Presentation on theme: "1 Understanding Fetal Pain A Congressional Staff Briefing June 22, 2004 Jean Wright MD MBA Professor & Chairman of Pediatrics Mercer School of Medicine."— Presentation transcript:
1 Understanding Fetal Pain A Congressional Staff Briefing June 22, 2004 Jean Wright MD MBA Professor & Chairman of Pediatrics Mercer School of Medicine
2 Understanding Fetal Pain History of the scientific knowledge The historical context for regarding fetal pain. The premature infants demonstrates fetal development Why isn’t maternal anesthesia enough?
4 Fetal Pain - Not a new science More than 20 years of data In the early 70's, many pre-term infants were considered too ill to tolerate the effects of anesthesia in order to undergo their needed surgery. Even by the early 80's, pre-term infants still received minimal anesthesia in the operating room and NICU. The medical community did not think the fetus and the premature infant could feel pain. Anand in 1987 reported on premature infants that were operated upon without anesthesia. He measured ‘fight and flight’ hormones during and after surgery and clearly demonstrated that these infants not only felt pain, but had an intense response. He further showed that the untreated pain led to a poorer outcome in these infants.
5 1987 Turning Point It wasn't until two landmark articles published in 1987 (Anand and Green, Lancet,1987, and Anand and Hickey NEJM, 1987, with an accompanying editorial by Fletcher) that the practice of pediatric anesthesia began to change broadly. Fletcher, in that Editorial, comments that "unless a neonatologist had made a concerted effort to study the topic of pain, a subject that has not until now been in the forefront of concern in neonatal care, he or she would not have had easy access to more of the information in the Anand study" She highlights that among the 201 references, only 20 occurred in medical journals that might have been part of a neonatologist's regular reading.
6 International News News spread from the scientific community to the lay press and even to discussions in Parliament. Anand moved to Harvard and he and Hinchey continued the work. This information quickly entered the U.S. Scientific literature in New England Journal of Medicine and other scholarly publications.
7 Practice of Pediatric Anesthesia The practice of pediatric anesthesia changed. Care and attention to premature infants included the administration of IV anesthetics, particularly narcotics (Pain relieving substances). It soon became unacceptable to operate on premature infants without meeting their pain and stress needs.
8 Understanding Fetal Pain History of the scientific knowledge The historical context for regarding fetal pain The premature infants demonstrates fetal development Why isn’t maternal anesthesia enough?
10 Review of fetal development Conception 28 Weeks Birth First TrimesterSecond TrimesterThird Trimester
11 Review of fetal development Conception 28 Weeks Birth First TrimesterSecond TrimesterThird Trimester Fetal Viability 28 weeks in 1973
12 Legal Protection of Abortion Conception 28 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Roe V. Wade
13 Legal Protection of Abortion Extended Conception 28 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade
14 If 2004 definition of viability was used Conception 23 -4 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade
15 Late Term Abortions Conception 23 -4 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade Late Term Abortions
16 Current viability challenges even 2 nd Trimester abortions Conception 23 -4 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade Late Term Abortions 2 nd Term Abortions
17 Understanding Fetal Pain History of the scientific knowledge The historical context for regarding fetal pain The premature infants demonstrates fetal development Why isn’t maternal anesthesia enough?
18 The premature infant demonstrates fetal development
19 The neonatal intensive care view Premature infants led the way into understanding how the unborn fetus feels pain. Infants born prematurely have the same anatomy and physiology as their unborn counterparts. By studying the premature infant outside the womb allowed us to understand what was happening inside the womb. Same gestational age – one inside & one outside the womb
20 The premature infant as teacher of fetal medicine The premature infants demonstrates fetal development. The capacity of the fetus to experience pain Anatomy & Physiology of pain Increased sensitivity to pain Fetal consciousness
21 What is Pain? “an unpleasant sensory and emotional experience associated with actual or potential tissue damage, or described in terms of such damage. The inability to communicate verbally does not negate the possibility that an individual is experiencing pain and is in need of appropriate pain-relieving treatment.*” *The International Association for the Study of Pain
22 Non-verbal markers of Pain The human fetus is incapable of verbal expression, therefore other markers of pain must be used. Anatomical Functional Physiologic Behavioral These markers correlate with the same markers in children and adults.
23 Anatomic Development Pain is transmitted from the skin or surface tissues down electrical pathways to the spinal cord. They connect in the spinal cord and go to the brain. The brain receives the signals and then sends electrical impulses to other organs for their response. (Motion, vital signs, hormones). 1 2 3
24 Starting at the skin Specialized nerve endings feel pain. These are seen at 7 weeks around the mouth and face, and cover the entire body by 20 weeks. They are more densely configured per square inch than on an adult. Pain Nerve Ending 7 week fetus
25 Carrying the signal Until the nerve fibers are mature and coated with myelin, the pain signals are carried by fibers that will later carry touch. Neurons in the spinal cord (Dorsal horn neurons) develop before 13 weeks, and grow more complex throughout fetal life. Nerve fibers penetrate skin 8 and 13 weeks
26 Modulating pain response Over time, we learn to modulate our pain response. The brain sends inhibitory signals to the body to lessen our reactions. In the fetus, the ability to modulate (or inhibit pain) does not develop until 36 - 40 weeks gestation. Therefore, pain in the fetus and premature infant is unmodulated or unfiltered until the baby is almost full term in gestation.
