Halothane-morphine compared with high-dose sufentanil for anesthesia and postoperative analgesia in neonatal cardiac surgery

Congenital diaphragmatic hernia: developing a protocolized approach

BACKGROUND/PURPOSE

The purpose of this study was to evaluate the evolving outcome of newborns who have congenital diaphragmatic hernia (CDH) using a protocolized approach to management, which includes extracorporeal membrane oxygenation (ECMO) and to present the details of such a management protocol.

METHODS

A retrospective chart review was conducted of the neonatal outcome of near-term (>34 weeks' gestation) newborns with CDH all referred to the Royal Alexandra Hospital either before or after delivery. A protocol was developed that included antenatal assessment, the use of antenatal steroids, planned delivery, use of prophylactic surfactant, pressure limited gentle ventilation, permissive hypercarbia and hypoxia, and venovenous ECMO, if indicated.

RESULTS

Sixty-five infants with CDH were treated from February 1989 through August 1996. Twenty-three infants were inborn, 20 of whom were antenatal referrals. Overall, 51 of the 65 infants survived (78%). Thirteen of the 23 inborn infants survived with conservative management, and 10 required ECMO, of whom, eight were long-term survivors. Thirty-eight infants required ECMO, and 26 survived (68%), whereas there were only two deaths among the 27 conservatively treated infants. Eighteen of 20 inborn infants with an antenatal diagnosis survived, compared with 13 of 21 (62%) outborn infants. An antenatal diagnosis before 25 weeks' gestation was associated with a 60% survival rate. Sixty-three percent of infants whose best postductal PaO2 value before ECMO was less than 100 torr survived, and 7 of 11 infants with a best postductal PaO2 value of less than 50 torr before ECMO survived (64%). The average age at surgery progressively increased over time both for infants who did not require ECMO (1.3 days to 5.8 days; P = .01) and for infants who received ECMO (1.9 days to 8.2 days; P = .016).

CONCLUSIONS

The use of a protocolized management for infants with CDH has been associated with improving outcome in a population at high risk. The components (either separately or combined) of these protocolized approaches need to be tested in prospective trials to determine their true benefit. In addition, there is a need to evaluate prospectively the outcomes of infants with CDH born in ECMO centers compared with those infants born in other tertiary care neonatal units to determine the most appropriate management of the fetus with CDH.

Modifying infant stress responses to major surgery: spinal vs extradural vs opioid analgesia

Twenty-six infants due to undergo major abdominal or thoracic surgery under general anaesthesia were randomized to receive additional analgesia with group A) spinal/epidural analgesia; B) epidural analgesia or C) opioid analgesia with fentanyl. We wished to determine if spinal analgesia followed by epidural analgesia might result in more complete control of cardiovascular or stress responses than the other two treatment groups. Heart rate and blood pressure were recorded at five min intervals throughout surgery. Blood samples were taken for measurement of catecholamines and whole blood sugar on induction, 45 min after skin incision and at the end of surgery. Heart rate rose significantly at the start of surgery in groups B and C but not group A. Systolic blood pressures were higher in group C compared to A and B. The rise in plasma glucose concentrations was significantly different between the groups in the order C > B > A (P < 0.05). A similar trend was seen in the plasma adrenaline and noradrenaline concentrations but this failed to achieve significance due to the limited sample size.

Stress response and mode of ventilation in preterm infants

AIM

To assess the change in stress response in preterm babies changed from patient triggered ventilation (PTV) to conventional mandatory ventilation (CMV) and vice versa; to determine outcome in relation to stress hormone concentrations.

METHODS

A randomised controlled study was conducted in two district general hospital neonatal intensive care units. Thirty babies, treated initially with CMV, were randomly assigned to remain on CMV or to change to PTV. A second group of 29 babies, treated initially with PTV, were randomly assigned to remain on PTV or to change to CMV. The babies were less than 32 weeks of gestation, ventilated within 72 hours of birth, with clinical and radiological features compatible with respiratory distress syndrome (RDS). Stress hormone concentrations and clinical distress score were measured before and 20 minutes after allocation of mode of ventilation.

RESULTS

Babies changed from CMV to PTV had significantly reduced adrenaline concentrations (median change -0.4 nmol/l) compared with those who remained on CMV. There was no increase in adrenaline in babies changed from PTV to CMV. There were no significant changes in noradrenaline concentrations or clinical distress score. Babies who died had significantly higher adrenaline and noradrenaline concentrations than those who survived.

CONCLUSION

A change in mode of ventilation significantly reduces adrenaline concentrations. Raised catecholamine values are associated with a poor outcome.

