Towards noncommutative quantum reality.

The implications of the physical theory of quantum mechanics on the question of realism is much a subject of sustaining interest, while the background questions among physicists on how to think about all the theoretical notion and 'interpretation' of the theory remains controversial. Through a careful analysis of the theoretical notions with the help of modern mathematical perspectives, we give here a picture of quantum mechanics, as the basic theory for 'nonrelativistic' particle dynamics, that can be seen as being as much about the physical reality as classical mechanics itself. The key is to fully embrace the noncommutativity of the theory and see it as a notion about the reality of physical quantities. Quantum reality is then just a noncommutative version of the classical reality.

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.

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.

Ventricular fibrillation in a swine model of acute pediatric asphyxial cardiac arrest.

STUDY OBJECTIVE: To determine cardiac rhythms in a swine model of acute pediatric asphyxial cardiac arrest. DESIGN: Prospective electrocardiographic evaluation of 36 piglets. SETTING: University hospital laboratory. INTERVENTION: Piglets were acutely asphyxiated by endotracheal tube clamping until 10 min after loss of aortic pulsations. Resuscitative efforts were then provided. RESULTS: None of the animals had ventricular fibrillation (VF) when loss of aortic pulsations occurred (11 +/- 2 min after clamping). Fourteen of the 36 piglets exhibited VF during the asphyxial insult. VF converted to asystole in four piglets prior to resuscitation. Immediately prior to resuscitation, VF occurred in 10 piglets, asystole in 19 piglets, and bradyarrhythmias in seven piglets. CONCLUSION: VF occurs frequently in this piglet model of prolonged asphyxial cardiac arrest, consistent with recent observations in pediatric prehospital cardiac arrests. VF occurred late in the asphyxial process.

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.

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.

Airway management and ventilation during CPR.

In this porcine model of fibrillatory cardiac arrest (Table 1), ventilation during basic life support does not improve 24-hour survival or neurological outcome compared to chest compressions alone when advanced life support is provided within 15 minutes of arrest. Bystander CPR can save lives, but is usually not offered, at least in part, because of reluctance to perform mouth-to-mouth ventilation. If chest compressions alone are similarly effective and more acceptable compared to chest compressions and mouth-to-mouth ventilation, the simpler technique may result in more lives saved.

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.

Cardiac arrest and monitoring.

Initial assessment to determine pulselessness, monitoring the status of the patient, and the effectiveness of resuscitation efforts are integral parts of cardiopulmonary resuscitation. This article focuses on aspects of monitoring during cardiopulmonary resuscitation: electrocardiography and assessment of the adequacy of chest compressions.

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.

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.

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.

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)

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.

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.

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.