Postoperative Hypothermia Control In Older Patients With Total Knee Arthroplasty: Effect Of Electric And Woolen Blanket
Condition: Arthroplasty, Replacement, Knee
MeSH terms: Hypothermia
Study type: Interventional

Summary: 
      The purpose of this studywas to assess as experimental whether if electric blanket together
      withwoolen blanketwere effective in the postoperative period at patients with TKA. The
      population of the studywas the TKA patients operated at Kastamonu State Hospital (N=209); the
      sample with quota sampling was a total of 46 patients, including 23 selected 23 control
      group. Data collection forms for data collection, tympanic thermometer, saturation meter,
      sphygmomanometer, woolen blankets and electric blankets were used in research process.The
      data collected in this study were analyzed using SPSS 16.0 software. To analyze the data;
      descriptive statistics, Kolmogorov-Smirnov, X2, Student's t, Mann-Whitney U test,
      Kruskal-Wallis analysis of variance ANOVA and linear regression analysis were used. According
      to the results; it was determined that the use of electric blankets together with woolen
      blankets was an efficient method of warming for TKA patients and unheated woolen blanketsare
      not sufficient to improve body temperature postoperatively. Studying with large samples and
      assessing the effectiveness of warmed woolen blankets with determining the number of warmed
      woolen blanket for enhancing the control of hypothermia is suggested.
    

Detailed description: 
      Methods 2.1. Study Design and Setting As a parallel group, randomized controlled trial with
      repeated measures to test the following hypothesis: the average body temperature of patients
      who use an electric blanket along with a woolen blanket reaches a normal value at least one
      timeframe (15 minutes) before that of patients who use a woolen blanket. It was used electric
      blankets for the patients in the experimental group in addition to the routine practices in
      the clinic and did the routine practice in the clinic for the patients in the control group
      by the researcher.

      The study was conducted in the orthopaedic clinic of a public hospital in Turkey with the
      capacity to serve 100.000 patients, where approximately 250 TKA operations are performed per
      year.

      2.2. Sample Sample of the study included patients who had TKA under spinal and/or epidural
      anesthesia. Sample size calculation was performed using the Number Cruncher Statistical
      System (NCSS)-Power Analysis and Sample Size (PASS) software. Based on the differences in the
      mean scores of body temperatures for seven different times (before surgery, taking to their
      beds after surgery, 15th minutes, 30th minutes, 45th minutes, 60th minutes and 75th minutes
      after surgery) obtained from the patients in the pilot study, the alpha level was set at 0.05
      and power as 80%. Thus, 23 patients were included in each group (23 patients in the
      experimental group and 23 patients in the control group). The patients were selected
      according to age and gender (each group: male: 4, female: 9 between 60- 69 ages; male: 3,
      female: 7 between 70-79 ages) and were randomized according to days of the week.

      2.3. Participants and Procedure The inclusion criteria for this study were: being between the
      ages of 60 to 79, having an SPO2 value above 90% when they were hospitalized, no having
      diseases affecting cognitive functions or thermoregulation due to systemic effects, and no
      using any medication which could effect thermoregulation. Additionally, new patients were
      selected for the sample in place of patients who wished to withdraw from the study since they
      felt uncomfortable by the way the blanket was placed on them or were uncomfortable being
      uncovered above their wrists or ankles or lower than the bottom line of the clavicle, or who
      needed to remove the blanket completely because of the clinical interventions, or who had to
      be taken to the intensive care unit due to the unexpected changes in their general condition.
      Four different surgical teams and one single anesthesia team were performed the TKA surgeries
      in this hospital. The anesthesia team administered the same anesthetic medication as a spinal
      or local combined (spinal and epidural) to all patients in the sample.

      The study was conducted between November 1, 2013, and May 1, 2014. The researcher (ED)
      informed the nurses in the clinic about the procedures to be done for the experimental and
      control groups. The day before the application of this study, the researcher reviewed the
      list of the operations to be performed the next day and identified patients who would have
      TKA. The researcher also evaluated the fitness of these patients to sample criteria and
      patients were informed both verbally and in written form. After obtaining informed consent,
      it was measured patients' height and weight, recorded their demographic data, family history,
      medical history and the taking medication on a descriptive characteristics information form
      (DCIF) by the researcher. The researcher measured the patients' body temperatures in the same
      ear in which their body temperatures were measured when they had been hospitalized. The
      researcher evaluated whether there were earpieces, infections or external auditory canals for
      plugs in deciding in which ear to measure the body temperature. To measure the pulse,
      arterial blood pressure and SPO2, it was used the arm that did not have established vascular
      access. It was obtained the temperature and humidity of the operating room one hour after
      each patient was taken to surgery and recorded this information on the DCIF.

