Hossam El-Beheiry

Neurological complications after regional anesthesia: contemporary estimates of risk.

BACKGROUND:Regional anesthesia (RA) provides excellent anesthesia and analgesia for many surgical procedures. Anesthesiologists and patients must understand the risks in addition to the benefits of RA to make an informed choice of anesthetic technique. Many studies that have investigated neurological complications after RA are dated, and do not reflect the increasing indications and applications of RA nor the advances in training and techniques. In this brief narrative review we collate the contemporary investigations of neurological complications after the most common RA techniques. METHODS:We reviewed all 32 studies published between January 1, 1995 and December 31, 2005 where the primary intent was to investigate neurological complications of RA. RESULTS:The sample size of the studies that investigated neurological complications after central and peripheral (PNB) nerve blockade ranged from 4185 to 1,260,000 and 20 to 10,309 blocks, respectively. The rate of neuropathy after spinal and epidural anesthesia was 3.78:10,000 (95% CI: 1.06–13.50:10,000) and 2.19:10,000 (95% CI: 0.88–5.44:10,000), respectively. For common PNB techniques, the rate of neuropathy after interscalene brachial plexus block, axillary brachial plexus block, and femoral nerve block was 2.84:100 (95% CI 1.33–5.98:100), 1.48:100 (95% CI: 0.52–4.11:100), and 0.34:100 (95% CI: 0.04–2.81:100), respectively. The rate of permanent neurological injury after spinal and epidural anesthesia ranged from 0–4.2:10,000 and 0–7.6:10,000, respectively. Only one case of permanent neuropathy was reported among 16 studies of neurological complications after PNB. CONCLUSIONS:Our review suggests that the rate of neurological complications after central nerve blockade is <4:10,000, or 0.04%. The rate of neuropathy after PNB is <3:100, or 3%. However, permanent neurological injury after RA is rare in contemporary anesthetic practice.

Can Ultrasound of the Tibial Nerve Detect Diabetic Peripheral Neuropathy?: A cross-sectional study

OBJECTIVE Peripheral nerve imaging by portable ultrasound (US) may serve as a noninvasive and lower-cost alternative to nerve conduction studies (NCS) for diagnosis and staging of diabetic sensorimotor polyneuropathy (DSP). We aimed to examine the association between the size of the posterior tibial nerve (PTN) and the presence and severity of DSP. RESEARCH DESIGN AND METHODS We performed a cross-sectional study of 98 consecutive diabetic patients classified by NCS as subjects with DSP or control subjects. Severity was determined using the Toronto Clinical Neuropathy Score. A masked expert sonographer measured the cross-sectional area (CSA) of the PTN at 1, 3, and 5 cm proximal to the medial malleolus. RESULTS Fifty-five patients had DSP. The mean CSA of the PTN in DSP compared with control subjects at distances of 1 (23.03 vs. 17.72 mm2; P = 0.004), 3 (22.59 vs. 17.69 mm2; P < 0.0001), and 5 cm (22.05 vs. 17.25 mm2; P = 0.0005) proximal to the medial malleolus was significantly larger. Although the area under the curve (AUC) for CSA measurements at all three anatomical levels was similar, the CSA measured at 3 cm above the medial malleolus had an optimal threshold value for identification of DSP (19.01 mm2) with a sensitivity of 0.69 and a specificity of 0.77 by AUC analysis. CONCLUSIONS This large study of diabetic patients confirms that the CSA of the PTN is larger in patients with DSP than in control subjects, and US is a promising point-of-care screening tool for DSP.

Calcium chelation improves spatial learning and synaptic plasticity in aged rats

Impaired regulation of intracellular calcium is thought to adversely affect synaptic plasticity and cognition in the aged brain. Comparing young (2-3 months) and aged (23-26 months) Fisher 344 rats, stratum radiatum-evoked CA1 field EPSPs were smaller and long-term potentiation (LTP) was diminished in aged hippocampal slices. Resting calcium, in presynaptic axonal terminals in the CA1 stratum radiatum area, was elevated in aged slices. Loading the slice with the calcium chelator, BAPTA-AM, depressed LTP in young slices, but enhanced this plasticity in old slices. Forty-five minutes following LTP-inducing high frequency stimulation, resting calcium levels were significantly increased in both young and old presynaptic terminals, and significantly reduced by pretreatment with BAPTA-AM. In vivo, intraperitoneal administration of BAPTA-AM prior to training in the reference memory version of the Morris water maze test, significantly improved the acquisition of spatial learning in aged animals, without a significant effect in young rats. These results support the hypothesis that increasing intracellular neuronal buffering power for calcium in aged rats ameliorates age-related impaired synaptic plasticity and learning.

