Showing papers in "BJA: British Journal of Anaesthesia in 2009"

Near-infrared spectroscopy as an index of brain and tissue oxygenation

Abstract: Continuous real-time monitoring of the adequacy of cerebral perfusion can provide important therapeutic information in a variety of clinical settings. The current clinical availability of several non-invasive near-infrared spectroscopy (NIRS)-based cerebral oximetry devices represents a potentially important development for the detection of cerebral ischaemia. In addition, a number of preliminary studies have reported on the application of cerebral oximetry sensors to other tissue beds including splanchnic, renal, and spinal cord. This review provides a synopsis of the mode of operation, current limitations and confounders, clinical applications, and potential future uses of such NIRS devices.

Major complications of central neuraxial block: report on the Third National Audit Project of the Royal College of Anaesthetists†

Abstract: Background Serious complications of central neuraxial block (CNB) are rare. Limited information on their incidence and impact impedes clinical decision-making and patient consent. The Royal College of Anaesthetists Third National Audit Project was designed to inform this situation. Methods A 2 week national census estimated the number of CNB procedures performed annually in the UK National Health Service. All major complications of CNBs performed over 1 yr (vertebral canal abscess or haematoma, meningitis, nerve injury, spinal cord ischaemia, fatal cardiovascular collapse, and wrong route errors) were reported. Each case was reviewed by an expert panel to assess causation, severity, and outcome. ‘Permanent' injury was defined as symptoms persisting for more than 6 months. Efforts were made to validate denominator (procedures performed) and numerator (complications) data through national databases. Results The census phase produced a denominator of 707 455 CNB. Eighty-four major complications were reported, of which 52 met the inclusion criteria at the time they were reported. Data were interpreted ‘pessimistically' and ‘optimistically'. ‘Pessimistically' there were 30 permanent injuries and ‘optimistically' 14. The incidence of permanent injury due to CNB (expressed per 100 000 cases) was ‘pessimistically' 4.2 (95% confidence interval 2.9–6.1) and ‘optimistically' 2.0 (1.1–3.3). ‘Pessimistically' there were 13 deaths or paraplegias, ‘optimistically' five. The incidence of paraplegia or death was ‘pessimistically' 1.8 per 100 000 (1.0–3.1) and ‘optimistically' 0.7 (0–1.6). Two-thirds of initially disabling injuries resolved fully. Conclusions The data are reassuring and suggest that CNB has a low incidence of major complications, many of which resolve within 6 months.

Postoperative delirium and cognitive dysfunction

Abstract: Postoperative delirium and cognitive dysfunction (POCD) are topics of special importance in the geriatric surgical population. They are separate entities, whose relationship has yet to be fully elucidated. Although not limited to geriatric patients, the incidence and impact of both are more profound in geriatric patients. Delirium has been shown to be associated with longer and more costly hospital course and higher likelihood of death within 6 months or postoperative institutionalization. POCD has been associated with increased mortality, risk of leaving the labour market prematurely, and dependency on social transfer payments. Here, we review their definitions and aetiology, and discuss treatment and prevention in elderly patients undergoing major non-cardiac surgery. Good basic care demands identification of at-risk patients, awareness of common perioperative aggravating factors, simple prevention interventions, recognition of the disease states, and basic treatments for patients with severe hyperactive manifestations.

Ultrasound guidance compared with electrical neurostimulation for peripheral nerve block: a systematic review and meta-analysis of randomized controlled trials

Abstract: Background. Despite the growing interest in the use of ultrasound (US) imaging to guide performance of regional anaesthetic procedures such as peripheral nerve blocks, controversy still exists as to whether US is superior to previously developed nerve localization techniques such as the use of a peripheral nerve stimulator (PNS). We sought to clarify this issue by performing a systematic review and meta-analysis of all randomized controlled trials that have compared these two methods of nerve localization. Methods. We searched Ovid MEDLINE w , the Cochrane Central Register of Controlled Trials w , and Google Scholar databases and also the reference lists of relevant publications for eligible studies. A total of 13 studies met our criteria and were included for analysis. Studies were rated for methodological quality by two reviewers. Data from these studies were

Bone cement implantation syndrome

Abstract: Bone cement implantation syndrome (BCIS) is poorly understood. It is an important cause of intraoperative mortality and morbidity in patients undergoing cemented hip arthroplasty and may also be seen in the postoperative period in a milder form causing hypoxia and confusion. Hip arthroplasty is becoming more common in an ageing population. The older patient may have co-existing pathologies which can increase the likelihood of developing BCIS. This article reviews the definition, incidence, clinical features, risk factors, aetiology, pathophysiology, risk reduction, and management of BCIS. It is possible to identify high risk groups of patients in which avoidable morbidity and mortality may be minimized by surgical selection for uncemented arthroplasty. Invasive anaesthetic monitoring should be considered during cemented arthroplasty in high risk patients.

