Residual neuromuscular block as a risk factor for critical respiratory events in the post anesthesia care unit

OBJECTIVE

Residual neuromuscular block is an important postoperative complication associated to the use of neuromuscular blocking drugs. The purpose of this study was to access the incidence of residual neuromuscular block in a post-anesthesia care unit and to evaluate its association with critical respiratory events.

MATERIAL AND METHODS

Prospective cohort study was conducted in a Post Anesthetic Care Unit (PACU) for a period of 3 weeks. Two hundred two adult patients who submitted to scheduled non-cardiac and non-intracranial surgery were eligible to the study. The primary outcome variable was residual neuromuscular block after arrival to PACU that was defined as train-of-four ratio <0.9 and objectively quantified using acceleromyography. Demographic data, perioperative variables, lengths of hospital and recovery room stay and critical respiratory events were recorded. Inadequate emergence was classified in its different forms according to the Richmond agitation and sedation scale 10 min after admission to the recovery room.

RESULTS

Residual neuromuscular block incidence in the post-anesthesia care unit was 29.7% (95% confidence interval: 23.4, 36.1). Patients with residual neuromuscular block had more frequently overall critical respiratory events (51% versus 16%, P<0.001), airway obstruction (10% versus 2%, P=0.029), mild-moderate hypoxemia (23% versus 4%, P<0.001), severe hypoxemia (7% versus 1%, P=0.033), respiratory failure (8% versus 1%, P=0.031), inability to breathe deeply (38% versus 12%, P<0.001) and muscular weakness (16% versus 1%, P<0.001). Residual neuromuscular block was more common after high-risk surgery (53% versus 33%, P=0.011) and was more often associated with post-operative hypoactive emergence as defined by the Richmond Agitation and Sedation Scale (21% versus 6%, P=0.001).

CONCLUSIONS

This study suggests that residual neuromuscular block is common in the PACU and is associated with more frequent critical respiratory events.

[Peripheric blockades in plastic and reconstructive surgery: up-to-date trends and prospects (a 30-year experience)]

The article presents the own 30-year experience in the use of more than 1000 prolonged peripheral nerves and plexus block anaesthesia in reconstructive surgery, based on experimental and clinical studies. The evolution peripheric blockades technique is given:from a separate anaesthesia method to balanced anesthesia based on peripheric blockades. The current state of the problem was analyzed according to the literature.

Optimized surgical space during low-pressure laparoscopy with deep neuromuscular blockade

INTRODUCTION

Laparoscopic cholecystectomy (LC) can be performed using low intra-abdominal pressure (< 12 mmHg), but surgical conditions may not be optimal. The present study aimed at comparing surgical space conditions using either deep, continuous muscle relaxation or moderate blockade during low-pressure (8 mmHg) LC. We hypothesized that a deep neuromuscular block would be associated with a higher proportion of optimal surgical space conditions.

MATERIAL AND METHODS

This was an investigator-initiated, patient- and assessor-blinded study. Up to 72 patients scheduled for elective LC were randomised to either deep neuromuscular blockade (post-tetanic count 0-1) or moderate neuromuscular blockade, where at least one response to train-of-four nerve stimulation was present. The primary outcome was surgical space conditions at the time during surgery when conditions were worst. The secondary outcomes included the proportion of procedures completed at pneumoperitoneum 8 mmHg, post-operative pain, and incidence of nausea and vomiting.

RESULTS

This study was the first randomised study to assess the association between depth of neuromuscular blockade and surgical space conditions during low-pressure LC. The study findings may be applicable to a general surgical population undergoing LC.

FUNDING

The University of Copenhagen, Denmark and Sophus Johansens Foundation of 1981, Denmark funded this study, which was also financed by a research grant from the Investigator Initiated Studies Program of Merck Sharp and Dohme Corp.

TRIAL REGISTRATION

NCT 01523886.

