The effect of cisatracurium and rocuronium on lung function in anesthetized children.

BACKGROUND: Neuromuscular blocking drugs have been implicated in intraoperative bronchoconstrictive episodes. We examined the effects of clinically relevant doses of cisatracurium and rocuronium on the lung mechanics of pediatric subjects. We hypothesized that cisatracurium and rocuronium would have bronchoconstrictive effects. METHODS: We studied ASA physical status I and II pediatric subjects having elective dental or urological procedures, requiring general anesthesia with endotracheal intubations with either cisatracurium or rocuronium. Pulmonary function tests were performed before and after neuromuscular blocking drug dosing and again after albuterol administration. Using forced deflation and passive deflation techniques, forced vital capacity (FVC) and maximum expiratory flow rate at 10% (MEF10) of FVC were obtained. Fractional changes from the baseline were used to compare subjects. Changes in MEF10 of >30% were considered clinically significant. A Shapiro-Wilk test, paired t test, and Wilcoxon rank sum test were used to analyze the data. RESULTS: Twenty-five subjects (median age = 5.25 years; range = 9 months-9.9 years) were studied; 12 subjects received cisatracurium and 13 subjects received rocuronium. Data are shown as mean proportional change ± SD or, in the case of not normally distributed, median proportional change (first, third quartile) with P values. In the cisatracurium group, there were no differences between baseline and postneuromuscular blocker administration in the fractional change from the baselines of FVC (1.00 ± 0.04, P = 0.5), but there was a significant decrease in MEF10 (0.80 ± 0.18, P = 0.002). In the rocuronium group, there were small yet significant decreases of FVC (0.99 [first quartile 0.97, third quartile 1], P = 0.02) and significant decreases in MEF10 (0.78 ± 0.26, P = 0.008). After administration of albuterol in the cisatracurium group, FVC increased slightly but significantly from baseline values (1.02 ± 0.02, P = 0.005). MEF10 increased significantly beyond baseline values (1.24 ± 0.43, P =0.04). In the rocuronium group, there were also significant differences between baseline and postalbuterol administration from the baseline value of FVC (1.02 ± 0.02, P = 0.004) and MEF10 (1.23 ± 0.29, P = 0.01). CONCLUSIONS: At clinically relevant doses, both cisatracurium and rocuronium caused changes in lung function, indicating constriction of smaller airways. In general, these changes were mild and not clinically detectable. However, in the rocuronium group, 3 of 13 patients showed more noticeable decreases in MEF10 (≤50%), demonstrating the potential for significant broncho-bronchiolar constriction in susceptible patients.

Effects on lung function of multiple expansion thoracoplasty in children with thoracic insufficiency syndrome: a longitudinal study.

STUDY DESIGN: Longitudinal study of intraoperative pulmonary function in young children with thoracic hypoplasia and scoliosis undergoing multiple expansion thoracoplasty using the vertical expandable prosthetic titanium ribs (VEPTRs). OBJECTIVE: To test the long-term efficacy of VEPTR multiple expansion thoracoplasty. SUMMARY OF BACKGROUND DATA: To our knowledge, no direct measurements of pulmonary function have been reported with VEPTR expansion thoracoplasty. METHODS: There were 10 children with thoracic insufficiency syndrome, secondary to thoracic hypoplasia with progressive scoliosis, studied. A mobile pulmonary function laboratory unit was used to study forced vital capacity (FVC), maximum expiratory flow volume curves, and respiratory system compliance (Crs) with the patient under general anesthesia immediately before and after expansion thoracoplasty. Studies were repeated every 6 months at each subsequent operation for expansion thoracoplasty for the duration up to 33 months. RESULTS: At the baseline studies, FVC showed a moderate-to-severe decrease (69% of predicted values), indicating the presence of significant restrictive lung defect. Only 1 of 10 children had severe airway obstruction. The baseline Crs was markedly decreased in part because of the presence of significant atelectasis. Crs increased with an average of 42% after repeated hyperinflation (deep sighs). There was no change in lung volume or function immediately before versus after completion of expansion thoracoplasty. FVC increased significantly over time, with an average rate of 26.8% per year, the rate of increase similar to that of healthy children of comparative ages. In terms of percent-predicted values, FVC did not change significantly between the baseline and last test, indicating that in most children studied, lung growth kept up with body growth. CONCLUSION: Although it is difficult to assess the extent of the efficacy without a proper or historical control group for comparison, the present study indicates that in children with severe thoracic insufficiency syndrome, the insertion of VEPTRs with multiple expansion thoracoplasties is beneficial over time, by allowing the lungs to expand with body growth without further deterioration in lung function.

The future of the cuffed endotracheal tube.