Ultrasound-guided transversus abdominis plane block: description of a new technique and comparison with conventional systemic analgesia during laparoscopic cholecystectomy

Abstract: Background The transversus abdominis plane (TAP) block is usually performed by landmark-based methods. This prospective, randomized, and double-blinded study was designed to describe a method of ultrasound-guided TAP block and to evaluate the intra- and postoperative analgesic efficacy in patients undergoing laparoscopic cholecystectomy under general anaesthesia with or without TAP block. Methods Forty-two patients undergoing laparoscopic cholecystectomy were randomized to receive standard general anaesthetic either with (Group A, n=21) or without TAP block (Group B, n=21). Ultrasound-guided bilateral TAP block was performed with a high frequent linear ultrasound probe and an in-plane needle guidance technique with 15 ml bupivacaine 5 mg ml−1 on each side. Intraoperative use of sufentanil and postoperative demand of morphine using a patient-controlled analgesia device were recorded. Results Ultrasonographic visualization of the relevant anatomy, detection of the shaft and tip of the needle, and the spread of local anaesthetic were possible in all cases where a TAP block was performed. Patients in Group A received significantly more intraoperative sufentanil and postoperative morphine compared with those in Group B [mean (sd) 8.6 (3.5) vs 23.0 (4.8) μg, P Conclusions Ultrasonographic guidance enables exact placement of the local anaesthetic for TAP blocks. In patients undergoing laparoscopic cholecystectomy under standard general anaesthetic, ultrasound-guided TAP block substantially reduced the perioperative opioid consumption.

Nasal high-flow therapy delivers low level positive airway pressure

Abstract: Background The aim of this prospective study was to determine whether a level of positive airway pressure was generated in participants receiving nasal high flow (NHF) delivered by the Optiflow™ system (Fisher and Paykel Healthcare Ltd, Auckland, New Zealand) in a cardiothoracic and vascular intensive care unit (ICU). Methods Nasopharyngeal airway pressure was measured in 15 postoperative cardiac surgery adult patients who received both NHF and standard facemask therapy at a flow rate of 35 litre min−1. Measurements were repeated in the open mouth and closed mouth positions. Mean airway pressure was determined by averaging the pressures at the peak of inspiration of each breath within a 1 min period, allowing the entire pressure profile of each breath to be included within the calculation. Results Low level positive pressure was demonstrated with NHF at 35 litre min−1 with mouth closed when compared with a facemask. NHF generated a mean nasopharyngeal airway pressure of mean (sd) 2.7 (1.04) cm H2O with the mouth closed. Airway pressure was significantly higher when breathing with mouth closed compared with mouth open (P≤0.0001). Conclusions This study demonstrated that a low level of positive pressure was generated with NHF at 35 litre min−1 of gas flow. This is consistent with results obtained in healthy volunteers. Australian Clinical Trials Registry www.actr.org.au ACTRN012606000139572.

Goal-directed haemodynamic therapy and gastrointestinal complications in major surgery: a meta-analysis of randomized controlled trials

Abstract: Postoperative gastrointestinal (GI) dysfunction is one of the most frequent complications in surgical patients. Most cases are associated with episodes of splanchnic hypoperfusion due to hypovolaemia or cardiac dysfunction. It has been suggested that perioperative haemodynamic goal-directed therapy (GDT) may reduce the incidence of these complications in cardiac surgery, and other surgery, but clear evidence is lacking. We have undertaken a meta-analysis of the effects of GDT on postoperative GI and liver complications. A systematic search, using MEDLINE, EMBASE, and The Cochrane Library databases, was performed. Sixteen randomized controlled trials (3410 participants) met the inclusion criteria. Data synthesis was obtained using odds ratio (OR) with 95% confidence interval (CI) by random-effects model. Statistical heterogeneity was assessed by Q and I2 statistics. GI complications were ranked as major (required radiological or surgical intervention or life-threatening condition) or minor (no or only pharmacological treatment required). Major GI complications were significantly reduced by GDT when compared with a control group (OR, 0.42; 95% CI, 0.27–0.65). Minor GI complications were also significantly decreased in the GDT group (OR, 0.29; 95% CI, 0.17–0.50). Treatment did not reduce hepatic injury rate (OR, 0.54; 95% CI, 0.19–1.55). Quality sensitive analyses confirmed the main overall results. In patients undergoing major surgery, GDT, by maintaining an adequate systemic oxygenation, can protect organs particularly at risk of perioperative hypoperfusion and is effective in reducing GI complications.

