Impact of sex on use of low tidal volume ventilation in invasively ventilated ICU patients—A mediation analysis using two observational cohorts

Background Studies in patients receiving invasive ventilation show important differences in use of low tidal volume (VT) ventilation (LTVV) between females and males. The aims of this study were to describe temporal changes in VT and to determine what factors drive the sex difference in use of LTVV. Methods and findings This is a posthoc analysis of 2 large longitudinal projects in 59 ICUs in the United States, the ‘Medical information Mart for Intensive Care III’ (MIMIC III) and the ‘eICU Collaborative Research DataBase’. The proportion of patients under LTVV (median VT < 8 ml/kg PBW), was the primary outcome. Mediation analysis, a method to dissect total effect into direct and indirect effects, was used to understand which factors drive the sex difference. We included 3614 (44%) females and 4593 (56%) males. Median VT declined over the years, but with a persistent difference between females (from median 10.2 (9.1 to 11.4) to 8.2 (7.5 to 9.1) ml/kg PBW) vs. males (from median 9.2 [IQR 8.2 to 10.1] to 7.3 [IQR 6.6 to 8.0] ml/kg PBW) (P < .001). In females versus males, use of LTVV increased from 5 to 50% versus from 12 to 78% (difference, –27% [–29% to –25%]; P < .001). The sex difference was mainly driven by patients’ body height and actual body weight (adjusted average causal mediation effect, –30% [–33% to –27%]; P < .001, and 4 [3% to 4%]; P < .001). Conclusions While LTVV is increasingly used in females and males, females continue to receive LTVV less often than males. The sex difference is mainly driven by patients’ body height and actual body weight, and not necessarily by sex. Use of LTVV in females could improve by paying more attention to a correct calculation of VT, i.e., using the correct body height.

Ideal Body Weight-Based Dosing of Rabbit Antithymocyte Globulin for Cost Minimization in Kidney Transplantation

Introduction: Contemporary dosing strategies for rabbit anti-thymocyte globulin (rATG) in kidney transplantation aim to reduce cumulative exposure, minimizing long-term adverse events. The use of ideal body weight-based dosing has been trialed, however concern for increased rejection post-transplant exists due to lower doses of rATG. Research Questions: The primary aim of this study was to compare rejection rates between rATG dosing protocols using actual body weight and ideal body weight and secondarily to evaluate cost savings following protocol implementation. Design: This was a retrospective study surrounding implementation of an ideal body weight-based dosing protocol for rATG. We compared 75 kidney transplant recipients in whom rATG was dosed based on actual body weight (pre-protocol group) to 64 in whom dosing was based on ideal body weight (post-protocol group), following a nine-month washout. Results: The mean cumulative rATG dose in the pre-protocol group was 6.3 mg/kg of actual body weight. When ideal body weight was used in the post-protocol group, the mean dose was 4.5 mg/kg of actual body weight. The rejection rate was 18.7% pre-protocol and 23.4% postprotocol, which did not represent a statistically significant difference (p = 0.491). The actual annual cost savings after protocol implementation exceeded $162,000, approximately $2,500 per patient. Conclusion: Results suggest ideal body weight-based dosing of rATG may reduce exposure and cost, without significantly impacting the risk of rejection in kidney transplant recipients. More studies are needed to confirm these findings.

What is the Best Predictor of Phenobarbital Pharmacokinetics to Use for Initial Dosing in Neonates?

