Intensive care medicine
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Intensive care medicine · Jan 1992
Randomized Controlled Trial Comparative Study Clinical TrialComparison of hydrophobic heat and moisture exchangers with heated humidifier during prolonged mechanical ventilation.
Inspired gases must be warmed and humidified during mechanical ventilation. In a prospective randomized study we compared the performance of a heated humidifier (HH) (Draegger Aquaport) and a heat and moisture exchanger (HME) (Pall Filter BB 2215). A total of 116 patients requiring mechanical ventilation (Servo 900 C Siemens) were enrolled into the study and were randomly assigned to 2 groups. ⋯ This purely physical property is linked to the magnitude of the thermic gradient between the expired gases and the ambiant temperature. Performance impairment of PF in our study might be due to high ambiant temperature in the intensive care unit (usually around 28 degrees C) which reduces thermic gradient and water exchanges. We conclude that efficiency of PF may be weak in some conditions of ambiant temperature.
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Measurement of arterial oxygen saturation by pulse oximetry was performed in two patients with acute and chronic anaemia (haemoglobin concentrations: 2.9 mmol/l (4.7 g/dl) and 1.9 mmol/l (3.0 g/dl), respectively) using a Radiometer OXI and a Nellcor N-200 pulse oximeter. The two oximeters read alternating different values in the two patients. In conclusion, pulse oximeters are able to give a value for oxygen saturation even at extreme anaemia, and when a high value is given, it possibly reflects arterial oxygen saturation. The value of pulse oximetry in severe anaemia is discussed.
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Intensive care medicine · Jan 1992
Comparative StudyMonitoring of central venous oxygen saturation versus mixed venous oxygen saturation in critically ill patients.
Continuous monitoring of mixed venous (SvO2) and central venous (ScO2) oxygen saturation was compared in 7 critically-ill patients (Apache II score: 19 +/- 2.1) to determine whether or not information derived from ScO2 were reliable in clinical practice. Patients were catheterized with both a pulmonary artery (PA) and a central venous (CV) catheter, each of them mounted with fiberoptic sensors (Opticath PA Catheter P7110 and Opticath CV Catheter U440, Abbott). A total of 580 comparative measurements were obtained during periods without and with therapeutic interventions (drug-titration, bronchial suction, use of PEEP, changes in FiO2 ...). ⋯ There were poor correlations between the values during periods without (r = 0.48) and with therapeutic interventions (r = 0.62). Better, but still less than ideal, correlations were obtained with changes in SvO2 and ScO2 during periods without (r = 0.70) and with therapeutic interventions (r = 0.77). Although there is a need to develop a simple technique to monitor mixed venous oxygen saturation, the present study indicates that ScO2 monitoring was not reliable in the study patients.
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The development of the flexible, fiberoptic bronchoscope has made bronchoscopic examinations possible in ICU patients undergoing mechanical ventilation. Over the years, the number of such procedures has greatly increased, with both diagnostic and therapeutic objectives, such as performing difficult intubation, management of atelectasis and hemoptysis, diagnosis of nosocomial pneumonia in ventilated patients, and early detection of airway lesions in selected situations, such as high-frequency ventilation. The complication rate can be kept low if the endoscopist has a precise knowledge of the many pathophysiological and technical facets particular to bronchoscopy under these difficult conditions. This article reviews some of these aspects, in the light of our personal experience.
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Intensive care medicine · Jan 1992
A fibre optics system for the evaluation of airway pressure in mechanically ventilated patients.
The present study was intended to evaluate the "in vivo" endotracheal (ET) tube resistance and respiratory mechanics in mechanically ventilated patients with respiratory failure by using fiber optic catheters. ⋯ This study confirms that 48 h after the positioning of ET tubes the airflow resistance is significantly higher than might be expected from the "in vitro" data. The presence of the endotracheal tube can interfere with the evaluation of thoraco-pulmonary mechanics, particularly in dynamic conditions. The fiber optic system represents an interesting and simple tool for the evaluation of ET tube resistance and pulmonary mechanics in patients undergoing mechanical ventilation.