Ultrasound in forearm fractures: a pragmatic study assessing the utility of Point of Care Ultrasound (PoCUS) in identifying and managing distal radius fractures.

BACKGROUND: Point of Care Ultrasound (PoCUS) is a safe, non-invasive tool for identifying distal radius fractures and can potentially be utilised to assist clinicians to reduce displaced fractures. We aim to test whether PoCUS is accurate to identify distal radius fractures and to determine how PoCUS performs as a tool to confirm a successful fracture reduction. METHODS: A pragmatic prospective observational study was done in adult patients presenting with forearm injuries resulting in Colle's type distal radius fractures. Adults who presented to the emergency department (ED) with a suspected distal forearm fracture from August 2018 to July 2019 were conveniently sampled for inclusion into the study when a trained ED ultra-sonographer was available. PoCUS scans over the point of maximal tenderness were done using a high frequency linear transducer (7.5-10 mHz) prior to X-ray. Patients who required a manipulation of the fracture had a second ultrasound scan immediately after the procedure before the second X-ray was ordered. PoCUS scans were compared to X-rays for accuracy in both groups. RESULTS: Fractures were identified in 44 out of 47 included patients using both PoCUS and X-ray modalities. This showed a sensitivity of 100% (95% CI: 90-100%) and specificity of 100% (95% CI: 31-100%). Fracture manipulation was required in 35 out of 44 patients. The sensitivity and specificity of PoCUS in determining alignment accuracy when compared to X-ray were 100% (95% CI: 83-100%) and 64% (95% CI: 32-88%) respectively. The PPV and NPV were 86% (95% CI: 66-95%) and 100% (95% CI: 56-100%) respectively. Ten out of 44 (23%) patients with distal radius fractures ultimately required an Open Reduction and Internal Fixation (ORIF). CONCLUSION: Our study supports the use of PoCUS for identifying distal radius forearm fractures and may have some value in assisting clinicians to determine post reduction success. We still advocate using standard X-ray radiographs to confirm successful or adequate cortical alignment following a manipulation.

Physiological range of peak cardiac power output in healthy adults.

AIMS: The purpose of this study was to indicate the normal range for peak cardiac power output (CPO(peak)) in healthy adults and to explore age- and sex-related variations of this parameter. METHODS AND RESULTS: Using the non-invasive exponential CO(2) rebreathing technique [J.G. Defares, J Appl Physiol13 (1958) 159], cardiac output was measured at an exercise intensity determined to coincide with > or =95% of peak oxygen consumption in 102 healthy adults (mean +/- SD, age 43 +/- 13 years, body mass 74 +/- 13 kg). Peak cardiac power was then computed from measurements of peak cardiac output (Q(Tpeak)) and peak mean arterial pressure (MAP(peak)) using the equation described by Cooke et al. [Heart79 (1998) 289]. Peak oxygen consumption in the study population was 2.42 (+/-0.74) l min(-1) and subjects achieved 101 +/- 7% of this value during the measurement of . was 17.3 (+/-4) l min(-1), and CPO(peak) was computed as 4.5 (+/-1.2) W. CPO(peak) ranged from 3.11 to 7.94 W in men and 2.53 to 5.57 W in women. Additionally, ageing appears to be associated with a significant loss of peak cardiac power in men that is not apparent in women. CONCLUSION: Although the sample size remains moderate, the CPO values attained were normally distributed and these values provide a useful indication of the normal range for CPO(peak) in healthy adults.

The reliability of short-term measurements of heart rate variability.

Short-term assessment of heart rate variability (HRV) is a non-invasive technique to examine ANS function. Within the literature, HRV is commonly referred to as a reliable measurement technique. The aim of this review was to assess the accuracy of this description based upon a comprehensive review of the available data concerning reliability of short-term HRV measures. Reviewing only studies using appropriate statistical analyses, it was determined that reliability coefficients for HRV measures were highly varied. Coefficients of variation ranged from <1% to >100%. Similar variation was found in studies using the intraclass correlation coefficient values, and limits of agreement. Reliability coefficients reported displayed some distinct patterns. Firstly, where measurements were made during interventions such as tilt or pharmacological stimulation, reliability was poorer than when HRV was measured at rest. Secondly, clinical populations displayed poorer reliability than healthy subjects. There was little effect of test-retest duration on reliability and although no single HRV measurement appeared less reliable than another, there was evidence that optimal data collection conditions for specific frequency domain measures exist. Describing HRV as a reliable measurement technique appears to be a gross oversimplification, as results of reliability studies are heterogeneous, and dependent on a number of factors. Further studies are required, particularly in clinical populations to assess HRV reliability. Authors should refer to coefficients from similar populations measured under similar conditions when making future sample size calculations.

Effects of exercise on heart rate variability: inferences from meta-analysis.

INTRODUCTION: Chronic exercise training produces a resting bradycardia that is thought to be due partly to enhanced vagal modulation. PURPOSE: The aim of the present study was to determine the effects of exercise training on heart rate and measures of heart rate variability associated with vagal cardiac modulation and to quantify the relationship between changes in these measures. METHODS: A random effects model of effect size (d) for change in high frequency (HF) power and RR interval was calculated. Within-group heterogeneity was assessed using the Q statistic. Where heterogenous effects were found, subgroup analyses were performed using the between-group Q statistic. RESULTS: A meta-analysis of 13 studies measuring HF (N=322 cases) produced an overall effect size of d=0.48 (C.I. 0.26-0.70, P=0.00003). Twelve studies (298 cases) reported a change in RR interval with an overall effect size of d=0.75 (C.I. 0.51-0.96, P<0.00001). Effect sizes for RR interval data were significantly heterogenous. Subgroup analysis revealed significantly smaller responses of RR interval to training in older subjects (P<0.1). Effect sizes for change in HF were homogenous, although a trend toward an attenuated response to training was exhibited in older subjects (P>0.10). Linear, quadratic, and cubic fits all revealed weak (P>0.05) relationships between effect sizes for change in HF and RR interval. DISCUSSION: Exercise training results in significant increases in RR interval and HF power. These changes are influenced by study population age. The smaller effect size for HF and weak relationship between HF and RR interval suggest factors additional to increased vagal modulation are responsible for training bradycardia.