USE OF POSITIVE-PRESSURE VENTILATION IN DOGS AND CATS - 41 CASES (1990-1992)

Intermittent positive-pressure ventilation (PPV) is an invasive means of respiratory support that is indicated in animals with central and p eripheral neuromuscular disease, as well as in those with primary diso rders of the lung parenchyma. We reviewed the medical records of 34 do gs and 7 cats treated with PPV. The animals could be allotted to 2 gro ups; group 1 (21/41) had primary failure of ventilation attributable t o neuromuscular disease or airway obstruction, and group 2 (20/41) had primary pulmonary parenchymal disease. Mean inspiratory time was 1.02 +/- 0.2 seconds (range, 0.6 to 1.5 seconds). Mean inspiratory flow wa s 26.9 +/- 18.5 L/min (range, 7 to 87 L/min), and was positively corre lated with body weight (R = 0.57). Mean set respiratory rate was 19.6 +/- 10 breaths/min (range, 5 to 60 breaths/min), with mean tidal volum e of 15.5 +/- 6.2 ml/kg of body weight. Positive end-expiratory pressu re (PEEP) was required in 14 of 20 dogs in group 2. Mean peak airway p ressure in group 1 was 21.6 +/- 6.3 cm of H2O, whereas in group 2 it w as 32.9 +/- 12.5 cm of H2O. The higher peak airway pressure in group-2 dogs reflected poor lung compliance and the use of PEEP in dogs with parenchymal lung disease. Mean duration of PPV was 28.2 +/- 29.4 hours (range, 2 to 137 hours). The overall survival rate was 39% (16/41). F actors that appeared to correlate with survival included age, with hig her mortality in animals < 1 year old or > 11 years old (P < 0.01); bo dy weight, with mortality highest in animals < 10 hg (P < 0.05); reaso n for ventilation, with survival in group 1 being 57%, and in group 2, 20%; and development of complications, with 28% of animals that devel oped major complications surviving, compared with 48% of those that di d not develop major complications, live major complications of PPV wer e documented: pneumothorax and pneumonia. Twelve of 41 animals develop ed pneumothorax and had been ventilated by use of peak airway pressure s > 25 cm of H2O, or PEEP, An additional 6 animals developed subclinic al pneumonia during treatment with PPV.