[Modern approach to the neuromuscular blocking agents use in pediatric patients]

Myorelaxants use decrease trend appeared since the end of 80 years of the 20th century. The trend is connected with use of the new narcotic analgesics (Remifentanil), intravenous (Propofol) and inhalation (Sevoflurane) anaesthetics. These drugs are manageable and predictable, they have not many side effects and can suppress laryngeal-pharyngeal reflex during the tracheal intubation. Furthermore there are other factors such as succinylcholines use when fast intubation is needed, the wrong myorelaxant and dosage choice. Residual curarization and side effects risk increases due to these factors. As a result the patient's activation is delayed. Nevertheless myorelaxants use refusal impairs the tracheal intubation conditions, increases the arterial hypotension and heart failure risk especially in newborns and children with severe pathology. If myorelaxants is not used, comfortable conditions of surgical manipulations impossible without big analgesics and anaesthetics doses use.

[Prolonged residual paralysis after a single intubating dose of rocuronium: an unexpected cause]

Postoperative curarization following a single dose of rocuronium is a known risk quickly diagnosed through the monitoring of neuromuscular blockade. Different etiologies can cause a prolonged block. We report the case of a misdiagnosis of prolonged neuromuscular blockade by a failure in the monitoring system of curarization.

[Extremely prolonged neuromuscular block after a single dose of rocuronium]

Postoperative curarization in patients has been established. Nevertheless, extremely prolonged neuromuscular blockades are rare. We report the case of a prolonged neuromuscular blockade (lasting 10 hours) following a single dose of rocuronium, in an elderly patient with severe renal failure. We have studied the possible causes of prolonged curarization, and discussed the interest of the use of sugammadex in such cases.

[Congenital pseudocholinesterase deficiency]

BACKGROUND

Congenital pseudocholinesterase (pChe) deficiency is a rare genetic abnormality which may lead to prolonged duration of action of muscle relaxants that are hydrolysed by pChe. We describe two cases in which mivacurium resulted in neuromuscular block lasting several hours.

CASE REPORTS

Two non-related male patients, aged 26 and 7 years, scheduled for elective ENT surgery, received propofol, desflurane, remifentanil and mivacurium. At the end of the surgery it was not possible to reverse the neuromuscular blockade, and there were no responses to TOF or post-tetanic stimulation. Neuromuscular transmission returned spontaneously after 7, and 4 h, respectively. Postoperative assay revealed severe pChe deficiency in both patients, with values of 3393 UL(-1)and 2558 UL(-1), respectively (normal range 5100-11700 UL(-1). Family screening confirmed the presence of pChe deficiency in both cases.

CONCLUSION

In any case of unexpected prolonged muscle relaxation after mivacurium, pChe deficiency should be considered and its activity measured.When confirmed, careful family screening is mandatory.

Knowledge of residual curarization: an Italian survey

BACKGROUND

The use of neuromuscular blocking agents (NMBAs) is widespread in anesthetic practice; little is known about the current use of these drugs in Italy. This survey was conducted to obtain information about the most commonly used clinical tests and the train-of-four (TOF) ratios that are considered as being reliable for assessing recovery from neuromuscular blockade at the end of anesthesia and the estimated occurrence rates of post-operative paralysis in Italian hospitals.

METHODS

The questionnaire was given to Italian anesthesiologists attending the 62nd National Congress of the Italian Society of Anesthesia, Analgesia and Intensive Therapy. Collected data were stratified by age and the total number of surgical procedures performed in the hospitals concerned.

RESULTS

Seven hundred and fifty-four correctly compiled questionnaires were collected (response rate 88.7%). Seventy three percent of the respondents only used clinical tests for monitoring the level of neuromuscular blockade. The main clinical tests cited for the evaluation of residual paralysis were keeping the head lifted up for 5 s, protruding the tongue and opening the eyes. TOF was used by 35% of the respondents on a routine basis. Only 24% of the interviewed anesthesiologists reported that before extubation, a TOF ratio of at least 0.9 should be reached.