Prospective randomized controlled multi-centre trial of cuffed or uncuffed endotracheal tubes in small children

Abstract: BACKGROUND: The use of cuffed tracheal tubes (TTs) in small children is still controversial. The aim of this study was to compare post-extubation morbidity and TT exchange rates when using cuffed vs uncuffed tubes in small children. METHODS: Patients aged from birth to 5 yr requiring general anaesthesia with TT intubation were included in 24 European paediatric anaesthesia centres. Patients were prospectively randomized into a cuffed TT group (Microcuff PET) and an uncuffed TT group (Mallinckrodt, Portex, Rusch, Sheridan). Endpoints were incidence of post-extubation stridor and the number of TT exchanges to find an appropriate-sized tube. For cuffed TTs, minimal cuff pressure required to seal the airway was noted; maximal cuff pressure was limited at 20 cm H(2)O with a pressure release valve. Data are mean (SD). RESULTS: A total of 2246 children were studied (1119/1127 cuffed/uncuffed). The age was 1.93 (1.48) yr in the cuffed and 1.87 (1.45) yr in the uncuffed groups. Post-extubation stridor was noted in 4.4% of patients with cuffed and in 4.7% with uncuffed TTs (P=0.543). TT exchange rate was 2.1% in the cuffed and 30.8% in the uncuffed groups (P<0.0001). Minimal cuff pressure required to seal the trachea was 10.6 (4.3) cm H(2)O. CONCLUSIONS: The use of cuffed TTs in small children provides a reliably sealed airway at cuff pressures of

Determination of spread of injectate after ultrasound-guided transversus abdominis plane block: a cadaveric study

Abstract: Background The transversus abdominis plane (TAP) block is a new regional anaesthesia technique that provides analgesia after abdominal surgery. It involves injection of local anaesthetic into the plane between the transversus abdominis and the internal oblique muscles. The TAP block can be performed using a landmark technique through the lumbar triangle or with ultrasound guidance. The goal of this anatomical study with dye injection into the TAP and subsequent cadaver dissections was to establish the likely spread of local anaesthesia in vivo and the segmental nerve involvement resulting from ultrasound-guided TAP block. Methods An ultrasound-guided injection of aniline dye into the TAP was performed for each hemi-abdominal wall of 10 unembalmed human cadavers and this was followed by dissection to determine the extent of dye spread and nerve involvement in the dye injection. Results After excluding one pilot specimen and one with advanced tissue decomposition, 16 hemi-abdominal walls were successfully injected and dissected. The lower thoracic nerves (T10–T12) and first lumbar nerve (L1) were found emerging from posterior to anterior between the costal margin and the iliac crest. Segmental nerves T10, T11, T12, and L1 were involved in the dye in 50%, 100%, 100%, and 93% of cases, respectively. Conclusions This anatomical study shows that an ultrasound-guided TAP injection cephalad to the iliac crest is likely to involve the T10–L1 nerve roots, and implies that the technique may be limited to use in lower abdominal surgery.

Analgesic efficacy of ultrasound-guided transversus abdominis plane block in patients undergoing open appendicectomy

Abstract: Background Transversus abdominis plane (TAP) block is a new regional anaesthetic technique that blocks abdominal neural afferents by introducing local anaesthetic into the neuro-fascial plane between the internal oblique and the transversus abdominis muscles. We evaluated its analgesic efficacy in patients undergoing open appendicectomy in a randomized controlled double-blinded clinical trial. Methods Fifty-two adult patients undergoing open appendicectomy were randomized to undergo standard care (n=26) or to undergo a right-sided TAP block with bupivacaine (n=26). In addition, all patients received patient-controlled i.v. morphine analgesia, regular acetaminophen, and non-steroidal anti-inflammatory drug, as required, in the postoperative period. All patients received standard anaesthetic, and after induction of anaesthesia, the TAP group received an ultrasound-guided unilateral TAP block. Each patient was assessed after operation by a blinded investigator at 30 min and 24 h after surgery. Results Ultrasound-guided TAP block significantly reduced postoperative morphine consumption in the first 24 h [mean (sd) 28 (18) vs 50 (19) mg, P Conclusions Ultrasound-guided TAP block holds considerable promise as a part of a balanced postoperative analgesic regimen for patients undergoing open appendicectomy.

Ultrasound-guided transversus abdominis plane block for analgesia after Caesarean delivery

Abstract: Background The landmark-guided transversus abdominis plane (TAP) block is an effective method of providing postoperative analgesia in patients undergoing lower abdominal surgery. We evaluated the analgesic efficacy of the ultrasound (US)-guided TAP block in patients undergoing Caesarean delivery. Methods A randomized, double-blind, placebo-controlled trial was performed at a tertiary maternity hospital. Fifty women undergoing Caesarean delivery received bilateral US-guided TAP blocks with either ropivacaine 0.5% or saline. All participants received a spinal anaesthetic with bupivacaine and fentanyl, followed by postoperative acetaminophen, non-steroidal anti-inflammatory drugs, and patient-controlled i.v. morphine without long-acting intrathecal opioids. Each patient was assessed 24 h after delivery for morphine usage, average pain score, nausea, vomiting, pruritus, drowsiness, and satisfaction with pain relief. Results Forty-seven participants completed the trial, 23 in the active group and 24 in the placebo group. Total morphine use in 24 h was reduced in the active group (median 18.0 mg) compared with the placebo group (median 31.5 mg, P Conclusions The US-guided TAP block reduces morphine requirements after Caesarean delivery when used as a component of a multimodal analgesic regimen. Registered with the Australia New Zealand Clinical Trials Registry ACTRN12608000540314. URL: http://www.anzctr.org.au/trial_view.aspx?ID=83176.

