All of the following statements about the physiology of mechanical ventilation are true EXCEPT:
ExplanationPatients initiated on mechanical ventilation require a variety of supportive measures. Sedation and analgesia with a combination of benzodiazepines and narcotics are commonly used to maintain patient comfort and safety while mechanically ventilated. Recent studies have shown the utility of minimizing sedation in critically ill patients. However, adequate pain control is an essential coponent of patient comfort. In addition, patients are immobilized and are thus at high risk for development of deep venous thrombosis and pulmonary embolus. Prophylaxis with unfractionated heparin or low-molecular-weight heparin should be administered subcutaneously. Prophylaxis against diffuse gastrointestinal mucosal injury is also indicated, particularly in individuals with neurologic insult and those with severe respiratory failure and adult respiratory distress syndrome. Gastric acid suppression can be managed with H 2-receptor antagonists, proton pump inhibitors, and sucralfate. It is also recommended that individuals who are expected to be intubated for more than 72 hours receive nutritional support. Prokinetic agents are often required. Frequent positional changes and close surveillance for skin breakdown should be instituted in all intensive care units to minimize development of decubitus ulcers. In the past, frequent ventilator circuit changes had been studied as a measure for prevention of ventilator-associated pneumonia, but they were ineffective and may even have increased the risk of ventilator-associated pneumonia.
