Endoscopic Versus Open Repair for Craniosynostosis in Infants Using Propensity Score Matching to Compare Outcomes: A Multicenter Study from the Pediatric Craniofacial Collaborative Group

BACKGROUND

The North American Pediatric Craniofacial Collaborative Group (PCCG) established the Pediatric Craniofacial Surgery Perioperative Registry to evaluate outcomes in infants and children undergoing craniosynostosis repair. The goal of this multicenter study was to utilize this registry to assess differences in blood utilization, intensive care unit (ICU) utilization, duration of hospitalization, and perioperative complications between endoscopic-assisted (ESC) and open repair in infants with craniosynostosis. We hypothesized that advantages of ESC from single-center studies would be validated based on combined data from a large multicenter registry.

METHODS

Thirty-one institutions contributed data from June 2012 to September 2015. We analyzed 1382 infants younger than 12 months undergoing open (anterior and/or posterior cranial vault reconstruction, modified-Pi procedure, or strip craniectomy) or endoscopic craniectomy. The primary outcomes included transfusion data, ICU utilization, hospital length of stay, and perioperative complications; secondary outcomes included anesthesia and surgical duration. Comparison of unmatched groups (ESC: N = 311, open repair: N = 1071) and propensity score 2:1 matched groups (ESC: N = 311, open repair: N = 622) were performed by conditional logistic regression analysis.

RESULTS

Imbalances in baseline age and weight are inherent due to surgical selection criteria for ESC. Quality of propensity score matching in balancing age and weight between ESC and open groups was assessed by quintiles of the propensity scores. Analysis of matched groups confirmed significantly reduced utilization of blood (26% vs 81%, P < .001) and coagulation (3% vs 16%, P < .001) products in the ESC group compared to the open group. Median blood donor exposure (0 vs 1), anesthesia (168 vs 248 minutes) and surgical duration (70 vs 130 minutes), days in ICU (0 vs 2), and hospital length of stay (2 vs 4) were all significantly lower in the ESC group (all P < .001). Median volume of red blood cell administered was significantly lower in ESC (19.6 vs 26.9 mL/kg, P = .035), with a difference of approximately 7 mL/kg less for the ESC (95% confidence interval for the difference, 3-12 mL/kg), whereas the median volume of coagulation products was not significantly different between the 2 groups (21.2 vs 24.6 mL/kg, P = .73). Incidence of complications including hypotension requiring treatment with vasoactive agents (3% vs 4%), venous air embolism (1%), and hypothermia, defined as <35°C (22% vs 26%), was similar between the 2 groups, whereas postoperative intubation was significantly higher in the open group (2% vs 10%, P < .001).

CONCLUSIONS

This multicenter study of ESC versus open craniosynostosis repair represents the largest comparison to date. It demonstrates striking advantages of ESC for young infants that may result in improved clinical outcomes, as well as increased safety.

Ultrasound-guided rectus sheath block or wound infiltration in children: a randomized blinded study of analgesia and bupivacaine absorption

BACKGROUND

Rectus sheath block can provide analgesia following umbilical hernia repair. However, conflicting reports on its analgesic effectiveness exist. No study has investigated plasma local anesthetic concentration following ultrasound-guided rectus sheath block (USGRSB) in children.

OBJECTIVES

Compare the effectiveness and bupivacaine absorption following USGRSB or wound infiltration (WI) for umbilical hernia repair in children.

METHODS

A randomized blinded study comparing WI with USGRSB in 40 children undergoing umbilical hernia repair was performed. Group WI (n = 20) received wound infiltration 1 mg·kg(-1) 0.25% bupivacaine. Group RS (n = 20) received USGRSB 0.5 mg·kg(-1) 0.25% bupivacaine per side in the posterior rectus sheath compartment. Pain scores and rescue analgesia were recorded. Blood samples were drawn at 0, 10, 20, 30, 45, and 60 min.

RESULTS

Patients in the WI group had a twofold increased risk of requiring morphine (hazard ratio 2.06, 95% CI 1.01, 4.20, P = 0.05). When required, median time to first morphine dose was longer in the USGRSB group (65.5 min vs. 47.5 min, P = 0.049). Peak plasma bupivacaine concentration was higher following USGRSB than WI (median: 631.9 ng·ml(-1) IQR: 553.9-784.1 vs. 389.7 ng·ml(-1) IQR: 250.5-502.7, P = 0.002). Tmax was longer in the USGRSB group (median 45 min IQR: 30-60 vs. 20 min IQR: 20-45, P = 0.006).

CONCLUSIONS

USGRSB provides more effective analgesia than WI for umbilical hernia repair. USGRSB with 1 mg·kg(-1) 0.25% bupivacaine is associated with safe plasma bupivacaine concentration that peaks higher and later than WI. Caution against using larger volumes of higher concentration local anesthetic for USGRSB is advised.

Duration of exposure to cranial vault surgery: associations with neurodevelopment among children with single-suture craniosynostosis

OBJECTIVE

To evaluate associations between neurodevelopment and exposure to surgery and anesthetic agents in children with single-suture craniosynostosis (SSC).

BACKGROUND

Young children with SSC have unexplained neurodevelopmental delays. The possible contributions of factors related to cranial vault surgery - including anesthesia - have not been previously examined.

