Hypothermia, Rewarming
Conditions
Keywords
Cardiopulmonary bypass, Afterdrop, Deep Hypothermic Circulatory Arrest, Heated Humidified Breathing Circuit
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.
Interventions
DEVICEHeated Humidified Breathing Circuit and Forced Air Blanket
Heated humidified breathing circuits (ANAPOD) will be set up and managed by respiratory therapist in standard fashion defined by the manufacturer. Temperate will be set at 41C. Forced air warming blankets will be set at 42C for duration of rewarming.
Sponsors
Duke University
Study design
Allocation
NA
Intervention model
SINGLE_GROUP
Primary purpose
TREATMENT
Masking
NONE
Intervention model description
The intervention group has only one arm. All patients will use active warming via traditional methods (ie forced air warming blankets) and Heated Humidified breathing circuits (HHBC) via ANAPOD Heated Humidification System® (ANAPOD). Those patients will be matched with a retrospective historical cohort of patients that received active warming via traditional methods only (forced air warming blankets).
Eligibility
Sex/Gender
ALL
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
* Admission to intensive care unit following surgical procedure involving cardiopulmonary bypass. * Admission temperature ≤ 35.0 C.
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.
Design outcomes
Primary
| Measure | Time frame | Description |
|---|---|---|
| Time to Normothermia | up to 24 hours post admission to intensive care unit | Core temperature normothermia defined as \>=36.5 C. |
Secondary
| Measure | Time frame | Description |
|---|---|---|
| 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. |
| 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 Prothrombin Time | 24 hours post admission to intensive care unit | Laboratory assessment of Prothrombin Time with normal defined as 9.5-13.1 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. |
| 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. |
| 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. |
| 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. |
Countries
United States
Participant flow
Participants by arm
| Arm | Count |
|---|---|
| HHBC and Forced Air Warming 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.
Heated Humidified Breathing Circuit and Forced Air Blanket: Heated humidified breathing circuits (ANAPOD) will be set up and managed by respiratory therapist in standard fashion defined by the manufacturer. Temperate will be set at 41C.
Forced air warming blankets will be set at 42C for duration of rewarming. | 14 |
| Total | 14 |
Baseline characteristics
| Characteristic | HHBC and Forced Air Warming |
|---|---|
| Age, Continuous | 65.4 years STANDARD_DEVIATION 14.9 |
| Race (NIH/OMB) American Indian or Alaska Native | 0 Participants |
| Race (NIH/OMB) Asian | 1 Participants |
| Race (NIH/OMB) Black or African American | 2 Participants |
| Race (NIH/OMB) More than one race | 0 Participants |
| Race (NIH/OMB) Native Hawaiian or Other Pacific Islander | 0 Participants |
| Race (NIH/OMB) Unknown or Not Reported | 0 Participants |
| Race (NIH/OMB) White | 11 Participants |
| Region of Enrollment United States | 14 Participants |
| Sex: Female, Male Female | 5 Participants |
| Sex: Female, Male Male | 9 Participants |
| Temperature at ICU admission | 34 Degrees Celsius |
Adverse events
| Event type | EG000 affected / at risk |
|---|---|
| deaths Total, all-cause mortality | 1 / 14 |
| other Total, other adverse events | 8 / 14 |
| serious Total, serious adverse events | 2 / 14 |
Outcome results
Primary
Time to Normothermia
Core temperature normothermia defined as \>=36.5 C.
Time frame: up to 24 hours post admission to intensive care unit
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HHBC and Forced Air Warming | Time to Normothermia | 4.4 hours |
Secondary
Coagulopathy as Measured by Need for Transfusion of Blood Product
Assessed via number of transfusions of red blood cells, fresh frozen plasma, platelets, cryoprecipitate.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HHBC and Forced Air Warming | Coagulopathy as Measured by Need for Transfusion of Blood Product | 0 Units transfused |
Secondary
Metabolic Derangement as Measured by Time to Normal pH
Assessed via blood gas analysis. Normal pH defined as 7.35-7.45.
Time frame: up to 24 hours post admission to intensive care unit
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HHBC and Forced Air Warming | Metabolic Derangement as Measured by Time to Normal pH | 0.4 hours |
Secondary
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Act Partial Thromboplastin Time
Laboratory assessment of Act Partial Thromboplastin Time with normal defined as 26.8-37.1 seconds.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| HHBC and Forced Air Warming | Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Act Partial Thromboplastin Time | 10 Participants |
Secondary
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Fibrinogen.
Laboratory assessment of fibrinogen levels with normal defined as 213-435 mg/dL.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| HHBC and Forced Air Warming | Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Fibrinogen. | 5 Participants |
Secondary
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of INR
Laboratory assessment of international normalised ratio (INR) with normal defined as 0.9-1.1.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| HHBC and Forced Air Warming | Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of INR | 12 Participants |
Secondary
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Platelet Count
Laboratory assessment of platelet count with normal defined as 150 - 450 x10ˆ9/L.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| HHBC and Forced Air Warming | Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Platelet Count | 7 Participants |
Secondary
Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Prothrombin Time
Laboratory assessment of Prothrombin Time with normal defined as 9.5-13.1 seconds.
Time frame: 24 hours post admission to intensive care unit
| Arm | Measure | Value (COUNT_OF_PARTICIPANTS) |
|---|---|---|
| HHBC and Forced Air Warming | Number of Subjects With Abnormal Coagulopathy as Measured by Laboratory Assessment of Prothrombin Time | 12 Participants |
Secondary
Time to Extubation
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.
Time frame: up to 24 hours post admission to intensive care unit
| Arm | Measure | Value (MEDIAN) |
|---|---|---|
| HHBC and Forced Air Warming | Time to Extubation | 5.4 hours |