Rocuronium-induced respiratory paralysis refractory to sugammadex in Charcot-Marie-Tooth disease.

PURPOSE: Prolonged postoperative neuromuscular respiratory paralysis after administration of a nondepolarizing neuromuscular blocking agent is a serious concern during anesthetic management of patients with Charcot-Marie-Tooth disease (CMTD). Some recent reports have described rocuronium use without respiratory paralysis in CMTD patients when sugammadex was used for its reversal. We report a case in which an induction dose of rocuronium caused a prolonged respiratory paralysis in a patient with undiagnosed type 1A CMTD (CMT1A). CLINICAL FEATURES: A 63-yr-old-male with an American Society of Anesthesiologists Physical Status score of III underwent a left hip arthroplasty under general anesthesia for osteoarthritis. Preoperative pulmonary function testing indicated a restrictive impairment. Anesthesia was induced with fentanyl, remifentanil, propofol, and 0.73 mg·kg-1 of rocuronium. The train-of-four (TOF) count was 0 for the 273-min duration of surgery. After repeated doses of sugammadex failed to recover the TOF count and spontaneous respirations, a total of 1,200 mg (17.3 mg·kg-1) of sugammadex, which was assumed to be a sufficient amount for capturing the residual rocuronium, was administered. Although the patient expressed that he was awake via eye blinking, he could not breathe. Thus, he was placed on mechanical ventilation for 18 hr after surgery. A postoperative neurology consultation revealed a delayed nerve conduction velocity of 20 m·sec-1 and a mutated duplication of the PMP22 gene; a diagnosis of CMT1A was made. CONCLUSIONS: Our case shows that rocuronium can cause a prolonged neuromuscular respiratory paralysis refractory to sugammadex in patients with CMT1A and impaired respiratory function. Our case may also indicate that restrictive pulmonary impairment and low nerve conduction velocity of 20 m·sec-1 are predictive factors that cause prolonged neuromuscular respiratory paralysis refractory to sugammadex in CMT1A.

RéSUMé: OBJECTIF: La paralysie respiratoire neuromusculaire postopératoire prolongée après l'administration d'un bloqueur neuromusculaire non dépolarisant est une préoccupation sérieuse lors de la prise en charge anesthésique des patients atteints de la maladie de Charcot-Marie-Tooth (CMT). Certains comptes rendus récents ont décrit l'utilisation de rocuronium sans paralysie respiratoire chez les patients atteints de CMT lorsque le sugammadex était utilisé pour le neutraliser. Nous rapportons un cas dans lequel une dose d'induction de rocuronium a provoqué une paralysie respiratoire prolongée chez un patient atteint de CMT de type 1A (CMT1A) non diagnostiquée. CARACTéRISTIQUES CLINIQUES: Un homme de 63 ans avec un score de statut physique III selon la classification de l'American Society of Anesthesiologists a bénéficié d'une arthroplastie de la hanche gauche sous anesthésie générale pour son ostéo-arthrite. Les tests préopératoires de la fonction pulmonaire ont indiqué un syndrome restrictif. L'anesthésie a été induite avec du fentanyl, du rémifentanil, du propofol et 0,73 mg·kg-1 de rocuronium. Le décompte du train-de-quatre (TdQ) était de 0 pour toute la durée de la chirurgie, soit 273 minutes. Après l'échec de doses répétées de sugammadex qui n'ont pas réussi à rétablir un TdQ normal ni la respiration spontanée, un total de 1200 mg (17,3 mg·kg-1) de sugammadex (une quantité qu'on a présumé suffisante pour neutraliser le rocuronium résiduel) a été administré. Bien que le patient ait exprimé qu'il était éveillé en clignant des yeux, il ne pouvait pas respirer. Il a donc été placé sous ventilation mécanique pendant 18 heures après l'opération. Une consultation postopératoire en neurologie a révélé une vitesse de conduction nerveuse retardée de 20 m·sec-1 et une duplication mutée du gène PMP22; un diagnostic de CMT1A a été posé. CONCLUSIONS: Notre cas montre que le rocuronium peut provoquer une paralysie respiratoire neuromusculaire prolongée réfractaire au sugammadex chez les patients atteints de CMT1A et d'une altération de la fonction respiratoire. Notre cas pourrait également indiquer qu'un syndrome restrictif pulmonaire et une faible vitesse de conduction nerveuse de 20 m·sec-1 constituent des facteurs prédictifs provoquant une paralysie respiratoire neuromusculaire prolongée réfractaire au sugammadex dans les cas de CMT1A.