Pharmacokinetic models for propofol—defining and illuminating the devil in the detail

Abstract: The recently introduced open-target-controlled infusion (TCI) systems can be programmed with any pharmacokinetic model, and allow either plasma- or effect-site targeting. With effect-site targeting the goal is to achieve a user-defined target effect-site concentration as rapidly as possible, by manipulating the plasma concentration around the target. Currently systems are pre-programmed with the Marsh and Schnider pharmacokinetic models for propofol. The former is an adapted version of the Gepts model, in which the rate constants are fixed, whereas compartment volumes and clearances are weight proportional. The Schnider model was developed during combined pharmacokinetic-pharmacodynamic modelling studies. It has fixed values for V1, V3, k(13), and k(31), adjusts V2, k(12), and k(21) for age, and adjusts k(10) according to total weight, lean body mass (LBM), and height. In plasma targeting mode, the small, fixed V1 results in very small initial doses on starting the system or on increasing the target concentration in comparison with the Marsh model. The Schnider model should thus always be used in effect-site targeting mode, in which larger initial doses are administered, albeit still smaller than for the Marsh model. Users of the Schnider model should be aware that in the morbidly obese the LBM equation can generate paradoxical values resulting in excessive increases in maintenance infusion rates. Finally, the two currently available open TCI systems implement different methods of effect-site targeting for the Schnider model, and in a small subset of patients the induction doses generated by the two methods can differ significantly.

Addition of clonidine or dexmedetomidine to bupivacaine prolongs caudal analgesia in children

Abstract: Background Caudal block is a common technique for paediatric analgesia but with the disadvantage of short duration of action after single injection. Caudal dexmedetomidine and clonidine could offer significant analgesic benefits. We compared the analgesic effects and side-effects of dexmedetomidine and clonidine added to bupivacaine in paediatric patients undergoing lower abdominal surgeries. Methods Sixty patients (6 months to 6 yr) were evenly and randomly assigned into three groups in a double-blinded manner. After sevoflurane in oxygen anaesthesia, each patient received a single caudal dose of bupivacaine 0.25% (1 ml kg−1) combined with either dexmedetomidine 2 µg kg−1 in normal saline 1 ml, clonidine 2 µg kg−1 in normal saline 1 ml, or corresponding volume of normal saline according to group assignment. Haemodynamic variables, end-tidal sevoflurane, and emergence time were monitored. Postoperative analgesia, use of analgesics, and side-effects were assessed during the first 24 h. Results Addition of dexmedetomidine or clonidine to caudal bupivacaine significantly promoted analgesia time [median (95% confidence interval, CI): 16 (14–18) and 12 (3–21) h, respectively] than the use of bupivacaine alone [median (95% CI): 5 (4–6) h] with P Conclusions Addition of dexmedetomidine or clonidine to caudal bupivacaine significantly promoted analgesia in children undergoing lower abdominal surgeries with no significant advantage of dexmedetomidine over clonidine and without an increase in incidence of side-effects.

Bleeding management with fibrinogen concentrate targeting a high-normal plasma fibrinogen level: a pilot study

Abstract: Complex cardiac surgery is frequently accompanied by excessive perioperative bleeding because of coagulation system impairment, inadequate surgical haemostasis, or both.1 Bleeding increases the risk of re-exploration, allogeneic blood transfusion, or perioperative myocardial infarction, and consequently, associated morbidity and mortality.2 Aortic valve operation and ascending aorta replacement (AV–AA) typically involves hypothermia, prolonged cardiopulmonary bypass (CPB), and large graft anastomoses, and is associated with an increased risk of intra- and postoperative blood loss and high transfusion rates.3,4 Conventional haemostatic therapy consists of transfusion of allogeneic blood products that include fresh-frozen plasma (FFP), platelet concentrate, and cryoprecipitate. However, although the use of these products was developed empirically, their haemostatic efficacy has not been evaluated thoroughly in the surgical setting.5,6 Haemocomplettan® P (brand name in Europe)/Riastap (brand name in USA) (CSL Behring, Marburg, Germany) is a highly purified, lyophilized, virus-inactivated fibrinogen concentrate obtained from human plasma that can be rapidly reconstituted without the need for thawing and cross-matching, which are necessary for FFP and cryoprecipitate. The administration of fibrinogen concentrate was originally reserved for replacement therapy in congenital fibrinogen deficiency, and in the USA, Riastap is only approved for this indication. In the meantime, European reports on haemostatic therapy with Haemocomplettan® P in acquired perioperative deficiency of fibrinogen have been published.7–11 Acquired fibrinogen deficiency occurring during and after CPB is associated with increased bleeding after cardiac surgery.12,13 However, the haemostatic efficacy of fibrinogen concentrate in correcting such deficiency in complex cardiac surgery has not been investigated to date. To reduce blood component transfusion in cardiac surgery, point-of-care methods such as thrombelastography/thromboelastometry have been applied in algorithms supporting bleeding management in relation to blood clotting quality.14–16 Thromboelastometry (ROTEM®; Pentapharm GmbH, Munich, Germany) assesses the viscoelasticity of whole blood. One of the ROTEM® tests, the FIBTEM test, provides prompt information on the clot strength specifically attributed to fibrin/fibrinogen using cytochalasin-D-induced inactivation of platelets in vitro.17 This test may be used to guide the administration of fibrinogen concentrate for prompt haemostatic therapy.9–11 We hypothesized that postoperative haemostasis could be improved by increasing plasma fibrinogen concentrations, since bleeding complications were observed to be lower in patients with high perioperative fibrinogen concentrations.12,13 The primary aim of this pilot study was to evaluate whether FIBTEM-guided intraoperative fibrinogen repletion was able to reduce the use of allogeneic blood products and postoperative bleeding in patients undergoing AV–AA.

