CHOICE OF LABOR ANALGESIA AND MATERNAL STRESS RESPONSE
Abstract Number: 95
Abstract Type: Original Research
Introduction: Pain perception involves immuno-neuro-humoral, sensory, emotional, behavioral, and environmental factors (1). Most women rate pain of childbirth as the most painful experience of their lives. Factors affecting the decision by the laboring woman to first, request labor analgesia (LA) and second, to select a specific LA technique [e.g., epidural analgesia (EA) vs. parenteral meperidine (PM) administration] have not been clearly defined (2). The purpose of this prospective observational study was to determine possible associations between maternal stress response in labor and maternal request for LA and selection of a specific LA technique.
Methods: Sixty five healthy, term, nulliparous women in spontaneous labor (mean cervical dilation = 4 cm) who requested labor analgesia between 08:00 and 14:00 were assigned to either EA (N=30) or PM (N=35) group. Intensity of labor pain was assessed before iduction of LA using a 100 mm visual analogue scale (VAS). Spielberger-State-Trait-Anxiety Inventory (STAI) was used to identify sources of stress and to evaluate anxiety levels among laboring women. Maternal tympanic temperature, noninvasive blood pressure, heart rate, and peripheral blood "stress hormones" [epinephrine, norepinephrine, cortisol] and C-reactive protein (CRP)] levels were measured before induction of LA. Nonparametric (Mann-Whitney U-Test) statistical data analysis was conducted.
Results: No demographic differences were noted among the two groups. Parturients requesting EA presented with higher VAS pain scores, and higher blood concentrations of epinephrine and CRP (Table 1.). There was a positive correlation between STAI scores and blood epinephrine concentrations in EA group (rho=0.43, p=0.03). In PM group there was a positive correlation of STAI scores with blood CRP levels (rho=0.46, p=0.04). VAS pain intensity correlated with blood cortisol levels in PM group only (rho=0.64, p=0.00).
Discussion: Perception of pain, including pain of uterine contractions, is a complex process that involves interaction of both central and peripheral mechanisms (1). Stressful experience during childbirth evokes generalized neuroendocrinal response producing widespread physiological effects during labor. This stress responce may influence maternal choice of a specific LA technique.
Table 1: Stress variables in parturients requesting epidural analgesia. Median (min-max)
Conclusion: : Mothers requesting EA may present with altered stress characteristics as compared to other parturients. These results require validation by further multicenter studies.
1. Acta Obstet Gynecol Scand 2004; 83: 415-424.
2. Anaesthesia 2009, 64: 856-862.