Biomedical subjects
I D Conacher
Publications and source records attributed to I D Conacher.
Dynamic hyperinflation--the anaesthetist applying a tourniquet to the right heart.
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Transoesophageal echocardiography in the management of whole lung lavage.
The effects of two lung ventilation, one lung ventilation and alveolar lavage on right ventricular mechanics in a patient have been observed using transoesophageal echocardiography (TOE). Alveolar lavage resulted in additional stresses to those of one lung ventilation (OLV) and the point when these were noted to be resulting in right ventricular changes was used as the signal to terminate the filling phase of a cycle of alveolar lavage. A significant increase in right ventricle afterload occurred on starting OLV. The response to lung lavage was biphasic, initially a further increase in afterload followed by a reduction in preload. Because there was rapid adaptation to these changes, it was felt appropriate to perform sequential lung lavage during the same anaesthetic. In similar circumstances where pulmonary vascular resistance is changed, information obtained from TOE may be used to guide therapy.
The successful introduction of general anaesthesia.
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Anaesthesia for the surgery of emphysema.
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Central airway compression. Anaesthetic and intensive care consequences.
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'Chicane-like' airway as a complication of lingual tonsils.
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Amylene, a blemish on Snow?
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Pathognomonic pulse oximetry paradox.
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Intrathecal fentanyl for post-thoracotomy pain.
This double-blind, placebo-controlled study investigated the efficacy of intermittent doses of intrathecal fentanyl in 30 patients undergoing thoracotomy. They were allocated randomly to three groups, two of which had microspinal catheters inserted into the lumbar subarachnoid space at the end of surgery; the third group acted as a control. Intrathecal fentanyl or 0.9% saline was administered through the catheters and all patients received morphine using a patient-controlled analgesia (PCA) system. Pain scores, morphine consumption and peak expiratory flow rates (PEFR) were recorded on an hourly basis. Intrathecal fentanyl resulted in a faster onset of analgesia (mean visual analogue scale (VAS) score at 1 h = 0.9 compared with 6.3 (95% confidence intervals for the difference -6.8, -4.0) for the other groups; P < 0.001) and significantly lower pain scores at rest, on cough and on movement. PEFR values were consistently higher in the intrathecal fentanyl group. There were no cases of early or delayed respiratory depression.
Prolonged interval jet ventilation. An alternative ventilation technique for patients with problematic cardiopulmonary pathophysiology.
The initial clinical experience of using a technique of prolonged interval jet ventilation is reported. Periodic pulses, of from three to nine breaths, were delivered in rapid sequence from a jet ventilator during one-lung ventilation. The expiration phase was free to atmosphere, without added artificial expiratory assist or resistance, and of from 30 to 50 s duration before delivery of the next pulse of jet ventilation. The aim of the technique was to evaluate during anaesthesia the practicalities of securing a prolonged period during which intrathoracic pressure is low and hence optimal for venous return and deflation of pathological pulmonary regions with long time constants. The system used is flexible enough to allow for conventional positive pressure techniques to be applied if necessary. As the gas delivery was of oxygen of high concentration, episodes of hypoxaemia were minimal in this group of high risk patients and due to technical rather than physiological causes. The delivery of a minute volume adequate to prevent hypercapnia was not always possible and the technique may be contraindicated in those conditions in which a raised carbon dioxide concentration is disadvantageous.
Paravertebral blockade. Failure rate and complications.
The failure rate and complications were studied prospectively in 367 paediatric and adult patients who had received a thoracic or lumbar paravertebral block. The overall failure rate was 10.1%; adults 10.7%; children 6.2%. The frequency of complications were: hypotension: 4.6%; vascular puncture: 3.8%; pleural puncture: 1.1%; pneumothorax: 0.5%. Since these results are similar to those found with alternative methods, e.g. epidural, intrapleural and intercostal blocks, paravertebral block can be recommended as an effective, safe technique for unilateral analgesia in both adults and children.