It has been traditionally taught that only uncuffed endotracheal tubes (ETTs) should be used for intubation in children younger than 8, or even 10, years old. However, recent literature suggests that the advantages of using uncuffed ETTs in children may be just another myth of paediatric anaesthesia. Using an uncuffed ETT does allow a tube of larger internal diameter to be used, minimizing resistance to airflow and the work of breathing in the patient who is breathing spontaneously. However, this advantage does not hold for ventilated patients, for whom ventilator settings can be adjusted to provide optimal airflow. Longer duration of intubation and a poorly fitted ETT are risk factors for mucosal damage, whether the ETT is cuffed or uncuffed. Furthermore, a properly sized, positioned, and inflated modern (low-pressure, high-volume) cuffed ETT can offer many advantages over an uncuffed ETT, including greater ease of intubation, better control of air leakage, lower rate and better control of flow of anaesthetic gases, and decreased risk of aspiration and infection.

The effect on lung mechanics in anesthetized children with rapacuronium: a comparative study with mivacurium.

UNLABELLED: The administration of rapacuronium increases the risk of severe bronchospasm. There have been no studies of pulmonary function directly demonstrating airway constriction with rapacuronium in children. In this study, 10 ASA physical status I or II patients (aged 2-6 yr) were randomly divided into 2 equal groups, receiving either rapacuronium or mivacurium. Anesthesia was induced with sevoflurane and maintained with remifentanil (0.2-0.3 microg. kg(-1). min(-1)) and propofol (200-250 microg. kg(-1). min(-1)) infusions. We performed three sets of pulmonary function tests: baseline, after the administration of muscle relaxant, and after the administration of a beta(2) agonist. In both groups, there were no changes in static respiratory compliance. The increase in total respiratory system resistance after the administration of rapacuronium did not reach statistical significance (214.4% +/- 122.65% of baseline, P approximately 0.1), whereas maximal expiratory flow at 10% of forced vital capacity (MEF)(10) and MEF(functional residual capacity) on partial flow-volume curves by the forced deflation technique decreased markedly (53.4% +/- 18.49%, P < 0.01 and 41.3% +/- 27.42%, P < 0.001, respectively). With the administration of mivacurium, no changes were observed in respiratory system resistance (109.5% +/- 30.28%). MEF(10) decreased slightly (77.0% +/- 9.03%, P < 0.005) whereas MEF(FRC) did not (81.2% +/- 29.85%, not significant). After the administration of a beta(2) agonist, all measurements returned to baseline. Thus, the administration of rapacuronium consistently results in lower airway obstruction with minimal changes in static respiratory compliance when compared with mivacurium. IMPLICATIONS: Pulmonary function tests in the present study showed that rapacuronium consistently causes severe bronchoconstriction, confirming clinical case reports of bronchospasm. The bronchoconstriction is reversible with albuterol. Mivacurium also causes very mild subclinical bronchoconstriction.

Predicting recovery from deep neuromuscular block by rocuronium in children and adults.

STUDY OBJECTIVE: To compare the response to motor nerve stimulation at a rate of 1 Hz after 50 Hz tetanus [posttetanic count (PTC)] and 2 Hz for 2 seconds [train-of-four (TOF)] in children and adults during spontaneous recovery from blockade caused by rocuronium. DESIGN: Prospective, clinical, observational, multicenter study. SETTING: Operating rooms of two university hospitals. PATIENTS: 22 children (ASA physical status I and II) aged 2 to 5 years, scheduled to undergo dental treatment and 20 adults aged 18 to 60 years, scheduled to undergo elective general or orthopedic surgery during general anesthesia with tracheal intubation. MEASUREMENTS: Neuromuscular blockade was evaluated with accelerometry of the thumb, using PTC and TOF stimulation of the ulnar nerve, in patients who received rocuronium 1 mg x kg(-1). MAIN RESULTS: The first response to posttetanic and TOF nerve stimulation appeared earlier in children than in adults. The time from injection of rocuronium to appearance of the fourth response to TOF ranged from 27 to 62 minutes in children and from 37 to 94 minutes in adults. The average interval between the appearance of a posttetanic response and the first detectable response to TOF stimulation (T1) was also shorter in children, 7 minutes, than in adults, 16 minutes. The relationship between PTC and the time interval between a given PTC and the first detectable TOF response in both children and adults was exponential (R = -0.64 and R = -0.81, respectively). CONCLUSIONS: Children recover faster than adults from neuromuscular blockade after administration of 1 mg x kg(-1) rocuronium. The relationship between PTC and time to first response to TOF is exponential both in children and adults during recovery from neuromuscular blockade caused by rocuronium.

Neuromuscular blocking drugs in pediatric anesthesia.

There are differences between pediatric patients and adults in the responses to neuromuscular blockers. The results of new studies of neuromuscular blockers in pediatric patients are generally consistent with earlier studies in the type of age-related differences documented. Surprising new results are the side effects, including anaphylaxis, that have been observed, and studied directly, in pediatric patients. Continued evaluation of these drugs in pediatric patients will provide better information regarding the variability of the effects of neuromuscular blockers in healthy and diseased infants and children.