Efficacy and safety of sugammadex for neuromuscular blockade reversal in pediatric patients: an updated meta-analysis of randomized controlled trials with trial sequential analysis.

BACKGROUND: A recent survey revealed that extensive off-label use of sugammadex in pediatric anesthesia deserved particular attention. The present study with trial sequential analysis (TSA) aimed to evaluate the effects of sugammadex for antagonizing neuromuscular blockade (NMB) in pediatric patients, and to investigate whether the findings achieved the required information size to draw conclusions. METHODS: PubMed, Embase, Cochrane Library and China National Knowledge Infrastructure (CNKI) were searched from inception to April 2021. All randomized controlled trials used sugammadex as reversal agent in pediatric patients were enrolled. Time from NMB reversal to recovery of the train-of-four ratio (TOFr) to 0.9 and extubation time were considered as co-primary outcomes, and incidences of adverse events were considered as secondary outcomes. Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was used to rate the quality of evidences. RESULTS: Data from 18 studies involving 1,065 pediatric patients were acquired. The results revealed that use of sugammadex was associated with shorter duration from administration of reversal agents to TOFr > 0.9 (MD = -14.42, with 95% CI [-17.08, -11.75]) and shorter interval from reversal from NMB to extubation (MD = -13.98, with 95% CI [-16.70, -11.26]) compared to control groups. TSA also indicated that the current sample sizes were sufficient with unnecessary further trials. Analysis of secondary outcomes indicated that administration of sugammadex was associated with less incidence of postoperative nausea and vomiting (PONV), bradycardia, and dry mouth compared to control groups. CONCLUSION: Considering of satisfactory and rapid neuromuscular blockade reversal with low incidences of adverse events, sugammadex might be considered as the preferred option for children in clinical anesthesia practice compared to acetylcholinesterase inhibitors. However, overall low-quality evidences in present study rated by GRADE system indicated that superiority of sugammadex employed in pediatric patients needs to be confirmed by more studies with high quality and large sample size in future.

A comparison of sugammadex and neostigmine for reversal of rocuronium-induced neuromuscular blockade in children.

BACKGROUND: Sugammadex is designed to be a reversal agent for steroidal muscle relaxants. The current trial was aimed to compare between sugammadex and neostigmine concerning the recovery time from neuromuscular blockade. We hypothesised that sugammadex might have shorter recovery time than neostigmine. METHODS: Sixty paediatric patients aged 2-10 years scheduled for lower abdominal surgeries were randomly assigned into two equal groups to receive 4 mg/kg sugammadex (Group S) or 0.35 mg/kg neostigmine and 0.02 mg/kg atropine (Group N) as a reversal agent for rocuronium at the end of surgery. Primary outcome was the recovery time [time from starting of sugammadex or neostigmine till reaching train of four (TOF) ratio> 0.9] whereas secondary outcomes included number of patients who needed another dose of sugammadex or neostigmine to reach TOF ratio> 0.9, extubation time (time from stoppage of anaesthetic inhalation until the patient fulfilled criteria for safe extubation, post-anaesthesia care unit (PACU) discharge time and post-operative adverse effects. RESULTS: The mean recovery and extubation times were significantly shorter (P = 0.002 and 0.005) in Group S compared with Group N (2.5 and 2.0 min vs. 12.6 min and 4.3 min respectively). In the Group N, eight patients needed another reversal dose compared with one patient in Group S (P = 0.035). PACU discharge time showed no significant difference between both groups. Incidence of nausea, vomiting, tachycardia, and dry mouth were significantly higher in Group N. CONCLUSION: Sugammadex administration in children resulted in faster recovery and extubation times and lower incidence of adverse events compared with neostigmine.

