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Biomedical subjects

M F Watcha

Publications and source records attributed to M F Watcha.

48 records · Page 3Linked to original sources
PubMed1991

Effect of propofol on the incidence of postoperative vomiting after strabismus surgery in pediatric outpatients.

Vomiting is a common problem after strabismus surgery in pediatric outpatients. We compared the effects of propofol with and without N2O and droperidol to the effects of a conventional regimen consisting of halothane-N2O-droperidol on the recovery characteristics and the incidence of postoperative emesis after strabismus surgery in 120 ASA physical status 1 or 2 children. After induction of anesthesia with halothane-N2O, patients were randomly assigned to one of four groups. Group A (control) received halothane, 66% N2O, and droperidol 75 micrograms.kg-1; group B, propofol 2 mg.kg-1 bolus followed by infusion of 160 microgram.kg-1.min-1; group C, propofol (as in group B) and 66% N2O; and group D, propofol (as in group B), 66% N2O (as in group C), and droperidol 75 micrograms.kg-1. Patients in group B had more episodes of intraoperative oculocardiac reflex responses than patients in group A, but had shorter times to extubation, oral intake, ambulation, and discharge, as well as a lower incidence of postoperative emesis (P less than 0.05). The addition of N2O to the propofol anesthetic regimen (group C) was associated with an increased incidence of emesis (P less than 0.05), whereas the addition of droperidol to the propofol-N2O regimen (group D) did not affect the incidence of emesis compared to the other three groups. We conclude that maintenance of anesthesia with a total intravenous regimen using propofol results in a more rapid recovery and less postoperative emesis than with a halothane-N2O-droperidol regimen.(ABSTRACT TRUNCATED AT 250 WORDS)

Ambulatory Surgical Procedures↗
PubMed1991

Effect of intraoperative analgesic therapy on end-expired concentrations of halothane associated with spontaneous eye opening in children.

We studied 94 healthy ASA physical status I or II children to determine the end-expired concentration of halothane associated with eye opening on emergence from anesthesia, and to determine if parenteral opioid therapy or regional analgesia significantly altered this concentration. In our study, anesthesia was maintained with halothane in an air-oxygen mixture. After the surgical procedure was completed, the inspired concentration of halothane was adjusted to zero and the end-expired concentrations were permitted to decrease spontaneously. The end-expired concentration at which the child spontaneously opened his or her eyes was recorded. There were no statistically significant differences in the values of the end-expired halothane concentration at eye opening between patients in the control group, who did not receive any supplementation of halothane anesthesia, and patients in the groups that received either morphine supplementation or regional analgesia. These data suggest that analgesia and hypnosis (or loss of consciousness) occur by different mechanisms during halothane anesthesia in children.

Adolescent↗
PubMed1990

Effects of halothane on intraocular pressure in anesthetized children.

Intraocular pressure (IOP) measurements in children are usually performed under nitrous oxide and halothane anesthesia. We studied the effects of both time and end-tidal halothane concentration on IOP in 80 children (mean age +/- SD = 4.5 +/- 2.9 yr), to determine the most optimal time to make such measurements in anesthetized children. In 30 children the end-tidal halothane and nitrous oxide concentrations were kept constant while IOP was measured at 1-min intervals after the induction of anesthesia. Intraocular pressure did not change with time. In another 50 children IOP was measured immediately after induction, after 10 min of steady-state end-tidal halothane concentrations of both 0.5% and 1.0% in 66% nitrous oxide, and immediately after tracheal intubation. Intraocular pressure did not differ significantly at either halothane concentration but increased after tracheal intubation. We conclude that in patients anesthetized with halothane and nitrous oxide, IOP after induction remains constant over time and is not affected by end-tidal halothane concentrations up to 1.0% but is affected by tracheal intubation. Thus, the optimal time to measure IOP in children receiving up to 1% halothane in 66% nitrous oxide is during the first 10 min after induction, but before tracheal intubation.

Anesthesia, Inhalation↗
PubMed1989

Pulse oximetry in methemoglobinemia.

Pulse oximetry is a major improvement in the assessment of oxygenation. The device uses plethysmography and light absorbance measurements at two wavelengths to estimate oxygen saturation. It is inaccurate, however, when more than two types of hemoglobin are present. This article describes two infants with methemoglobinemia in whom pulse oximetry overestimated oxygen saturation. We discuss the mechanism of this systematic error and emphasize that pulse oximetry should not be used to estimate true oxygen saturation in the presence of methemoglobin. However, a disparity between oxygen saturation estimates by pulse oximetry and by calculations based on the arterial partial pressure of oxygen and the oxygen-hemoglobin dissociation curve can provide an important clue to the presence of such abnormal types of hemoglobins. Therapy should be based on direct measurements of oxyhemoglobin by cooximetry and not on measurements of oxygen saturation by pulse oximetry or on saturations calculated from the Pao2 and the oxyhemoglobin dissociation curve.

Carboxyhemoglobin↗
PubMed1989

Failure of lower esophageal contractility to predict patient movement in children anesthetized with halothane and nitrous oxide.

The clinical usefulness of monitoring the frequency of spontaneous lower esophageal contractions (SLEC) to assess the depth of anesthesia was evaluated in 38 children. The hypothesis that SLEC can predict movement in response to skin incision during nitrous oxide and halothane anesthesia was tested. Although movement in response to skin incision was correlated with an increase in heart rate, blood pressure, and an increased SLEC frequency, there was no correlation between the SLEC prior to skin incision and movement in response to this stimulus. Moreover, cardiovascular responses preceded the detection of SLEC changes. The relationship between changes in SLEC activity and times to awakening during emergence from anesthesia was also examined. During emergence from anesthesia there was an increase in SLEC, but the time to awakening could not be predicted from the SLEC. Cardiovascular changes again preceded SLEC changes during emergence. Monitoring of the lower esophageal contractility rate would appear to be of limited usefulness in evaluating the depth of anesthesia in unparalyzed children during nitrous oxide and halothane anesthesia.

