Lynn M. Broadman

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.

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 patients 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.

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.

Metoclopramide Reduces the Incidence of Vomiting Following Strabismus Surgery in Children

This randomized, double-blind study evaluated the efficacy of metoclopramide administered at the completion of surgery as an antiemetic agent in pediatric patients undergoing ambulatory strabismus surgery; 126 unpremedicated ASA Physical Status 1 and 2 children ranging in age from 2 to 18 yr served as subjects. All received general anesthesia with halothane, N2O, and O2; tracheal intubation was facilitated with intravenous (iv) atracurium 0.5 mg/kg. Intravenous atropine 0.02 mg/kg and lactated Ringers solution with 5% dextrose equivalent to 4 h of maintenance fluids were administered during surgery. Neither opioids nor droperidol were given intraoperatively. At the completion of surgery, residual muscle paralysis was reversed with atropine 0.02 mg/kg (maximum dose 1.0 mg) and neostigmine 0.07 mg/kg (maximum dose 5.0 mg), and the stomach was decompressed prior to tracheal extubation. After the patient had been transferred to the postanesthesia recovery room (PARR) either metoclopramide 0.15 mg/kg or normal saline was administered intravenously to the children over a 1-min period. A research associate monitored the children for the incidence of post-operative vomiting and the time required for each child to meet discharge criteria from Short Stay Recovery Unit (SSRU). If a child vomited more than three times in both the PARR and SSRU, the vomiting was construed to be severe and the patient was offered further antiemetic treatment with iv droperidol 70 micrograms/kg. The incidence of postoperative vomiting in the metoclopramide group was 37% versus 59% in the placebo group (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Fentanyl uptake by the scimed membrane oxygenator.

With the initiation of cardiopulmonary bypass (CPB), using a membrane oxygenator, the drop in circulating fentanyl concentration is greater than can be attributed to dilution alone. This study examined the Scimed brand (2A-800) membrane oxygenator as a site of fentanyl binding. Initial experiments used an assembled CPB circuit. Subsequent dissection and analysis of the oxygenator revealed that the silicone-based membrane sheets were the primary site of fentanyl binding. The silicone-containing waterproof wrapper was also responsible for 1% to 2% of fentanyl binding. Binding of fentanyl to the Scimed membrane oxygenator occurs at a rapid rate and continues until the membrane has taken up 130 ng/cm2 of membrane surface area. The interaction is complete by 15 to 30 minutes if suprasaturated concentrations are used. Samples of membrane material with a surface area of 1 cm2 were also studied. Isolated membrane squares in a nonmoving prime solution required two hours for saturation at the same fentanyl concentrations as the intact membrane with circulating prime. Introduction of motion to the priming solution accelerated the rate of fentanyl binding by the isolated membrane squares to a rate similar to the intact membrane. Motion also provided results similar to those previously reported using different analysis techniques. Therefore, this method of studying fentanyl-membrane interactions using samples of membrane and tritiated fentanyl is a valid model for the intact membrane oxygenator in the assembled bypass circuit. In addition to solution movement, fentanyl concentration of the priming solution was also found to affect the rate of fentanyl uptake. When fentanyl concentrations were used which were insufficient to achieve saturation of the membrane (10 ng/mL and 20 ng/mL), the rate of uptake was slowed. Binding of all available fentanyl under these conditions occurred within three hours. There is potential modification of this interaction by several clinically relevant factors, including temperature, pH, protein content of prime solution, and other drugs. These areas require further study before the saturation data are applied to clinical practice.

Anaesthesia for diagnostic muscle biopsy in an infant with Pompe's disease.

The anaesthetic management of children with glycogen-storage disease type lia (Pompe’s disease) presents a variety of challenges. A modification of a femoral nerve block, the inguinal paravascular block, as described by Winnie, was used in conjunction with intravenous ketamine to provide anaesthesia for a diagnostic muscle biopsy in a 5.5-month-old infant with Pompe’s disease. A peripheral nerve stimulator was used to locate the femoral nerve in lieu of eliciting a paraesthesia.RésuméLa conduite anesthésique des enfants atteints de maladie d’entreposage de glycogène de type lia présente une variété de défis. Une modification du block du nerf fémoral, le block paravasculaire inguinal telle que décrite par Winnie, a été utilisée simultanément avec l’induction intraveineuse de kétamine afin de fournir l’anesthésie pour une biopsie musculaire diagnostique chez un enfant âgé de 5.5 mois atteinte d’une maladie de Pompe.Un stimulateur nerveux périphérique était utilisé afin de localiser le nerf fémoral et de provoquer la pares-thésie.

Oral clonidine and postoperative pain.

We enjoyed reading the article entitled “Oral Clonidine Premedicabon Reduces Postoperative Pain in Children” by Mikawa et al. (1). While we believe their study has demonstrated that clonidine (4.0 pg/kg) induces sedation and may reduce postoperative pain and discomfort in infants and children, we suspect that the use of our objective pain scale (OPS) may have introduced considerable error into the assessment of postoperative pain and discomfort in the study population and may have caused the investigators to interpret sedation to be synonymous with analgesia. The OPS was designed for use in unpremeditated patients. It was validated against the linear analog pain scale in a group of unpremedicated adolescents undergoing arthroscopic knee surgery (2). The interobserver reliability of the OF’S has also been validated (3). The OF’S has also been used by several recognized investigators (e.g., Berde, Ecoffey, Lerman, Watcha, and others) in more than 25 peer-reviewed, double-blind studies to evaluate the postoperative pain and discomfort of pediatric patients. In all cases, statistical significance was obtained using both parametric and nonparametric analytic techniques. Since the scale has never before been tested in premeditated patients, it is likely that children undergoing relatively painless procedures such as strabismus surgery would have a statistically significant reduction in their OPS scores if they were premeditated with a vasodilator and a hypnotic drug and compared with unpremedicated controls.

Ring Block of the Penis: A Proven Addition to Multimodal Pain Relief for Newborn Circumcision

* Abbreviations: EMLA — : eutectic mixture of local anesthetic RB — : ring block Pain in the neonatal period has both acute and chronic consequences. Increased awareness regarding the negative aspects of using narcotic analgesics to control procedural pain in infants and children favors the use of alternative techniques. In healthy neonatal boys, circumcision represents their first exposure to a procedure with the potential for significant pain. The goal of everyone involved in the performance of neonatal circumcisions must be to use techniques that allow this procedure to be performed with minimal discomfort to the infant while at the same time optimizing the risk/benefit ratio between the provision of anesthesia or analgesia and patient safety. In this month’s edition of Pediatrics , Sharara-Chami et al1 present their study entitled “Combination Analgesia for Neonatal Circumcision: A Randomized Controlled Trial,” in which they demonstrate that multimodal anesthesia and analgesia techniques are superior to the topical of a eutectic mixture of local anesthetic (EMLA). The authors found that the best combination for newborn circumcision anesthesia and analgesia was the use of EMLA cream, followed by sucrose administration and then a penile block with plain lidocaine before the onset of the procedure. Sharara-Chami et al1 used EMLA … Address correspondence to David A. Rosen, MD, FAAP, Department of Anesthesiology, West Virginia University, PO Box 8255, 1 Medical Center Dr, Morgantown, WV 26506-8255. E-mail: rosend{at}wvumedicine.org