Mary F. Rabb

A randomized multicenter study of remifentanil compared with halothane in neonates and infants undergoing pyloromyotomy. I. Emergence and recovery profiles

Pyloric stenosis is sometimes associated with hemodynamic instability and postoperative apnea. In this multicenter study we examined the hemodynamic response and recovery profile of remifentanil and compared it with that of halothane in infants undergoing pyloromyotomy. After atropine, propofol, and succinylcholine administration and tracheal intubation, patients were randomized (2:1 ratio) to receive either remifentanil with nitrous oxide and oxygen or halothane with nitrous oxide and oxygen as the maintenance anesthetic. Pre- and postoperative pneumograms were done and evaluated by an observer blinded to the study. Intraoperative hemodynamic data and postanesthesia care unit (PACU) discharge times, PACU recovery scores, pain medications, and adverse events (vomiting, bradycardia, dysrhythmia, and hypoxemia) were recorded by the study’s research nurse. There were no significant differences in patient age or weight between the two groups. There were no significant differences in hemodynamic values between the two groups at the various intraoperative stress points. The extubation times, PACU discharge times, pain medications, and adverse events were similar for both groups. No patient anesthetized with remifentanil who had a normal preoperative pneumogram had an abnormal postoperative pneumogram, whereas three patients with a normal preoperative pneumogram who were anesthetized with halothane had abnormal pneumograms after.

A randomized multicenter study of remifentanil compared with halothane in neonates and infants undergoing pyloromyotomy. II. Perioperative breathing patterns in neonates and infants with pyloric stenosis

Although former preterm birth infants are at risk for postoperative apnea after surgery, it is unclear whether the same is true of full-term birth infants. We evaluated the incidence of apnea in 60 full-term neonates and infants undergoing pyloromyotomy both before and after anesthesia. All subjects were randomized to a remifentanil- or halothane-based anesthetic. Apnea was defined by the presence of prolonged apnea (>15 s) or frequent brief apnea, as observed on the pneumocardiogram. Apnea occurred before surgery in 27% of subjects and after surgery in 16% of subjects, with no significant difference between subjects randomized to remifentanil or halothane anesthesia. This apnea was primarily central in origin, occurred throughout the recording epochs, and was associated with severe desaturation in some instances. Of the subjects with normal preoperative pneumocardiograms, new onset postoperative apnea occurred in 3 (23%) of 13 subjects who received halothane-based anesthetics versus 0 (0%) of 22 subjects who received remifentanil-based anesthetics (P = 0.04). Thus, postoperative apnea can follow anesthesia in otherwise healthy full-term infants after pyloromyotomy and is occasionally severe with desaturation. New-onset postoperative apnea was not seen with a remifentanil-based anesthetic.

Body Morphology and the Speed of Cutaneous Rewarming

BackgroundInfants and children cool quickly because their surface area (and therefore heat loss) is large compared with their metabolic rate, which is mostly a function of body mass. Rewarming rate is a function of cutaneous heat transfer plus metabolic heat production divided by body mass. Therefore, the authors tested the hypothesis that the rate of forced-air rewarming is inversely related to body size. MethodsIsoflurane, nitrous oxide, and fentanyl anesthesia were administered to infants, children, and adults scheduled to undergo hypothermic neurosurgery. All fluids were warmed to 37°C and ambient temperature was maintained near 21°C. Patients were covered with a full-body, forced-air cover of the appropriate size. The heater was set to low or ambient temperature to reduce core temperature to 34°C in time for dural opening. Blower temperature was then adjusted to maintain core temperature at 34°C for 1 h. Subsequently, the forced-air heater temperature was set to high (≈ 43°C). Rewarming continued for the duration of surgery and postoperatively until core temperature exceeded 36.5°C. The rewarming rate in individual patients was determined by linear regression. ResultsRewarming rates were highly linear over time, with correlations coefficients (r2) averaging 0.98 ± 0.02. There was a linear relation between rewarming rate (°C/h) and body surface area (BSA; m2): Rate (°C/h) = −0.59 · BSA (m2) + 1.9, r2 = 0.74. Halving BSA thus nearly doubled the rewarming rate. ConclusionsInfants and children rewarm two to three times faster than adults, thus rapidly recovering from accidental or therapeutic hypothermia.

