Predicted body weight relationships for protective ventilation - unisex proposals from pre-term through to adult.

BACKGROUND: The lung-protective ventilation bundle has been shown to reduce mortality in adult acute respiratory distress syndrome (ARDS). This concept has expanded to other areas of acute adult ventilation and is recommended for pediatric ventilation. A component of lung-protective ventilation relies on a prediction of lean body weight from height. The predicted body weight (PBW) relationship employed in the ARDS Network trial is considered valid only for adults, with a dedicated formula required for each sex. No agreed PBW formula applies to smaller body sizes. This analysis investigated whether it might be practical to derive a unisex PBW formula spanning all body sizes, while retaining relevance to established adult protective ventilation practice. METHODS: Historic population-based growth charts were adopted as a reference for lean body weight, from pre-term infant through to adult median weight. The traditional ARDSNet PBW formulae acted as the reference for prevailing protective ventilation practice. Error limits for derived PBW models were relative to these references. RESULTS: The ARDSNet PBW formulae typically predict weights heavier than the population median, therefore no single relationship could satisfy both references. Four alternate piecewise-linear lean body-weight predictive formulae were presented for consideration, each with different balance between the objectives. CONCLUSIONS: The 'PBWuf + MBW' model is proposed as an appropriate compromise between prevailing practice and simplification, while also better representing lean adult body-weight. This model applies the ARDSNet 'female' formula to both adult sexes, while providing a tight fit to median body weight at smaller statures down to pre-term. The 'PBWmf + MBW' model retains consistency with current practice over the adult range, while adding prediction for small statures.

The Effect of Treatment of Obstructive Sleep Apnea on Glycemic Control in Type 2 Diabetes.

RATIONALE: There is uncertainty about the effects of treating obstructive sleep apnea on glycemic control in patients with type 2 diabetes. OBJECTIVES: To determine whether treatment of obstructive sleep apnea in patients with type 2 diabetes improves glycemic control. METHODS: In this trial, we randomized patients with type 2 diabetes and no previous diagnosis of obstructive sleep apnea, with a glycated hemoglobin level of 6.5-8.5%, and an oxygen desaturation index of 15 or more events per hour to positive airway pressure therapy or to usual care. MEASUREMENTS AND MAIN RESULTS: A total of 416 patients met the entry criteria as determined by each site and were randomized. Of the 298 participants who met centrally adjudicated entry criteria, no differences between the study groups were seen for change in glycated hemoglobin. Furthermore, there were no between-group differences when analyses were restricted to those with poorer baseline glycemic control, those with more severe sleep apnea, or those who were adherent to therapy. A greater fall in diastolic blood pressure occurred in the positive airway pressure group than in the usual care group (-3.5 mm Hg vs. -1.5 mm Hg; P = 0.07). This difference was significant in those who were adherent to positive airway pressure therapy (-4.4 mm Hg vs. -1.6 mm Hg; P = 0.02). There was a significant reduction in sleepiness in the positive airway pressure therapy group (P < 0.0001). Quality of life assessment revealed improvements in vitality, mental health, and mental component summary scores in the positive airway pressure therapy group. CONCLUSIONS: This trial showed no effect of positive airway pressure therapy on glycemic control in patients with relatively well-controlled type 2 diabetes and obstructive sleep apnea. Clinical trial registered with www.clinicaltrials.gov (NCT00509223).

Assessment of the impact on compliance of a new CPAP system in obstructive sleep apnea.

BACKGROUND: Despite the efficacy of continuous positive airway pressure (CPAP) for the treatment of obstructive sleep apnea (OSA), compliance with therapy remains suboptimal.The aim of this study was to determine whether the use of S9TM increased compliance in established CPAP users. METHODS: Subjects with OSA (50) were recruited into the study. When subjects entered the study, 28 days of respective compliance data were downloaded from the patient's usual CPAP device. Subjects trialled the S9 CPAP for 28 days.Subjects then resumed use of their usual CPAP for 28 days.Compliance data from the patient's usual CPAP pre- and post-trialling S9 were compared with data from the S9 CPAP. RESULTS: Patients were significantly more compliant when using the S9 than their usual CPAP device both pre- and post-S9 based on average daily usage. CPAP pre-S906.58±1.95(mean hours±SD), S907.08±1.18 h and CPAP post-S906.71±1.72 h. The difference between CPAP pre-S9 and S9 was 0.5 h (p00.003). The difference between S9 and CPAP post-S9 was 0.35 h (p00.01). There was no significant difference between CPAP pre-S9 and CPAP post-S9 (p00.34).Patients also completed questionnaires comparing the S9 system to their usual device. Subjective feedback showed a strong preference for the S9. CONCLUSIONS: Participants were significantly more compliant when using the S9 than their usual CPAP device both pre and post-S9 use