Circulation
-
Current basic life support (BLS) protocols do not address the physiologic effects of accidental hypothermia in prehospital care. The extreme levels of bradycardia, bradypnea, and peripheral vasoconstriction that often accompany profound hypothermia may complicate the accurate diagnosis of cardiopulmonary arrest in the unmonitored patient. ⋯ This dilemma had led to disagreement among clinicians and researchers in hypothermia about prehospital care protocols for the severely hypothermic patient. This article reviews the controversy and recommends the application of a normal BLS protocol to hypothermic patients presenting in apparent cardiopulmonary arrest.
-
The addition of interposed abdominal compressions (IACs) to otherwise standard CPR enhances artificial circulation both in anesthetized dogs with ventricular fibrillation and in electrical models of the circulation that demonstrate fundamental mechanisms generating flow. Manual abdominal compressions cause both central aortic and central venous pressure pulses but, because of differences in venous and arterial capacitance, the former are usually greater than the latter. ⋯ However, no study has demonstrated that IAC-CPR improves either short- or long-term survival after cardiac arrest in man. Accordingly, the method remains experimental and cannot be recommended for basic life support at the present time.
-
The finding that blood flow during external chest compression may be due to increased intrathoracic pressure, and the subsequent reporting of increased carotid blood flow with simultaneous ventilation and chest compression or with abdominal binding during CPR ignited a flurry of investigations into alternative approaches to CPR. A number of alterations of the conventional CPR technique were proposed, many resulting in improved hemodynamics when compared with standard CPR techniques in the same subject. However, some of the proposed methods increased cerebral blood flow but decreased myocardial perfusion. ⋯ Not all studies support the conclusion that blood flow during closed-chest compression is secondary to increased intrathoracic pressure. It is probable that in man there is a spectrum. In some individuals the predominant mechanism of blood flow during CPR may be cardiac and/or vascular compression, and in others flow may be secondary to an increased intrathoracic pressure.
-
Three forms of treatment are available for patients with paroxysmal supraventricular tachycardia (PSVT): nonpharmacologic, pharmacologic, and electrical. Nonpharmacologic treatments increase vagal tone and include the traditional carotid sinus massage and Valsalva maneuver as well as head-down tilt, activation of the diving reflex, and use of the pneumatic antishock garment. ⋯ Patients with antegrade accessory pathway conduction (such as those with Wolff-Parkinson-White syndrome) and a history of atrial fibrillation should be treated with intravenous procainamide if they are hemodynamically stable and with synchronized electrical countershock if they are hemodynamically unstable. Synchronized electrical countershock is the treatment of choice for hemodynamically unstable patients.