Role of muscle relaxants in pediatric anesthesia

Spontaneous recovery from neuromuscular block after a single dose of a muscle relaxant in pediatric patients: A systematic review using a network meta-analytic and meta-regression approach

BACKGROUND

Age-related differences in the pharmacokinetics and pharmacodynamics of neuromuscular blocking agents (NMBAs) and the short duration of many surgical procedures put pediatric patients at risk of postoperative residual curarization (PORC). To date, the duration of neuromuscular blocking agent effect in children has not been analyzed in a quantitative review. The current meta-analysis aimed to compare spontaneous recovery following administration of various types and doses of neuromuscular blocking agents and to quantify the effect of prognostic variables associated with the recovery time in pediatric patients.

METHOD

We searched for randomized controlled trials (RCTs) and controlled clinical trials (CCTs) that compared the time to 25% T1 (t25), from 25% to 75% T1 (RI25-75), and to ≥90% train-of-four (tTOF90) neuromuscular recovery between common neuromuscular blocking agent treatments administered as a single bolus to healthy pediatric participants. We compared spontaneous t25, RI25-75, and tTOF90 between (1) neuromuscular blocking agent treatments and (2) age groups receiving a given neuromuscular blocking agent intervention and anesthesia technique. Bayesian random-effects network and pairwise meta-analyses along with meta-regression were used to evaluate the results.

RESULTS

We used data from 71 randomized controlled trials/controlled clinical trials including 4319 participants. Network meta-analysis allowed for the juxtaposition and ranking of spontaneous t25, RI25-75, and tTOF90 following common neuromuscular blocking agent interventions. For all neuromuscular blocking agents a log-linear relationship between dose and duration of action was found. With the neuromuscular blocking agent treatments studied, the average tTOF90 (mean[CrI95]) in children (>2-11 y) was 41.96 [14.35, 69.50] and 17.06 [5.99, 28.30] min shorter than in neonates (<28 d) and infants (28 d-12 M), respectively. We found a negative log-linear correlation between age and duration of neuromuscular blocking agent effect. The difference in the tTOF90 (mean[CrI95]) between children and other age groups increased by 21.66 [8.82, 34.53] min with the use of aminosteroid neuromuscular blocking agents and by 24.73 [7.92, 41.43] min with the addition of sevoflurane/isoflurane for anesthesia maintenance.

CONCLUSIONS

The times to neuromuscular recovery are highly variable. These can decrease significantly with age and are prolonged when volatile anesthetics are administered. This variability, combined with the short duration of many pediatric surgical procedures, makes quantitative neuromuscular monitoring mandatory even after a single dose of neuromuscular blocking agent.

Pharmacologic Adjuncts for Neonatal Tracheal Intubation: The Evidence Behind Premedication

Premedication such as analgesia, sedation, vagolytics, and paralytics may improve neonatal tracheal intubation success, reduce intubation-associated adverse events, and create optimal conditions for performing this high-risk and challenging procedure. Although rapid sequence induction including a paralytic agent has been adopted for intubations in pediatric and adult critical care, neonatal clinical practice varies. This review aims to summarize details of common classes of neonatal intubation premedication including indications for use, medication route, dosage, potential adverse effects in term and preterm infants, and reversal agents. In addition, this review shares the literature on national and international practice variations; explores evidence in support of establishing premedication guidelines; and discusses unique circumstances in which premedication use has not been established, such as during catheter-based or minimally invasive surfactant delivery. With increasing survival of extremely preterm infants, clear guidance for premedication use in this population will be necessary, particularly considering potential short- and long-term side effects of procedural sedation on the developing brain.

Airway Management in Pediatric Patients: Cuff-Solved Problem?

Traditionally, uncuffed tubes were used in pediatric patients under 8 years in pursuit of reducing the risk of postextubation stridor. Although computed tomography and magnetic resonance imaging studies confirmed that the subglottic area remains the narrowest part of pediatric airway, the use of uncuffed tubes failed to reduce the risk of subglottic swelling. Properly used cuffed tubes (correct size and correct cuff management) are currently recommended as the first option in emergency, anesthesiology and intensive care in all pediatric patients. Clinical practice particularly in the intensive care area remains variable. This review aims to analyze the current recommendation for airway management in children in emergency, anesthesiology and intensive care settings.

Rocuronium reversed with sugammadex for thymectomy in myasthenia gravis: A retrospective analysis of complications from Japan

BACKGROUND

Postoperative respiratory failure is a serious problem in the anaesthetic management of patients with myasthenia gravis who undergo thymectomy. Although the classical recommendation is to avoid neuromuscular blockers, there is no strong evidence to support it.

