Systemic local anaesthetic toxicity from continuous thoracic paravertebral block.

Continuous paravertebral block is commonly used for post-thoracotomy analgesia and compares favourably with other systemic and regional methods with regard to safety and efficacy. No major complications of continuous paravertebral block for post-thoracotomy analgesia have been reported previously. We report here a case of systemic local anaesthetic toxicity from continuous paravertebral block administration after thoracotomy and lobectomy leading to seizure, aspiration, and ultimately, death. Potential contributing factors in this case included small patient size, concomitant antifungal therapy, extensive surgical disruption of the pleurae, and inappropriate paravertebral bolus administration. Postoperative delirium was a diagnostic confounder. We discuss the potential causes and means of avoiding similar complications in the future.

A prospective, multicentre, observational cohort study of analgesia and outcome after pneumonectomy.

BACKGROUND: Meta-analysis and systematic reviews of epidural compared with paravertebral blockade analgesia techniques for thoracotomy conclude that although the analgesia is comparable, paravertebral blockade has a better short-term side-effect profile. However, reduction in major complications including mortality has not been proven. METHODS: The UK pneumonectomy study was a prospective observational cohort study in which all UK thoracic surgical centres were invited to participate. Data presented here relate to the mode of analgesia and outcome. Data were analysed for 312 patients having pneumonectomy at 24 UK thoracic surgical centres in 2005. The primary endpoint was a major complication. RESULTS: The most common type of analgesia used was epidural (61.1%) followed by paravertebral infusion (31%). Epidural catheter use was associated with major complications (odds ratio 2.2, 95% confidence interval 1.1-3.8; P=0.02) by stepwise logistic regression analysis. CONCLUSIONS: An increased incidence of clinically important major post-pneumonectomy complications was associated with thoracic epidural compared with paravertebral blockade analgesia. However, this study is unable to provide robust evidence to change clinical practice for a better clinical outcome. A large multicentre randomized controlled trial is now needed to compare the efficacy, complications, and cost-effectiveness of epidural and paravertebral blockade analgesia after major lung resection with the primary outcome of clinically important major morbidity.

Pre-emptive effect of multimodal analgesia in thoracic surgery.

Thirty subjects undergoing posterolateral thoracotomy were allocated randomly to receive one of two analgesic regimens: group Pre received i.v. morphine, i.m. diclofenac and intercostal nerve blocks from T2 to T11, 20 min before operation and placebo injections after operation. Group Post received placebo injections before operation, and i.v. morphine, i.m. diclofenac and intercostal nerve blocks from T2 to T11 at the end of surgery, before discontinuation of anaesthesia. Visual analogue pain scores, extent and duration of intercostal nerve block, analgesic consumption and complications were assessed during the postoperative period by a single blinded observer. Subjects were followed-up for a minimum of 12 months to determine the incidence of post-thoracotomy pain syndrome. During the first 48 h after operation there were lower pain scores in group Pre when taking a vital capacity breath but there were no significant differences between the groups in any other measure. The effects of pre-emptive analgesia given before surgery appeared to be relatively modest in terms of analgesia, analgesic consumption and long-term outcome and were of limited clinical significance.

Rationalising ophthalmic admissions.

A new ophthalmic admission document has been devised which integrates existing medical and nursing input promoting a more consistent and concise assessment of the patient.

Ketorolac as a component of balanced analgesia after thoracotomy.

Ketorolac 10 mg or 30 mg i.m., 6 hourly or placebo was given to 75 patients who had undergone thoracotomy, in a randomized double-blind study. All subjects were given intercostal nerve blocks with bupivacaine and had access to i.v. patient-controlled morphine. I.m. ketorolac improved the success rate of the analgesic regimen, with fewer patients withdrawing from the study because of inadequate pain relief.

The alkalinisation of bupivacaine for intercostal nerve blockade.

A double-blind randomised study was performed to investigate the effect of pH adjustment of bupivacaine, with adrenaline 1:200,000, on the duration of block and pain relief after intercostal nerve blockade following thoracotomy. One group (n = 10) received bupivacaine with adrenaline 1:200,000 (pH = 4.1) and the other (n = 10) received alkalinised bupivacaine with adrenaline 1:200,000 (pH = 6.9). There was no significant difference in block duration (mean 23.9 and 26.4 hours respectively) visual analogue pain scores or morphine usage. Patients were more likely to have a block during the first 12 hours if they received alkalinised bupivacaine (p less than 0.01, Chi-squared test). A progressive regression of block, not previously described, was observed, explicable by means of spread of local anaesthesia to adjacent intercostal nerves. Alkalinisation of bupivacaine with adrenaline for intercostal nerve blockade has little clinical benefit.

Acute toxicity of ropivacaine compared with that of bupivacaine.

The acute central nervous and cardiovascular effects of the local anesthetics ropivacaine and bupivacaine were compared in 12 volunteers in a randomized double-blind manner with use of intravenous infusions at a rate of 10 mg/min up to a maximal dose of 150 mg. The volunteers were all healthy men. They were familiarized with the central nervous system (CNS) toxic effects of local anesthetics by receiving a preliminary intravenous injection of lidocaine. The infusions of ropivacaine and bupivacaine were given not less than 7 days apart. CNS toxicity was identified by the CNS symptoms and the volunteers were told to request that the infusion be stopped when they felt definite but not severe symptoms of toxicity such as numbness of the mouth, lightheadedness, and tinnitus. In the absence of definite symptoms, the infusion was stopped after 150 mg had been given. Cardiovascular system (CVS) changes in conductivity and myocardial contractility were monitored using an interpretive electrocardiograph (which measured PR interval, QRS duration, and QT interval corrected for heart rate) and echocardiography (which measured left ventricular dimensions from which stroke volume and ejection fraction were calculated). Ropivacaine caused less CNS symptoms and was at least 25% less toxic than bupivacaine in regard to the dose tolerated. Both drugs increased heart rate and arterial pressure. Stroke volume and ejection fraction were reduced. There was no change in cardiac output. Although both drugs caused evidence of depression of conductivity and contractility, these appeared at lower dosage and lower plasma concentrations with bupivacaine than with ropivacaine.(ABSTRACT TRUNCATED AT 250 WORDS)

Anaesthetic management of the patient with a permanent pacemaker.

