Continuous calculation of intratracheal pressure in the presence of pediatric endotracheal tubes

Guttmann, J.; Kessler, Volker; Mols, Georg; Hentschel, Roland; Haberthür, Christoph; Geiger, K.

doi:10.1097/00003246-200004000-00018

Cited by 65 publications

(78 citation statements)

References 31 publications

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“…P/V loops were constructed from FOPT, reference pressure transducer, and volume signal, and the areas of the P/V loops were compared. Tracheal pressure was calculated according to Guttmann et al (2) and compared with actual measured pressure.…”

Section: Experimental and Clinical Testingmentioning

confidence: 99%

“…In the adult setting tracheal pressure measurement is accomplished by introducing an air-or liquid-filled catheter into the ETT and connecting it to a conventional pressure transducer (1). In the pediatric setting it has generally been held to be impossible to use endotracheal catheters for continuous pressure measurement owing to the encroachment on cross-sectional area of the narrow pediatric tubes (2). Instead hydrodynamic models of varying complexity have been proposed for the calculation of tracheal pressure, i.e.…”

mentioning

confidence: 99%

“…the pressure fall across the ETT because of its resistance, based on measurements above the tube. Guttmann et al (2) proposed an equation of the pressure fall by combining linear and quadratic pressureflow dependency and inertance relating to volume acceleration. The equation makes use of two inspiratory and two expiratory constants calculated in a bench model for each ETT of specified length, curvature, and diameter.…”

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confidence: 99%

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Direct Measurement of Intratracheal Pressure in Pediatric Respiratory Monitoring

et al. 2002

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We describe a method based on a Fabry-Perot interferometer at the tip of an optic fiber with a diameter of 0.25 mm for direct measurement of tracheal pressure in pediatric respiratory monitoring. The response time of the pressure transducer and its influence on the resistance of pediatric endotracheal tubes (internal diameter, 2.5 to 5 mm) during constant and dynamic flow at different ventilator settings in a lung model were measured. The transducer was positioned at Ϫ1.5 (inside), 0, and ϩ1.5 cm (outside) relative to the tip of the endotracheal tube and compared with a reference pressure inside the trachea. The clinical application of the transducer was tested in five pediatric patients. The response time of the transducer was 1.3 ms. The influence of the fiberoptic transducer on tube resistance was negligible during constant flow in inspiratory and expiratory directions for all endotracheal tubes tested. There was no difference in pressure measurements with the transducer positioned at or 1.5 cm below or above the tip of the endotracheal tube during dynamic measurements. During clinical circumstances insertion of the fiberoptic transducer was easy, recordings were stable, and the safety of the patient was not jeopardized. The fiberoptic transducer provided a reliable and promising way of monitoring tracheal pressure in intubated pediatric patients. The presence of the probe did not interfere with either pressure-flow relationship or patient care and safety. The technique is proposed for monitoring of respiratory mechanics and calculation of changes in tube resistance caused by kinking and secretions. Respiratory monitoring in pediatric intensive care is currently represented by proximal P/V loops obtained in ventilator software or intensive care monitors using flowmeters placed near the connection between the ventilator system and ETT. This is obviously insufficient as information gained from such P/V loops mainly stems from ETT resistance and performance of ventilator valves. We have previously demonstrated that monitoring respiratory mechanics by direct measurement of tracheal pressure offers considerable advantages compared with monitoring based on either measurements obtained proximal to the tube or tracheal pressures calculated by subtracting pressure needed to overcome flow-dependent tube resistance. In the adult setting tracheal pressure measurement is accomplished by introducing an air-or liquid-filled catheter into the ETT and connecting it to a conventional pressure transducer (1). In the pediatric setting it has generally been held to be impossible to use endotracheal catheters for continuous pressure measurement owing to the encroachment on cross-sectional area of the narrow pediatric tubes (2). Instead hydrodynamic models of varying complexity have been proposed for the calculation of tracheal pressure, i.e. the pressure fall across the ETT because of its resistance, based on measurements above the tube. Guttmann et al. (2)

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Section: Experimental and Clinical Testingmentioning

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Direct Measurement of Intratracheal Pressure in Pediatric Respiratory Monitoring

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“…2. Inspiratory tracheal pressure (p trach-calc ) is calculated according to (2) as the difference between airway pressure p aw and the pressure drop across the endotracheal tube ⌬Pett:…”

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confidence: 99%

“…With k 1 and k 2 being the constants according to (2). How do the authors explain that using Equation 1 they could arrive at a decelerating pressure profile for inspiratory p trach as presented in Figure 8?…”

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confidence: 99%