The clinical and biochemical effects of propofol infusion with and without EDTA for maintenance anesthesia in healthy children undergoing ambulatory surgery

We conducted this randomized, double-blinded, comparative, parallel-group study to determine whether adding EDTA to propofol would affect the clinical profile, calcium and magnesium homeostasis, or renal function in healthy children. After the induction of anesthesia with halothane, 69 ambulatory surgical patients (1 mo to <17 yr old), received propofol without EDTA (n = 33) or propofol with EDTA (n = 36). Blood samples were obtained for the measurement of ionized calcium, ionized magnesium, and laboratory indicators of renal function. Hemodynamic measurements, recovery, and adverse events were recorded. Propofol with EDTA produced no significant effects on clinical efficacy or renal function. Propofol and propofol EDTA produced a statistically significant decrease from baseline in serum concentrations of ionized calcium and magnesium during infusion (P<0.05), but with no apparent clinical effect. Hemodynamic measurements generally remained stable and were similar for both groups. Statistically significant changes in systolic blood pressure, mean arterial pressure, and heart rate were not considered clinically significant. Adverse events were mild or moderate. The addition of EDTA does not alter the clinical profile of propofol in pediatric ambulatory surgical patients. With or without EDTA, propofol is associated with a decrease in ionized calcium with no apparent clinical effect.

IMPLICATIONS

The addition of EDTA does not alter the clinical profile of propofol in pediatric ambulatory surgical patients. With or without EDTA, propofol is associated with a decrease in ionized calcium with no apparent clinical effect.

The incidence of emergence agitation associated with desflurane anesthesia in children is reduced by fentanyl

The rapid emergence and recovery from general anesthesia provided by desflurane is associated with a frequent incidence of emergence agitation in children. We sought to determine the mean effective dose of fentanyl that would significantly reduce the incidence of emergence agitation while preserving rapid recovery. Thirty-two children undergoing adenoidectomy received general anesthesia with desflurane and a dose of fentanyl (1.25, 1.87, 2.8, and 4.2 microg/kg) determined by the classic up-down method. Recovery characteristics, including time to extubation, recovery, hospital discharge, agitation, pain, and vomiting, were recorded. Demographics and recovery features were assessed by analysis of variance and Kruskal-Wallis tests. The mean effective dose of fentanyl to reduce agitation was calculated with the Dixon-Massey method to be 2.5 +/- 6.2 microg. There were no significant differences when treatment groups were compared for recovery criteria. Postoperative emesis occurred in 75% of patients. The results of this study demonstrate that a dose of 2.5 microg/kg of fentanyl is sufficient to prevent emergence agitation while preserving the rapid recovery associated with desflurane anesthesia in children undergoing adenoidectomy.

IMPLICATIONS

A dose of 2.5 microg/kg of fentanyl prevents emergence agitation associated with desflurane anesthesia in children undergoing adenoidectomy without delaying emergence.

Pediatric otolaryngologic emergencies

Anesthesiologists are often consulted to help in the management of pediatric otolaryngologic emergencies. These include airway obstruction in children suffering from acute epiglottitis and croup. Surgical otolaryngologic emergencies such as foreign body aspiration, post-tonsillectomy bleeding, obstructive laryngeal papillomatosis, peritonsillar abscess, and laryngeal trauma can be life threatening. The pathophysiology, clinical course, and anesthetic management of these conditions are addressed with special emphasis on the details of airway management in each case.

The effect of intranasal fentanyl on the emergence characteristics after sevoflurane anesthesia in children undergoing surgery for bilateral myringotomy tube placement

Children undergoing placement of bilateral myringotomy tubes (BMT) often exhibit pain-related behavior (agitation) in the postanesthesia care unit. We compared the emergence and recovery profiles of pediatric patients who received sevoflurane with or without supplementary intranasal fentanyl for BMT surgery. By using a prospective, double-blinded design, 150 children 6 mo to 5 yr of age, scheduled for routine BMT surgery, were anesthetized with sevoflurane (2%-3%) in a 60% N(2)O/O(2) gas mixture. Patients were randomized to receive equal volumes of intranasal saline (Control), 1 microg/kg fentanyl or 2 microg/kg fentanyl. A blinded observer evaluated each patient using a previously described 4-point agitation scale and the Steward recovery scale. Response to parental presence was observed after a score of six (full recovery) was achieved on the Steward recovery scale. There were no significant differences among the three groups regarding age, weight, surgeon, duration of anesthesia, or ear condition. Recovery times and emergence characteristic scores were not statistically different. Agitation scores were significantly reduced in the 2-microg/kg Fentanyl group as compared with the Control group (P = 0.012). Fentanyl 2 microg/kg is recommended to reduce the incidence of agitation seen in these patients.

