Should nitrous oxide be discontinued before desflurane after anaesthesia with desflurane/N2O?

Background : The appearance of hypoxaemia immediately after anaesthesia with nitrous oxide may be partially explained by diffusion hypoxia. This study was undertaken to evaluate circulatory and respiratory variables during emergence after desflurane/nitrous oxide anaesthesia, and whether there are any differences depending on which gas is discontinued first. Methods : 20 patients were studied after gynaecological laparoscopic surgery. The depth of anaesthesia was reduced 10 min prior to the emergence by stopping the administration of one of the two inhalational agents. Desflurane was discontinued first in Group 1, nitrous oxide in Group 2. Ventilation was controlled with E'C0₂ maintained at 5% until the administration of the second anaesthetic gas was discontinued. Thereafter, the patients breathed spontaneously. Results : The PaC0₂ at which the respiratory drive reappeared after controlled normoventilation was similar in both groups, 6.1–6.5 kPa, and extubation was performed after 10–11 min. At extubarion, the end–tidal C0₂ and total MAC were similar in the groups, about 6.2 vol% and 0.16, respectively. Mean arterial blood pressure was significantly higher in Group 1. The cardiac output increased in both groups from about 6 1/min at the conclusion of anaesthesia to 9.0 and 7.6 1/min at 15 min in the recovery period. End–tidal O₂ decreased and CO₂ increased in both groups during the first 10 min in the recovery period. pH was reduced at 15 and 30 min in both groups. Conclusion : Irrespective of which agent was discontinued first, there was an increase in cardiac output, decrease in oxygenation and a modest acidosis in the first 30–min recovery period. The only significant difference between the groups was in mean arterial blood pressure in the early emergence phase with a greater MAP when N₂O had been used until the conclusion of anaesthesia.     

Angioedema due to angiotensin-converting enzyme inhibitor use: Radiographic findings in 3 patients

Angioedema of the oropharynx and hypopharynx due to oral angiotensin-converting enzyme (ACE) inhibitors is a potentially life-threatening event and has not been well described in the radiology literature. A retrospective review of the clinical and radiologic findings in three patients with angioedema due to ACE inhibitor use was performed.Our subgroup of patients treated with ACE inhibitors presented with varying degrees of dysphagia, dyspnea, and facial swelling. Plain radiographic findings included enlargement of the epiglottis, aryepiglottic folds, and prevertebral and submental soft tissue. Computed tomography confirmed extensive retropharyngeal and subcutaneous edema. Clinical symptoms resolved in each case in 24–48 hours with cessation of the ACE inhibitor and concomitant steriod therapy.Our cases demonstrate the typical clinical and radiographic presentation of neck angioedema in the setting of ACE inhibitor use. As ACE inhibitors are increasingly being used as first-line agents in the treatment of hypertension, we caution that neck angioedema may be encountered with increased frequency in adults. Early recognition and immediate intervention result in rapid resolution of this potentially life-threatening event.     

The first mechanism-based inactivators for angiotensin-converting enzyme.

The first example of mechanism-based inactivation of angiotensin-converting enzyme (ACE) is described for N-[N-(cyanoacetyl)-L-phenylalanyl]-L-phenylalanine (compound 1). It is proposed that an ACE-mediated deprotonation of 1 unmasks a ketenimine intermediate, which traps an active-site nucleophile, and hence irreversibly modifies the enzyme. In competition with the inactivation reaction, ACE also hydrolyzes 1 with a partition ratio of 8300 (i.e., kcat/kinact). Since the corresponding keto analogue, N-[(R)-2-benzyl-5-cyano-4-oxopentanyl]-L-phenylalanine (compound 4), does not inactivate the enzyme, it is suggested that the NH in compound 1 is critical for the proper active-site anchoring of the inhibitor for the inactivation process to take place.     

Combined radiotherapy and surgery in the treatment of neck node metastases from squamous cell carcinoma of the head and neck.

