Common emergency presentations – the initial triage: as easy as ABC

ABSTRACT

Initial triage of all emergency presentations involves assessing the airway, breathing and circulation.

This article will look at these first three steps (A = airway; B = breathing; C = circulation) and the more common conditions that cause dysfunction in these body systems.

Emergency presentation of small animal patients can range from acute traumatic incidents to decompensation of a chronic condition. Prompt triage is vital in the management of such conditions because it allows rapid stabilisation.

This article will focus on the most common emergency situations identified during triage. These cases can be both incredibly challenging and highly rewarding for all members of the veterinary team.

In general, staff should obtain as much information about the patient’s signalment, clinical signs and history prior to them arriving – this allows the team to prepare the necessary equipment. A coordinated team approach to information gathering, while a focused examination is taking place, allows for more rapid initiation of treatment.

It is always critical to perform as much of a physical exam as reasonably possible prior to administering therapies, as this will guide treatment, monitoring and prognosis. However, analgesia should never be withheld.

Primary survey should be performed within minutes of the patient’s arrival and should be quick to do; airway, breathing and circulation are all assessed immediately. This should be followed by a more thorough investigation of the major body systems (respiratory, cardiovascular and neurological) to guide further investigation or therapeutics. Abnormalities identified at either of these two points should be addressed, and the patient stabilised, before progressing to further diagnostic procedures.

It is also worthwhile to apply this same process in any hospitalised patient when their clinical condition deteriorates while undergoing treatment.

Airway

Initial assessment

Any dyspnoeic patient should be handled carefully and efficiently to minimise oxygen consumption. Supplemental oxygen therapy can be provided while an initial physical exam is performed.

When assessing the airway, check:

Is the airway clear?
- foreign material – for example, ball or stick
- bodily fluids – for example, vomit
Are signs of upper airway obstruction present?
- increased inspiratory effort
- stridor – for example, laryngeal paralysis
  - Is this a large-breed, older dog?
- stertor – brachycephalic obstructive airway syndrome; nasopharyngeal polyps in young cats

While pattern recognition is generally discouraged, in these emergent cases it can help to direct diagnostic and therapeutic plans efficiently – particularly for localising the source of respiratory distress.

Initial management

Supplemental oxygen therapy should be instituted initially. Additionally to this, sedation can be used to ease anxiety¹.

Typically, an opioid sedative – such as butorphanol (0.2mg/kg to 0.4mg/kg) – is useful in most cases where potent analgesia is not required. Low-dose acepromazine (0.01mg/kg to 0.02mg/kg) may be required for additional sedation, as long as the circulatory system is not compromised.

In cases of imminent respiratory failure, intubation and intermittent positive pressure ventilation may be required to take control of ventilation. In cases where impending respiratory fatigue and marked respiratory distress are evident, induction of anaesthesia and intubation will often be made based on clinical judgement, as blood sampling may increase stress.

In other situations, the decision is made based on blood gas analysis: severe hypoxaemia (partial pressure of oxygen less than 60mmHg) indicating poor oxygenation despite oxygen supplementation, or severe hypercapnia (partial pressure of carbon dioxide greater than 60mmHg) indicating decreased ventilation.

An example of such a patient would be a French bulldog presenting tachypnoeic and dyspnoeic with cyanotic mucous membranes showing signs of upper airway obstruction secondary to brachycephalic obstructive airway syndrome. Such patients are incredibly fragile and require immediate sedation to decrease their anxiety and work of breathing; as well as reducing oxygen demand, reducing the work of breathing should reduce further inflammation of the upper airways.

In such patients (Figure 1), rapid intubation and securing of their airway with an endotracheal tube allows for diagnostics to be performed while allowing time for airway swelling to reduce.

Figure 1. A pug with stertor and inspiratory dyspnoea.

Tracheostomy is rarely required in an emergency and ideally approached in a sterile controlled manner, although the equipment and skills necessary to deal with “a difficult airway” should always be prepared prior to attempting intubation of these patients.

Management of hyperthermia is vital and often overlooked. Cooling measures – such as fans, spraying the patient with tepid water and IV fluids – can be easily implemented at the same time as other emergency treatments. Cold/icy water should be avoided as this may lead to vasoconstriction in the periphery and hinder the cooling process.

Typically, brachycephalic patients with severe upper respiratory tract obstruction will be hyperthermic due to impaired heat loss. Body temperature higher than 41.6°C significantly increases tissue oxygen consumption, and can lead to disseminated intravascular coagulation and multiple organ failure².

Temperature should be closely monitored and active cooling should be stopped when body temperature reaches approximately 39.4°C.

When providing oxygen therapy using a tent or cage, the humidity and temperature of these environments can rise rapidly and exacerbate respiratory distress.

Breathing

Assessing breathing

Figure 2. Orthopnoea in a bulldog. — **Figure 2.** Orthopnoea in a bulldog.

When assessing breathing:

Increased respiratory drive, be that physiological or pathological, will result in recruitment of the secondary muscles of respiration. Evidence of paradoxical or uncoordinated respiration can indicate respiratory distress.
Posture and facial expression – dyspnoeic patients will often abduct their elbows, extend their necks and breathe through an open mouth to minimise resistance to airflow.
Thoracic auscultation – examples of findings are:
- dull/quiet lung sounds:
  - “something in the way” – such as pneumothorax, pleural effusion or diaphragmatic hernia
  - collapsed lung/atelectasis – pneumonia, abscess, pulmonary neoplasia
- crackles:
  - for example, pneumonia, contusions, coagulopathy
  - fibrosis – for example, West Highland white terrier idiopathic pulmonary fibrosis (Video 1)
  - pulmonary oedema (Figure 2):
    - cardiogenic
    - non‑cardiogenic pulmonary oedema – for example, electrocution, suffocation, strangulation, acute respiratory distress syndrome
- wheezes:
  - lower airway collapse or constriction – typically causes increased expiratory effort:
    - feline lower airway disease
    - chronic bronchitis

Video 1. Idiopathic pulmonary fibrosis in a West Highland white terrier.

