Verification and validation of physiology simulators.

In this paper we describe a general method to provide verification and validation of physiological simulators. We also present an application of this method and key results.

Patient repositioning and pressure ulcer risk--monitoring interface pressures of at-risk patients.

Repositioning patients regularly to prevent pressure ulcers and reduce interface pressures is the standard of care, yet prior work has found that standard repositioning does not relieve all areas of at-risk tissue in nondisabled subjects. To determine whether this holds true for high-risk patients, we assessed the effectiveness of routine repositioning in relieving at-risk tissue of the perisacral area using interface pressure mapping. Bedridden patients at risk for pressure ulcer formation (n = 23, Braden score <18) had their perisacral skin-bed interface pressures recorded every 30 s while they received routine repositioning care for 4-6 h.

Effects of turning on skin-bed interface pressures in healthy adults.

Aim: This paper is a report of a study of the effects of lateral turning on skin-bed interface pressures in the sacral, trochanteric and buttock regions, and its effectiveness in unloading at-risk tissue.

Background: Minimizing skin-support surface interface pressure is important in pressure ulcer prevention, but the effect of standard patient repositioning on skin interface pressure has not been objectively established.

Methods: Data were collected from 15 healthy adults from a university-affiliated hospital.

A longitudinal description of heart rate variability in 28--34-week-old preterm infants.

The purpose of this study was to longitudinally describe changes in heart rate variability (HRV) from 28 to 34 weeks postmenstrual age (PMA). A convenience sample of 31 low-risk preterm infants participated. HRV was quantified using a spectral analysis of heart periods and recorded during seven weekly test sessions from an electrocardiogram (ECG) signal.

An integrated coronary circulation teaching model.

Objectives: We present in this paper a model of the coronary circulation. This model is integrated with a model of the systemic circulation, and contains models for oxygen supply and demand.

Methods: Three compartments are created: one for the right ventricle, one for the epicardial segment of the left ventricle and one for the endo-cardial segment of the left ventricle.

The Stealth Station Image Guidance System may interfere with pulse oximetry.

Purpose: Interference on pulse oximetry can come from many sources. We found an additional source of interference from the Stealth Station. This article gives an overview of sources of pulse oximeter interference so that clinicians can better prevent them.

Opioid-induced respiratory depression: a mathematical model for fentanyl.

In this paper, respiratory depressant effects of fentanyl are described quantitatively by a mathematical model. The model is an extension of a previous one, which reproduces the human ventilatory control system on a physiological basis. It includes the following: three compartments for gas storage and exchange (lungs, body tissue, and brain tissue); the main mechanisms involved in ventilation control (peripheral chemoreceptors, central chemoreceptors, and the central hypoxic depression); and local blood flow regulation.

Comparative testing of pulse oximeter probes.

Unlabelled: The testing of pulse oximeter probes is generally limited to the integrity of the electrical circuit and does not include the optical properties of the probes. Few pulse oximeter testers evaluate the accuracy of both the monitor and the probe. We designed a study to compare the accuracy of nonproprietary probes (OSS Medical) designed for use with Nellcor, Datex-Ohmeda, and Criticare pulse oximeter monitors with that of their corresponding proprietary probes by using a commercial off-the-shelf pulse oximeter tester (Index).

Learning about new anesthetics using a model driven, full human simulator.

Objective: New pharmacological agents are introduced into medical practice at an ever-increasing pace. Teaching how to use new medications in the clinical setting presents educational challenges and puts patients at risk.

Methods: Patients and clinical settings in which remifentanil might provide clinical advantages over existing anesthetics were identified.