27 Brain development Nerve cells in the brain during the first trimester demonstrate organization, differentiation, elaborate branching, and the presence of neurotransmitters. The nerve cells develop elaborate axons and dendrites. At the end of the nerves proteins are released when pain is signaled. These are the same biochemical markers present in adults. These markers imply a functional role early in development. Axon w/ neurotransmitters
28 Neurotransmitters measured at 19 - 21 weeks Neurotransmitters bind with specific receptors in a lock and key fashion. Opioid receptor labeling in the brain stem demonstrate very high densities in supraspinal centers associated with sensory perception. The neuro-endocrine mechanisms to regulate the pain however, are present, but the fetus’ ability to limit or modulate pain is underdeveloped.
29 Cerebral Cortex The cerebral cortex begins to form at 8 - 10 week. A subplate is formed by 15 weeks, and penetrated by fibers from below by 16 weeks. This development completes the final anatomical links needed for pain transmission to reach the brain. From 12 - 28 weeks, the number of cortical neurons will increase 10 fold. Feet of 11 week old
30 How do we know it isn’t just a reflex? Confusion between Knee Jerk Reflex and other reflexes. Cutaneous Flexor Reflex – often used in pain literature…. The study of this reflex has been used to establish when connection between the skin and the spinal cord are first made in the fetus. They have been used to study the maturation of ascending motor pathways. This reflex has been shown in man to parallel pain perception exactly in terms of threshold, peak intensity, and sensitivity to analgesics. Has a lower threshold in pre-term neonates than in term neonates or adults Knee Jerk Reflex
31 Physiologic Responses Medical studies of living fetuses demonstrate the ability to generate ‘fight or flight’ hormones in response to painful stimuli as early as 16 weeks. Catecholamines, B-endorphins, Cortisol When the needle is placed in the umbilical vein, (which has no pain fibers); no consistent responses occurred. When a needle is placed through the liver to give the fetus a transfusion, these hormones are released. The abdominal wall has pain fibers. And the liver aspiration produced changes proportional to the stimulus.
32 Response to pain relief The hormonal responses were reduced when fentanyl a pain relieving opiate was administered directly to the fetus. 16 week fetus Umbilical vein placement Transabdominal and liver placement
33 Other confirming studies Blood flow is redistributed in response to painful stimuli. When invasive procedures are done on fetuses, studies have revealed that blood flow to the brain was decreased within 70 seconds after a painful stimulation in fetus @ 16 weeks gestation Fetal blood sampling Body Cavity aspirations Fetal amniotic shunts This implies that if the pain signal had not reached the Thalamus in the brain, this redistribution of blood flow would not occur.
34 Increase Sensitivity To Pain In addition the pain fibers on their face and skin is more per square inch in the 20 - 30th week of gestation. The skin is very thin, leaving the pain fibers closer to the surface. When hormonal levels are measured in fetuses, they are 3 - 5 x the level found in full term infants and children. This is because they lack the inhibitory fibers. Translucent skin photo or 30 - 32 week fetus
36 Fetal Consciousness Three decades of research demonstrate that preterm infants and fetuses are perceiving, learning, and working to regulate themselves, their environment and their experiences. Preterm infants favor experiences that are developmentally supportive and actively avoid experiences that are developmentally disruptive.
37 British Commission of Inquiry into Fetal Sentience Consciousness is associated with shifting brain patterns that even in adults is not well understood. We may never have unequivocal evidence for fetal consciousness, since we cannot achieve that for adults. “Fetuses may be conscious from six weeks of gestation.”
38 Increased brain maturity is measurable over time From 20 weeks, fetuses respond to light, sound, taste and touch, with increasingly complex movements. If cortical activity is used to measure consciousness, then the EEG (electroencephalogram) demonstrates that at 19 - 20 weeks of gestation. Somatosensory Evoked Potentials (SEPs) can be recorded from 24 weeks. Fetuses can acquire distinct verbal memories from prenatal experiences (studies in the 3rd trimester) which continues to support that consciousness develops before delivery. 24 weeks
40 Why isn’t maternal anesthesia enough? Many obstetrical procedures are done with regional anesthesia (Spinal, epidural and local anesthestics). These agents do not provide anesthesia for the fetus. Intravenous anesthetics have to get into the mother’s blood, avoid metabolism by the mother’s liver, cross into the placenta, and reach the fetal circulation in significant amounts to cross into the fetus’ brain. To reach the infant, a higher maternal dose would have to be given, than is clinically indicated for the mother.
41 Fetal Surgery Implications Advances into fetal surgery have called for new advances into fetal anesthesia and fetal monitoring.
42 Development of the Late Term Fetus Conception 28 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade
43 Time frame for perceiving pain impacts all 3 trimesters Conception 23 -4 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade Late Term Abortions 2 nd Term Abortions First Term Abortions
44 Timeframe for pain perception during surgical and abortive procedures. Conception 23 -4 Weeks Birth First TrimesterSecond TrimesterThird Trimester Protected by Doe V. Bolton Protected by Roe V. Wade Late Term Abortions 2 nd Term Abortions First Term Abortions
45 Summary Markers of fetal pain perception start at the 7 th week and mature over the next 12 weeks. By week 20, the anatomy of the nervous system and the physiology of responding to the pain impulse draws a clear cause and effect relationship. Fetal responses are more than reflexes and infer consciousness. Fetal pain is more intense than that of term infants, and cannot be modulated or inhibited as in term infants. Maternal anesthesia alone is not enough.
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