During mechanical ventilation, a patient with a closed head injury develops the Cushing re-sponse. This may be immediately managed by using which of the following?

a. Pressure-controlled continuous mandatory ventilation (PC-CMV) with positive end- expiratory pressure (PEEP)
b. Sedation and paralysis
c. Permissive hypercapnia
d. Iatrogenic hyperventilation

ANS: D
The Cushing response is the normal response to acute increases in intracranial pressure (ICP). This includes hypertension with bradycardia. Iatrogenic hyperventilation, although controversial, is recommended when there is acute uncontrolled increased ICP. The partial pressure of carbon di-oxide in the arteries (PaCO2) should be maintained between 25 and 30 mm Hg or titrated to the ICP if it is being monitored. This is a temporary solution and should be gradually reversed within 24-48 hours, allowing acid-base balance to restore itself. The use of pressure-controlled continu-ous mandatory ventilation (PC-CMV) and positive end-expiratory pressure (PEEP) can increase ICP further. Sedation and paralysis should only be used in extreme cases when the ventilator and patient are asynchronous (usually with severe asthma). Permissive hypercapnia may result in fur-ther increases in ICP.