Positive end-expiratory pressure during colic surgery in horses: 74 cases (1986-1988).

This study looked at the effects of positive end-expiratory pressure (PEEP) on arterial oxygen levels in horses undergoing colic surgery. The findings suggest that while PEEP can increase arterial oxygen tensions, it can also cause cardiovascular depression and reduced arterial blood pressure, requiring additional interventions.

Positive End-Expiratory Pressure (PEEP) in Horse Colic Surgery

• The research investigated the role of positive end-expiratory pressure (PEEP) in increasing the arterial oxygen tensions in horses undergoing colic surgery. Colic in horses is a severe, often emergency ailment of the digestive system that can cause extreme discomfort and can lead to sudden death.
• Anesthesia was induced in 74 horses who then underwent ventilation with PEEP. The main aim was to analyze if PEEP can elevate the levels of oxygen in the arterial blood (PaO2).

Effects of PEEP

• For 28 horses that initially had a PaO2 less than 70 mm of Hg, introducing PEEP increased the arterial oxygen values to an average of 173 +/- 24 mm of Hg. The oxygen content in the arterial blood rose from 14.1 +/- 0.05 ml/dl to 17.2 +/- 0.05 ml/dl.
• In the other 46 horses, PEEP elevated the mean PaO2 from 101 +/- 6 mm of Hg to 194 +/- 15 mm of Hg. The arterial oxygen content in these horses increased from 14.9 +/- 0.09 ml/dl to 16.9 +/- 0.07 ml/dl.

Associated Complications

• While PEEP was effective in increasing the arterial oxygen levels, it also led to cardiovascular depression in 54 horses after its application. In addition, a decrease in arterial blood pressure was observed in these animals.
• To maintain the mean arterial blood pressure above 60 mm of Hg, these horses required the use of pressors (n=8), inotropes (n=32), or both (n=14).

Conclusion and Clinical Implications

• Despite the observed cardiovascular depression and reduced arterial blood pressure, the study suggests that PEEP could be useful in clinical treatment of arterial hypoxemia in horses when used along with pharmacologic support for blood pressure.
• This research provides insight into the potential benefits and challenges of using PEEP in equine surgeries, furthering our understanding of anesthetic practices in veterinary medicine.