Around and about the ASA
Monday PM: Pediatric Anesthesia, Pediatric Pain & General Pediatrics
Thirty abstracts were presented during this session, what follows are a few of the highlights. There were a number of studies looking at side effects and safety issues with inhalation anesthesia. Three studies were presented looking at emergence agitation following inhalation anesthesia. Cravero and colleagues (1247) from Dartmouth-Hitchcock Medical Center looked at 32 patients undergoing non-painful procedures with inhalation anesthetics and found a much higher incidence of emergence agitation with sevoflurane (30%) compared to halothane (0%). Finkel et al (1252) from Children’s National Medical Center and Galinkin et al (1253) from Children’s Hospital of Philadelphia each independently found that intraoperative nasal fentanyl in a 2mcg/kg dose effectively decreased the incidence of emergence agitation postoperatively in both unpremedicated patients (Finkel) and midazolam/acetaminophen premedicated patients (Galinkin). Further, the later study demonstrated that intranasal fentanyl reduced emergence agitation with either halothane or sevoflurane. Byhahn (1246) and colleagues from JW Goethe University examined the danger of occupational exposure to sevoflurane and nitrous oxide. They found that both sevoflurane and nitrous oxide were detected in concentrations higher than NIOSH regulations permit during induction. However, when looked at for the entire period of surgery (induction + maintenance) these levels did not violate NIOSH recommendations.
Two abstracts examined intubating concerns for children. Fine et al (1251) from Children’s Hospital of Pittsburgh looked at the effectiveness of controlled ventilation using cuffed versus uncuffed tubes in infants. This study demonstrated that cuffed endotracheal tubes are safe and have less air leak than uncuffed tubes. However, they noted no difference in end tidal carbon dioxide or end-expiratory tidal volumes with cuffed vs. uncuffed tubes. Uezono and colleagues (1246) from Stanford University looked at microtia as a predictor of difficult airway. They found bilateral microtia to be a “sentinel sign” of a difficult airway in school age children. 36% of patients with bilateral microtia had difficult laryngoscopies compared with 4% of children with unilateral microtia and 0% of age-matched controls.
Various issues in pediatric pain management were also examined in this session. Three studies looked at caudal or epidural ropivicaine. Ross et al (1270) from Duke Medical Center looked at the effectiveness of 0.1, 0.2 and 0.3% caudal ropivicaine with 1:200,000 epinephrine for elective groin and lower abdominal surgery in children under 7 years of age. Surprisingly, in their interim analysis, they found no difference between study groups for a 0.75cc/kg dose in terms of effectiveness, duration of blockade and time to discharge. Also looking at caudal ropivicaine, Roelants et al from St. Luc Hospital, Brussels, Belgium (1269) compared caudal ropivicaine with and without epinephrine. Their study demonstrated that ropivicaine with 1:200,000 epinephrine effectively reduced the maximum plasma concentration and increased the time to peak plasma concentration of ropivicaine by reducing its local vasodilatory. McCann (1262) and colleague from Children’s Hospital, Boston, examined the pharmacokinetics of lumbar epidural ropivicaine. After drawing multiple venous samples on 7 infants and 11 toddlers after administration of 1.7mg/kg ropivicaine by single lumbar epidural bolus, they found that ropivicaine clearance matures by 3-12 months of age. They also noted that 1.7mg/kg ropivicaine without epinephrine generates safe plasma concentrations. In a study looking at local anesthetics for chronic pain, Lin and colleagues (1258) from Stanford University demonstrated a favorable response to intravenous lidocaine for children with refractory mucositis pain. After initiating a lidocaine infusion at 1mg/kg/hr, the 12 children enrolled in this study had significant decreases in both PCA use and average visual analogue pain scores (8.3 ± 0.9 to 1.8 ± 1.2). Finally, Munro and colleagues (1263) from the University of Michigan looked at the effectiveness of the addition of low dose Ketorolac (0.5 mg/kg every six hours for 36 hours) to PCA morphine for children who have undergone posterior spinal fusions. They found that patients in the low dose ketorolac group had improved quality of analgesia (lower overall pain scores) and a reduced morphine requirement without an increase in NSAID side effects.