Comparison of the trapezius and the adductor pollicis muscle as predictor of good intubating conditions: a randomized controlled trial.

BACKGROUND: Adequate muscle relaxation is important for ensuring optimal conditions for intubation. Although acceleromyography of the adductor pollicis muscle is commonly used to assess conditions for intubation, we hypothesized that acceleromyography of the trapezius is more indicative of optimal intubating conditions. The primary outcome was the difference between both measurement sites with regard to prediction of good or acceptable intubating conditions. METHODS: Neuromuscular blockade after injection of rocuronium 0.3 mg/kg IV was measured simultaneously with acceleromyography of the adductor pollicis muscle and the trapezius muscle in sixty female patients, American Society of Anesthesiologists physical status I to III, undergoing general anesthesia for gynecologic surgery. Exclusion criteria were: expected difficult tracheal intubation (e.g. history of difficult intubation, reduced mouth opening (< 2 cm) and/or Mallampati Score 4), increased risk of pulmonary aspiration (e.g. gastroesophageal reflux or delayed gastric emptying) allergies to drugs used during the study, pregnancy, neuromuscular diseases, medication with potential to influence neuromuscular function (e.g. furosemide, magnesium, cephalosporins) and hepatic or renal insufficiency (serum bilirubin >26 µmol/L, serum creatinine >90 µmol/l). Patients were randomized to 2 groups: group A (n = 30): endotracheal intubation after onset of the neuromuscular block at the adductor pollicis muscle. Group B (n = 30): endotracheal intubation after onset at the trapezius muscle. Intubating conditions were compared between both groups by means of a standardised score (the Copenhagen score) with Fisher's exact test. RESULTS: Onset of the block after rocuronium injection was observed at the adductor pollicis muscle compared to the trapezius with 2.8 (1.1) versus 2.5 (1.1) min (mean ± SD; P = 0.006). Intubating conditions were poor in 2 patients (7%) of group A, and in 1 patient (3%) of group T. They were acceptable (either excellent or good) in 28 patients (93%) in group A, and in 1 patient (97%) in group T (P = 0.82). CONCLUSIONS: Performing acceleromyography at the trapezius muscle reduced the time between injection of neuromuscular blocking agents and intubation by 18 s (11%). Thus, trapezius muscle acceleromyography is an acceptable alternative to adductor pollicis muscle acceleromyography in predicting acceptable intubating conditions, which allows for earlier indication of adequate intubating conditions. TRIAL REGISTRATION: ClinicalTrial.gov Identifier: NCT01849198 . Registered April 29, 2013.

Deep neuromuscular block improves the surgical conditions for laryngeal microsurgery.

BACKGROUND: Adequate neuromuscular block is required throughout laryngeal microsurgery. We hypothesized that the surgical conditions would improve under a deeper level of rocuronium-induced neuromuscular block. METHODS: Seventy-two patients undergoing laryngeal microsurgery were randomly allocated to either the 'post-tetanic counts 1-2' (PTC1-2) group or the 'train-of-four counts 1-2' (TOFcount1-2) group according to the level of neuromuscular block used. Two different doses of rocuronium (1.2 or 0.5 mg kg(-1)) were used after anaesthetic induction, and two respective targets of neuromuscular block (post-tetanic counts ≤2 or train-of-four count of 1 or 2) were used. Surgical conditions were assessed by the surgeon using a five-point rating scale (extremely poor/poor/acceptable/good/optimal), and clinically acceptable surgical conditions were defined as those which were rated acceptable, good, or optimal. The occurrence of vocal cord movement and postoperative adverse events was assessed. RESULTS: The surgical conditions were significantly different between the PTC1-2 and TOFcount1-2 groups (extremely poor/poor/acceptable/good/optimal: 0/2/1/7/26 and 3/10/2/14/7, respectively, P<0.001). The incidence of clinically acceptable surgical conditions was significantly higher in the PTC1-2 group than in the TOFcount1-2 group (94 vs 64%, P=0.003). The percentage of patients who exhibited vocal cord movement was significantly lower in the PTC1-2 group than in the TOFcount1-2 group (3 vs 39%, P<0.001). The incidence of postoperative adverse events was not significantly different except for the less frequent occurrence of mouth dryness in the PTC1-2 group (P=0.035). CONCLUSIONS: Deep neuromuscular block (post-tetanic count of 1-2) surgical conditions in patients undergoing laryngeal microsurgery improves. CLINICAL TRIAL REGISTRATION: NCT01980069.