Opioids in cardiac surgery: cardiopulmonary bypass and inflammatory response

After a brief overview of the history of narcotic use in anesthesia, the various opiates are reviewed mainly from a stress-reducing, antiinflammatory and hemodynamic perspective. The emphasis is placed on cardiac anesthesia.

Pain in the very preterm baby: 'suffer little children?'

Increases in medical expertise and technological advances have enabled the survival of very preterm babies who form a new and growing population. Comparisons between the foetus, full-term baby and the very preterm baby indicate that by the time the foetus is of 23 weeks gestation, many of the abilities, for example, sensing touch, hearing, seeing, moving and even learning may be common to all three. Thus, the very preterm infant who has been described as a unique organism, is not passive, but is a sentient being who is unlikely to survive without the medical and technical support of the Neonatal Intensive Care Unit (NICU) where he/she is exposed to frequent and regular medical procedures. Many of these procedures would be, for any normal, fully developed human being at best uncomfortable and at worst painful. Reviews within the past 10 years have shown that the neurochemical, anatomic and functional systems of newborns are developed enough to perceive pain. More importantly, rat pup studies have indicated that not only may the very preterm baby experience pain but it may experience it more intensely than the more mature infant. Moreover, there may be serious consequences of repeated painful medical intervention. Alleviation of pain and/or distress in very preterm infants is, therefore, an important issue.

Neonatal circumcision and pain relief: current training practices

OBJECTIVE

We conducted a national survey of pediatric, family practice, and obstetrics and gynecology residency program directors to determine the curriculum content and predominant practices in US training programs with regard to neonatal circumcision and anesthesia/analgesia for the procedure.

METHODS

Residency directors of accredited programs were surveyed in two mailings of a forced response and short answer survey (response rate: 680/914, 74%; pediatrics 83%; family practice 72%; obstetrics 71%).

RESULTS

Pediatric residents were less likely than family practice [odds ratio (OR), 0.04; 95% confidence interval (CI), 0.02-0.08] or obstetrical (OR, 0.14; 95% CI, 0.08-0.23) residents to be taught circumcision. Training and local custom were rated as important determinants of medical responsibility for neonatal circumcision. Pediatric residents training in programs in which community pediatricians perform circumcisions were more likely to learn circumcision (OR, 39.0; 95% CI, 14.3-110.6) as were obstetric residents (OR, 79.0; 95% CI, 22.4-306.4) training in programs in which community obstetricians perform circumcision. In programs that teach circumcision, pediatric (84%; OR, 3.4; 95% CI, 1.7-7.1) and family practice (80%; OR, 2.7; 95% CI, 1.7-4.2) programs were more likely than obstetric programs (60%) to teach analgesia/anesthesia techniques to relieve procedural pain. Overall, 26% of programs that taught circumcision failed to provide instruction in anesthesia/analgesia for the procedure. Significant regional variations in training in circumcision and analgesia/anesthesia techniques were noted within and across medical specialties.

CONCLUSIONS

Residency training standards are not consistent for pediatric, family practice, and obstetrical residents with regard to neonatal circumcision or instruction in analgesia/anesthesia for the procedure. Training with regard to pain relief is clearly inadequate for what remains a common surgical procedure in the United States. Given the overwhelming evidence that neonatal circumcision is painful and the existence of safe and effective anesthesia/analgesia methods, residency training in neonatal circumcision should include instruction in pain relief techniques.

Pharmacologic pain management in children: a review of intervention research

In the past decade, an explosion of interest in pediatric pain has resulted in the proliferation of research studies. This review examines 41 studies that focus on pharmacologic interventions in children during the last decade. Criteria for inclusion in this paper were studies that (1) tested a pharmacological intervention prospectively, (2) were conducted with children only, (3) had a sample size over 30, (4) randomly assigned participants to two or more groups, and (5) provided sufficient methodological and statistical detail for critique. Studies focused on postoperative and procedural pain, were conducted most frequently with pre-school-aged children or older, and demonstrated the efficacy of pharmacologic interventions.

The use of intravenous opioids to provide analgesia in critically ill, premature neonates: a research critique

The intravenous (i.v.) administration of opioids to neonates is a common method of providing analgesia in the intensive care setting. This paper reviews and critiques the studies that have investigated this intervention. The studies are grouped into four major areas: pharmacokinetic studies; i.v. opioids for anesthesia; i.v. opioids for sedation or analgesia in mechanically ventilated neonates; and cardiorespiratory effects of i.v. opioids. An attempt is made to synthesize current knowledge about the analgesic effects and side effects associated with the use of i.v. opioids in neonates. The intent is to stimulate additional research on the management of neonatal pain using opioid analgesics.

