Evaluation of respiratory volume monitoring (RVM) to detect respiratory compromise in advance of pulse oximetry and help minimize false desaturation alarms.

BACKGROUND: Monitoring respiratory function is important. By continuously monitoring respiratory volumes, respiratory depression could be identified before hypoxemia and drive earlier intervention. Here, we evaluate the temporal relationship of respiratory volume monitoring (providing real-time minute ventilation [MV], tidal volume, and respiratory rate in nonintubated patients) to hypoxemic episodes and its potential to help classify true vs false desaturations (related to patient movement/probe dislodgement). METHODS: Respiratory volume monitoring data, oxygen saturation (SpO2), oxygen supplementation, and opioid use were analyzed in 259 patients following orthopedic surgery. Detection of "low MV" (<40% of predicted MV) in advance of low SpO2 (<90%) was used to classify true and false desaturations. Patients were also stratified based on opioid use and development of low MV. Patient's length of stay (LOS) and number of SpO2 alarms were compared across groups (± opioids; ± low MV). RESULTS: The electronic health records reported 113 SpO2 alarms; 105 (93%) not preceded by low MV and considered false. Low MV preceded the eight true desaturations by 12.8 ± 2.8 minutes. One hundred ninety-eight patients (76%) of 259 experienced one or more low MV events. Patients with low MV had significantly longer postanesthesia care unit (PACU) LOS than those maintaining "adequate MV": 2.8 ± 0.1 hours vs. 2.4 ± 0.1 hours (p < 0.001). Patients receiving opioids had increased likelihood of low MV (69% vs. 80%; p < 0.05) and had significantly longer PACU LOS than those without opioids (2.9 ± 0.1 hours vs. 2.3 ± 0.1 hours; p < 0.001). In the opioid group, PACU LOS was 75% longer in patients developing low MV versus maintaining adequate MV (3.0 ± 0.1 hours vs. 1.7 ± 0.2 hours; p < 0.001). CONCLUSION: Respiratory volume monitoring can provide advanced warning of impending oxygen desaturation and potentially reduce the number of false SpO2 alarms. Opioid administration increased low MV events correlating with increased LOS. Respiratory volume monitoring can help clinicians individualize patient care, decrease false alarms, adjust opioid dosing, and increase PACU throughput. Similar benefits may translate to the general care floor and prehospital and posthospital environments. LEVEL OF EVIDENCE: Diagnostic study, level II.

Heparin anticoagulation in patients undergoing off-pump and on-pump coronary bypass surgery.

PURPOSE: The authors analyzed the coagulation data of patients who underwent on-pump coronary artery bypass graft (CABG) or off-pump coronary artery bypass surgery (OPCAB) in a randomized prospective trial. METHODS: CABG and OPCAB patients received heparin anticoagulation at 400 U x kg(-1), and 180 U x kg(-1) plus 3000 U every 30 min, respectively. In addition, OPCAB patients received a rectal aspirin, 650 mg, during the procedure. Perioperative coagulation test results (platelet count, fibrinogen, prothrombin time, partial thromboplastin time [PTT], activated clotting time [ACT], and thromboelastography [TEG; Haemoscope] were collected from CABG (n = 99) and OPCAB (n = 98) patients. Residual heparin activity after protamine was measured, using an anti-activated factor X (Xa) assay, in 10 patients from each group. RESULTS: Our study showed that the current anticoagulation regimen in the OPCAB patients achieved a peak ACT of 445 +/- 73 s, and it preserved platelet counts and fibrinogen levels. A residual heparin effect was detected, with residual anti-Xa heparin activity of 0.2 U x ml(-1) up to 2 h after surgery in the OPCAB group. Despite the residual anticoagulation, the OPCAB group had a similar TEG index of native blood, postoperative chest tube drainage, and non-erythrocyte transfusion rate as compared with the CABG group. CONCLUSION: We have shown that the heparin anticoagulation regimen in OPCAB patients does not lead to an immediate hypercoagulable state. Total doses of heparin and protamine were lower in the OPCAB group compared with the CABG group, and there was a residual heparin effect on TEG and PTT in the early postoperative period in the OPCAB group.

Pulmonary outcomes of off-pump vs on-pump coronary artery bypass surgery in a randomized trial.