METHODS/MATERIALS

Two anesthesiologists reviewed the surgical records of 89 infants (70 had complete data). Primary exposures were duration of surgery and anesthesia and total duration of inhaled anesthesia (at age 6 months on average). Outcomes were the cognitive and motor scores from the Bayley Scales of Infant Development-II and language scores from the Preschool Language Scale, 3rd edition, given at age 36 months. Linear regression using robust standard error estimates was performed, adjusting for age at surgery and suture site.

RESULTS

Anesthesia duration ranged from 155 to 547 min. For every 30-min increase in anesthesia duration, the estimated average decrease in developmental test scores ranged from 1.1 to 2.9 (P ranged from <0.001 to 0.30). Similar, but weaker findings were observed with surgery duration and total duration of inhaled anesthesia. Inverse relations between exposure amounts and neurodevelopment were stronger in children with nonsagittal synostosis.

CONCLUSIONS

Average neurodevelopmental scores were lower among children experiencing longer surgeries and higher exposures to inhaled anesthesia. These associations may be due to anesthesia exposure, nonspecific effects of surgery, or unmeasured variables that correlate with surgery duration. Further study of potential causal mechanisms is warranted.

A survey of perioperative management of sickle cell disease in North America

BACKGROUND

Children with sickle cell disease frequently undergo surgical procedures that are associated with acute exacerbations of the disease. Current perioperative management practices are unclear.

OBJECTIVES

We aimed at describing the current management.

METHODS

We conducted an electronic survey of North American members of the Society for Pediatric Anesthesia, in which we asked about their perioperative management of sickle cell disease.

RESULTS

The response rate to valid addresses was 25% (n=510/2006). In four scenarios, (a patient with mild disease undergoing a minor procedure; a patient with mild disease undergoing a more invasive procedure; a patient with severe disease undergoing a minor procedure; and a patient with severe disease undergoing a more invasive procedure) 80%, 38%, 27%, and 16% of respondents, respectively, would rely on oral fluids to hydrate patients during the preoperative fast, while 13%, 34%, 44%, and 59%, respectively, would use intravenous fluid. For the same four scenarios, 64%, 28%, 33%, and 10%, respectively, would not transfuse patients in an attempt to prevent sickle cell exacerbations, while 17%, 49%, 36%, and 51%, respectively, would transfuse to a hemoglobin concentration of 10 g·dl(-1). The tendencies to administer preoperative intravenous fluid and to transfuse blood increased with disease severity and procedure invasiveness (P<0.001). Although 89% felt comfortable managing patients with sickle cell disease, 73% thought an advisory statement on optimal perioperative management was needed.

CONCLUSIONS

There is a wide variation in the management of children with sickle cell disease. Clinicians differentiate management based on disease severity and procedure type.

Anesthesia-Related Cardiac Arrest in Children: Update from the Pediatric Perioperative Cardiac Arrest Registry

BACKGROUND

The initial findings from the Pediatric Perioperative Cardiac Arrest (POCA) Registry (1994-1997) revealed that medication-related causes, often cardiovascular depression from halothane, were the most common. Changes in pediatric anesthesia practice may have altered the causes of cardiac arrest in anesthetized children.

METHODS

Nearly 80 North American institutions that provide anesthesia for children voluntarily enrolled in the Pediatric Perioperative Cardiac Arrest Registry. A standardized data form for each perioperative cardiac arrest in children </=18 yr of age was submitted anonymously. We analyzed causes of anesthesia-related cardiac arrests and related factors in 1998-2004.

RESULTS

From 1998 to 2004, 193 arrests (49%) were related to anesthesia. Medication-related arrests accounted for 18% of all arrests, compared with 37% from 1994 to 1997 (P < 0.05). Cardiovascular causes of cardiac arrest were the most common (41% of all arrests), with hypovolemia from blood loss and hyperkalemia from transfusion of stored blood the most common identifiable cardiovascular causes. Among respiratory causes of arrest (27%), airway obstruction from laryngospasm was the most common cause. Vascular injury incurred during placement of central venous catheters was the most common equipment-related cause of arrest. The cause of arrest varied by phase of anesthesia care (P < 0.01). Cardiovascular and respiratory causes occurred most commonly in the surgical and postsurgical phases, respectively.

CONCLUSIONS

A reduction in the proportion of arrests related to cardiovascular depression due to halothane may be related to the declining use of halothane in pediatric anesthetic practice. The incidence of the most common remaining causes of arrest in each category may be reduced through preventive measures.

Physical therapy alone compared with core decompression and physical therapy for femoral head osteonecrosis in sickle cell disease. Results of a multicenter study at a mean of three years after treatment

BACKGROUND

Osteonecrosis of the femoral head is a common complication in patients with sickle cell disease, and collapse of the femoral head occurs in 90% of patients within five years after the diagnosis of the osteonecrosis. However, the efficacy of hip core decompression to prevent the progression of osteonecrosis in these patients is still controversial.