Measurement of neonatal responses to painful stimuli: a research review

The measurement of neonatal responses to painful stimuli remains a significant clinical problem. Although numerous measures have been evaluated, instruments that are valid, reliable, and clinically feasible are not yet available. The purpose of this paper is to critique the studies that have been done using biochemical, physiological, and behavioral measures to evaluate neonatal responses to painful stimuli. Specific issues regarding measurement in premature and critically ill neonates are emphasized. The intent of this review and critique of the literature is to stimulate additional research into the assessment of neonatal pain.

[Glucose metabolism in children undergoing extracorporeal circulation: its correlation with weight and the degree of hypothermia]

INTRODUCTION

A prospective study has been carried out in 33 children with congenital heart disease, aged 5 days to 16 years, operated on with the aid of cardiopulmonary bypass (CPB), in order to evaluate intra and postoperative glycemia in relation to children's weight and intra-CPB perfusion temperature.

MATERIAL AND METHODS

Plasmatic levels of glucose, lactate, insulin, C-peptide, growth hormone (GH) and cortisol were measured at five different times, from pre-CPB up to 18 hours post-CPB. Thirteen children weighing less than 10 kilograms (group I) were compared to 20 children weighing more than 10 kilograms (group II), and 15 children operated on with perfusion temperature below 27 degrees C (group A) were compared to 18 with perfusion temperature above 27 degrees C.

RESULTS

All the cases showed intraoperative hyperglycemia. In relation to weight, evolution of glycemia was similar in both groups but anaerobic glycolysis was significantly higher in group I. In relation to temperature, glycemia, lactic acidemia intra- and post-CPB and serum C-peptide post-CPB were significantly higher in group A. Intraoperative insulin was decreased and GH serum levels were also higher in group I and A, but fell drastically post-CPB in all groups.

CONCLUSIONS

Perioperative control of glycemia is important in children operated on with the aid of CPB. Control of lactic acidemia is also expedient. Carbohydrates metabolism and its hormonal regulation are more disturbed in infants and in children operated on with low perfusion temperature.

Does change in skin perfusion provide a good index to monitor the sympathetic response to a noxious stimulus in preterm newborns?

Skin perfusion was measured using laser Doppler fluximetry (LDF) in 16 preterm babies undergoing a standardised heel prick procedure. Although there was a significant reduction in skin blood flow following the heel prick, this was variable and dependent on basal skin blood flow. This, together with loss of data due to movement artefact, makes this technique unreliable in quantifying the sympathetic response to a noxious stimulus in preterm infants.

Serum lactate as a predictor of mortality after paediatric cardiac surgery

OBJECTIVE

To assess the value of sequential lactate measurement in predicting postoperative mortality after surgery for complex congenital heart disease in children.

DESIGN

Prospective observational study.

SETTING

Sixteen bedded paediatric intensive care unit (PICU).

SUBJECTS

Ninety nine children (90 survivors, nine non-survivors).

MEASUREMENTS

Serum lactate and base deficit were measured on admission and every six hours thereafter. Data were analysed by Mann-Whitney and Fisher's exact tests.

RESULTS

There was considerable overlap in initial lactate values between the survivor and non-survivor groups. Initial lactate was significantly raised in non-survivors (median 8.7, range 1.9-17.6 mmol/l) compared with survivors (median 2.4, range 0.6-13.6 mmol/l) (p = 0.0002). Twenty one patients (21.1%) with initial lactate concentrations greater than 4.5 mmol/l survived to PICU discharge. Using receiver operating characteristic analysis an initial lactate of 6 mmol/l had the optimum predictive value for mortality. Initial postoperative serum lactate > 6 mmol/l predicted mortality with sensitivity 78%, specificity 83%, and positive predictive value of only 32%.

CONCLUSION

Initial lactate concentrations have poor positive predictive value for mortality. The routine measurement of lactate for this purpose cannot be justified in clinical practice.

Serum lactates correlate with mortality after operations for complex congenital heart disease

BACKGROUND

The objective of this study was to determine whether serum lactate levels predict mortality in children less than 1 year of age who have undergone cardiopulmonary bypass and operations for complex congenital heart disease.

METHODS

The initial lactate, maximum lactate, and lactate levels at 4 to 6 hours after operation were analyzed for each of 48 children less than 12 months of age who underwent cardiopulmonary bypass.

RESULTS

Data were analyzed for the 6 patients who died and the 42 patients who survived. For the patients who died, the initial postoperative serum lactate, maximum lactate, and 4- to 6-hour lactate levels were significantly higher than those in the patients who survived. All patients with an initial lactate less than 7 mmol/L, a maximum lactate less than 9 mmol/L, or a 4- to 6-hour lactate level less than 4 mmol/L survived to hospital discharge.

CONCLUSIONS

Serum lactate levels may be a useful predictor of mortality in children less than 1 year of age who have undergone cardiopulmonary bypass. An elevation in serum lactate level after a complex operation for congenital heart disease should be taken as a serious indicator of potential mortality.

