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NCT Number: NCT07843186

PCO₂ Gap and Lactate as Predictors of POCD After Cardiac Surgery

This prospective observational study aims to evaluate whether intraoperative venous-to-arterial carbon dioxide partial pressure difference (PCO₂ gap) and arterial lactate levels can serve as early predictors of postoperative cognitive dysfunction (POCD) in elderly patients undergoing elective cardiac surgery with cardiopulmonary bypass. Intraoperative measurements of PCO₂ gap and lactate will be correlated with perioperative cognitive outcomes assessed using the Montreal Cognitive Assessment (MoCA) and postoperative delirium screening using the Confusion Assessment Method for the ICU (CAM-ICU).

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Key information

Conditions

Postoperative Cognitive Dysfunction (POCD) Cardiac Surgery Cardiopulmonary Bypass Cognition Disorders Cognitive Dysfunction Mental Disorders Neurocognitive Disorders Pathologic Processes Pathological Conditions, Signs and Symptoms Postoperative Cognitive Complications Postoperative Complications

Age range

65 year and older

Sex eligibility

All sexes

Study type

Observational

About this study

This prospective observational cohort study will be conducted at El-Demerdash Hospital, Ain Shams University. Patients aged 65 years and older undergoing elective cardiac surgery with cardiopulmonary bypass will be enrolled. Serial measurements of the PCO₂ gap and arterial lactate will be obtained before induction, during CPB, at the end of CPB, 30 minutes after weaning from CPB, and immediately postoperatively. Cognitive function will be evaluated preoperatively and one month after surgery using the Montreal Cognitive Assessment (MoCA). Postoperative delirium will be assessed daily during ICU stay using CAM-ICU. The study will investigate the predictive value of intraoperative PCO₂ gap and lactate levels for postoperative cognitive dysfunction and determine potential cutoff values associated with cognitive decline.

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • Age ≥65 years.
  • Undergoing elective cardiac surgery with cardiopulmonary bypass (e.g., coronary artery bypass grafting or valve surgery).
  • American Society of Anesthesiologists (ASA) Physical Status III.
  • Able to provide written informed consent.

Exclusion criteria

  • Refusal or inability to provide written informed consent.
  • Pre-existing neurological disorders (e.g., Alzheimer's disease, Parkinson's disease, or stroke with residual neurological deficits).
  • Severe psychiatric disorders requiring active treatment.
  • History of drug or alcohol abuse.
  • Emergency cardiac surgery.
  • Significant visual or hearing impairment interfering with cognitive testing.
  • Inability to complete preoperative cognitive assessment.
  • Preoperative dementia (MoCA score <20).
  • Significant pulmonary disease (e.g., COPD or lung cancer).
  • Patients meeting the protocol-defined intraoperative or postoperative exclusion criteria.

Treatment and study plan

Primary outcomes

  1. Predictive Value of Intraoperative PCO₂ Gap and Arterial Lactate Levels for Postoperative Cognitive Dysfunction (POCD

    Time frame: Baseline (preoperative) and 1 month postoperatively

    To evaluate whether intraoperative venous-to-arterial carbon dioxide partial pressure difference (PCO₂ gap) and arterial lactate levels predict postoperative cognitive dysfunction in elderly patients undergoing elective cardiac surgery with cardiopulmonary bypass. POCD will be assessed by changes in Montreal Cognitive Assessment (MoCA) scores from the preoperative baseline to 1 month postoperatively.

Secondary outcomes

  1. Early Postoperative Delirium Assessed by the Confusion Assessment Method for the ICU (CAM-ICU)

    Time frame: Daily during the first 5 postoperative days or until ICU discharge, whichever occurs first

    To determine the occurrence of early postoperative delirium using the Confusion Assessment Method for the ICU (CAM-ICU). CAM-ICU is a dichotomous assessment (positive or negative), where a positive result indicates the presence of delirium

  2. Determination of Cutoff Values for Intraoperative PCO₂ Gap and Arterial Lactate Levels Predictive of POCD

    Time frame: 1 month postoperative

    To identify optimal cutoff values for intraoperative PCO₂ gap and arterial lactate levels associated with postoperative cognitive dysfunction in elderly patients undergoing cardiac surgery with cardiopulmonary bypass.The PCO₂ gap will be measured in mmHg, and arterial lactate concentration will be measured in mmol/L.

  3. Correlation of (CAM - ICU) to MoCA for prediction of cognitive impairmentat 5 days post operative

    Time frame: CAM-ICU: Daily during the first 5 postoperative days; MoCA: baseline preoperatively and 1 month postoperatively

    To evaluate the correlation between postoperative delirium assessed by the Confusion Assessment Method for the ICU (CAM-ICU) and postoperative cognitive function assessed by the Montreal Cognitive Assessment (MoCA).CAM-ICU will be recorded as a dichotomous result (positive or negative), with a positive result indicating the presence of delirium. MoCA will be recorded as a total score ranging from 0 to 30, with higher scores indicating better cognitive function

  4. Incidence of POCD at 1 month postoperatively, defined by a decline in MoCA scores from baseline in elderly cardiac patient.

    Time frame: Baseline (preoperative) and 1 month postoperatively

    To determine the incidence of postoperative cognitive dysfunction, defined as a decline in MoCA score from the preoperative baseline, one month after cardiac surgery

  5. Duration of Mechanical Ventilation in Relation to Intraoperative PCO₂ Gap and Arterial Lactate Levels

    Time frame: Measured from the end of surgery until successful extubation (up to 30 days)

    To evaluate the association between intraoperative PCO₂ gap and arterial lactate levels and the duration of mechanical ventilation following cardiac surgery with cardiopulmonary bypass. Duration of mechanical ventilation will be measured in hours from the end of surgery until successful extubation, as documented in the patient's medical and ventilator records.

  6. Duration of Intensive Care Unit Stay in Relation to Intraoperative PCO₂ Gap and Arterial Lactate Levels

    Time frame: From ICU admission after surgery until ICU discharge, up to 30 days

    To evaluate the association between intraoperative PCO₂ gap and arterial lactate levels and the duration of intensive care unit (ICU) stay following cardiac surgery with cardiopulmonary bypass. ICU stay will be measured in days from ICU admission after surgery until ICU discharge, as documented in the patient's medical records.

  7. Duration of Hospital Stay in Relation to Intraoperative PCO₂ Gap and Arterial Lactate Levels

    Time frame: From the end of surgery until hospital discharge, up to 30 days

    To evaluate the association between intraoperative PCO₂ gap and arterial lactate levels and the duration of hospital stay following cardiac surgery with cardiopulmonary bypass. Hospital stay will be measured in days from the end of surgery until hospital discharge, as documented in the patient's medical records.

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Sponsors and collaborators

Lead sponsor

Ain Shams University

Other

Registry information

Official study title

Intraoperative PCO₂ Gap and Lactate Levels as Early Predictors of Postoperative Cognitive Dysfunction in Elderly Patients Undergoing Cardiac Surgery With Cardiopulmonary Bypass

Important dates

Study start
2026
Primary completion
2028
Study completion
2028
First posted
Sep 25, 2026
Registry last updated
Sep 25, 2026

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

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This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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