METHODS

In a prospective multicenter study, we evaluated the safety of hip core decompression and compared the results of decompression and physical therapy with those of physical therapy alone for the treatment of osteonecrosis of the femoral head in patients with sickle cell disease. Forty-six patients (forty-six hips) with sickle cell disease and Steinberg Stage-I, II, or III osteonecrosis of the femoral head were randomized to one of two treatment arms: (1) hip core decompression followed by a physical therapy program or (2) a physical therapy program alone. Eight patients withdrew from the study, leaving thirty-eight who participated.

RESULTS

Seventeen patients (seventeen hips) underwent decompression combined with physical therapy, and no intraoperative or immediate postoperative complications occurred. Twenty-one patients (twenty-one hips) were treated with physical therapy alone. After a mean of three years, the hip survival rate was 82% in the group treated with decompression and physical therapy and 86% in the group treated with physical therapy alone. According to a modification of the Harris hip score, the mean clinical improvement was 18.1 points for the patients treated with hip core decompression and physical therapy compared with 15.7 points for those treated with physical therapy alone. With the numbers studied, the differences were not significant.

CONCLUSIONS

In this randomized prospective study, physical therapy alone appeared to be as effective as hip core decompression followed by physical therapy in improving hip function and postponing the need for additional surgical intervention at a mean of three years after treatment.

Unexpected cardiac arrest among children during surgery, a North American registry to elucidate the incidence and causes of anesthesia related cardiac arrest

Relatively rare adverse events, such as unexpected cardiac arrest, are difficult to study in the clinical setting. These events are often unpredictable in their occurrence (prompting interest in their investigation) and do not occur with sufficient frequency in any single institution to provide an adequate sample for analysis. A disease-specific registry is an epidemiological technique that can be used to collect data on a set of relatively rare unpredictable events. This approach was adopted for investigation of cardiac arrest in children when it became apparent from analysis of malpractice claims that a significant clinical problem existed. This report provides a brief historical account of the development of the Pediatric Peri-Operative Cardiac Arrest (POCA) Registry and elaborates on the methodology including strengths, weaknesses, and practical implementation issues.

Intussusception: hospital size and risk of surgery

OBJECTIVE

To determine whether the risk of operative management of children with intussusception varies by hospital pediatric caseload.

DESIGN

A cohort of all children with intussusception in Washington State from 1987 through 1996.

SETTING

All hospitals in Washington State.

METHODS

Five hundred seventy children with a hospital discharge diagnosis of intussusception were identified. Sixty-two were excluded because of missing data. Procedure codes for operative management and radiologic management were also identified.

RESULTS

Fifty-three percent of the children had operative reduction and 20% had resection of bowel. Children with operative reduction did not differ from those with nonoperative care by median age or gender; however, children with operative care were significantly more likely to receive care in hospitals with smaller pediatric caseloads and to have a coexisting condition associated with intussusception. Sixty-four percent of children who received care in a large children's hospital had nonoperative reduction, compared with 36% of children who received care in hospitals with 0 to 3000 annual pediatric admissions and 24% of children who had care in hospitals with 3000 to 10 000 annual pediatric admissions. Median length of stay and charges were significantly less in the large children's hospital, compared with other centers.

CONCLUSIONS

Children who received care for intussusception in a large children's hospital had decreased risk of operative care, shorter length of stay, and lower hospital charges compared with children who received care in hospitals with smaller pediatric caseloads.

Acute appendicitis risks of complications: age and Medicaid insurance

OBJECTIVES

To describe the epidemiology of acute appendicitis in children from Washington State, and to determine important risk factors for complications.

DESIGN

Retrospective cohort study.

SETTING

All children (<17 years old) treated in Washington State who were identified by hospital discharge diagnosis codes from 1987 through 1996.

METHODS

The hospital discharge data were reviewed for all children with a primary diagnosis code for acute appendicitis. Complicated disease was defined as perforation or abscess formation.

RESULTS

Young children (0-4 years old) had the lowest annual incidence of acute appendicitis, but they had a 5-fold increased risk of complicated disease (odds ratio: 4.9; 95% confidence interval: 4.0-5.9), compared with teenagers. Children with Medicaid insurance had a 1.3-fold increased risk of complicated disease, compared with children with commercial insurance (odds ratio: 1.3: 95% confidence interval: 1.2-1.4). Children with Medicaid insurance had significantly longer average length of stay (4.0+/-3.7 days) than all other payers (commercial insurance: 3.3+/-4.0 days; health maintenance organization: 3.5+/-3.1 days; and self-insured: 3.7+/-5.8 days).

CONCLUSIONS

Very young children had the greatest risk of complicated disease. Children with Medicaid insurance had increased risk of complicated disease, compared with children with commercial health insurance and longer length of stay. Additional studies are needed to evaluate barriers to care for children with Medicaid insurance.

Anesthesia-related cardiac arrest in children: initial findings of the Pediatric Perioperative Cardiac Arrest (POCA) Registry

BACKGROUND

The Pediatric Perioperative Cardiac Arrest (POCA) Registry was formed in 1994 in an attempt to determine the clinical factors and outcomes associated with cardiac arrest in anesthetized children.

METHODS

Institutions that provide anesthesia for children are voluntarily enrolled in the POCA Registry. A representative from each institution provides annual institutional demographic information and submits anonymously a standardized data form for each cardiac arrest (defined as the need for chest compressions or as death) in anesthetized children 18 yr of age or younger. Causes and factors associated with cardiac arrest are analyzed.

