Critical care triage (Proceedings)

The triage examination is the initial and brief examination that occurs in the first few minutes after a patient presents to the emergency room. The triage examination is crucial to assessing a patient and determining if life-threatening problems are present. Point-of-care testing is a term used to refer to immediate testing in an emergency room. This allows the veterinarian and technician to obtain immediate results in order to rule in or out life-threatening problems. There are limitations with point-of-care testing regarding quality control; however they adequately serve their purpose regarding diagnosis of life-threatening emergencies. Frequent triage examinations, testing, and monitoring of emergent and dynamic patients is necessary to be proactive in treatment of critical patients.

The triage examination

Veterinarians and technicians have to be information gatherers in order to put the pieces of the puzzle together regarding emergency patients. One of the first pieces of the puzzle is the information gathered from the initial physical examination, or triage examination. The most basic systems that should be assessed during the triage examination are the respiratory system, cardiovascular system, neurologic system, and abdomen (GI and urogenital systems). Assessment of these systems will prompt further treatment if the animal is in respiratory distress, shock, has neurological impairment, or has evidence of an acute abdomen. Quick, accurate physical examination skills are critical skills to master as an emergency veterinarian or technician, since treatment is frequently instituted prior to obtaining diagnostics in the emergency room. The classic example of this is the animal that is in shock. Shock can be assessed and determined on initial triage examination and the decision to start fluid therapy is usually instituted prior to obtaining any other diagnostic results.

The triage exam for any animal should consist of mucous membrane color, capillary refill time, body posture, respiratory pattern, auscultation of the lung fields and heart, pulse quality, heart rate, abdominal palpation, mental status, pupillary light reflexes, and temperature. This examination will help to differentiate which major body system is causing the problem. The triage examination is ultimately followed up by a complete physical examination, subsequent repeat triage examinations, diagnostic tests, and monitoring throughout the hospitalization period. The following is a guide to how each of the above triage examination contributors can help target the cause of the problem:

Mucous membrane color:

     • Cyanosis. Cyanosis indicates severe hypoxemia. By definition, cyanosis means greater than 5 g/dL of hemoglobin is desaturated, which correlates to an oxygen saturation (SaO2) of about 75% and a partial pressure of oxygen (PaO2) of approximately 40 mmHg. Hypoxemia to this degree is life-threatening. Therefore, if cyanosis is present, it indicates severe hypoxemia and oxygen therapy needs to be instituted immediately!

     • White/pale. White or pale mucous membranes typically indicate vasoconstriction or anemia. Both of these conditions may lead to decreased oxygen delivery to the tissues.

          – Vasoconstriction is usually a result of hypovolemic or cardiogenic shock. Vasoconstriction is technically caused by release of norepinephrine and subsequent stimulation of the peripheral alpha receptors, leading to vasoconstriction.

          – Animals that have pale or white mucous membranes secondary to anemia can present differently depending on if it is acute or chronic anemia. Acute anemia (i.e. hemorrhage) will typically cause hypovolemic shock (tachycardia, tachypnea, hypotension, dull mentation, etc.). Chronic anemia patients (e.g. cats with FeLV) usually tolerate their anemia very well. They may be slightly tachycardic, tachypneic, or weak, but won't usually be hypotensive or in shock.

     • Grey/muddy. Grey or muddy mucous membranes usually indicate poor tissue perfusion and tissue hypoxia. Shock or hypoxemia should come to mind in patients with grey or muddy mucous membranes.

     • Brown. Brown mucous membranes may indicate methemoglobinemia, which decreases the oxygen carrying capacity of hemoglobin, leading to decreased O2 delivery. The most common cause of methemoglobinemia in veterinary medicine is Tylenol toxicosis in cats.

     • Bright red/injected. Bright red mucous membranes may indicate decreased cellular utilization of oxygen (seen with cyanide poisoning or sepsis), decreased oxygen-hemoglobin binding (seen with carbon monoxide poisoning), or vasodilation (frequently seen with sepsis or heat-stroke).

     • Petechia/Ecchymoses. May indicate a coagulation abnormality, especially a platelet disorder.

