Medical Acupuncture
A Journal For Physicians By Physicians

Published by
The American Academy of
Medical Acupuncture

Fall / Winter 1998 / 1999 - Volume 10 / Number 2
"Aurum Nostrum Non Est Aurum Vulgi"

SALIVARY CORTISOL AS AN INDICATOR OF STRESS IN PREMATURE INFANTS: THE EFFECT OF ELECTRIC STIMULATION OF ACUPUNCTURE MERIDIANS IN BLUNTING THIS RESPONSE

By Lynnae Schwartz, M.D.,* Washington, DC, Howard Bauchner, M.D., Richard Blocleer, M.D., Katherine Jorgensen, BSN, Colleen Pearson, Regina O'Donnella, Merle Mirochniclc, M.D.

ABSTRACT
     Background
     Ophthalmologic examination for retinopathy of prematurity (ROP) is a stressful procedure required as standard care for premature neonates. Pharmacologic options to reduce stress and pain during ROP exam are limited. The use of transcutaneous electrical stimulation of acupuncture meridians to reduce stress during ROP examination has not been previously investigated.
     Objective
     To confirm preliminary data showing salivary cortisol to be an immediate stress marker in premature infants; to determine if electrical stimulation of acupuncture meridians blunts the rise in salivary cortisol associated with ROP examination.
     Design
     Randomized, single-blind, controlled pilot study, ongoing between January, 1995 and August, 1996.
     Participants
     Prematurely born infants requiring ophthalmologic examination for ROP.
     Main Outcome Measure
     Salivary cortisol levels measured by radioimmunoassay (RIA) at baseline; compared to post-ROP examination concentrations.
     Results
     Thirteen infants were studied (three crossed over), resulting in 16 paired saliva samples. Treatment and control infants were comparable; no adverse effects were observed. Salivary cortisol concentration increased in both groups; the change was statistically significant only in control infants (P=0.0272). Comparison of change in salivary cortisol between control and treatment infants suggests trend towards blunted stress response in treatment infants (P=0.0592). A minimum N of 192 paired samples will be needed to show statistical significance, assuming continuation of the observed trends.
     Conclusions
     Salivary cortisol rises, with ROP examination. Electrical stimulation appears to blunt this stress response. A larger study is needed to determine significance and delineate the optimal characteristics of the electrical stimulation applied.

KEYWORDS
     Acupuncture, Electroacupuncture, Premature Infants, Cortisol, Salivary, Electrical Stimulation, Retinopathy of Prematurity (ROP)

INTRODUCTION
     Routine care for prematurely born infants in the Neonatal Intensive Care Unit NICU (Children's National Medical Center, Washington, DC) typically requires many intrusive, stressful procedures, including venipuncture, diagnostic procedures, and multiple therapeutic interventions. Even routine care may be stressful (1,2). In addition, the NICU environment itself can be harsh, despite efforts to reduce noise, bright lights, unnecessary handling, and random interruptions of rest.
     Ophthalmologic examination for retinopathy of prematurity (ROP) may be a particularly noxious event; it requires immobilization, handling by at least one additional care provider, administration of dilating eye medications, insertion of retractors, extremely bright light directed to all areas of the retina, and prolonged time, especially in the teaching environment. Potentially significant physiologic instability may follow (3), consistent with cardiovascular, respiratory, autonomic, and metabolic responses known to occur in neonates subject to pain and stress (4).
     Although assessment of pain and stress in premature infants in the NICU is primarily observational (5), the hypothalamic-pituitary-adrenocortical (HPA) system is reactive in even the most premature of viable infants (6,7), releasing cortisol from the adrenal cortex in response to multiple endogenous and exogenous stimuli. Plasma and salivary cortisol levels provide a physiological marker of HPA activity, especially stress, with plasma concentrations peaking within 20-30 minutes after the onset of noxious stimulation (8), followed by a parallel rise in salivary cortisol reflecting unbound (active) cortisol levels in the Serum (9). Salivary cortisol assays, therefore, allow noninvasive determination of HP.A activity and stress response in adults (10,11), and infants (12).
     Environmental efforts to decrease stress are routine in NICU care, but not always sufficient. Pharmacologic stress reduction and/or analgesic interventions may be added, but options are limited in situations such as ROP examination, where the risk of respiratory and cardiovascular depression requiring invasive support far outweighs potential benefit.
     Electroacupuncture has been shown to be analgesic in multiple small animal models (13,14), and in humans undergoing surgical procedures (15), raising the possibility that electrical stimulation of acupuncture points might also be analgesic and/or have a stress reducing effect in infants.
     Our investigation had two objectives: the first, to confirm preliminary data showing salivary cortisol response to be an immediate marker of stress in premature infants; secondly, to determine if electrical stimulation of acupuncture meridians could blunt the stress response provoked by ROP examination, without apparent adverse effects. We hypothesized that salivary cortisol levels would rise significantly with ROP examination, and that noninvasive electrical stimulation of acupuncture points would safely blunt this physiologic index of pain and stress in premature infants.