IMPLICATIONS

We examined the use of nasally administered fentanyl for the relief of agitation or discomfort after placement of bilateral myringotomy tubes in 150 children ages 6 mo to 5 yr using a prospective, double-blinded design. Fentanyl 2 microg/kg was found to reduce the incidence of agitation in these patients.

Fast-tracking children after ambulatory surgery

This study was designed to determine the feasibility and benefits of fast-tracking children after ambulatory surgery. One-hundred-fifty-five healthy children undergoing surgical procedures lasting <90 min were studied in a randomized manner. After surgery, children who met predefined recovery criteria in the operating room were entered into one of the study groups. Seventy-one patients (control) were first admitted to the postanesthesia care unit (PACU) and then to the second-stage recovery unit (SSRU). Eighty-four children bypassed the PACU and were directly admitted to the SSRU (Fast-Track group). The demographic data, airway management, and surgical procedures were similar in both groups of patients. During the recovery phase, 62.0% of the PACU group patients and 40.5% of the Fast-Track patients received analgesics (P = 0.01). The total recovery time was 79.1 +/- 48.3 min in the Fast-Track group and 99.4 +/- 48.6 min in the Control group (P = 0.008). A larger percentage of parents in the Fast-Track group (31% vs 16%) reported that their child was restless on arrival at the SSRU (P = 0.037). There were no clinically significant adverse events. However, adequate pain control must be provided before transfer to SSRU. In conclusion, fast-tracking children after ambulatory surgery is feasible and beneficial when specific selection criteria are used.

IMPLICATIONS

The results of this study show that the total recovery time is shorter in children who are fast-tracked (bypass the postanesthesia care unit) after ambulatory surgery. A higher percentage of parents of the Fast-Track group felt that their child was restless on arrival at the second-stage recovery unit. Fast-tracking children after ambulatory surgery is feasible and beneficial when specific selection criteria are used.

Intramuscular rapacuronium in infants and children: a comparative multicenter study to confirm the efficacy and safety of the age-related tracheal intubating doses of intramuscular rapacuronium (ORG 9487) in two groups of pediatric subjects

BACKGROUND

This multicenter, assessor, blinded, randomized study was conducted to confirm and extend a pilot study in which intramuscular rapacuronium was given to infants and children to confirm efficacy and to evaluate tracheal intubating conditions.

METHODS

Ninety-six pediatric patients were studied in two groups: infants aged 1 to 12 months (n = 46) and children aged 1 to 3 yr (n = 50). Infants received 2.8 mg/kg and children 4.8 mg/kg of intramuscular rapacuronium during 1 minimum alveolar concentration halothane anesthesia. These two groups were studied in three subgroups, depending on the time (1.5, 3, or 4 min) at which tracheal intubation was attempted after the administration of intramuscular rapacuronium into the deltoid muscle. Neuromuscular data collected included onset time, duration of action, and recovery data during train-of-four stimulation at 0.1 Hz. Data were analyzed by the Cochran-Mantel-Haenszel procedure.

RESULTS

The tracheal intubating conditions were deemed acceptable in 17, 36, and 64% of infants and 20, 47, and 71% of children at 1.5, 3, or 4 min, respectively. The mean values for % of control twitch height (T1) 2 min after rapacuronium in both groups were similar. The mean (SD) time required to achieve more than or equal to 95% twitch depression in infants was 6.0 (3.7) versus 5.5 (3.8) min in children.

CONCLUSIONS

Only 27% of patients achieved clinically acceptable tracheal intubating conditions at 1.5 or 3 min after administration of 2.8 mg/kg and 4.8 mg/kg rapacuronium during 1 minimum alveolar concentration halothane anesthesia. Tracheal intubation conditions at 4 min were acceptable in 69% of subjects. The duration of action of 4.8 mg/kg of rapacuronium in children was longer than 2.8 mg/kg of rapacuronium in infants.

Laboratory tests in children undergoing ambulatory surgery: a review of clinical practice and scientific studies

The drive for cost containment in the United States has lead anesthesiologists to re-assess the benefits of routine pre-operative laboratory and radiological testing. The value of routine tests has been questioned not only by insurance companies but also by physicians. Common pre-operative laboratory and radiological tests are reviewed in the following analysis. Specifically, the use of such tests in children scheduled for ambulatory surgery is discussed. Current clinical practice patterns of pediatric anesthesiologists are included so that physicians may make conclusions on the basis of published literature and clinical practice of peers.

