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Biomedical subjects

H J Heyman

Publications and source records attributed to H J Heyman.

18 recordsLinked to original sources
PubMed1995

Preoperative pregnancy testing in ambulatory surgery. Incidence and impact of positive results.

BACKGROUND: The incidence of unrecognized early pregnancy and its influence on the surgical and anesthetic course in patients presenting for elective ambulatory surgery have not been previously determined. The current study was designed to determine the incidence of unrecognized pregnancy in women presenting for ambulatory surgery. In addition, it examined how discovery of the pregnancy altered the anesthetic or surgical course. METHODS: In a prospective study over a 1-yr period, all women of childbearing potential (defined as menstruating women without prior hysterectomy or tubal ligation) were preoperatively evaluated and tested for urine or serum human chorionic gonadotropin, to determine unrecognized pregnancy. If a pregnancy was detected, the disposition of the surgical procedure and the effect on the surgical and anesthetic management was recorded. RESULTS: Of 2,056 women of childbearing potential presenting for ambulatory surgery, testing revealed 7 previously unrecognized pregnancies, an incidence of 0.3%. Included among these patients were two patients scheduled to undergo fertility procedures. On learning the test result and even before being advised of available options, all patients elected to cancel or postpone the surgical procedure. CONCLUSIONS: The incidence of previously unrecognized pregnancy in menstruating women presenting for ambulatory, nonobstetric surgery was 0.3%. The knowledge of a positive test resulted in cancellation or postponement of the operative procedure. Patient desire for cancellation was the main determining factor in each case.

Ambulatory Surgical Procedures↗
PubMed1991

Hemodynamic responses to endotracheal extubation after coronary artery bypass grafting.

After coronary artery bypass grafting (CABG) surgery, patients may remain at risk for myocardial ischemia and infarction and ventricular dysrhythmias. The hemodynamic responses to endotracheal extubation and the efficacy of intravenous lidocaine pretreatment were studied after CABG surgery and overnight mechanical ventilation. Twenty-five patients were divided into two groups: group 1 (n = 13) patients who had tracheal extubation after pretreatment with a placebo; group 2 patients who received lidocaine (1 mg/kg IV) before tracheal extubation. Hemodynamic data, electrocardiographic tracings, and arterial blood gases were obtained before tracheal extubation, during suctioning, and 1, 5, and 20 min after tracheal extubation. Group 1 patients displayed significant increases in heart rate, arterial blood pressure, rate-pressure product, right atrial pressure, and cardiac index during suctioning and within 1 min of tracheal extubation, returning to preextubation level by 5 min. There were no significant changes in pulmonary and systemic resistance indices. Hemodynamic changes in group 2 patients were similar to those in group 1. Both in the absence and presence of lidocaine, tracheal extubation caused hemodynamic responses that were small in magnitude and brief in duration. These responses were not associated with electrocardiographic or enzymatic evidence of myocardial ischemia or infarction, or with ventricular dysrhythmias. Compared with the well-documented hemodynamic responses to tracheal intubation, we found that extubation of the trachea after CABG surgery was associated with less pronounced responses. This may be related to avoidance of laryngoscopy and possibly accommodation to the endo-tracheal tube. These modest hemodynamic responses of extubation of the trachea after CABG surgery were not modified by intravenous lidocaine.

Coronary Artery Bypass↗
PubMed1983

Sodium thiosulfate disposition in humans: relation to sodium nitroprusside toxicity.

Thiosulfate concentrations and pharmacokinetics were studied in relation to sodium nitroprusside before, during, and after anesthesia. Normal thiosulfate concentrations were 1.13 +/- 0.11 mg/dl and 0.28 +/- 0.02 mg/dl in plasma and urine, respectively. Cholecystectomy patients had similar concentrations during surgery, with bile thiosulfate concentration of 13.72 +/- 2.95 mg/dl. Fasting patients and children had significantly higher plasma and urine thiosulfate concentrations. Over 99% of endogenous filtered thiosulfate was reabsorbed by the kidney in the average case. Coronary bypass patients had decreased plasma thiosulfate levels and increased excretion postoperatively. Disappearance of injected thiosulfate was biphasic; the distribution phase was dependent on the initial rate of injection, and the elimination phase depended on extracellular fluid turnover and renal excretion. Cholecystectomy patients on diuretics had a markedly increased rate of excretion, 56% within 100 min, versus normal subjects who excreted less than 50% in up to 18 h. In children, plasma thiosulfate did not change significantly, while blood cyanide concentration increased significantly during sodium nitroprusside administration and surgery. Thiosulfate did not change during recovery while cyanide decreased. Normal production of thiosulfate in humans may be limited; hence, continuous thiosulfate infusion may be required during sodium nitroprusside administration.

