Effect of a Warming Mattress on Perioperative Hypothermia Following Cesarean Delivery
Phase: NA
Conditions: Postoperative Hypothermia
Sponsor: Cedars-Sinai Medical Center

 
Effect of Warming Mattress on Perioperative Hypothermia Following Cesarean 
Delivery ID:Pro00039382.  3.30.17 
I. Study Design:  
This will be a randomized controlled double blinded study. 
Our study will include 100 patients having elective cesarean section at Cedars-Sinai 
Medical Center. Patients will be randomized in two groups: the first group will 
receive active warming with VitaHeat underbody heating mattress in preoperative 
holding area for 15 min, during the surgery and in PACU; second group will not 
receive active forced air or resistive mattress warming; both groups will receive the 
standard patient blankets and warmed intravenous fluids.   
 
The observer and patient will be blinded as to the group assignment. Another 
anesthesiologist will perform the randomization table and turn the VitaHeat 
warming mattress on or off.   
 
2. Study Device  
VitaHeat will loan the underbody heating mattresses for the duration of the study.  
 
 
3. Inclusion/Exclusion  
Inclusion criteria: 
• will be age >18 years,  
• singleton pregnancy >37 weeks,  
• neuraxial anesthesia,  
• healthy afebrile patients.  
 
Exclusion criteria:  
• severe uncontrolled medical problems (e.g. uncontrolled diabetes),  
• preeclampsia,  
• pre-operative temperature >38degrees C,   
• BMI>40kg/m2.   
• Neonates of uncertain viability 
• Nonviable neonates 
 
4. Study Procedures 
Patient temperature will be measured with Exergen temporal scanner TAT -5000 at 
the following events and intervals: in preoperative area, at time of neuraxial block 
(anesthesia) is placed, at delivery of the fetus, then every 15 min, at application of 
wound dressing, on arrival to recovery, then q 15 min until normothermia is 
achieved.  
 
Shivering will be recorded and graded on the following scale as used in previous 
studies:  
0 - no shivering,  
1 – shivering not interfering with monitoring or causing distress,  
2 - shivering interfering with OR patient monitoring devices (ECG, BP, Pulse 
oximeter) and causing patient distress. 

 
Effect of Warming Mattress on Perioperative Hypothermia Following Cesarean 
Delivery ID:Pro00039382.  3.30.17 
During the temperature monitoring period we will record patient’s vital signs as 
dictated by standard of care: heart rate, noninvasive blood pressure, pulse oximetry 
and episodes of interruption of monitoring secondary to a moving artifact.  Other 
recorded variables will be room temperature, humidity, duration of surgery, 
estimated blood loss, hemoglobin level before surgery and on POD#1. 
 
We will record time of skin-to-skin contact, initiation of breastfeeding, length of 
hospital stay, and incidence of surgical wound infection. Thermal comfort will be 
evaluated at the same time points as temperature, using a visual analog scale, in 
which 0 is the worst imaginable cold, 50 is temperature comfort, and 100 identifies 
the worst imaginable heat. We will ask the patients to provide a satisfaction score 
for the quality of care using a scale 0-100, 0=extremely unsatisfied, 100=extremely 
satisfied. 
 
Neonatal parameters: rectal temperature at delivery and Apgar scores at 1 and 5 
minutes will be recorded as routinely measured by the assigned nurse taking care of 
the neonate in the delivery room.  
 
A review of medical records will be performed to determine the length of hospital 
stay and surgical wound infection rate.  
 
For patients with no data for their postoperative course (outside of the Cedars-Sinai 
electronic medical record system) we will contact them via telephone to inquire 
about postoperative surgical wound infection complications. The call will take place 
30 days after cesarean section was performed. 
 
STATISTICS AND DATA HANDLING: 
 
Using results from a previous published study, power analysis was performed to 
determine the sample size necessary to detect a temperature difference of 0.2 
degree C with power 0.8, a type 1 error 0.05 and standard deviation 0.5 degree C. 
We calculated 50 patients in each group to detect such an effect.  
  
Patients will be randomized in two groups: with or without active warming.  A 
computer generated randomization number will be assigned to each patient, 
patients will not be aware of their group allocation.  
 
Numeric variables: temperature, blood loss, transfusion rate, time to initiate skin to 
skin contact or breastfeeding, patient thermal comfort and satisfaction score and 
length of hospital stay will be compared with a unpaired Student t-test or Mann-
Whitney U-test depending on data distribution. Categorical variables: incidence of 
perioperative hypothermia, shivering, wound infection rate, transfusion rate will be 
compared with chi-square test or Fisher’s exact test.