Brief review: Angiotensin converting enzyme inhibitors and angioedema: anesthetic implications

PURPOSE: Angiotensin converting enzyme inhibitors (ACEIs) are a group of drugs used to treat hypertension and heart failure, with additional benefits, such as cardiovascular and renal protection, in patients with diabetes. However, angioedema as a complication of ACEI therapy is under-recognized. As there are important implications for anesthesiologists and emergency medicine physicians, a review was undertaken to document the scope of the problem of ACEI-induced angioedema.. METHODS: A review of the published literature (identified by searching Medline, EMBASE and CINAHL) was undertaken, addressing the clinical uses of ACEIs and the incidence, risk factors, pathophysiology, clinical presentation and management of angioedema associated with the use of these drugs. PRINCIPAL FINDINGS: The incidence of ACEI related angioedema has increased from 0.1-0.2% to 1% over the last decade. Patients who are receiving ACEIs are predisposed to developing angioedema which may be triggered by trauma, airway instrumentation, infection, and irritant fumes, particularly in those who are at increased risk. Cases of acute facial and airway oedema, due to ACEI drug administration, may be misdiagnosed as an anaphylactic reaction, and the association with ACEIs may be ignored. Some cases of intraoperative and postoperative airway edema may be precipitated by airway instrumentation in patients receiving ACEI drugs. The severity of airway compromise ranges from mild facial edema to severe laryngeal or subglottic edema which may prove life-threatening. CONCLUSION: In view of the widespread clinical indications and ever-increasing use of ACEI drugs, the potentially life-threatening adverse reaction of ACEI-associated angioedema, and its treatment, must be recognized by anesthesiologists and all clinicians involved in airway management.     

Allografts of CNS tissue possess a blood-brain barrier. II. Angiogenesis in solid tissue and cell suspension grafts

Angiogenesis and patency of blood vessels were analyzed qualitatively in solid CNS and peripheral tissue syngeneic, allogeneic, and xenogeneic grafts and in individual cell suspension grafts of astrocytes, fibroblasts, PC12, and three additional tumor cell lines placed intracerebrally in adult host mice. Postgrafting survival times were 1 day through 4 weeks. The patency of graft vessels was determined in sections from immersion-fixed tissues incubated to reveal the endogenous peroxidase activity of host red cells trapped within the lumen of blood vessels. Additionally, horseradish peroxidase (HRP) was administered intravenously to live hosts; HRP labels host brain and graft vessels on the luminal surface and reveals the presence or absence of a blood-brain barrier (BBB) within the grafts. The origins of blood vessels supplying solid tissue xenografts were identified immunohistochemically with primary antibodies against host (athymic AKR mice) and donor (fetal Lewis rats) major histocompatibility complex (MHC) class I. Blood vessels supplying solid CNS grafts at 1-7 days post-transplantation were identified ultrastructurally and possessed interendothelial tight junctional complexes; however, they were not perfused with either host blood or blood-borne HRP prior to 8 days. Graft vessels at 10 days were outlined consistently by peroxidase-positive red cells in immersion-fixed material and labeled with blood-borne HRP. These vessels provided a BBB to the circulating HRP and exhibited interendothelial tight junctions. Evidence of angiogenesis within solid anterior pituitary grafts and the variety of cell suspension grafts was obtained prior to 3 days post-transplantation in immersion-fixed preparations; the vessels, with the notable exception of those supplying astrocyte cell suspensions, failed to present a BBB to blood-borne peroxidase. Endothelia in the solid pituitary allografts and the PC12 cell grafts were highly fenestrated and exhibited open interendothelial junctions; those in the tumor and fibroblast cell grafts, for the most part, appeared nonfenestrated, and many possessed open interendothelial junctional complexes. Immunostaining for host and donor MHC class I revealed that donor blood vessels predominate over host vessels in CNS xenografts and supply pituitary xenografts exclusively; in both preparations, donor vessels were not identified within the host CNS. Because cell suspension grafts were derived from endothelia-free preparations grown in culture, blood vessels supplying these grafts were necessarily of host CNS origin and manifested a morphological transformation from a BBB to a non-BBB endothelium. The data suggest that angiogenesis in solid CNS grafts placed into the adult host CNS, compared to similarly placed solid peripheral tissue/cell suspension grafts, is not rapid.(ABSTRACT TRUNCATED AT 400 WORDS)     

