A Recruitment Maneuver After Apnea Testing Improves Oxygenation and Reduces Atelectasis in Organ Donors After Brain Death.

BACKGROUND: Hypoxemia is the main modifiable factor preventing lungs from being transplanted from organ donors after brain death. One major contributor to impaired oxygenation in patients with brain injury is atelectasis. Apnea testing, an integral component of brain death declaration, promotes atelectasis and can worsen hypoxemia. In this study, we tested whether performing a recruitment maneuver (RM) after apnea testing could mitigate hypoxemia and atelectasis. METHODS: During the study period, an RM (positive end-expiratory pressure of 15 cm H2O for 15 s then 30 cm H2O for 30 s) was performed immediately after apnea testing. We measured partial pressure of oxygen, arterial (PaO2) before and after RM. The primary outcomes were oxygenation (PaO2 to fraction of inspired oxygen [FiO2] ratio) and the severity of radiographic atelectasis (proportion of lung without aeration on computed tomography scans after brain death, quantified using an image analysis algorithm) in those who became organ donors. Outcomes in RM patients were compared with control patients undergoing apnea testing without RM in the previous 2 years. RESULTS: Recruitment maneuver was performed in 54 patients after apnea testing, with a median immediate increase in PaO2 of 63 mm Hg (interquartile range 0-109, p = 0.07). Eighteen RM cases resulted in hypotension, but none were life-threatening. Of this cohort, 37 patients became organ donors, compared with 37 donors who had apnea testing without RM. The PaO2:FiO2 ratio was higher in the RM group (355 ± 129 vs. 288 ± 127, p = 0.03), and fewer had hypoxemia (PaO2:FiO2 ratio < 300 mm Hg, 22% vs. 57%; p = 0.04) at the start of donor management. The RM group showed less radiographic atelectasis (median 6% vs. 13%, p = 0.045). Although there was no difference in lungs transplanted (35% vs. 24%, p = 0.44), both better oxygenation and less atelectasis were associated with a higher likelihood of lungs being transplanted. CONCLUSIONS: Recruitment maneuver after apnea testing reduces hypoxemia and atelectasis in organ donors after brain death. This effect may translate into more lungs being transplanted.

Differential effect of B-vitamin therapy by antiplatelet use on risk of recurrent vascular events after stroke.

BACKGROUND AND PURPOSE: Although several randomized controlled trials failed to show a benefit of B vitamin therapy on composite outcomes of cardiovascular death, myocardial infarction, and stroke among individuals with elevated homocysteine, recent post hoc analyses have suggested that several factors may interact with the effects of vitamin treatment. One post hoc analysis revealed an interaction between B vitamin therapy and antiplatelet use; however, those results have not been replicated in other studies or populations. METHODS: We conducted a post hoc analysis of the Vitamin Intervention for Stroke Prevention (VISP) trial, a randomized controlled trial evaluating treatment with high- versus low-dose B vitamin therapy for secondary prevention of vascular events among stroke survivors with elevated homocysteine. Cox regression models were used to assess primary (recurrent stroke) and secondary (stroke, myocardial infarction, or vascular death) outcomes among individuals on high- versus low-dose vitamin therapy, categorized by antiplatelet use, after adjusting for covariates. RESULTS: Among 3680 participants, 52% took antiplatelet medications. When compared with low-dose therapy, high-dose vitamin therapy was associated with higher stroke risk among individuals on antiplatelets (hazard ratio, 1.43; 95% confidence interval, 1.02-2.01), but trended toward lower risk among those not on antiplatelets (hazard ratio, 0.86; 95% confidence interval, 0.62-1.19). CONCLUSIONS: High-dose B vitamin therapy may be associated with a higher risk of recurrent stroke among stroke survivors taking antiplatelets, but does not have a significant effect on recurrent stroke risk in those who are not on antiplatelets. Future randomized controlled trials may consider evaluating the effect of homocysteine lowering among stroke survivors with elevated homocysteine who are not on antiplatelet therapy.

Homocysteine-lowering therapy and risk of recurrent stroke, myocardial infarction and death: the impact of age in the VISP trial.