STUDY OBJECTIVES: Comparison of pulmonary outcomes after off-pump coronary artery bypass (OPCAB) vs on-pump coronary artery grafting with cardiopulmonary bypass (CABG/CPB). STUDY DESIGN: We examined preoperative and postoperative respiratory compliance, fluid balance, hemodynamics, arterial blood gases, chest radiographs, spirometry, pulmonary complications, and time to extubation in a prospective trial of 200 patients randomized to OPCAB vs CABG/CPB performed by one surgeon. RESULTS: One CABG/CPB patient and two OPCAB patients required mitral valve repair or replacement and were withdrawn. After three crossovers from CABG/CBP to OPCAB and one crossover from OPCAB to CABG, 97 CABG/CPB patients and 100 OPCAB patients remained. There were no significant preoperative demographic differences between groups. Postoperative compliance was reduced more after OPCAB than after CABG/CPB (- 15.4 +/- 10.7 mL/cm H(2)O vs - 11.2 +/- 10.1 mL/cm H(2)O [mean +/- SD]; p = 0.007), associated with rotation of the heart into the right chest to perform posterolateral bypasses (p < 0.001) and the concomitant increased fluid requirements necessary to maintain hemodynamic stability during rotation of the heart. In addition to higher intraoperative fluid intake (4,541 +/- 1,311 mL vs 3,585 +/- 1,033 mL, p < 0.0001), OPCAB patients had higher intraoperative fluid balance (3,903 +/- 1,315 mL vs 1,772 +/- 1,373 mL, p < 0.0001), and higher postoperative pulmonary arterial diastolic pressure (15.0 +/- 5.5 mm Hg vs 11.8 +/- 5.2 mm Hg, p < 0.0001) and central venous pressure (10.4 +/- 4.5 mm Hg vs 8.4 +/- 4.7 mm Hg, p < 0.0001). Despite lower compliance, immediate postoperative Pao(2) on fraction of inspired oxygen of 1.0 (275 +/- 97 torr vs 221 +/- 92 torr, p = 0.001) was higher after OPCAB and extubation was earlier (p = 0.001). Postoperative chest radiographs, spirometry, mortality, reintubation, or readmission for pulmonary complications were not different between groups. CONCLUSIONS: Compared to CABG/CPB, OPCAB was associated with a greater reduction in postoperative respiratory compliance associated with increased fluid administration and rotation of the heart into the right chest to perform posterolateral grafts. OPCAB yielded better gas exchange and earlier extubation but no difference in chest radiographs, spirometry, or rates of death, pneumonia, pleural effusion, or pulmonary edema.

Off-pump vs conventional coronary artery bypass grafting: early and 1-year graft patency, cost, and quality-of-life outcomes: a randomized trial.

CONTEXT: Previous trials of off-pump coronary artery bypass (OPCAB) have enrolled selected patients and have not rigorously evaluated long-term graft patency. A preliminary report showed OPCAB achieved improved inhospital outcomes, similar completeness of revascularization, and shorter lengths of stay compared with conventional coronary artery bypass grafting (CABG). OBJECTIVE: To assess graft patency, clinical and quality-of-life outcomes, and cost among patients while in the hospital and at 1-year follow-up. DESIGN, SETTING, AND PATIENTS: Randomized controlled trial of patients unselected for coronary anatomy, ventricular function, or comorbidities between March 10, 2000, and August 20, 2001, at a US academic center. A total of 200 patients were enrolled; 3 patients were withdrawn after randomization for mitral valve repair or replacement. Follow-up was complete for 197 patients at 30 days; 185 at 1 year. INTERVENTIONS: One surgical session consisting of elective OPCAB or CABG with cardiopulmonary bypass. The surgeon had extensive experience performing off-pump surgery; patients were subsequently managed by blinded protocols. MAIN OUTCOME MEASURES: Coronary angiography documented graft patency prior to hospital discharge and at 1 year; health-related quality of life; and cost of the index and subsequent hospitalization(s). RESULTS: Graft patency was similar for OPCAB and conventional CABG with cardiopulmonary bypass at 30 days (absolute difference, 1.3%; 95% confidence interval [CI], -0.66% to 3.31%; P =.19) and at 1 year (absolute difference, -2.2%; 95% CI, -6.1% to 1.7%; P =.27). Rates of death, stroke, myocardial infarction, angina, and reintervention were similar at 30 days and 1 year. There were no significant differences in health-related quality of life. Mean total hospitalization cost per patient at hospital discharge was 2272 dollars (95% CI, 755 dollars-3732 dollars) less for OPCAB (P =.002) and 1955 dollars (95% CI, -766 dollars to 4727 dollars) less at 1 year (P =.08). CONCLUSIONS: In this randomized single-surgeon trial among unselected patients with angiographic follow-up, OPCAB achieved similar graft patency in the hospital and at 1 year. Cardiac outcomes and health-related quality of life at 30 days and 1 year were similar and patients incurred a lower cost. OPCAB may provide complete revascularization that is durable and cost-effective.