A randomized, double-blinded study of remifentanil versus fentanyl for tonsillectomy and adenoidectomy surgery in pediatric ambulatory surgical patients

We compared, in a double-blinded manner, the anesthetic maintenance and recovery properties of remifentanil with a clinically comparable fentanyl-based anesthetic technique in pediatric ambulatory surgical patients. Anesthesia was induced with either halothane or sevoflurane and nitrous oxide and oxygen. Patients were randomized (computer generated) to receive either remifentanil or fentanyl in a blinded syringe with nitrous oxide and oxygen in one of four possibilities: halothane/remifentanil, halothane/fentanyl, sevoflurane/remifentanil or sevoflurane/fentanyl. In patients receiving remifentanil, a placebo bolus was administered, and a continuous infusion (0.25 microg. kg(-1). min(-1)) was begun. In patients receiving fentanyl, a bolus (2 microg/kg) was administered followed by a placebo continuous infusion. The time from discontinuation of the anesthetic to extubation, discharge from the postanesthesia care unit (PACU), and discharge to home, as well as pain scores, were assessed by a blinded nurse observer. Systolic blood pressure and heart rate were noted at selected times, and adverse events were recorded. Remifentanil provided faster extubation times and higher pain-discomfort scores. PACU and hospital discharge times were similar. There were no statistical differences among the groups for adverse events. There were statistically, but not clinically, significant differences in hemodynamic variables. We noted that continuous infusions of remifentanil were intraoperatively as effective as bolus fentanyl. Although patients could be tracheally extubated earlier with remifentanil, this did not translate to earlier PACU or hospital discharge times. In addition, remifentanil was associated with higher postoperative pain scores. The frequent incidence of postoperative pain observed in the postoperative recovery room suggests that better intraoperative prophylactic analgesic regimens for postoperative pain control are necessary to optimize remifentanil's use as an anesthetic for children.

IMPLICATIONS

This is a study designed to examine the efficacy and safety of a short-acting opioid, remifentanil, when used in pediatric patients. The frequent incidence of postoperative pain observed in the postoperative recovery room suggests that better intraoperative prophylactic analgesic regimens for postoperative pain control are necessary to optimize remifentanil's use as an anesthetic for children.

The potency (ED50) and cardiovascular effects of rapacuronium (Org 9487) during narcotic-nitrous oxide-propofol anesthesia in neonates, infants, and children

We studied the neuromuscular blocking effects of rapacuronium (Org 9487) (dose-response curve, onset, and 50% effective dose [ED50] value), and changes in heart rate and blood pressure, as well as evidence of histamine release in neonates, infants, and children in an open-label, randomized, two-center study. Fifteen neonates, 30 infants, and 30 children were studied. Anesthesia was induced and maintained with propofol, nitrous oxide:oxygen (60:40), and fentanyl. Mechanomyographic monitoring of neuromuscular function was performed at the thumb. The potency (ED50) for neonates, infants, and children were 0.32 (95% confidence interval [CI] 0.15-0.61), 0.28 (95% CI 0.11-0.61), and 0.39 (95% CI 0.17-0.85) mg/kg, respectively. Neonates who received 0.3, 0.6, or 0.9 mg/kg Org 9487 developed a maximum T1 twitch depression of 34 +/-28%, 98 +/- 3%, and 99 +/- 2%, respectively. Time-to-peak effect (onset time) for 0.9 mg/kg Org 9487 was 57 +/- 20 s. Maximum percent T1 twitch depression (+/-SD) in infants who received 0.3, 0.6, or 0.9 mg/kg rapacuronium was 41 +/- 34%, 96 +/- 7%, and 100 +/- 1%, respectively. Time-to-peak effect for 0.9 mg/kg Org 9487 was 62 +/- 29 s. In children 0.3, 0.6, and 0.9 mg/kg rapacuronium resulted in an average percent T1 twitch suppression of 29 +/- 23, 83 +/- 11, and 90 +/- 16, respectively. Time-to-peak effect of 0.9 mg/kg Org 9487 was 96 +/- 33 s, respectively. There was no evidence of histamine release or significant changes in heart rate or blood pressure in either group at any dose. Rapacuronium is a low-potency nondepolarizing muscle relaxant with a fast onset of relaxation and minimal cardiovascular effects. Its potency (ED50) is similar in neonates (0.32 mg/kg), infants (0.28 mg/kg), and children (0.39 mg/kg). T1 suppression (90% +/- 16) is less and time to peak effect (96 +/- 33 s) is greater (0.9 mg/kg rapacuronium) in children, compared with the combined group of infants and neonates.

IMPLICATIONS

This study assesses the potency of rapacuronium (Org 9487) in pediatric patients. The potency of rapacuronium is similar in neonates (0.32 mg/kg), infants (0.28 mg/kg), and children (0.39 mg/kg).

Preoperative laboratory testing in children undergoing elective surgery: analysis of current practice

STUDY OBJECTIVE

To evaluate current practice in preoperative testing of healthy children undergoing elective surgery that is not expected to result in significant blood loss.