RESULTS

In the first 4 yr of the POCA Registry, 63 institutions enrolled and submitted 289 cases of cardiac arrest. Of these, 150 arrests were judged to be related to anesthesia. Cardiac arrest related to anesthesia had an incidence of 1.4 +/- 0.45 (mean +/- SD) per 10,000 instances of anesthesia and a mortality rate of 26%. Medication-related (37%) and cardiovascular (32%) causes of cardiac arrest were most common, together accounting for 69% of all arrests. Cardiovascular depression from halothane, alone or in combination with other drugs, was responsible for two thirds of all medication-related arrests. Thirty-three percent of the patients were American Society of Anesthesiologists physical status 1-2; in this group, 64% of arrests were medication-related, compared with 23% in American Society of Anesthesiologists physical status 3-5 patients (P < 0.01). Infants younger than 1 yr of age accounted for 55% of all anesthesia-related arrests. Multivariate analysis demonstrated two predictors of mortality: American Society of Anesthesiologists physical status 3-5 (odds ratio, 12.99; 95% confidence interval, 2.9-57.7), and emergency status (odds ratio, 3. 88; 95% confidence interval, 1.6-9.6).

CONCLUSIONS

Anesthesia-related cardiac arrest occurred most often in patients younger than 1 yr of age and in patients with severe underlying disease. Patients in the latter group, as well as patients having emergency surgery, were most likely to have a fatal outcome. The identification of medication-related problems as the most frequent cause of anesthesia-related cardiac arrest has important implications for preventive strategies.

Multi-institutional survey of graduates of pediatric anesthesia fellowship: assessment of training and current professional activities

We surveyed all the graduates of four fellowship programs in pediatric anesthesia between 1985 and 1993 to assess their current professional activities, their evaluation of fellowship training, and their opinions on future directions of such training. One-hundred ninety-one (62%) of the graduates responded. Nearly all of the respondents had sought fellowship training for pediatric anesthesia and thought that the training was worthwhile. At the time of the survey, 40% worked in a children's hospital, 72% had university or affiliate positions, and 54% had a practice that was > 50% pediatric. Those with > or = 12 mo fellowship and/or board certification in pediatrics were the most likely to have a pediatric-dedicated practice. Seventy percent of the respondents thought that fellowship training should be for 12 mo, and the proportion of respondents who recommended inclusion of training in pain management and clinical research was greater than the number who had actually received such training. Fifty-eight percent of respondents supported restriction of fellowship positions in the future, but 83% did not support a mandatory 2-yr fellowship with research training. We conclude that fellowships in pediatric anesthesia seem to be successful in providing training that is not only satisfying to the trainees, but that is also followed by active involvement in the care of children and in the training of residents and fellows in anesthesia. Additional information should be gathered to assess the impact of this training on pediatric care, to formulate a standardized curriculum, and to justify support for such training in the future.

IMPLICATIONS

We surveyed graduates of four fellowship programs in pediatric anesthesia (1985-1993) to assess current professional activities, fellowship training, and future directions of such training. Fellowships in pediatric anesthesia seem to provide training that is satisfying to trainees and that is followed by active involvement in the care of children.

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.

Cholecystectomy in sickle cell anemia patients: perioperative outcome of 364 cases from the National Preoperative Transfusion Study. Preoperative Transfusion in Sickle Cell Disease Study Group

Cholecystectomy is the most common surgical procedure performed in sickle cell anemia (SCA) patients. We investigated the effects of transfusion and surgical method on perioperative outcome. A total of 364 patients underwent cholecystectomy: group 1 (randomized to aggressive transfusion) 110 patients; group 2 (randomized to conservative transfusion) 120 patients; group 3 (nonrandomized nontransfusion) 37 patients; and group 4 (nonrandomized transfusion) 97 patients. Patients were similar except group 3 patients were more likely to be female, over 20 years old, smokers, and more healthy by American Society of Anesthesiologists (ASA) physical status score. Total complication rate was 39%: sickle cell events 19%; intraoperative or recovery room events 11%; transfusion complications 10%; postoperative surgical events 4%; and death 1%. Group 3 patients had the highest incidence of sickle cell events (32%). Open cholecystectomies were performed in 58% and laparoscopic in 42%. Laparoscopic patients were younger and more healthy by ASA score. Laparoscopic patients had longer anesthesia time (3.2 v 2.9 hours), but shorter hospitalization time (6.4 days v 9.8). Complications were similar between these two groups. We conclude that SCA patients undergoing cholecystectomy have a high perioperative morbidity, and the incidence of sickle cell events may be higher in patients not preoperatively transfused. We recommend a conservative preoperative transfusion regimen, and we encourage the use of the laparoscopic technique for SCA patients undergoing elective cholecystectomy.

Morphine pharmacokinetics during continuous infusion of morphine sulfate for infants receiving extracorporeal membrane oxygenation

OBJECTIVES

To determine a) if serum morphine concentration changes during the first 3 hrs of extracorporeal membrane oxygenation (ECMO); and b) if absorption of morphine onto the membrane oxygenator is responsible for these changes. Also, morphine clearance during the first 5 days of ECMO was studied.

DESIGN

Prospective, open-label study with consecutive patient enrollment.