      In addition, a woollen blanket used in the clinic was laid on the bed while control group
      patients were in the operating room. For experimental group patients, an electric blanket was
      placed under the mattress and a wool blanket on the bed sheet while they were in the
      operating room. The electric blanket was operated at "hot" level for 20 minutes before the
      experimental patient left the operation room.

      After the patients were taken to their own beds after surgery, the researcher covered them
      with a wool blanket from the top of clavicle to the bottom of their feet, put the
      sphygmomanometer on the arm without an IV line, positioned the sphygmomanometer so that the
      instrument panel was on the blanket and measured the patients' blood pressure. Then, the
      electric blanket was operated at the "warm" level for the experimental group, and it was
      turned off and unplugged when their body temperature reached 36.0 °C.

      After each measuring of vital signs, it was recorded the responses "very little", "a little"
      and "very much" as "Yes", and the responses "no" and "no, I don't" as "No" by asking whether
      they felt cold or not. The researcher put the SPO2 probe on the patients' fingers after blood
      pressure measurements and counted respiratory rates for one minute while waiting for the SPO2
      measurements. During the SPO2 measurement, it was noted if patients did not move, did not
      have nail polish, henna or any other paint on their finger on which the measurement was made,
      whether the pigmentation of the skin was not different from other body sites, and whether the
      measurement site was not colder than other body sites19. To prevent light in the room from
      affecting the measurement, the woolen blanket was placed on the patients' hands in a way so
      as not to prevent reading the measurement value after the saturation probe was placed on the
      finger. The patients' body temperatures were measured in the ear recorded on the DCIF. The
      ear was pulled back and entered at a right angle. After this measurement, the researcher
      evaluated shivering by observation, and recorded these data on the DCIF.

      Finally, it was read the temperature and humidity in the room on a thermohygrometer and
      recorded the measurement on the evaluation form by the researcher. The researcher measured
      body temperature, pulse rate, respiration rate, arterial blood pressure, pulse pressure,
      oxygen saturation, feeling cold and shivering of experimental and control group before their
      surgeries, every 15 minutes after surgeries until being 36 0C of body temperature.

      2.4. Measurements To collect the data, a descriptive characteristics information form was
      used, which was developed in accordance with the literature (Lundgren et al., 2011, O'Malley
      et al., 2012, Pulido et al., 2008). Tools included a tympanic thermometer (Kendall),
      saturation measurement device (pulse oximeter), sphygmomanometer (Omron), woolen blanket and
      electric blanket.

      2.5. Analysis The descriptive statistics of the study are presented as means, standard
      deviations and frequency and percentages. The presence of a normal distribution was
      determined by the Kolmogorov-Smirnov test. Data was evaluated as using the chi-square test to
      compare categorical data in contingency tables, the Student's t test for normally distributed
      variables in comparing differences between the groups, the Mann-Whitney-U test for variables
      not normally distributed, one-way ANOVA for normally distributed variables in the comparison
      of more than two groups and Kruskal-Wallis analysis of variance when the variable was not
      normally distributed.

      2.6 Ethical approval This study was approved by a University's Clinical Research Ethics
      Committee (10/10/2013-16969557-964) in Ankara and, it was obtained permission by Public
      Hospitals Association General Secretariat (24/09/2013-91379769/13690). Informed consent was
      provided by all participants. All study procedures were conducted in accordance with the
      Declaration of Helsinki.
    

Intervention name(s): electric blanket
Intervention type(s): Device
Intervention description(s): After the patients were taken to their own beds after surgery, the researcher covered them with a wool blanket from the top of clavicle to the bottom of their feet, put the sphygmomanometer on the arm without an IV line, positioned the sphygmomanometer so that the instrument panel was on the blanket and measured the patients' blood pressure. Then, the electric blanket was operated at the "warm" level for the experimental group, and it was turned off and unplugged when their body temperature reached 36.0 °C.
Allocation: Randomized
Intervention model: Parallel Assignment
Intervention model description: As a parallel group, randomized controlled trial with repeated measures to test the following hypothesis: the average body temperature of patients who use an electric blanket along with a woolen blanket reaches a normal value at least one timeframe (15 minutes) before that of patients who use a woolen blanket. It was used electric blankets for the patients in the experimental group in addition to the routine practices in the clinic and did the routine practice in the clinic for the patients in the control group by the researcher.
Masking: None (Open Label)
Primary purpose: Supportive Care
Keywords: Hypothermia; Postoperative period; Woolen blanket; Electric blanket; older people.