[Effect of Preoperative Oral Rehydration on Onset Time and Recovery Time of Rocuronium].

BACKGROUND: Preoperative oral rehydration solution (ORS) prevents hypovolemia. The aim of this study was to compare the effect of intubating dose of rocuronium in patients taking and those not taking preoperative ORS. METHODS: Twenty patients, ASA I aged 20-50 years scheduled for elective surgery, were investigated and randomly assigned to two groups: drinking 1,500 ml ORS 6 to 2 hours before anesthesia (ORS group) and nothing by mouth from 6 hours before anesthesia (control group). Anesthesia was maintained with propofol and remifentanil, and rocuronium 0.6 mg x kg(-1) was administrated. To evaluate the effect of rocuronium, acceleromyography at the adductor pollicis was performed using 0.1 Hz stimulation. Cardiac index (CI) and stroke volume variation (SVV) from FloTra/Vigileo, times to 95% twitch depression as onset time (OT), and times to first twitch re-detection (TR) were recorded. RESULTS: SVV was significantly lower in ORS group (P = 0.03), and CI showed no difference. In ORS group, TR was significantly shorter than that of control group (P=0.002), and OT tended to be prolonged (99.0 ± 36.3 s vs. 84.0 ± 37.5 s), but not significantly. CONCLUSIONS: Preoperative oral rehydration possibly increases circulating blood volume, and shortens the duration of rocuronium effect.

Anesthetic considerations in Sheldon-Hall syndrome.

Arthrogryposis is characterized by multiple, nonprogressive joint contractures which may be caused by maternal disorders such as oligohydramnios as well as fetal akinesia resulting from primary disorders of muscle, connective tissue, or neurologic tissue. Its prevalence is about 1 : 3000. Distal arthrogryposis (DA) is a heterogenous group of genetic disorders with a characteristic flexion of the joints of the hands and feet divided into different types with additional features. Sheldon-Hall Syndrome (SHS), also known as distal arthrogryposis type 2A (DA2A), has some nonorthopedic features of specific importance to anesthetic care.

Acute angle-closure glaucoma after general anesthesia for bone grafting.

Acute angle-closure glaucoma (AACG) is a rare complication of general anesthesia. The coexistence of individual risk factors for postoperative AACG and factors associated with intraocular hypertension are considered to be required for postoperative AACG to develop. We present a case of AACG after general anesthesia for oral bone grafting in a patient with no preoperative eye symptoms. In this case, several factors such as postoperative care in a darkened room, psychological stress, and postoperative hypertension may have precipitated the event in this patient, who may have had preexisting undiagnosed elevated intraocular pressure. The interval between the earliest appearance of symptoms at 9 hours and the ultimate diagnosis was 36 hours. In the postoperative period following general anesthesia, any patient is at risk for AACG. It is important that a postoperative diagnosis of AACG should be considered and a timely consultation with an ophthalmologist be considered if a postoperative patient complains of red eyes, visual disorder, eye pain, headache, and nausea.

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.

High Le Fort I and bilateral split sagittal osteotomy in Crouzon syndrome.