SETTING

Neonatal intensive care unit at a university-affiliated, children's hospital.

SUBJECTS

Eleven neonates with severe persistent pulmonary hypertension of the newborn receiving continuous intravenous infusions of morphine sulfate and requiring ECMO.

INTERVENTIONS

Blood samples were obtained from the subjects and ECMO circuits at predetermined time intervals.

MEASUREMENTS AND MAIN RESULTS

Serum morphine concentration was determined using high-performance liquid chromatography. Morphine concentrations were no different from baseline at 5 mins, 1 hr, or 3 hrs after beginning ECMO. There was no significant difference in morphine concentration from samples taken immediately proximal and distal to the membrane oxygenator at 5 mins, 1 hr, and 3 hrs after the start of ECMO. Morphine clearance was calculated on days 1, 3, and 5 of ECMO. The mean value for morphine clearance was 11.7 +/- 9.3 (SD) ml/min/kg (range 2.6 to 34.5).

CONCLUSIONS

The initiation of ECMO does not lead to a significant decrease in serum morphine concentration and there is no uptake of morphine onto the membrane oxygenator of the ECMO circuit. Morphine clearance for infants receiving ECMO is variable.

Epidural and intravenous bolus morphine for postoperative analgesia in infants

PURPOSE

To compare two doses of bolus epidural morphine with bolus iv morphine for postoperative pain after abdominal or genitourinary surgery in infants.

METHODS

Eighteen infants were randomly assigned to bolus epidural morphine (0.025 mg.kg-1 or 0.050 mg.kg-1) or bolus iv morphine (0.050-0.150 mg.kg-1). Postoperative pain was assessed and analgesia provided, using a modified infant pain scale. Monitoring included continuous ECG, pulse oximetry, impedance and nasal thermistor pneumography. The CO2 response curves and serum morphine concentrations were measured postoperatively.

RESULTS

Postoperative analgesia was provided within five minutes by all treatment methods. Epidural groups required fewer morphine doses (3.8 +/- 0.8 for low dose [LE], 3.5 +/- 0.8 for high dose epidural [HE] vs. 6.7 +/- 1.6 for iv, P < 0.05) and less total morphine (0.11 +/- 0.04 mg.kg-1 for LE, 0.16 +/- 0.04 for HE vs 0.67 +/- 0.34 for iv, P < 0.05) on POD1. Dose changes were necessary in all groups for satisfactory pain scores. Pruritus, apnoea, and haemoglobin desaturation occurred in all groups. CO2 response curve slopes, similar preoperatively (range 36-41 ml.min-1.mmHg ETCO2-1.kg-1) were generally depressed (range, 16-27 ml.min-1.mmHg ETCO2-1.kg-1) on POD1. Serum morphine concentrations, negligible in LE (< 2 ng.ml-1), were similar in the HE and iv groups (peak 8.5 +/- 12.5 and 8.6 +/- 2.4 ng.ml-1, respectively).

CONCLUSION

Epidural and iv morphine provide infants effective postoperative analgesia, although side effects are common. Epidural morphine gives satisfactory analgesia with fewer doses (less total morphine); epidural morphine 0.025 mg.kg-1 is appropriate initially. Infants receiving epidural or iv morphine analgesia postoperatively need close observation in hospital with continuous pulse oximetry.

Induction, recovery, and safety characteristics of sevoflurane in children undergoing ambulatory surgery. A comparison with halothane

BACKGROUND

Sevoflurane is an inhalational anesthetic with characteristics suited for use in children. To determine whether the induction, recovery, and safety characteristics of sevoflurane differ from those of halothane, the following open-labeled, multicenter, randomized, controlled, phase III study in children undergoing ambulatory surgery was designed.

METHODS

Three hundred seventy-five children, ASA physical status 1 or 2, were randomly assigned in a 2:1 ratio to receive either sevoflurance or halothane, both in 60% N2O and 40% O2. Anesthesia was induced using a mask with an Ayre's t piece or Bain circuit in four of the centers and a mask with a circle circuit in the fifth center. Maximum inspired concentrations during induction of anesthesia were 7% sevoflurane and 4.3% halothane. Anesthesia was maintained by spontaneous ventilation, without tracheal intubation. End-tidal concentrations of both inhalational anesthetics were adjusted to 1.0 MAC for at least 10 min before the end of surgery. Induction and recovery characteristics and all side effects were recorded. The plasma concentration of inorganic fluoride was measured at induction of and 1 h after anesthesia.

RESULTS

During induction of anesthesia, the time to loss of the eyelash reflex with sevoflurane was 0.3 min faster than with halothane (P < 0.001). The incidence of airway reflex responses was similar, albeit infrequent with both anesthetics. The total MAC.h exposure to sevoflurane was 11% less than the exposure to halothane (P < 0.013), although the end-tidal MAC multiple during the final 10 min of anesthesia was similar for both groups. Early recovery as evidenced by the time to response to commands after sevoflurane was 33% more rapid than it was after halothane (P < 0.001), although the time to discharge from hospital was similar for both anesthetics. The mean ( +/- SD) plasma concentration of inorganic fluoride 1 h after discontinuation of sevoflurane was 10.3 +/- 3.5 microM. The overall incidence of adverse events attributable to sevoflurane was similar to that of halothane, although the incidence of agitation attributable to sevoflurane was almost threefold greater than that attributable to halothane (P < 0.004).

