Respiratory distress

23 Respiratory distress

Dogs and cats with respiratory distress are a relatively common presentation to emergency clinics. These patients are often extremely unstable and a rational approach to their management can make the difference between life and death in the initial period following presentation. This is especially true of cats and the bulk of this chapter will therefore focus on this species. However, many of the principles discussed are equally applicable to dogs, about which some information is provided at the end.

Approach to Feline Respiratory Distress

Respiratory distress can occur as a result of an abnormality affecting any one or more of the following areas:

• Upper respiratory tract (URT) (e.g. laryngeal neoplasia)

• Lower respiratory tract (e.g. feline bronchial disease)

• Lung parenchyma (e.g. pulmonary contusions, pulmonary oedema)

• Pleural space (e.g. pleural effusion, pneumothorax)

• Thoracic wall and diaphragm (e.g. traumatic diaphragmatic rupture).

Being able to identify the area affected is extremely important with respect to patient management.

Clinical Tip

• Abnormal respiratory behaviour can also occur as a result of changes affecting other systems, in particular the central nervous system and alterations in acid–base physiology.

Signalment, history

It is often possible to make sensible judgements as to the most likely causes of a cat’s respiratory distress on the basis of its signalment and a very brief history. For example:

• A 1-year-old male domestic short hair with no significant preceding history returns home with difficulty breathing, pelvic limb lameness and blood on the face. The most likely cause of this cat’s respiratory distress is traumatic injury resulting in pneumothorax and/or pulmonary contusions (haemothorax and diaphragmatic rupture also possible).

• A 4-year-old female neutered Abyssinian with no outdoor access is found with severe difficulty breathing on the owner’s bed, where she has been all evening. The most likely causes of this cat’s respiratory distress are feline bronchial disease and pleural effusion due to neoplasia or heart disease. The owner goes on to report that the cat has had intermittent self-limiting episodes of coughing over the preceding 3 months. This extra information makes feline bronchial disease the most likely diagnosis.

Following presentation

Clinical Tip

• A cat with respiratory distress is likely to be at its most unstable on presentation. The stress of being in the carrier, of travelling and of a strange environment is much more significant in a cat with potentially life-threatening respiratory embarrassment. Even gentle restraint at initial presentation can be enough to cause some cats to fully decompensate, and a hands-off approach with an initial period of oxygen therapy is most prudent.

• The degree of handling is a judgement to be made on an individual case basis but where there is any doubt at all, the reader is encouraged to adopt the principle of first doing no harm. The majority of cats with respiratory distress will benefit from a period of oxygen therapy before thorough evaluation and intervention.

• There is no rational justification for excessive manual restraint of a cat with respiratory distress.

The author’s initial approach to a cat that presents with moderate or severe respiratory distress is as follows.

Observation

The cat is first briefly observed in its carrier as much information can often be obtained from this approach (see Table 23.1).

Table 23.1 Observations and their interpretation in cats with respiratory distress

Observation	Interpretation
Mental alertness and pupil size	An anxious cat is likely to be more severely affected Marked pupil dilation can be an ominous sign indicating impending respiratory arrest and should prompt rapid intervention
Respiratory rate, effort and pattern	Observing respiratory patterns can be difficult but may yield very useful information. Reported associations include: mixed (inspiratory and expiratory) dyspnoea with a fixed upper respiratory tract obstruction (e.g. laryngeal mass); mixed dyspnoea, in particular with prolonged expiration and an expiratory push, in feline bronchial disease Increased abdominal effort may be seen Paradoxical abdominal movement (where the thorax and abdomen move in opposite directions) may occur with severe dyspnoea
Mucous membranes	Unless severe, pallor of mucous membranes may be difficult to identify from afar Cyanosis is indicative of severely compromised oxygenation and should prompt rapid intervention An animal with pink mucous membranes may still be severely hypoxaemic and the clinician should not be lulled into a false sense of security
Position and posture	Cats in respiratory distress will usually sit in sternal recumbency or show orthopnoea Lateral recumbency is often an ominous sign indicating impending respiratory arrest and should prompt rapid intervention Neck extension and open mouth breathing may be seen
External evidence of trauma	Raises the index of suspicion for common traumatic causes of respiratory distress (e.g. pulmonary contusions, pneumothorax)

Brief examination

An extremely brief examination is then performed. This is done with the cat in its carrier, if that is the cat’s preferred option and the carrier design allows. Otherwise, it is done in close proximity to a prepared oxygen cage and only if the cat has not been distressed in any noticeable way by removal from its carrier. Attention is paid to the following:

• Sternal cardiac auscultation:

– Is the heart rate subjectively fast or slow? Is there a gallop sound or a murmur? (Bradycardia in a cat with respiratory distress may be an ominous finding; marked tachycardia with a gallop sound or murmur may point to a cardiogenic cause but it is noteworthy that the lack of a murmur or a gallop sound does not rule out heart disease.)

– Are the heart sounds muffled?

– Are the heart sounds in a normal position?

Tags: Saunders Solutions in Veterinary Practice Small Animal Emergency

Sep 3, 2016 | Posted by admin in SMALL ANIMAL | Comments Off

Full access? Get Clinical Tree

Get Clinical Tree app for offline access

Get Clinical Tree app for offline access