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Respiratory emergencies in the ICU (Proceedings)

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Aug 01, 2009

Respiratory emergencies should always be triaged quickly and with precision. Avoiding stress in the dyspneic patient is crucial. Oxygen cages can be useful in implementing a phase therapy approach; oxygen masks or nasal oxygen can be more effective in supplying oxygen but patient restraint alone can cause an arrest if traumatic. Minimal restraint and avoiding head and neck manipulation is therefore critical in respiratory diseases. Venipuncture, rectal temperature, and IV catheterization should not be attempted without first allowing the patient to acclimate to its surroundings and breathe more easily, if time allows.

Identifying common respiratory patterns

Developing an acute dyspnea strategy should be foremost in any emergency facility. Aquariums should be ready for the dyspneic pediatric patient, rather than large oxygen set ups, in order to provide an oxygenated environment in a shorter amount of time. Sedation, emergency tracheostomy kits, endotracheal tubes, and forceps should also be readily available if the patient is in respiratory distress or respiratory arrest due to tracheal trauma, foreign body, pulmonary constriction, severe pulmonary contusions or cardiac insufficiency. Patients in oxygen facilities should be monitored for increased body temperature, as the internal environment may become humid.

Auscultation is the single most important nursing triage tool in assessing the dyspneic patient. Proper technique for accuracy and expediency is paramount. The patient should be in sternal recumbency and allowed to inhale oxygen during the exam to facilitate lung expansion and to auscultate lung fields accurately. It is recommended to use the pediatric head of the stethoscope in smaller patients to avoid guttural sounds. The auscultation should include both sides of the chest, ventrally and dorsally, while paying close attention to the respiratory pattern. Respiratory effort should be noted in conjunction with the respiratory component. Clinical signs of respiratory insufficiency include tachypnea, cyanosis, open-mouth breathing, head and neck extension, and abnormal chest movement.

In general, respiratory patterns and lung sounds are subtler in cats than in dogs. In addition, cats have a unique ability to mask abnormal respiratory processes. In general, respiratory patterns should be assessed before restraint or manipulation when at all possible. Note that certain patterns can provide diagnostic information. For example, abdominal components can indicate pleural complications (fluid or air), neurological compromise or trauma (cervical lesions), or chest wall trauma. Paradoxical movements may indicate diaphragmatic hernia or neurological conditions. Chest expansion should be assessed in any respiratory movement, paying close attention to both inhalation and exhalation sounds during auscultation. It is important to note on which side or sides abnormal sounds are heard, and whether they are ventral or dorsal, cranial or caudal. Note that pain alone can cause an abnormal respiratory pattern and respiratory rate.

In the critically ill, it is important to note that the respiratory rate is just a number. The respiratory effort, respiratory component, and the mucous membrane color are more important than a single number. Duration of the respiratory insufficiency is also important to note. Special focus on the patient's body temperature, blood pH, and blood glucose is of particular importance if the respiratory effort is prolonged, particularly to the pediatric patient. Pulse oximetry can also be a useful tool in assessing respiratory function, but should not take place of thorough exam. Pulse oximetry measures oxygen saturation, not content, and keep in mind that the SPO2 is not the PaO2. It is also more difficult to obtain a pulse oximetry reading in the feline patient as opposed to the canine. The recommended site is the tongue, although that is not feasible if the patient is conscious. The mucus membrane is difficult to place the pulse oximeter probe on the feline patient as it is thin and generally has smaller surface area than the dog. An alternate site for pulse oximetry reading in the cat is the ear (often unreliable if the patient is hypothermic) or rectally, which requires a special probe not supplied in most pulse oximeter units.

Identifying the type of respiratory sounds in the critical patient can be difficult. Common respiratory sounds include harsh or static sounding lungs (indicative of trauma, parenchymal disease, early signs of fluid overload), crackles or popping sounds (indicative of parenchymal disease, severe fluid overload, asthma), wheezes or musical sounds (asthma or chronic bronchitis), or upper airway (referred) sounds (indicative of stenosis, elongated soft palate, tracheal collapse, or constriction), muffled or absent lung sounds (pneumothorax, hemothorax, chylothorax, or diaphragmatic hernia) or upper airway obstruction (characterized by severe inspiratory stridor and "noisy" breathing).

Respiratory emergencies can often be further categorized into the type of breathing pattern. There are typically four different breathing patterns commonly seen on emergency. Upper airway obstructions characteristically presents as a paradoxical movement of the abdomen during inspiration. The patient is often cyanotic and stressed. Examples of upper airway obstructions include laryngeal paralysis, tracheal collapse, foreign bodies, or severe upper airway edema. Emergency sedation and intubation is often necessary.