Real-time ultrasound-guided paramedian epidural access: evaluation of a novel in-plane technique

Abstract: Background Current methods of locating the epidural space rely on surface anatomical landmarks and loss-of-resistance (LOR). We are not aware of any data describing real-time ultrasound (US)-guided epidural access in adults. Methods We evaluated the feasibility of performing real-time US-guided paramedian epidural access with the epidural needle inserted in the plane of the US beam in 15 adults who were undergoing groin or lower limb surgery under an epidural or combined spinal–epidural anaesthesia. Results The epidural space was successfully identified in 14 of 15 (93.3%) patients in 1 (1–3) attempt using the technique described. There was a failure to locate the epidural space in one elderly man. In 8 of 15 (53.3%) patients, studied neuraxial changes, that is, anterior displacement of the posterior dura and widening of the posterior epidural space, were seen immediately after entry of the Tuohy needle and expulsion of the pressurized saline from the LOR syringe into the epidural space at the level of needle insertion. Compression of the thecal sac was also seen in two of these patients. There were no inadvertent dural punctures or complications directly related to the technique described. Anaesthesia adequate for surgery developed in all patients after the initial spinal or epidural injection and recovery from the epidural or spinal anaesthesia was also uneventful. Conclusions We have demonstrated the successful use of real-time US guidance in combination with LOR to saline for paramedian epidural access with the epidural needle inserted in the plane of the US beam.

Finding the optimal concentration range for fibrinogen replacement after severe haemodilution: an in vitro model

Abstract: Background Replacement of fibrinogen is presumably the key step in managing dilutional coagulopathy. We performed an in vitro study hypothesizing that there is a minimal fibrinogen concentration in diluted whole blood above which the rate of clot formation approaches normal. Methods Blood samples from six healthy volunteers were diluted 1:5 v/v with saline keeping haematocrit at 24% using red cell concentrates. We measured coagulation factors and thrombin generation in plasma at baseline and after dilution. Thromboelastometry was used to evaluate (i) speed and quality of clot formation in diluted samples supplemented with fibrinogen 50–300 mg dl −1 and (ii) clot resistance to fibrinolysis. Diluted and undiluted samples with no added fibrinogen served as controls. Results Coagulation parameters and platelets were reduced by 74–85% after dilution. Peak thrombin generation was reduced by 56%. Adding fibrinogen led to a concentration-dependent improvement of all thromboelastometric parameters. The half maximal effective concentration (EC50) for fibrinogen replacement in haemodiluted blood was calculated to be 125 mg dl −1 . Adding tissue plasminogen activator, 0.15 μg ml −1 , led to a decrease of clot firmness and lysis time. Conclusions The target plasma concentration for fibrinogen replacement was predicted by these in vitro results to be greater than 200 mg dl −1 as only these concentrations optimized the rate of clot formation. This concentration is twice the level suggested by the current transfusion guidelines. Although improved, clots were prone to fibrinolysis indicating that the efficacy of fibrinogen therapy may be influenced by co-existing fibrinolytic tendency occurring during dilutional coagulopathy.

Failed spinal anaesthesia: mechanisms, management, and prevention

Abstract: Although spinal (subarachnoid or intrathecal) anaesthesia is generally regarded as one of the most reliable types of regional block methods, the possibility of failure has long been recognized. Dealing with a spinal anaesthetic which is in some way inadequate can be very difficult; so, the technique must be performed in a way which minimizes the risk of regional block. Thus, practitioners must be aware of all the possible mechanisms of failure so that, where possible, these mechanisms can be avoided. This review has considered the mechanisms in a sequential way: problems with lumbar puncture; errors in the preparation and injection of solutions; inadequate spreading of drugs through cerebrospinal fluid; failure of drug action on nervous tissue; and difficulties more related to patient management than the actual block. Techniques for minimizing the possibility of failure are discussed, all of them requiring, in essence, close attention to detail. Options for managing an inadequate block include repeating the injection, manipulation of the patient's posture to encourage wider spread of the injected solution, supplementation with local anaesthetic infiltration by the surgeon, use of systemic sedation or analgesic drugs, and recourse to general anaesthesia. Follow-up procedures must include full documentation of what happened, the provision of an explanation to the patient and, if indicated by events, detailed investigation.

Smoking and alcohol intervention before surgery: evidence for best practice.