Videothoracoscopic operation for secondary spontaneous pneumothorax.
Thoracotomy for the management of a secondary spontaneous pneumothorax is associated with a high perioperative risk related to the presence of underlying lung disease. Videothoracoscopy offers the potential therapeutic benefits of a minimally invasive approach. We report on a series of 22 patients (19 men and 3 women) with a mean age of 70 years (range, 46 to 92 years) who underwent videothoracoscopic surgical procedures for the treatment of secondary spontaneous pneumothorax. All patients had emphysema; their mean preoperative forced expiratory volume in 1 second was 48% of predicted and their mean forced vital capacity was 64% of predicted. Eighteen patients presented with a persistent air leak and their mean preoperative hospital stay was 18 days (range, 6 to 40 days). Pleurectomy was performed in all 22 patients, together with bullectomy in 20 patients, with a mean overall operating time of 57 minutes (range, 24 to 90 minutes). General anesthesia was used in each patient. Single-lung ventilation, used in the majority, was found to be superior to high-frequency jet ventilation. The postoperative analgesic requirement was minimal (average, 15 mg of morphine in the first 12 hours), and no patient required reventilation. A revisional thoracotomy for the management of a persistent postoperative air leak was required in 4 patients, one of whom subsequently died in respiratory failure. The mean postoperative stay was 9 days (range, 3 to 26 days). At a mean follow-up of 8.6 months (range, 2 to 15 months), no pneumothorax had recurred.(ABSTRACT TRUNCATED AT 250 WORDS)
Videothoracoscopic pleurectomy after contralateral single-lung transplantation.
Left single-lung transplantation in a 46-year-old man was complicated by spontaneous contralateral pneumothorax during the immediate postoperative period. This persisted despite chemical pleurodesis, but was successfully treated by videothoracoscopic pleurectomy, with minimal effect on respiratory function. The increasing use of single-lung transplantation for emphysema may increase the incidence of such problems from the native lung. Minimally invasive techniques may be of great clinical benefit in this situation.
Mixed venous oxygen saturation during lung transplantation.
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Carbon dioxide laser bronchoscopy--a review of its use in the treatment of malignant tracheobronchial tumours in 142 patients.
We report our experience over an 8-yr period, 1984-1991, of the use of the carbon dioxide (CO2) laser in the treatment of otherwise inoperable malignant tracheobronchial lesions. In that period 142 patients (84 male, 58 female; median age 63 years) underwent 278 procedures. The trachea was the site of treatment in 44 patients, the carina in nine, a main bronchus in 80 and a lobar bronchus in nine. All resections were performed under general anaesthesia via a rigid bronchoscope. Symptomatic relief was obtained in 103 of the 116 patients whose main complaint was dyspnoea. Overall there was a mean improvement in forced expiratory volume in 1 s (FEV1) of 27%, in peak expiratory flow (PEF) of 22% and in forced vital capacity (FVC) of 7%. Most improvement in FEV1 and PEF was obtained by the treatment of tracheal lesions. Three patients died within 24 h of surgery and 30 day mortality was 18%. At a mean follow-up of 18.3 months the mean post-laser survival is 5 months. While the CO2 laser has limitations in the treatment of distal tumours when compared to the neodymium/yttrium aluminium garnet (Nd:YAG) laser, there was no higher incidence of complications. We have found CO2 laser bronchoscopy to be an effective palliation of inoperable malignant tumours particularly of the trachea and main bronchi.
Video-assisted thoracoscopic placement of paravertebral catheters: a technique for postoperative analgesia for bilateral thoracoscopic surgery.
Paravertebral catheters were placed bilaterally through a Tuohy needle under direct video control in a patient undergoing video-assisted thoracoscopic (VAT) surgery for recurrent, bilateral pneumothoraces. Postoperative analgesia was produced by infusing bupivacaine through the catheters. This provided good analgesia. VAT placement of paravertebral catheters is easily accomplished and may be a part of the surgical procedure.
Pleural effusions and anaesthesia.
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