Background Postoperative delirium (POD) is a serious complication after cardiac surgery. Use of dexmedetomidine to prevent delirium is controversial. The authors hypothesized that dexmedetomidine sedation after cardiac surgery would reduce the incidence of POD. Methods After institutional ethics review board approval, and informed consent, a single-blinded, prospective, randomized controlled trial was conducted in patients 60 yr or older undergoing cardiac surgery. Patients with a history of serious mental illness, delirium, and severe dementia were excluded. Upon admission to intensive care unit (ICU), patients received either dexmedetomidine (0.4 μg/kg bolus followed by 0.2 to 0.7 μg kg−1 h−1 infusion) or propofol (25 to 50 μg kg−1 min−1 infusion) according to a computer-generated randomization code in blocks of four. Assessment of delirium was performed with confusion assessment method for ICU or confusion assessment method after discharge from ICU at 12-h intervals during the 5 postoperative days. Primary outcome was the incidence of POD. Results POD was present in 16 of 91 (17.5%) and 29 of 92 (31.5%) patients in dexmedetomidine and propofol groups, respectively (odds ratio, 0.46; 95% CI, 0.23 to 0.92; P = 0.028). Median onset of POD was on postoperative day 2 (1 to 4 days) versus 1 (1 to 4 days), P = 0.027, and duration of POD 2 days (1 to 4 days) versus 3 days (1 to 5 days), P = 0.04, in dexmedetomidine and propofol groups, respectively. Conclusions When compared with propofol, dexmedetomidine sedation reduced incidence, delayed onset, and shortened duration of POD in elderly patients after cardiac surgery. The absolute risk reduction for POD was 14%, with a number needed to treat of 7.1.
Preoperative administration of statins is associated with the reduced risk of postoperative delirium after cardiac surgery with cardiopulmonary bypass.
Accurate measurements of arterial P CO 2 (P a,CO 2 ) currently require blood sampling because the end-tidal P CO 2 (P ET,CO 2 ) of the expired gas often does not accurately reflect the mean alveolar P CO 2 and P a,CO 2 . Differences between P ET,CO 2 and P a,CO 2 result from regional inhomogeneities in perfusion and gas exchange. We hypothesized that breathing via a sequential gas delivery circuit would reduce these inhomogeneities sufficiently to allow accurate prediction of P a,CO 2 from P ET,CO 2 . We tested this hypothesis in five healthy middle-aged men by comparing their P ET,CO 2 values with P a,CO 2 values at various combinations of P ET,CO 2 (between 35 and 50 mmHg), P O 2 (between 70 and 300 mmHg), and breathing frequencies (f ; between 6 and 24 breaths min −1 ). Once each individual was in a steady state, P a,CO 2 was collected in duplicate by consecutive blood samples to assess its repeatability. The difference between P ET,CO 2 and average P a,CO 2 was 0.5 ± 1.7 mmHg (P = 0.53; 95% CI −2.8, 3.8 mmHg) whereas the mean difference between the two measurements of P a,CO 2 was −0.1 ± 1.6 mmHg (95% CI −3.7, 2.6 mmHg). Repeated measures ANOVAs revealed no significant differences between P ET,CO 2 and P a,CO 2 over the ranges of P O 2 , f and target P ET,CO 2 . We conclude that when breathing via a sequential gas delivery circuit, P ET,CO 2 provides as accurate a measurement of P a,CO 2 as the actual analysis of arterial blood. Accurate measurement of arterial P CO 2 (P a,CO 2 ) is important for the clinical assessment of patients and, in physiological studies, for the assessment of control of breathing and cerebral blood flow. Currently, the reference standard for measuring P a,CO 2 is analysis of arterial blood via direct arterial puncture. This invasive approach has a number of disadvantages for both the subject (discomfort and potential arterial wall damage) and investigator (restricted mobility of the catheter insertion site, cost, time delay for blood analysis, and limited temporal resolution of changes in P a,CO 2 ). As a result, investigators have long sought a suitable non-invasive method to measure P a,CO 2 .Non-invasive methods of predicting P a,CO 2 from alveolar P CO 2 (P A,CO 2 ) consider the lung to be a tonometer in which CO 2 equilibrates between alveolar gas and capillary blood. In reality, however, the lung is not a single homogeneous time-invariant gas exchange compartment. Rather, P CO 2 varies in different regions of the lung as a result of differences in ventilation-to-perfusion matching (V A /Q ) throughout the lung and, in each lung region, throughout the respiratory cycle (Dubois et al. 1952;Lenfant, 1967). The contribution to the P a,CO 2 of blood passing each alveolus reflects the average P CO 2 in that alveolus during the respiratory cycle (Jones et al. 1979;Robbins et al. 1990). P a,CO 2 , then, reflects the timeand flow-weighted averages of all alveolar ventilatory fluctuations in allV A /Q regions throughout the lung, i.e. the mean P A,CO 2 (Lenfant, 1967). As a result, the r...
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.