Comparison of alveolar ventilation, oxygenation, pressure support, and respiratory system resistance in response to noninvasive versus conventional mechanical ventilation in foals.

The research article investigates the effectiveness of noninvasive mask mechanical ventilation compared to traditional endotracheal mechanical ventilation in foals under anesthesia. The study found that both methods had similar physiological effects, but the mask method resulted in slightly higher carbon dioxide levels, suggesting the possibility of adjusting ventilation strategies to reduce this.

Research Methodology

• The research was conducted using a crossover design, which allowed the researchers to compare the response of the foals to the two ventilation techniques, noninvasive mask mechanical ventilation (NIMV) and endotracheal mechanical ventilation (ETMV).
• Measurements for various physiological markers were taken during the study. These included arterial pH, oxygen saturation, end-tidal CO2 tension, airway pressures, total respiratory system resistance, and positive end-expiratory pressures (PEEP).
• The only variables in the experiment were the tidal volume or PEEP. Tidal volume refers to the amount of air that moves in and out of the lungs during normal breathing, while PEEP is the pressure in the lungs above atmospheric pressure that exists at the end of exhalation.

Research Findings

• Results showed that using NIMV led to significantly higher PaCO2 and pH levels compared to ETMV, while oxygenation (PaO2) was slightly lower.
• The peak airway pressure was similar between the two methods, but the flow of air during exhalation (peak expiratory flow) was significantly lower for NIMV and total respiratory resistance was higher at every level of tidal volume.
• Furthermore, PEEP delivery was slightly more effective with ETMV than NIMV.
• The research concluded that although physiologic effects with the use of NIMV and ETMV are similar, NIMV contributes to a higher dead space due to the nasal cavities and the mask, leading to higher carbon dioxide levels (hypercapnia).
• The researchers suggest adjusting the ventilation strategies such as increasing the volume of air moved per breath (tidal volume) or using pressure-cycled ventilation to reduce hypercapnia when using NIMV.

Potential Applications

• Given the findings, the researchers suggest that NIMV could be suitable for certain foals, such as those with hypoventilation and minimal changes in lung compliance.
• It could be considered for use during weaning from endotracheal mechanical ventilation, or for short-term ventilation in weak foals.