DESIGN

Survey of members of the Society for Pediatric Anesthesia.

SETTING

Anesthesiologists practicing in North America.

POPULATION

A total of 1,200 questionnaires were mailed.

INTERVENTIONS

Questionnaires were mailed to all members of the Society for Pediatric Anesthesia. All members were asked to specify which tests were routinely performed and to state why. Specific questions were asked about performing complete blood count (CBC), hemoglobin (Hb), hematocrit (Hct), and urine analysis (UA) in all patients, pregnancy test in adolescents, prothrombin time (PT) and activated partial thrombin time (PTT) prior to tonsillectomy, and sickle cell testing in black and/or Mediterranean children.

MEASUREMENTS AND MAIN RESULTS

685 of 1,200 (57%) questionnaires were returned. No attempt was made to identify and follow-up with nonresponders. Hb testing is routinely performed in 27% to 48% of the children depending on the age of the patient. UA is ordered preoperatively in less than 15% of the children. Pregnancy test was ordered by 43% of the respondents. Hemostatic tests prior to tonsillectomy were conducted by 45% of the anesthesiologists.

CONCLUSION

The results indicate the present practice of routine preoperative laboratory testing for children undergoing elective outpatient surgery. In spite of the many studies that indicate no specific benefits of performing routine preoperative testing in healthy children undergoing scheduled surgery, many physicians continue to order these tests in all such children.

Evaluation of awakening and recovery characteristics following anaesthesia with nitrous oxide and halothane fentanyl or both for brief outpatient procedures in infants

This study compared recovery characteristics and postoperative ventilatory function when halothane, fentanyl or combination of halothane and fentanyl in addition to N2O were used for intraoperative anaesthesia in term infants undergoing hernia repair as outpatients. Sixty-six full term ASA PS I infants ages 1-12 months were studied. All received inhalation induction with N2O, O2 and halothane, followed by intravenous atropine and atracurium, tracheal intubation, and controlled ventilation. For anaesthesia maintenance, patients were randomized into one of three groups. Group I received 70% N2O, 30% O2 and halothane. Group II received 70% N2O, 30% O2, halothane and 2 micrograms.kg-1 fentanyl. Group III received 70% N2O, 30% O2 and 10 micrograms.kg-1 fentanyl. Awakening times were similar in all three groups, however, Group I patients had significantly shorter recovery and discharge times than those of Group II and III. None of the patients experienced postoperative apnoea or periodic breathing. One patient in Group III experienced two brief episodes of bradycardia not associated with apnoea or arterial desaturation (SpO2 > 90% for greater than 30 s). Decreased SpO2 occurred less frequently in Group I (5.9%) compared to Group II (22.7%) and Group III (19.0%) patients, however, the group differences were not significant. Transcutaneous CO2 (TcCO2) values were not statistically different among the three groups. Pain scores were initially lower in Groups II and III, but at 120 min the differences were not significant. Postoperative apnoea was not observed in this study. SpO2 < 90% and TcCO2 > 9 kPa (70 mmHg) was more common in infants receiving 2 and 10 micrograms.kg-1 fentanyl than in infants receiving halothane and nitrous oxide anaesthesia. Infants < 3 months old did not have a higher incidence of SpO2 < 90% or significantly higher TcCO2 values when compared to infants > 3 months old. Fentanyl in doses used in this study did not prolong awakening time but did prolong recovery and discharge times in outpatient infants.

Single-dose ondansetron prevents postoperative vomiting in pediatric outpatients

This randomized, double-blind, parallel-group, multicenter study evaluated the safety and efficacy of ondansetron (0.1 mg/kg to 4 mg intravenously) compared with placebo in the prevention of postoperative vomiting in 429 ASA status I-III children 1-12 yr old undergoing outpatient surgery under nitrous oxide- and halothane-based general anesthesia. The results show that during both the 2-h and the 24-h evaluation periods after discontinuation of nitrous oxide, a significantly greater percentage of ondansetron-treated patients (2 h 89%, 24 h 68%) compared with placebo-treated patients (2 h 71%, 24 h 40%) experienced complete response (i.e., no emetic episodes, not rescued, and not withdrawn; P < 0.001 at both time points). Ondansetron-treated patients reached criteria for home readiness one-half hour sooner than placebo-treated patients (P < 0.05). The age of the child, use of intraoperative opioids, type of surgery, and requirement to tolerate fluids before discharge may also have affected the incidence of postoperative emesis during the 0- to 24-h observation period. Use of postoperative opioids did not have any effect on complete response rates in this patient population. We conclude that the prophylactic use of ondansetron reduces postoperative emesis in pediatric patients, regardless of the operant influential factors.