METHODS
     With Institutional Review Board approval, and written, informed parental consent, premature NICU infants were recruited between January, 1995 through August, 1996, into this randomized, singleblind, controlled study to receive true (current on) or sham (current off) transcutaneously applied electrical stimulation of acupuncture meridians during ROP examination. Approximately 85% of parents asked consented to their infant's participation.
     Oral feeds were stopped two hours prior to study. All investigators, laboratory personnel, and observers were blinded, except for the one technician applying electrodes and treatment. No infant was studied more than two times, regardless of the total number of sequential ROP examinations performed. Treatment versus sham electrical stimulation crossed over for infants studied twice.
     Demographic data was collected for all subjects including birth weight, post-conception age at time of delivery and at time of study, gender, twin status, level of supportive care, significant medical problems, prenatal exposure to illicit drugs, current medications, and level of physiologic stability prior to and during study. Duration of ROP examination was noted, as were all potential adverse events during the following 24 hours.
     An ITO-F3 electroacupuncture unit, with lead wires to four electromagnetic electrodes (3000 gauss/electrode) applied to paired points on the hands (Hegu) and feet (Taichong), delivered 1.3 Hz constant current at the lowest possible intensity to treatment infants. Saliva was obtained by gentle aspiration of the oral cavity prior to electrode placement, and again at 15 minutes after completion of ROP examination. Electrical stimulation of treatment infants was discontinued upon completion of ROP examination. All electrodes were removed after collection of the second saliva sample.
     Saliva samples were coded and stored at -80 degree C pending analysis. Pre- and post-examination salivary cortisol levels were determined by radioimmunoassay (Diagnostic Products Corporation, Los Angeles, California), reported as ugms/dl. Results reported as below detectable limits of the assay were recorded as 0.05 ugms/dl.
     Data was analyzed using BMDP statistical software (Los Angeles, California). Differences were evaluated pre-to-post ROP exam within each study group by using paired t-tests. Between groups, comparison was performed using the Student's t-test and Mann-Whitney rank-sums non-parametric analysis. Data for the three crossover patients was included only once for between-group comparisons; treatment (current on) pre and post-cortisol values were used in this analysis. Statistical significance was determined with critical alpha at 0.05. Preliminary data was then used to estimate future sample size sufficient to show statistically significant difference (within the realm of clinical relevance), assuming maintenance of current trends and normalized distributions.

RESULTS
     Twenty-two infants were enrolled; all were not ultimately examined prior to discharge. One patient died prior to ROP examination. Efforts to obtain sufficient quantities of saliva were unsuccessful in five instances. Paired saliva samples were available for 13 patients; three infants were studied twice in a crossover manner, resulting in 16 total study events. Treatment and control infants were comparable (Table 1). No statistically significant differences were found between treatment and control infants with respect to all demographic factors assessed, including race, gender, twin status, birth weight, post-conception age at birth and time of study, general level of NICU support, prenatal drug exposure, including cocaine, important medical problems, medications, and physiologic stability. No adverse effects were observed in either group.
     As shown in Table 2, salivary cortisol concentration increased following ROI> exam in both groups, although the change was statistically significant only in control infants (P=0.0272). Comparison of the change in salivary cortisol between control and treatment infants suggests a trend towards blunting the salivary cortisol stress response in infants receiving electrical stimulation (P=0.0592). A minimum N of 192 paired samples would be needed to show statistical significance, assuming continuation of the observed trends.

