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Biomedical subjects

D J Steward

Publications and source records attributed to D J Steward.

At least 37 records · Page 2Linked to original sources
PubMed1991

Tracheal extubation in children: halothane versus isoflurane, anesthetized versus awake.

The authors compared the incidence of respiratory complications and arterial hemoglobin desaturation during emergence from anesthesia in children whose tracheas were extubated while they were anesthetized or after they were awake and to whom halothane or isoflurane had been administered. One hundred children 1-4 yr of age undergoing minor urologic surgery were studied. After a standard induction technique, patients were randomized to receive either isoflurane or halothane. In 50 patients tracheal extubation was performed while they were breathing 2 MAC of either halothane or isoflurane in 100% oxygen. The remaining 50 patients received 2 MAC (volatile agent plus nitrous oxide) during the operation, but tracheal extubation was delayed until they were awake. A blinded observer recorded the incidence of respiratory complications and continuously measured hemoglobin saturation for 15 min after extubation. When tracheal extubation occurred in deeply anesthetized patients, no differences were found between the two volatile agents. When tracheal extubation of awake patients was performed, the use of isoflurane was associated with more episodes of coughing and airway obstruction than was halothane (P less than 0.05). Awake tracheal extubation following either agent was associated with significantly more episodes of hemoglobin desaturation than was tracheal extubation while anesthetized.

Anesthesia Recovery Period↗
PubMed1991

Anemia in pediatric day-surgery patients: prevalence and detection.

A prospective study was conducted to determine the prevalence of anemia in pediatric day-surgery patients, and a single-blinded study was conducted to evaluate the anesthesiologist's capability to detect preoperative anemia clinically. The subsequent management of children with anemia was noted. During the preoperative examination the anesthesiologist completed a questionnaire and predicted the preoperative hemoglobin concentration based on the history and physical examination. The preoperative hemoglobin concentration was measured for all of the patients, but the results were withheld until after completion of the questionnaire. Documentation was complete in 2,649 patients, and these comprised the final study group. Fourteen patients (0.5%) were anemic (hemoglobin concentration less than 100 g/l), but of these, only 5 had been predicted to be anemic based on clinical examination. Seven of these 14 anemic patients were less than 1 yr of age. Only 2 of the anemic patients had surgery postponed, and 1 of these also had a respiratory infection. Forty-four patients were incorrectly predicted to be anemic (i.e., their actual hemoglobin concentration was greater than 100 g/l). We conclude that in our patients, anemia is rare but is more likely to occur in those less than 1 yr of age. The presence of mild degrees of anemia does not alter the decision to proceed with day surgery. The anesthesiologists participating in this study could not reliably detect anemia clinically.

Adolescent↗
PubMed1990

Fentanyl dosage is associated with reduced blood glucose in pediatric patients after hypothermic cardiopulmonary bypass.

The authors retrospectively reviewed the charts of 36 pediatric patients who had undergone cardiac surgery with hypothermic cardiopulmonary bypass (CPB) (n = 24) or profound hypothermia with circulatory arrest (PHCA) (n = 12), none of whom had received dextrose in the clear CPB pump prime, maintenance iv fluids, or cardioplegia solution. The authors studied whether the doses of fentanyl or methylprednisolone, or rates of dextrose infusion from blood products during CPB or from vasoactive infusions in 5% dextrose in water, were correlated with the blood glucose concentrations at the termination of CPB. Because other investigations have indicated that even moderate hyperglycemia during cerebral hypoxia or ischemia may predispose patients to an increased risk of neurologic deficit, the authors wished to determine whether any of these factors might contribute significantly to the elevation in blood glucose commonly seen in these patients. Multiple regression analysis and ANOVA were performed on these data, and a P value of 0.0125 was considered significant. The dose of methylprednisolone, and rates of infusions of dextrose from blood products in the CPB pump prime or from 5% dextrose in water at the termination of CPB did not correlated significantly with the blood glucose level. The dose of fentanyl administered to patients prior to the end of CPB was significantly correlated with the glucose concentration (r2 = 0.416; P = 0.0001). No patient who received greater than or equal to 50 micrograms/kg of fentanyl had a blood glucose concentration of greater than 200 mg/dl.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1988

A comparative evaluation of intubating doses of atracurium, d-tubocurarine, pancuronium and vecuronium in children.

To determine the onset and recovery times and haemodynamic effects of intubating doses of atracurium (0.4 mg.kg-1), d-tubocurarine (0.8 mg.kg-1), pancuronium (0.12 mg.kg-1), and vecuronium (0.07 mg.kg-1), sixty-seven children aged one to eight years were studied under halothane and nitrous oxide anaesthesia. The time to maximum twitch depression and the time to recovery to T1/Tc 25 per cent were recorded with an integrated evoked EMG recorder. The heart rate and systolic blood pressure were recorded for five minutes after drug administration and prior to intubation. There was no difference in onset times between drugs. The recovery time to T1/Tc 25 per cent following vecuronium (25.5 +/- 6.3 min) was shorter than following atracurium (37.5 +/- 7.0 min). Recovery times for d-tubocurarine and pancuronium were greater than sixty minutes. Elevation of heart rate occurred after administration of pancuronium (+29.8 per cent to +38.6 per cent) and d-tubocurarine (+31 per cent to +34.9 per cent), but no change was observed after atracurium or vecuronium. Elevation of blood pressure was greatest following pancuronium (+10.8 to +14.8 per cent). No significant change was observed following atracurium or vecuronium. A transient lowering of blood pressure (-9.3 per cent) occurred following d-tubocurarine.

Atracurium↗
PubMed1988

A study of tape adhesive strength on endotracheal tubes.

A method of assessing the adhesive bond of tapes used to secure endotracheal (ET) tubes is described. Five kinds of tape and six different ET tubes including two silicone rubber, wire-reinforced tubes were tested. There are significant differences in the adhesive strength of different tapes, and in the adhesive bond formed by different ET tube materials. On the Portex clear ET tube, silk tape adhered best (p less than 0.001), followed by waterproof, cloth, dermiclear, and micropore tapes. Adhesive bonding by silk tape was significantly greater (p less than 0.001) for the three clear ET tubes (Portex clear, NCC clear, and Portex ivory) than for the Portex blue and the silicone rubber, wire-reinforced ET tubes. All tapes showed very poor or negligible adhesion to the Sheridan and Portex reinforced ET tubes. Adhesion to these tubes was greatly improved by wrapping them tightly with an "op site" dressing prior to applying tape.

Adhesives↗
PubMed1986

Failure of the tourniquet-twitch test as a diagnostic or screening test for malignant hyperthermia.

We have performed the tourniquet-twitch test of Roberts and Ryan in normal and in malignant hyperthermia (MH) patients and relatives. This test measures the ratio of electrically induced thumb twitches noted after 10 min of ischemia with those noted immediately prior to the ischemia. We found no significant differences in this ratio between normal subjects and those who have had MH reactions, or relatives of such individuals. Furthermore, we have observed no significant differences in tourniquet-twitch ratios between those with normal caffeine-halothane contractures and persons with caffeine-halothane contractures tests positive for MH. These findings do not agree with those of Roberts and Ryan, who reported that tourniquet-twitch ratios were higher in MH patients than in normal patients. We have, however, determined that subjects with tourniquet-twitch ratios greater than or equal to 1.8 are substantially younger than those with tourniquet-twitch ratios less than or equal to 1.0. Therefore we do not believe that the tourniquet-twitch test is useful as a diagnostic, or even as a screening test for MH.

Humans↗