Crouzon syndrome is a rare, autosomal dominant disease from a fibroblast growth factor receptor 2 gene mutation, characterized by premature craniosynostosis, hypertelorism, orbital proptosis, psittichorina, hypoplastic maxilla, and mandibular prognathism. We present an adult 32-year-old Crouzon syndrome patient who underwent an elective High Le Fort I and bilateral split sagittal osteotomy for midface advancement with a background of jaw malocclusion and obstructive respiratory symptoms. The operation features a potential dynamic movement of the secured airway in the surgical field and close proximity to exposed ocular structures. Permissive hypotensive anesthesia was employed to improve the surgical field and reduce intraoperative blood loss and dose of long-acting opioids. He was extubated at the end of an uneventful surgery and was monitored in the high dependency overnight before he was discharged to the general ward. Perioperative issues include potential difficult airway management; ocular, auditory, and neurological injury prevention; surgery-specific anesthetic technique; and postoperative analgesia. Understanding the multisystemic issues facilitates the dynamic anesthetic management during surgery. Good communication among the multidisciplinary team is essential to ensure a successful operation and uneventful recovery.

Sex-related differences in the relationship between acceleromyographic adductor pollicis train-of-four ratio and clinical manifestations of residual neuromuscular block: a study in healthy volunteers during near steady-state infusion of mivacurium.

BACKGROUND: Studies in volunteers suggest that train-of-four (TOF) ratios >0.9 are needed to retain normal function of muscles involved in upper airway patency, swallowing, and vital capacity breathing. We determined if sex-related differences exist in the relationship between adductor pollicis (AP) TOF ratio and measures of neuromuscular function commonly used to assess recovery from neuromuscular block. METHODS: In 10 males and 10 females, three steady-state levels of neuromuscular block were achieved with mivacurium infusions. TOF ratio was measured with acceleromyography at the AP. Hand grip strength and the ability to clench the teeth, raise the head >5 s, swallow, protrude the tongue, and open the eyes were tested at each stable block level and reconciled to uncorrected and normalized (pre-paralysis values) TOF measures. These relationships were compared between sexes. RESULTS: The ability to clench teeth and head raise >5 s was lost at a significantly greater TOF ratio in males than females. The percentage decrease in handgrip strength with decreasing TOF ratio was proportionally greater in males than females. Forty per cent of the males were unable to clench the teeth at an uncorrected TOF ratio >0.9. When TOF ratios were normalized, clinical functions showed no decrement at TOF ratio >0.9 in any volunteer. CONCLUSIONS: Sex-related differences exist in the relationship between AP TOF ratio and clinical measures of muscle function used to assess recovery from neuromuscular block. Normalization of AP TOF ratios is recommended because a non-normalized TOF ratio of 0.9 does not guarantee adequate reversal of neuromuscular block.

Oral mucosal injection of a local anesthetic solution containing epinephrine enhances muscle relaxant effects of rocuronium.

The purpose of this study was to examine how submucosal injection of a clinically relevant dose of a lidocaine hydrochloride solution containing epinephrine affects the muscle relaxant effects of rocuronium bromide. Sixteen patients scheduled for orthognathic surgery participated in this study. All patients were induced with fentanyl citrate, a target-controlled infusion of propofol and rocuronium bromide. Anesthesia was maintained by total intravenous anesthesia. After nasotracheal intubation, an infusion of rocuronium bromide was started at 7 µg/kg/min, and the infusion rate was then adjusted to maintain a train of four (TOF) ratio at 10 to 15%. The TOF ratio just prior to oral mucosal injection of a 1% lidocaine hydrochloride solution containing 10 µg/mL epinephrine (LE) was taken as the baseline. TOF ratio was observed for 20 minutes, with 1-minute intervals following the start of injection. Mean epinephrine dose was 85.6 ± 18.6 µg and mean infusion rate of rocuronium bromide was 6.3 ± 1.6 µg/kg/min. TOF ratio began to decrease 2 minutes after the injection of LE, reached the minimum value at 3.1 ± 3.6% 12 minutes after the injection, and then began to recover. We conclude that oral mucosal injection of LE enhances the muscle relaxant effects of rocuronium bromide.

Anesthetic considerations for masticatory muscle tendon-aponeurosis hyperplasia: a report of 24 cases.

