Medical Transfer of Patients in Preterm Labor: Treatments and Tocolytics

Abstract Objective. To examine the epidemiology, effectiveness, and safety of tocolytics, and the variation in use of standard treatments and predictive testing for women in preterm labor (PTL) transported to tertiary care. Methods. This was a health record review of consecutive PTL patients (<38 weeks gestation) transported to a tertiary care facility by Ontario's air and land critical care transport service between January 1, 2006 and January 1, 2011. The primary outcome was the effectiveness of tocolytics in decreasing the frequency of contractions and incidence of delivery. Secondary outcomes included the type of tocolytics used, adverse events (defined a priori), use of standard treatments (corticosteroid, antibiotic), and use of predictive tests (cervical length measurement, fetal fibronectin). We report descriptive statistics and relative risk of contractions decreasing with tocolytics with 95% confidence intervals. Results. Of the 510 transports reviewed, 488 met all inclusion criteria with the following characteristics: mean age 26.1 years, mean gestational age 31.2 weeks, mean transport time 80 minutes, 61.0% multiparous, 13.3% twins, mean initial dilatation 1.8 cm, contraction <8 min apart 67.7%, and 66.8% from Northern Ontario. Tocolytics were used in 206 (42.2%), with nonsteroidal anti-inflammatory drugs and nitroglycerine being used most frequently. Eleven (2.3%) patients delivered during transport, 4 (36.4%) of which received tocolytics with relative risk (RR) 0.8 (95%CI 0-2.0), and number needed to treat (NNT) 165 (31.5-299.3). Among the 311 (63.7%) patients for which change in contractions was documented, 140 (45%) received tocolytics and of these patients, contractions decreased in 94 (67%), with an RR 0.6 (95%CI 0.3-0.9) and NNT 4.6 (3.1-6.2). Adverse events were documented in 67 (14%) patients (most commonly tachycardia 5.8%). Steroids were appropriately used in 268 (54.9%) patients and antibiotics were appropriately used in 286 (58.6%) patients. Predictive testing was performed in only 19 (3.9%) patients. Conclusions. Tocolytics were associated with decreased contraction frequency in more than two-thirds of those treated. However, nearly half those who did not receive the treatment also had decreased contractions, and the effect did not reach statistical significance. Variation in the type of tocolytic drug used suggests a need for clinical practice guidelines for tocolytic use during transport of PTL patients.