of ventilatory support and management of the ventilated patient. A brief review of these subjects is incorporated in this outline of the approach to the patient requiring mechanical ventilation.

Acute Disease↗
PubMed1985

Effect of epinephrine on defibrillation in ischemic ventricular fibrillation.

Epinephrine is thought to improve the success of defibrillation with countershock therapy. However, a recent study failed to show any effect of epinephrine in dogs with normal coronary arteries undergoing electrically-induced ventricular fibrillation (VF). In the current study, the effects of epinephrine were examined in dogs with coronary occlusion undergoing both spontaneous and electrically-induced fibrillation. Forty pentobarbital-anesthetized dogs were prepared by placing snares around the circumflex and left anterior descending coronary arteries. Fibrillation and subsequent resuscitation were carried out with one coronary artery occluded. Dogs were randomly allocated so that half of the animals underwent spontaneous fibrillation and half were electrically fibrillated. In addition, half received epinephrine (1 mg) during resuscitation and half received normal saline solution (1 ml). After 3 minutes of cardiac arrest, cardiopulmonary resuscitation (CPR) was begun, and 30 seconds later epinephrine or saline were injected. One minute later defibrillation was attempted using successive stored energy doses of 1, 2, 4, 8, 16, and 32 J/kg. Delivered energy and transthoracic impedance were measured for each countershock. Successful defibrillation was defined as conversion to any rhythm other than VF or ventricular tachycardia that degenerated in VF within 10 seconds. No other drugs were given during resuscitation. Neither the type of fibrillation (electrically-induced versus spontaneous) or drug therapy (epinephrine versus placebo) had a significant effect on the incidence of defibrillation or the energy necessary for successful defibrillation. Epinephrine did significantly increase the incidence of resuscitation.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

The role of epinephrine in CPR: a reappraisal.

Epinephrine is the recommended drug for use in resuscitation from all types of cardiac arrest. Experimental evidence has shown that the actions of epinephrine important for the restoration of spontaneous circulation are mediated by the alpha-adrenergic properties. The beta-adrenergic effects do not aid restoration of spontaneous circulation, nor do they aid defibrillation; however, beta-adrenergic stimulation does increase the oxygen consumption of the fibrillating myocardium, a potentially deleterious effect. The important factor in restoring spontaneous circulation appears to be development of adequate coronary blood flow by increasing coronary perfusion pressure (aortic diastolic minus right atrial pressure). Aortic diastolic pressure can be increased by any potent alpha-adrenergic agonist. Because phenylephrine and methoxamine do not have significant beta-adrenergic actions, they should be considered as alternatives to epinephrine for aid in restoring spontaneous circulation. Once spontaneous circulation is restored, alpha-and/or beta-adrenergic agonists may be needed for circulatory support. Which drugs will provide the best longterm survival has not been established.

Epinephrine↗
PubMed1984

Airway movement in dogs during high-frequency jet ventilation.

Cine tantalum bronchograms were recorded from 7 pentobarbital-anesthetized dogs during spontaneous ventilation (SV), high-frequency jet ventilation (HFJV) at 3 frequencies, and intermittent positive-pressure ventilation (IPPV) at 3 combinations of tidal volume (VT) and rate. During SV and the 3 IPPV conditions, the percent inspiratory increase in the diameter of airways greater than 3 mm was the same as in airways less than 3 mm. With HFJV, the percent increase in the diameter of airways greater than 3 mm was twice that of smaller airways. Increases in airway diameter are proportional to transmural, and hence intraluminal airway pressure. These data, therefore, indicate that the contribution of intraluminal pressure changes to intrapulmonary gas transport in small airways during HFJV is less than with either SV or IPPV, and that mechanisms responsible for intrapulmonary gas transport in small conducting airways during HFJV are different than those associated with either SV or IPPV.

Air Movements↗
PubMed1984

Comparison of high-frequency jet ventilation with conventional mechanical ventilation in saline-lavaged rabbits.

A surfactant-depletion lung-injury model was produced in 37 New Zealand white rabbits by saline lavage. During the next 2 to 3 h, rabbits were ventilated with conventional mechanical ventilation (CMV, group 1), high-frequency jet ventilation (HFJV, group 2), or CMV for 1 h followed by HFJV for 2 h (CMV/HFJV, group 3). Survival until planned termination of the protocol was 56%, 77%, and 63% in groups 1, 2 and 3, respectively. Causes of early demise were usually pneumothorax or metabolic acidosis. There were no statistically significant differences among the groups with respect to survival, incidence of pneumothorax or metabolic acidosis. Arterial oxygenation was more efficient with HFJV (group 2) (P[A-a]O2 = 372 +/- 51 torr [mean +/- SE] at 2 h) than with CMV (group 1) (P[A-a]O2 = 512 +/- 18 torr at 2 h, p less than .01). Furthermore, oxygen gas exchange in 3 of 5 group 3 rabbits improved after institution of HFJV. In contrast to previous findings with high-frequency oscillation (HFO), there were no qualitative histologic differences between lungs ventilated with HFJV vs. CMV. Thus, although HFJV produced more efficient gas exchange in this model, it did not improve pulmonary pathology. HFO may be preferable to HFJV in infant respiratory distress syndrome.

Animals↗
PubMed1983

Spontaneous ischemic ventricular fibrillation in dogs: a new model for the study of cardiopulmonary resuscitation.

Most sudden cardiac deaths in man are associated with events causing myocardial ischemia and only 40-60% of these patients are successfully resuscitated. Further progress in reducing the mortality from such events will depend on a better understanding of the interventions used during CPR. Animal models currently used for the study of CPR do not involve myocardial ischemia. A new model of cardiac arrest (spontaneous ischemic ventricular fibrillation) in closed-chest dogs resembles more closely the events occurring in man. Initial controlled, randomized studies of the model demonstrate that it responds to resuscitation in a manner similar to human resuscitation. Further study of this model during CPR may lead to changes in patient care which will improve survival from episodes of sudden cardiac death.

Animals↗