Episode 4: Dyspnoea, the first five minutes

I recently asked what sort of cases people found most intimidating. Respiratory disease was at the top of the list. Continuing with our theme of lung related topics, we are going to dive into episode two of our foundations series: approach to the patient in respiratory distress. If you are new to small animal emergency practice, either because you are moving out of general practice or transitioning from large animal medicine, or if you wanted a refresher on the basics, then this series is made for you. If you are looking for a more in-depth discussion about respiratory disease then I would suggest you listen to episode three of the podcast. 

I agree that treating respiratory distress can be a scary experience for both the medical team and the patient. The first part of our job is minimizing patient panic while trying to assess them as best we can. What patients in respiratory distress do NOT need is lots of handling and a full physical exam. Evaluate cats while still in their carrier, taking the top off if possible, and get a feeling for their respiratory rate and pattern – is their effort during inspiration, expiration, both? Is there any abdominal effort? Are there any abnormal respiratory sounds like wheezing, gurgling, coughing, stridor/stertor etc? 

That is the first part of what we call our primary survey or major body systems assessment – a brief assessment of the most important information needed to treat the patient in extremis. HR/RR/RE, pulse quality, MM colour/CRTA full exam and history will come later. You are now in a good position to provide your patient with flow by oxygen. You can trial with a mask, but most patients will not tolerate one close to their face. While that is going, you can attempt to gather a heart rate, look at the mucous membranes, and auscultate the chest. It’s important not to push the patient at this point – if they are getting stressed then back off. If you have access to ultrasound then this would also be a good time to do a TFAST/VetBLUE assessment (explain what this is). YOU DO NOT NEED X-RAYS. Quite simply you are aiming to find out if the disease is in the lungs, around the lungs (pleural space), cardiogenic, or outside of the thorax.

Now whether you decide to take a rectal temperature or not depends on the patient. We know that patients with cardiac disease (think CHF, pericardial effusion, etc) will be hypothermic due to poor perfusion to their periphery. Finding a patient both in respiratory distress and hypothermic adds suspicion to a primary cardiac cause. It is not worth restraining your patient if they are resentful of this as they can be incredibly fragile and decompensate rapidly. Tony Johnson, a criticalist from VIN, talks about a point system for cats. The closer you get to five points the higher your risk of arrest. You get 1 point for getting into the carrier, 1 point for the car ride, 1 point for a physical exam, 1 point for an IV, etc – you get the picture. What I want to reinforce is that minimal handling is the safest approach for these patients. 

Now that you have done a primary survey you need to decide if your patient can stay conscious or if you need to take control of their airway. If you have a brachycephalic, a suspect laryngeal paralysis or other type of upper airway obstruction, or if your patient looks like they are exhausted and about to go into respiratory arrest, rapid induction and intubation may be necessary. You can use propofol to effect, or a combination of ketamine and diazepam/midazolam, but propofol is likely to be fastest. However, if you make the decision to intubate a patient you need to have an exit strategy – for a patient with hyperthermia you may want to keep them intubated until their temperature has come down. For an exhausted patient, you may need to manually ventilate them and get them to definitive care elsewhere. Either way, be sure you get informed consent from the owner.

If you do not feel they need to be intubated, then now is the time to give some sedation or analgesia. Respiratory disease is scary – there is nothing more primal and fear inducing than not being able to breathe properly. This fear can exacerbate your patient’s respiratory distress, so providing some sedation can help bring them away from the edge without compromising their ability to breathe significantly. My personal choice is butorphanol +/- midazolam given intramuscularly. I don’t typically place an IV right away unless I really feel the patient will tolerate it. If you have a high suspicion of congestive heart failure (small dog with a heart murmur, hypothermic cat with crackles, etc) then you can give furosemide IM at this time, but not in the same syringe. I typically start with 4-6 mg/kg furosemide in dogs and 2 mg/kg in cats. This dose may be higher than you are used to in dogs, but it has been recommended by a number of cardiologists. You can always start lower and titrate up.

After providing sedation, provide some eye lubrication and place them in an oxygen rich environment. How you do this depends on your setup. There are several different oxygen cages/tents/etc available. Commercial oxygen cages are ideal because you can manage CO2, humidity, O2 concentration etc, but most practices will not have them. If you are using an oxygen cage or tent then you need to be very mindful of the temperature and CO2 concentration as they can both build rapidly. If you leave your patient in a sealed or very poorly ventilated system then they can become hyperthermic and hypercapneic quickly, both of which will negatively affect them. You can purchase CO2/O2/Temperature monitors and should have one if you are using these systems. 

What I do want you to remember is that oxygen can make you feel better but not necessarily fix the patient. If they have a pneumothorax, pleural effusion, pericardial effusion, a diaphragmatic rupture, etc, then they will not get better until that problem is fixed. Do not put them in oxygen and forget about them or they can die. Your physical exam should tell you if there are dull lung sounds dorsally or ventrally, but normal lung sounds does not necessarily rule out a pneumothorax or pleural effusion. With all of that in mind, this is a good time to get a full history from the owner, discuss a plan and prognosis and estimate, etc. 

Once your patient has had an opportunity to calm down in oxygen you can then start working towards a more definitive diagnosis and treatment. This may involve radiographs, blood tests, ultrasound/echo, thoracocentesis (and remember that this can be a diagnostic too), pericardiocentesis, or other tests. Get familiar with the most common primary causes of respiratory distress, including CHF, pneumothorax, pleural effusion, pericardial effusion (vomiting), pulmonary hypertension (ultrasound/lungworm), PTE, upper airway obstruction, collapsing trachea, pneumonia. Do not neglect your non-respiratory/secondary lookalikes! Pain, trauma, acidosis/acidaemia, anaemia/O2 carrying issues, hyperthermia, abdominal contents pressing on diaphragm, Pickwickian syndrome, drugs, neurological disease, metabolic derangements, etc. Be thorough, be flexible, and don’t get tunnel vision.