Feasibility and pilot study of passive heat therapy on cardiovascular performance and laboratory values in older adults.

BACKGROUND: Chronic heat therapy may have beneficial effects on cardiovascular function. These effects may be more pronounced in older adults. We performed a pilot feasibility study of repeated heat therapy sessions in a hot tub (40.5 °C) in older adults while wearing a noninvasive hemodynamic monitor. As part of the protocol, the volunteers underwent cardiovascular performance testing pre- and post-intervention. METHODS: Fifteen volunteers > 50 years old underwent 8-10 separate 45-min hot tub session over 14 days in this exploratory and mixed methods trial. The participants had maximal oxygen consumption (VO2 max) and other cardiovascular data measured via exercise treadmill testing prior to and after all hot tub sessions. The participants also wore noninvasive fingertip volume clamp monitors while immerged in hot water that calculated systemic vascular resistance, heart rate, blood pressure, and cardiac output in order to ascertain the feasibility and utility of this data. Other laboratory studies were obtained pre- and post-intervention. The protocol was determined feasible if the heat therapy and cardiovascular testing was completed by at least 90% (14/15 subjects). Feasibility of the noninvasive monitor was determined by the fidelity of the results. Secondary exploratory outcomes were analyzed for differences to identify if they are acceptable to include in an efficacy trial. RESULTS: All participants completed the study protocol identifying the feasibility of the protocol. The noninvasive hemodynamic monitors successfully recorded cardiac output, systemic vascular resistance, heart rate, and blood pressure with fidelity based on the analysis of recordings. In the secondary analyses, we found no difference in the pre- to post-intervention measurement of VO2 max but did find increased exercise duration following hot tub therapy compared with prior to the therapy (571 s versus 551 s). CONCLUSIONS: The current pilot study protocol is feasible for the purpose of analyzing the effects of heat therapy and cardiovascular performance in older adults while wearing a noninvasive hemodynamic monitor and undergoing treadmill stress testing. Secondary analyses found increased exercise tolerance but no differences in VO2 max following heat sessions.

Comparing the associations of central venous pressure and pulmonary artery pulsatility index with postoperative renal injury.

Objective: Cardiac surgery-associated acute kidney injury (CS-AKI) is associated with significant morbidity and mortality. We investigated the association of postoperative central venous pressure (CVP) and pulmonary artery pulsatility index (PAPi) with the development of CS-AKI. Methods: This was a single-center, retrospective cohort study of patients undergoing cardiac surgery. CVP and PAPi were acquired hourly postoperatively and averaged for up to 48 h. PAPi was calculated as [(Pulmonary Artery Systolic Pressure-Pulmonary Artery Diastolic Pressure) / CVP]. The primary aim was CS-AKI. Secondary aims were need for renal replacement therapy (RRT), hospital and 30-day mortality, total ventilator and intensive care unit hours, and hospital length of stay. Logistic regression was used to calculate odds of development of renal injury and need for RRT. Results: One thousand two hundred eighty-eight patients were included. The average postoperative CVP was 10.3 mmHg and average postoperative PAPi was 2.01. Patients who developed CS-AKI (n = 384) had lower PAPi (1.79 vs. 2.11, p < 0.01) and higher CVP (11.5 vs. 9.7 mmHg, p < 0.01) than those who did not. Lower PAPi and higher CVP were also associated with each secondary aim. A standardized unit decrease in PAPi was associated with increased odds of CS-AKI (OR 1.39, p < 0.01) while each unit increase in CVP was associated with both increased odds of CS-AKI (OR 1.56, p < 0.01) and postoperative RRT (OR 1.49, p = 0.02). Conclusions: Both lower PAPi and higher CVP values postoperatively were associated with the development of CS-AKI but only higher CVP was associated with postoperative RRT use. When differences in values are standardized, CVP may be more associated with development of CS-AKI when compared to PAPi.

Impact of Early, Low-Dose Factor VIIa on Subsequent Transfusions and Length of Stay in Cardiac Surgery.

OBJECTIVE: Recombinant factor VII (rFVIIa) is used to treat cardiac surgical bleeding in an off-label manner. However, optimal dosing and timing of administration to provide efficacious yet safe outcomes remain unknown. DESIGN: Retrospective, observational study. SETTING: Tertiary care academic center. PARTICIPANTS: Cardiac surgical patients (N = 214) who received low-dose rFVIIa for cardiac surgical bleeding. INTERVENTIONS: Patients were allocated into one of three groups based on timing of rFVIIa administration during the course of bleeding resuscitation based on the number of hemostatic products given before rFVIIa administration: group one = ≤one products (n = 82); group two = two-to-four products (n = 73); and group three= ≥five products (n = 59). MEASUREMENTS AND MAIN RESULTS: Patients who received low-dose rFVIIa later in the course of bleeding resuscitation (group three) had longer intensive care unit stays (p = 0.014) and increased incidence of postoperative renal failure when compared with group one (p = 0.039). Total transfusions were lowest in patients who received rFVIIa early in the course of resuscitation (group one) (median, two [interquartile range (IQR), 1-4.75]) and highest in group three (median, 11 [IQR, 8-14]; p < 0.001). Subsequent blood product transfusions after rFVIIa administration were highest in group two (p = 0.003); however, the median for all three groups was two products. There were no differences in thrombosis, reexplorations, or mortality in any of the groups. CONCLUSIONS: This study identified no differences in adverse outcomes based on timing of administration of low-dose rFVIIa for cardiac surgical bleeding defined by stage of resuscitation, but the benefits of early administration remain unclear.