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Purpose: The aim of this study is to study the feasibility, safety, and physiological effects of pulse pressure variation (PPV)-guided fluid therapy in patients after cardiac surgery., Materials and Methods: We conducted a pilot prospective before-and-after study during mandatory ventilation after cardiac surgery in a tertiary intensive care unit. We introduced a protocol to deliver a fluid bolus for a PPV≥13% for at least >10 minutes during the intervention period., Results: We studied 45 control patients and 53 intervention patients. During the intervention period, clinicians administered a fluid bolus on 79% of the defined PPV trigger episodes. Median total fluid intake was similar between 2 groups during mandatory ventilation (1297 mL [interquartile range 549-1968] vs 1481 mL [807-2563]; P=.17) and the first 24 hours (3046 mL [interquartile range 2317-3982] vs 3017 mL [2192-4028]; P=.73). After adjusting for several baseline factors, PPV-guided fluid management significantly increased fluid intake during mandatory ventilation (P=.004) but not during the first 24 hours (P=.47). Pulse pressure variation-guided fluid therapy, however, did not significantly affect hemodynamic, renal, and metabolic variables. No serious adverse events were noted., Conclusions: Pulse pressure variation-guided fluid management was feasible and safe during mandatory ventilation after cardiac surgery. However, its advantages may be clinically small., (Copyright © 2014 Elsevier Inc. All rights reserved.)

Background: Near-infrared spectroscopy of the thenar eminence (NIRSth) can be used at the bedside to assess tissue oxygenation (StO2), the reperfusion response to ischaemia and the tissue haemoglobin index (THI). Its ability to estimate forearm blood flow (FBF) has not previously been assessed., Objectives: We aimed to test whether short-lived venous occlusion-induced changes in NIRSth-derived THI (ΔTHI/ minute) correlate with strain gauge plethysmography (SGP) measurements., Methods: We measured FBF in nine volunteers with SGP by venous occlusion, while estimating ΔTHI. Measurements were obtained in two forearm positions (elevated and horizontal) at baseline and during induced hyperaemia., Results: We performed 246 paired measurements at rest and after occlusion-induced hyperaemia. At rest, mean SGP-estimated FBF was 3.5-3.6 mL/dL/minute at baseline, compared with 12.9-13.6 mL/dL/minute during hyperaemia. At rest, ΔTHI was 6.1-8.2/minute, compared with 29.7-32.5/minute during hyperaemia. ΔTHI was a significant predictor of SGP FBF (P < 0.01), with stronger correlation during hyperaemia (P < 0.01). An equation was developed to convert ΔTHI/minute into FBF at mL/dL/minute (FBF = 0.362 ΔTHI/minute + 0.864)., Conclusions: NIRSth can be used to estimate FBF. Given its portability and its ability to also measure StO2 and vascular reactivity, NIRSth can assist in providing a comprehensive bedside assessment of the forearm circulation in critically ill patients.

Background: Near-infrared spectroscopy of the thenar eminence (NIRSth) is a non-invasive bedside method for assessing tissue oxygenation. The vascular occlusion test (VOT) with a pressure cuff can be used to provide a dynamic assessment of the tissue oxygenation response to ischaemia. VOT has been applied to assess the microcirculation by NIRSth in critically ill patients. The optimal mode of performing such VOT, however, remains controversial., Design, Participants and Setting: Prospective observational study among a cohort of 11 healthy volunteers in a tertiary intensive care department., Intervention: Measurement of NIRS-derived parameters using 1-, 2- and 3-minute VOTs or VOT to 40% tissue oxygen saturation (StO(2))., Main Outcome Measure: Changes in StO(2) and tissue haemoglobin index (THI) over time, and relative change from baseline for StO(2) and THI., Results: Mean baseline StO(2) was 80% (SD, 5%) and mean THI was 13.7 (SD, 1.9). The lowest StO(2) at the end of the VOT was 39% (SD, 13%) and 39% (SD, 2%) in the 3- minute and the 40% StO(2) VOTs, respectively. The duration of the 40% StO(2) VOT ranged from 1:35 to 8:21 minutes (median, 3:29 min). There was a difference between the StO(2) curves for the 3-minute and 40% StO(2) VOT (P = 0.005) but not the THI curves. Reported pain score was a median of 3.5 (IQR, 2.5-5.5) and 4 (IQR 2-4) for the 3-minute and 40% StO(2) VOTs, respectively., Conclusions: The 3-minute VOT and the 40% StO(2) appear equivalent. However, the 3-minute VOT carries a degree of decreased patient discomfort and shorter overall duration of execution.