Tuesday AM: Panel on pain management in children
Reported by Allison K. Ross, MD, Duke University Medical CenterThe ASA was fortunate to have a panel on Tuesday morning 10/17 that presented several options for the management of pain in children. This panel was moderated by Dr. Mashallah Goodarzi of Los Angeles Children’s Hospital who also contributed with a discussion of neuraxial opioids and their role in the management of pediatric pain. The use of peripheral nerve blocks and the advantages of using peripheral nerve blocks for pediatric pain management were presented by Dr. Allison Kinder Ross of Duke University Children’s Health Center. Dr. Patrick Birmingham of Children’s Memorial Hospital in Chicago discussed the use of PCA in children with the historical perspective as well as extensive data on treatment options and recent advances. Dr. Rukaiya Hamid of UC Irvine presented practical information on central nerve blocks and their contribution to the management of pediatric pain. To finish the discussion, Dr. Steven Hall, also hailing from Children’s in Chicago, discussed the management of chronic pain in children with cancer.
Questions following these discussions centered on the use of axial opioids and times to discharge of children. There were many opinions as to the use of epidural fentanyl versus epidural morphine. These discussions then moved to the use of clonidine and its availability to the members in the audience.
The presentations were well received and the question/answer session was informative for all.
Tuesday AM: Pediatric Anesthesia: General pediatrics and pediatric cardiac anesthesia
Reported by Jeffrey Galinkin, MD, Children’s Hospital of Philadelphia Thirty abstracts were also presented on Tuesday afternoon on a wide range of topics; some of the highlights follow. A number of abstracts during this session looked at monitoring of children with both old and new techniques. Belani et al (1278) of the University of Minnesota examined the Vasotrac (Medwave Inc., Arden Hills, MN) non-invasive radial arterial pressure monitor. This study demonstrated that blood pressure measured by this device correlated well with oscillometric readings in children 2-12 undergoing surgery. They note that to effectuate the best readings a shorter Velcro strap is required to adjust to the pediatric arm size. The Bispectral Index (BIS) monitor was examined in 3 abstracts. Both Davidson et al (1283) of Children’s Hospital Boston and Watcha and colleagues (1300) of Children’s Hospital of Philadelphia showed that the BIS monitor is useful in determining depth of anesthesia in children. However, Watcha noted the BIS value was a poor predictor of patient movement and hemodynamic values. Additionally, Davidson found poor correlation between BIS values and depth of anesthesia in infants. To further the debate on the utility of the BIS monitor, Bannister and colleagues (1276) of Emory University reported on the effect of BIS monitoring on emergence, PACU discharge, and anesthetic utilization in children receiving sevoflurane anesthesia. 76 subjects were randomized to a standard ASA monitoring group or a standard ASA monitoring + BIS group (BIS 45-60 during maintenance and 60-75 for the last 15 minutes of surgery). Her group found no statistically significant difference between groups in time to first response, time to extubation or time to meet PACU discharge criteria. Further, there was no difference in anesthetic agent utilization or in hemodynamic variables during the surgical procedure. In another interesting study, Wellis et al (1301) from Stanford University found no effect of 0.5% isoflurane in conjunction with a remifentanil infusion on SSEP values (N1 latencies or N1-P1 amplitudes) when compared to a propofol/remifentanil technique.
Emery et al (1284) and Rowney et al (1296) both of the Hospital for Sick Children in Toronto looked at the safety of carbon dioxide pneumoperitoneum in laparoscopic surgery in infants. They found that intra-abdominal pressures up to 15mm to have no effect on cardiac index or middle cerebral artery blood flow velocities. Also in infants and neonates, Blum and colleagues (1279) from Children’s Hospital Boston looked at the safety of remifentanil compared to halothane in 60 patients undergoing pyloromyotomy. They found remifentanil to be a safe alternative to traditional inhaled anesthetics without significantly increasing extubation or discharge times. In the second part of this study Galinkin and colleagues (1287) looked at pneumocardiograms before and after anesthesia in infants undergoing pyloromyotomy. They found no difference in the incidence of apnea or the incidence of abnormal pneumocardiogram studies postoperatively between remifentanil and halothane study patients. Additionally, they found that apnea and abnormal pneumocardiogram studies both occur in the 12 hours after anesthesia regardless of anesthesia technique.
