Search

A response by Robert D. Truog to a letter to the editor about his article "Is Informed Consent Always Necessary For Randomized, Controlled Trials?," in the March 11, 1999 issue is presented.

The article focuses on the combination of positive end-expiratory pressure (PEEP) and FIO2 to address the acute respiratory distress syndrome (ARDS). It says that all the issues involved in supporting oxygenation and avoiding harm in clinically user friendly format can be balanced by the strategy. It adds that therapists can follow the PEEP/ FIO2 without individual orders for every change in oxygenation.

An abstract of the article "Left atrial volume measurements before and after left atrial ablation for the treatment of atrial fibrillation," by Jerry D. Walker and colleagues is presented.

Introduction: Left atrial (LA) fibrosis is thought to be a substrate for Atrial Fibrillation (AF) and its ablation emerges as a complementary method for AF management. However, LA fibrosis often continues to increase after ablation and likely affects maintenance of sinus rhythm. Hypothesis: We examined how regression and progression of LA fibrosis affected AF recurrent. Methods: LA enhancement was quantified with Late Gadolinium Enhancement MRI (LGE-MRI) for 127 consecutive AF patients who underwent first time AF ablation. Quantification was done before ablation, 3 months post-ablation and then at least 12 months later. Regressed Fibrosis (RF) was defined as enhancement seen on the first (3-months) post-ablation scan but not on the 1-year post-ablation scan and New Fibrosis (NF) as the enhancement detected only on the 1-year post ablation scan. Results: NF and RF showed no correlation with pre-ablation LA fibrosis. An increase of 1% NF increased the chance of AF recurrence by 3%. (HR 1.03, CI 95% 1 - 1.06, p = 0.05). RF alone showed no impact on future AF recurrence. Hazard ratio for AF recurrence increased when NF become greater (Figure 1-A). Additionally, patients with greater volume of NF (>21%, obtained from ROC analysis) experience significantly more recurrence post-ablation (AF freedom 37% vs 61%, p = 0.01, adjusted for cardiovascular risk factors) than those with less than 21% NF (Figure 1-B). Conclusions: Atrial fibrosis formation is an ongoing process and continues to evolve even after targeted ablation. This data suggests that new fibrosis formation after AF ablation (regardless of pre-ablation enhancement) is a novel marker of long-term procedural outcome and is an independent predictor of AF recurrence. It remains unclear whether contemporary AF management aimed at containing fibrotic structures, can help prolong the arrhythmia free period. [ABSTRACT FROM AUTHOR]

Introduction: Left atrial (LA) volume and function are related to success of atrial fibrillation (AF) ablation. However, the relationship between LA structure and function is not well understood. Magnetic resonance imaging (MRI) is a non-invasive method to assess LA fibrosis and LA function. Hypothesis: Our goal is to evaluate the left atrial functional recovery after successful atrial fibrillation ablation procedure focusing on the ablation lesion sets. Methods: CMR scans were performed in 55 AF patients (66.1±10.5 years) without AF recurrence, at three time points: prior to ablation procedure, in the acute post-ablation period (<48 hours) and at 3 months follow-up. We categorized patients into three groups according to the ablation lesion sets: Gr1{n=11} pulmonary vein isolation only (PVI); Gr2{n=33} PVI, roof line (RL) and posterior wall homogenisation (PH), Gr3{n=11} PVI, RL, PH and additional anterior wall fibrosis homogenization (AH). Maximum (maxLAV), minimum (minLAV) and pre-atrial contraction LA volumes (pre-aLAV) were measured according to the biplane area-length method with CMR. Total, passive and active LA ejection fractions (LAEF) were calculated, and LA fibrosis was quantified using late-gadolinium enhancement images. Results: Comparing the three groups, baseline pre-ablation atrial volumes and function were not significantly different among groups, but Gr3 had higher pre-ablation LA fibrosis% (Gr1 vs Gr2 vs Gr3 11.5±5.1% vs 11.7±4.1% vs 14.8±5.9% p<0.05). In the acute phase, the lowest total LA-EF was identified in Gr3 (Gr1 vs Gr3 total LAEF: 56.9±16.0% vs 37.2±14.9 p<0.05), but during follow-up no significant difference was identified. After 3 months Gr2 showed functional recovery, and total and also active LAEF was significantly higher compared to the baseline function (Gr3 pre-ablation vs follow-up LAEF: 42.5±12.5 vs 51.1±16.5% p<0.005) (Figure). Conclusions: In patient with posterior wall ablation LA function recovered, and additional left atrial fibrosis homogenization did not decrease LA function significantly at follow-up. [ABSTRACT FROM AUTHOR]

Background: Patients with acute carbon monoxide poisoning commonly have cognitive sequelae. We conducted a double-blind, randomized trial to evaluate the effect of hyperbaric-oxygen treatment on such cognitive sequelae. Methods: We randomly assigned patients with symptomatic acute carbon monoxide poisoning in equal proportions to three chamber sessions within a 24-hour period, consisting of either three hyperbaric-oxygen treatments or one normobaric-oxygen treatment plus two sessions of exposure to normobaric room air. Oxygen treatments were administered from a high-flow reservoir through a face mask that prevented rebreathing or by endotracheal tube. Neuropsychological tests were administered immediately after chamber sessions 1 and 3, and 2 weeks, 6 weeks, 6 months, and 12 months after enrollment. The primary outcome was cognitive sequelae six weeks after carbon monoxide poisoning. Results: The trial was stopped after the third of four scheduled interim analyses, at which point there were 76 patients in each group. Cognitive sequelae at six weeks were less frequent in the hyperbaric-oxygen group (19 of 76 [25.0 percent]) than in the normobaric-oxygen group (35 of 76 [46.1 percent], P=0.007), even after adjustment for cerebellar dysfunction and for stratification variables (adjusted odds ratio, 0.45 [95 percent confidence interval, 0.22 to 0.92]; P=0.03). The presence of cerebellar dysfunction before treatment was associated with the occurrence of cognitive sequelae (odds ratio, 5.71 [95 percent confidence interval, 1.69 to 19.31]; P=0.005) and was more frequent in the normobaric-oxygen group (15 percent vs. 4 percent, P=0.03). Cognitive sequelae were less frequent in the hyperbaric-oxygen group at 12 months, according to the intention-to-treat analysis (P=0.04). Conclusions: Three hyperbaric-oxygen treatments within a 24-hour period appeared to reduce the risk of cognitive sequelae 6 weeks and 12 months after acute carbon monoxide poisoning. (N Engl J Med 2002;347:1057-67.) [ABSTRACT FROM AUTHOR]

Provides tips for the prevention of patients with open fractures of long bones. Revelation of bacterial growth in the initial wound cultures; Assertion of the rate of infection; Suggestion of the intake of cephalosporin, the prophylactic antibiotic.

Focuses on the issue of informed consent. The approach in medical interventions of research or therapy; What is allowed in clinical care versus what is allowed in clinical trials; Discussion of research and therapy; Comments about the Nuremberg Code and the Declaration of Helsinki; Proposed criteria for determining whether the requirement of informed consent for a randomized, controlled trial can be waived.