OBJECTIVES

To evaluate the postoperative outcomes in patients with myasthenia gravis after thymectomy when anaesthetic management included rocuronium reversed with sugammadex.

DESIGN

A retrospective cohort study.

SETTING

Nationwide acute in-patient care database.

PATIENTS

A total of 1143 patients with myasthenia gravis who underwent thymectomy were included. Data were collected from the medical insurance claims data of acute care in-patient hospitals.

MAIN OUTCOME MEASURES

The postoperative complications when rocuronium reversed with sugammadex was compared against no muscle relaxant use using propensity score matching. The primary outcomes were the rates of in-hospital mortality, plasma exchange following thymectomy and the use of immunoglobulins. The secondary outcomes were the length of stay in the high dependency/ICUs, the total length of hospital stay and the duration and type of respiratory support following thymectomy.

RESULTS

There were no significant differences between the propensity score matched groups in terms of plasma exchange [relative risk, 0.96; 95% confidence interval (CI), 0.64 to 1.43] and use of immunoglobulins (relative risk, 1.09; 95% CI, 0.60 to 1.97). The length of hospital stay was significantly shorter in patients in whom rocuronium and sugammadex were used: 29.0 vs. 35.4 days, P = 0.035.

CONCLUSIONS

Anaesthetic management with rocuronium reversed by sugammadex was not associated with increased risk of respiratory complications. These findings could help in the anaesthetic management of patients with myasthenia gravis.

Effects of neuromuscular blocking agents on the clinical performance of i-gel® and surgical condition in elderly patients undergoing hand surgery: a prospective randomized controlled trial

Background: The effects of neuromuscular blocking agents on the clinical performance of supraglottic airway devices and surgical condition in elderly patients undergoing hand surgery have not been established. We evaluated the effects of rocuronium on the clinical performance of an i-gel^® supraglottic device and surgical condition in elderly patients undergoing orthopedic hand surgery. Methods: Patients aged 65-85 years were randomized to receive either rocuronium (rocuronium group) or saline (control group). We compared the rates of successful insertion of the i-gel on the first attempt as a primary outcome and also assessed the adequacy of i-gel maintenance during controlled ventilation, anesthetic requirement, surgical condition, and recovery time. Results: The rates of successful insertion of the i-gel on a first attempt were 93.1% in the rocuronium group versus 82.1% in the control group (P = 0.423). Peak inspiratory pressure (PIP) was lower in the rocuronium group than in the control group (15.2 vs. 17.9 cmH₂O, respectively, P = 0.028). Spontaneous breathing was less common in the rocuronium group (24.1% vs. 57.1%, respectively, P = 0.011). The requirement of additional fentanyl to suppress spontaneous breathing or patient movement was less in the rocuronium group than in the control group (24.1% vs. 50.0%, respectively, P = 0.043). Surgical condition did not differ between the two groups. Recovery time was shorter in the rocuronium group than in the control group (8.4 vs. 9.9 min, respectively, P = 0.030). Conclusions: Rocuronium did not enhance the success rate of inserting the i-gel^® or the surgical condition in elderly patients. However, using rocuronium reduced PIP, the frequency of spontaneous breathing, the requirement for additional fentanyl and patients' recovery time.

Current use of neuromuscular blocking agents and antagonists in Korea: a 2018 survey

Background

Neuromuscular blocking agents (NMBAs) and neuromuscular monitoring in anesthetic management are integral for endotracheal intubation, better visualization of the surgical field, and prevention of residual neuromuscular blockade and pulmonary complications. Sugammadex is a drug that reduces risk of residual neuromuscular blockade, with more rapid recovery compared to anticholinesterase. The purpose of this study was to investigate current usage status of NMBAs and antagonist with neuromuscular monitoring, among anesthesiologists in Korea.

Methods

Anesthesiologists working in Korea were invited to participate in an online survey via email January 2–February 28, 2018. The questionnaire consisted of 45 items, including preferred NMBAs, antagonists, neuromuscular monitoring, and complications related to the use sugammadex. A total of 174 responses were analyzed.