Glucose versus lactated Ringer's solution during pediatric cardiac surgery

OBJECTIVE

Whether intraoperative fluid infusion should contain glucose during pediatric cardiac surgery remains controversial. This study was performed to compare the effects of glucose and glucose-free solutions on blood glucose and blood insulin levels during total repair of congenital heart diseases.

DESIGN

Prospective randomized and blinded study.

SETTING

Cardiovascular university center.

PARTICIPANTS

Forty nondiabetic children, weight ranging from 4 to 10 kg, scheduled for cardiac surgical procedures requiring cardiopulmonary bypass (CPB) without total circulatory arrest.

INTERVENTIONS

Group R (n = 20) was administered lactated Ringer's solution intraoperatively, and group G (n = 20) received 5% glucose. Fluids were infused at a rate of 3 mL/kg/h in the two groups from the induction of anesthesia to the end of the surgical procedure. Blood glucose and insulin were sampled before infusion (Tzero), before CPB (T1), 10 minutes after initiation of CPB (T2), 10 minutes after initiation of rewarming (T2), and at the end of the procedures (T4). Postoperatively, blood glucose was measured at the first, 12th, and 24th hours.

MEASUREMENTS AND RESULTS

During the prabypass period, three children in group R had severe hypoglycemia (blood glucose < 40 mg/dL). After initiation of CPB, blood glucose increased in both groups, with a small difference at the end of the procedure. No infants in the two groups had blood glucose higher than 239 mg/dL.

CONCLUSIONS

Glucose withdrawal during pediatric cardiac surgery induces threatening hypoglycemia during the prabypass period, and moderate intraoperative glucose administration (2.5 mg/kg/min) is not responsible for major hyperglycemia.

Post-operative pain management

For many years pediatric procedural and postoperative pain has been undertreated or not treated. In some areas this practice still exists and is a likely reflection of persistence of myths related to the infant's ability to perceive pain. Such myths include the lack of ability to perceive pain or remember painful experiences. New literature exists showing that these former beliefs do not hold true. The appropriate management of postoperative pain is contingent on a cooperative effort from pediatric surgeons, pediatric anesthesiologists, pediatricians, and parents. There are many ways to treat postoperative pain. The method of postoperative analgesia depends on the patient, underlying medical conditions, the type of surgery, the patient's disposition following surgery (inpatient vs. outpatient), and the physician's comfort level with a particular analgesic regimen. Many pediatric anesthesiologists and surgeons have excellent success with the utilization of regional anesthetic techniques as treatment for postoperative pain. Caudal epidural blocks, ilioinguinal/iliohypogastric nerve blocks, and penile nerve blocks are some of the commonly used blocks. These blocks not only provide excellent postoperative analgesia, but are great adjuncts to general anesthesia, thus, reducing the amount of general anesthesia required. Additionally, the use of epidural opioids is extremely useful in patients following major abdominal, thoracic, and orthopedic surgery. Traditional medications such as oral and parenteral narcotics, non-steroidal anti-inflammatory drugs, and acetaminophen (paracetamol), are much more commonly used to treat postoperative pain. Regardless of the analgesic regimen chosen, we must assure our pediatric patients the least painful perioperative experience possible.

Pain and ideology in human and veterinary medicine

Historically, physicians and veterinarians have placed much less emphasis on felt pain than ordinary citizens do. This is, in part, a function of the philosophical and valuational presuppositions accompanying the development of modern reductionistic Newtonian Science. In the 20th century, these presuppositions were hardened into an ideology affirming that science (and medicine) could not deal with the subjective experience or make value judgments, including ethical judgments. Control of felt pain, and the moral imperative favoring such control, were both bracketed by this ideology. With recent major changes in social ethics, however, and with recent realizations that pain is biologically active, both human and veterinary medicine can no longer ignore the moral and medical dimensions of felt pain.

Combined spinal and epidural anaesthesia for major abdominal surgery in infants

PURPOSE

Subarachnoid anaesthesia is becoming increasingly popular in neonates and infants. However, single dose spinal anaesthesia is of limited value for major abdominal surgery in infants due to its short duration of action and inability to provide analgesia in the post operative period. A new technique of combined spinal and epidural anaesthesia for major abdominal surgery in the infant is described.

METHODS

Data were gathered prospectively from 19 infants presenting for upper and lower abdominal surgery. Anaesthesia was induced with a subarachnoid injection of tetracaine. After the subarachnoid block was established, an epidural catheter was placed for further intraoperative and postoperative management. Data collected included age and weight of the patients, type and duration of the surgical procedure. Doses of local anaesthetics as well as the need for intraoperative and postoperative supplements were recorded. An illustrative case report is provided.

