Our criticalist, Katie Nash, BVSc, MS, DACVECC, discusses frequent topics of interest from the referring community.

• Approach to the cat in respiratory distress
• Management of severe anaphylaxis
• Cardiopulmonary resuscitation basics
• How to contact me

Approach to the cat in respiratory distress

Cats are notorious for hiding signs of illness until it is very advanced. The feline respiratory distress patient is truly fragile and at risk of further decompensation and sudden death even from the stress of a general physical examination. Any cat displaying signs of true distress, such as open-mouthed breathing or orthopnea with abducted elbows and extended neck, is at real risk. Cyanosis and paradoxical abdominal effort are late changes only seen with impending respiratory failure and the absence of these do not indicate patient stability. While thoracic auscultation, thoracic radiographs, and blood tests such as feline proBNP snap tests may all be helpful diagnostics, these should not be performed immediately in an unstable patient as the stress of handling can be lethal. Likewise, avoid stressful procedures that require restraint such as IV catheter placement in the initial crisis.

It is helpful to take the time to examine the patient from a distance as the respiratory pattern can help localize the problem. Cats with a prolonged inspiratory phase of respiration often have extrathoracic disease, such as laryngeal or cervical tracheal obstruction, while a prolonged expiratory phase often indicates lower airway or cardiac disease. A restrictive pattern suggests chest wall or pleural space abnormalities.

Regardless of the cause of respiratory dysfunction, an initial hands-off approach is helpful. A cardiovascularly sparing mild sedative such as butorphanol at 0.1mg/kg IM (ideally via epaxial injection for the most rapid effect), oxygen therapy via an oxygen cage, and attempts to reduce stress by minimizing noise and handling may all be life-saving interventions and often allow these patients to settle enough to more safely gather additional diagnostics. The same strategies are also helpful prior to transport to a 24-hour facility.

Careful auscultation is the most helpful and least stressful initial test. Decreased lung sounds in the distressed patient should prompt immediate thoracocentesis (ultrasound-guided if available, blind if not). If a murmur or gallop rhythm is heard, 2mg/kg furosemide IM is generally safe prior to more stressful diagnostics such as thoracic radiographs. Perspex boxes can be used to keep a patient in place for a single DV radiograph. We recommend against gassing down these patients with inhalant anesthetics. Not only are unscavenged waste anesthetic gases a risk to yourself and staff, it is very stressful for the patient and will cause myocardial depression and peripheral vasodilation – a dangerous combination in a compromised patient.

Management of severe anaphylaxis

Signs of anaphylaxis exist on a continuum, with some evidence of positive correlation between rapidity of onset and severity. In dogs, the liver, gastrointestinal tract, and skin are primarily affected. Signs of severe anaphylaxis include cardiovascular collapse, vomiting, and hemorrhagic diarrhea with or without obvious dermal signs such as facial angioedema or urticaria. In cats, respiratory and gastrointestinal signs predominate. Respiratory distress from laryngeal and pharyngeal edema, bronchoconstriction and excessive mucus production is typically the first sign in cats and may be confused with severe asthma.

In severe anaphylaxis, epinephrine is the mainstay of therapy. Recommendations include giving epinephrine 0.01mg/kg IM immediately, and repeating in 5-15 minutes if needed. If the patient is in shock I recommend starting instead with an epinephrine CRI at 0.05µg/kg/min IV. Other supportive therapies include oxygen therapy, judicious intravenous fluid therapy, antihistamines such as diphenhydramine at 1-4mg/kg IM in dogs or 0.2-2mg/kg IM in cats, bronchodilators such as inhaled albuterol or aminophylline 5mg/kg slow IV in cats, and steroids such as dexamethasone sodium phosphate at no more than 0.14mg/kg IV once in both species.

Cardiopulmonary resuscitation basics

While television programs like Grey’s Anatomy show CPR survival rates approaching 50%, the reality for our patients is sadly less rosy. Veterinary data shows 7% survival to discharge for cats and only 5.6% survival to discharge for dogs for all cause arrest. Anesthetic-related arrests have a much better prognosis overall, with between 40% and 50% survival in both species.

Regardless of cause, preparedness is key and a well-stocked crash cart and regular staff training are strongly recommended. Staff should be trained to recognize signs of impending arrest, such as slowing heart rate, collapse, and irregular breathing patterns. CPR should be started immediately on any unresponsive patient with apnea or an irregular, ineffective breathing pattern. Any delay between arrest and the start of chest compressions will vastly impact chance of survival.

Focus should be on rapid recognition and immediate institution of chest compressions, with intubation, breathing, and emergency drugs being important but secondary. The ACVECC RECOVER initiative is a workgroup that describes best practice in veterinary CPR, with guidelines freely available at acvecc-recover.org. Cognitive aids such as drug dosing charts and basic and advanced life support algorithms are also available. I am happy to review current CPR guidelines with your staff, and am available for both didactic sessions and hands-on demonstrations.

How to contact me

I am always happy to review and discuss all aspects of your cases, regardless of whether you are transferring them or not. I can also help you discuss initial management, prognosis, and expected initial costs in the event that you do wish to transfer a case. I am available Wednesday-Friday and some Tuesdays and Saturdays here at VETMED (please call and ask for me directly).

To learn more about Dr. Nash, our other doctors, services, upcoming events, or to schedule a Lunch & Learn or Meet & Greet, please contact our referral relationship manager, Karin Larrick at klarrick@vetmedaz.com.