A number of abstracts looked at some important cardiovascular issues associated with cardiac and non-cardiac surgery. Chew et al (1280) of Skejby Sygehus, Aarhus, Denmark looked at the effect of modified ultrafiltration (MUF) on cytokine production following pediatric cardiac surgery. Their findings suggested that MUF has no significant influence on cytokine release into peripheral blood and that the improvement in clinical outcome that patients who underwent MUF saw was related to factors other then cytokine release. Odegard and colleagues (1293) of Children’s Hospital Boston looked at coagulation factor abnormalities in single ventricle patients prior to undergoing the Fontan procedure (already had undergone a stage I repair). In the Fontan patients they looked at, factors II, V, VII, X, protein C, plasminogen and ATIII were all significantly lower than age matched healthy controls. Thus they conclude that multiple pro- and anticoagulant factor abnormalities exist which may be the predisposing reason for these children having an increased frequency of thromboembolic phenomenon in the postoperative period. In a similar population, Ririe et al (1295) of Wake Forest University looked at the pharmacokinetics of e-aminocaproic acid (eACA) in children undergoing surgical repair of congenital heart defects. His group found that eACA follows a two-compartment pharmacokinetic model in children similar to that seen in adults following a loading dose and a continuous infusion prior to and after surgery with cardiopulmonary bypass. Unlike adults, these children have a larger volume of distribution and faster central compartment clearance and benefit from larger bolus doses and a higher maintenance infusion rates. Munro and colleagues (1290) of Columbia University presented a study looking at a drug traditionally used in the cardiac arena for non-cardiac use. Their study examined the use of aprotinin (loading dose 240mg/m2 , continuous infusion 56 mg/m2 /hr) to decrease blood loss in pediatric craniofacial surgery. Three groups were looked at: A received aprotinin; C was a control group (same surgery, no aprotinin); M was a historical age-matched group. 30 patients were looked at in this non-randomized partially retrospective study. Group A lost an average of 247cc’s of blood and only 50% of these patients required intraoperative transfusion as opposed to group C and M who all required transfusion for a blood loss of 550 and 540 cc’s respectively. They concluded that aprotinin may play a useful role in craniofacial surgery but that a prospective randomized controlled study would need to be done to demonstrate actual benefit.
Wednesday AM: Breakfast Panel, Section on Anesthesiology of the American Academy of Pediatrics: Pediatric Anesthesia, Here, There and Yon.
Reported by Tom Mancuso, MD, Children’s Hospital, Boston.
Drs. Rita Agarwal (Children’s Hospital Denver), Lynne Maxwell (Johns Hopkins Medical Institutions) and Joe Tobias (University of Missouri -Columbia) discussed anesthesia for children for minimally invasive surgery, for procedures out of the operating room and for office-based procedures, respectively. Dr. Agarwal began the morning with a review of what types of surgical procedures were now being performed through scopes or with newer, minimally invasive techniques. Among the more difficult situations which arise during minimally invasive surgery are those associated with thoracic procedures. Dr. Agarwal reviewed the physiologic derangements which accompany one-lung anesthesia in children and also discussed the various options for lung isolation available for children. Size considerations become especially important in one lung anesthesia when children are involved. Dr. Agarwal mentioned that double-lumen endotracheal tubes are not available for small children because of the prohibitive small size of the central airways in smaller children and various bronchial blockers used to isolate one lung must be positioned with exquisite care because of the short distance between the various branches of the bronchi. Dr. Agarwal reviewed various strategies for maximizing gas exchange and minimizing hemodynamic effects of one lung ventilation during thorascopic procedures. Laparoscopic surgery was also discussed by Dr. Agarwal. She reviewed the effects on end-tidal C02 measurements and the additional surgical risks, such as difficulty controlling bleeding, posed by performing procedures through fiberoptic scopes.
Dr.Lynne Maxwell then reviewed important considerations when providing anesthesia for children outside of the operating room setting. The most challenging of the environments she discussed was the MRI suite. In providing anesthesia for children undergoing MRI scans, in addition to other problems seen in outfield anesthesia such as: working in an unusual and distant environment with people unfamiliar with the needs of the anesthesiologists, using equipment perhaps different from that used daily in the OR and perhaps not as well maintained and being distant from the patient there are the special problems posed by THE MAGNET. Nearly everything we as anesthesiologists do is affected by the magnetic field. Monitoring must be adapted and may be made inaccurate by the magnetic field, all equipment must be non-ferromagnetic and once the scan is underway we join the radiology personnel in leaving the suite itself, monitoring our patient at a distance. MRI-compatible anesthesia machines and equipment are available at a cost; and at institutions where anesthesia for MRI’s is frequent, the investment in such equipment may be justified. Another difficult location where the pediatric anesthesiologists are needed was discussed by Dr. Maxwell and included radiation therapy. Here, children must be absolutely immobile for the treatments, which generally last only minutes. The treatments are generally given for 20-40 consecutive days and often as treatment progresses; the children become progressively more debilitated and poorly nourished. In many cases for radiation therapy, the child’s position is other than supine, often creating airway difficulties for the anesthesiologist. Also, in radiation therapy, the child is left alone for the duration of the radiation, often observed only via television camera.