Adolescent↗
PubMed1980

Cyanide antidotes and methods of their administration in dogs: a comparative study.

To test the efficacies of various antidotes to cyanide (CN) poisoning, the lethal dose of cyanide in dogs was estimated during constant infusion of potassium cyanide at a rate of 0.1 mg/kg/min. Additionally, arterial blood pressure, right ventricular pressure, heart rate, electrocardiogram, blood-gas and pH values, and whole blood and tissue CN concentrations were measured. The lethal dose in animals whose lungs were ventilated with room air was 2.4 +/- .2 mg/kg (mean +/- SE), while the whole-blood CN concentration was 438 +/- 40 micrograms/dl and the gracilis muscle concentration was 2.0 +/- .3 micrograms/100 g. A low dose of vitamin B12a (100 mg/kg), an infusion of thiosulfate (12 mg/kg/h), or ventilation with 100 per cent O2 increased the amount of CN needed to cause death. A bolus injection of nitrite (5 mg/kg), thiosulfate (150 mg/kg), or cysteine (450 mg/kg) increased the the protection from lethality even further. Protection against CN administration for the total 150-min period of observation was provided by a bolus injection plus a constant infusion of nitrite (5 mg/kg bolus plus 5 mg/kg/h). thiosulfate (30 mg/kg bolus plus 60 mg/kg/h), or vitamin B12a (50 mg/kg bolus plus 100 mg/kg/h). However, nitrite infusion produced high levels of methemoglobin 7.2 +/- 1.1 g/dl, while vitamin B12a infusion and cysteine injection, at the stated doses, did not prevent cyanide-induced circulatory failure. Therefore, thiosulfate appears to be the most effective and safest prophylactic agent against cyanide toxicity in dogs.

Amygdalin↗
PubMed1975

Cardiovascular effects of intraperitoneal insufflation with carbon dioxide and nitrous oxide in the dog.

Cardiovascular changes caused by intraperitoneal insufflation with CO2 or N2O were measured in 15 mongrel dogs. Moderate progressive increases in intra-abdominal pressure (to 40 mm Hg) with either gas produced increases in mean arterial, right atrial, pleural, and femoral-vein pressures. Cardiac output and inferior vena caval flow were momentarily increased following the commencement of insufflation. However, both flows decreased precipitously as insufflation pressure was increased. At an intra-abdominal pressure of 40 mm Hg cardiac output and inferior vena caval flow were reduced more than 60 per cent in most cases. Peripheral resistance increased by approximately 200 per cent. Upon sudden release of abdominal pressure cardiac output and inferior vana caval flow increased but then returned to pre-insufflation values within seconds. Directly measured right atrial pressure increased with increasing insufflation pressure, but calculated transmural right atrial pressure decreased with the increase in intra-abdominal pressure. Insufflation with CO2 produced significant increases in PaCO2. However, cardiostimulatory effects due to elevated blood CO2 levels were not seen. The data from this study indicate that intraperitoneal insufflation produces serious hemodynamic alterations which are manifested by low cardiac output and elevated total peripheral resistance. In addition, directly measured right atrial pressure cannot be used clinically as an indicator of venous return to the heart since it reflects a composite of pleural and intra-abdominal insufflation pressure. (Key words: Anesthetics, gases, nitrous oxide; Carbon dioxide, intraperitoneal; Surgery, intraperitoneal insufflation; Heart, function, intraperitoneal insufflation.).

Acid-Base Equilibrium↗
PubMedDate not supplied

Enflurane anesthesia for surgical removal of pheochromocytoma.

Four cases describing the use of enflurane as the main anesthetic during surgical removal of pheochromocytoma (PCC) are presented and the preoperative preparation and intraoperative management of the patients are discussed. Serum levels of epinephrine and norepinephrine were measured in 3 of the reported cases. Intraoperative values were extremely elevated during tumor manipulation, but there was only 1 minor episode of arrhythmias. Criteria for choosing anesthetic agents for surgical removal of PCC are outlined. The authors conclude from their experience and that of others that enflurane is as safe and effective an anesthetic as any now available for PCC excision.

Adult↗