Adrenal blood flow and secretory effects of adrenergic receptor stimulation.

To evaluate effects of adrenergic receptor stimulation on regional adrenal blood flow and secretion, pentobarbital-anesthetized dogs (n = 5-6/group) received the beta-agonist isoproterenol (group I), the alpha 1-agonist phenylephrine (group II), or the alpha 2-agonist dexmedetomidine (group III). Measurements of adrenal cortical (CQ) and medullary (MQ) blood flow (radiolabeled microspheres) and catecholamine secretion were made before and during agonist infusion. Isoproterenol increased catecholamine secretion but had no direct effect on MQ or CQ. In contrast, phenylephrine increased MQ and CQ four- and twofold, respectively. Dexmedetomidine had no effect on MQ or catecholamine secretion. To evaluate whether blood flow effects of phenylephrine were due to increases in mean arterial blood pressure (MAP) or related to activation of alpha 1-adrenergic receptors, two additional groups of animals received phenylephrine; group IV had MAP maintained at baseline by controlled hemorrhage into a pressurized bottle; group V received prazosin before phenylephrine. Prevention of MAP increase did not prevent the vasodilation response to phenylephrine, but it was completely blocked by prazosin. Canine adrenal homogenates incubated with the alpha 1-adrenoceptor ligand, 125I-labeled 2-[beta-(4-hydroxyphenyl)ethlaminomethyl]tetralone, demonstrated specific and saturable binding, supporting the presence of alpha 1-adrenergic receptors. We conclude that increases in MQ and CQ elicited by phenylephrine appear to be due to alpha 1-receptor stimulation. The mechanism responsible for this vasodilation is not known.

Negative chronotropic factor in patients with fungemia.

OBJECTIVE: To study the effect of serum from patients with fungemia and control patients on sinoatrial node function. DESIGN: Prospective, observational study. SETTING: Surgical ICU in a university hospital. PATIENTS: Fourteen patients with fungemia and 14 control patients. MEASUREMENTS AND MAIN RESULTS: Serum samples from all patients were assayed in an in vitro sinus node preparation. Serum samples from 11 (78%) of the 14 fungemic patients caused a decrease in sinus node activity, while serum samples from only one (7%) of 14 control patients caused slowing of the sinus node. CONCLUSIONS: Serum from many patients with fungemia causes slowing of an in vitro sinus node preparation. This in vitro finding may explain bradyarrhythmias seen clinically in the setting of fungemia.

The role of anesthetic induction agents and neuromuscular blockade in the endotracheal intubation of trauma victims.

Management of extensive trauma often requires immediate tracheal intubation and mechanical ventilation. The role of anesthetic induction agents and neuromuscular blockade in the airway management of the trauma victim is disputed. To better define the role of these agents in the acute management of trauma, the adult trauma registry of The Johns Hopkins Hospital was reviewed to determine the frequency of use of these agents in acute airway management and to assess the effect of these agents on the incidence of complications. Ninety-seven patients were reviewed. Thirty-one patients were intubated because of cardiopulmonary arrest. Of the remaining 66 patients, oral intubation was initially attempted in 54. When drugs were used to facilitate intubation (n = 36), the success rate was 92 per cent on the first attempt, and 100 per cent on the second attempt. When drugs were not used (n = 18), 39 per cent could not be intubated (n = 7). Subsequent drug administration resulted in successful intubation of five of seven of these patients. Nasal intubation (no drugs) was only successful in 60 per cent of the patients (50 per cent on first attempt). Four patients required a cricothyrotomy. Two other patients vomited, and one patient aspirated. None of these patients received drugs prior to the first attempt at intubation. No hemodynamic or neurologic complications, related to relaxant or induction agent use, were observed. These findings suggest that oral intubation with drugs to facilitate airway management is most likely to result in successful intubation on the first attempt and that drug use in the trauma setting is safe.

Hyperadrenergic states.

OBJECTIVE: To review the physiologic and pathophysiologic hyperadrenergic states and the pharmacologic use of sympathomimetic agents. DATA SOURCES: Pharmacologic and physiologic studies in experimental animals and humans. DATA EXTRACTION/SYNTHESIS: Plasma catecholamines are increased in a variety of clinical situations. Following major injury, catecholamines act to support vital organ perfusion and mobilize fuel substrates. However, with surgical trauma and during acute medical illnesses, such as myocardial infarction, catecholamine-induced physiologic changes can interact with underlying disease processes to result in clinically significant complications. Exogenous catecholamines are used to treat a variety of medical conditions, including anaphylaxis and various shock states. Available sympathomimetic agents differ in their availability to stimulate different subpopulations of adrenergic receptors. These differences permit the astute clinician to achieve specific physiologic end-points. Finally, plasma catecholamines are increased in patients with pheochromocytoma. This latter condition provides insights into the long-term effects of catecholamine excess. CONCLUSIONS: Based on knowledge of the pharmacology of sympathomimetic agents and the physiologic consequences of adrenergic receptor stimulation, it is possible to prevent undesirable catecholamine effects and to utilize these agents to achieve desired therapeutic goals.

The incidence of awareness, and amnesia for perioperative events, after cardiac surgery with lorazepam and fentanyl anesthesia.

One hundred patients (mean age 59 +/- 10 years) were premedicated with morphine, 0.15 mg/kg, and scopolamine, 0.008 mg/kg. Anesthesia was induced with lorazepam, 50 microg/kg, followed by fentanyl, 50 microg/kg, oxygen and pancuronium, 0.15 mg/kg. Isoflurane was given for short periods before and after cardiopulmonary bypass to 57 patients when hypertension was uncontrolled by addition of fentanyl and/or nitroglycerin. Morphine was used as the sole sedative postoperatively. Patients were interviewed following discharge from the surgical intensive care unit to assess the incidence of operative awareness, and to assess amnesia for events occurring during four preoperative and two postoperative periods of the patients' hospital stay. During three preoperative periods (day of admission, evening before, and morning before operation), 1%, 3%, and 2% of patients had complete amnesia, and 19%, 41%, and 31% had partial amnesia of events. Fifty-five percent of patients exhibited complete, and 34% of patients exhibited partial amnesia to events occurring in the preinduction period. Two patients reported intraoperative awareness (noises, conversation) occurring at the end of the anesthetic. In the two postoperative periods (morning of the day after surgery and intensive care stay), 9% and 15% of patients had complete, and 35% and 47% of patients exhibited partial amnesia. Amnesia was statistically significantly greater in patients over 60 years of age in the preinduction period. Duration of cardiopulmonary bypass did not affect the incidence of amnesia.