Masticatory muscle tendon-aponeurosis hyperplasia (MMTAH) is a new disease entity characterized by limited mouth opening due to contracture of the masticatory muscles, resulting from hyperplasia of tendons and aponeuroses. In this case series, we report what methods of airway establishment were conclusively chosen after rapid induction of anesthesia. We had 24 consecutive patients with MMTAH who underwent surgical release of its contracture under general anesthesia. Rapid induction of anesthesia with propofol and rocuronium was chosen for all the cases. In 7 cases, intubation using the Macintosh laryngoscopy was attempted; however, 2 of those cases failed to be intubated on the first attempt. Finally, intubation using the McCoy laryngoscopy or fiber-optic intubation was alternatively used in these 2 cases. In 7 cases, the Trachlight was used. In the remaining 10 cases, fiber-optic intubation was used. Limited mouth opening in patients with MMTAH did not improve with muscular relaxation. "Square mandible" has been reported to be one of the clinical features in this disease; however, half of these 24 patients lacked this characteristic, which might affect a definitive diagnosis of this disease for anesthesiologists. An airway problem in patients with MMTAH should not be underestimated, which means that other intubation methods rather than direct laryngoscopy had better be considered.

Administration of general anesthesia for outpatient orthognathic surgical procedures.

The administration of anesthesia has shifted away from the traditional hospital setting to an enormous increase in the use of outpatient facilities. The development of short-acting anesthetics, advances in surgical techniques, and paradigm shifts accepting targeted hospital admission and preoperative testing have allowed the acceptance of outpatient anesthesia for a wide variety of surgical procedures, including orthognathic procedures. Furthermore, the cost savings associated with office-based surgery and the declining insurance coverage for procedures such as orthognathic surgery have helped to increase the demand for surgery in this setting. The administration of anesthesia for orthognathic surgery in an outpatient setting requires preoperative preparation, preoperative patient assessment and selection, use of short-acting anesthetic agents and techniques, presence of emergency drugs and equipment, appropriate recovery protocols and staff, and the presence of adequate caregivers upon home discharge. Anesthetic techniques and agents allowing multiple orthognathic procedures to be performed in the outpatient setting are described.

Relationship between normalized adductor pollicis train-of-four ratio and manifestations of residual neuromuscular block: a study using acceleromyography during near steady-state concentrations of mivacurium.

BACKGROUND: Baseline acceleromyographic adductor pollicis train-of-four (TOF) ratio varies significantly between individuals and is often greater than unity. Thus, normalization of acceleromyography data is necessary. The relationship between normalized acceleromyographic TOF ratio, lung volumes, and clinical signs of residual neuromuscular block was studied. METHODS: In 12 healthy volunteers, three steady-state levels of neuromuscular block were achieved with mivacurium infusions. TOF ratio was measured acceleromyographically at the adductor pollicis using a preload. Lung volume measurements and a series of clinical tests were made at each stable block and reconciled to the normalized TOF measures. RESULTS: None experienced airway obstruction or arterial oxygen desaturation, even at normalized TOF ratio less than 0.4. Functional residual capacity remained unchanged whereas vital capacity decreased linearly with decreasing TOF ratio. The ability to protrude the tongue was preserved at all times. The ability to clench the teeth was lost in one volunteer at normalized TOF ratio of 0.84 but retained in four at normalized TOF ratio less than 0.4. Four volunteers lost the ability both to raise the head more than 5 s and to swallow, with the most sensitive individual demonstrating these effects at normalized TOF ratio of 0.60. At mean normalized TOF ratio of 0.42, the mean handgrip strength was approximately 20% of baseline value. CONCLUSION: Lung vital capacity decreased linearly with decreasing TOF ratio. Responses to clinical tests of muscle function varied to a large extent among individuals at comparable TOF ratios. None of the volunteers had significant clinical effects of neuromuscular block at normalized acceleromyographic TOF ratio greater than 0.90.

Rocuronium and vecuronium do not affect mandibular bone marrow and masseter muscular blood flow in rabbits.