A prospectively recorded series of 107 patients with clinical neck node metastases from head and neck squamous cell carcinomas, treated in 1983-1988, and with initial local control, is evaluated. Eighty-eight patients received preoperative, and were operated 4-6 weeks after radiotherapy, and 19 received postoperative radiotherapy. Forty-four of the neck specimens in the preoperatively treated patients showed vital tumor tissue, 7 with positive and 37 with negative resection margins. Nine of the latter 37 patients died due to regional recurrence. Twenty-three of the preoperatively treated patients had no palpable residual tumor following radiotherapy, but histological examination showed vital tumor tissue in five, of whom two had N1 neck disease. The overall regional failure rate was 19%. Eleven patients (10%) died from local recurrence and 11 from distant metastases. Forty-one patients (38%) are alive without evidence of disease and three (3%) alive with disease (mean observation time 30 months). Combined treatment is recommended for all cases of neck node metastases.     

Department of Palliative Care in Bratislava and the development of the palliative care movement in Slovakia

 Slovakia is a country with no tradition of home care services and a long history of regarding death and dying as taboos and therefore institutionalising them. Increased attention to palliative care issues has resulted in some important changes, to the benefit of patients in need of palliative care. These include general availability of oral slow-release forms of strong opioids (cost completely reimbursed by the insurance companies), a developing network of home care agencies, and increased attention to the needs of palliative patients, especially among oncologists and pain specialists. In February 1995 the Department of Palliative Care was established within the National Cancer Institute in Bratislava. It has 19 in-patient beds and also an out-patient clinic. Although the primary goal is the improvement of the quality of life, several approaches that can prolong life without worsening its quality are also used. These include laser destruction of intraluminal gastrointestinal tumours, insertion of intraluminal stents, brachyradiotherapy, pleurodeses, percutaneous gastrostomy, percutaneous nephrostomy, palliative chemotherapy, treatment of hypercalcaemia. In 1995 the Palliative Care Section of the Association for Study and Treatment of Pain was established, as was thefirst Hospice Foundation.     

Genes in idiopathic calcium oxalate stone disease

An examination of the urinary excretions of 101 normal subjects indicated that the major genetic influence on calcium excretion is a codominant pair of alleles giving rise to three phenotypes, low, intermediate and high (hypercalciuric) excretors. This inference was based on variance, Hardy-Weinberg and segregation analyses. Similar independent gene pairs also appear to influence oxalate and citrate excretion, A 3-locus Hardy-einberg table using estimates of gene frequencies derived from the study of normals suggests that only 3 or 4 leading genes are involved in oxalate stone disease. Strong candidate genes identified from molecular and physiological studies cannot be proposed at present, but it is assumed that they influence the transport of these ions in either the intestine, kidney or both organs. The identification of the genes involved should be facilitated by the reduction of dietary influences on urinary excretions through the use of formula diets.     

Osteoarthritis and recurrences after Putti-Platt and Eden-Hybbinette operations for recurrent dislocation of the shoulder

Summary. Thirty-five patients who had operations for recurrent anterior dislocation of the shoulder were reviewed, with a further 26 answering a questionnaire; the results were not as good as reported by others. The mean follow up was 26.9 years. Ten out of 43 patients had recurrent dislocations after the Putti-Platt and 6 out of 18 after the Eden-Hybbinette operation. Osteoarthritis developed in 15 shoulders of 26 patients who were followed-up after the former procedure and in 8 out of 9 shoulders after the latter. These sequelae depend on the age at the first dislocation rather than the number of dislocations. The overall satisfaction rate was acceptable for both procedures.

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Résumé. Notre étude à long terme (sur 61 patients, 35 suivis avec une moyenne de 26,9 ans) montre que les résultats des opérations de Putti-Platt et Eden-Hybbinette pour luxation récidivante de l’épaule ne sont pas, en considérant les récidives et le développement de l’arthrose, aussi bons que ceux rapportés dans la littérature [5, 8, 14, 18]. Dans notre série, 10 patients sur 43 ont eu une luxation récidivante après une intervention de Putti-Platt et 6 sur 18 après une opération de Eden-Hybbinette. Une omarthrose était présente chez 8 sur 9 patients du groupe Eden-Hybbinette et chez 15 sur 26 patients du groupe Putti-Platt. Nous pensons que le développement de l’omarthrose dépend plus de l’age du patient lors de la première luxation que du nombre de luxation avant l’intervention. Cependant, le taux de succès après une période d’observation moyenne de 26,9 ans était acceptable pour les 2 types de traitement.

