Pulmonary atelectasis in dogs during general anesthesia/Atelectasia pulmonar em caes durante anestesia geral

Pleural pressure is usually lower than pulmonary pressure. Therefore, the lungs tend to collapse and increase its distance from thoracic walls. At the beginning of 20th century, Pasteur described the pulmonary atelectasis, which develops during induction of anesthesia and persists to the postoperative period. It can contribute significantly to morbidity and to increase the medical expenses. In veterinary medicine, pulmonary atelectasis is not frequently diagnosed, which doesn't rule out the occurrence of this disease, since there are reports of atelectsasis in dogs. This pulmonary complication can be found in animals that breathe 80% to 100% oxygen in anesthetic procedures. Based on this information, the veterinary anesthesiologist is required to search for complementary knowledge regarding to pulmonary atelectasis. This study, therefore, aimed to describe some of the mechanisms involved in the development of atelectasis. It aimed also to familiarize the anesthesiologist to this not always well- understood physiological breathing change. Key words: fractional inspired oxygen, pulmonary collapse, shunt. A pressao intrapleural normalmente e menor que a pressao intrapulmonar. Consequentemente , os pulmoes tendem ao colapso e se retraem, afastando-se da parede toracica. No inicio do seculo XX, Pasteur descreveu a atelectasia pulmonar, que ocorre com frequencia durante a inducao anestesica, persiste no periodo pos-operatorio e pode contribuir de maneira significativa para a morbidade e o aumento nos gastos com medicamentos. Em medicina veterinaria, no entanto, a atelectasia nao e frequentemente diagnosticada, apesar de que isso nao implica afirmar que tal afeccao nao ocorra, visto que existem relatos do desenvolvimento desse quadro em caes e em outras especies. No contexto da anestesia geral, essa complicacao pulmonar pode ser encontrada em animais que respiram 80 a 100% de oxigenio. A partir dessas informacoes, torna-se necessario que o profissional da anestesiologia veterinaria obtenha conhecimentos complementares sobre o tema. Com este trabalho, objetivou- se descrever alguns dos mecanismos da atelectasia e seus pontos relevantes, de modo a familiarizar os profissionais quanto aos pormenores dessa importante, e nem sempre bem compreendida, alteracao fisiologica respiratoria. Palavras-chave: colapso pulmonar, fracao inspirada de oxigenio, shunt.