Abstract: Smoking and hazardous drinking are common and important risk factors for an increased rate of complications after surgery. The underlying pathophysiological mechanisms include organic dysfunctions that can recover with abstinence. Abstinence starting 3-8 weeks before surgery will significantly reduce the incidence of several serious postoperative complications, such as wound and cardiopulmonary complications and infections. However, this intervention must be intensive to obtain sufficient effect on surgical complications. All patients presenting for surgery should be questioned regarding smoking and hazardous drinking, and interventions appropriate for the surgical setting applied.

Benefit and risk of intrathecal morphine without local anaesthetic in patients undergoing major surgery: meta-analysis of randomized trials

Abstract: Intrathecal morphine without local anaesthetic is often added to a general anaesthetic to prevent pain after major surgery. Quantification of benefit and harm and assessment of dose-response are needed. We performed a meta-analysis of randomized trials testing intrathecal morphine alone (without local anaesthetic) in adults undergoing major surgery under general anaesthesia. Twenty-seven studies (15 cardiac-thoracic, nine abdominal, and three spine surgery) were included; 645 patients received intrathecal morphine (dose-range, 100-4000 microg). Pain intensity at rest was decreased by 2 cm on the 10 cm visual analogue scale up to 4 h after operation and by about 1 cm at 12 and 24 h. Pain intensity on movement was decreased by 2 cm at 12 and 24 h. Opioid requirement was decreased intraoperatively, and up to 48 h after operation. Morphine-sparing at 24 h was significantly greater after abdominal surgery {weighted mean difference, -24.2 mg [95% confidence interval (CI) -29.5 to -19.0]}, compared with cardiac-thoracic surgery [-9.7 mg (95% CI -17.6 to -1.80)]. The incidence of respiratory depression was increased with intrathecal morphine [odds ratio (OR) 7.86 (95% CI 1.54-40.3)], as was the incidence of pruritus [OR 3.85 (95% CI 2.40-6.15)]. There was no evidence of linear dose-responsiveness for any of the beneficial or harmful outcomes. In conclusion, intrathecal morphine decreases pain intensity at rest and on movement up to 24 h after major surgery. Morphine-sparing is more pronounced after abdominal than after cardiac-thoracic surgery. Respiratory depression remains a major safety concern.

Apoptosis induction by different local anaesthetics in a neuroblastoma cell line

Abstract: Background Local anaesthetics are known to induce apoptosis in clinically relevant concentrations. Hitherto, it is unknown what determines the apoptotic potency of local anaesthetics. Therefore, we compared apoptosis induction by local anaesthetics related to their physicochemical properties in human neuronal cells. Methods Neuroblastoma cells (SHEP) were incubated with eight local anaesthetics, two of the ester and six of the amide types. At least, five concentrations of each local anaesthetic were evaluated. After incubation for 24 h, rates of cells in early apoptotic stages and overall cell death were evaluated by annexin V and 7-amino-actinomycin D double staining by flow cytometry. The concentrations that led to half-maximal neurotoxic effects (LD50) were calculated and compared for all local anaesthetics. Results All local anaesthetics were neurotoxic in a concentration-dependent manner. All drugs induced similar rates of early apoptotic cell formation at low concentrations, whereas at high concentrations, late apoptotic or necrotic cell death predominated. Comparison of LD50 values of the different local anaesthetics resulted in the following order of apoptotic potency from high to low toxicity: tetracaine>bupivacaine>prilocaine=mepivacaine=ropivacaine>lidocaine>procaine=articaine. The toxicity correlated with octanol/buffer coefficients and also with experimental potency of the local anaesthetic, but was unrelated to the structure (ester or amide type). Conclusions All commonly used local anaesthetics induce neuronal apoptosis in clinically used concentrations. The neurotoxicity correlates with lipid solubility and thus with the conduction blocking potency of the local anaesthetic, but is independent of the chemical class (ester/amide).

Effect of combining dexmedetomidine and morphine for intravenous patient-controlled analgesia

Abstract: Background Perioperative use of dexmedetomidine is associated with reduction in postoperative analgesic requirements. This study examined whether dexmedetomidine added to i.v. patient-controlled analgesia (PCA) morphine could improve analgesia while reducing opioid-related side-effects. Methods In this double-blinded, randomized, controlled study, 100 women undergoing abdominal total hysterectomy were allocated to receive either morphine 1 mg ml −1 alone (Group M) or morphine 1 mg ml −1 plus dexmedetomidine 5 μg ml −1 (Group D) for postoperative i.v. PCA, which was programmed to deliver 1 ml per demand with a 5 min lockout interval and no background infusion. Cumulative PCA requirements, pain intensities, cardiovascular and respiratory variables, and PCA-related adverse events were recorded for 24 h after operation. Results Compared with Group M, patients in Group D required 29% less morphine during the 0–24 h postoperative period and reported significantly lower pain levels from the second postoperative hour onwards and throughout the study. Whereas levels of sedation were similar between the groups at each observational time point, decreases in heart rate and mean blood pressure from presurgery baseline at 1, 2, and 4 h after operation were significantly greater in Group D (by a range of 5–7 beats min −1 and 10–13%, respectively). The 4–24 h incidence of nausea was significantly lower in Group D (34% vs 56.3%, P Conclusions The addition of dexmedetomidine to i.v. PCA morphine resulted in superior analgesia, significant morphine sparing, less morphine-induced nausea, and was devoid of additional sedation and untoward haemodynamic changes.

