The Effect of Sex on Heart Rate Variability at High Altitude.

There is evidence suggesting that high altitude (HA) exposure leads to a fall in heart rate variability (HRV) that is linked to the development of acute mountain sickness (AMS). The effects of sex on changes in HRV at HA and its relationship to AMS are unknown. METHODS: HRV (5-min single-lead ECG) was measured in 63 healthy adults (41 men and 22 women) 18-56 yr of age at sea level (SL) and during a HA trek at 3619, 4600, and 5140 m, respectively. The main effects of altitude (SL, 3619 m, 4600 m, and 5140 m) and sex (men vs women) and their potential interaction were assessed using a factorial repeated-measures ANOVA. Logistic regression analyses were performed to assess the ability of HRV to predict AMS. RESULTS: Men and women were of similar age (31.2 ± 9.3 vs 31.7 ± 7.5 yr), ethnicity, and body and mass index. There was main effect for altitude on heart rate, SD of normal-to-normal (NN) intervals (SDNN), root mean square of successive differences (RMSSD), number of pairs of successive NN differing by >50 ms (NN50), NN50/total number of NN, very low-frequency power, low-frequency (LF) power, high-frequency (HF) power, and total power (TP). The most consistent effect on post hoc analysis was reduction in these HRV measures between 3619 and 5140 m at HA. Heart rate was significantly lower and SDNN, RMSSD, LF power, HF power, and TP were higher in men compared with women at HA. There was no interaction between sex and altitude for any of the HRV indices measured. HRV was not predictive of AMS development. CONCLUSIONS: Increasing HA leads to a reduction in HRV. Significant differences between men and women emerge at HA. HRV was not predictive of AMS.

Is asymptomatic bacteriuria a risk factor for prosthetic joint infection?

BACKGROUND: Infection is a major complication after total joint arthroplasty. The urinary tract is a possible source of surgical site contamination, but the role of asymptomatic bacteriuria (ASB) before elective surgery and the subsequent risk of infection is poorly understood. METHODS: Candidates for total hip or total knee arthroplasty were reviewed in a multicenter cohort study. A urine sample was cultured in all patients, and those with ASB were identified. Preoperative antibiotic treatment was decided on an individual basis, and it was not mandatory or randomized. The primary outcome was prosthetic joint infection (PJI) in the first postoperative year. RESULTS: A total of 2497 patients were enrolled. The prevalence of ASB was 12.1% (303 of 2497), 16.3% in women and 5.0% in men (odds ratio, 3.67; 95% confidence interval, 2.65-5.09; P < .001). The overall PJI rate was 1.7%. The infection rate was significantly higher in the ASB group than in the non-ASB group (4.3% vs 1.4%; odds ratio, 3.23; 95% confidence interval, 1.67-6.27; P = .001). In the ASB group, there was no significant difference in PJI rate between treated (3.9%) and untreated (4.7%) patients. The ASB group had a significantly higher proportion of PJI due to gram-negative microorganisms than the non-ASB group, but these did not correlate to isolates from urine cultures. CONCLUSIONS: ASB was an independent risk factor for PJI, particularly that due to gram-negative microorganisms. Preoperative antibiotic treatment did not show any benefit and cannot be recommended.