Results

Rocuronium was a commonly used NMBA for endotracheal intubation (98%) of hospitals, and maintenance of anesthesia (83.3%) in of hospitals. Sugammadex, pyridostigmine, and neostigmine were used in 89.1%, 87.9%, and 45.4% of hospitals. Neuromuscular monitoring was employed in 79.3% of hospitals; however only 39.7% of hospitals used neuromuscular monitoring before antagonist administration. Usual dosage range of sugammadex was 2.1–4 mg/kg in 35.1% of hospitals, within 2 mg/kg in 34.5% of hospitals, and 1 vial regardless of body weight in 22.4% of hospitals. Sugammadexrelated complications were encountered by 14.9% of respondents.

Conclusions

This survey indicates several minor problems associated with the use of antagonists and neuromuscular monitoring. However, most anesthesiologists appear to have appropriate information regarding the usage of NMBAs and sugammadex.

A framework for the management of the pediatric airway

Critical airway incidents in children are a frequent problem in pediatric anesthesia and remain a significant cause of morbidity and mortality. Young children are at particular risk in the perioperative period. Delayed management of airway obstruction can quickly lead to serious complications due to the short apnea tolerance in children. A simple, time critical, and pediatric-specific airway management approach combined with dedicated teaching, training, and frequent practice will help to reduce airway-related pediatric morbidity and mortality. There is currently no pediatric-specific universal framework available to guide practice. Current algorithms are modifications of adult approaches which are often inappropriate because of differences in age-related anatomy, physiology, and neurodevelopment. A universal and pragmatic approach is required to achieve acceptance across diverse pediatric clinicians, societies, and groups. Such a framework will also help to establish minimum standards for pediatric airway equipment, personnel, and medications whenever pediatric airway management is required.

Comparison of the clinical performance of the flexible laryngeal mask airway in pediatric patients under general anesthesia with or without a muscle relaxant: study protocol for a randomized controlled trial

BACKGROUND

The insertion of a laryngeal mask airway (LMA) is difficult in children due to the unique features of their airways. Muscle relaxants have been reported to facilitate LMA insertion in adults; however, there is a lack of evidence supporting this in children. This trial is designed to assess the feasibility of LMA insertion with and without the use of muscle relaxants in pediatric patients under general anesthesia.

METHODS/DESIGN

This is a prospective, double-blind, single-center, parallel-arm, non-inferiority, randomized controlled trial to be conducted with participants aged 2-7 years who are undergoing elective ophthalmic surgery under general anesthesia. Participants are randomly assigned to one of two groups based on whether muscle relaxants are used (MR group, n = 64) or not used (Saline group, n = 64) prior to LMA insertion. The primary outcome is the oropharyngeal leak pressure (OLP) at a fixed gas flow of 3 L/min. The secondary outcomes are intubation time for successful insertion, ease of insertion and mask bagging, intubation attempt for successful insertion, successful insertion rate on the first attempt, fiberoptic view of the LMA position, postoperative complications, and changes in hemodynamic and ventilatory parameters.

DISCUSSION

We will compare the OLPs to determine whether the muscle relaxant provides better conditions for the manipulation of the LMA. This is the first randomized controlled trial to investigate whether muscle relaxants are beneficial to the clinical performance of LMA insertion in pediatric patients under general anesthesia. This trial will be a resource for improving the process and safety of pediatric LMA insertion under general anesthesia.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT03487003 . Registered on 18 April 2018.

Pharmacology related to paediatric anaesthesia

A child is not a mini adult. They differ from adults in terms of weight, shape, anatomical size and major body systems such as cardiovascular and respiratory as well as psychologically. Each organ system is immature in paediatric age group and their growth and development can dramatically affect the pharmacokinetics of different drugs. Children differ in every way from an adult thus mandating to have a basic knowledge of the pharmacokinetic and pharmacodynamic principles in paediatric population to prevent under dosing or toxicity of drugs. This review article aims to simplify the basic principles of pharmacokinetics and pharmacodynamics in paediatric population. It also highlights physiological and pharmacological differences between adults and paediatric age. We performed a PUBMED search for English language articles using keywords including pharmacology, child, paediatric anaesthesia. We also hand searched references from relevant review articles and text book chapters. We have also discussed drug interaction in anaesthesia, pharmacology pertaining to neuromuscular junction and effects of anaesthesia over the developing brain.

Pediatric Cardiac Intensive Care Society 2014 Consensus Statement: Pharmacotherapies in Cardiac Critical Care: Sedation, Analgesia and Muscle Relaxant

OBJECTIVE

This article reviews pharmacotherapies currently available to manage sedation, analgesia, and neuromuscular blockade for pediatric cardiac critical patients.

DATA SOURCES

The knowledge base of an expert panel of pharmacists, cardiac anesthesiologists, and a cardiac critical care physician involved in the care of pediatric cardiac critical patients was combined with a comprehensive search of the medical literature to generate the data source.

