Active Warming Versus Non Active Warming During Caesarean Section for Preventing Neonatal Hypothermia
Condition: Neonatal Hypothermia
MeSH terms: Hypothermia
Study type: Interventional

Summary: 
      Peri-operative warming is well established for general operations, but there is limited
      literature on the active warming of pregnant women undergoing caesarean section (CS).
      Specifically, there is a lack of evidence on the effect, if any, of actively warming mothers
      on the new-born's temperature and general wellbeing. The two active warming methods
      recommended by NICE are the use of forced-air warming and fluid warmers.

      Women's temperature tends to fall below the normal level (36.0oC to 37.5oC) during caesarean
      section if they have not been actively warmed during their operation (peri-operative).
      Peri-operative hypothermia may increase the morbidities experienced by women after caesarean
      section. While shivering is the most common postoperative incident, hypothermia may delay
      wound healing or increase the risk of wound infection, and can increase the risk of
      haemorrhage.

      Neonatal hypothermia has a direct effect on the baby's cardiopulmonary, vascular system and
      central nervous system and increases the risks of mortality and morbidity. Specifically,
      neonatal hypothermia can lead to respiratory difficulties and apnoea, hypoxemia, carbon
      dioxide retention, metabolic acidosis, hypoglycaemia and decreased oxygen delivery to the
      tissues.

      The absence of research and evidence on the effects of actively warming women undergoing
      caesarean section at term gestation on the temperature of new-borns during SSC means that
      further research is required.
    

Detailed description: 
      Peri-operative active warming is the practice of warming patients who undergo an operation
      with the use of one or more warming devices. Active warming can be initiated before, during
      and/or after an operation and its main purpose is to prevent and/or manage hypothermia in
      patients. Commonly used warming devices include: forced-air warming, fluid warmers, heating
      gel pads, water mattresses and electric blankets.

      Peri-operative active warming has been researched over the past 30 years, with more
      sophisticated methods of active warming being introduced in recent years. Regardless of their
      complexity, these devices are used in order to prevent inadvertent perioperative hypothermia
      (IPH) and its complications in patients who undergo an operation. Complications of IPH
      include: thermal discomfort (including shivering), increased intra-operative blood loss,
      increased risk of wound infection, cardiac morbid events and increased length of stay in
      recovery room and in the hospital.

      Although peri-operative warming is well established for general operations, there is a dearth
      of literature regarding active warming of pregnant women undergoing caesarean section (CS).
      The National Institute of Health and Care Excellence (NICE) developed guidelines for managing
      IPH for adults undertaking various general operations, however pregnant women and
      children/infants were excluded from these guidelines due to lack of evidence supporting or
      rejecting the use of peri-operative active warming for this population. The two active
      warming methods recommended by NICE include the use of forced-air warming and fluid warmers.
      Specifically all patients should be actively warmed with a forced-air warming device
      before/during their operation if their temperature is below 36°C and every patient should
      receive warmed IV fluids (via an IV fluid warmer) for volumes ≥500 mls of IV fluids. The
      patient's temperatures should be measured every 30 minutes from the time of their anaesthesia
      until their discharge to the ward.

      An additional factor that complicates the decision of applying, or not, an active warming to
      pregnant women during a CS is the effect of active warming on new-borns during/after birth.
      This factor becomes even more relevant when skin-to-skin contact (SSC), between mothers and
      their new-borns, is initiated immediately after a CS. Specifically, there is a lack of
      research evidence on the effect, if any, of active warming on the new-born's temperature and
      general wellbeing. Three unpublished audits undertaken in the theatre department of a large
      maternity hospital in Dublin (between 2012 and 2014), have shown an increased number of
      hypothermic mothers and new-borns during and after CS. The hospital has a general practice of
      not actively warming pregnant women before/during their CS, and women at low risk for
      complications, usually perform SSC with their infants within minutes of birth. The more
      recent of these three audits (2014) showed that 86% (n=33) of women became hypothermic
      peri-operatively (defined as a core temperature below 36°C, while 35% (n=14) of the new-borns
      became mildly hypothermic after birth (defined as a core temperature below 36.5°C, after
      undergoing SSC, despite complying with the hospital guidelines.

      SSC is a widely researched technique, in which a naked new-born (wearing only a nappy and a
      hat) is positioned on its mother's bare chest, covered with warm towels and a blanket. SSC
      has multiple advantages for both mothers and their new-borns. SSC is a usual practice within
      Rotunda Hospital, for babies born either vaginally or via CS. Although this technique is well
      established after vaginal birth, there is a great demand and attempts to establish it in
      mother-infant dyads after birth by a CS. A potential concern arising from this practice,
      however, is that new-borns, born by a CS, are more prone to losing their temperature and
      become hypothermic after a CS, compared with those born via normal birth. A risk factor is
      that if the mothers core temperature drops during the CS, leading to an even lower skin
      temperature, then the risk of a drop in the temperature of the new-born (via conduction) is
      increased by placing the naked baby for SSC on a mother whose temperature is suboptimal.

      When either the mother or the new-born become hypothermic after a CS, there is a higher
      chance that both will be separated in order to be heated, often in different rooms. When this
      separation takes place, SSC is interrupted, early breastfeeding is delayed and the stress
      levels of the mother will increase as she would be concerned about her new-born's wellbeing.
      Additionally, babies who become hypothermic once, or have reoccurring cases of hypothermia,
      after birth are more likely to have invasive procedures such as blood sugar monitoring,
      rectal temperature measurements and blood checks for microbiological investigation and
      prophylactic administration of IV antibiotics (as per hospital's guidelines). These invasive
      procedures could be prevented especially in low risk babies (i.e. term babies with weight
      within the normal limits, or babies whose mothers are not diabetic) by keeping them warm and
      providing early feeding and SSC.

      These obstacles could potentially be eliminated with the use of peri-operative active
      warming. The effects of peri-operative active warming in pregnant women remains inadequately
      researched, with even fewer studies evaluating the effects of peri-operative active warming
      on new-borns who are having SSC.
    

Intervention name(s): active warming
Intervention type(s): Procedure
Intervention description(s): Women randomised to the intervention group will be administrated warm IV fluids (39°C) consisting of Hartman's solution with the use of the theatre's Hotline™ device. The Hotline™ device is set to 39°C in which the Hartman's solution bags will be infused to the women peri-operatively.
Allocation: Randomized
Intervention model: Parallel Assignment
Masking: Single (Participant)
Primary purpose: Prevention
Keywords: caesarean section; neonatal hypothermia; maternal hypothermia; active warming; skin-to-skin contact