RESULTS

Infants studied represented a wide range of weights (1520-7840 g). Spinal anaesthesia was successful in all 19 patients. A variety of extensive surgical procedures including small bowel resections and various genitourinary procedures were successfully performed. In 17 patients a functioning epidural catheter was in place postoperatively. In these patients effective analgesia was maintained with dilute solutions of epidural bupivacaine. Only three doses of narcotic were required for pain control. No patient required postoperative mechanical ventilation or tracheal intubation.

CONCLUSION

Combined spinal and epidural anaesthesia is a potential option to general anaesthesia for major abdominal surgery in infants.

Through a glass darkly: using behavior to assess pain

Behavior assessment is crucial to the process of evaluation of pain and discomfort in veterinary patients. Behavioral responses to pain and other stressors are a function of the interaction between the individual and its environment, and are influenced by many factors including species, breed, age, sex, source of pain, and coexisting disease. Behavioral changes associated with acute postoperative pain typically peak within 24 hours and wane progressively thereafter. The intensity and duration of postoperative pain correlate with the location and extent of tissue injury, but there is much inter-patient variation of each characteristic. Published methods of systematic evaluation of pain in animals include objective measures of physiologic responses to experimental pain, subjective or semi-objective assessment of postoperative behavior, and quantitative measures of postoperative behavior and physiology. The techniques of quantitative measures of behavior are similar to pain-rating instruments developed for use in young children. Although objective assessment tools are difficult to develop and time consuming to apply, their methodological rigor and objectivity allow evaluation of behavior with minimal observer bias. Until objective assessment tools become widely used clinically, the best approach is to actively seek out evidence of pain in our patients, assuming its presence whenever there is tissue injury or inflammation.

Patterns of recovery in the Guillain-Barre syndromes

Clinical, electrodiagnostic, and pathologic studies indicate that the Guillain-Barre syndromes (GBSs) include both primary demyelinating and primary axonal forms. The axonal forms are usually thought to have a poorer prognosis, with less chance for rapid or complete recovery. In northern China, epidemics of one axonal form, acute motor axonal neuropathy (AMAN), occur annually in the summer. Autopsy studies in some fatal cases have demonstrated wallerian-like degeneration of motor roots and motor fibers in the peripheral nerves. Recovery of such patients would require axonal regeneration along the entire length of the nerve fiber. In a 2-year prospective study of GBS at a single hospital in northern China, 42 patients were classified as having either AMAN (32 patients), acute inflammatory demyelinating polyneuropathy (AIDP) (8 patients), or as undetermined (2 patients) by electrodiagnostic criteria. Their recoveries were monitored clinically. The recovery times of AMAN and AIDP patients were similar: the median time to regain the ability to walk 5 meters with assistance was 31 days for patients classified as having AMAN and 32 days for those classified as having AIDP. These rapid recovery times are incompatible with severe wallerian degeneration of the ventral roots and motor nerve fibers. The rapid recoveries observed in AMAN patients could be explained by relatively quickly reversible immune-mediated changes at nodes of Ranvier in motor fibers, by degeneration and regeneration of intramuscular motor nerve terminals, or both.

Overdoses of pethidine given to two preterm neonates

This paper reports two mechanically ventilated preterm babies who received overdoses of pethidine in the neonatal period. One of the neonates (gestational age 26 weeks, birthweight 1040 g) received repeated appropriate doses, which resulted in central nervous system irritability and convulsion due to accumulation of the drug and its metabolite, norpethidine. The other neonate (gestational age 27 weeks, birthweight 980 g) received a major (10-fold) overdose with little clinical effect. These two cases indicate notable individual variability in the responses of babies to pethidine. This is typical of other opioids, too. Therefore, the dosing of opioids to neonates should be titrated individually, and the patients should be observed carefully.

Treatment of inclusion-body myositis with IVIg: a double-blind, placebo-controlled study