Evolution of ultrasound guided axillary brachial plexus blockade: retrospective analysis of 662 blocks.

Purpose: Ultrasound (US) is being used increasingly to guide needle placement during axillary brachial plexus blockade (AXB). This retrospective study investigated whether US guidance can increase the success rate, decrease block onset time, and reduce local anesthetic (LA) volume for AXB compared to a traditional (TRAD) approach, namely, peripheral nerve stimulation (PNS) and transarterial (TA) techniques.Methods: The anesthetic records, operative reports, discharge summaries, and surgical consultation notes of all patients who had undergone AXB for surgical anesthesia at the Toronto Western Hospital, between October 2003 and November 2006 were, retrospectively reviewed for evidence of block success and associated complications. Block success was defined as the achievement of surgical anesthesia without additional LA supplementation.Results: Among the 662 patients, 535 patients underwent AXB using US guidance (US group), and 127 using TRAD techniques (TRAD group), namely, 56 using PNS (PNS subgroup) and 71 using the TA technique (TA subgroup). The block success rate was higher in the US group compared to the TRAD group (91.6%vs 81.9%,p=0.003). The LA volume used for AXB was less in the US group compared to the TRAD group (39.8±6.4 mLvs 46.7±17.1 mL,p<0.0001). Ultrasound group patients spent less time in the block procedure room than those in the TRAD group (30.6±14.2 minvs 40.1±27.3 min,p<0.0001). When analyzed by subgroup, the US group demonstrated significantly greater success and shorter duration in the block room compared to the PNS subgroup, but not the TA subgroup. Complications (inadvertent intravenous LA injection, and transient neuropathy) were lower in the US group compared to the TRAD group (0.37%vs 3.15%,p=0.014).Conclusions: Our results suggest that US-guided AXB may improve block success, reduce the local anesthetic volume used, and shorten the time spent in the block room compared to traditional nerve localization techniques.RésuméObjectif: L’ultrason (US ou échoguidage) est de plus en plus utilisé pour guider le positionnement de l’aiguille pendant le bloc du plexus brachial par approche axillaire (AXB). Cette étude rétrospective a cherché à déterminer si l’échoguidage peut améliorer le taux de réussite, raccourcir le délai d’installation et réduire le volume d’anesthésique local (AL) pour l’AXB par rapport à une approche traditionnelle (TRAD), c’est-à-dire aux techniques de stimulation des nerfs périphériques (PNS) et par transfixion artérielle (TA).Méthode: Les dossiers anesthésiques, les dossiers d’opération, les résumés de congés et les notes de consultation chirurgicale de tous les patients subissant un AXB dans le cadre d’une anesthésie chirurgicale au Toronto Western Hospital entre octobre 2003 et novembre 2006 ont été évalués rétrospectivement afin de trouver des données probantes quant à la réussite du bloc et aux complications associées. La réussite d’un bloc était définie comme l’obtention d’une anesthésie chirurgicale sans addition supplémentaire d’AL.Résultats: Parmi les 662 patients dont les dossiers ont été évalués, 535 patients ont subi un AXB échoguidé (groupe US), et 127 à l’aide de techniques traditionnelles (groupe TRAD), dont 56 patients à l’aide de PNS (sous-groupe PNS) et 71 à l’aide de la technique TA (sous-groupe TA). Le taux de réussite du bloc était plus élevé dans le groupe US comparé au groupe TRAD (91,6 % vs 81,9 %, p=0,003). Le volume AL utilisé pour l’AXB était moins élevé dans le groupe US par rapport au groupe TRAD (39,8±6,4 mL vs 46,7±17,1 mL, p<0,0001). Les patients du groupe échoguidé ont passé moins de temps en salle d’anesthésie régionale que ceux du groupe TRAD (30,6±14,2 min vs 40,1±27,3 min, p<0,0001). Lorsque les résultats ont été analysés par sous-groupe, le groupe US a montré un taux de réussite significativement plus élevé et un séjour plus court en salle d’anesthésie régionale par rapport au groupe PNS, mais non par rapport au groupe TA. Les complications (injection intraveineuse involontaire d’AL et neuropathie temporaire) étaient moins courantes dans le groupe US que dans le groupe TRAD (0,37 % vs 3,15 %, p=0,014).Conclusions: Nos résultats suggèrent qu’un bloc du plexus brachial par approche axillaire échoguidée pourrait améliorer le taux de réussite du bloc, réduire le volume d’anesthésique local utilisé, et réduire le temps passé en salle d’anesthésie régionale par rapport aux techniques traditionnelles de localisation des nerfs.

