Impact of clonidine administration on delirium and related respiratory weaning after surgical correction of acute type-A aortic dissection: results of a pilot study.

Delirium and transient neurologic dysfunctions (TND) often complicate the postoperative course after surgery for acute type-A aortic dissection (AAD). We evaluated the role of clonidine on neurological outcome and respiratory function in 30 consecutive patients undergoing surgery for AAD. Patients were prospectively randomized to receive either clonidine (0.5 microg/kg bolus, followed by continuous infusion at 1-2 microg/kg/h) or placebo (NaCl 0.9%) in on starting and throughout the weaning period from the mechanical ventilation. Incidence of delirium and TND, Delirium Detection Score (DDS), weaning parameters [respiratory rate to tidal volume ratio - f/VT; pressure-frequency product (PFP); partial pressure of arterial oxygen to fractional inspired oxygen concentration (PaO(2)/FiO(2)); partial pressure of carbon dioxide (PaCO(2))], weaning duration and intensive care unit (ICU) length of stay were recorded. The two groups were similar for preoperative and operative variables and also for the incidence of postoperative complications. DDS was lower in the clonidine group (P<0.001). Patients weaned with clonidine showed lower f/VT and PFP, higher PaO(2)/FiO(2) and PaCO(2), lower DDS, weaning period and the related ICU length of stay (P<0.001). This was further confirmed in patients developing delirium/TND. Intravenous clonidine after surgery for AAD reduces the severity of delirium, improves the respiratory function, shortens the weaning duration and the ICU length of stay.