Heated Humidified Breathing Circuit Rewarming in Hypothermic Post Cardiopulmonary Bypass Patients.

Not Applicable

Completed

• Conditions: Hypothermia; Rewarming
• Interventions: Device: Heated Humidified Breathing Circuit and Forced Air Blanket

• Registration Number: NCT03697122
• Lead Sponsor: Duke University

Brief Summary

Hypothermia on admission to the intensive care unit (ICU) following cardiopulmonary bypass (CPB) is common. The investigators propose that rewarming hypothermic (≤ 35 C) patients admitted to the intensive care unit following procedures using CPB with heated humidified breathing circuits (HHBC) in addition to conventional forced air warming blankets will shorten time to normothermia. Secondarily it may shorten time to extubation, improve coagulopathy, and metabolic derangements seen with hypothermia.

Detailed Description

Hypothermia on admission to the intensive care unit (ICU) following cardiopulmonary bypass (CPB) is common. Cooling and rewarming during CPB and deep hypothermic circulatory arrest (DHCA) takes considerable time and contributes to the post-procedural coagulopathy and physiologic perturbations. Core body parts (trunk and head) rewarm more quickly than peripheral parts (extremities). After disconnecting from CPB the body is allowed to self equilibrate. The normal vasoconstriction response is impaired by the administered anaesthesia. Hence, heat distribution takes place from the warm core to the colder periphery. This causes an afterdrop: a decrease in the temperature of the core organs. After-drop may contribute to post-operative complications such as shivering, coagulopathy, increased myocardial stress, increased wound infections, metabolic acidosis, delayed extubation and prolonged ICU length of stay (LOS).

The use of the active warming via traditional methods (ie forced air warming blankets) and Heated Humidified breathing circuits (HHBC) via ANAPOD Heated Humidification System® (ANAPOD) may shorten time to normothermia. Secondarily it may shorten time to extubation, improve coagulopathy, and metabolic derangements seen with hypothermia.

Sample and Study Design- The investigators will prospectively collect data for 14 enrolled non-patients who will receive active warming via both forced air warming blankets and Heated Humidified breathing circuits (HHBC). Retrospective data will be obtained retrospectively for 28 matched patients from two years prior to initiation of the trial, who received warming only via forced air warming blankets.

Data Collection Plan- Data will be extracted and collected by the Duke Department of Anesthesiology IT analyst, who will review and extract information from the patient's chart via Epic/ Maestro Care, or manually if necessary.

Data Evaluation- Descriptive statistics will be used to evaluate patient demographics and clinical characteristics. Descriptive statistics will be summarized as mean ± (SD) or median (interquartile range) for continuous variables and group frequencies (%) for dichotomous or categorical variables.

As all patients are expected to achieve normothermia within the study period, the primary outcome of time to normothermia will be analyzed as a numeric outcome variable. Following validation of distributional assumptions the investigators will compare the time to normothermia between the two groups via t-test or Wilcoxon rank sum test as appropriate. It is expected that the patients will reach normothermia between 45 minutes and 6 hours after admission to the ICU.

By using a 2:1 matching ratio and a moderate level of variability (SD=1.3 hours) a study of 14 prospectively enrolled patients and 28 retrospectively matched patients would attain 82% power to detect a 1.25 hour difference between time to normothermia in the prospective group (active warming via traditional methods (ie forced air warming blankets) and Heated Humidified breathing circuits (HHBC) via ANAPOD Heated Humidification System® (ANAPOD), and the retrospective group (active warming via traditional methods (ie forced air warming blankets only) at alpha level 0.05.

Secondary numeric outcomes such as time to extubation, time to normal PH, and coagulopathy lab values will be analyzed by t-test or Wilcoxon rank sum test as appropriate. Differences in categorical outcomes between treatment groups will be analyzed via chi-square or fisher exact tests. As the patients will be matched on key confounders no further adjustment is expected to be necessary, so the moderate sample size should not limit the primary analysis. Potential subgroup analysis may be conducted in an exploratory analysis to determine if the treatment effect of ANAPOD warming is different by procedure type or patient/surgical characteristics.

Study Timeline

• Study First Submitted: 2018-09-27
• Study First Submitted QC: 2018-10-03
• Study First Posted: 2018-10-05
• Study Start: 2019-04-01
• Primary Completion: 2019-06-15
• Study Completion: 2019-06-15
• Results First Submitted: 2020-06-15
• Results First Submitted QC: 2020-06-15
• Status Verified: 2020-07
• Results First Posted: 2020-07-02
• Last Update Submitted: 2020-07-02
• Last Update Posted: 2020-07-15

Recruitment & Eligibility

• Status: COMPLETED
• Sex: All
• Target Recruitment: 14

Inclusion Criteria

• Admission to intensive care unit following surgical procedure involving cardiopulmonary bypass.
• Admission temperature ≤ 35.0 C.

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Exclusion Criteria

• Patients placed on extracorporeal membrane oxygenation intra-operatively, or during first 24 hours after ICU admission.
• Any additional surgical procedures in the first 24 hours days after initial surgery e.g. Chest exploration for bleeding, Open Chest, Non-cardiac surgery such as colectomy for ischemic gut, etc.

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: SINGLE_GROUP

Arm && Interventions

Group	Intervention	Description
HHBC and Forced Air Warming	Heated Humidified Breathing Circuit and Forced Air Blanket	Patients admitted to intensive care unit hypothermic (≤ 35 C) following surgical procedures involving cardiopulmonary bypass. Will be rewarmed with heated humidified breathing circuits (ANAPOD) and standard forced air warming blankets.

Primary Outcome Measures

Name	Time	Method
Time to Normothermia	up to 24 hours post admission to intensive care unit	Core temperature normothermia defined as \>=36.5 C.

Secondary Outcome Measures

Name	Time	Method
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Act Partial Thromboplastin Time	24 hours post admission to intensive care unit	Laboratory assessment of Act Partial Thromboplastin Time with normal defined as 26.8-37.1 seconds.
Time to Extubation	up to 24 hours post admission to intensive care unit	Time from admission to time of extubation. Followup was truncated at 24 hours and if patient had not been extubated at that time they were assigned a value of 24 hours.
Coagulopathy as Measured by Need for Transfusion of Blood Product	24 hours post admission to intensive care unit	Assessed via number of transfusions of red blood cells, fresh frozen plasma, platelets, cryoprecipitate.
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Prothrombin Time	24 hours post admission to intensive care unit	Laboratory assessment of Prothrombin Time with normal defined as 9.5-13.1 seconds.
Metabolic Derangement as Measured by Time to Normal pH	up to 24 hours post admission to intensive care unit	Assessed via blood gas analysis. Normal pH defined as 7.35-7.45.
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of INR	24 hours post admission to intensive care unit	Laboratory assessment of international normalised ratio (INR) with normal defined as 0.9-1.1.
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Fibrinogen.	24 hours post admission to intensive care unit	Laboratory assessment of fibrinogen levels with normal defined as 213-435 mg/dL.
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Platelet Count	24 hours post admission to intensive care unit	Laboratory assessment of platelet count with normal defined as 150 - 450 x10ˆ9/L.

Trial Locations

Locations (1)

Duke University Hospital; 🇺🇸 Durham, North Carolina, United States