Oxygenation and ventilation characteristics in obese sedated dogs before and after weight loss: A clinical trial

This prospective clinical study examined the effect of obesity and subsequent weight loss on oxygenation and ventilation during deep sedation in pet dogs. Data from nine dogs completing a formalised weight loss programme were evaluated. Dual-energy X-ray absorptiometry (DEXA) was used to quantify body fat mass prior to and after weight loss. Dogs were deeply sedated and positioned in dorsal recumbency. Sedation was scored using a semi-objective scheme. As part of the monitoring of sedation, arterial oxygen partial pressure (PaO₂) and arterial carbon dioxide partial pressure (PaCO₂) were measured after 10min in dorsal recumbency. Oxygen saturation of haemoglobin (SpO₂) was monitored continuously using pulse oximetry, starting oxygen supplementation where indicated (SpO₂2 increased from 27.9±19.2kPa to 34.8±24.4kPa, while FiO₂ decreased from 0.74±0.31 to 0.66±0.35. Morphometric measurements improved significantly after weight loss. PaO₂/FiO₂ (inspired oxygen fraction) and Pa/AO₂ (ratio of PaO₂ to alveolar PO₂) also improved significantly, but there was no change in f-shunt and PaCO₂ after weight loss. On multiple linear regression analysis, all oxygen indices were negatively associated with thoracic fat percentage. In conclusion, obesity decreases oxygenation in dogs during deep sedation. Oxygenation status improves with successful weight loss, but ventilation is not influenced by obesity.