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Biomedical subjects

S A Stayer

Publications and source records attributed to S A Stayer.

26 records · Page 2Linked to original sources
PubMed1994

The metabolic effects of surface cooling neonates prior to cardiac surgery.

Neonates undergoing cardiac surgery at The Children's Hospital of Philadelphia frequently developed metabolic acidemia as they passively cooled prior to the start of cardiopulmonary bypass. This study was performed in an attempt to identify the mechanism for this acidemia. After receiving an initial dose of fentanyl (10 micrograms/kg) and pancuronium, 22 neonates were randomly assigned to maintain normothermia by active warming (Group I), or to permit passive cooling (Group II) before surgery. Arterial blood samples were obtained prior to, and at 10 and 45 min after entering the operating room for the analysis of pH, gas tensions, lactate, pyruvate, plasma free fatty acids, acetoacetate, beta-hydroxybutyrate, total CO2, and glucose concentrations. In the last 11 patients studied, the observation period was extended to 75 min at which time another arterial blood sample was obtained. There was a steady decrease in heart rate as the Group II patients cooled; however, arterial blood pressure did not change in either group. There were no changes in blood values measured in Group I neonates. In the Group II patients, there was a progressive decline in calculated base excess, total CO2, and an increase in serum lactate as the patients cooled. The metabolic acidemia that develops in neonates represents lactate accumulation as a consequence of surface cooling prior to surgery and the institution of cardiopulmonary bypass. Whether lactate accumulates as a result of anaerobic metabolism in underperfused tissue beds or reduced hepatic clearance could not be distinguished in this study. Since neither clinically significant hemodynamic changes nor differences in outcome were found between the two groups, the authors believe this mild lactic acidemia is inconsequential and does not require therapy.

Acidosis↗
PubMed1993

Tracheal tube leak test--is there inter-observer agreement?

Although the leak test is recommended as a method of assessing the appropriate size of uncuffed endotracheal tubes for use in children, the reproducibility of this test has not been validated. Patients from newborn to ten years of age requiring tracheal intubation for elective surgery were studied. The endotracheal tube size was calculated using the formula: (age + 16) divided by 4 for patients > or = two years of age and at the discretion of the attending anaesthetist for patients < two years of age. After the induction of anaesthesia and administration of a nondepolarizing muscle relaxant, the patient's trachea was intubated and mid-tracheal placement was confirmed. Two of the three staff anaesthetists participating in the study assessed the leak pressure consecutively. Each participant performed a single leak determination. The leak pressure was determined as follows: the patient was supine with the head in a neutral position, fresh gas flowed into the breathing circuit at 5 L.min-1, a stethoscope was placed on the skin over the larynx and the pressure relief valve was completely closed. Pressure slowly increased in the breathing circuit until an audible leak occurred around the tracheal tube. The inter-observer difference was calculated in 212 patients. The absolute value of the difference between that of two observers increased as the mean leak pressure increased. However, the variation between observers expressed as a percent of the absolute measurement remained constant. An average variance in measurement of 38% was found at both low and high leak pressures. In conclusion, we found considerable variation between two experienced observers in assessing leak pressures.(ABSTRACT TRUNCATED AT 250 WORDS)

Auscultation↗
PubMedDate not supplied

Bacterial endocarditis prophylaxis: what is recommended and what is practiced?

STUDY OBJECTIVE: To determine how often pediatric anesthesiologists follow the American Heart Association (AHA) recommendations for the administration of prophylactic antibiotics to prevent bacterial endocarditis (BE). DESIGN: Questionnaires mailed to all members of the Society for Pediatric Anesthesia regarding their use of antibiotics to prevent BE. SETTING: Anesthesia department at a university-affiliated children's hospital. MEASUREMENTS AND MAIN RESULTS: 898 questionnaires were mailed, and 465 questionnaires were returned, yielding a response rate of 52%. When anesthesiologists administer BE prophylaxis intravenously (IV), they perform an inhalation anesthetic 76% of the time prior to establishing IV access. Ninety percent of the respondents stated that if administration of antibiotics occurs after a mask induction, they do not delay incision or instrumentation for 30 minutes. Therefore, respondents do not follow AHA recommendations for BE prophylaxis 55% of the time. Of the 465 respondents, only 4 recalled pediatric patients who developed perioperative BE. CONCLUSIONS: The majority of anesthesiologists responding to this survey routinely do not follow the current AHA recommendations for BE prophylaxis when caring for children. Since there are no studies demonstrating that administering antibiotics 30 minutes prior to invasive procedures is more effective than administering antibiotics immediately prior to invasive procedures, it may be appropriate to follow a time sequence that is more comfortable and convenient for pediatric patients. We believe that a reconsideration of the current AHA recommendations for BE prophylaxis is warranted.

American Heart Association↗