Does regional anaesthesia improve outcome after total hip arthroplasty? A systematic review

Abstract: Total hip arthroplasty (THA) is amenable to a variety of regional anaesthesia (RA) techniques that may improve patient outcome. We sought to answer whether RA decreased mortality, cardiovascular morbidity, deep venous thrombosis (DVT) and pulmonary embolism (PE), blood loss, duration of surgery, pain, opioid-related adverse effects, cognitive defects, and length of stay. We also questioned whether RA improved rehabilitation. To do so, we performed a systematic review of the contemporary literature to compare general anaesthesia (GA) and RA and also systemic and regional analgesia for THA. To reflect contemporary surgical and anaesthetic practice, only randomized controlled trials (RCTs) from 1990 onward were included. We identified 18 studies involving 1239 patients. Only two of the 18 trials were of Level I quality. There is insufficient evidence from RCTs alone to conclude if anaesthetic technique influenced mortality, cardiovascular morbidity, or the incidence of DVT and PE when using thromboprophylaxis. Blood loss may be reduced in patients receiving RA rather than GA for THA. Our review suggests that there is no difference in duration of surgery in patients who receive GA or RA. Compared with systemic analgesia, regional analgesia can reduce postoperative pain, morphine consumption, and nausea and vomiting. Length of stay is not reduced and rehabilitation does not appear to be facilitated by RA or analgesia for THA.

Reversal of neuromuscular block

Abstract: The use of anticholinesterases to reverse residual neuromuscular block is efficacious only if recovery is already established. It was originally advised that at least the second twitch (T2) of the train-of-four response should be detectable before neostigmine is administered. Even in these circumstances, the full effect of anticholinesterases takes up to 10 min to achieve. Anticholinesterases also have muscarinic side-effects that require an antimuscarinic to be administered concomitantly. An ideal reversal agent could be given at any time after the administration of a neuromuscular blocking agent (NMBA), and should have no muscarinic side-effects. The gamma cyclodextrin, sugammadex, has been demonstrated to effectively antagonize even profound block produced by the aminosteroid NMBAs, rocuronium and vecuronium, by chelating them. The complex is then excreted in the urine. Sugammadex is ineffective in antagonizing the benzylisoquinolinium NMBAs. The dose should be adjusted according to the degree of residual block: sugammadex 16 mg kg−1 for immediate reversal; 4–8 mg kg−1 for antagonizing profound block (post-tetanic count 1–2); and 2 mg kg−1 to antagonize moderate block (when T2 is detectable). As yet, the extent of any side-effects that may occur with this new antagonist is not fully known, although rarely adverse cardiovascular effects (hypotension, hypertension, prolonged QT interval) have already been reported.

Expected difficult tracheal intubation: a prospective comparison of direct laryngoscopy and video laryngoscopy in 200 patients

Abstract: Background The Berci–Kaplan video laryngoscope was developed to improve the visualization of the glottis and ease tracheal intubation. Whether this technique is also effective in patients with an expected difficult intubation is unclear. We have prospectively evaluated the conditions and success rate of tracheal intubation in patients with a Mallampati score of III or IV. Methods Two hundred patients, undergoing general anaesthesia, were randomized to be intubated using direct laryngoscopy ( n =100) or video laryngoscopy ( n =100). Visualization of the vocal cords, success rate, time for intubation, and the need for additional manoeuvres (laryngeal manipulations, head positioning, and Eschmann stylet) were evaluated. Results Video laryngoscopy produced better results for the visualization of the glottis using Cormack and Lehane criteria ( P n =92 vs 99, P =0.017), and the time for intubation [60 (77) vs 40 (31) s, P =0.0173]. In addition, the number of optimizing manoeuvres was also significantly decreased [1.2 (1.3) vs 0.5 (0.7), P Conclusions Video laryngoscopy, when compared with direct laryngoscopy for difficult intubations, provides a significantly better view of the cords, a higher success rate, faster intubations, and less need for optimizing manoeuvres. Therefore, we feel that the video laryngoscopy leads to a clinically relevant improvement of intubation conditions and can be recommended for difficult airway management.

Assessment of procedural skills in anaesthesia

Abstract: A key aspect of the practice of anaesthesia is the ability to perform practical procedures efficiently and safely. Decreased working hours during training, an increasing focus on patient safety, and greater accountability have resulted in a paradigm shift in medical education. The resulting international trend towards competency-based training demands robust methods of evaluation of all domains of learning. The assessment of procedural skills in anaesthesia is poor compared with other domains of learning and has fallen behind surgical fields. Logbooks and procedure lists are best suited to providing information regarding likely opportunities within training programmes. Retrospective global scoring and direct observation without specific criteria are unreliable. The current best evidence for a gold standard for assessment of procedural skills in anaesthesia consists of a combination of previously validated checklists and global rating scales, used prospectively by a trained observer, for a procedure performed in an actual patient. Future research should include core assessment parameters to ensure methodological rigor and facilitate robust comparisons with other studies: (i) reliability, (ii) validity, (iii) feasibility, (iv) cost-effectiveness, and (v) comprehensiveness with varying levels of difficulty. Simulation may become a key part of the future of formative and summative skills assessment in anaesthesia; however, research is required to develop and test simulators that are realistic enough to be suitable for use in high-stakes evaluation.