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Accepted: 10 May 1996     

A study of mixing conditions during nitric oxide administration using simultaneous fast response chemiluminescence and capnography

We have evaluated the mixing properties of nitric oxide in inspired gases for five different administration techniques. Nitric oxide and carbon dioxide were delivered to the ventilator system before the ventilator or after the ventilator as a continuous flow, either directly into the inspiratory limb or into a mixing chamber positioned in the inspiratory limb. Both gases were delivered as above but synchronized with inspiration. Mixing conditions were evaluated using fast response chemiluminescence for nitric oxide and capnography for carbon dioxide analysis. Administration of nitric oxide and carbon dioxide directly into the inspiratory limb as a continuous flow or with a magnetic valve-controlled synchronized flow resulted in peak concentrations of 236% and 220%, respectively, of expected values. The use of a mixing chamber reduced these values to 104% and 102%, respectively. Administration of nitric oxide as a continuous flow into the tubing of an intermittent flow ventilator resulted in highly fluctuating inspiratory peak concentrations, which could be avoided with a mixing chamber.      

Effects of Clodronate on Cortical and Trabecular Bone in Ovariectomized Rats on a Low Calcium Diet

The aim of this study was to evaluate the contribution of a low calcium diet to the cortical and trabecular osteoporosis seen in ovariectomized rats after 7 weeks on a low calcium diet and to investigate the effects of the bisphosphonate clodronate on this development of osteoporosis. Thirty-six mature, female Wistar rats were randomized into four groups: Ovx−B (bisphosphonate) and Ovx−C (control) were ovariectomized, and Sham−Ca (low calcium) and Sham+Ca (normal calcium) were sham operated. The first three groups were fed a low calcium diet (0.01%) and Sham+Ca normal rat chow (Ca 1.1%). The Ovx−B received 10 mg/kg s.c. clodronate daily for nine weeks, and Ovx−C, Sham−Ca, and Sham+Ca received the same volumes of saline. Bone mineral turnover measured as ⁸⁵Sr-uptake was increased in all low calcium groups compared to Sham+Ca. The Sham+Ca femora had higher dry weight and ash weight than the other groups, and Ovx−C had higher dry weight compared with Ovx−B and Sham−Ca. Calcium content was lower in both Ovx groups compared to both Sham groups. Magnesium was lower in all groups compared to Sham+Ca and higher in Ovx−B compared with Ovx−C. In the femoral shaft, Sham+Ca had significantly higher ultimate bending moment, energy absorption, and deflection compared to the other three groups. Ultimate bending moment was higher in Sham−Ca than in Ovx−C. Stiffness was increased in both Sham+Ca and Ovx−B compared to Ovx−C. The maximum stress in the femoral midshaft was higher in Sham+Ca than in the other groups, and higher in Ovx−B than in Ovx−C. Histomorphometry showed increased medullary area in all low calcium groups compared to Sham+Ca and larger cortical area in Sham+Ca and Ovx−B compared to Ovx−C. Compared to Sham+Ca the trabecular bone volume was decreased to 30% in Sham−Ca and to 9% in Ovx−C, but was unchanged in Ovx−B. The low calcium diet generally increased bone mineral turnover and reduced the tibial bone volume. Femoral changes led to a reduction of cortical fracture strength and maximal stress. Ovariectomy in addition to a low calcium diet reduced femoral strength even more. Daily injections of clodronate to ovariectomized rats on a low calcium diet increased femoral shaft stiffness and maximum stress, and clodronate preserved both trabecular and cortical tibial bone volume completely. Received: 11 June 1996 / Accepted: 5 March 1997