Use of CobraPLA™ for airway management in a neonate with Desbuquois syndrome. Case report and anesthetic implications

We present the anesthetic management of an infant with Desbuquois syndrome (a rare form of micromelic dwarfism) with a possible difficult airway. The anesthetic implications of this syndrome are presented. The airway was managed with a new supraglottic device – the CobraPLA. Although intubation through this device was not possible in this instance, CobraPLA provided a satisfactory supraglottic airway. It was easy to insert and provided satisfactory conditions for positive pressure ventilation. The CobraPLA provides another option for airway management.

Caudal Regional Anesthesia, Ropivacaine Concentration, Postoperative Analgesia, and Infants

In this randomized, double-blind trial we evaluated the quality and duration of analgesia and motor effects after caudal block using 1 mL/kg of ropivacaine 0.1% (Group 1), 0.15% (Group 2), 0.175% (Group 3) compared to 0.2% (Group 4) in infants 1–12 mo old. Postoperatively, the number of infants who received pain medication differed among the groups (P < 0.0005). There were more infants in Groups 1 and 2 compared with Group 4 and there was no difference between Groups 3 and 4. In the postanesthesia care unit, infants in Groups 1 and 2 received more pain medication than did those in Group 4 (P = 0.0098). In the day surgery unit, there was a significant difference among the groups (P = 0.0326); infants in Groups 3 and 4 required no pain medication. The analgesia duration differed among the groups (P = 0.034). Infants in Groups 1 and 2 had a shorter duration, and there was no difference between Groups 3 and 4. Infants in Group 4 took longer to regain their motor power compared with those in Group 3 (P = 0.0347). We conclude that in infants, ropivacaine 0.175% provided postoperative analgesia and duration similar to that of ropivacaine 0.2%, whereas ropivacaine 0.1% and 0.15% did not, and it was associated with fewer motor effects.

Fatal Hydrocephalus in a Patient with Neurofibromatosis

To the Editor:-Anesthetic implications of neurofibromatosis may include airway, mediastid and vertebral neurofibromas, associated endocrine syndromes, and intracranial masses in 510% of patients. ’ Hydrocephalus is a rare manifestation of neurofibromatosis and is commonly descrihed during the first two decades of lie.’-* We present a case of acute postoperative hydrocephalus in a previously healthy 21-yr-old patient with neurofibromatosis. The patient presented for excision with bilateral flap closure of a 12-cm cutaneous neurofibroma of the posterior neck and back. He had another neurofibroma on a toe, cafe-au-lait spots, and no history of seizures or intracranial disease and was otherwise in good health. The 4-h anesthesia and surgery was uneventful, with careful prone positioning, and the patient was discharged, awake, from the recovery room. Over the next 6 h, the patient received hydrocodone (two tablets), promethazine (12.5 mg), morphine (4 mg), and promethazine (12.5 mg). One hour after the morphine-promethazine (12 h after surgery), the patient’s mother reported that the patient had a headache, had vomited, and may have had a seizure. At assessment, the patient was found to be unresponsive and was immediately intubated and resuscitated by an anesthesiologist who was on the floor at the time. Pupils were fixed and dilated, computed tomography showed severe obstructive hydrocephalus with transtentorial herniation, severe diffuse cerebral edema, and an illdefined area of decreased density in the right thalamus. Although a ventriculostomy was placed, the patient remained unresponsive and was declared brain dead the following day. The computed tomography findings were compatible with a diagnosis of aqueduct stenosis, and the cause of the acute increase in intracranial pressure was speculated to have resulted from a seizure. In retrospect, the presumed nausea, necessitating perphenazine 1 h before arrest, may have heralded an increase in intracranial pressure.