STUDY SELECTION

The panel examined all studies relevant to management of sedation, analgesia, and neuromuscular blockade in pediatric cardiac critical patients.

DATA EXTRACTION

Each member of the panel was assigned a specific subset of the studies relevant to their particular area of expertise (pharmacokinetics, pharmacodynamics, and clinical care) to review and analyze.

DATA SYNTHESIS

The panel members each crafted a comprehensive summary of the literature relevant to their area of expertise. The panel, as a whole, then collaborated to cohesively summarize all the available, relevant literature.

CONCLUSIONS

In the cardiac ICU, management of the cardiac patient requires an individualized sedative and analgesic strategy that maintains hemodynamic stability. Multiple pharmacological therapies exist to achieve these goals and should be selected based on the patient's underlying physiology, hemodynamic vulnerabilities, desired level of sedation and analgesia, and the projected short- or long-term recovery trajectory.

The management of difficult intubation in infants: a retrospective review of anesthesia record database

We retrospectively reviewed the anesthesia records of infants < 1 year of age for elucidating the incidence of difficult intubation and airway management in a single general hospital. The electronic data records from a total of 753 consecutive anesthesiological procedures in 513 different infants were analyzed. After excluding data with a lack of records of laryngoscopic findings, a total of 497 procedures (389 different infants) with either remarks of difficult intubation (requiring > 10 min for tracheal intubation) or records of Cormack-Lehane grade were included. Demographic data are median age 5 (range, 0–11) months, height 61 (33–84) cm, body weight 6.0 (1.1 − 11.8) kg. The number of cases with ASA physical status I, II, III and IV was 182 (36.6 %), 135 (27.3 %), 177 (35.5 %) and 3 (0.6 %), respectively. Cormack-Lehane grade 1, 2, 3 and 4 was seen in 450 (90.5 %), 32 (6.4 %), 6 (1.2 %) and 6 (1.2 %) cases, respectively.

Document of difficult intubation was found in 12 cases (2.4 %, 10 different infants) with a lack of record of Cormack-Lehane grade in 3 cases. Of these 10 infants, nine had multiple congenital anomalies including heart diseases and cleft palate. Without premedication, general anesthesia was induced with intravenous midazolam or sevoflurane in the 12 cases. Tracheal intubation was performed after disappearance of spontaneous respiration except three cases who were intubated in the awake state or under sedation. Elapsed time from induction of anesthesia to intubation was 17 (14–29) min. Although mask ventilation was adequate in all cases, two cases (one infant) developed hypoxia and bradycardia during tracheal intubation. No remarkable decrease of SpO₂ or bradycardia less than 100 bpm was detected in other cases. In conclusion, we found difficult intubation in 2.4 % of infants undergoing general anesthesia. Although muscle relaxants are useful for facilitating tracheal intubation, it should be carefully used with the preparation of other airway devices in infants with predicted difficult intubation.

Appropriate sevoflurane concentration to stabilize autonomic activity during intubation with rocuronium in infants: a randomized controlled trial

Background

In infants, sevoflurane is commonly used for induction of anesthesia, following which a muscle relaxant is administered to facilitate tracheal intubation. When rocuronium is used as the muscle relaxant, intubation may be performed before reaching an adequate depth of anesthesia because of its rapid onset. The purpose of this study was to investigate the optimal sevoflurane concentration that would minimize the impact of intubation on hemodynamics and autonomic nervous system (ANS) activity in infants.

Methods

Sixty-one infants aged 1–6 months, undergoing cleft lip repair, were enrolled. Patients were randomly assigned to three end-tidal sevoflurane concentration (E’_Sevo) groups, 3%, 4% and 5%. Anesthesia was induced with 5% sevoflurane with 100% oxygen, and rocuronium (0.6 mg/kg) was administered. The concentration of sevoflurane was adjusted to the predetermined concentration in each group. Mechanical pressure control ventilation via a face mask was commenced. Five minutes after E’_Sevo became stable at the predetermined concentration, tracheal intubation was performed. Immediately after tracheal intubation, ventilation was restarted at the same ventilator settings and continued for 150 seconds. Heart rate (HR) and mean arterial pressure (MAP) were measured 5 times in the 150 seconds after intubation. Normalized units (nu) of high frequency (HF: 0.04-0.15 Hz) and the ratio of low frequency (LF: 0.15-0.4 Hz) to HF components (LF/HF) of HR variability were calculated by MemCalc/Tonam2C™. Normalized units of HF (HFnu) and LF/HF reflect cardiac parasympathetic and sympathetic activity, respectively.

