Journal of clinical monitoring and computing
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J Clin Monit Comput · Dec 2011
Randomized Controlled TrialSkin conductance for monitoring of acute pain in adult postoperative patients: influence of electrode surface area and sampling time.
Aim of this prospective randomized study was to determine the influence of the electrode surface area and sampling time on the accuracy of the number of fluctuations in skin conductance per second to distinguish different states of acute pain. These methodological issues have been previously suggested as an explanation for contradictory data related to the accuracy of the skin conductance monitor. A total of 541 pain ratings on a numeric rating scale (0-10) were obtained from 120 adult postoperative patients. ⋯ However, the latter was found improved when the smaller surface area electrodes were used. A combination of small surface area electrodes and a 30 s sampling time resulted in the highest area under the curve in the receiver operating curve analysis of the method to identify states of moderate to severe pain (numeric rating scale > 3): 0.68 vs. e.g. 0.55 [data from all patients combined]). We conclude that the type of electrodes used but only to a lesser degree the sampling time influence the accuracy of the number of fluctuations in skin conductance per second to identify states of moderate or severe postoperative pain.
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J Clin Monit Comput · Dec 2011
Impact of central hypovolemia on photoplethysmographic waveform parameters in healthy volunteers part 2: frequency domain analysis.
The photoplethysmographic (PPG) waveforms are modulated by the respiratory, cardiac and autonomic nervous system. Lower body negative pressure (LBNP) has been used as an experimental tool to simulate loss of central blood volume in humans. The aim of our research is to understanding PPG waveform changes during progressive hypovolemia. ⋯ The pulse oximeter waveform contains a complex mixture of the effect of cardiac, venous, autonomic, and respiratory systems on the central and peripheral circulation. The occurrence of autonomic modulation needs to be taken into account when studying signals that have their origins from central sites (e.g. ear and forehead).
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J Clin Monit Comput · Dec 2011
Pulse oximetry saturation patterns detect repetitive reductions in airflow.
Postoperative patients exhibiting signs or symptoms of obstructive sleep apnea (OSA) have been identified to be at increased risk for respiratory compromise. One of the key markers associated with OSA is repetitive reductions in airflow (RRiA). A real-time pulse oximeter saturation pattern recognition algorithm (OxiMax SPD™ intended for adult in-hospital use only) designed to detect specific signatures in the SpO(2) trend associated with RRiA may provide caregivers early indication of its presence so they can treat the patient appropriately. The purpose of our study was to test the performance of saturation pattern detection (SPD) in a clinical study targeting subjects with a high prevalence of RRiA. ⋯ The real-time SPD algorithm was able to detect episodes of RRiA in sleep lab patients with a high degree of sensitivity and specificity.
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J Clin Monit Comput · Dec 2011
A comprehensive, computer-model-based approach for diagnosis and treatment of complex acid-base disorders in critically-ill patients.
We have developed a computer-model-based approach to quantitatively diagnose the causes of metabolic acid-base disorders in critically-ill patients. We use an interstitial-plasma-erythrocyte (IPE) model that is sufficiently detailed to accurately calculate steady-state changes from normal in fluid volumes and electrolyte concentrations in a given patient due to a number of causes of acid-base disorders. Normal fluid volumes for each patient are determined from their sex, height and weight using regression equations derived from measured data in humans. ⋯ We use critically-ill patient data to show how our new approach is more informative and much simpler to interpret as compared to the approaches of Siggaard-Andersen or Stewart. We demonstrate how the model can be used at the bedside to diagnose acid-base disorders and suggest appropriate treatment. Hence, this new approach gives clinicians a new tool for diagnosing disorders and specifying fluid-therapy options for critically-ill patients.
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J Clin Monit Comput · Dec 2011
Capability of a new paediatric oesophageal Doppler monitor to detect changes in cardiac output during testing of external pacemakers after cardiac surgery.
The Cardio QP™ oesophageal Doppler monitor measures the velocity time integral of the blood flow in the descending aorta. Based on system integrated normograms of the aortic cross-sectional area of a paediatric population, the cardiac output is calculated and displayed. ⋯ The Cardio QP™ seems to be capable of detecting slight changes in cardiac output.