Expiratory Positive Airway Pressure Research Articles

Effects of expiratory positive airway pressure vs continuous positive airway pressure in conscious, spontaneously breathing dogs.

The purpose of this study was to compare the cardiopulmonary effects of expiratory positive airway pressure (EPAP) and continuous positive airway pressure (CPAP) in conscious, spontaneously breathing dogs. Nine conscious dogs with elec- tromagnetic flow probes on their pulmonary arteries, catheters in their left atria and pulmo- nary arteries, and chronic tracheostomies, stood partially supported by slings, and breathed 100% oxygen through endotracheal tubes, pneumotachographs, and nonrebreathing valves which were part of either an EPAP or CPAP system. The effects of EPAP only were studied on four dogs while five were exposed to both EPAP and CPAP. After a 20-min control period, they breathed through either the EPAP or CPAP system for 10 min each under 5-, lo-, 15, and 20-cm H,O airway pressure. The mean pulmonary artery pressure, mean left atrial pressure, pulmonary vascular resistance, and minute ventilation were found to be significantly higher in the CPAP-treated group. Stroke volume and cardiac output were significantly higher in the EPAP-treated group. Both groups showed a significant carbon dioxide retention. Positive end-expiratory pressure, in conjunction with mechanical ventilation, is often used in the treatment of patients with pulmonary edema and adult respiratory distress syndrome. One potential disad- vantage of this therapy is a decrease in car- diac output (1 - 3).

Lung Volumes, Mechanics, and Oxygenation during Spontaneous Positive-Pressure Ventilation

To determine if continuous positive airway pressure (CPAP) or expiratory positive airway pressure (EPAP) is superior for achieving or maintaining effective lung volume in spontaneously breathing critically ill patients in acute respiratory failure, the authors measured functional residual capacity (FRC), airway and esophageal pressures, and arterial oxygen tensions when CPAP and EPAP were 5 and 10 cm H2O. Arterial oxygenation, FRC, and transpulmonary pressure at end-expiration were greatest when CPAP was 10 cm H2O. Lung compliance did not change. The authors conclude that CPAP at 10 cm H2O is the more effective technique, either because it allows relaxation of chest wall musculature on expiration, or because EPAP at 10 cm H2O increases chest wall muscle tone.

A new, microprocessor device for mean airway pressure measurement.

Accurate assessment of mean airway pressure (PAW) during controlled mechanical ventilation (CMV), intermittent mandatory ventilation (IMV), continuous positive airway pressure (CPAP), and expiratory positive airway pressure (EPAP) or spontaneous PEEP (sPEEP), or combinations thereof can be electronically determined with the Novametrix Pneumogard Model 1230 Ventilator Monitor. Measurement of PAW provides information on the interactions of airway pressure hemodynamics and respiratory function.

Use of positive airway pressure without endotracheal intubation

Continuous positive airway pressure (CPAP) and expiratory positive airway pressure (E-PAP) may be used safely without endotracheal intubation in patients with acute respiratory failure when strict selection criteria are adhered to. The therapy should be titrated to reduce intrapulmonary shunting, improve PaO2, and reduce FIO2. Other considerations include balancing oxygen consumption against cardiac output and oxygen transport. Absolute or relative indications for abandoning the technique and using endotracheal intubation with mechanical ventilatory support include unrelenting hypoxia, patient exhaustion, rising PaCO2, development of metabolic acidosis, presence of ventricular arrhythmias, and inability to protect the airway.

The Effects of Expiratory Positive Airway Pressure on Functional Residual Capacity in Normal Subjects

The Effects of Expiratory Positive Airway Pressure on Functional Residual Capacity in Normal Subjects

The effects of expiratory positive airway pressure on functional residual capacity in normal subjects

Functional residual capacity (FRC) was determined by constant volume, whole body plethysmography in seven normal subjects under resting conditions and following the addition of increasing levels of expiratory positive airway pressure (EPAP). There was a significant increase in FRC in six of the seven subjects studied. Grouped data showed a progressive increase in FRC with increasing EPAP (p less than 0.01). The highest level of EPAP (15 cm H2O) was associated with a 20% increase in FRC. We have been able to confirm that EPAP provides a simple and effective method of increasing FRC which could be applied to the treatment of conditions characterized by temporary and reversible reduction in lung volume.