Effects of 12 and 17 cmH2O positive end-expiratory pressure applied after alveolar recruitment maneuver on pulmonary gas exchange and compliance in isoflurane-anesthetized horses

Successful management of hypoxaemia in a mule during general anaesthesia

“…36 A study in horses has shown PEEP values of 12 and 17 cmH 2 O after a recruitment manoeuvre to be adequate for improvement in A-aO 2 tension; however a PEEP of 7 cmH 2 O was not sufficient. 34 In the present case, a progressive increase in PaO 2 was recorded after the second lung recruitment with a PEEP of 20 cmH 2 O. Multiple studies have shown similar effects after treatment with modified OLC (mOLC).…”

Anaesthetic management of a bovine for ventral midline coeliotomy approach to hysterotomy

“…Therefore, a conservative PEEP level of 8 cmH 2 O was initially instituted and would have been titrated upward had the need arose. Although the minimum recommended PEEP level in horses is 10 cmH 2 O, 17 the application of 8 cmH 2 O PEEP in this case resulted in a clinically acceptable PaO 2 and the MAP remained within acceptable limits (70–90 mmHg) for the duration of anaesthesia.…”

“…Large animals, such as cattle and horses develop ventilation/perfusion (V/Q) mismatching within 20 min of induction of general anaesthesia, 14–16 represented by two extremes: ventilated but non‐perfused alveoli (V/Q = ∞) and perfused but non‐ventilated alveoli (V/Q = 0) 16 . In horses, where ventilation under anaesthesia has been extensively investigated, the latter scenario usually occurs (a reduction in the V/Q ratio) due to the weight of the abdominal viscera overlying the diaphragm and reduction in the tone of the respiratory muscles 15,17 . These factors result in the reduction of FRC such that alveolar closing volume exceeds FRC culminating in large areas of pulmonary atelectasis.…”

“…PEEP stabilises alveolar units by increasing FRC above the closing volume, thus preventing closure of the small airways and subsequent alveolar collapse 13 . The application of PEEP thereby improves V/Q matching and thus oxygenation and also may effect an increase in pulmonary compliance 13,14,17,23 …”

“…16 In horses, where ventilation under anaesthesia has been extensively investigated, the latter scenario usually occurs (a reduction in the V/Q ratio) due to the weight of the abdominal viscera overlying the diaphragm and reduction in the tone of the respiratory muscles. 15,17 These factors result in the reduction of FRC such that alveolar closing volume exceeds FRC culminating in large areas of pulmonary atelectasis. Thus, the V/Q mismatching in horses under anaesthesia is due to the development of atelectasis when the animal is positioned in either lateral or dorsal recumbency.…”