Leila G. Welborn

Comparison of emergence and recovery characteristics of sevoflurane, desflurane, and halothane in pediatric ambulatory patients.

This study compares the emergence and recovery characteristics of sevoflurane, desflurane, and halothane in children undergoing adenoidectomy with bilateral myringotomy and the insertion of tubes.Eighty children 1-7 yr of age were studied. Thirty minutes prior to the induction of anesthesia, all patients received 0.5 mg/kg midazolam orally. Patients were randomly assigned to one of four groups: Group 1, sevoflurane induction and maintenance (S:S); Group 2, halothane induction and sevoflurane maintenance (H:S); Group 3, halothane induction and maintenance (H:H); or Group 4, halothane induction and desflurane maintenance (H:D). Tracheal intubation was facilitated with the use of a single dose of 0.2 mg/kg mivacurium. A Mapelson D circuit was used, and all patients received N2 O:O2 60:40 for induction and maintenance at standardized appropriate fresh gas flow. Ventilation was controlled to maintain normocapnia. End-tidal concentration of anesthetics was maintained at approximately 1.3 minimum alveolar anesthetic concentration (MAC) (halothane: 0.56; sevoflurane: 2.6; desflurane: 8.3) until the end of surgery when all anesthetics were discontinued. Emergence (extubation), recovery (Steward score 6), and discharge times were compared among patients in the four groups using analysis of variance and Newman-Keuls tests. P < 0.05 was considered significant. There were no significant differences among the four groups with respect to age, weight, duration of surgery, or duration of anesthesia. Emergence and recovery from anesthesia were significantly faster in the desflurane group (Group 4) compared with the sevoflurane and halothane groups (Groups 1, 2, and 3) (5 +/- 1.6 min vs 11 +/- 3.7, 11 +/- 4.0, 10 +/- 4.0 min and 11 +/- 3.9 min vs 17 +/- 5.5, 19 +/- 7.1, 21 +/- 8.5 min, respectively). There was a significantly greater incidence of postoperative agitation and excitement in patients who received desflurane (55%) versus sevoflurane (10%) and halothane (25%). There were no significant differences among the four groups with respect to the time to meet home discharge criteria (134 +/- 36.9, 129 +/- 53.3, 117 +/- 64.6, 137 +/- 22.6 in Groups 1, 2, 3, and 4, respectively), in the time to drink oral fluids (139 +/- 31.6, 136 +/- 53.8, 123 +/- 65.0, 142 +/- 29.4 min, respectively), or in the incidence of postoperative vomiting. It is concluded that, although desflurane resulted in the fastest early emergence from anesthesia, it was associated with a greater incidence of postoperative agitation. Sevoflurane resulted in similar emergence and recovery compared with halothane. Desflurane and sevoflurane did not result in faster discharge times than halothane in this patient population. (Anesth Analg 1996;83:917-20)

Postoperative apnea in former preterm infants: prospective comparison of spinal and general anesthesia.

Thirty-six former preterm infants undergoing inguinal hernia repair were studied. All were less than or equal to 51 weeks postconceptual age at the time of operation. Patients were randomly assigned to receive general or spinal anesthesia. Group 1 patients received general inhalational anesthesia with neuromuscular blockade. Group 2 patients received spinal anesthesia using 1% tetracaine 0.4-0.6 mg/kg in conjunction with an equal volume of 10% dextrose and 0.02 ml epinephrine 1:1000. In the first part of the study, infants randomized to receive spinal anesthesia also received sedation with im ketamine 1-2 mg/kg prior to placement of the spinal anesthetic (group 2 A). The remainder of group 2 patients did not receive sedation (group 2 B). Respiratory pattern and heart rate were monitored using an impedance pneumograph for at least 12 h postoperatively. Tracings were analyzed for evidence of apnea, periodic breathing and/or bradycardia by a pulmonologist unaware of the anesthetic technique utilized. None of the patients who received spinal anesthesia without ketamine sedation developed postoperative bradycardia, prolonged apnea, or periodic breathing. Eight of nine infants (89%) who received spinal anesthesia and adjunct intraoperative sedation with ketamine developed prolonged apnea with bradycardia. Two of the eight infants had no prior history of apnea. Five of the 16 patients (31%) who received general anesthesia developed prolonged apnea with bradycardia. Two of these five infants had no prior history of apnea. When infants with no prior history of apnea were analyzed separately, there was no statistically significant increased incidence of apnea in children receiving general versus spinal anesthesia with or without ketamine sedation. Because of the small numbers of patients studied, and the multiple factors that may influence the incidence of postoperative apnea (e.g., prior history of neonatal apnea), standard postoperative respiratory monitoring of these high-risk infants is still recommended following all anesthetic techniques.

Oxygen consumption and cardiovascular function in children during profound intraoperative normovolemic hemodilution.

