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Intraoperative hypotension and 1-year mortality after noncardiac surgery
Jilles B Bijker1, Wilton A van Klei, Yvonne Vergouwe
1Division of Perioperative Care and Emergency Medicine, Department of Anesthesiology, University Medical Center Utrecht, Utrecht, The Netherlands. j.b.bijker@umcutrecht.nl
Insights
Intraoperative hypotension (IOH) did not show a direct link to 1-year mortality in noncardiac surgery patients. However, prolonged IOH in elderly patients may increase mortality risk, with duration depending on blood pressure thresholds.
Area of Science:
- Anesthesiology and Perioperative Medicine
- Surgical Outcomes Research
- Geriatric Medicine
Background:
- Intraoperative hypotension (IOH) is a common complication during surgery.
- A clear definition and consensus on IOH's impact on mortality are lacking.
- IOH is suspected to be associated with adverse outcomes, including 1-year mortality.
Purpose of the Study:
- To investigate the association between various definitions of intraoperative hypotension (IOH) and 1-year mortality after noncardiac surgery.
- To explore the influence of different blood pressure thresholds and episode durations on mortality risk.
- To identify specific patient populations, such as the elderly, who may be more vulnerable to IOH.
Main Methods:
- A cohort study of 1,705 adult patients undergoing general and vascular surgery.
- Data collected from electronic health records, including intraoperative blood pressure and confounding variables.
- Statistical analyses included multivariable Cox proportional hazard regression and classification and regression tree (CART) analysis.
- Mortality data tracked for up to 1 year post-surgery.
Main Results:
- Overall 1-year mortality was 5.2% (88 patients).
- Cox regression analysis revealed no significant association between IOH (across various definitions) and 1-year mortality after adjusting for confounders.
- CART analysis identified IOH as a predictor of 1-year mortality specifically in elderly patients.
- The duration of IOH associated with increased mortality risk in the elderly decreased as the blood pressure threshold for hypotension was lowered.
Conclusions:
- No causal relationship was established between intraoperative hypotension (IOH) and 1-year mortality in the general surgical population, irrespective of the definition used.
- For elderly patients, prolonged IOH appears to increase mortality risk, with the critical duration being dependent on the hypotension's severity (blood pressure threshold).
- The findings suggest that the impact of IOH on mortality is complex and potentially population-specific, particularly in older adults.
- Further research is needed to establish definitive lowest acceptable intraoperative blood pressure levels and their clinical implications.
Background:
Intraoperative hypotension (IOH) is frequently associated with adverse outcome such as 1-yr mortality. However, there is no consensus on the correct definition of IOH. The authors studied a number of different definitions of IOH, based on blood pressure thresholds and minimal episode durations, and their association with 1-yr mortality after noncardiac surgery.
Methods:
This cohort study included 1,705 consecutive adult patients who underwent general and vascular surgery. Data on IOH and potentially confounding variables were obtained from electronic record-keeping systems. Mortality data were collected up to 1 yr after surgery. The authors used two different techniques to reduce the influence of confounding variables, multivariable Cox proportional hazard regression modeling and classification and regression tree analysis.
Results:
The mortality within 1 yr after surgery was 5.2% (88 patients). After adjustment for confounding, the Cox regression analysis did not show an association between IOH and the risk of dying within 1 yr after surgery (hazard ratio around 1.00 with high P values for different definitions of IOH). Additional classification and regression tree analysis identified IOH as a predictor for 1-yr mortality in elderly patients. When the blood pressure threshold for IOH was decreased, the duration of IOH at which this association was found was decreased as well.
Conclusions:
This observational study showed no causal relation between IOH and 1-yr mortality after noncardiac surgery for any of the definitions of IOH. Nevertheless, additional analysis suggested that for elderly patients, the mortality risk increases when the duration of IOH becomes long enough. The length of this duration depends on the designated blood pressure threshold, suggesting that lower blood pressures are tolerated for shorter durations. The effect of IOH on 1-yr mortality remains debatable, and no firm conclusions on the lowest acceptable intraoperative blood pressures can be drawn from this study.
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