Practical management of severe lung disease and injury (Proceedings)
The principles of management of patients with severe lung disease and injury are summarized and the cases depicting the use if these management techniques are presented.
Provide oxygen early and calm the patient with drugs so that they do not become more stressed.Cats and small dogs that arrive should be immediately placed in a small box and this box flooded with high flow – 20-Liter per minute – of oxygen. It is preferred if the "struggling to breath pet be actually place in a cardboard box at the scene, before travel. If travel is being done by a pet ambulance carrier they should be instructed to provide this "high flow oxygen" into the box. Obviously those that are NOT CONSCIOUS require at least mouth to nose ventilation, or bag-valve-mask ventilation with near 100% oxygen.
Large dogs, that are too large for small boxes should receive a sedating drug on admission..prefer ketamine and butorphanol and acepromazine in doses of 1-2 mg/kg, 0.1 mg/kg and 0.01 mg/kg respectively given in the epaxial muscles and then as they settle oxygen is switched from giving by jet-flow and canopy techniques to bag-valve-mask with a tight fitting mask.
Animals that were initially placed in the small confined box should now be given the same cocktail of ketamine, butorphanol and acepromazine. This can be done by use of the IM epaxial route OR it may be that an IV rout can be provided by using an "oxygen bag-over-the cat technique" where the patient's small box is covered with a large enough clear-plastic bag and oxygen continued to be given at high levels enough to inflate the bag covering the box. The cat is "shaken" out of the box and into the clear-plastic flexible bag filled with oxygen. This technique is recommended to be able to give the cat its epaxial ket-but-ace cocktail – injecting right through the bag. It is very important not to try and handle the cat before it is sedated adequately enough. Ketamine is a very good bronchial-dilator and is good for the asthmatic case; the butorphanol is a redistributor of lung blood volume and a lowerer of vascular resistance and blood pressure which decreases intrapulmonary hemorrhage and edema in heart failure patients, the acepromazine cancels out the systemic hypertension caused by the ketamine. Together they work very well in most cases in my experience. This combination is also a good pre-anesthesia or pre-muscle blocker in those cases that will require rapid-sequence-induction and intubation to gain tracheal – airway control to allow for positive pressure ventilation, which many severe lung disease or injury cases will require.
If the animal is not responsive to supplemental oxygen is a very positive way with a very visible decrease in the patient's "work of breathing" then bag-valve-mask ventilation should be started and a PEEP valve on the end of the AMBU exhalation arm should be added and set for 5 cm H 2 O to start.
During that time an iv access should be gotten and other added medications considered to be given. These include further medication to calm the patient if needed, furosemide for cardiac and centroneurogenic induced pulmonary edema at 4-8 mg/kg body weight, mannitol for oxygen radical scavenging at a dose of 200 mg/kg body weight given very slowly, consider the use of methylprednisolone sodium succinate for the inflammatory component of pulmonary injury, at a dose of 2-4 mg/kg body weight. Note this is a very small dose compared to those used in the past which caused significant immune system compromise; and controversial but in my experience helpful in cases of aspiration pneumonia, severe lung hemorrhage and contusion and in suspected pneumonia, the delivery of a broad-spectrum bactericidal antibiotic such as a first generation cephalosporin, giving the first dose at double the regular dose to gain a tissue level rapidly. However, in these cases I recommend getting a culture of deep bronchus secretions and Gram's stain just before giving and tailoring subsequent iv doses with the finding on the Gram's stain and cytology. The sample collection is generally gotten before the iv antibiotics are given but the antibiotics not delayed past that time.