Premium
Comparison of Measures of Compensatory Reserve and Tissue Oxygen in Differentiating Tolerance to Simulated Hemorrhage
Author(s) -
Schlotman Taylor E.,
Howard Jeffrey T.,
Convertino Victor A.
Publication year - 2018
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.2018.32.1_supplement.910.7
Subject(s) - hypovolemia , medicine , presyncope , cardiology , heart rate , forearm , blood pressure , anesthesia , surgery
Background We previously reported that average measurements of compensatory reserve (CRM) and muscle oxygen saturation (SmO 2 ) obtained from a large cohort of humans provided earlier indication of reduced central blood volume than standard vital signs (e.g., blood pressure, heart rate, arterial oxygen saturation). Additionally, CRM was more sensitive and specific in earlier prediction of decompensation than SmO 2 overall. Objective In the present study, we hypothesized that CRM derives its superior predictive qualities from its ability to differentiate between individuals with high (HT) and low (LT) tolerance to central hypovolemia compared with measures of SmO 2 . Methods Continuous noninvasive measures of CRM (calculated from feature changes in the photoplethysmographic arterial waveforms) were collected from 55 healthy volunteer subjects before and during stepwise lower body negative pressure (LBNP) to the point of presyncope. Near infrared spectroscopy was used on the forearm to obtain measures of deep SmO 2 , hydrogen ion concentration ([H + ]), and hemoglobin volume (HbT; decreases reflect vasoconstriction). Using a progressively increasing stepwise protocol, tolerance group was defined by those subjects who did (HT) or did not (LT) complete 60 mmHg LBNP. Data were analyzed using generalized estimating equations (GEE) to account for the repeated measures design. Results Of 55 participants, there were 35 (64%) HT and 20 (36%) LT, 26 (47%) males and 29 females (53%), with a mean age of 28 years (SD=7), height of 172 cm (SD=10) and weight of 72 kg (SD=15). CRM decreased by 97% in a linear fashion across progressive LBNP levels from baseline to −90 mm Hg, while SmO2 decreased by only 39% from baseline to −90 mm Hg. The slope for CRM values across progressive LBNP levels differed significantly between LT and HT individuals (slope difference −0.14; p=0.03). The slope for SmO2 values did not differ between LT and HT individuals across LBNP levels (slope difference=0.06; p=0.18). Conclusion Consistent with our hypothesis, CRM exhibited greater reduction across progressive LBNP levels than SmO 2 . These data support the notions that: 1) CRM can enable more accurate triage of casualties than SmO 2 due to superior ability to differentiate those individuals at highest risk for shock; and 2) continuous monitoring of CRM can allow for earlier detection of continued casualty deterioration. This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal .