Sex-Based Differences in Depth of Soft Tissue and Bone Diameter at the Sternal Intraosseous Catheter Insertion Site

Background Intraosseous (IO) catheters are commonly used to rapidly obtain vascular access for critically-ill patients in the emergency department (ED). While the sternum is a common IO insertion site for adult subjects, little is known about sex-based variation in the proper depth of insertion. Methods A retrospective cohort study was performed, utilizing CT scans obtained from DMC over a ten-year period (2009-2018) to estimate soft tissue depth overlying the recommended sternal IO insertion site. Depths of soft tissue from skin surface to bone surface (Measurement A) and from skin surface to the opposite bony cortex (Measurement B) were measured using standard radiologic software. Results Our data includes 32 male and 21 female subjects with a body mass index (BMI) between 18.5 and 25. Measurement A for males (x̄=17.89 mm, σ=8.91) was significantly larger than for females (x̄=12.98 mm, σ=5.96) (p=0.0308). Sternal diameter (Measurement B-Measurement A) was also significantly larger in males (x̄=17.15 mm, σ=5.06) compared to females (x̄=13.75 mm, σ=4.20) (p=0.0138). Measurement A was ≤25-mm in 78% of males and 90% of females. Conclusions Our results suggest that sex-based differences exist in soft tissue depth and bone diameter at the sternal site, despite similar BMI values. Since common IO needle lengths are 25-mm and 45-mm, these results suggest that 25-mm needles are sufficient for most patients in this BMI category; however, 22% of males and 10% of females studied would have required the longer 45-mm needle. Future studies with larger cohorts are needed to further validate these findings

Biological sex is a predictor of pretibial subcutaneous tissue depth for intraosseous catheter insertion

Introduction Intraosseous (IO) vascular access is most commonly used when critical patients need rapid establishment of vascular access. They have shown high rates of successful placement, with the proximal tibia showing the highest first-attempt success rates. Proper establishment of vascular access requires a needle properly sized to enter the bony cortex and stay there. In this study, we analyzed demographic associations with pre-tibial subcutaneous tissue depth (PTSTD). Methods The PTSTD was calculated using computed tomography (CT) images of adult (³ 18 years old) patients. Variables including side, age, sex, height, weight, BMI, hypertension, diabetes mellitus, atherosclerosis, coronary artery disease, and osteoarthritis were analyzed statistically. Results 368 patients were included in the final data analysis. Patient body mass index, height and weight showed a statistically significant impact on PTSTD overall, and betweenx \u3e 20 mm and \u3c 20 mm and \u3e 40 mm groups. Only height displayed a statistically significant effect between 40 mm \u3e x \u3e 20 mm and \u3e 40 mm group. Sex displayed a statistically significant effect on PTSTD. Conclusions Female sex and higher BMI appear to be related to increased soft tissue thickness in this patient population. Longer catheters may be needed for some obese patients, especially females

Sex-Based Differences in Depth of Soft Tissue at the Proximal Tibia Intraosseous Catheter Insertion Site

Background Intraosseous (IO) catheters are commonly used to rapidly obtain vascular access for critically-ill patients in the emergency department (ED). Although the proximal tibia (PT) is a standard IO insertion site for adult subjects, little is known about sex-based variation in the proper depth of insertion. Methods A retrospective cohort study was performed, utilizing CT scans obtained from DMC over a ten-year period (2009-2018) to estimate soft tissue depth overlying the recommended PT-IO insertion site. Depths of soft tissue from skin surface to bone surface (Measurement A) and from skin surface to the opposite bony cortex (Measurement B) were measured using standard radiologic software. Results A total of 217 subjects were enrolled, including 106 (48.9%) males. Body mass index (BMI) was not significantly different between sexes (p=0.188). Measurement A for females (x̄=21.65 mm, σ=8.17) was significantly greater than for males (x̄=13.64 mm, σ=5.52) (p\u3c0.0001). Measurement A was \u3e25-mm in 5.7% of males and 27.0% of females (p\u3c0.001). Measurement B was \u3c45-mm in 24.5% of males and 21.6% of females. Conclusion Our results suggest that sex-based differences exist in soft tissue depth at the PT site, despite similar BMI values. Since common IO needle lengths are 25-mm and 45-mm, these results have profound implications. The 25-mm needle would have been too short for more than one-fourth of female subjects. However, a 45-mm catheter would have been too long for almost one-fourth of all subjects. Further study is needed to determine whether this sex difference exists in a larger cohort of patients

The impact of alternative trait-scaling hypotheses for the maximum photosynthetic carboxylation rate (Vcmax) on global gross primary production

The maximum photosynthetic carboxylation rate (Vcmax) is an influential plant trait that has multiple scaling hypotheses, which is a source of uncertainty in predictive understanding of global gross primary production (GPP). Four trait-scaling hypotheses (plant functional type, nutrient limitation, environmental filtering, and plant plasticity) with nine specific implementations were used to predict global Vcmax distributions and their impact on global GPP in the Sheffield Dynamic Global Vegetation Model (SDGVM). Global GPP varied from 108.1 to 128.2 PgC yr−1, 65% of the range of a recent model intercomparison of global GPP. The variation in GPP propagated through to a 27% coefficient of variation in net biome productivity (NBP). All hypotheses produced global GPP that was highly correlated (r = 0.85–0.91) with three proxies of global GPP. Plant functional type-based nutrient limitation, underpinned by a core SDGVM hypothesis that plant nitrogen (N) status is inversely related to increasing costs of N acquisition with increasing soil carbon, adequately reproduced global GPP distributions. Further improvement could be achieved with accurate representation of water sensitivity and agriculture in SDGVM. Mismatch between environmental filtering (the most data-driven hypothesis) and GPP suggested that greater effort is needed understand Vcmax variation in the field, particularly in northern latitudes