Evaluation of a pulse oximeter sensor tester.

OBJECTIVE: The Lightman is intended to test the optical and electrical properties of a pulse oximeter probe including the wavelength of the light emitting diode by means of a micro spectrometer. The aim of this study was to evaluate the ability of the Lightman to detect faulty pulse oximeter finger probes by testing the accuracy of the wavelength of the light emitting diode in isolation from the monitor. METHODS: The pulse oximeter measurements of arterial oxygen saturation from the "accurate" and "inaccurate" probes, as identified by the Lightman, were compared with arterial saturation determined by a co-oximeter. Data was analysed from 63 sets of measurements. In addition, we conducted a national survey to determine the testing procedures used by the Biomedical Engineering departments to evaluate the accuracy of pulse oximeter devices. RESULTS: The bias [95% limits of agreement] for accurate, over-reading and under-reading probes were 0.17% [3.6 to -3.3], 1.44% [5.4 to -2.5] and -1.6% [2.6 to -5.8] respectively. The response rate to the national survey was 75% (142/189); a pulse oximeter tester was used by 93/142 (65%) trusts. CONCLUSIONS: Our findings suggest that the Lightman can detect faulty probes and predict reasonably accurately the direction of the probe's error. The Lightman may be considered as a useful tool to assess the accuracy of pulse oximeters. The national survey highlighted a wide variation in the testing procedure utilised to evaluate the accuracy of pulse oximeters. Introduction of guidelines regarding the testing procedure would promote a uniform practice.

Opioid-sparing effects of diclofenac and paracetamol lead to improved outcomes after cardiac surgery.

OBJECTIVE: This study assessed the analgesic efficacy, side effects, time to extubation, and oxygenation of 3 analgesic regimens after coronary artery bypass surgery using diclofenac, paracetamol, and placebo suppositories. DESIGN: Prospective, randomized, double-blind, placebo-controlled study. SETTING: Referral center for cardiothoracic surgery at a university hospital. PARTICIPANTS: Sixty consenting adults scheduled for elective coronary artery bypass grafting (CABG). INTERVENTIONS: Patients were divided into 3 groups postoperatively: diclofenac/paracetamol: diclofenac, 100 mg rectally, and paracetamol, 1 g rectally. Diclofenac was repeated after 18 hours and paracetamol every 6 hours for 24 hours; diclofenac: diclofenac as in diclofenac/paracetamol, with placebos replacing paracetamol; and placebo: 2 placebo suppositories at same times as diclofenac/paracetamol. All patients received morphine patient-controlled analgesia. RESULTS: Twenty-four hour morphine consumption with diclofenac/paracetamol was 12 +/- 6 mg, diclofenac 22 +/- 13 mg, and placebo 37 +/- 15 mg (diclofenac/paracetamol and diclofenac, p = 0.0003 and p = 0.0159 compared with placebo). Patients in the placebo group had significantly greater pain scores at 12 and 24 hours compared with diclofenac/paracetamol and diclofenac. Extubation time was significantly prolonged in the placebo group compared with the diclofenac/paracetamol and diclofenac groups (mean [SD] minutes diclofenac/paracetamol, diclofenac, and placebo 478 [150], 487 [257], and 710 [326], respectively). Oxygenation following extubation was significantly lower in the placebo group compared with the diclofenac/paracetamol and diclofenac groups (mean [SD] mmHg: diclofenac/paracetamol, diclofenac, and placebo 175 [44], 157 [43], and 117 [22], respectively). Episodes of nausea and vomiting were significantly less in the diclofenac/paracetamol and diclofenac groups than in the placebo group (46% and 51% reduction, respectively). all groups had similar blood loss and change in serum creatinine. CONCLUSION: Diclofenac alone or with paracetamol has a significant opioid-sparing effect after CABG, producing more rapid extubation and better oxygenation.