Venous air embolism during awake craniotomy in a supine patient.

PurposeTo report a non-fatal case of intraoperative venous air embolism (VAE) during an awake craniotomy. VAE presented with unusual clinical features.Clinical featuresVAE during an awake craniotomy has not been reported frequently. The patient we describe presented with persistent coughing followed by tachypnea, hypoxia and reduction in end-tidal CO2 during dural opening while undergoing an awake craniotomy in the supine position. Cardiovascular variables were stable during the episode except for transient hypertension. Having ruled out airway obstruction and low cardiac output, we concluded that air embolism was the cause. The patient responded immediately to the standard treatment of air embolism and recovered without any complication.ConclusionThis case illustrates a VAE during an awake craniotomy and emphasizes the importance of early diagnosis in the management.RésuméObjectifPrésenter un cas non mortel d’aéroembolie veineuse peropératoire (AEV) survenue pendant une craniotomie vigile. L’AEV présentait des caractéristiques cliniques inhabituelles.Éléments cliniquesL’AEV qui survient pendant la craniotomie vigile n’a pas été souvent rapportée. Le patient que nous décrivons a présenté une toux persistante suivie de tachypnée, d’hypoxie et d’une baisse du CO2 télé-expiratoire pendant l’ouverture durale pour une craniotomie vigile en décubitus dorsal. Les variables hémodynamiques ont été stables pendant l’épisode, sauf pour l’hypertension transitoire. Nous avons d’abord écarté la possibilité d’une obstruction des voies aériennes et un faible débit cardiaque pour en arriver au diagnostic d’embolie gazeuse. Le patient a immédiatement réagi au traitement standard de l’embolie gazeuse et il s’est remis sans complication.ConclusionCe cas illustre un AEV pendant une craniotomie vigile et souligne l’importance d’un diagnostic précoce pour le traitement.

Disclosure of Risks Associated With Regional Anesthesia: A Survey of Academic Regional Anesthesiologists

Background and Objectives: In view of the relatively few large studies available to estimate the rates of complications following regional anesthesia, we aimed to identify and quantify the risks that academic regional anesthesiologists and regional anesthesia fellows disclose to their patients before performing central and peripheral nerve blockade. Methods: We asked 23 North American regional anesthesia fellowship program directors to distribute a questionnaire to the regional anesthesiologists and regional anesthesia fellows at their institutions. The questionnaire was designed to capture the risks and corresponding incidences that are routinely disclosed to patients before performing the most common central and peripheral nerve block techniques. Results: The total number of respondents was 79 from 12 different institutions. Fifty-eight (74%) respondents disclose risks of regional anesthesia in order to allow their patients to make an informed choice, whereas 20 (26%) disclose risks for medicolegal reasons. For central neural blockade, the most commonly disclosed risks are headache, local pain/discomfort, and infection. For peripheral nerve blockade, the most commonly disclosed risks are transient neuropathy, local pain/discomfort, and infection. For both central and peripheral nerve blockade, the risks most commonly disclosed are also those with the highest-reported incidences. Conclusions: The risks of regional anesthesia most commonly disclosed to patients by academic regional anesthesiologists and regional anesthesia fellows are benign in nature and occur frequently. Severe complications of regional anesthesia are far less commonly disclosed. The incidences of severe complications disclosed by academic regional anesthesiologists and their fellows can be inconsistent with those cited in the contemporary literature.

Practice patterns related to block selection, nerve localization and risk disclosure: a survey of the American Society of Regional Anesthesia and Pain Medicine.