The clinically acceptable limit of acute normovolemic, normothermic hemodilution, a standard procedure in scoliosis surgery, is not yet well defined.Eight ASA class I patients undergoing idiopathic scoliosis correction were administered a standard anesthetic with 100% oxygen and controlled ventilation. Hemodilution was accomplished by exchanging whole blood for 5% albumin in 0.9% saline. Blood gases, acid-base status, and circulatory variables were recorded prior to and after hemodilution, and every 30 min throughout surgery. The impact of hemodilution was judged by mixed venous oxygen saturation which was maintained at > or=to60%, while intravascular volume was maintained with the 5% albumin solution. Reinfusion of the autologous blood was completed by the end of surgery. In the eight controlled cases in which normovolemic hemodilution was studied, hemoglobin levels decreased from 10.0 +/- 1.6 g/dL to 3.0 +/- 0.8 g/dL. Mixed venous oxygen saturation decreased from 90.8% +/- 5.4% to 72.3% +/- 7.8%. Oxygen extraction ratio increased from 17.3% +/- 6.2% to 44.4% +/- 5.9%. Oxygen delivery decreased from 532.1 +/- 138.1 mL centered dot min-1 centered dot m-2 to 260.2 +/- 57.1 mL centered dot min-1 centered dot m-2, while global oxygen consumption did not decrease and plasma lactate did not appreciably increase. Central venous pressure increased and peripheral resistance decreased during hemodilution. Cardiac index increased, heart rate remained essentially constant, and left ventricular stroke work index did not decrease significantly. No patients suffered clinically adverse outcomes. Global oxygen transport and myocardial work can be maintained at extreme normovolemic anemia. Our evidence suggests that stages of normovolemic hemodilution more severe than previously reported may be clinically acceptable for young, healthy patients during normocarbic anesthesia. (Anesth Analg 1995;80:219-25)

Induction and maintenance characteristics of anesthesia with desflurane and nitrous oxide in infants and children.

To determine the induction and maintenance characteristics of desflurane in pediatric patients, the authors anesthetized 206 infants and children aged 1 month to 12 yr with nitrous oxide plus desflurane and/or halothane in oxygen. Patients were assigned to one of four groups: anesthesia was 1) induced and maintained with desflurane after premedication with an oral combination of meperidine, diazepam, and atropine; 2) induced and maintained with desflurane; 3) induced with halothane and maintained with desflurane; or 4) induced and maintained with halothane. An unblinded observer recorded time to loss of consciousness (lid reflex), time to intubation, and clinical characteristics of the induction and maintenance of anesthesia. Moderate-to-severe laryngospasm (49%) and moderate-to-severe coughing (58%) occurred frequently during induction of anesthesia with desflurane; the incidence of these was not altered by premedication. In contrast, laryngospasm and coughing were rare during induction of anesthesia with halothane. In unpremedicated patients, time to loss of lid reflex (mean +/- SD) was similar for desflurane (2.4 +/- 1.2 min) and halothane (2.1 +/- 0.8 min). During induction of anesthesia, before laryngoscopy and intubation, mean arterial pressure less than 80% of baseline was more common with halothane; heart rate and mean arterial pressure greater than 120% of baseline were more common with desflurane. Intraoperatively, heart rate greater than 120% of baseline was more common with desflurane; blood pressures were similar for the two anesthetics. The authors conclude that the high incidence of airway complications during induction of anesthesia with desflurane limits its utility for inhalation induction in pediatric patients. Anesthesia can be safely maintained with desflurane if induced with a different anesthetic.

Anemia and postoperative apnea in former preterm infants.

To examine the association between anemia and postoperative apnea in former preterm infants, 24 former preterm infants of less than 60 weeks postconceptual age undergoing inguinal hernia repair were studied. A hematocrit of at least 25% was required for study participation. General endotracheal inhalational anesthesia, supplemented with neuromuscular blockade and controlled ventilation, was used. No barbiturates or opioids were administered. Respiratory pattern and heart rate were recorded for at least 12 h postoperatively using an impedance pneumograph. Tracings were analyzed for evidence of apnea, periodic breathing, and/or bradycardia by a pulmonologist unaware of the hematologic profile of the infant. Nineteen patients had a hematocrit of 30% or greater (group 1). Their mean (+/- standard deviation [SD]) gestational age was 33.5 +/- 2.7 weeks and postconceptual age 45.5 +/- 4.6 weeks. Five infants had a hematocrit less than 30% (group 2). Their mean gestational age (+/- SD) was 32.4 +/- 3.2 weeks and postconceptual age 43.6 +/- 5.5 weeks. Anemic infants had an 80% incidence of postoperative apnea versus 21% in infants with a normal hematocrit (P less than .03). In the infants who developed postoperative prolonged apnea and/or bradycardia, a prior history of apnea was equally present in both groups (21% in group 1 and 20% in group 2). This study shows that anemia in former preterm infants can be associated with an increased incidence of postoperative apnea.

High-dose caffeine suppresses postoperative apnea in former preterm infants.