Over 25,000 people in Britain now have pacemakers, and the number is increasing steadily. Anaesthetists encounter patients with pacemakers regularly. Knowledge about the increasingly wide range of pacemakers available is necessary to ensure safe management of these patients, many of whom are frail and elderly. This review outlines the indications for permanent pacing, the types of pacemaker used and the assessment and management of pacemaker patients for anaesthesia.

Extradural block with bupivacaine: influence of dose, volume, concentration and patient characteristics.

In a randomized, double-blind study the influences of the characteristics of both solution (dose, volume, concentration) and patient (age, weight, height, body mass index) on the development of extradural blockade produced by a low lumbar injection of bupivacaine were investigated. Thirty patients aged between 20 and 50 yr received one of three solutions (groups I-III, respectively): 0.75% 10 ml (75 mg); 0.5% 15 ml (75 mg); 0.75% 15 ml (112.5 mg). A further 20 patients older than 50 yr received 0.75% bupivacaine 10 ml (group IV, n = 10) or 15 ml (group V, n = 10). The number of segments blocked at maximal extent of block was virtually the same in each group: group I (0.75% 10 ml) 13.3 (SD 1.4); group II (0.5% 15 ml) 14.1 (2.9); group III (0.75% 15 ml) 13.8 (2.2); group IV (0.75% 10 ml) 14.2 (2.1); group V (0.75% 15 ml) 16.7 (3.1). The larger dose of bupivacaine (112.5 mg) produced the fastest onset and longest duration of block. Onset and recovery intervals were similar with 0.75% and 0.5% solutions when administered at the same dose (75 mg in 10 ml or 15 ml). There was no correlation between the level of block and the age, weight and height of the patient. In patients who received 15-ml injections, there was a positive association between the upper level of block and body mass index.

Effects of posture and baricity on spinal anaesthesia with 0.5% bupivacaine 5 ml. A double-blind study.

In four groups of 10 patients, 0.5% bupivacaine 5 ml was used in spinal anaesthesia for gynaecological surgery. Group 1 received plain solution in the sitting position, group 2 plain solution in the lateral position, group 3 hyperbaric solution in the sitting position and group 4 hyperbaric solution in the lateral position. All patients were returned to the horizontal supine position, the sitting subjects 2 min after, and the lateral subjects immediately after, spinal injection. In each group the mean height of block was to the mid-thoracic segments, but there was no significant difference between the groups. There was, however, considerable scatter within each group. Posture had some effect on the speed of onset of the analgesia, but no significant effect on the final outcome. The use of 0.5% bupivacaine as a test dose in extradural blockade is discussed.

Effect of extradural bupivacaine or i.v. diamorphine on calf blood flow in patients after surgery.

Strain gauge venous occlusion plethysmography was used to measure arterial flow, venous capacity and maximum venous outflow in the calves of seven patients undergoing gynaecological surgery. Plethysmography was performed before surgery, before, and for 30 min after, the extradural injection of 0.5% bupivacaine. On the morning after surgery, 0.5% bupivacaine was injected extradurally and plethysmography performed. With regression of the extradural blockade and the re-emergence of pain, analgesia was produced with diamorphine i.v. and plethysmography repeated. Control measurements were also made. Compared with a mean control value of 100% (3.4 ml dl-1 min-1) calf arterial flow increased from 160% to 285% after the preoperative extradural blockade, and from 123% to 191% following the postoperative analgesic extradural blockade, but there was no significant change when pain was relieved after i.v. diamorphine. Mean arterial pressure changed insignificantly after all the injections. No significant changes were measured in venous capacity or maximum venous outflow.

Selective effects of ECT on hypothalamic-pituitary activity.

The hypothesis that ECT produces selective effects on hypothalamic-pituitary activity was investigated by determining the effect of ECT on pituitary hormone release in nine depressed patients. After ECT there were massive and rapid increases in the plasma concentrations of nicotine- and oestrogen-stimulated neurophysin (NSN and ESN), prolactin (PRL) and adrenocorticotropin (ACTH), smaller increases in plasma luteinizing hormone (LH) and cortisol, a significant decrease in plasma growth hormone (GH) concentration but no change in plasma thyrotropin (TSH). There was significant attenuation of PRL responses with repeated ECT. The hormonal responses to ECT cannot simply be attributed to stress, since a similar pattern of increases in plasma hormone concentrations did not occur in psychologically normal patients in whom plasma hormone concentrations were measured during induction of anaesthesia and abdominal incision for cholecystectomy. Analysis of these hormonal responses in terms of the knowledge available on the neurotransmitter control of pituitary hormone release suggests that some of these hormonal responses to ECT may be mediated by the activation of serotonergic neurones, while others are probably due to direct stimulation of the neuroendocrine neurones themselves.