Intraoperative Protective Mechanical Ventilation in Dogs: A Randomized Clinical Trial

Abstract

ObjectiveTo evaluate gas exchange, respiratory mechanics, and hemodynamic impact of mechanical ventilation with low tidal volume (VT) in dogs with the use of positive end-expiratory pressure (PEEP) or preceded by alveolar recruitment maneuver (ARM).Study DesignProspective randomized clinical trial.AnimalsTwenty-one healthy client-owned mesocephalic healthy dogs, 1–7 years old, weighing 10–20 kg, and body condition scores 4–6/9 admitted for periodontal treatment.MethodsIsoflurane-anesthetized dogs in dorsal recumbency were ventilated until 1 h with a volume-controlled ventilation mode using 8 mL kg−1 of VT. The dogs were distributed in 2 groups: in the ARM group, PEEP starts in 0 cmH2O, increasing gradually 5 cmH2O every 3 min, until reach 15 cmH2O and decreasing in the same steps until 5 cmH2O, maintaining this value until the end; and PEEP group, in which the pressure 5 cmH2O was instituted from the beginning of anesthesia and maintained the same level up to the end of the anesthesia. Cardiopulmonary, metabolic, oxygenation parameters, and respiratory mechanics were recorded after the anesthesia induction (baseline—BL), 15, 45, and 75 min after BL and during the recovery.ResultsThe ARM increased the static compliance (Cst) (15 min after baseline) when compared with baseline moment (24.9 ± 5.8 mL cmH20−1 vs. 20.7 ± 5.4 mL cmH20−1–p = 0.0364), oxygenation index (PaO2/FIO2) (505.6 ± 59.2 mmHg vs. 461.2 ± 41.0 mmHg—p = 0.0453) and reduced the shunt fraction (3.4 ± 2.4% vs. 5.5 ± 1.6%—p = 0.062). In the PEEP group, no statistical differences were observed concerning the variables evaluated. At the beginning of the evaluation, the driving pressure (DP) before ARM was significantly greater than all other evaluation time points (6.9 ± 1.8 cmH20).Conclusions and Clinical RelevanceThe use of 8 mL kg−1 of VT and 5 cmH20 PEEP without ARM maintain adequate oxygenation and mechanical ventilation in dental surgeries for up to 1 h. The use of ARM slightly improved compliance and oxygenation during the maneuver.

Severe Hypercapnia during Anaesthesia under Mechanical Ventilation in Two Paediatric Patients

“…A low V T is used in humans because it has been proven that lung protective strategies reduce the risk of postoperative pulmonary complications [1]. In veterinary medicine, a recent study in healthy dogs, positioned in lateral recumbency and without an NMBA being used, evaluated the clinical feasibility of a V T of 8 mL/kg; the study concluded that this volume was sufficient to maintain normocapnia; however, this volume was not compared with other V T values [8]. The use of a low V T in dogs is still controversial, and there is evidence that volumes of 15 mL/kg are considered more appropriate to avoid hypercapnia [9][10][11].…”

Nasal anatomy and sniffing in respiration and olfaction of wild and domestic animals

“…Dogs come in a variety of breeds and have the largest variation in body size of all terrestrial vertebrates (34). Dogs have often been selected as surrogate models for humans in inhalation and lung function tests (35)(36)(37). A recent review of canine olfaction can be found in Kokocińska-Kusiak et al (38), which surveyed the physiological mechanisms and anatomical features that are implicated in the process of detecting and identifying odors.…”