Adolescent↗
PubMedDate not supplied

Intraocular pressure and hemodynamic changes following tracheal intubation in children.

STUDY OBJECTIVE: To determine the optimal time in which to make intraocular pressure (IOP) measurements in children following tracheal intubation. DESIGN: Randomized, controlled trial. SETTING: Operating rooms of a tertiary-care children's hospital. PATIENTS: Thirteen healthy children undergoing elective strabismus correction surgery under halothane and nitrous oxide (N2O) endotracheal anesthesia. INTERVENTIONS: Following induction of anesthesia, patients were randomly assigned to receive stable end-tidal halothane concentrations of 0.5% or 1.0% in 66% N2O. MEASUREMENTS AND MAIN RESULTS: Baseline (preintubation) IOP, heart rate (HR), and mean arterial pressure (MAP) were recorded after 10 minutes of steady-state end-tidal concentrations. These measurements were repeated at 1-minute intervals following tracheal intubation, which was facilitated with atracurium. HR and MAP changes were found to be good predictors of IOP changes. IOP returned to baseline (preintubation) values when HR and MAP returned to preintubation levels. However, IOP measurements under anesthesia may not reflect awake values. CONCLUSIONS: We recommend that IOP be measured only after HR and MAP have returned to preintubation levels in children who have undergone tracheal intubation during halothane and N2O anesthesia.

Anesthesia, Endotracheal↗
PubMedDate not supplied

Mivacurium as an alternative to succinylcholine during outpatient laparoscopy.

STUDY OBJECTIVES: To compare (1) the adequacy of conditions for tracheal intubation; (2) the onset, depth, clinically effective duration, and recovery profile; and (3) adverse effects associated with mivacurium as an alternative to succinylcholine during general (endotracheal) anesthesia for outpatient laparoscopy. DESIGN: A randomized, controlled clinical trial. SETTING: Barnes Hospital Outpatient Surgery Center. PATIENTS: Sixty healthy consenting ASA physical status I or II adult female outpatients. INTERVENTIONS: Following a standardized thiopental sodium-alfentanil induction, patients were randomly assigned to one of three groups: Group I-alfentanil-nitrous oxide (N2O)-succinylcholine; Group II-alfentanil-N2O-mivacurium; Group III-enflurane-N2O-mivacurium. MEASUREMENTS AND MAIN RESULTS: Neuromuscular blockade was measured by electromyography of the stimulated adductor pollicis muscle contraction. Tracheal intubation was attempted after achieving 70% or greater blockade and was graded on a four-point scale. Onset and recovery were more rapid with succinylcholine than with mivacurium. The clinically effective duration of action of mivacurium was not significantly different in the enflurane-N2O group compared with the alfentanil-N2O group. Side effects with mivacurium included flushing and occasional wheezing. CONCLUSIONS: Mivacurium 0.15 mg/kg given intravenously provided good to excellent conditions for tracheal intubation in 2 to 3 minutes. This dose provided a clinically effective duration of action of 20 to 25 minutes, and the residual blockade was readily reversible with neostigmine. Mivacurium did not, however, offer any apparent advantage over succinylcholine in this outpatient population.

Adult↗
PubMedDate not supplied

Cost-effectiveness analysis of antiemetic therapy for ambulatory surgery.

STUDY OBJECTIVE: To compare the relative cost-effectiveness ratios of (1) therapy with ondansetron, droperidol, and metoclopramide in the prevention of postoperative nausea and vomiting (PONV), and (2) prophylactic versus rescue therapy of PONV with these agents. DESIGN: Cost-effectiveness analysis based on the estimated costs of 12 mutually exclusive outcomes identified by decision analysis. SETTING: Computer model of outcome established using data extracted from published studies and a survey of current practice in two university-affiliated hospitals. PATIENTS: Patients undergoing operations associated with a high risk of PONV. INTERVENTIONS: The cost-effectiveness of prophylactic antiemetic therapy was compared among three drugs and also compared with limiting treatment to established PONV. MEASUREMENTS AND MAIN RESULTS: Direct costs included drug acquisition, drug delivery, equipment used in managing vomiting, and additional nursing time costs. Indirect costs included drugs and materials used to treat persistent nausea and/or vomiting and the side effects of prophylactic drugs, increased time spent in the postanesthesia care unit, unanticipated hospitalization, and lost earnings due to hospitalization. Separate models were created for patients with both nausea and vomiting and with isolated nausea. The total incremental costs associated with the prophylactic use of ondansetron, metoclopramide, and droperidol were $37.74, $28.43, and $18.17 per patient, respectively. The costs per emesis-free patient with the prophylactic use of ondansetron, metoclopramide, and droperidol, were $55.91, $71.08, and $30.15, respectively, and per nausea-free patient $68.93, $82.74, and $33.52, respectively. Prophylactic antiemetic therapy was cost-effective for operations with a high frequency of emesis, whereas treatment of established symptoms was more cost-effective when the frequency was lower. For ondansetron, prophylactic use was cost-effective only when the frequency of emesis exceeded 33%, whereas prophylactic droperidol was cost-effective even if the frequency was 10%. CONCLUSIONS: When drug costs, efficacy, and adverse events were all considered, prophylactic droperidol was more cost-effective than ondansetron, and both drugs were more cost-effective than metoclopramide. However, the expected frequency of PONV, as well as local drug acquisition costs, can significantly influence whether a particular antiemetic is cost-effective when given prophylactically or only as therapy for established PONV.

Ambulatory Surgical Procedures↗