Initial management

Oxygen therapy should be implemented immediately; individual patient tolerance to this may vary (Table 1). Some patients will tolerate flow-by oxygen, while others will resent this technique. Such patients often require sedation, gentle handling and oxygen supplementation in an oxygen tent (Figure 3).

Investigation

Point-of-care ultrasound of the thorax (Figure 4) is a rapid, minimally invasive diagnostic tool that is gaining popularity in emergency management. It can be used to quickly identify pleural effusion, pneumothorax, fluid within the lungs (blood, water), pericardial effusion, subjective cardiac contractility and cardiac chamber enlargement.

This form of imaging has been shown to aid in differentiating cardiogenic respiratory disease from non-cardiogenic respiratory disease in most cases in cats⁴. It is also useful for this purpose in dogs, although, typically, less difficulty exists in differentiating cardiac and non-cardiac-related dyspnoea based on history and clinical exam compared to cats⁵.

Where pulmonary oedema is identified in conjunction with evidence of congestive heart failure, diuretic therapy can be started. The most commonly used first-line diuretic is furosemide, typically used at an initial dose of 2mg/kg to 4mg/kg, given as a bolus IV if possible, or IM if IV access cannot be obtained.

$Table 1. Approximate fraction of inspired oxygen (FiO2) attained with oxygen supplementation1,3$

Figure 3. Bilateral nasal oxygen catheters.

Figure 4a. Performing thoracic point‑of‑care ultrasound

Figure 4b. B lines on point‑of‑care thoracic ultrasound consistent with fluid in the peripheral lung fields.

Management

Thoracentesis (Figure 5) is one of the few procedures in emergency medicine that is both diagnostic and therapeutic.

In cases of severe pleural space disease, thoracentesis is likely to be the only way to resolve the respiratory compromise. Prior to doing this, relevant history – including access to anticoagulant rodenticides – should be obtained.

If haemothorax secondary to rodenticide toxicity or other coagulopathy is suspected, thoracentesis should only be performed if it is required to relieve respiratory distress.

Avoid removing an excessive volume, as the remaining blood in the thorax will be resorbed into circulation⁶.

Autotransfusion can be considered if significant hypovolaemic/hypoxaemic shock is evident.

Figure 5. Thoracentesis in a cat with congestive heart failure. — **Figure 5.** Thoracentesis in a cat with congestive heart failure.

A history of trauma (particularly blunt trauma to the thorax) should always raise concern for the possibility of pneumothorax. Cases of tension pneumothorax will need urgent thoracentesis.

Respiratory compromise may not be evident initially, but can develop gradually. A recent study of 364 dogs suffering thoracic trauma found a 12% prevalence of lung lacerations, with 25% of those cases developing pneumothorax⁷. Progression or development of pulmonary contusions in the initial 24-hour to 36-hour period following trauma can also lead to respiratory compromise.

In patients showing evidence of septic shock, or with evidence of bacterial involvement, prompt antimicrobial therapy is recommended.

One study comparing thoracic point‑of‑care ultrasound findings to chest radiographs in cases of respiratory disease identified that pneumonia more commonly resulted in alveolar-interstitial syndrome (AIS) in the right unilateral thorax or, less commonly, in the left cranial thorax; whereas cardiogenic AIS was typically a diffuse or a bilaterally caudal pattern⁸.

While it is important to note these patterns are not consistent across all cases, it can aid decision‑making in emergency situations or where access to advanced imaging – such as CT – is not available, or where the patient is not stable enough for procedures such as bronchoscopy and bronchoalveolar lavage.

Temperature is also helpful in differentiating non-cardiogenic and cardiogenic respiratory distress in cats. The RAPID cat study⁹ found acutely dyspnoeic cats with no signs of trauma, presenting with a rectal temperature below 37.5°C or a pulse greater than 200bpm, or a respiratory rate greater than 80 breaths per minute, were significantly more likely to be in congestive heart failure.

An example of such a case would be a 14‑year‑old cat presented tachypnoeic with shallow breaths, reduced lung sounds bilaterally on auscultation and open-mouth breathing when handled. Feline patients are particularly susceptible to stress during handling and often benefit from sedation with an opioid – such as butorphanol – to reduce anxiety, and placement in an oxygen tent as an initial step.

Figure 6. Left atrial to left aortic diameter in a dog with congestive heart failure. — **Figure 6.** Left atrial to left aortic diameter in a dog with congestive heart failure.

A point-of-care ultrasound scan can be used to confirm the presence of pleural effusion, and a left atrial to aortic diameter ratio (LA:Ao) can be used to ascertain if congestive heart failure is the underlying cause (Figure 6).

An LA:Ao greater than 1.5 is consistent with cardiac disease⁴. LA:Ao can, however, be very difficult to obtain in dyspnoeic cats⁴.

The left atrial diameter on the long‑axis right parasternal view can be used when it’s not possible to obtain a reliable LA:Ao. A left atrial diameter greater than 1.65cm in conjunction with signs of congestion – such as B lines, pleural effusion or pericardial effusion – is consistent with congestive heart failure¹⁰.