We randomized 19 patients with inclusion-body myositis (IBM) to a double-blind, placebo-controlled, crossover study using monthly infusions of 2 g/kg intravenous immunoglobulin (IVIg) or placebo for 3 months. Patients crossed over to the alternate treatment after a washout period. We evaluated responses at baseline and at the end of each treatment period using expanded (0-10) MRC scales, the Maximum Voluntary Isometric Contraction (MVIC) method, symptom and disability scores, and quantitative swallowing studies. We calculated the differences in scores between IVIg and placebo from baseline to end of treatment. Of the 19 patients, 9 (mean age, 61.2 years; mean disease duration, 5.6 years) were randomized to IVIg and 10 (mean age, 66.1 years; mean disease duration, 7.4 years) to placebo. During IVIg the patients gained a mean of 4.2 (-16 to +39.8) MRC points, and during placebo lost 2.7 (-10 to +8) points (p < 0.1). These gains were not significant. Similar results were obtained with the MRC and MVIC scores when the patients crossed to the alternate treatment. Six patients had a functionally important improvement by more than 10 MRC points that declined when crossed over to placebo. Limb-by-limb analysis demonstrated that during IVIg the muscle strength in 39% of the lower extremity limbs significantly increased compared with placebo (p < 0.05), while a simultaneous decrease in 28% of other limbs was detected. The clinical importance of these minor gains is unclear. The duration of swallowing functions measured in seconds with ultrasound improved statistically in the IVIg-randomized patients (p < 0.05) compared with placebo. Although the study did not establish efficacy of IVIg, possibly because of the small sample size, the drug induced functionally important improvement in 6 (28%) of the 19 patients. Whether the modest gains noted in certain muscle groups justify the high cost of trying IVIg in IBM patients at a given stage of the disease remains unclear.

Intrathecal morphine for coronary artery bypass grafting and early extubation

Aggressive control of pain during the immediate postoperative period after cardiac surgery with early tracheal extubation may decrease morbidity and mortality. This prospective, randomized, double-blinded, placebo-controlled clinical study examined the use of intrathecal morphine in patients undergoing cardiac surgery and its influence on early tracheal extubation and postoperative analgesic requirements. Patients were randomized to receive either 10 micrograms/kg of intrathecal morphine (n = 19) or intrathecal placebo (n = 21). Perioperative anesthetic management was standardized (intravenous (IV) fentanyl, 20 micrograms/kg, and IV midazolam, 10 mg) and included postoperative patient-controlled morphine analgesia. Of the patients who were tracheally extubated during the immediate postoperative period, the mean time from intensive care unit arrival to extubation was significantly prolonged in patients who received intrathecal morphine (10.9 h) when compared to patients who received intrathecal placebo (7.6 h). Three patients who received intrathecal morphine had extubation substantially delayed because of prolonged ventilatory depression. Although mean postoperative IV morphine use for 48 h was less in patients who received intrathecal morphine (42.8 mg) when compared to patients who received intrathecal placebo (55.0 mg), the difference between groups was not statistically significant. In conclusion, intrathecal morphine offers promise as a useful adjunct in controlling postoperative pain in patients after cardiac surgery. However, the optimal dose of intrathecal morphine in this setting, along with the optimal intraoperative baseline anesthetic that will provide significant analgesia, yet not delay extubation in the immediate postoperative period, remains to be elucidated.

Plasma neuropeptide Y and catecholamines in pediatric patients undergoing cardiac operations

OBJECTIVE

Our objective was to assess the sympathoadrenal response in pediatric patients undergoing repair of congenital cardiac defects.

METHODS

Plasma catecholamine (norepinephrine and epinephrine) and neuropeptide Y concentrations were quantified before and after cardiopulmonary bypass to assess the response to cardiopulmonary bypass. To determine the response to aortic occlusion, levels of plasma catecholamines and neuropeptide Y were measured at the time of and immediately after release of the aortic crossclamp.

RESULTS

During cardiopulmonary bypass, no significant change in levels of plasma norepinephrine (n = 43), epinephrine (n = 37), or neuropeptide Y (n = 46) was observed. Aortic occlusion induced a significant increase in plasma neuropeptide Y, but not in catecholamines. There was a greater increase in plasma neuropeptide Y in children older than age 1 year than in those younger than 1 year.

CONCLUSIONS

Plasma neuropeptide Y may be a useful marker of sympathetic nervous system activity. Children younger than age 1 year showed a lesser sympathetic response compared with the response in older children.

Simultaneous measurement of the rates of appearance of palmitic and linoleic acid in critically ill infants

Lipolysis has been measured in humans by means of stable isotope techniques using labeled palmitic acid (PA) or glycerol as tracers. If other fatty acids (FA) such as linoleic acid (LLA) have the same rate of appearance (Ra) as PA and therefore contribute equally to oxidative and nonoxidative metabolism is unknown. We infused albumin-bound [U-13C]PA and [U-13C]LLA in seven critically ill infants (weight 3.6 +/- 1.3 kg, age 57 +/- 64 d) receiving 20.9 +/- 5.4 kcal. kg-1.d-1 of i.v. glucose only, and measured simultaneously the Ra of PA and LLA from the isotopic enrichment of plasma FFA by mass spectrometry. A needle biopsy of the s.c. adipose tissue was obtained for FA composition. PA in adipose tissue was higher than LLA (40 +/- 6.7 versus 5.4 +/- 3.2 mol %, p < 0.001). The Ra values of PA and LLA were 5.73 +/- 2.79 and 1.34 +/- 0.92 mumol.kg-1.min-1, respectively (p = 0.005). However, the ratio of the FA's Ra to their respective mol% values in adipose tissue was lower for PA than for LLA (0.15 +/- 0.06 versus 0.25 +/- 0.06, p = 0.02). The Ra of LLA acid was higher than could be expected from the FA composition of adipose tissue, thus indicating a preferential release of LLA during lipolysis. In critically ill infants receiving only i.v. glucose, the contribution of LLA to the oxidative and nonoxidative metabolism may be larger than what assumed from the FA composition of plasma and adipose tissue.