Results

After intubation, HR increased slightly in all groups and MAP increased by 9.2% in the E’_Sevo-3% group. LF/HF increased (p < 0.01) and HFnu decreased (p < 0.01) in all groups 30 seconds after intubation. HFnu was lower (p < 0.001) and LF/HF was higher (p = 0.007) in the E’_Sevo-3% group than in E’_Sevo-5% group. ANS responses to intubation were reduced in a dose-dependent manner.

Conclusions

Sympathomimetic and parasympatholytic responses to intubation in the E’_Sevo-3% group were much greater than those in the E’_Sevo-5% group. During tracheal intubation in infants, 4% or 5% sevoflurane is appropriate for prevention of sympathetic hyperactivation and maintenance of ANS balance as compared to 3% sevoflurane, when a muscle relaxant is co-administered.

Trial registration

The study was registered at UMIN-CTR (UMIN000009933).

Supraglottic airway devices vs tracheal intubation in children: a quantitative meta-analysis of respiratory complications

BACKGROUND

Rate of perioperative respiratory complications between tracheal intubation (TI) and laryngeal mask airway remains unclear during pediatric anesthesia.

OBJECTIVES

The aim of the present meta-analysis was to compare the perioperative respiratory complications between laryngeal mask airway and TI.

METHODS

A meta-analysis of available controlled studies comparing laryngeal mask airway to TI was conducted. Studies including patients with airway infection were excluded. Data from each trial were combined to calculate the pooled odds ratios (OR) or mean difference (MD) and 95% confidence intervals.

RESULTS

The meta-analysis was performed on 19 studies. In 12 studies, patients were given muscle relaxation, and in 16 studies, ventilation was controlled. During recovery from anesthesia, the incidence of desaturation (OR = 0.34 [0.19-0.62]), laryngospasm (OR = 0.34 [0.2-0.6]), cough (OR = 0.18 [0.11-0.27]), and breath holding (0.19 [0.05-0.68]) was lower when laryngeal mask airway was used to secure the airway. Postoperative incidences of sore throat (OR = 0.87 [0.53-1.44]), bronchospasm (OR = 0.56 [0.25-1.25]), aspiration (1.33 [0.46-3.91]) and blood staining on the device (OR = 0.62 [0.21-1.82]) did not differ between laryngeal mask airway and TI. Results were homogenous across the studies, with the exceptions of blood staining on the device.

CONCLUSIONS

This meta-analysis found that the use of laryngeal mask airway in pediatric anesthesia results in a decrease in a number of common postanesthetic complications. It is therefore a valuable device for the management of the pediatric airway.

Effect-site concentration of remifentanil for nasotracheal versus orotracheal intubation during target-controlled infusion of propofol

The concentration of remifentanil required for acceptable nasotracheal intubation in adults after target-controlled infusion (TCI) of propofol without neuromuscular blockade was compared with that required for orotracheal intubation. Twenty-five patients undergoing oral and maxillofacial surgery received nasotracheal intubation and 25 undergoing ear, nose and throat surgery received orotracheal intubation. Anaesthesia was induced with propofol TCI at a target effect-site concentration of 5.0 μg/ml. The 50% and 95% effective concentrations (EC(50) and EC(95), respectively) for remifentanil, calculated using isotonic regression, were 5.40 and 6.85 ng/ml, respectively, in the orotracheal group and 5.75 and 7.43 ng/ml in the nasotracheal group. The EC(50) (± SD) values for remifentanil, calculated using a modified Dixon's up-and-down method, were 6.08 ± 0.75 and 5.58 ± 0.75 ng/ml for nasotracheal and orotracheal intubation, respectively. Effect-site remifentanil concentrations did not differ significantly between the two groups of patients. Coadministration of propofol and remifentanil can provide acceptable conditions for nasotracheal intubation without neuromuscular blockade.