IMPLICATIONS

Postoperative nausea and vomiting often occur after surgery and general anesthesia in children and are the major reason for unexpected hospital admission after ambulatory surgery. Our study demonstrates that the prophylactic use of a small dose of ondansetron reduces postoperative vomiting in pediatric patients.

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 N2O: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.

Pediatric ambulatory anesthesia: role of parents

Preschool children depend on their parents for support and guidance in dealing with new or stressful situations. When requested, the parents should be allowed to support their children during ambulatory surgical procedures, especially during the induction of anesthesia. With proper understanding on our part, and with proper preparation and counseling, the parents can become our allies and help to smooth the experience for the child, for the staff, and for themselves. Future efforts should be directed at studying the effects of different methods of preoperative preparation and counselling on the parents' attitude and cooperation during induction.

Comparison of sevoflurane and halothane anesthesia in children undergoing outpatient ear, nose, and throat surgery

STUDY OBJECTIVE

To compare the induction, maintenance, and recovery characteristics of sevoflurane and halothane in pediatric ambulatory patients undergoing adenoidectomy with or without myringotomies (BMTs). To compare the hemodynamic effects of the two drugs.

DESIGN

Open, randomized study.

SETTING

University-affiliated pediatric hospital.

PATIENTS

39 ASA physical status I children aged 12 months to 12 years undergoing adenoidectomies with or without BMTs.

INTERVENTIONS

Patients were randomized to receive sevoflurane or halothane in 60% nitrous oxide (N2O) for induction and maintenance of anesthesia. All patients received midazolam 0.5 mg/kg orally as premedication, as well as fentanyl 1 mcg/kg intravenously (i.v.) immediately following induction. Tracheal intubation was facilitated with mivacurium 0.2 mg/kg i.v. Anesthesia was maintained with an end-tidal concentration corresponding to 1 minimum alveolar concentration (MAC) of each drug until the end of surgery, at which time all anesthetic gases were discontinued simultaneously. Emergence (extubation), recovery (Steward score = 6), and discharge times were compared among patients in both groups. Heart rate (HR) and mean arterial pressure were compared at predetermined intervals. Additional fentanyl was administered after full recovery was documented for an objective pain score of at least 6.

MEASUREMENTS AND MAIN RESULTS

Emergence from anesthesia was significantly faster (7.11 +/- 3.05 minutes vs. 9.58 +/- 5.12 minutes) and recovery (19.89 +/- 10.07 minutes vs. 31.08 +/- 9.81 minutes) more rapid in the sevoflurane group. However, there was no difference in the time to meet home discharge criteria (184 +/- 49 minutes vs. 189 +/- 48 minutes). HR was consistently maintained at or above baseline in the sevoflurane group. Blood pressure was significantly more depressed after fentanyl administration in the halothane group. There were no significant differences in the incidence of postoperative vomiting between the two groups.

CONCLUSION

Sevoflurane provides a faster anesthetic emergence and recovery than halothane in premedicated patients but it does not expedite meeting current home discharge criteria.

Mivacurium-induced neuromuscular blockade during sevoflurane and halothane anaesthesia in children

The neuromuscular blocking effects of mivacurium during sevoflurane or halothane anaesthesia was studied in 38 paediatric patients aged 1-12 yr. All received premedication with midazolam, 0.5 mg.kg-1 po and an inhalational induction with up to 3 MAC of either agent in 70% N2O and O2. The ulnar nerve was stimulated at the wrist by a train-of-four stimulus every ten seconds and the force of adduction of the thumb recorded with a Myotrace force transducer. Anaesthesia was maintained with a one MAC end-tidal equivalent of either volatile agent for five minutes before patients received mivacurium (0.2 mg.kg-1) iv. The onset of maximal blockade occurred in 2.4 +/- 1.26 (mean +/- SD) min with halothane and 1.8 +/- 0.54 min with sevoflurane (NS). Four patients failed to achieve 100% block (3 halothane, 1 sevoflurane). The times from injection to 5, 75, and 95% recovery during sevoflurane (9.8 +/- 2.6, 19.5 +/- 4.4, and 24.2 +/- 4.8 min) were greater than during halothane anaesthesia (7.2 +/- 2.2, 15.0 +/- 4.0, 19.2 +/- 4.9 min, respectively (P < 0.005). All patients demonstrated complete spontaneous recovery of neuromuscular function (T1 > 95%, T4/T1 > 75%) during the surgery which lasted 24-63 min. All patients showed clinical signs of full recovery of neuromuscular blockade (i.e., headlift, gag, or cough). Pharmacological reversal was not required. It is concluded that following a single intubating dose of mivacurium, the time to maximum relaxation was not different during halothane and sevoflurane anaesthesia; recovery times to 5, 75 and 95% twitch height were longer during sevoflurane anaesthesia and neuromuscular reversal was not necessary.