CONCLUSIONS

Sevoflurane compared favorably with halothane. Early recovery after sevoflurane was predictably more rapid than after halothane, although this was not reflected in a more rapid discharge from the hospital. The incidence of adverse events was similar for both anesthetics. Clinically, the induction, recovery, and safety characteristics of sevoflurane and halothane are similar. Sevoflurane is a suitable alternative to halothane for use in children undergoing minor ambulatory surgery.

A comparison of conservative and aggressive transfusion regimens in the perioperative management of sickle cell disease. The Preoperative Transfusion in Sickle Cell Disease Study Group

BACKGROUND

Preoperative transfusions are frequently given to prevent perioperative morbidity in patients with sickle cell anemia. There is no consensus, however, on the best regimen of transfusions for this purpose.

METHODS

We conducted a multicenter study to compare the rates of perioperative complications among patients randomly assigned to receive either an aggressive transfusion regimen designed to decrease the hemoglobin S level to less than 30 percent (group 1) or a conservative regimen designed to increase the hemoglobin level to 10 g per deciliter (group 2).

RESULTS

Patients undergoing a total of 604 operations were randomly assigned to group 1 or group 2. The severity of the disease, compliance with the protocol, and the types of operations were similar in the two groups. The preoperative hemoglobin level was 11 g per deciliter in group 1 and 10.6 g per deciliter in group 2. The preoperative value for hemoglobin S was 31 percent in group 1 and 59 percent in group 2. The most frequent operations were cholecystectomies (232), head and neck surgery (156), and orthopedic surgery (72). With the exception of transfusion-related complications, which occurred in 14 percent of the operations in group 1 and in 7 percent of those in group 2, the frequency of serious complications was similar in the two groups (31 percent in group 1 and 35 percent in group 2). The acute chest syndrome developed in 10 percent of both groups and resulted in two deaths in group 1. A history of pulmonary disease and a higher risk associated with surgery were significant predictors of the acute chest syndrome.

CONCLUSIONS

A conservative transfusion regimen was as effective as an aggressive regimen in preventing perioperative complications in patients with sickle cell anemia, and the conservative approach resulted in only half as many transfusion-associated complications.

Postoperative apnea, bradycardia, and oxygen desaturation in formerly premature infants: prospective comparison of spinal and general anesthesia

Eighteen formerly premature infants scheduled for inguinal herniorrhaphy and who were less than 51 wk postconceptional age were assigned to either the general anesthesia group (GA: atropine, halothane, and nitrous oxide) or the spinal anesthesia group (SA: hyperbaric tetracaine). Twelve-hour, three-channel continuous recordings of respiratory rate (chest wall impedance), electrocardiogram (ECG), and hemoglobin O2 saturation (SpO2) were obtained preoperatively and after surgery. These were analyzed for short (11-15s) and long (> 15 s) apnea spells, periodic breathing, and episodes of hemoglobin oxygen desaturation and bradycardia. Infants in the GA group had lower postoperative minimum SpO2 (68.7% +/- 11.4%) and minimum heart rate (79 bpm +/- 19) than infants in the SA group (80.7% +/- 9.2%, and 109 bpm +/- 30, respectively; P < 0.05) and had lower postoperative minimum SpO2 and minimum heart rate than they had preoperatively (79.0% +/- 13.7%, and 93 bpm +/- 31, respectively; P < 0.05); pre- and postoperative studies in the SA group did not differ. There were no differences in the incidence of postoperative central apnea. We conclude that spinal anesthesia reduces postoperative hemoglobin oxygen desaturation and bradycardia in formerly premature infants undergoing inguinal herniorrhaphy.

Pain management for children following selective dorsal rhizotomy

Selective dorsal rhizotomy (SDR) is a neurosurgical procedure used for treating lower extremity spasticity in patients with cerebral palsy. The purpose of this paper is to present a review of our institution's first three years' experience with postoperative pain and spasticity management in patients who have undergone SDR. The medical records of the 55 patients who had an SDR during the study period were reviewed. The basis of postoperative analgesia was morphine, with the majority of patients receiving continuous morphine infusions (20-40 micrograms.kg-1.hr-1 (n = 49), 60 micrograms.kg-1.hr-1 (n = 1)). Four patients used a patient-controlled delivery system. One patient had successful analgesia with epidural morphine. Ketorolac (1 mg.kg-1 i.v. loading dose followed by 0.5 mg.kg-1 i.v. every six hr for 48 hr) was used as an adjunct to morphine in six patients. For management of postoperative muscle spasm, an intravenous benzodiazepine was used (diazepam 0.1 mg.kg-1 (n = 2), or midazolam infusion 10-30 micrograms.kg-1.hr-1 (n = 51)). All patients were cared for on a ward where nurses were familiar with the use of continuous opioid and benzodiazepine infusions. All patients received continuous cardiorespiratory monitoring as well as frequent nursing assessment. There were no episodes of postoperative apnoea or excessive sedation. We have found the use of continuous infusions of morphine and midazolam, along with adjunct ketorolac, to be effective in treating postoperative pain and muscle spasms following SDR.

