Epidural Positioning During Labor May Affect Outcomes

Epidural Positioning During Labor May Affect Outcomes

New York—A new study examining a potential effect of patient positioning on epidural pressure during labor is raising the question of whether higher epidural pressure is a clinical concern in this context. The study’s authors say anesthesiologists should administer an epidural in a lateral decubitus position during labor because there is less epidural pressure and better uteroplacental perfusion, making it safest for mother and infant.

In contrast, other experts say there is no reason to be concerned with positioning and there is no evidence that epidural pressure affects labor or fetal outcomes.

“Maintaining adequate uteroplacental perfusion in a lateral position, as reflected by lower epidural pressures during an epidural block, can protect against maternal hypotension and minimize the potential for maternal and neonatal morbidity, and our study shows that a lateral decubitus position is safe for both the mother and fetus,” said lead researcher Shaul Cohen, MD, the director of obstetric anesthesia at Rutgers-Robert Wood Johnson Medical School, in New Brunswick, N.J.

Dr. Cohen reached this conclusion after he and his colleagues retrospectively reviewed medical records from 100 women who gave birth at their institution and received epidural analgesia in the sitting position, compared with 80 women who were administered epidural analgesia in the lateral position.

The investigators analyzed fetal distress and maternal hypotension to determine if there was a relationship between epidural pressure, positioning and those two outcomes.

Dr. Cohen’s gravity-based technique involves connecting a syringe with IV extension tubing filled with 20 mL of 0.1% ropivacaine, 1 mcg/mL of sufentanil and 2 mcg/ml of epinephrine attached to the epidural needle, which is positioned in the epidural space. “We assumed that the epidural pressure correlated to the length of the fluid column just before it started to flow into the epidural space, while fluid levels fluctuated along with maternal heart rates and respirations.” Dr. Cohen explained that a higher column of fluid in the IV tubing indicated greater epidural pressure.

In a presentation at the 72nd Annual Postgraduate Assembly in Anesthesiology (abstract P-9074), Dr. Cohen’s team reported that average epidural pressure was higher in women administered anesthetic in the sitting position than the lateral decubitus position. For patients giving birth for the first time, for example, the height of the fluid column in the sitting position was 38.81 (±1.67) cm H2O, compared with 18.9 (±0.88) cm H2O in the lateral position (P<0.0001). Epidural pressures were similarly higher in women who had given birth previously and were administered an epidural in the sitting position

Higher epidural pressures in the sitting position indicate the uterus may be partially occluding the vena cava, thus potentially reducing uteroplacental perfusion and compromising fetal well-being as well as increasing the risk for hypotension, Dr. Cohen noted. Although there were no signs of either outcome during the first hour of the epidural block in either group, he believed this was a reflection of the healthy population of patients and fetuses in the study, and that outcomes could have differed if patients with higher-risk pregnancies were included.

“Healthy mothers and healthy babies can tolerate this reduction in uteroplacental perfusion, but women with diabetes, severe preeclampsia, and those who have early separation of the placenta—which can be silent and not immediately diagnosed—already have preexisting compromised uteroplacental perfusion, so further reducing uteroplacental perfusion places them and their fetuses at greater risk of poor outcomes,” he said.

As evidence that positioning matters, Dr. Cohen cited an earlier publication that reported a 20% rate of vasovagal reflexes in women administered an epidural in the sitting position during labor (Int J Obstet Anesth 2008;17[2]:146-149).

However, not everyone was convinced. Neither that study nor Dr. Cohen’s research convinced Stephen Halpern, MD, an obstetric anesthesiologist and a professor of anesthesia at the University of Toronto Faculty of Medicine, that epidural anesthetic is safer to administer in the lateral position. According to Dr. Halpern, a major weakness of Dr. Cohen’s study is that his team did not objectively measure fetal harm to support their assertion that fetal well-being can be affected by epidural pressure. In view of that gap and what he said was a lack of data indicating that epidural pressure is related to negative birth outcomes, Dr. Halpern said he won’t be changing his practice.

“During labor and during life, pregnant women assume all sorts of positions for various periods of time,” said Dr. Halpern. “I would continue to use the body position that is most efficient and comfortable for the patient.”

—David Wild