Introduction
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.
History
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.
Differential diagnosis
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
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 2nd 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.
Summary
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
-
Textbook of ACLS. 1987, Chapter 3, pp. 27-39.
-
Critical Care. Civetta, 1988, section 2, pp. 1023-1189.
Reviewed by CAPT T. Catchings, MC, USN, Pulmonary Department, National Naval
Medical Center, Bethesda, MD (1999).