The HPV response is different with constant pressure vs constant flow perfusion

Hypoxic pulmonary vasoconstriction (HPV) may be manifest in one of two ways: either an increase in the pulmonary artery pressure, or flow diversion away from the portion of the pulmonary bed with reduced conductance. We tested the hypothesis that the magnitude of the HPV response differs under conditions of constant flow perfusion, where pulmonary artery pressure (Ppa) rises during hypoxia, vs conditions of constant pressure perfusion, where Ppa remains constant and flow (Q) is diverted away from the lungs during hypoxia. In isolated, perfused rabbit lungs, the HPV response to four levels of hypoxia (12, 6, 3 and 0% oxygen) was of greater magnitude and more sustained under conditions of constant pressure perfusion as compared to constant flow perfusion. The possible significance of these findings as they relate to interpretation of studies in both the perinatal and mature pulmonary circulation is discussed.

Postoperative pain management in children

Postoperative pain management in children is a topic that has been neglected in the past but is currently an active field of interest and effort. Clearly, the child's cognitive understanding of and emotional response to pain are different than an adult's, and these differences make pain assessment and control more difficult. Ongoing work to develop more accurate techniques of estimating pain intensity in children may have helpful results. The effects of untreated pain in children are similar to those in adults but may have more long-term consequences in children. In the past, postoperative pain treatment in children was often inadequate, but newer techniques, such as continuous infusion of opioids, patient-controlled analgesia, epidural administration of opioids, and regional analgesia, hold promise for improved care in the future.

Aspiration in intubated premature infants

A recent study has shown a 77% incidence of tracheal aspiration in children (mean age 13.4 months) who are intubated with uncuffed endotracheal tubes. To determine both the incidence of such aspiration among premature infants and whether continuous positive airway pressure (CPAP) has any preventive effect, 20 tracheally intubated neonates were evaluated for the presence of tracheal aspiration of orally placed Evan's blue dye. The overall incidence of aspiration was 80%. Eighteen of these infants were tested during both 4 cm and 6 cm H2O continuous positive airway pressure, and the incidences of aspiration were 72% and 50%, respectively, which is not a statistically significant difference (P less than .17). Ten of these 18 patients were also studied when 2 cm H2O was applied and 60% aspirated. Among all infants who aspirated, compared with those who did not, there was a small but statistically significant decrease in transcutaneous PO2 (P less than .05) as well as an increase in respiratory (P less than .001) and pulse (P less than .01) rates. It is concluded that tracheally intubated neonates frequently aspirate and that clinically useful levels of continuous positive airway pressure are not likely to prevent aspiration.

Lung fluid balance in hypoxic lambs

In spontaneously breathing newborn lambs, alveolar hypoxia increases lung microvascular pressure, which causes lung lymph flow to increase and the concentration of protein in lymph to decrease. To see if this response derives from hypoxia itself rather than from the change in breathing pattern that occurs during hypoxia, we measured lung vascular pressures, pleural pressure, cardiac output, and lung lymph flow in 12 anesthetized lambs that were ventilated at a fixed rate and tidal volume, first with air, then with 10-14% O2 in nitrogen. Alveolar hypoxia did not affect pleural pressure, but pulmonary arterial pressure increased from 19 to 32 torr, lung lymph flow increased from 2.20 to 3.83 ml/h and lymph protein concentration decreased from 3.4 to 2.8 g/dl. To be certain that the increased lymph flow associated with hypoxia is not simply the result of an acute release of fluid from the lungs and to assess the effects of carbon dioxide on lymph flow during hypoxia, we next studied six unanesthetized lambs kept hypoxic for a total of 12 h. After a 2-4-h period in air the lambs breathed 9-11% O2 in nitrogen for 2-4 h, then 8-11% O2 and 3-5% CO2 in nitrogen for 8-10 h. In these lambs we injected intravenously radioactive albumin and measured its uptake in lymph to see if sustained hypoxia alters microvascular permeability to protein in the lungs. In these experiments pulmonary arterial pressure increased from 17 to 37 torr, lung lymph flow increased from 1.74 to 3.28 ml/h, and lymph protein concentration decreased from 3.8 to 3.1 g/dl during hypoxia.(ABSTRACT TRUNCATED AT 250 WORDS)

High intravenous phenytoin dosage requirement in a newborn infant

A term neonate was being treated with intravenous phenytoin. To maintain a serum level above 10 micrograms per milliliter and abolish seizure activity, it was necessary to carry out repeated serum concentration measurements, administer several loading doses, and administer an unusually large maintenance dose (25 mg per kilogram per day), divided into a short dosing interval (6 hours). Declining serum levels from postnatal days 8 to 13 on a constant dose of 9 mg per kilogram per day suggested that the rate of phenytoin metabolism was gradually increasing; rapid elimination was documented on day 18 by a half-life measurement of 8.8 hours from three samples. The changing pharmacokinetics were attributed to maturation of oxidative metabolism of phenytoin, concurrent phenobarbital administration, or both. The need for additional loading doses and maintenance dose increases must be guided by serum concentration measurements to obtain maximum benefit with minimal risk of toxicity.