Renal transplantation performed across a positive crossmatch: A single centre experience

The importance of certain positive crossmatches (CM⁺) in kidney transplantation remains controversial. Fifty consecutive kidney transplants were performed across a CM⁺ between Jan. 1990 – April 1994. In 19 cases there was an isolated B-cell CM⁺ (Group I), in 24 an historic T-cell IgM CM⁺ (Group II) and in 7 an historic T-cell IgG CM⁺ (Group III). Comparing groups I:II:III: early acute rejection affected 32%, 42%, 57% of grafts; mean serum creatinine at 3 months was 166, 150, 229 umol/l (p<0.05); 1 yr graft survival was 95 per cent, 96 per cent, 71 per cent (p=0.09). In group III both graft losses were in the setting of an additional current B-cell CM⁺. Conclusions: Transplantation performed in either the presence of an isolated B-cell CM⁺ or in the presence of an historic T-cell IgM CM⁺ was associated with acceptable outcomes at 1 yr. An historic T-cell IgG CM⁺ was confirmed as a contraindication to transplantation in most circumstances, especially when coupled with a current B-cell CM⁺.     

Homozygosity of the short arm of chromosome 17 in cervical carcinoma.

We have determined the frequency of heterozygosity of the short arm of chromosome 17 in 20 cervical tumours using the highly polymorphic probe pYNZ22. Only 25% of the tumours were heterozygous at this locus. This is significantly lower than the level of 86% heterozygosity for this locus in the general population indicating that loss of one allele occurs in cervical cancer. Heterozygosity for a locus on the long arm of the same chromosome showed no significant difference between the tumours and the general population indicating that genetic loss was confined to the short arm of the chromosome. The analysis of premalignant lesions showed 70% of patients were heterozygous suggesting that loss of material from the short arm of chromosome 17 took place at a late stage in tumour development. This report confirms predictions made from previous karyotypic analysis and is the first indication of allele loss on the short arm of chromosome 17 in cervical cancer.     

Nitric oxide synthase inhibitor,nitro-iminoethyl-L-ornithine,reduces ischemia-reperfusion injury in rabbit skeletal muscle

Nitric oxide (NO), originally identified as the mediator of endothelial-dependent relaxation of vascular smooth muscle, is now known to also have cytotoxic effects under certain conditions. Thus, we have investigated the effects of inhibition of NO synthesis on ischemia/reperfusion injury in the rabbit rectus femoris muscle. Three and a half hours of ischemia and 24 hours of reperfusion resulted in a 56% loss of viability. In muscles receiving an infusion of the nitric oxide synthase inhibitor, L-NIO (30 μM), the loss of viability was reduced to 15%. Post-ischemic blood flow was increased in muscles receiving a saline infusion, whereas there was a marked decrease in blood flow for at least the first 60 minutes of reperfusion in muscles treated with L-NIO (30 μM). The increase in myeloperoxidase levels (indicative of neutrophil accumulation) following 24 hours of reperfusion was attenuated with L-NIO infusion by approximately 50% and the reperfusion-induced edema was also attenuated in L-NIO treated muscle. These findings suggest that endogenous NO production during ischemia/reperfusion injury may be deleterious to muscle survival. © 1994 Wiley-Liss, Inc.     

A comparison of respiratory function in divers breathing with a mouthpiece or a full face mask

A comparison was made of respiratory function in submersed divers breathing with either a mouthpiece or a full face mask while exposed to varying depths (15 and 190 fsw), exercise loads (0-175 W), and static lung loads (0 and -20 cmH2O). The two types of breathing equipment were designed to be identical in terms of functional dead space volume and resistance to gas flow. When compared with data from experiments utilizing a full face mask, use of a mouthpiece caused a modest fall in expired minute volume at both depths. The majority of this decline may have been the consequence of a decrease in dead space ventilation brought about by the elimination of simultaneous nose breathing and mouth breathing. Alveolar ventilation and PETCO2 were not significantly influenced by the use of a mouthpiece, regardless of depth, workload, or static lung load. With both types of breathing gear episodes of dyspnea were infrequent during experiments with a static lung load of 0 cmH2O. Therefore, if a neutral static lung load is maintained, the type of breathing gear used does not seem to be of consequence as far as dyspnea is concerned.