Knowing the nature of the problem, along with the signalment of the animal, allows a great deal of preparation to occur prior to the patient’s arrival (see Figure 1.2); this can save valuable time when initiating stabilisation. For example, equipment for supplementing oxygen or obtaining vascular access can be prepared, or advice can be sought regarding toxic levels, appropriate management and antidotes in cases of intoxication.
On arrival at the clinic the major body systems are assessed during the triage, and a brief ‘capsular’ history obtained from the owner (see Table 1.2). See website documents: Triage assessment sheet.
During assessment, any abnormality detected with a major body system is likely to be life-threatening; therefore measures are immediately taken to start stabilising that condition, prior to completing the rest of the examination. The aim is not to reach a definitive diagnosis, but to start treatment of life-threatening conditions. So, for example, if an animal is immediately noted to be in respiratory distress, oxygen is administered before any other part of the examination is carried out.
A useful path to follow in the initial assessment of major body systems is ABCD, where:
A and B: Respiratory System
Emergencies involving the respiratory system require rapid assessment, cautious restraint and prompt measures to start stabilisation. Assessment of the respiratory system should begin as the patient is approached by observing their posture, respiratory effort and pattern, and whether any airway sounds are clearly audible.
In the normal patient, both cats and dogs have a respiratory rate of approximately 10–20 breaths per minute (bpm), ventilation involves very little chest movement, and the chest wall and abdomen move out and in together. Whilst open mouth breathing and panting in a dog is considered normal, the same in a cat is always considered to indicate respiratory distress and oxygen supplementation is indicated.
The respiratory system of the patient is assessed by observation, auscultation and palpation.
In a collapsed patient, assess if the airway is patent by listening for breathing, and looking in the mouth for any obstruction (blood, vomit, foreign bodies). Facial injuries or cervical bite wounds can interfere with the airway by disrupting the larynx or trachea.
The patient should be closely observed before moving on to auscultation with a stethoscope. Often, observation alone is enough to determine a respiratory problem exists and dictate the animal should be moved to the treatment area to start stabilisation. Observation should focus on:
- Respiratory rate: an increased respiratory rate is termed tachypnoea. If a patient is judged to be tachypnoeic, the focus should then move to whether there is increased respiratory effort. If there appears to be no increased effort, the tachypnoea may be caused by fear, stress, pyrexia or pain.
- Respiratory effort: animals with increased respiratory effort will often alter their body posture to assist them in their efforts to ventilate adequately. The typical picture is of flared nostrils, extended neck and abducted elbows as the animal struggles to draw air in. There will often also be exaggerated chest wall movement and abdominal effort, where the muscles of the abdominal wall are brought into play to assist with breathing. In severe respiratory effort there maybe ‘paradoxical’ movement of the abdominal wall; where the abdomen moves inwards on inspiration.
- Respiratory pattern: in the normal breathing cycle, the time taken for inspiration is similar in length to expiration. Where alterations in this ratio occur it may give clues to the level of the respiratory tract at which a problem is present (see Chapter 9).
- Symmetrical movement of the chest wall: rib fractures, and ‘flail chest’ segments may cause asymmetrical movement of the chest wall.
Listening to the patient before using a stethoscope may reveal abnormal respiratory noises such as stertor, or stridor. Stertor refers to ‘snoring’ types of noise, often caused by vibration of excessive soft tissue in the oropharynx. While this is normal in some breeds of dog, in other patients it may be a sign of inflammation. Stridor is a high-pitched whistling sound, usually associated with air moving rapidly through a narrowed opening.
Auscultation in association with a respiratory pattern is vital in helping to localise the region of the respiratory tract affected (see Chapter 9).
A stethoscope should then be used to ausculate the chest wall, comparing identical areas on the left side of the chest to the right side, and similarly comparing ventral lung fields to dorsal. This comparison allows abnormalities to be more easily detected. Breath sounds may be reduced or absent where pleural disease exists (pneumothorax, pleural effusion, diaphragm rupture), or increased sounds where airway disease is present. The presence of wheezes suggests airway narrowing, and ‘crackles’ suggest the presence of fluid in alveoli.
Gentle palpation of the chest wall may be useful for detecting obvious trauma or subcutaneous emphysema. Subcutaneous emphysema is a build up of air below the skin, and can be associated chest wall defects or tracheal trauma (see Figure 1.4).