Lung fluid balance in lambs before and after birth

To study lung fluid balance before and after birth, we measured lung lymph flow and concentrations of protein in lymph and plasma of 22 unanesthetized fetal lambs and compared results with previous studies done on 26 newborn lambs, 1-2 wk old. Lymph flow, relative to lung mass, was less in fetuses than in newborns; lymph protein clearance was not significantly different. Less lymph flow before birth probably reflects less available surface area for fluid exchange in microcirculation of fetal lungs, compared with newborn lungs, with no difference in endothelial permeability to protein. Extravascular lung water, measured gravimetrically for 24 fetuses (10 without labor, nine in labor, five 6 h after vaginal birth), decreased by 45% (15 +/- 2 g/kg body wt) before birth and by an additional 38% (6 +/- 1 g/kg) after birth. In five lambs killed after birth, we measured lung lymph flow before and during labor and for 6 h after breathing began. Lymph flow was unaffected by labor but increased transiently after birth, accounting for 11% of the liquid removed from lungs postnatally. Liquid clearance studies performed in eight anesthetized 3-wk-old lambs confirmed the observation that lung lymphatics drain only a small fraction of liquid in potential air spaces. Most of that liquid probably leaves the lungs directly through pulmonary circulation.

Power spectral analysis of the neonatal primate electroencephalogram during acute hypoxemia

The effect of acute graded hypoxemia on the electroencephalogram (EEG) of five prematures and five full term Macaca nemestrina in the neonatal period was determined using power spectral analysis--a technique that obviates the limitations of visual inspection. The EEG of selected epochs was analyzed by a Fast Fourier Transform program (POWER) during the 20 min of each trial of hypoxemia and compared with simultaneous arterial oxygen tensions. Levels of hypoxemia were graded as profound (PaO2=15-25 Torr); severe (PaO2=26-35 Torr), moderate (PaO2=36-50 Torr), or mild (PaO2=51-75 Torr). The EEG during normoxemia had a band width of 0.5 to 10 Hz and a peak power at 1-3 Hz. During mild hypoxemia, an increase in power in the delta range (0-3.5 Hz) occurred in the oldest animals. At moderate hypoxemia, the youngest animals showed a depression of absolute power in the delta band. A slowing of the EEG and decrease in power in the theta frequency range (4-8 Hz) followed when severe hypoxemic levels are reached. During profound hypoxemia, all animals at each postnatal age exhibited a significant decrease in EEG power at the delta and theta frequencies (P less than 0.025) except 3-wk-old full term animals in which there was no significant change in the delta band. These results clarify and extend previously reported effects of hypoxemia on the neonatal EEG.

Effect of hypercapnia on net filtration of fluid in the lungs of awake newborn lambs

To study the effect of hypercapnia on net transvascular filtration of fluid in newborn lungs, we measured pulmonary arterial and left pressures and collected lung lymph from 11 awake 2-wk-old lambs as they spontaneously breathed a gas mixture rich in carbon dioxide. After a 2-h control period in air, the lambs breathed 8-11% carbon dioxide mixed with air and nitrogen for 2-6 h. Average pulmonary arterial pressure and blood flow to the lungs increased during hypercapnia, but pulmonary vascular resistance did not change. In all cases, hypercapnia led to an acute transient increase in lymph flow. During sustained hypercapnia, however, flow of lymph was not significantly different from flow measured during the control period. The concentration of protein in lymph decreased at the onset of hypercapnia and remained low during sustained hypercapnia. These results suggest that acute hypercapnia increases net filtration by increasing the transvascular gradient of hydraulic pressure, whereas, in a "steady-state," neither hypercapnia nor the tachypnea that accompanies it alters net transvascular filtration of fluid in the lungs of unanesthetized newborn animals.

Lung fluid balance in hypoxic, awake newborn lambs and mature sheep

To study the pulmonary vascular response to hypoxia and associated transvascular flow of fluid into the lungs of newborn lambs and mature sheep, we collected lung lymph and measured pulmonary vascular pressures and blood flow in 14 unanesthetized lambs and 9 sheep breathing 10-12% oxygen for 3-6 h after a 2-hour control period in air. In both groups of animals, pulmonary arterial pressure, blood flow, and lung vascular resistance increased with hypoxia, but only in lambs did the flow of lymph increase and th concentration of protein in lymph decrease with hypoxia. These results suggest that hypoxia increased transvascular filtration of fluid into the lungs of the lambs by increasing hydraulic pressure in the pulmonary microcirculation. In sheep, the vascular response to hypoxia did not increase lung fluid filtration. Hypoxia had no effect on microvascular permeability to protein in the lungs of either group of animals.

The 'breech head' and its relevance

Eight infants had scaphocephaly with prominent occipital shelving. This abnormal head shape is identified as a postural deformation associated with breech intrauterine position, and it is noted to resolve during infancy with no apparent residual impairment in most cases. At the same time, the "breech head," as we have designated this unusual head form, may occur in the setting of a primary problem in fetal morphogenesis, and it may be itself a factor contributing to birth injury during vaginal delivery of the breech infant.

Eosinophilic gastroenteritis presenting as ileocolitis

An adolescent girl who presented with clinical and roentgenographic ileocolitis diagnosed as Crohn's disease was found to have histological evidence of eosinophilic gastroenteritis. The potential for colonic involvement in this disease is affirmed.