CONCLUSIONS

Most Italian anesthetists assess the recovery from neuromuscular blockade only by clinical signs. There is poor awareness about the inability of such techniques to indicate even a significant amount of residual neuromuscular block. A more extensive use of quantitative instrumental monitoring is required for the more rational use of NMBAs.

A new approach to anesthesia management in myasthenia gravis: reversal of neuromuscular blockade by sugammadex

A neuromuscular blocking drug (NMBD) induced neuromuscular blockade (NMB) in patients with myasthenia gravis usually dissipates either spontaneously or by administration of neostigmine. We administered sugammadex to a patient with myasthenia gravis to reverse a rocuronium-induced profound NMB. NMBDs predispose such patients to severe postoperative residual paralysis and respiratory complications. Sugammadex binds steroidal NMBDs and, therefore reverses a rocuronium or vecuronium-induced NMB, without interfering with cholinergic transmission. A rapid and complete recovery from profound NMB was achieved and no adverse events were observed. This case suggests that sugammadex is a safe and effective antagonist of a rocuronium induced NMB blockade in patients with myasthenia gravis.

[Neuromuscular blockade monitoring. Part 1]

Many recent studies have underlined the importance of quantitative neuromuscular monitoring and the high incidence of residual block in clinical practice in spite of the use of nondepolarizing neuromuscular blockers of intermediate duration. Neuromuscular monitoring facilitates the tailoring of the muscular paralysis and appropriate patient recovery at the end of surgery. Monitoring also controls or prevents residual block and serves to guide the use of reversing agents. This review describes the physiology of neuromuscular junctions as well as the principles and patterns of nerve stimulation and clinical monitoring. In addition to drawing on their own experience, the authors have reviewed the literature available through evidence-based indexes and other databases up to December 2008. Most references found were case series and reviews. Quantitative monitoring is an evidence-based practice that should be applied in all situations in which a neuromuscular block is established.

Time course of rocuronium-induced neuromuscular block after pre-treatment with magnesium sulphate: a randomised study

BACKGROUND

A previously published study suggested that pre-treatment with magnesium sulphate (MgSO(4)) had no impact on the speed of onset of rocuronium-induced neuromuscular block. We set out to verify this assumption.

METHODS

Eighty patients (18-60 years) were randomly allocated to MgSO(4) 60 mg/kg or placebo (saline). Study drugs were given intravenously for 15 min before induction of anaesthesia with propofol, sufentanil and rocuronium 0.6 mg/kg. Anaesthesia was maintained with a target-controlled propofol infusion. Neuromuscular transmission was measured using train-of-four (TOF)-Watch SX acceleromyography.

RESULTS

Onset was analysed in 37 MgSO(4) and 38 saline patients, and recovery in 35 MgSO(4) and 37 saline patients. Onset time (to 95% depression of T1) was on average 77 [SD=18] s with MgSO(4) and 120 [48] s with saline (P<0.001). The total recovery time (DurTOF0.9) was on average 73.2 [22] min with MgSO(4) and 57.8 [14.2] min with saline (P<0.003). The clinical duration (Dur25%) was on average 44.7 [14] min with MgSO(4) and 33.2 [8.1] min with saline (P<0.0002). The recovery index (Dur25-75%) was on average 14.0 [6] min with MgSO(4) and 11.2 [5.2] min with saline (P<0.02). The recovery time (Dur25%TOF0.9) was on average 28.5 [11.7] min with MgSO(4) and 24.7 [8.4] min with saline (P=0.28).

CONCLUSION

Magnesium sulphate given 15 min before propofol anaesthesia reduces the onset time of rocuronium by about 35% and prolongs the total recovery time by about 25%.

