Volatile anaesthetics and cardioprotection – lessons from animal studies

Volatile anaesthetics emerged as important cardioprotective agents in both animal models of ischaemia/reperfusion injury and humans with coronary artery disease. Their administration before a prolonged ischaemic episode is known as anaesthetic preconditioning, whereas when given at the very onset of reperfusion, the strategy is termed anaesthetic postconditioning. Both types of anaesthetic conditioning reduce, albeit not to the same degree, the extent of myocardial injury. They share similar, albeit not identical, intracellular signal transduction pathways with their widely investigated counterparts, ischaemic pre‐ and postconditioning. Despite a wealth of preclinical evidence for cardioprotection for anaesthetic conditioning strategies, their translation into clinical therapy has been rather disappointing. This review highlights the major findings on the cardioprotective effects of volatile anaesthetics in experimental settings. It explores hypotheses that may explain the lack of efficacy observed in several past clinical studies paving the way for future preclinical and translational studies.     

Pediatric Power Wheelchairs: Evaluation of Function in the Home and School Environments

The purpose of this study was to compare the performance of four power wheelchairs when used by children to perform a variety of indoor activities. Eight boys and eight girls performed a series of 11 functional tasks when positioned in each of four different power wheelchairs reflecting different design classes. There were no significant differences for many of the dependent variables. However, the Everaid Turbo was significantly better for functional positioning at a standard kitchen table and at school desks and for accessing objects at different heights. By contrast the Invacare Jaguar was better for straight-line driving speed. Other findings include children's subjective impressions of the four power wheelchairs.     

Diameter Reduction of the Proximal Long Saphenous Vein after Ablation of a Distal Incompetent Tributary

In this study, we measured the diameter of the competent long saphenous vein proximally and distally to the anastomosis of an isolated incompetent tributary in 12 patients. Measurements were made both before and 30-45 days after surgical removal of the tributary. The preoperative diameter of the saphenous vein proximal to the anastomosis was greater than distally. The difference between proximal and distal to the tributary veins sections diminished from 1.59 mm to 0.39 mm (p = 0.0033) after surgical removal of the tributary alone. This phenomenon may be compared with other hemodynamic occurrences between the superficial and deep system. The incompetence of a tributary induces a proximal dilatation of the long saphenous vein. The isolated ablation of an insufficient tributary appears to be a useful measure to prevent degeneration of greater saphenous vein function as this procedure reduces the saphenous diameter.     

The effects of light emitting diode therapy following high intensity exercise

ObjectiveTo determine the effects of light emitting diode therapy (LEDT) irradiation on blood lactate concentration ([La]) clearance, peak power output and fatigue index (FI) following high intensity fatiguing exercise.DesignSingle-blinded randomised cross-over placebo controlled trial.SettingUniversity College Dublin, Institute for Sport and Health, Human performance laboratory.ParticipantsEighteen healthy male athletes were recruited from field-based sports (including soccer, hockey and rugby union) and participated in the present study.Main outcome measuresDependent variables were the peak power output elicited during the Wingate Anaerobic Test (WAnT), FI and [La] before and after each exercise. WAnT performance was measured prior to high intensity fatiguing exercise (Yo–Yo IR2), prior to LEDT or placebo, and following LEDT or placebo. [La] was measured at baseline, immediately after the Yo–Yo IR2, and in the 3rd, 9th, and 15th min following LEDT or placebo condition.ResultsNo significant group by treatment interactions were observed for any outcome measures (P > 0.05).ConclusionWe conclude that LEDT irradiation applied following high intensity exercise was not effective and has no immediate effect on [La] clearance, peak power and FI, and thus has no significant effect on muscle recovery in athletes at the intensity and irradiation parameters used in the present study. Further research using different parameters is required to determine how LEDT may contribute to post-exercise recovery.     

Duplex ultrasound scan findings two years after great saphenous vein radiofrequency endovenous obliteration

