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Principles on which approach is predicated:
1. Risk-benefit assessment:
Help as much as possible, harm as little as possible
Dyspnoeic cats can be very vulnerable, easy to ‘tip over the cliff edge’
“sometimes cats are just going to do the dance of death and there is only one outcome…BUT the premise is that for a significant proportion of the dyspnoeic cats that we see there is real benefit in a rational approach to their management.”
2. Emergency Medicine philosophy:
ALSO SEE THIS BLOG POST.
- Identify and address potentially life-threatening problems
- Make the patient feel better
Do not necessarily have to answer all the questions about what is going on with the patient early on
A slow staged approach is essential
Medical therapy or interventions may need to be provided empirically or presumptively
Judicious pattern-spotting may be appropriate
3. Individual patient approach:
Start with a rational cautious general approach, modify and pivot according to individual patient
Some dyspnoeic cats are very amenable and easy to do things to, especially with a minimal restraint hands-off approach; others require a much slower staged approach
4. Clinical confidence, reasoning and gestalt:
Approach described relies to some extent on clinician confidence in terms of examining the patient, interpreting findings, and drawing rational conclusions with all the available information.
5. Anatomical localisation:
Where in this patient’s respiratory tract do I think the cause is?
Five anatomical sites:
- The upper respiratory tract including the proximal trachea
- The lower respiratory tract including the distal trachea, bronchi and bronchioles
- The lung parenchyma
- The pleural space
- The chest wall and diaphragm
Localisation helps to consider differential diagnoses
Multiple sites may be affected
Respiratory status can be affected by e.g. pain, raised temperature, acid-base status; typically would not cause dyspnoea, more often tachypnoea
Essential not just for dyspnoeic cats but all emergency patients!
Ideally clinic in a constant state of preparedness
When awaiting a dyspnoeic cat (if you know they are en route!) ensure that:
- All potential team members that will be involved are informed
- You know how you are going to be providing oxygen supplementation
- Potentially indicated drugs and dose rates are to hand
- You get thoracocentesis equipment together
2. Initial period after arrival:
“When the cat arrives at the clinic he or she could potentially be at their most vulnerable depending on how well they have coped with being in the carrier and travelling.”
Triage starts immediately with observation:
- Respiratory status: effort, postural adaptations, pattern, subjective rate
- External evidence of trauma
- Some perfusion information (e.g. if the cat is sitting upright they must have some level of adequate perfusion even if not normal)
Initial period of oxygenation:
Typically hands-off in oxygen cage
In carrier with top removed or after careful removal from carrier (no time to be tipping cat out of carrier from height!)
E.g. 15-20 minutes but no prescribed period
- Cat time to calm down after journey: improves welfare and potentially reduces oxygen consumption
- Improved oxygenation if compromised
Potential benefit of oxygen cage depends on individual patient:
Degree of improved oxygenation affected by existing pathology
Potentially greater benefit with pulmonary parenchymal disease (e.g. contusions, oedema) but less with pleural space disease (e.g. effusion, pneumothorax) if lungs too compressed
All cases may benefit from period of hands-off observation after stress of journey
DO NOT SCRUFF CATS IN GENERAL AND ESPECIALLY NOT DYSPNOEIC ONES – PLEASE!
Scruffing is rarely necessary and anecdotally used excessively
Before putting cat in oxygen cage; or potentially after some time in oxygen cage
Flow-by oxygen supplementation – if tolerated
- Sternal cardiac auscultation: murmur? Gallop sound? Other rhythm disturbance? Subjective heart rate? Muffling? Displacement?
- +/- Concurrent pulse palpation
- Mucous membranes
- Lung auscultation: dullness – ventral, dorsal, diffuse? Louder sounds – harshness, crackles, wheezes? Bilaterally symmetrical?
- Upper respiratory tract dyspnoea?
On-going observation – can be continued more extensively once in oxygen cage
“Beyond just deciding whether lung sounds are louder or quieter than normal, it is important to consider whether the loudness of the lung sounds is appropriate for the patient’s respiratory rate and effort? Apparently normal lung sounds in a cat with marked respiratory effort may in fact be inappropriately quiet, suggesting for example pleural effusion or severe consolidation.”
How long you spend doing this brief examination – if you do it at all – needs to be tailored to the individual cat.
3. Client communication:
Can use oxygenation period to consult with clients, get further consent
May already have reasonable idea of what is wrong with the cat, if not specific disease(s) then anatomical localisation and potential differentials, based on:
- Any known history
- Brief examination
**Ensure cat observed by team member throughout**
Potential next steps…
4. Diagnostic Imaging:
As mentioned previously, anatomical localisation is essential in dyspnoeic patients
May have already achieved this; if not what else can be done to localise better and potentially establish specific diagnosis?
