Q&A: Complications Of Acute Respiratory Failure

Respiratory failure results from inadequate gas exchange by the respiratory system due to various causes, such that arterial oxygen, carbon dioxide or both are not maintained at normal levels resulting in hypoxemia, hypercapnia or both. Respiratory failure is classified as either Type 1 or Type 2, based on carbon dioxide levels, and can be either acute or chronic. Respiratory failure may result in altered mental status due to cerebral ischemia. The normal partial pressure reference values are: oxygen PaO2 more than 80 mmHg (11 kPa), and carbon dioxide PaCO2 less than 45 mmHg (6.0 kPa).

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This is a Question & Answer revision article designed for medical students and professionals preparing for the PLAB, MRCP or USMLE examinations. They are based on actual questions from these examinations. You may find the Pneumonia article more useful, or one of our many articles on Diseases & Conditions, Medical Syndromes, Health & Wellness or Home Remedies.

In this article:
MCQ exam: clinical scenario
MCQ exam: answer
MCQ exam: explanation

MCQ exam: clinical scenario

A 60 year old man with a two day history of cough productive of rusty brown sputum, pleuritic chest pain and fever is admitted into the Emergency Department. Which of the following is a common cardiovascular complication in patients with acute respiratory failure?

a). Hypertension
b). Endocarditis
c). Aortic coarctation
d). Coronary artery spasm
e). Increased cardiac output

MCQ exam: answer

The correct answer is B.

MCQ exam: explanation

Complications of acute respiratory failure may be pulmonary, cardiovascular, gastrointestinal (GI), infectious, renal, or nutritional.

Common pulmonary complications of acute respiratory failure include pulmonary embolism, barotrauma, pulmonary fibrosis, and complications secondary to the use of mechanical devices. Patients are also prone to develop nosocomial pneumonia. Regular assessment should be performed by periodic radiographic chest monitoring. Pulmonary fibrosis may follow acute lung injury associated with ARDS. High oxygen concentrations and the use of large tidal volumes may worsen acute lung injury.

Common cardiovascular complications in patients with acute respiratory failure include hypotension, reduced cardiac output, arrhythmia, endocarditis, and acute myocardial infarction. These complications may be related to the underlying disease process, mechanical ventilation, or the use of pulmonary artery catheters.

The major GI complications associated with acute respiratory failure are hemorrhage, gastric distention, ileus, diarrhea, and pneumoperitoneum. Stress ulceration is common in patients with acute respiratory failure; the incidence can be reduced by routine use of antisecretory agents or mucosal protectants.

Nosocomial infections, such as pneumonia, urinary tract infections, and catheter-related sepsis, are frequent complications of acute respiratory failure. These usually occur with the use of mechanical devices. The incidence of nosocomial pneumonia is high and associated with significant mortality.

Regarding renal complications, acute renal failure and abnormalities of electrolytes and acid-base homeostasis are common in critically ill patients with respiratory failure. The development of acute renal failure in a patient with acute respiratory failure carries a poor prognosis and high mortality. The most common mechanisms of renal failure in this setting are renal hypoperfusion and the use of nephrotoxic drugs (including radiographic contrast material).

Nutritional complications include malnutrition and its effects on respiratory performance and complications related to administration of enteral or parenteral nutrition. Complications associated with nasogastric tubes, such as abdominal distention and diarrhea, also may occur. Complications of parenteral nutrition may be mechanical (resulting from catheter insertion), infectious, or metabolic (eg, hypoglycemia, electrolyte imbalance).