Phenobarbital is a first-line treatment of various seizure types in newborns. Dosage individualization maximizing the proportion of patients with drug levels in therapeutic range or sufficient treatment response is still challenging. The aim of this review was to summarize the available evidence on phenobarbital pharmacokinetics in neonates and to identify its possible covariates suitable for individualization of initial drug dosing. Several covariates have been considered: body weight and height, body surface area, gestational and postnatal age, laboratory parameters of renal and hepatic functions, asphyxia, therapeutic hypothermia, extracorporeal membrane oxygenation (ECMO), drug interactions, and genetic polymorphisms. The most frequently studied and well-founded covariate for the estimation of phenobarbital dosing is actual body weight. Loading dose of 15–20 mg/kg followed by a maintenance dose of 3–5 mg/kg/day seems to be accurate. However, the evidence for the other covariates with respect to dosing individualization is not sufficient. Doses at the lower limit of suggested range should be preferred in patients with severe asphyxia, while the upper limit of the range should be targeted in neonates receiving ECMO support.

Self-perception of Body Weight and Physical Activity with its Relationship to Actual Body Weight among Students in a Medical College: An Analytical Cross-sectional Study

Introduction: Obesity and sedentary life style are becoming more prevalent among the student generation. Every human being has a very good insight about the outlook. But many are not able to maintain what they perceive. During this survey, the students get a vivid picture of their real body weight and their perception of their body structure. Aim: To compare the self-perceived body weight with actual body weight among medical students and to analyse the perceptions and practice of medical student’s related to physical activity. Materials and Methods: This analytical cross-sectional study included 400 medical students. Self-perceived body image was assessed using Silhouette matching technique. Students represented the figure how they currently look (Feel) and how they actually wanted to look (Ideal). The Feel minus Ideal Discrepancy (FID) score was noted. Actual body weight and height were measured. Body Mass Index (BMI) was calculated using the Quetelet formula- weight(Kg)/height(metres)2. Perceptions and practice of physical activity were assessed using Exercise Benefits/Barrier Scale (EBBS). Comparison of perceived and actual body weight was done by Student’s Independent t-test and Pearson correlation test using Statistical Package for the Social Sciences (SPSS) version 17.0. Results: The actual BMI and perceived BMI showed strong positive correlation (r= 0.726; p=0.0001). Males had high exercise benefit scores (92) when compared with females (86) (p=0.0002). The students had high total score (benefit score plus barrier score); males had 127 and females had 124 (p=0.003) and high benefit/barrier ratio. Conclusion: Actual BMI and self-perceived BMI were well correlated indicating participant’s awareness of their body image. Male participants were more actively involved in physical activity and more concerned about maintaining their body weight. All students had higher benefit scores which is a favourable sign towards a healthy and active physical life.

Urine Output Calculated Using Actual Body Weight may Result in Overestimation of Acute Kidney Injury for Obese Patients

Background: The derived hourly urine output (UO) indexed by body weight is one of the major criteria for diagnosis of acute kidney injury (AKI). However, it is unknown whether actual body weight (ABW) or ideal body weight (IBW) should be used. This study aims to explore whether UO calculation based on ABW might lead to overestimation of AKI.Methods: AKI patients identified in the MIMIC database by different components of the KDIGO guidelines and different definitions of body weight were retrospectively studied. We compared hospital and 90-day mortality to decide whether AKI patients diagnosed by ABW- or IBW-normalized UO had the same outcome.Results: In the cohort of 14,725 patients, AKI was identified in 4,298 (29.19%) and 3,060 (20.78%) patients respectively when ABW or IBW was used to calculate hourly UO (p < 0.001). AKI stages differed between these patients (p < 0.001) with a kappa of 0.87 (95% CI, 0.86 ~ 0.88) and an agreement percentage of 90.40%. Multivariate logistic regression revealed AKI patients identified by UO calculated from ABW had similar hospital and 90-day mortality to that of patients with no evidence of AKI. Whereas AKI patients identified by SCr or by both ABW and IBW had over twice higher the risks of hospital death, 1.7 and 1.4 times higher the risks of 90-day death respectively compared with patients with no evidence of AKI. Results were confirmed in sensitivity analysis where patients whose admission creatinine levels were within the normal reference ranges and sepsis patients were studied.Conclusions: Calculating hourly body weight normalized UO using ABW may lead to underestimation of UO and overestimation of AKI.