Predictors of the variability in neuromuscular block duration following succinylcholine: A prospective, observational study.

BACKGROUND: The duration of neuromuscular block (NMB) following succinylcholine administration is characterised by a high interindividual variability. However, this has not yet been quantified in a large sample of surgical patients. The significance of underlying clinical factors is unknown. OBJECTIVE: The objective of this study was to profile the variability in NMB duration following a standard dose of succinylcholine and to investigate contributing clinical and genetic factors. DESIGN: A prospective, observational study. SETTING: Tertiary referral centre. PATIENTS: In a total of 1630 surgical patients undergoing a rapid sequence induction and intubation, clinical risk factors for a prolongation in NMB duration following succinylcholine were assessed. In a subset of 202 patients, additional biochemical and molecular genetic investigations of butyrylcholinesterase were performed. INTERVENTION: A standard 1 mg kg dose of succinylcholine after administration of an induction drug and an opioid. MAIN OUTCOME: NMB duration measured as the time between administration of succinylcholine until reappearance of palpable muscular response to supramaximal transcutaneous ulnar nerve stimulation. RESULTS: NMB varied from 80 s to 44 min with a median duration of 7.3 min. Sixteen percent of patients had NMB duration in excess of 10 min. A multivariable survival model identified physical status, sex, age, hepatic disease, pregnancy, history of cancer and use of etomidate or metoclopramide as independent risk factors for a prolonged NMB. Three novel butyrylcholinesterase variants were identified: p.Ile5Thr; p.Val178Ile; and p.Try231Ser. CONCLUSION: Neuromuscular blockade duration in excess of 10 min occurred in 16% of a general surgical population following a single dose of succinylcholine. The multivariable model of clinical risk factors for prolonged NMB revealed a negative predictive value of 87%, thereby indicating that absence of such risk factors may reliably predict a shorter duration of NMB. In patients with clinical risk factors for a prolonged NMB or with butyrylcholinesterase mutations, an alternative to succinylcholine should be considered.

Spinal anesthesia revisited: toxicity of new and old drugs and compounds.

PURPOSE OF REVIEW: Neural toxicity of substances injected into the intrathecal space has been a matter of debate since the introduction of spinal anesthesia in clinical practice. In recent years, new local anesthetics and adjuvants have been proposed for intrathecal use, and new techniques such as the use of ultrasound have been propagated. The present review summarizes recent clinical and experimental data on the neurotoxic effects of drugs and substances used for or in conjunction with spinal anesthesia. RECENT FINDINGS: Chloroprocaine has been demonstrated to be associated with a lower risk of transient neurologic symptoms compared with lidocaine. However, despite extensive research, the issue of chloroprocaine or bisulfite neurotoxicity has not yet been resolved.Recent experimental data have identified a smaller neurotoxic potential for ropivacaine compared to levobupivacaine, procaine and bupivacaine. The addition of epinephrine has not been shown to increase lidocaine neurotoxicity. In-vivo experimental data suggest that lidocaine and bupivacaine neurotoxicity is not enhanced in diabetic patients.Furthermore, intrathecal introduction of aqueous ultrasound gel has been demonstrated to cause a distinct neuroinflammatory reaction. Finally, a large cohort study did not find the use of chlorhexidine gluconate for skin disinfection before neuraxial block to be associated with the risk of adhesive arachnoiditis. SUMMARY: Clinical data suggest a high safety profile for intrathecal drugs and substances used for or in conjunction with spinal anesthesia. Recent experimental models for toxicity have provided further insight into the mechanisms and demonstrated possible, albeit clinically small differences in the relative neurotoxic potential of intrathecal drugs. This may contribute to a further increase in the safe use of spinal anesthesia in the clinical setting.

Speed spinal anesthesia revisited: new drugs and their clinical effects.

PURPOSE OF REVIEW: Spinal anesthesia (SPA) has not been popular for day-case surgery because of prolonged neurologic blockade with long-acting local anesthetics such as bupivacaine, thereby delaying discharge. Although the intermediate duration of action of lidocaine and mepivacaine appears to be more suitable for day-case surgery, their use is not deemed appropriate by many because of a high incidence of transient neurologic symptoms (TNSs). The present review summarizes recent clinical data on the intrathecal use of alternative local anesthetics and adjuvants that may offer valuable alternatives to general anesthesia in day-case surgery. RECENT FINDINGS: Prilocaine has a similar intrathecal pharmacokinetic profile as lidocaine but with a significantly lower risk of TNSs. Onset of spinal after 2-chloroprocaine is comparable with lidocaine or prilocaine, but with a considerably shorter duration of action. Also, TNS is clearly less frequent compared with lidocaine. Although its intrathecal use has recently been approved in Europe, this is still considered to be off-label in the USA. Articaine provides an extraordinary fast onset and a short duration of spinal block, the latter being approximately intermediate between chloroprocaine and prilocaine. However, articaine is associated with a high risk for intraoperative hypotension and a small risk for TNS, albeit but less frequent than after lidocaine. Concerns regarding possible neurotoxicity of articaine remain to be resolved. SUMMARY: SPA for day cases might become a most valuable method for ambulatory surgery when using short acting local anesthetics. This, however, not only depends on drugs being used but also on infrastructure (post anaesthesia care unit) and organizational issues.