Capillary refill time

     • Capillary refill time is an assessment of capillary perfusion. If you blanch the mucous membranes and they refill very slowly, this indicates that the pre-capillary arteriolar tone is very high (as seen with norepinephrine release and vasoconstriction). If the mucous membranes refill very quickly after blanching, it indicates that pre-capillary arteriolar tone is very low (i.e. as seen with vasodilation).

     • Quick capillary refill times (i.e. <1 sec) indicates vasodilation or a hyperdynamic state. A fast CRT should raise a red flag that a patient may be septic or in septic (distributive) shock. However, patients that have recently exercised, have heat stroke, or have evidence of the systemic inflammatory response syndrome (SIRS) also frequently have a fast CRT.

     • Slow capillary refill times (i.e. >2.5 sec) indicate vasoconstriction or low cardiac output (seen frequently with hypovolemic, traumatic, or cardiogenic shock).

Respiratory patterns

     • Much can be gained from proper assessment of the respiratory system. Simply observing an animal's respiratory pattern (even prior to auscultation) can lead to tremendous insight into the cause of the breathing pattern. In fact, this part of the examination can be done as you approach the animal during triage.

     • Upper airway disease or obstruction usually presents with increased airway noise on inspiration (stridor), increased inspiratory time, and increased inspiratory effort.

     • Lower airway disease commonly has an increased expiratory effort with an "abdominal push".

     • Severe lower airway disease, combination upper and lower airway disease, metabolic disease, and neurologic disease may have both increased inspiratory and expiratory effort.

     • Eupnea is the term used to describe a normal breathing rate and pattern.

     • Dyspnea is the term frequently used to describe an animal in respiratory distress. However, some clinicians prefer the term "respiratory distress" over dyspnea. This is because in people, the term dyspnea is associated with the feeling/emotion of respiratory distress versus the actual pattern.

     • Tachypnea is an abnormally fast respiratory rate and is commonly seen with many lower airway disorders, pain, pleural space disease, and metabolic acidosis.

     • Bradypnea is an abnormally slow respiratory rate and is commonly seen with central neurological disorders or drug induced respiratory depression.

     • Coughing may be present with upper or lower airway disease. Productive versus non-productive coughing may help localize from where the cough is originating.

     • A Kussmaul breathing pattern consists of deep, rapid breathing that is commonly associated with metabolic acidosis.

     • Biot's respiration pattern consists of deep, constant rate breathing interspersed with periods of abrupt apnea, usually seen with elevated intracranial pressure.

     • Cheyne-Stokes respiration is a pattern of gradually increasing respiratory rate followed by gradually decreasing respiratory rate, ending in periods of apnea. This pattern is commonly seen with coma and disruption of the medullary breathing control centers in the brain.

     • An ataxic breathing pattern is one that is very erratic and has no particular pattern. Ataxic breathing is usually associated with brainstem lesions.

     • An apneustic breathing pattern is a "breath holding" pattern seen after inspiration and commonly is seen with brain stem disease.

     • Agonal breathing consists of gasps, followed by periods of apnea, followed by more gasps and indicates severe brain stem hypoxia and near death.

Body posture

     • Body posture/position can help the veterinarian determine the seriousness of a problem.

     • Animals in respiratory distress commonly present with an orthopneic posture, which consists of an extended head/neck and standing with elbows abducted in order to expand their chest cavity.

     • Animals in shock are commonly laterally recumbent and have decreased mentation.

     • Animals with neurologic disease may be ataxic, comatose, stuporous, obtunded, or seizuring.

     • Animals with an acute abdomen may have a hunched posture or sit in a "praying" position.

Auscultation

     • Pulmonary auscultation should be performed in all lung fields. Thorough lung auscultation will help define respiratory disease even more specifically, especially when used in conjunction with breathing pattern. Auscultation over the trachea should also be performed to determine if abnormal lung sounds are due to referred upper airway noises.

          – Fine crackles: Associated with opening and closing of collapsing alveoli, usually due to fluid in the alveoli (commonly seen with pulmonary edema, pulmonary contusions, and pneumonia).

          – Course crackles: Indicates large airway disease or pulmonary fibrosis.

