Respiratory failure is failure to meet the demands of the body for the exchange of oxygen and carbon dioxide. Presentation can be as severe respiratory distress or frank respiratory arrest. This topic outlines an approach to the evaluation, diagnosis, and treatment of respiratory failure. Space constraints necessitate prior mastery of ACLS and ATLS protocols.

Patient history in an emergency, is obtainable using the "ATLS AMPLE' history guideline. In a less urgent setting, a full problem-oriented ROS is indicated. Determine the time of onset and duration of symptoms, underlying pathology (i.e. CHF, asthma), evidence of infection or trauma, possibility of exposure to toxins, and ingestion of drugs.

Physical exam and lab studies

Physical exam emphasizes the ABCs. Is the patient breathing? Note the rate, pattern, and character of breathing. Can air movement be auscultated? Note the presence of stridor, wheezing, bilateral breath sounds, paradoxical chest wall movement, rales, rhonchi, accessory muscle use, and retractions. Is the airway threatened by bleeding, neck, or facial trauma? Is the patient cyanotic? Initial BCLS, ACLS therapy should not be delayed by diagnostic tests. When the airway is established, then other testing should include a CXR, CBC with diff., ABG, and blood or urine toxicology screen. The CXR may yield evidence of infection, pneumothorax, fractures, effusions, pulmonary edema, foreign bodies (FBs), or masses. The CBC and diff. may show an increased WBC count (infection?) or a decreased Hb/Hct This could indicate blood loss or chronic anemia. The ABG will show adequacy of ventilation (pC02) and oxygenation (pO2) and may be followed serially to direct treatment. The base excess on the ABG demonstrates metabolic or respiratory acidosis or alkalosis. These concepts should be reviewed. The toxicology screen may rule out commonly abused drugs.

Respiratory failure can result from trauma, infection, chronic cardiovascular or pulmonary disease, bronchospasm, foreign body aspiration, metabolic or CNS disorders, neuromuscular disease, toxins, and drug overdose. Using the history, physical exam, and laboratory tools described previously, a differential diagnosis in order of probability should be generated to guide treatment.

Treatment of respiratory distress should begin with the initial assessment. Correct positioning of the airway or the use of airway adjuncts (oral or nasal airways as per ACLS manual) should relieve airway obstruction. Endotracheal intubation is indicated per ACLS, ATLS protocol to secure the airway that remains obstructed or to establish the airway in the unconscious, apneic patient. An emergency cricothyrotomy (ATLS guidelines) should be considered if intubation is impossible. Elective intubation should be considered in the patent but deteriorating airway (some facial trauma, CNS lesions, all airway burns including live stream, or closed space fires). Oxygen is vital. Administer the highest concentration of oxygen available to apneic patients with a bag-valve-mask, or via an ETT. Cases of respiratory distress should have oxygen administered ASAP. In addition to oxygen, naloxone is the treatment for patients in narcotic overdose (0.4 mg IV q 2-3 min) and atropine in organophosphate poisoning (1 mg doses IV every 5 minutes until bronchospasm, secretions, and bradycardia abate). Clinically significant pneumothoraces should be relieved with a needle thoracotomy in the 2^nd intercostal space, mid-clavicular line. After this procedure, a chest tube should be placed (ATLS guidelines) with a follow up CXR to determine tube placement and re-evaluate therapy.

All information obtained in the history, physical exam, including lab / x-ray procedures described previously should be documented. Mild exacerbations of existing conditions responding to therapy may be treated in an outpatient setting or referred on a less urgent basis. Patients in respiratory distress with a patent airway should be referred for definitive care in an urgent manner with a MO in attendance. Patients presenting in respiratory arrest/requiring intubation or other airway intervention should be emergently referred for definitive care. Consult and refer appropriately if doubt exists about a patient's condition.

Reference

1. Textbook of ACLS. 1987, Chapter 3, pp. 27-39.

2. Critical Care. Civetta, 1988, section 2, pp. 1023-1189.