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Background: Shock index [SI = the ratio of heart rate (HR) to systolic arterial pressure (SAP)] is a metric used to diagnose patients at risk of impending hemorrhagic shock. W e hypothesized that a metric called the compensatory reserve index (CRI), derived using computer modeling with continuous feature extraction from arterial waveforms, would provide an earlier indicator of cardiovascular instability than SI during progressive central hypovolemia. Methods: There were 15 subjects (men = 8; women = 7) who underwent progressive reduction in central blood volume induced by lower body negative pressure (LBNP) until SAP < 90 mmHg. CRI was normalized on a scale of 1 (normovolemia) to 0 (circulatory volume at which instability occurs) and displayed on a colored bar. The times at which the CRI equaled 0.6 (threshold of green to amber) or 0.3 (threshold of amber to red) were compared to a clinical threshold of SI > 0.9. Results: A SI > 0.9 required 22.4 ± 6.2 min (95%CI = 19 to 25.8 min). CRI reached 0.6 (amber) at 12.5 ± 4.9 min (95%CI = 9.8 to 15.3 min) when SI = 0.61 ± 0.03, and became 0.3 (red) at 20.3 ±5.1 min (95%CI = 17.5 to 23.1 min) when SI = 0.81 ± 1.4. Conclusions: CRI provided a significantly earlier indicator of impending hemodynamic decompensation than SI a 0.9 during progressive LBNP. These results support the notion that the CRI represents an improved 'shock index' as an indicator of impending hemorrhagic shock compared to standard vital signs. [ABSTRACT FROM AUTHOR]

Introduction: In the setting of remote military triage, when physical access to the patient is not possible, traditional physiological measurements available to a combat medic may not differentiate between a wounded soldier and an active soldier. We tested the hypothesis that changes in high-frequency R-R interval spectral power (RRI HF) and pulse pressure (PP) would differ between progressive central hypovolemia (simulated hemorrhage) and exercise to evaluate their potential for remotely distinguishing active from bleeding soldiers. The RRI HF and PP were used because of their ability to track central hypovolemia. Methods: There were 12 (8 female/4 male) healthy, normotensive, non- smoking subjects (age 27 ± 2 yr; height 169 ± 3 cm; weight 68 ± 5 kg) who were exposed to progressive lower body negative pressure (LBNP) and a supine cycle ergometer protocol. ECG and blood pressure were measured continuously. Exercise workloads were determined by matching the heart rate (HR) responses to each LBNP level. Data were analyzed in time and frequency domains. Results: HR increased from 67 ± 3 bpm at rest to 101 ± 4 bpm by -60 mmHg LBNP and was matched within 5% during exercise. By the final stage, RRI HF decreased by a similar magnitude during both LBNP (-78 ± 7%) and exercise (-85 ± 6%). PP decreased by 30 ± 4% with LBNP compared with an increase of 20 ± 6% during exercise. Conclusion: Monitoring PP in combination with RRI HF would distinguish a bleeding from an active soldier. Technologies that incorporate telemetry to track these derived vital signs would provide a combat medic with remote decision support to assess soldier status on the battlefield. [ABSTRACT FROM AUTHOR]

Examines the use of angiotensin receptor blocker treatment for systolic hypertension by researchers Athens, Greece. Identification of systolic blood pressure as a major cardiovascular risk factor associated with arterial stiffness; Evidence showing the markers of arterial stiffness to be independent predictors cardiovascular risk; Implication of the renin-angiotensin system in the pathogenesis of systolic hypertension and arterial stiffness; Safety and efficacy of angiotensin receptor blocker-based treatment strategy.