Age and the onset of desaturation in apnoeic children

Most patients undergoing general anaesthesia are apnoeic during laryngoscopy and tracheal intubation. This study determined the time until the onset of desaturation following pre-oxygenation in apnoeic infants, children, and adolescents. Fifty ASA physical status I patients, 2 days to 18 yr of age, were studied. The patients were stratified into one of five groups according to age: Group I, 0-6 mo; Group II, 7-23 mo; Group III, 2-5 yr; Group IV, 6-10 yr; and Group V, 11-18 yr. Following induction of anaesthesia with halothane via mask or intravenous barbiturates, the ability of the anaesthetist to ventilate the lungs via the mask was ascertained and paralysis was accomplished with vecuronium 0.1 mg.kg-1. Manual mask ventilation was maintained with oxygen and halothane. When end-tidal N2 decreased below 3% (minimum time two minutes), the face mask was removed. The time between the removal of the face mask and a decrease in oxygen saturation (SpO2) from 99-100% to 90% was measured. Manual ventilation was then resumed and the trachea intubated. Desaturation started earlier in infants than in two- to five-year-old children (96.5 +/- 12.7 sec vs 160.4 +/- 30.7 sec, P < 0.0001). Children became desaturated faster than adolescents (160.4 +/- 30.7 vs 382.4 +/- 79.9 sec, P < 0.0001). The time required to reach 90% saturation correlated well with age by linear regression analysis (r2 = 0.88, P < 0.0001). We conclude that the time to onset of desaturation following pre-oxygenation with mask ventilation increases with age in healthy apnoeic children.(ABSTRACT TRUNCATED AT 250 WORDS)

Jaw relaxation after a halothane/succinylcholine sequence in children

BACKGROUND

Lack of complete jaw relaxation after a halothane-succinylcholine sequence has been described in the literature. To date, however, most existing studies are retrospective, and lack agreement on the magnitude and incidence of this phenomenon. This prospective study examined the incidence and degree of incomplete jaw relaxation in 500 children who were given intravenous succinylcholine during halothane anesthesia.

METHODS

Five hundred consecutive unmedicated children received a minimum dose of 2 mg/kg intravenous succinylcholine after induction of anesthesia with halothane. The degree of jaw relaxation was assessed 45-60 s later by the same observer using a standardized clinical scale. The degree of relaxation was correlated with the type of surgical procedure, and the presence and intensity of fasciculations.

RESULTS

Complete relaxation (mouth opened easily and fully) occurred in 95.4% of study patients. Incomplete relaxation (firm manual separation required to open the mouth fully) was seen in 4.4% of the patients. One child (0.2%) had masseter muscle rigidity (mouth could not be fully opened but intubation possible). There were no incidents of trismus (teeth clamped shut and intubation via direct visualization impossible). The incidence of incomplete relaxation and masseter muscle rigidity did not correlate with the presence or degree of fasciculations or the type of surgical procedure. There were no clinical signs of a hypermetabolic state or myoglobinuria in any patient.

CONCLUSIONS

Incomplete jaw relaxation after a halothane-succinylcholine sequence is not uncommon in children, and is considered a normal response.

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.

Propofol anaesthesia in paediatric ambulatory patients: a comparison with thiopentone and halothane

The purpose of this study was to evaluate the haemodynamic changes during induction, as well as the speed and quality of recovery when propofol (vs thiopentone and/or halothane) was used for induction and maintenance of anaesthesia in paediatric outpatients. One hundred unmedicated children, 3-12-yr-old, scheduled for ambulatory surgery were studied. The most common surgical procedures performed were eye muscle surgery (42%), plastic surgery (21%), dental restoration (15%), and urological procedures (15%). The children were randomized to an anaesthetic regimen for induction/maintenance as follows: propofol/propofol infusion; propofol/halothane; thiopentone/halothane; halothane for both induction and maintenance. Succinylcholine 1.5 mg.kg-1 was used to facilitate tracheal intubation and N2O/O2 were used as the carrier gases in each case. All maintenance drugs were titrated according to the clinical response of the patient to prevent movement and/or maintain BP +/- 20% of baseline. Two patients (4%) who received propofol expressed discomfort during injection. The mean propofol dose required to prevent movement was 267 +/- 83 micrograms.kg-1.min-1. The overall pattern of haemodynamic changes, as well as awakening (extubation) times were not different among the four groups. Children who received propofol recovered faster (22 vs 29-36 min) (P < 0.05), were discharged home sooner (101 vs 127-144 min) (P < 0.05), and had less postoperative vomiting (4 vs 24-48%) (P < 0.05) than all others.(ABSTRACT TRUNCATED AT 250 WORDS)