“A lot of people are very keen to radiograph dyspnoeic patients very quickly in order to try and get the information that they feel they need to be able to help the patient. And my premise is that I think in many cases it is possible to do this without needing to take radiographs early on.”
Radiographs typically provide useful information but at what risk to the patient?
THINK RISK-BENEFIT, RISK-BENEFIT, RISK-BENEFIT!
Can you delay radiography, do more to improve stability and reduce risk first?
Take steps to mitigate risk if radiography performed – prepare everything ahead of moving cat, quiet environment, ‘cat in carrier’ technique etc.
Point-of-care ultrasound (POCUS):
Getting increasing attention in human and veterinary medicine; increasing good quality clinical data in humans
Not just thoracic focused assessment with sonography for trauma (T-FAST) but for other causes of dyspnoea too
Non-invasive, minimal patient restraint
Potentially leaving cat in oxygen cage
Clipping vs. non-clipping?
Use quiet patient-friendly clippers
“what we are after with POCUS, especially in dyspnoeic cats, is to get the interpretable images that we need in the most efficient time possible and sometimes trying to do this in the cage or with no clipping is not going to get you this result. So there is a balance to be found between handling and intervening with the patient and giving yourself the best and most efficient chance of success.”
Everyone, with just a little training and practice, can identify pleural effusion
With more training and practice, may be able to evaluate left atrial size, cardiac contractility, lung parenchyma, pneumothorax
BUT start with reasonable expectations and then improve in time
5. What else?
Early IV access allows less invasive drug therapy; important if cat rapidly decompensates
But…THINK RISK-BENEFIT, RISK-BENEFIT, RISK-BENEFIT!
What can you do to make the cat more stable before catheterisation to reduce risk? E.g. thoracocentesis; empirical drug therapy
Clip at least two peripheral vein sites and apply topical local anaesthesia beforehand
Try to minimise environmental stress – quiet room, minimal traffic, etc.
Ask the most skilled team member to attempt catheterisation first
Empirical thoracocentesis frequently safer than radiography; do before/after POCUS according to circumstances
Diagnostic and therapeutic, potentially life-saving
Suspect pleural effusion? Target ventral third
Suspect pneumothorax? Target dorsal third
Unsure? Target midway up chest
Collective anecdotal experience suggests clinically significant iatrogenic complications of thoracocentesis are rare
Minimise risks and maximise chance of successful outcome by preparing equipment in advance, tailoring manual restraint to individual patient
Consider e.g. 0.1 mg/kg methadone (or more according to analgesia requirement) or butorphanol IV/IM beforehand: anxiolytic; thoracocentesis not totally pain-free
Some cases require more aggressive chemical restraint, e.gm ketamine/midazolam
“if you find yourself fighting with a cat trying to perform thoracocentesis, scruffing him or her or otherwise aggressively restraining the cat, then I really do think you should take a step back and consider whether this is a rational thing to be doing, is it the safest and kindest thing for the cat, and is it likely to give you the best chance of a successful outcome. I would strongly argue that it is usually a flawed approach.”
THINK RISK-BENEFIT, RISK-BENEFIT, RISK-BENEFIT!
“When you are considering doing a blood test on a dyspnoeic cat, stop for a second and consider how the results of that test will change your current plan…ask yourself how the results of those tests will help you to help the patient in their current circumstances; do the results help you to stabilise the cat or could you postpone doing those tests for now?”
- Appreciate that dyspnoeic cats can be very vulnerable and easily tipped over the cliff edge.
- Even more so than normal, pay acute attention to the risk-benefit assessment at all times.
- Understand that each cat is clearly going to be an individual patient with their own set of circumstances and behaviour, but that a hands-off, slow, staged approach is likely to be the least risky and most beneficial in most cases.
- Continue to improve your ability and confidence in examining these cases paying attention to trying to anatomically localise the cause of the dyspnoea; this will allow you to make the most sensible decisions in terms of how to help the patient.
- Don’t be in a hurry to x-ray dyspnoeic cats until and unless you feel like you have done all you can to make them as stable as possible beforehand.
- And, lastly engage more with POCUS, point-of-care ultrasound, if you are not already.
Please do get in touch using the contact form on website, via email at firstname.lastname@example.org, via Twitter @VetEmCC or via Facebook at the Veterinary ECC Small Talk page. I would love to hear what you think of my views expressed in this episode, what you agree with and indeed what you might disagree with.
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