It is unclear whether routine addition of intra-operative forced-air warming in addition to warmed intravenous fluids during cesarean delivery under spinal anesthesia is beneficial. In this single-center randomized trial, we aim to test the primary null hypothesis that our current protocol of warmed intravenous fluids is similar to a combination of warmed intravenous fluids with intra-operative lower-body forced-air warming to maintain maternal temperature after cesarean delivery under spinal anesthesia.

We also aim to assess the rate of maternal shivering during and after the procedure between the two groups, the maternal thermal comfort score, neonatal Apgar scores and umbilical pH levels. If we demonstrate no clinically important difference between the two interventions, clinicians will be able to continue our current protocol of warmed intravenous fluids only during cesarean delivery.

Primary aim Investigate whether a combination of intra-operative lower-body forced-air warming and warmed IV fluids is superior to our current standard of warmed IV fluids alone in influencing maternal core temperature following spinal anesthesia for cesarean delivery.

Secondary aim

1. To compare mean core temperature on arrival to post-anesthesia care unit (PACU) in women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone
2. To compare incidence of hypothermia among women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone
3. To compare incidence of shivering following recovery in post anesthesia care unit (PACU) in women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone
4. To compare thermal comfort levels for women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone
5. To compare use of meperidine in post anesthesia care unit (PACU) to treat postoperative shivering, in women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone
6. To compare newborn outcomes (rectal temperature at birth, umbilical vein pH & Apgar scores post-delivery) in women who received combination of intra-operative lower-body forced-air warming and warmed IV fluids versus IV fluids alone

Inclusion Criteria:

1. Written informed consent
2. Age between 18-50 years old
3. American Society of Anesthesiologists (ASA) physical status 2-3
4. Gestational age greater than 37 completed weeks
5. Singleton pregnancy
6. Elective cesarean delivery.

Exclusion Criteria:

1. Known allergy to local anesthetics

2. Contraindication for spinal anesthesia

   1. Patient refusal
   2. Bleeding diathesis
   3. Neuropathy

no plan

Postanesthesia care unit nurses assess primary outcome and will not know the group assignment

Sample size was calculated for the primary outcome of difference between the groups in maternal temperature on arrival to the post-anesthesia care unit. We calculated the a priori sample size, WinPepi, based upon a prior publication that compared Active-Warming versus No-Warming, mean(standard deviation) 35.9(0.5)0 C versus 35.5(0.5), power 90%, 0.05 two-sided significance (Cobb et al). For clinical significance we calculated sample size with a mean difference of 0.50 C, with SD 0.5, power 90%, two sided significance with potential for 10% dropouts, total 66 women, 33 per group, and without dropouts, 22 per group total 44 women.