Thirty-two former preterm infants (less than or equal to 44 weeks postconceptual age) undergoing inguinal hernia repair were prospectively studied. General inhalational anesthesia with neuromuscular blockade was used. No barbiturates or opioids were given. Infants were randomly divided into two groups. Group 1 received iv caffeine 10 mg/kg immediately after induction of anesthesia. Group 2 received iv saline. Respiratory pattern, heart rate, and SpO2 were monitored using an impedance pneumograph and a pulse oximeter, respectively, for at least 12 h postoperatively. Tracings were analyzed for evidence of apnea, periodic breathing, and/or bradycardia by a pulmonologist unaware of the drug given. None of the patients who received caffeine developed postoperative bradycardia, prolonged apnea, or periodic breathing, and none had postoperative SpO2 less than 90%. In the control group 13 (81%) developed prolonged apnea 4-6 h postoperatively. Fifty percent of the patients had SpO2 less than 90% at the time. This study shows that iv caffeine 10 mg/kg is effective in the control of apnea in otherwise healthy expremature infants between 37 and 44 weeks of postconceptual age. It is still recommended, however, that all infants at risk be monitored for at least 12 h for apnea and bradycardia following general anesthesia.

Anesthesia and Apnea: Perioperative Considerations in the Former Preterm Infant

Former preterm infants younger than 44 weeks postconceptual age are at increased risk for developing postoperative apnea and PB. When surgery cannot be deferred until the infant is developmentally more mature, several measures should be taken to minimize the risk of ventilatory dysfunction. First, outpatient surgery is not advisable for infants younger than 44 weeks postconceptual age. All infants should be admitted to the hospital and monitored for apnea and bradycardia for at least 12 to 18 hours after surgery. Second, we recommend the use of intravenous caffeine base 10 mg/kg in all infants at risk for postoperative apnea following general anesthesia. Preliminary studies of a small number of patients indicate that spinal anesthesia without sedation is associated with less apnea than is general anesthesia or spinal anesthesia with ketamine sedation. This option warrants further consideration. Infants with anemia of prematurity, generally a benign condition, are at increased risk for postoperative apnea. It is therefore preferable to delay elective surgery and supplement the feeds with iron until the Hct is above 30%. When surgery cannot be deferred, anemic infants must be observed and monitored carefully in the postoperative period.

Comparison of propofol and thiopental for rapid anesthesia induction in infants.

We compared the hemodynamic response to laryngoscopy and intubation, as well as emergence and recovery times, when propofol or thiopental were used for rapid intravenous induction of anesthesia in 59 infants undergoing repair of inguinal hernia. An intravenous catheter was inserted under N2O analgesia and atropine 0.01 mg/kg was administered to all patients. Subsequent induction with propofol (3 mg/kg), thiopental (5 mg/kg), or halothane (2%) was followed with succinylcholine (2 mg/kg) and tracheal intubation. Ventilation was manually assisted during surgery, and tracheas were extubated when patients were completely awake. Infants who received propofol showed less hypertensive response to intubation than those who received thiopental or halothane. In the 1- to 6-mo age group, emergence (extubation) time was significantly longer for infants who received thiopental (10.2 +/- 1.4 min) than for those who received propofol or halothane (5.5 +/- 2.5 and 6.2 +/- 1.3 min, respectively). Infants who received thiopental induction had a higher incidence of perioperative airway complications than all others. There was no significant difference in the recovery and discharge times among the three groups. We conclude that when rapid intravenous induction is required for infants, propofol is more effective than thiopental in obtunding the hypertensive response to intubation, and in young infants (1-6 mo) it results in more prompt emergence after short surgical procedures.

Safety and Outcomes of Outpatient Pediatric Otolaryngology Procedures at an Ambulatory Surgery Center

Objectives: To determine the safety and outcomes of outpatient pediatric otolaryngology procedures performed at an ambulatory surgery center (ASC).

Induction and recovery characteristics of desflurane and halothane anaesthesia in paediatric outpatients

This study compares induction and recovery characteristics of desflurane and halothane in children undergoing elective outpatient surgery (hernia repair, circumcision and orchidopexy). Fifty‐six patients one month to 12 years of age were randomly assigned to one of three study groups. In addition to nitrous oxide, group I received desflurane (D) for induction and maintenance; group II received halothane (H) for induction and desflurane for maintenance; and group III received halothane for induction and maintenance. All patients received caudal blocks at the end of surgery. There was no significant difference in induction time (mean ± SD) among the three groups (1.7 ± 0.5, 1.7 ± 0.5 and 1.0 ± 0.5 min for groups I, II and III respectively). Airway complications (coughing, breath holding, and laryngospasm) were significantly higher among the children induced with desflurane than among either of the halothane induction groups. Premedication had no effect on reducing the number of airway complications. Emergence and recovery times (mean ± SD) were significantly shorter among both desflurane maintenance groups (3.6 ± 1.7 and 11 ± 8 min) than among the group maintained on halothane (7.9 ± 3.5 and 29.9 ± 10.6 min respectively). A brief halothane induction did not compromise the fast recovery characteristics of desflurane. There was no difference among the groups in time to discharge home (approx. 3 h). This study confirms the value of desflurane as a maintenance agent in paediatric anaesthesia. In our patients, a brief halothane induction did not compromise the fast recovery characteristics of desflurane.