Preoperative screening for pediatric ambulatory surgery: evaluation of a telephone questionnaire method

The purpose of this study was to determine whether preoperative screening of pediatric patients, accomplished by means of a preoperative telephone call to their parents, would decrease the rate of cancellation or postponement of ambulatory surgical procedures. Data from 5031 patients scheduled for ambulatory surgery were collected. During phase I of the study, when phone calls were attempted only during business hours, we contacted 805 of 1662 (48%) of patients' parents. The contact rate improved to 71% (2403 of 3369 patients) during phase II of the study, when phone calls were made in the evening, and parents were encouraged by the surgeons to call the ambulatory unit. Approximately 13% of the contacted parents reported a history of medical problems in their children. A preoperative anesthesia consultation was required in 2.8% of the patients whose parents were contacted. The rate of postponed or canceled surgery among those who could not be screened was 14.8%; among patients who were screened, it was 9.7% (P less than 0.001). Patients in the former group were more likely than those in the latter group to require inpatient care for monitoring or treatment of underlying medical problems (1.3% vs 0.3%, respectively; P less than 0.05). We conclude that a preoperative telephone interview is an effective method for screening pediatric ambulatory surgical patients.

Circulating endotoxin and tumor necrosis factor during pediatric cardiac surgery

OBJECTIVES

To study the hypothesis that endotoxin and tumor necrosis factor-alpha (TNF) are released into the circulation during the perioperative period in children undergoing open-heart surgery, and to assess the possible role of these factors in postoperative morbidity.

DESIGN

Prospective study.

SETTING

Operating room and ICU of a children's hospital.

PATIENTS

Twenty-four consecutive patients undergoing open-heart surgery for repair of congenital heart disease.

METHODS

Endotoxin and TNF concentrations were measured in blood samples withdrawn from patients at predetermined time points in the perioperative period. These concentrations were also measured in samples from all fluids and drugs administered to patients. Clinical variables were measured throughout the perioperative period, and the Pediatric Risk of Mortality score was calculated daily.

RESULTS

All of the preoperative control samples were negative for endotoxin and TNF. Endotoxin or TNF was detected in the blood of 21 (88%) of 24 patients during or after surgery. Endotoxin (ranging in concentrations from 0.32 to 438 pg/mL) was detected in the blood of 16 (67%) of the 24 patients. The majority of the samples positive for endotoxin were withdrawn during cardiopulmonary bypass and were associated with positive samples from the pump, from cardiotomy suction specimens, and from autotransfused blood. Blood cultures of all patients, except one, were negative for bacterial growth. TNF (ranging in concentrations from 3 to 132 U/mL) was detected in the blood of nine (37%) of the 24 patients. Patients positive for TNF had significantly (p less than .05) lower mean central venous pressures at 20 hrs after surgery and higher mean heart rates postoperatively compared with patients negative for TNF. No differences in other indicators of perioperative morbidity and intraoperative conditions were found, when the groups positive for endotoxin or TNF were compared with the groups negative for endotoxin or TNF, respectively.

CONCLUSIONS

Endotoxin and TNF are released into the circulation during and after pediatric open-heart surgery. TNF release may be related to some of the hemodynamic changes observed after open-heart surgery.

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.

Emergence airway complications in children: a comparison of tracheal extubation in awake and deeply anesthetized patients

We compared the differences in oxygen saturation and airway-related complications after tracheal extubation in pediatric patients undergoing elective strabismus surgery or adenoidectomy and/or tonsillectomy who were awake versus anesthetized. Seventy otherwise healthy patients between 2 and 8 yr of age were studied. Anesthesia was induced with halothane or thiamylal and maintained with nitrous oxide and halothane. After induction of anesthesia, the patients were randomly assigned to group 1 (awake extubation) or group 2 (anesthetized extubation). Oxygen saturation was measured continuously and recorded 10 min before extubation and at 1, 2, 3, 5, 7, 10, 15, 20, 25, and 30 min after tracheal extubation. Supplemental oxygen was administered when oxygen saturation values were less than 90% while breathing room air. Oxygen saturation levels were higher in group 2 than in group 1 at 1, 2, 3, and 5 min after extubation. There were no differences between the two groups in the number of patients requiring supplemental oxygen. The incidence of airway-related complications such as laryngospasm, croup, sore throat, excessive coughing, and arrhythmias was not different between the two groups. We conclude that the anesthesiologist's preference or surgical requirements may dictate the choice of extubation technique in otherwise healthy children undergoing elective surgery.

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.

