Predicting haemorrhage in pre-hospital traumatic patients: evaluation of the novel heart-to-arm time index.

BACKGROUND: Early recognition of hypovolaemia in trauma patients is very important. However, the most often used clinical signs, such as hypotension and tachycardia, lack specificity and sensitivity. METHODS: We propose a non-invasive index of hypovolaemia, the heart to arm time (iHAT), based on a modified pulse transit time indexed to heart rate. Pulse transit time is the sum of pre-ejection period and vascular transit time. Following pre-load reductions due to hypovolaemia, ventricular diastolic filling time increases causing an increase in pre-ejection-period, pulse transit time, and hence iHAT. One hundred and four consecutive patients with suspected major trauma were enrolled. The primary aim was to evaluate the use of the iHAT for detecting haemorrhage in major trauma. The secondary end point was to compare the specificity and sensitivity of iHAT compared to commonly used indexes. RESULTS: iHAT was calculated in 84 subjects, 11 of whom were haemorrhagic. iHAT discriminated haemorrhagic from non-haemorrhagic group (46.8% vs. 66.9%, P < 0.0001). The cut-off for iHAT with the best compromise between sensitivity (90.9%) and specificity (100%) was reached at the 58.78% level. Comparing haemorrhagic and non-haemorrhagic patients, the area under the ROC curve was 0.952 for iHAT, 0.835 for heart rate, and 0.911 for systolic blood pressure, showing no significant differences. CONCLUSIONS: iHAT is a non-invasive index that can identify haemorrhage in trauma patients with high sensitivity and specificity. These data should be considered as an exploration, but any conclusion should be validated in a new set of consecutive patients.

Effect of fentanyl on heart rate variability during spontaneous and paced breathing in healthy volunteers.

BACKGROUND: Many studies have been conducted to assess the effects of fentanyl on the autonomic nervous system (ANS) by heart rate variability (HRV) analysis, but disagreement on the results is still present due to confounding influences introduced by concomitant administration of other drugs or opioid-related transitory respiratory depression. We performed a single-drug controlled-breathing study on healthy volunteers to assess the impact of fentanyl on ANS. METHODS: HRV as a measure of sympathovagal balance was prospectively analyzed with an autoregressive model in 11 subjects during spontaneous and paced breathing (PB) at 20 breaths/min both before and after fentanyl 1 mcg/kg administration. HRV total power, sympathovagal balance (low-frequency/high-frequency ratio) and normalized spectral powers were considered (LFnu, HFnu). RESULTS: Fentanyl led to a reduction of LFnu (from 55.2+/-23.3 to 43.2+/-24.1, P<0.05) without HFnu increase during PB. A decrease in R-R interval variance (from 3345.6+/-3333.4 to 1806.9+/-1328.6 ms(2), P<0.05) was shown after fentanyl administration during spontaneous but not PB. PB alone decreased the HRV total power and R-R interval variance. CONCLUSIONS: Low-dose fentanyl administration in healthy volunteers leads to sympathetic and overall ANS modulation decrease, with a trend toward vagal activation.