Acute compartment syndrome of the lower limb and the effect of postoperative analgesia on diagnosis

Abstract: Acute compartment syndrome can cause significant disability if not treated early, but the diagnosis is challenging. This systematic review examines whether modern acute pain management techniques contribute to delayed diagnosis. A total of 28 case reports and case series were identified which referred to the influence of analgesic technique on the diagnosis of compartment syndrome, of which 23 discussed epidural analgesia. In 32 of 35 patients, classic signs and symptoms of compartment syndrome were present in the presence of epidural analgesia, including 18 patients with documented breakthrough pain. There were no randomized controlled trials or outcome-based comparative trials available to include in the review. Pain is often described as the cardinal symptom of compartment syndrome, but many authors consider it unreliable. Physical examination is also unreliable for diagnosis. There is no convincing evidence that patient-controlled analgesia opioids or regional analgesia delay the diagnosis of compartment syndrome provided patients are adequately monitored. Regardless of the type of analgesia used, a high index of clinical suspicion, ongoing assessment of patients, and compartment pressure measurement are essential for early diagnosis.

Randomized controlled trial of the Pentax AWS®, Glidescope®, and Macintosh laryngoscopes in predicted difficult intubation

Abstract: Background The purpose of this study was to determine the potential for the Pentax AWS® and the Glidescope® to reduce the difficulty of tracheal intubation in patients at increased risk for difficult tracheal intubation, in a randomized, controlled clinical trial. Methods Seventy-five consenting patients presenting for surgery requiring tracheal intubation, and who were deemed to possess characteristics indicating an increased risk for difficult tracheal intubation, were randomly assigned to undergo intubation using a Macintosh, AWS®, or Glidescope® laryngoscope (n=25 patients per group). All patients were intubated by one of three anaesthetists experienced in the use of each laryngoscope. Results Both the Glidescope® and the AWS® significantly reduced the intubation difficulty score compared with the Macintosh. The rate of successful tracheal intubation was lower with the Macintosh (84%) compared with the Glidescope® (96%) or the AWS® (100%). There were no differences in the duration of tracheal intubation attempts between the devices. Both the Glidescope® and the AWS® significantly reduced the need for additional manoeuvres and improved the Cormack and Lehane view obtained at laryngoscopy, compared with the Macintosh. Tracheal intubation with the AWS® but not the Glidescope® reduced the degree of haemodynamic stimulation compared with the Macintosh laryngoscope. Conclusions The AWS® and the Glidescope® laryngoscopes reduced the difficulty of tracheal intubation to a similar extent compared with the Macintosh laryngoscope, in patients at increased risk for difficult tracheal intubation.

Perioperative visual loss: what do we know, what can we do?

Abstract: Perioperative visual loss (POVL), a rare, but devastating complication, can follow non-ocular surgery. Highest rates of visual loss are with cardiac and spine surgery. The main causes of visual loss after non-ocular surgery are retinal vascular occlusion and ischaemic optic neuropathy. This review updates readers on the incidence, suspected risk factors, diagnosis, and treatment of POVL due to these conditions.

Simultaneous targeting of multiple opioid receptors: a strategy to improve side-effect profile

Abstract: Opioid receptors are currently classified as µ (mu: mOP), δ (delta: dOP), κ (kappa: kOP) with a fourth related non-classical opioid receptor for nociceptin/orphainin FQ, NOP. Morphine is the current gold standard analgesic acting at MOP receptors but produces a range of variably troublesome side-effects, in particular tolerance. There is now good laboratory evidence to suggest that blocking DOP while activating MOP produces analgesia (or antinociception) without the development of tolerance. Simultaneous targeting of MOP and DOP can be accomplished by: (i) co-administering two selective drugs, (ii) administering one non-selective drug, or (iii) designing a single drug that specifically targets both receptors; a bivalent ligand. Bivalent ligands generally contain two active centres or pharmacophores that are variably separated by a chemical spacer and there are several interesting examples in the literature. For example linking the MOP agonist oxymorphone to the DOP antagonist naltrindole produces a MOP/DOP bivalent ligand that should produce analgesia with reduced tolerance. The type of response/selectivity produced depends on the pharmacophore combination (e.g. oxymorphone and naltrindole as above) and the space between them. Production and evaluation of bivalent ligands is an emerging field in drug design and for anaesthesia, analgesics that are designed not to be highly selective morphine-like (MOP) ligands represents a new avenue for the production of useful drugs for chronic (and in particular cancer) pain.