THORACIC AND RESPIRATORYDISORDERS■ Early intubation if signs of airway edema and obstruction
■ Bronchodilators may be helpful.
■ Antibiotics are not helpful.
■ Steroids may be helpful in nitrogen oxide poisoning to prevent bronchiolitis
obliterans.
■ Cyanide antidote kit in hydrogen sulfide poisoning
COMPLICATIONS
Pulmonary edema(often delayed) from a chemical pneumonitis is a com-
mon complication among most toxic gases, fumes, and vapors. Other possible
complications include:
■ Nitrogen oxides:Methemoglobinemia bronchiolitis obliterans
■ Ammonia: Corneal burns
■ Hydrocarbons:Persistent airway irritation, CNS depression, peripheral
neuropathy, dysrhythmias, hepatic toxicity, eg, CCl 4 , renal failure, blood
dyscrasias
■ Hydrogen sulfide:Severe metabolic acidosis
CYSTIC FIBROSISThis is the most common lethal autosomal-recessive disorder in Caucasians,
affecting 1 in 3500 births. It is classically characterized by multisystem
involvement of the sinuses, lungs, pancreas, liver, gallbladder, intestines, bones,
and, in males, the vas deferens.
CAUSES
CF is caused by mutations in the CF transmembrane conductance regulator
(CFTR)→chloride channel dysfunction.
SYMPTOMS/EXAM
■ Most CF patients are diagnosed during childhood. A history of failure to
thrive as a child, persistent respiratory infections (Pseudomonas), nasal
polyposis, sinusitis, intestinal obstruction, malabsorption, recurrent pan-
creatitis, hepatobiliary disease, and male infertility are suggestive of CF.
■ Seven percent of CF patients are diagnosed as adults, and these patients
tend to present with upper lobe bronchiectasis.
■ Exammay reveal ↑chest AP diameter, upper lung field crackles, nasal
polyps, hepatomegaly, and clubbing.
■ Acute exacerbations are typically characterized by ↑sputum production,
dyspnea, fatigue, weight loss, and a decline in FEV 1.
DIFFERENTIAL
Immunodeficiency, asthma, ABPA
DIAGNOSIS
Diagnosis requires both clinical and laboratory evidence of CFTR dysfunction.
■ Sweat chloride concentration: The best screening test for CF for a patient
with a suggestive clinical picture; normal sweat chloride is <40 mmol/L
■ Genotyping: Screening for the presence of two CFTR mutations known
to cause CF; newer tests screen for >1000 different known mutations
Although most CF patients are
diagnosed in childhood, 7%
are diagnosed as adults and
tend to have upper-lobe
bronchiectasis.