PURPOSE: The goal of this study was to investigate the effect of rocuronium and vecuronium continuous infusion on oral tissue blood flow in rabbits. MATERIALS AND METHODS: We used 8 male Japan White rabbits. The infusion rates of rocuronium were 7, 14, and 28 microg kg(-1) min(-1) for 20 minutes, in this order. After rocuronium was discontinued and body movement confirmed, continuous infusion of vecuronium was started. The infusion rates of vecuronium were 1.6, 3.2, and 6.4 microg kg(-1) min(-1) for 20 minutes, in this order. Observed variables were systolic blood pressure, diastolic blood pressure, mean arterial pressure, heart rate, common carotid artery blood flow, tongue mucosal blood flow, oxygen partial pressure of the mandibular bone marrow, and oxygen partial pressure of the masseter muscle. RESULTS: Heart rate in both groups tended to decrease depending on the infusion rate. Common carotid artery blood flow in the rocuronium group was increased depending on the infusion rate. Tongue mucosal blood flow in the vecuronium group was decreased depending on the infusion rate. There were no differences in diastolic blood pressure, mean arterial pressure, oxygen partial pressure of the mandibular bone marrow, and oxygen partial pressure of the masseter muscle between the 2 groups. Systolic blood pressure in both groups showed no major change. CONCLUSION: Rocuronium and vecuronium did not change mandibular bone marrow and masseter muscular blood flows. Vecuronium decreased tongue mucosal blood flow depending on the infusion rate.

Monitoring masseter muscle evoked responses enables faster tracheal intubation.

PURPOSE: The aim of this study was to investigate whether monitoring neuromuscular block at the masseter muscle (MM) would allow faster tracheal intubation when compared with that at the adductor pollicis muscle (APM). METHODS: Twenty female patients undergoing gynecological surgery were enrolled into this study. Immediately after inducing anesthesia with fentanyl and propofol, both the left masseter and ulnar nerves were stimulated in a 2 Hz train-of-four (TOF) mode using peripheral nerve stimulators. Contractions of the MM were felt with the anesthesiologist's left hand lifting the patient's jaw and holding an anesthesia facemask, while those of the APM were visually observed. Immediately after the contracting responses of the muscles were confirmed, all of the patients received an iv bolus of vecuronium 0.1 mg kg(-1). Onset times after vecuronium were defined as the duration until the contractions became impalpable at the MM or invisible at the APM. When the contraction of the MM could no longer be felt, the conditions for laryngoscopy and tracheal intubation were assessed. RESULTS: Onset time evaluated tactually at the MM (mean +/- SD, 108.4 +/- 27.7 s) was significantly shorter than that evaluated visually at the APM (181.2 +/- 32.1 s, P < 0.0001). The intubating conditions for all patients were graded as either excellent or good. CONCLUSION: Tactual evaluation of muscle paralysis of the MM during induction of anesthesia is clinically useful since it leads to faster tracheal intubation.

[Tracheal intubation quality under remifentanil-propofol with sevoflurane compared with remifentanil-propofol with rocuronium: a randomized double-blind clinical trial]. / Evaluación clínica de la calidad de la intubación endotraqueal con remifentanilo-propofol-sevoflurano comparada con remifentanilo-propofol-rocuronio: ensayo clínico aleatorizado, doble ciego.

OBJECTIVE: To determine whether intubation conditions under remifentanil-propofol plus sevoflurane rather than a nondepolarizing neuromuscular blocker are similar to those obtained when a neuromuscular blocker is used. MATERIAL AND METHODS: In this double-blind controlled trial, 100 patients undergoing outpatient surgery were randomized to 2 groups. Intubation in one group was performed under remifentanil, propofol and sevoflurane. In the other, intubation was performed under remifentanil, propofol, and the nondepolarizing neuromuscular blocker rocuronium. We recorded dysphonia at 24 hours, Cormack-Lehane classification at laryngoscopy, mandibular relaxation, vocal cord position and mobility, and cough or movement during laryngoscopy, on intubation and on cuff inflation. Blood pressure and heart rate before and after tracheal intubation were also recorded. RESULTS: No significant between-group differences were observed in dysphonia 24 hours after surgery, Cormack-Lehane classification at laryngoscopy, mandibular relaxation, the position or mobility of vocal cords, or cough or movement during laryngoscopy, intubation or cuff inflation. After intubation the mean (SD) systolic blood pressure was 119.7 (75.4) mm Hg in the rocuronium group and 97.5 (54.5) mm Hg in the sevoflurane group. Mean heart rate was 80.7 beats/min in the rocuronium group and 66.7 beats/min in the sevoflurane group. The differences were significant (P < .05). CONCLUSIONS: Adequate doses of remifentanil, propofol, and sevoflurane provide intubation conditions that are similar to those achieved by using a nondepolarizing neuromuscular blocker, without exposing patients to additional risk. Avoiding use of a neuromuscular blocker would circumvent the development of complications associated with use of these agents or their antagonists and costs would be lower.

