Cardiovascular effects of intermittent positive pressure ventilation in the anesthetized horse.

The research examines how intermittent positive pressure ventilation (IPPV), a respiratory support method, impacts the heart function of anesthetized horses. Interestingly, the study unraveled that there’s a possible decrease in cardiac activity in horses under anesthesia and receiving IPPV, presenting a significant insight for veterinary practitioners.

Research Design and Methodology

• For the study, 15 healthy, halothane-anesthetized mares were grouped into three sets (N = 5 each).
• The first set was allowed spontaneous ventilation (SV), the second received controlled ventilation with an end-inspiratory pressure of 20 cmH2O (CV20), and the third group was given a 25 cmH2O (CV25) inspiratory pressure.
• The researchers then monitored changes in the cardiac function of each group during the 120-minute anesthesia period.

Major Findings

• All groups had a gradual decline in cardiac activity over time, reinforcing the theory that IPPV may lessen cardiac output.
• After 105 minutes of anesthesia, the CV participants showed a cardiac output below half the pre-anesthetic value.
• Interestingly, the CV25 group faced a significantly noticeable (p < 0.05) drop in cardiac output after 45, 90, and 120 minutes compared to the SV group.
• Contrarily, no significant difference was observed between the SV and CV20 groups over time.

Conclusion and Recommendations

• The research establishes that IPPV may cause cardiac output reduction. Therefore, necessary improvements are suggested for longer anesthesia durations with IPPV usage.
• The study suggests setting an end-respiratory pressure of 20 cmH2O during clinical use of halothane anesthesia as it causes a mild decrease in cardiac output even with slightly elevated PaCO2.