OBJECTIVE
To search for risk factors of hyperthermia development associated with anesthesia of labor by epidural analgesia (EA), to evaluate the role of systemic inflammatory process in the genesis of such hyperthermia.
MATERIAL AND METHODS
The prospective study included 150 females whose deliveries took place in the maternity hospital F.I. Inozemtsev State Clinical Hospital (Moscow) in the period from October 1, 2022 to May 4, 2023. The main group consisted of 100 women in labor anesthetized by EA for pain syndrome (7 points or more on the visual analog scale), the control group included 50 patients in whom labor was carried out without neuroaxial anesthesia. The study analyzed body temperature (T) elevation of different degrees: tendency to hyperthermia — T ≥37.0<37.5 °C; hyperthermia — T ≥37.5<38 °C; fever — T ≥38 °C, as well as the type of delivery: vaginal delivery and cesarean section. Patients with EA delivery and T <37.5 °C (49 out of 100) constituted subgroup a, with T ≥37.5 °C (51 out of 100) — subgroup b. Comparative analysis of anamnestic data, single-factor correlation and dispersion analyses were performed in these subgroups to find the factors predisposing to exceeding the normative T values in laboring women.
RESULTS
The analysis showed statistically significant association of anesthesia of labor by EA with the development of hyperthermia: in the main group hyperthermia was registered in 51 (subgroup b) women in labor (51%; 95% confidence interval — CI 41.78—60.17%), in the control group — in only 3 (6%; 95% CI 2.2—13.71%), the differences were statistically significant (p<0.001). The predisposing factors for the development of EA-associated hyperthermia were the duration of labor, namely the first period (p=0.003) and anhydrous interval (p<0.001), duration of anesthetic exposure (p=0.005), number of vaginal examinations (p=0.001), and oxytocin labor stimulation (p=0.007). Under analgesia conditions, hyperthermia was recorded almost 5 times less frequently when the opening of the cervix was 5 cm or more than when anesthesia was administered from the onset of labor to the opening of the cervix less than 5 cm (17.65 and 82.36%, respectively). In addition, a positive correlation of medium strength was found between the increase in laboring women’s body T ≥37.5 °C and the serum level of the most active pyrogen, the proinflammatory cytokine IL-6 (correlation coefficient 0.411; p<0.001). Thus, it can be assumed that the main pathophysiological mechanism of hyperthermia development in EA is the increased production of proinflammatory pyrogenic cytokines in response to anesthetic administration (in this case ropivacaine), in connection with which the duration of the latter administration becomes crucial.
CONCLUSION
Early (in the latent phase of labor) and prolonged EA are associated with an increased risk of hyperthermia. Optimization of the methodology of labor analgesia will improve the quality of obstetric care.