The effect of detomidine and its antagonism with tolazoline on stress-related hormones, metabolites, physiologic responses, and behavior in awake ponies

Six ponies were used to investigate the effect of tolazoline antagonism of detomidine on physiological responses, behavior, epinephrine, norepinephrine, cortisol, glucose, and free fatty acids in awake ponies. Each pony had a catheter inserted into a jugular vein 1 hour before beginning the study. Awake ponies were administered detomidine (0.04 mg/kg intravenously [i.v.]) followed 20 minutes later by either tolazoline (4.0 mg/kg i.v.) or saline. Blood samples were drawn from the catheter 5 minutes before detomidine administration (baseline), 5 minutes after detomidine administration, 20 minutes before detomidine administration which was immediately before the administration of tolazoline or saline (time [T] = 0), and at 5, 30, and 60 minutes after injections of tolazoline or saline (T = 5, 30, and 60 minutes, respectively). Compared with heart rate at T = 0, tolazoline antagonism increased heart rate 45% at 5 minutes. There was no difference in heart rate between treatments at 30 minutes. Blood pressure remained stable after tolazoline, while it decreased over time after saline. Compared with concentrations at T = 0, tolazoline antagonism of detomidine in awake ponies resulted in a 55% increase in cortisol at 30 minutes and a 52% increase in glucose at 5 minutes. The change in free fatty acids was different for tolazoline and saline over time. Free fatty acids decreased after detomidine administration. Free fatty acids did not change after saline administration. After tolazoline administration, free fatty acids increased transiently. Tolazoline tended to decrease sedation and analgesia at 15 and 60 minutes postantagonism. Antagonism of detomidine-induced physiological and behavioral effects with tolazoline in awake ponies that were not experiencing pain appears to precipitate a stress response as measured by cortisol, glucose, and free fatty acids. If antagonism of an alpha-agonist is contemplated, the potential effect on hormones and metabolites should be considered.

Pain management in newborns: how far have we progressed in research and practice?

Compelling research supports the newborn infant's capacity for pain. Yet, pain is frequently underestimated and undertreated. This is a result of limited understanding of pain pathway development, immediate and long-term consequences, measurement tools and approaches, and safety and efficacy of pain-relieving interventions. This paper reviews recent research in relation to management of pain in the newborn, and presents implications for practice and future research.

Comparison of continuous infusion of fentanyl to bolus dosing in neonates after surgery

OBJECTIVE

Concern about respiratory depression may lead to underuse of postoperative narcotic analgesia in neonates. The authors compared continuous infusion of fentanyl with bolus dosing in infants after surgery to determine whether continuous infusion is associated with less respiratory depression.

STUDY DESIGN

In the first phase of the study, 16 patients were randomly assigned to receive fentanyl by continuous infusion (C) or bolus dosing every 2 hours (B) in a double-blinded trial. Respiratory events were recorded. An observational pain score and saliva for cortisol concentration were obtained 2, 8, and 24 hours after beginning treatment to compare efficacy of pain control. In the second phase, 20 additional patients received fentanyl by continuous infusion in an unblinded fashion, with the same data collection, to more accurately determine the incidence of respiratory events.

RESULTS

In phase 1, apnea occurred in eight of nine B patients (89%) compared with one of seven C patients (14%; P < .009), prompting termination of the randomized trial. The incidence of apnea or significant respiratory depression in the next 20 patients (phase 2) who received fentanyl by continuous infusion was 25% (5 of 20; P < .01 v B). Episodes of apnea in B patients required significantly more intervention than episodes in C patients (P < .01). However, in phase 2, more patients remained intubated and ventilated than in phase 1. Pain scores and salivary cortisol concentrations decreased over the 24-hour study period and were similar in B and C patients during both phases of the study.

CONCLUSION

Continuous infusion of fentanyl at the doses studied is associated with pain control similar to that with bolus dosing at regular intervals. Although episodes of respiratory depression were less severe and less frequent for C patients, there may be an increased need for ventilator support with continuous infusion of fentanyl to achieve acceptable pain control. Providing adequate pain control to neonates in the immediate postoperative period remains a challenge.