DISCUSSION
     The potential negative effects of pain and stress in premature infants have been widely appreciated, prompting significant changes in the NICU environment, as well as in sedation, analgesic, and anesthetic management for this vulnerable population. There are, however, situations such as ROP examination, where the risks of systemic sedation and/or

analgesia appear to outweigh the risk of procedure. Unfortunately, topical anesthesia appears not to blunt the physiologic instability associated with ROP examination (3).
     Seeking an additional approach to patient comfort under these circumstances, we investigated the potential safety and efficacy of noninvasively delivered electrical stimulation of acupuncture points and meridians in premature infants undergoing ROP examination, using salivary cortisol as an immediate marker of stress response. Our data suggests that premature infants respond to ophthalmologic examination with a significant increase in salivary cortisol, reflecting an increase in HPA activity. Although the sample size was too small to assess efficacy, the data trended toward blunting the rise in salivary cortisol provoked by ROP exam stress. Electrical stimulation appeared to have been well tolerated in this small study population.

     This is the first report, to our knowledge, of electrical stimulation of acupuncture meridians to relieve pain and stress in infants. There is, however, substantial literature describing electroacupuncture in small non-primates, showing increased endorphin, mct-enkephalin and serotonin concentrations in blood and cerebral spinal fluid (CSF) after electrical stimulation of acupuncture points (16, 17), raising the possibility of similar effect in humans.
     The analgesic effects of electrical stimulation of acupuncture points may be a function of the frequency of electrical stimulation (16). Different receptors appear to be stimulated by different currents, with low frequencies between 2 and 15 Hz activating endorphin pathways (18), while higher frequencies lead to the release of norepinephrine and/or serotonin without analgesia (19). For this reason and out of concern for our patients' comfort, we used the lowest possible frequency (1.3 Hz) and intensity delivered by the ITO F-3 electroacupuncture unit.
     Our point selection wa.s based upon Traditional Chinese Medical (TCM) theory. TCM is derived from Buddhist, Taoist, and more ancient Chinese philosophy (20), modified over at least 2,000 years by experience and observation, without reliance upon scientific methodology. To briefly summarize, TCM postulates that there exists a form of universal energy, Qi, flowing throughout the body in channels, i.e. meridians (21). Hegu and Taichong are Source points, said to contain Qi with the infant's first breath (22). Both are used clinically to treat eye diseases, and provide acupuncture anesthesia for eye surgery.
     Our study was limited by its small sample size of 13 infants, with only 3 crossed over to both conditions, resulting in limited power to detect statistical difference in cortisol response between the two groups. In the interest of safety, only the lowest possible frequency and intensity of electrical stimulation was applied. Possibly, more intense stimulation would result in larger differences between control and treatment infants, or, conversely, have the opposite effect. In addition, although no apparent adverse effects were observed, given the small number of patients studied under limited conditions, our data does not allow the generalization that electrical stimulation of acupuncture meridians is safe in all infants under more varied circumstances. Lastly, our primary outcome indicator was salivary cortisol response. Additional physiologic and behavioral measures of pain and stress were not concurrently assessed, limiting our ability to correlate cortisol response with other established indicators of neonatal comfort and stability.
     In conclusion, this pilot data demonstrates that salivary cortisol is a useful marker of stress response to ROP examination in premature infants. Electrical stimulation of acupuncture points was easily applied without apparent toxicity. A much larger study is necessary to determine if electrical stimulation of acupuncture meridians is effective in significantly reducing this stress response, and if so, to delineate the optimal characteristics of the electrical stimulation applied. (Presented in part at the Pediatric Anesthesiology Meeting, Feb. 1215, 1998, Phoenix, Arizona.)

ACKNOWLEDGEMENT
     The authors wish to thank Ms. Eileen McNamara for her excellent technical support in determination of salivary cortisol levels, and Dr. Jill Josephs for her thoughtful comments during manuscript preparation.