Continuous-infusion neuromuscular blocking agents in critically ill neonates and children

Neuromuscular blocking agents (NMBAs) are often administered as a prolonged (> 24 hrs) continuous infusion in infants and children in the intensive care unit for a variety of reasons including facilitation of oxygenation and ventilation. No guidelines on the use of NMBAs in pediatric patients are available yet in the United States; however, pediatric guidelines are available in the United Kingdom. Based on a 2007 U.S. survey, the most commonly used nondepolarizing NMBAs for sustained neuromuscular blockade in critically ill children are pancuronium and vecuronium. Recent national drug shortages involving NMBAs have been reported for atracurium, cisatracurium, pancuronium, rocuronium, and vecuronium. Therefore, to explore alternative options for neuromuscular blockade, we conducted a literature search to identify articles evaluating prolonged use (> 24 hrs) of NMBAs administered by continuous infusion. The search was limited to English-language articles in the MEDLINE (1950-August 2010), EMBASE (1988-August 2010), International Pharmaceutical Abstracts (1970-August 2010), and Cochrane Library (1996-August 2010) databases. Relevant abstracts, reference citations, and manufacturers' product information were also reviewed. A total of 13 reports representing 208 children were included in the analysis. Many of the reports described wide interpatient variability in dosing for the specific NMBAs evaluated. Selection of the most appropriate NMBA should be based on the patient's clinical status, potential adverse effects, and pharmacoeconomics. All patients receiving sustained neuromuscular blockade should be monitored routinely to ensure that dosing is appropriate in order to obtain the desired level of blockade. The goal is to use the lowest dose possible in an effort to limit adverse effects or prolonged blockade.

Propofol for tracheal intubation in children anesthetized with sevoflurane: a dose-response study

BACKGROUND

Tracheal intubation during sevoflurane induction is frequently facilitated with i.v. propofol. We designed a dose-response study to evaluate the intubating conditions, and the incidence and duration of apnea after i.v. propofol in children.

METHODS/MATERIALS

Sixty healthy children were randomly assigned to 0, 0.5, 1, 2 or 3 mg x kg(-1) i.v. propofol during sevoflurane/nitrous oxide anesthesia. Tracheal intubation was performed approximately 30 s after propofol by an anesthesiologist who was blind to the treatment. The anesthesiologist assessed the responses to laryngoscopy and intubation using a standardized scale. Incidence and duration of apnea after propofol as well as heart rate, and systolic blood pressure before and after laryngoscopy were recorded. Data were analyzed using one-way and repeated measures ANOVA, the Jonckheere-Terpstra test, and logistic regression, with P < 0.05 accepted.

RESULTS

The laryngoscopy score after 3 mg x kg(-1) propofol was less than that after 0 mg x kg(-1) (P < 0.01) and 0.5 mg x kg(-1) (P < 0.05). Incidence of apnea after propofol 3 mg x kg(-1), 8/10, was greater than after 0 mg x kg(-1), 3/14 (P < 0.011) and 0.5 mg x kg(-1), 3/12 (P < 0.03). Duration of apnea after 3 mg x kg(-1) was greater than after 0 and 0.5 mg x kg(-1) (P < 0.01). The risk of apnea increased 1.83 fold for each 1 mg x kg(-1) dose increase in propofol (P < 0.01). Mean heart rate and systolic pressure decreased with the main effect, time.

CONCLUSION

During sevoflurane/nitrous oxide anesthesia, propofol 3 mg x kg(-1) provides superior intubating conditions with an increased incidence of and prolonged apnea compared with 0 and 0.5 mg x kg(-1).

Effect of muscle relaxants on short-term results of exotropia surgery: a focus on resection procedures

Purpose

We investigated the effect of muscle relaxants (atracurium) on the outcomes of intermittent exotropia surgery under general anesthesia, with a focus on resection procedures.

Methods

Thirty four patients who underwent recession and resection (R&R) were divided into two groups: atracurium usage (group A, n=18) and no atracurium usage (group B, n=16). Patients were divided into two subgroups according to the amount of resection of the medial rectus (MR): less than 5 mm (group 1, n=13) or 5 mm and greater (group 2, n=21). Deviation angles were compared between groups and subgroups. Surgical outcome was defined as successful if distant deviation angles were equal to or less than 10 prism diopters.

Results

The overall postoperative deviation angles did not show statistically significant differences between groups A and B. However, in patients with larger MR resections (≥ 5 mm), the 1 week postoperative distant deviation was significantly larger in group A (1.8±2.6 PD) than in group B (-1.6±4.6 PD, p=0.048 by t-test). The overall undercorrection rate at 3 months postoperatively for group A was 16.7%, which was higher than that of group B (6.3%), and the difference was even larger in subgroups with larger MR resections (≥ 5 mm): 18.2% in group A and 0% in group B.

Conclusions

Patients who underwent R&R procedures under general anesthesia with a muscle relaxant tended to be less corrected than those without muscle relaxant, especially in the early postoperative period and with a larger MR resection equal to or greater than 5 mm. However, there was no significant difference in the later postoperative period.