Association between factors predicting and assessing the airway and use of intubating laryngeal mask airway.

BACKGROUND AND OBJECTIVE: The Intubating Laryngeal Mask Airway FastrachTM (ILMA) has been used with success in difficult intubation cases. The purpose of this study is to evaluate the effect of mouth opening, Mallampati classification, thyromental distance and Cormack-Lehane Grade, on the ease of ILMA use. METHODS: Eighty one patients ASA I-II, were assessed preoperatively for mouth opening, Mallampati classification and thyromental distance. After induction with propofol and rocuronium, the first investigator recorded Cormack-Lehane Grade by direct laryngoscopy. Subsequently an appropriate size ILMAwas inserted by the second investigator and correct placement was confirmed by adequate ventilation and normal capnogram. A maximum of three ILMA insertion attempts were allowed and the number was recorded. Then blind intubation was attempted and classified as follows, according to Intubation Difficulty Grade (IDG): IDG-1: intubation succeeded: at first attempt requiring no or minor ILMA manipulations. IDG-2: intubation succeeded at second attempt requiring major ILMA manipulations or size change. IDG-3: intubation failed after the second attempt or oesophageal intubation occurred at either attempt. In failure of the technique direct laryngoscopy was the alternative approach. RESULTS: Success rates in insertion of ILMA and in blind intubation were 100% and 92.6% respectively. No difference was found between Cormack-Lehane Grade I-II and II-IV or Mallampati classification and number of ILMA insertion attempts or IDG. There was also no correlation between mouth opening, or thyromental distance and number of ILMA insertion attempts or IDG. It is concluded that easiness of ILMA use is irrelevant to mouth opening, thyromental distance, Mallampati classification or Cormack-Lehane Grade.

Comparison of intubation condition and the quality of muscle relaxation between rocuronium and vecuronium using "timing principle".

Aim To compare the quality of the conditions for endotracheal intubation and muscle relaxation between rocuronium bromide and vecuronium bromide using the ''timing principle'' method for induction in anaesthesia. The "timing principle" includes the administration of muscle relaxants before the hypnotic agent during induction in anaesthesia. Method Sixty patients who had undergone elective surgery were randomly allocated into two equal groups using muscle relaxants: rocuronium (group R) and vecuronium (group V). The intubation conditions were assessed using Cooper's scoring system, based on jaw relaxation, vocal cords position and response to intubation. The quality of muscle relaxation was evaluated by recording the time of clinical weakness, a count of ''train of four'' (TOF) twitches at intubation, the time of loss TOF response and duration of direct laryngoscopy. Results The intubation conditions were excellent in 100% of patients in the group R versus excellent in 80% and good in 20% of patients in the group V (p<0.05). The time of clinical weakness was statistically significantly shorter in the group R than in the group V (p<0.000). The time of loss of TOF response was statistically significantly shorter in the group R (p<0.000). The absence of TOF twitches (the level of muscle relaxation of 100%) at intubation recorded in 25 (83.3%) patients in the group R versus five (16.7%) patients in the group V (p<0.000). Duration of direct laryngoscopy did not significantly differ between the groups. Conclusion Rocuronium bromide provides better intubation conditions and greater quality of muscle relaxation than vecuronium bromide using ''timing principle'' technique.