Use of near-infrared spectroscopy as a physiologic monitor for intra-abdominal hypertension.

BACKGROUND: Intra-abdominal hypertension (IAH) is increasingly recognized as an important parameter in critically ill (ICU) patients. IAH affects perfusion to all abdominal components including the abdominal wall (AW). Near infrared spectroscopy (NIRS) measures changes in three chromophores including oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (Hb), and cytochrome aa3 (Cyt), providing information concerning dysoxia. We sought to examine whether NIRS measurement of the AW was safe, and correlated with intra-abdominal pressure (IAP) in ICU patients. METHODS: A NIU-Pro001 system recorded NIRS data over 24 hours from the AW of 9 ICU patients at risk for IAH. IAP was recorded from the bladder. Changes in chromophore values are interpolated from best-fit polynomial curves. RESULTS: Sixty-six paired IAP and NIRS readings were taken from 9 ICU (4-12 observations/patient) patients. No measurement related adverse reactions occurred. The mean (range) first values measured in these patients were; IAP 17.2 mm Hg (9-31); HbO2 0.41 micromol/L (-8.4 to 7.6); Hb 2.6 micromol/L (-3.1 to 12.2); and Cyt 0.65 micromol/L (-3.4 to 4.8). A significant, inverse (or negative) association was found between DeltaNIRS HbO2 level and DeltaIAP (coefficient, -0.1588; p = 0.008). No association was found between DeltaNIRS Hb or DeltaCyt and DeltaIAP. CONCLUSION: NIRS of the AW appears safe. NIRS measurement of changes in HbO2 appears to be associated with DeltaIAP, and warrant further study in greater numbers of ICU patients with more frequent IAP readings, over longer periods of critical illness.

A randomized, controlled trial of the use of pulmonary-artery catheters in high-risk surgical patients.

BACKGROUND: Some observational studies suggest that the use of pulmonary-artery catheters to guide therapy is associated with increased mortality. METHODS: We performed a randomized trial comparing goal-directed therapy guided by a pulmonary-artery catheter with standard care without the use of a pulmonary-artery catheter. The subjects were high-risk patients 60 years of age or older, with American Society of Anesthesiologists (ASA) class III or IV risk, who were scheduled for urgent or elective major surgery, followed by a stay in an intensive care unit. Outcomes were adjudicated by observers who were unaware of the treatment-group assignments. The primary outcome was in-hospital mortality from any cause. RESULTS: Of 3803 eligible patients, 1994 (52.4 percent) underwent randomization. The base-line characteristics of the two treatment groups were similar. A total of 77 of 997 patients who underwent surgery without the use of a pulmonary-artery catheter (7.7 percent) died in the hospital, as compared with 78 of 997 patients in whom a pulmonary-artery catheter was used (7.8 percent)--a difference of 0.1 percentage point (95 percent confidence interval, -2.3 to 2.5). There was a higher rate of pulmonary embolism in the catheter group than in the standard-care group (8 events vs. 0 events, P=0.004). The survival rates at 6 months among patients in the standard-care and catheter groups were 88.1 and 87.4 percent, respectively (difference, -0.7 percentage point [95 percent confidence interval, -3.6 to 2.2]; negative survival differences favor standard care); at 12 months, the rates were 83.9 and 83.0 percent, respectively (difference, -0.9 percentage point [95 percent confidence interval, -4.3 to 2.4]). The median hospital stay was 10 days in each group. CONCLUSIONS: We found no benefit to therapy directed by pulmonary-artery catheter over standard care in elderly, high-risk surgical patients requiring intensive care.