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Objective: Contrast-induced renal dysfunction is an iatrogenic complication that occurs more frequently in patients with preexisting renal dysfunction. A prospective, double-blind, randomized, placebo, controlled trial was completed to assess the efficacy of N-acetylcysteine in decreasing the incidence of contrast-induced renal dysfunction in patients with an acute coronary syndrome and renal insufficiency who underwent coronary angiography with or without percutaneous coronary intervention., Methods: With similar intravenous hydration protocols, 20 patients received N-acetylcysteine (treatment group) and 20 patients received placebo (control group) in a twice per day dosing regimen with one dose before and three doses after contrast media exposure., Results: The two groups were similar at baseline on demographic and clinical characteristics, and preexisting renal insufficiency. Contrast-induced renal dysfunction, defined as an increase in serum creatinine greater than 44 micromol/L (.5 mg/dL) and/or 25% above baseline within 48 hours, occurred in 7.5% of the cohort, with 2.5% in the treatment group, and 5% in the control group, for an absolute difference of 2.5%. There was no difference in serum creatinine or creatinine clearance at 24 hours or at 48 hours between the treatment and control groups., Conclusion: These results suggest that this cohort gained no added protection to renal function with the use of N-acetylcysteine.

Objective: The purposes of the study were to: (1) describe the aggregate strength of the relationship of arterial oxygen saturation as measured by pulse oximetry with the standard of arterial blood gas analysis as measured by co-oximetry, (2) examine how various factors affect this relationship, and (3) describe an aggregate estimate of the bias and precision between oxygen saturation as measured by pulse oximetry and the standard in vitro measures., Design: A meta-analysis was conducted., Sample: Seventy-four studies from 1976 to 1994 met the inclusion criteria of: (1) adult study population, (2) quantitative analysis of empirical data, and (3) bivariate correlations or bias and precision estimates between pulse oximeter and co-oximeter values., Results: There were a total of 169 oximeter trials on 41 oximeter models from 25 different manufacturers. Studies were conducted in various settings with a variety of subjects, with most being healthy adult volunteers. The weighted mean r, based on 39 studies (62 oximeter trials) for which the r statistic and number of data points were available, was 0.895 (var [r] = 0.014). Based on 23 studies (82 oximeter trials) for which bias and precision estimates and number of data points were available, the mean absolute bias and precision were 1.999 and 0.233, respectively. Several factors were found to affect the accuracy of pulse oximetry., Conclusion: Pulse oximeters were found to be accurate within 2% (+/- 1 SD) or 5% (+/- 2 SD) of in vitro oximetry in the range of 70% to 100% Sao2. In comparing ear and finger probes, readings from finger probes were more accurate. Pulse oximeters may fail to record accurately the true Sao2 during severe or rapid desaturation, hypotension, hypothermia, dyshemoglobinemia, and low perfusion states.