Propofol: effective dose and induction characteristics in unpremedicated children

The induction dose, induction characteristics, and cardiovascular and respiratory effects of propofol were studied in 90 unpremedicated children 3-12 yr old. Propofol in a dose of 1-3 mg.kg-1 was injected in an antecubital vein over 10-30 s. Successful induction was defined by loss of eyelash reflex occurring within 50 s of the conclusion of propofol injection and followed by subsequent acceptance of face mask without excessive movement. The effective dose of propofol resulting in loss of eyelash reflex in 50% (ED50) and 95% (ED95) of children were 1.3 (1.1-1.4) and 2.0 (1.7-2.6) mg.kg-1 (95% confidence interval). The corresponding ED50 and ED95 for a successful induction that included acceptance of face mask were 1.5 (1.3-1.7) and 2.3 (2.1-3.0), respectively. There was a 6.6% incidence of mild to moderate pain on injection and a 12.7% incidence of involuntary movement. Apnea (cessation of breathing greater than 20 s) was seen in 21% of patients. Blood pressure decreased by more than 20% of baseline value in 48% of patients who received halothane (1-3%) after the bolus injection of propofol. It is concluded that propofol is an effective induction agent in children. A dose of 2.5-3.0 mg.kg-1 is recommended to ensure a smooth transition to an inhalational maintenance technique. The use of antecubital veins is associated with a low incidence of pain on injection.

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.

Timing of caudal block placement in relation to surgery does not affect duration of postoperative analgesia in paediatric ambulatory patients

The purpose of this study was to determine if the timing of caudal block placement in relation to surgery affected either the duration of postoperative pain relief or the discharge time in children undergoing brief ambulatory surgical procedures. Forty ASA physical status I or II children ages 18 mo to 11 yr were randomly assigned to one of two groups. Group 1 patients received a caudal block with 0.5 ml.kg-1 of bupivacaine 0.25 per cent following the induction of anaesthesia but before the onset of surgery. Group 2 patients received a similar block at the completion of surgery but before emergence from general anaesthesia. An experienced observer, who was not aware of the timing of block placement, observed all patients from arrival to the post-anaesthetic recovery room until discharge from the ambulatory surgery unit. Pain was assessed at five-minute intervals using an Objective Pain Scale. No statistically significant differences were noted between Group 1 and Group 2 patients with regard to their postoperative pain/discomfort scores, the need for postoperative narcotic analgesia, or the time required for either group to meet standard discharge criteria. It is concluded that the duration of postoperative analgesia is not impaired by placing the caudal block prior to the start of a brief surgical procedure.

A comparison between bupivacaine instillation versus ilioinguinal/iliohypogastric nerve block for postoperative analgesia following inguinal herniorrhaphy in children

This study compared the postoperative pain relief provided by simple instillation of bupivacaine into a hernia wound with that provided by ilioinguinal/iliohypogastric (IG/IH) nerve block. Sixty children undergoing inguinal hernia repair under general anesthesia were randomized to receive 0.25 ml/kg of 0.25% bupivacaine for either IG/IH nerve block or up to 0.5 ml/kg of the same solution for instillation nerve blocks. In the postanesthesia care unit (PACU), a trained blinded observer evaluated the patient's level of postoperative pain using a standardized 10-point objective pain scale. Fentanyl 1-2 micrograms/kg was administered intravenously to any child scoring 6 or more points on the pain scale. The difference in pain scores among the two groups were compared. The two groups were not significantly different in age, duration of surgery, or anesthesia. There was no significant difference between patients who received the two treatment modalities in their pain scores, analgesic requirements in the PACU, recovery times, and discharge times. These results demonstrate that the simple instillation of local anesthetics into a wound provides postoperative pain relief following hernia repair, which is as effective as that provided by intraoperative IG/IH nerve block.

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.

Low-dose intramuscular ketamine for anesthesia pre-induction in young children undergoing brief outpatient procedures

The authors sought to determine whether intramuscular ketamine (2 mg/kg) would facilitate inhaled induction of anesthesia in those children who are uncooperative. Thirty-five children were anesthetized with halothane and nitrous oxide for insertion of tympanotomy tubes. Twenty of those children were deemed by the anesthesiologist to be uncooperative and received 2 mg/kg of ketamine im prior to induction of anesthesia. The onset time (time from ketamine administration until induction of inhaled anesthesia could be started) was 2.7 +/- 0.3 min. The quality of the subsequent acceptance of inhaled induction with halothane was excellent in 61% of the patients and adequate in the remaining 39%. The recovery and discharge times were compared with those observed in 15 matched children who accepted induction of anesthesia via a mask without the use of ketamine. Recovery time was not prolonged, but home discharge was delayed by an average of 13 min in the ketamine group (P less than 0.04). Low-dose im ketamine was found to be an acceptable pre-induction drug in young children who are uncooperative for an inhaled induction of anesthesia.