Prevalence and source of pain in pediatric inpatients

Our knowledge of the prevalence and sources of pain within hospital is limited. The present study is an epidemiological investigation of pain in a pediatric hospital. All children who were inpatients in a tertiary care hospital (excluding Neonatal ICU and psychiatry patients) and one parent per child were potential subjects. Interviews were conducted on three weekdays. Parent interviews were used for children less than 5 years of age (n = 102); child interviews were used for children age 5 years and older (n = 98). Subjects reported the intensity and source of the worst, usual and current pain during the past 24 h, and help received for pain. Medical and demographic variables and analgesics prescribed and administered were obtained from the medical record. Forty-nine percent of subjects reported clinically significant levels of worst pain. Twenty-one percent of subjects had clinically significant levels of usual pain. Causes of pain were variable and included disease, surgery, and intravenous lines (I.V.). Pain intensity was not significantly related to age, gender, patient type (medical, surgical), or diagnostic category. Children were given significantly less medication than was prescribed, regardless of their reported pain level. Nurses, mothers, and 'no-one' were frequently reported as helping with pain. Medications and nonpharmacological methods were reported as helpful in managing pain. Many children endure unacceptable levels of pain during hospitalization. Pain prevention and management must be more aggressive. Pain assessment should be approached with the same attention as vital signs. Improvements in analgesic prescription and administration practices and non-pharmacological pain control methods are needed.

A controlled trial of amino acid therapy in amyotrophic lateral sclerosis: I. Clinical, functional, and maximum isometric torque data

We conducted a two center, double-blind, placebo-controlled treatment trial with oral branched chain amino acids (BCAA) (L-leucine 12 g, L-isoleucine 8 g, and L-valine 6.4 g daily) or L-threonine (4 g daily) with pyridoxal phosphate (160 mg daily) for six months in patients with amyotrophic lateral sclerosis (ALS). The effect of treatment on disease progression was estimated every two months by recording clinical muscle strength, maximum isometric muscle torque in selected muscles, forced vital capacity (FVC), activities of daily living pertaining to the upper and lower limbs, and timed tasks. Ninety-five patients were randomized to receive BCAA (n = 31), L-threonine (n = 32), or placebo (n = 32), of whom 77 (81%) completed the trial. Mean weight loss in the placebo group was 1.1 kg and in the L-threonine group was 3.2 kg; the BCAA group gained 0.2 kg (p = 0.04). The estimated decline in FVC was about 2.5 times greater in the BCAA and L-threonine groups as compared to placebo (p = 0.03). Otherwise, no significant differences were found in the changes observed in clinical, functional, timed, or maximum torque measures among treatment groups. The amino acids were well tolerated. The results of our study failed to show a beneficial effect of BCAA or L-threonine treatment for six months on the disease course in ALS. The higher rate of loss of pulmonary function in patients treated with BCAA or L-threonine may have been due to chance, but an adverse effect of these amino acids cannot be ruled out.

Selective staining of the cerebellar molecular layer by serum IgG in Miller-Fisher and related syndromes

During 1 year, we used immunocytochemical staining of human cerebellum to screen 1,488 serums for IgG autoantibodies to Hu and Yo antigens. Three serums had none of the classically described patterns of IgG binding but instead, selectively stained the cerebellar molecular layer. Evaluation of clinical data showed that the patients had either typical Miller Fisher syndrome (MFS) or Guillain-Barré syndrome with ophthalmoplegia. Further analysis by ELISA, assay showed that all three serums had high titers of IgG anti-GQ1b autoantibodies. IgG autoantibody staining of human cerebellum, which is used for the diagnosis of paraneoplastic disorders, may have additional specificity for other, presumably autoimmune, syndromes such as MFS. The specificity of the serum IgG autoantibody binding to the cerebella molecular layer may be related to the ataxia that often occurs in these patients.

Cytomegalovirus infection and Guillain-Barré syndrome: the clinical, electrophysiologic, and prognostic features. Dutch Guillain-Barré Study Group

Guillain-Barré syndrome (GBS) is usually preceded by infections, in particular cytomegalovirus (CMV) and Campylobacter jejuni infection. We studied the clinical and electrophysiologic features of 20 CMV-associated GBS patients and compared the findings with earlier established data of C. jejuni-related GBS patients (n = 43) and of GBS patients without these infections (n = 71). The patients all participated in the Dutch GBS trial in which we compared the effect of intravenous immune globulins and plasma exchange. We demonstrate that CMV-related GBS patients have a different clinical pattern in comparison with the other two GBS groups. They are significantly younger, initially have a severe course indicated by a high frequency of respiratory insufficiency, and often develop cranial nerve involvement and severe sensory loss. This is in contrast to C. jejuni infection, which is associated with motor GBS. Both infections are associated with delayed recovery compared with the GBS patients without these infections.