Clinical surgery-American
Intraoperative myocardial acidosis as a risk for hospital readmission after cardiac surgery

https://doi.org/10.1016/j.amjsurg.2009.01.013Get rights and content

Abstract

Background

This study elucidates the relationship between intraoperative myocardial acidosis/ischemia and the risk of unplanned hospital readmissions within 30 days and 6 months after cardiac surgery.

Methods

Myocardial tissue pH (corrected to 37°C: pH37C) was monitored in 221 patients during cardiac surgery. Regional myocardial acidosis was defined in terms of specific pH thresholds.

Results

Fourteen percent and 27% of the patients were readmitted within 30 days and 6 months postoperatively, respectively. The mean number of readmissions was 1.67 ± 1.24; pH37C <6.85 at the end of cardiopulmonary bypass (CPB) was identified as the threshold most significantly associated with readmission. This threshold was associated with a 6-fold increased risk of readmission within 30 days and a 5-fold increased risk within 6 months.

Conclusions

Persistent regional myocardial acidosis after weaning from CPB independently determines unplanned readmission rates up to 6 months postoperatively. This study underscores the importance of avoiding myocardial tissue acidosis during cardiac surgery.

Section snippets

Patient population

Between 1982 and 2001, 697 patients underwent intraoperative online monitoring of myocardial tissue pH at the Veterans Affairs (VA) Medical Center, West Roxbury, MA. Complete pH and outcomes data were available for 221 patients, who constituted the study population.

pH37C measurement

Myocardial tissue pH corrected to 37°C (pH37C) was measured by using the Khuri Tissue pH Monitoring System (Vascular Technology, Inc, Lowell, MA) in adult patients undergoing cardiopulmonary bypass as previously described.12, 14, 15,

Results

The postoperative readmission rates in our study population were 14% (28/203) and 27% (59/218) within 30 days and 6 months, respectively. Table 1 shows the major causes of readmission, the most frequent being cardiac in origin at both 30 days (43%) and 6 months (54%) postoperatively.

There were no deaths during readmission for both 30 days and 6 months. Of all the patients readmitted up to 6 months postoperatively, only 34 (58%) were readmitted to our hospital; the rest were readmitted to other

Comments

This study, which was conducted in 221 patients undergoing cardiac surgery, shows that, at the end of cardiopulmonary bypass, a myocardial tissue pH37C of 6.85 defines an acidosis threshold below which the risk of unplanned hospital readmissions is significantly increased. This pH37C threshold was associated with a 6-fold increase in the risk of unplanned readmission within 30 days and a 5-fold increase within 6 months.

Although data on mortality, morbidity, and other indexes of quality of care

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    • Cited by (3)

    • Early readmission for congestive heart failure predicts late mortality after cardiac surgery

      2012, Journal of Thoracic and Cardiovascular Surgery
      Citation Excerpt :

      This study found older age, female gender, CHF, and increased cardiopulmonary bypass time to be significantly associated with 30-day readmission. Kumbhani and colleagues8 reported intraoperative myocardial acidosis to also predict readmission after cardiac surgery. This variable was not analyzed in this study, but this and other surgical complications are also potential risk factors for readmission.

    • A case-control study of readmission to the intensive care unit after cardiac surgery

      2013, Medical Science Monitor

    • Determinants of preventable readmissions in the United States: A systematic review

      2010, Implementation Science

    Supported by the Richard Warren Surgical Research and Educational Fund, Westwood, MA.

    †

    Dr Khuri is deceased.

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    Published by Elsevier Inc.