[Sugammadex, a novel drug for neuromuscular blockade reversal]

Significant progress in the management of aminosteroid nondepolarizing neuromuscular blockers will follow the introduction of sugammadex (Org 25969). Safety and rapid recovery of muscle force will improve and the adverse effects of acetylcholinesterase inhibitors will be avoided. Sugammadex is a modified gamma-cyclodextrin agent developed for the specific reversal of rocuronium and, to a lesser extent, vecuronium. This novel drug functions by means of encapsulation (chelation). Sugammadex was recently approved by the European Medicines Evaluation Agency and became available in Spain in 2009, leading to a series of changes related to patient safety and surgical conditions. We review the literature on sugammadex published to date.

Reduction in deep vein thrombosis incidence in intensive care after a clinician education program

BACKGROUND

Deep vein thrombosis (DVT) is a major complication in intensive care units (ICU) but dedicated guidelines on its management are still lacking.

OBJECTIVES AND METHODS

This study investigated the effect of a 1-year educational program for the implementation of DVT prophylaxis on the incidence of inferior limb DVT in a mixed-bed ICU that admits high-risk surgical and trauma patients, investigated during a first retrospective phase [126 patients, SAPS II score 42 (28-54)] and a following prospective phase [264 patients, SAPS II score II 41 (27-55)]. The role of baseline and time-dependent DVT risk factors in DVT occurrence was also investigated during the prospective phase.

RESULTS

The educational program on implementation of DVT prophylaxis was associated with a significant decrease in DVT incidence from 11.9% to 4.5% (P < 0.01) and in the mean length of ICU stay (P < 0.01). Combined with pharmacological prophylaxis, the use of elastic compressive stockings significantly also increased in the prospective phase (P < 0.01). The duration of mechanical ventilation, vasopressor administration and neuromuscular block were significantly different between DVT-positive and DVT-negative patients (P < 0.01). Multivariate analysis identified neuromuscular block as the strongest independent predictor for DVT incidence.

CONCLUSION

One-year ICU-based educational programs on implementation of DVT prophylaxis were associated with a significant decrease in the incidence of DVT and also in the length of stay in ICU.

[Efficacy of sugammadex in the reversal of neuromuscular blockade induced by rocuronium in long-duration surgery: under inhaled vs. intravenous anesthesia]

BACKGROUND AND OBJECTIVE

Sugammadex reverses neuromuscular blockade induced by aminosteroid agents by encapsulating these agents. The objective of this study was to compare the efficacy and safety of sugammadex to reverse a rocuronium-induced neuromuscular blockade in long-duration surgery in association with inhaled or intravenous anesthesia.

PATIENTS AND METHODS

We performed a randomized, double-blind, multicenter trial of 20 ASA 1-3 patients aged between 18 and 69 years and scheduled for elective surgery lasting at least 120 minutes. Anesthesia was induced with remifentanil and rocuronium at a dosage of 0.6 mg x kg(-1), and neuromuscular function was monitored by means of acceleromyography. After randomization, anesthesia was maintained with sevoflurane or with propofol for total intravenous anesthesia. Patients in both groups also received an infusion of remifentanil for analgesia and rocuronium to maintain a block of greater than 90%. After surgery, sugammadex was administered at a dosage of 2 mg x kg(-1) on reappearance of the second train-of-four (TOF) twitch (T2) and the times until recovery of T4/T1 ratios of 0.7, 0.8, and 0.9 (main endpoints). Mean arterial pressure and heart rate were recorded at baseline and after 2, 5, 10, and 30 minutes (secondary outcome measures).

RESULTS

Although less rocuronium was consumed in the sevoflurane group than in the propofol group and the time between the start of sugammadex administration until recovery of a TOF ratio of 0.9 was shorter for the sevoflurane group than for propofol group (mean [SD], 1.46 [0.30] minutes and 1.89 [0.62] minutes, respectively), these differences were not significant. No signs of recurarization or associated adverse effects were observed.

CONCLUSIONS

Sugammadex effectively and safely reverses a rocuronium-induced neuromuscular blockade in less than 2 minutes in long-duration surgery performed under both inhaled and intravenous anesthesia. The interaction of neuromuscular blocking agents with sevoflurane appears not to affect the reversal time of sugammadex in such operations.