Background and Objectives: We aimed to identify current clinical practice patterns among members of the American Society of Regional Anesthesia and Pain Medicine (ASRA) members that relate to complications of regional anesthesia (RA). Methods: Invitations were posted to the 3,732 ASRA members, to participate in our survey. Members were asked to report the types and numbers of blocks performed annually, preferred nerve localization techniques, and routine risk disclosure practices prior to common neuraxial (NAB) and peripheral nerve (PNB) block techniques. Results: The number of respondents was 801 (response rate: 21.7%). Approximately half of the respondents perform >100 spinal and epidural blocks but <50 of each listed PNB annually. With the exception of axillary block, nerve stimulation is the overwhelmingly preferred nerve localization technique for PNB. Five hundred twenty‐nine respondents (66.2%) disclose of RA primarily to allow patients to make an informed choice, while 227 (28.4%) disclose for medicolegal reasons. For NAB, the most commonly disclosed risks are headache and local pain/discomfort. Neurological complications following NAB such as permanent neuropathy and paralysis are inconsistently disclosed. For PNB, the most commonly disclosed risks are local pain/discomfort and transient neuropathy. The least commonly disclosed risks for both NAB and PNB include seizures, respiratory failure, cardiac arrest, and death. With the exception of headache following spinal anesthesia (1:100) and Horners syndrome following interscalene block (1:10), there is little consensus regarding the perceived incidence of complications. Conclusions: Based on a 22% response rate, our survey suggests that the risks of RA most commonly disclosed to patients by ASRA members are benign while severe complications of RA are far less commonly disclosed. There is little agreement among ASRA members regarding their perceived incidence of complications following RA.

Loss of the airway during tracheostomy: rescue oxygenation and re-establishment of the airway.

PurposeTo describe loss of the airway during tracheostomy and suggest a method for re-establishment of the airway and providing rescue oxygenation.Clinical featuresA 22-yr-old female diagnosed with encephalomyelopathy was admitted to the intensive care unit with a progressively deteriorating level of consciousness and respiratory failure requiring intubation and ventilation. Several weeks later, an elective tracheostomy was performed under anesthesia. The surgeon made an anterior tracheal wall incision and inserted a cuffed #6 Shiley tracheostomy tube. No end-tidal CO2 was detected and the patient could not be ventilated. After another failed attempt at insertion of a second tracheostomy tube, the diagnosis was made of a false passage within the trachea. The Shiley tracheostomy tube was removed and a #6 regular endotracheal tube was introduced in the trachea through the tracheostomy incision. The patient now could be ventilated with difficulty and low readings of end-tidal CO2 were noted. Despite all efforts to further ventilate the patient, the arterial oxygen saturation never recovered, resulting in cardiac arrest.ConclusionTo restore a lost airway during tracheostomy, we recommend that a jet ventilation airway exchange catheter (JVAE) be inserted in the endotracheal tube through a bronchoscope port attachment prior to surgical entry into the trachea. The JVAE will also ensure continued ability to oxygenate the patient.RésuméObjectifDécrire la perte du contrôle des voies aériennes pendant une trachéotomie et suggérer une méthode pour le rétablissement de la ventilation et l’apport d’oxygène de secours.Éléments cliniquesUne femme de 22 ans, atteinte d’encéphalomyélopathie, a été admise à l’unité des soins intensifs. Son état présentait une détérioration progressive du niveau de conscience et une insuffisance respiratoire nécessitant l’intubation et la ventilation. Quelques semaines plus tard, une trachéotomie non urgente a été réalisée sous anesthésie. Le chirurgien a pratiqué une incision à la paroi antérieure de la trachée et inséré une canule de trachéotomie à ballonnet no 6 de Shiley. Le CO2 de fin d’expiration n’a pas été détecté et la ventilation était impossible. L’essai d’une seconde canule de trachéotomie ayant échoué, on a conclu à une insertion paratrachéale de la canule. On a remplacé la canule de Shiley par une canule endotrachéale régulière no 6, introduite dans l’incision trachéale. On pouvait maintenant ventiler, mais avec peine et on a enregistré de faibles relevés de CO2 de fin d’expiration. Malgré tous les efforts supplémentaires fournis pour restaurer la ventilation, la saturation en oxygène du sang artériel n’est jamais revenue à la normale, le tout amenant à un arrêt cardiaque.ConclusionPour rétablir le contrôle des voies aériennes, nous recommandons l’utilisation d’une sonde d’échange permettant la ventilation en jet à haute fréquence (VJHF). Cette sonde devrait glisser par l’ouverture d’un connecteur (utilisé pour les bronchoscopies flexibles) dans une canule endotrachéale et serait mise ne place avant l’introduction chirurgicale dans la trachée. La sonde d’échange (VJHF) maintiendra la capacité d’oxygéner le patient en tout temps.