Journal of clinical monitoring and computing
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J Clin Monit Comput · Jan 2000
Monitoring of isoflurane and desflurane breakdown: interfering gases and infrared detection.
The reaction of isoflurane, enflurane or desflurane with dried CO2 absorbents produces carbon monixide (CO), a highly toxic gas which cannot be detected by gas monitors typically available in the operating room. Trifluoromethane (CHF3) is produced along with CO when this reaction occurs with isoflurane and desflurane, and can be detected by gas monitors. This study will determine the ability of a modified SAM module (Smart Anesthesia Multigas Module, GE/Marquette Medical Systems, Milwaukee, WI) to identify the presence of CHF3, and provide a clinically useful indirect warning of CO production. ⋯ We have shown that the SAM module is capable of measuring CHF3 due to anesthetic breakdown. With appropriate changes in the display programming and reference cell spectra the monitor would be able to provide an early warning of CO exposure, although the amount of CO would not be reported.
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J Clin Monit Comput · Jan 2000
Teaching respiratory physiology: clinical correlation with a human patient simulator.
In recent years students have increasingly objected to laboratory exercises involving animal subjects. We have replaced the valuable animal experiments with demonstrations using a full-scale human patient simulator. In small groups first-year medical students observe realistic clinical situations such as opioid-induced hypoventilation, pneumothorax, and pulmonary edema. ⋯ They practice interventions such as providing supplemental oxygen and mask ventilation, monitor the results, and develop a basic differential diagnosis and treatment plan. We utilize the clinical context to review fundamental concepts of respiratory physiology including the alveolar air equation and oxyhemoglobin dissociation curve. The students give these laboratory exercises uniformly superior evaluations.
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The measurement of exhaled pulmonary nitric oxide concentrations requires that contamination from the upper respiratory tract and inhaled gases be eliminated. This can be achieved with no risk in the clinical setting of intubated patients of all ages in the operating room or intensive care unit. Further modifications of the anesthetic/ventilatory circuit allow for accurate determination of tidal volume and minute ventilation.
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J Clin Monit Comput · Jan 2000
Discriminating between the effect of shunt and reduced VA/Q on arterial oxygen saturation is particularly useful in clinical practice.
There is an extensive literature on methods for discriminating between an increased shunt and a reduced ratio of ventilation to perfusion. In this review we prefer the terms "VA/Q" and "reduced or low VA/Q" rather than "V/Q inequality" to refer to the effects on arterial oxygenation of reducing V/Q below 0.8 to about 0.1. ⋯ However this review shows that, while an increased shunt and a decreased VA/Q both reduce arterial oxygen saturation (SaO2) at a particular inspired oxygen concentration (PIO2), the effect of shunt and reduced VA/Q have important clinical differences on the relationship between PIO2 and SaO2. The review also outlines a simple non-invasive method for measuring shunt and reduced VA/Q which illustrates the value of discriminating between them in clinical practice.