          – Increased bronchial or bronchiolar sounds: Indicates increased movement through the large airways. May be normal in a panting dog, or may indicate bronchial/bronchiolar or interstitial disease. Some people refer to these lung sounds as being "harsh".

          – Dull lung sounds: Commonly associated with pleural space disease. Distribution of dull sounds may help differentiate inciting cause of pleural space disease. Dull lung sounds dorsally commonly indicate pneumothorax, potentially a diaphragmatic hernia, or a space occupying mass. Dull lung sounds ventrally commonly indicated fluid accumulation, a space occupying mass, or a diaphragmatic hernia.

          – Pleural friction rubs: Associated with pleural fibrosis or pleuritis.

          – Wheezes: A squeaking or whistling noise associated with air movement through a narrowed opening. Commonly heard with narrowed tracheobronchial airways in asthma or during tracheal obstruction.

     • Cardiac auscultation should be performed on both the right and left side of the heart. Determining heart rate, rhythm, the presence of murmurs, and the presence of muffled heart sounds, in conjunction with simultaneous palpation of pulses will give tremendous insight into a patient's status.

          – Arrhythmias: May be present with primary cardiac disease or extra-cardiac disease. An ECG and electrolyte analysis is useful in determining the type and potential cause of arrhythmia. Tachycardia is frequently associated with shock and should be recognized as a problem. Severe bradycardia may be associated with life-threatening disorders such as hyperkalemia or complete AV block.

          – Murmurs: An indication of turbulent blood flow. Commonly associated with regurgitant disease, stenosis, changes in blood viscosity, or congenital abnormalities. Murmurs may be difficult to hear if pleural effusion is present or lung sounds are excessively loud, so don't completely rule out a murmur until a more thorough auscultation can be performed. In addition, loud lung sounds may be mistaken for heart murmurs.

          – Muffled heart sounds: may indicate pericardial effusion, pleural effusion, or a space occupying mass in the thorax.

Pulse quality

     • Pulse quality is technically an assessment of pulse pressure (i.e. the difference between systolic and diastolic pressure). The "fullness" of the artery helps indicate the intravascular volume status.

     • A low pulse quality or absent pulse typically indicates the presence of hypotension. A normal pulse quality does not necessarily rule out hypotension. Severe vasoconstriction may decrease pulse quality.

     • Simultaneous heart auscultation and palpation of pulses should be performed to determine if pulse deficits are occurring.

Abdomen

     • A quick abdominal palpation is necessary to determine if abdominal pain or distension is present. The presence of abdominal pain is abnormal and should always be evaluated more thoroughly. Abdominal distension may indicate the presence of organomegaly, abdominal effusion, or abdominal neoplasia and should be evaluated thoroughly prior to dismissing it as a potential problem. In addition, some animals with severe diaphragmatic hernias may have evidence of "an empty" feeling abdomen.

Neurologic evaluation

     • The mental status of the patient is necessary to help determine if there is a neurologic component to the disease process. Animals with head trauma may be mentally dull, have evidence of pupil size abnormalities or disparities, or have evidence of external trauma to the head. This is important to recognize, as head trauma patients may need to be resuscitated differently than other types of shock patients.

     • Seizuring patients should have an IV catheter placed and an anticonvulsant available in case seizure activity begins again. The temperature should be evaluated, as seizuring patients are frequently hyperthermic.

     • Proper neurological assessment is also necessary for animals that come in paraparetic or tetraparetic, which will aid in prognosis to the client.

     • It is important to note that many patients in shock have decreased mental awareness. Therefore, a neurologic assessment should be done repeatedly until the animal is no longer in shock, in order to get an accurate neurologic assessment.

Temperature

     • Obtaining a temperature can be stressful and should not be performed initially if it makes the patient with respiratory compromise struggle. Temperature is most important in animals with upper airway obstruction, in patients after a seizure episode, heat stroke patients, and potential septic patients, since these situations commonly lead to severe and life-threatening hyperthermia or fever. Hypothermia is commonly associated with shock, especially in cats, and should be assessed.

Conclusions

The initial physical examination that is performed on an emergency patient is extremely helpful in diagnosing life-threatening problems. Point-of-care monitoring us frequently necessary in conjunction with the triage exam in order to get a more complete picture of the patient's status.