Dr. Joseph Tobias discussed office-based anesthesia for children. He first mentioned the problems, which have been encountered thus far with this practice in adults. He mentioned the increased mortality reported from Florida, which led to the legislature temporarily halting the practice of certain office-based procedures until safety could be improved. Dr. Tobias then reviewed the types of procedures which children might undergo in the office or non-hospital setting such as radiologic studies and procedures in free-standing facilities, dermatologic procedures and others. As an indication of the rapid growth in this area, Dr. Tobias mentioned the increase in size of SOBA, The Society for Office-Based Anesthesia which grew from the 10 members who founded it in 4 years ago to nearly 500 members today. Dr. Tobias emphasized the importance of adequate systems for the provision of anesthesia in the office setting. In view of the newness and isolation of office-based anesthesia, Dr. Tobias also spoke of the importance of establishing standards for equipment, monitoring, staffing, and recovery as they are for hospital-based practice in order to assure children do not receive inadequate care in the office setting.
Wednesday PM: What’s New in Pediatric Pharmacology
Reported by Tom Mancuso, MD, Children’s Hospital, Boston.
Dr. Carolyn Bannister, Egleston Children’s Hospital, Atlanta, moderated the ASA panel. An indication of the interest in pediatric anesthesia topics, the panel, which was scheduled at the conclusion of this years ASA, was very well attended.
The first speaker, Dr. Jerrold Lehrman, Hosptial for Sick Children, Toronto, reviewed new agents for the induction of general anesthesia. The use of propofol and sevoflurane were reviewed and clinical utility of these two agents compared. Dr. Lehrman discussed the use of maneuvers to minimize the pain felt by patients upon injection of propofol including lidocaine administration, cooling the propofol prior to administration and combination of propofol with thiopental. He also compared the use of sevoflurane, propofol and thiopental with regard to their effects on emergence.
Dr. Barbara Brandom, Children’s Hospital of Pittsburgh, reviewed the current data on the use of newer muscle relaxants, rocuronium and rapacuronium. She compared speed of onset for use of these relaxants for intubation as well as the duration of action and minimum time before reversal of neuromuscular blockade can be undertaken. Dr. Brandom summarized current information on the clinical use of these two no-depolarizing muscle relaxants. In her review of the recent clinical information on these two agents, Dr. Brandom discussed the problem of bronchospasm with the use of rapacuronium as well as possible mechanism for this entity.
Dr. Ann Lynn, Children’s Hospital, Seattle, spoke on the topic of opioids in pediatric anesthesia. She limited her remarks to the use of remifentanil in children and newborns. Dr. Lynn discussed published information in the clinical use of this new synthetic opioid in children relating to its efficacy, safety and effects on emergence times. She also discussed several interesting cases of administration of this new opioid to infants who were receiving mechanical ventilation for periods of greater than 24 hours. The infants were ready for extubation within 20 minutes of the time the remifentanil infusion was stopped.
Dr. Thomas Mancuso from Children’s Hospital in Boston discussed local anesthetic agents and adjuncts in children. he reviewed information regarding the use of caudal and epidural ropivacaine including a discussion of the data about the relative toxicity of this new local anesthetic. Dr. Mancuso also discussed caudal administration of clonidine or ketamine in combination with the local anesthetics bupivacaine or ropivacaine.
Dr. Joseph Tobias, University of Missouri-Columbia, discussed the use of new cardiovascular agents in children. He reviewed work-comparing nicardipine to sodium nitroprusside for hypotension in the operating room. He reviewed the use of this calcium channel antagonist in various intraoperative settings including cardiac surgery and posterior spinal fusions. Blood pressure control has been achieved with both continuous infusions as well as with bolus administration.
Dr. Joseph Tobin, Wake Forest University School of Medicine, also discussed fenoldapam, a selective dopamine-1 agonist recently made available for IV use. Stimulation of the DA-1 receptor leads to vasodilation, decreased SVR with lowering of blood pressure and increased cardiac output. Its kinetic parameters allow for rapid titration. Dr. Tobias reviewed the use of this agent in the treatment of urgent or emergent hypertension and also the evidence for a renal protective effect.
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