OBJECTIVE: To assess the clinical and duplex ultrasound scan findings in the groin and thigh 2 years after great saphenous vein (GSV) radiofrequency endovenous obliteration (RFO). METHODS: Sixty-three limbs in 56 patients with symptomatic varicose veins and GSV incompetence were treated with RFO, usually with adjunctive stab-avulsion phlebectomies, and examined at a median follow-up of 25 months, by using a color-coded, duplex sonography protocol that mandated views in at least two planes of the saphenofemoral junction (SFJ) and its tributaries and at three GSV levels in the thigh. RESULTS: The commonest duplex finding in the groin was an open, competent, SFJ with a < or =5-cm patent terminal GSV segment conducting prograde tributary flow through the SFJ (82%). Despite the presence of a total of 104 patent junctional tributaries, SFJ reflux was uncommon, affecting only five limbs. GSV truncal occlusion was observed in 90% of treated GSVs. Limited segmental treatment was successful in three limbs with a midthigh reflux source well below competent terminal and subterminal valves. Six GSV trunks had partial or no occlusion, but only one refluxed. These were anatomical RFO failures (9.5%) but were clinically improved, including the refluxing limb. Neovascularity was not identified in any groin. Thigh varicosities were observed in 12 limbs, including telangiectasias and isolated small tributary branches. New varicosities, linked to refluxing thigh perforators (two), or patent SFJ tributaries (three), were present in five limbs. CONCLUSION: RFO is the ideological opposite of high ligation without GSV stripping. It leaves physiologic tributary flow relatively undisturbed, does not incite groin neovascularity, eliminates the GSV as a refluxing conduit in >90% of limbs and has a 2-year, postadjunctive phlebectomy varicosity prevalence of 7.9%, with symptom score improvement in 95% of limbs with an initial score higher than zero.     

Arteriovenous brain malformations: is functional MR imaging reliable for studying language reorganization in patients? Initial observations

PURPOSE: To determine whether the blood flow abnormalities frequently associated with arteriovenous malformations (AVMs) can alter functional magnetic resonance (MR) imaging evaluation of language lateralization and whether reorganization of language function occurs in patients with brain AVMs. MATERIALS AND METHODS: Eleven patients with left-hemisphere brain AVMs and 10 age-matched control subjects were examined with 1.5-T blood oxygen level-dependent (BOLD) functional MR imaging. Verbal fluency, sentence repetition, and story listening tasks were performed. The functional MR imaging laterality index in the frontal and temporal lobes was defined as the (L - R)/(L + R) ratio, where L and R are the numbers of activated pixels in the left and right hemispheres, respectively. Statistical analyses were performed with Wilcoxon signed rank, Fisher exact, and Kruskal-Wallis tests. RESULTS: Control subjects had left-sided language dominance, although symmetric pixel counts were observed in the frontal lobes in two subjects and in the temporal lobes in one subject. Six patients had left-sided language dominance similar to that observed in control subjects. Five of these patients had AVMs outside frontal or temporal language areas, without flow abnormalities. Five patients had abnormally right-sided asymmetric indexes (below mean control subject value - 2 SDs), which suggested language reorganization (P <.05). Results of Wada examination and/or postembolization functional MR imaging performed in two of these patients showed that the abnormal laterality indexes were at least partly due to severe flow abnormalities that impaired detection of BOLD MR imaging signal intensity. CONCLUSION: These data suggest that flow abnormalities may interfere with language lateralization assessment with functional MR imaging.     

High incidence of myocardial ischemia during postpartum hemorrhage

BACKGROUND: Postpartum hemorrhage remains a major cause of global maternal morbidity and mortality, even in developed countries, despite the use of intensive care units. This study sought to (1) assess whether myocardial ischemia could be associated with and even aggravate hemorrhagic shock in young parturients admitted for postpartum hemorrhage, and (2) identify the independent risk factors for myocardial ischemia. METHODS: On their referral to the intensive care unit, a multidisciplinary team managed parturients with severe postpartum hemorrhage. Ventilation, transfusion, catecholamines, surgery, or angiography with uterine embolization were provided as clinically indicated. Plasma cardiac troponin I levels were used as a surrogate marker of acute myocardial injury and electrocardiograms of myocardial ischemia. RESULTS: A total of 55 parturients were referred with severe postpartum hemorrhage, all in hemorrhagic shock. Twenty-eight parturients (51%) had elevated serum levels of cardiac troponin I (9.4 microg/l [3.7-26.6 microg/l]), which were associated with electrocardiographic signs of ischemia and deteriorated myocardial contractility and correlated with the severity of hemorrhagic shock. Indeed, multivariate analysis identified low systolic and diastolic arterial blood pressure (< 88 and < 50 mmHg, respectively) and increased heart rate (> 115 beats/min) as independent predictors of myocardial injury. In addition, all patients who were given catecholamines also had elevated cardiac troponin I levels. CONCLUSIONS: These results suggest that treatment of postpartum hemorrhage-induced hemorrhagic shock should be coupled with concomitant prevention of myocardial ischemia, even in young parturients.