BACKGROUND: Clinical trials have failed to show a benefit of B vitamin therapy in reducing composite outcomes of cardiovascular death, myocardial infarction, and stroke among stroke survivors with elevated total serum homocysteine (tHcy) levels. Recent post hoc analyses have shown that numerous factors including age, baseline tHcy levels, folic acid fortification of grains, B12 status, renal function, comorbidities, and medications may modify the effect of B vitamin therapy on vascular risk in individuals with high tHcy. It remains possible that tHcy-lowering therapy may reduce cardiovascular risk in certain subgroups of stroke survivors. Post hoc subgroup analysis of the Heart Outcomes Prevention Evaluation-2 randomized controlled trial, which randomized participants with known cardiovascular disease to tHcy-lowering therapy or placebo, revealed larger treatment benefit for patients aged younger than 69 years; however, that analysis did not control for other factors. The aim of this study was to determine the effect of age on the impact of tHcy-lowering therapy for reducing vascular risk after stroke while controlling for other factors known to modify the effect of tHcy and tHcy-lowering therapy on vascular risk. METHODS: In this post hoc analysis of the Vitamin Intervention for Stroke Prevention (VISP) trial, a randomized controlled trial of tHcy lowering for secondary stroke prevention, we excluded individuals who had poor renal function (glomerular filtration rate <47; the 10th percentile) or were treated with vitamin B12 injections. We assessed the effects of high-dose vitamin replacement on primary (stroke, myocardial infarction, or death) and secondary (stroke) outcomes, after stratifying by age (< vs. ≥ median age, 67 years) and adjusting for demographic and clinical factors. RESULTS: This subgroup consisted of 2,993 individuals. Among individuals older than 67 years, high-dose vitamin therapy was associated with reduced risk of stroke, myocardial infarction or death (adjusted HR 0.76, 95% CI 0.58-0.99) and a trend towards reduced likelihood of stroke (adjusted HR 0.86, 95% CI 0.59-1.25). High-dose vitamin therapy did not impact outcomes among individuals younger than 67 years. CONCLUSIONS: In this post hoc subgroup analysis of the VISP trial, age modified the association between B vitamin therapy and recurrent vascular risk among stroke survivors with elevated serum tHcy levels. Older individuals with stroke were more likely to benefit from B vitamin therapy than younger individuals. These findings can help inform the future design of clinical trials of tHcy-lowering therapy for cardiovascular risk reduction after stroke. © 2014 S. Karger AG, Basel.

Intraventricular Hemorrhage Severity as a Predictor of Outcome in Intracerebral Hemorrhage.

Background/Objective: Intraventricular hemorrhage (IVH) extension after spontaneous supratentorial intracerebral hemorrhage (sICH) is an independent predictor of worse outcome. However, there is a paucity of data looking at the degree of IVH severity and its impact on outcome. This study addresses the contribution of IVH severity to outcome at time of hospital discharge after sICH. Methods: Two hundred and ten patients were included in the study. Baseline demographic and radiologic characteristics were abstracted. First available CT scans were reviewed for hematoma volume and location, IVH extension and presence of hydrocephalus (HCP). IVH severity was calculated using Graeb scale. Multivariate logistic regression models were developed to investigate the association of IVH severity with poor outcomes at hospital discharge, defined as modified Rankin scale score (mRS) >3. Results: Fifty-three percent of patients had IVH extension while 18% had surgical procedures done. Poor outcome (mRS >3) was seen for 56% of patients. Median IVH extension severity on the Graeb scale was two. Presence of IVH was associated with poor outcome in univariate and multivariate analysis (p < 0.005). Compared to patients with no IVH, IVH severity influenced outcome only when Graeb scores were ≥5 (OR = 1.3, 95% CI 0.49-3.23, p = 0.63, and OR = 2.9, 95% CI, 1.1-7.6, p = 0.03 for Graeb <5 and ≥5, respectively. Conclusions: Higher IVH severity (defined as Graeb score ≥5) is associated with worse outcome at time of hospital discharge, while lower IVH severity (Graeb scores 1-4) has similar outcomes to patients without IVH. IVH severity should be used in favor of IVH presence for prognostication purposes.

Invasive and noninvasive multimodal bedside monitoring in subarachnoid hemorrhage: a review of techniques and available data.

Delayed-cerebral ischemia is a major cause of morbidity and mortality in the setting of aneurysmal subarachnoid hemorrhage. Despite extensive research efforts and a breadth of collective clinical experience, accurate diagnosis of vasospasm remains difficult, and effective treatment options are limited. Classically, diagnosis has focused on imaging assessment of the cerebral vasculature. Recently, invasive and noninvasive bedside techniques designed to characterize relevant hemodynamic and metabolic alterations have gained substantial attention. Such modalities include microdialysis, brain tissue oxygenation, jugular bulb oximetry, thermal diffusion cerebral blood flow, and near-infrared spectroscopy. This paper reviews these modalities and examines data pertinent to the diagnosis and management of cerebral vasospasm.