REFERENCES
1. Speidel BD. Adverse effects of routine procedures on preterm infants. Lancet 1978; 1 (8069):864-866.
2. Long JG, Philip AGS, Lucey JF. Excessive handling as a cause of hypoxemia. Pediatrics 1980; 65(2):203-207.
3. Porter FL, Lueder G. Anesthetized retinopathy of prematurity examinations elicit significant physiologic instability in premature infants. Pediatric Research 1997; 41 (4): 170A.
4. Anand KJS, Hickey PR. Pain and its effects in the human neonate and fetus. NEJM 1987; 317(21):1321-1329.
5. Porter F. Pain assessment in children: infants. In: Schecter NL, Berde CB, Yaster M, eds. Pain in Infants, Children and Adolescents. Baltimore, MD, Williams and Wilkins 1993; 87-96.
6. Forsyth, CC. The growth and development of the endocrine glands - adrenal cortex. In: Davis JA, Dobbing J, eds. Scientific Foundations of Pediatrics, Philadelphia, PA, WB Saunders 1974; 469-498.
7. KauppilaA, Koivisto M, Pukka M, Tuimala R. Umbilical cord and neonatal cortisol levels. Obstetrics and Gynecology 1978; 52(6):666-672.
8. Gunnar Mr. Reactivity of the hypothalamic-pituitary-adrenocortical system to stressors in normal infants and children. Pediatrics 1992; 90(3):491-497.
9. Kirschbaum C, Hellhammer DH. Salivary cortisol in psychobiological research: an overview. Neuropsychobiology 1989; 22:150-169.
10. Kirschbaum, C, Hellhammer DH. Salivary cortisol in psychneuroendocrine research: recent developments and application. Psychoneuroendocrinology, 1994; 19(4): 313-333.
11. Jones DA, Rolhnan GB, Brooke RI. The cortisol response to psychological stress in temporomandibular dysfunction. Pain, 1997; 72:171-182.
12. Francis S J, Walker RF, Riad-Fahmy D, et al. Assessment of adrenocortical activity in term newborn infants using salivary cortisol determinations. J Rediatr 1987; 111:129-133.
13. Han J, Zhou Z, Xuan Y. Acupuncture has an analgesic effect in rabbits. Pain 1983; 15:83-91.
14. Pomeranz B, Cheng R. Suppression of noxious responses in single neurons of cat spinal cord by electroacupuncture and its reversal by the opiate antagonist nalozone. Experimental Neurology 1979; 64:327-341.
15. Part IV. Clinical research on acupuncture anesthesia. In: Xiangtong Z, ed. Research on Acupuncture, Moxibusion, and Acupuncture Anesthesia. Beijing an Berlin: Science Press with Springer-Verlag; 1986; 961-1179.
16. Cheng RSS. Neurophysiology of electroacupuncture analgesia. In: Pomeranz B, Stux G, eds. Scientific Bases of Acupuncture. Berlin: Springer-Verlag; 1989; 119-136.
17. Han J. Central neurotransmitters and acupuncture analgesia. In: Pomeranz B, Stux G, eds. Scientific Bases of Acupuncture. Berlin: Springer-Voting 1989; 7-33.
18, Pomeranz B, Paley D. Electroacupuncture hypalgesia is mediated by afferent nerve impulses: an electrophysiological study in mice. Experimental Neurology 1979; 66:398-402.
19, Cheng RSS, Pomeranz B, Monoaminergic mechanism of electroacupuncture analgesia. Brain Research 1981; 215:77-92,
20. Unschuld PU. Medicine in China: a history of ideas. Berkeley: University of California Press 1985.
2I. Scroll One. In: Wu J-N, translator. Ling Sbu: the spiritual pivot. Washington, DC: The Taoist Center 1993; 1-26.
22. Chapter Six. Source theory. In: Matsumoto K, Birch S. Hara diagnosis: reflections on the sea. Brookline, MA: Paradigm Publications 1988; 97-129.

AUTHOR INFORMATION
     Dr. Lynnae Schwartz is a Pediatrician/Anesthesiologist; her subspecialties include Pediatric Anesthesia and Critical Care. Affiliations include Department of Critical Care Medicine and Anesthesia, Children's National Medical Center, Washington, DC, and George Washington University School of Medicine, Washington, DC. Dr. Schwartz has a Master's degree from the New England School of Acupuncture, 1996.
     Lynnae Schwartz, M.D.
     Department of Critical Care Medicine and Anesthesia
     Children's National Medical Center
     111 Michigan Avenue, NW
     Washington, DC 20010-2970
     Phone: 202-884-3596 · Fax: 202-884-5724 · Email lschwart@cnmc.org

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