physiology of delivery. analgesia in labor
DESCRIPTION
Physiology of delivery. Analgesia in labor. Korda I. Labor. Labor is the physiologic process by which a fetus is expelled from the uterus to the outside world. It involves the sequential integrated changes in the uterine decidua, and myometrium. - PowerPoint PPT PresentationTRANSCRIPT
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LaborLabor is the physiologic process
by which a fetus is expelled from the uterus to the outside world.
It involves the sequential integrated changes in the uterine decidua, and myometrium.
Changes in the uterine cervix tend to precede uterine contractions
Dilatation: the enlarging of the cervix to 10 centimeters.
Effacement: the thinning of the cervix. cervix starts out being two inches long, and 50% effaced would be a 1 inch cervix.
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Cervical effacement and dilation
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Labor - Mechanics Uterine contractions have two major goals:1. To dilate cervix2. To push the fetus through the birth canal
Success will depend on the three P’s: Powers
Passenger Passage
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PowerUterine contractionsPower refers to the force
generated by the contraction of the uterine myometrium
Activity can be assessed by the simple observation by the mother, palpation of the fundus, or external tocodynamometry.
Contraction force can also be measured by direct measurement of intrauterine pressure using internal manometry.
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Power
Generally 3-5 contractions in a 10 minute period is considered adequate labor
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Passenger Passenger =fetus
Fetal variables that can affect labor:Fetal Lie – the relationship of the long axis of the fetus to the long
axis of the mother:longitudinal, transverse or oblique
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Fetal size
40 weeks 20.16 inches 7.63 pounds 51.2 cm3462 grams
41 weeks 20.35 inches 7.93 pounds 51.7 cm3597 grams
42 weeks 20.28 inches 8.12 pounds 51.5 cm3685 grams
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Fetal presentationthe part of the fetus that lies
closest to or has entered the true pelvis. Cephalic presentations are vertex, brow, face, and chin. Breech presentations include frank breech, complete breech, incomplete breech, and single or double footling breech. Shoulder presentations are rare and require cesarean section or turning before vaginal birth. Compound presentation involves the entry of more than one part in the true pelvis,
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Attitude – degree of flexion or extension of the fetal head
A--Complete flexion. B-- Moderate flexion. C--Poor flexion. D--Hyperextension
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Position - the relationship of the part of the fetus that presents in the pelvis to the four quadrants of the maternal pelvis, identified by initial L (left), R (right), A (anterior), and P (posterior). The presenting part is also identified by initial O (occiput), M (mentum), and S (sacrum)
Number of fetusesPresence of fetal anomalies –
hydrocephalus, sacrococcygeal teratoma
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The Fetal Skull
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Fetal Positions for Labor and Birth
Left Occiput Anterior (LOA)
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Left Occiput Transverse (LOT)
Left Occiput Transverse (LOT)
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Left Occiput Posterior (LOP)
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Right Occiput Anterior (ROA)
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Right Occiput Transverse (ROT)
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Right Occiput Posterior (ROP)
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Leopold's Maneuvers
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StationStation – degree of
descent of the presenting part of the fetus, measured in centimeters from the ischial spines in negative and positive numbers.
-5 is a floating baby,
0 station is said to be engaged in the pelvis,
and +5 is crowning.
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PassagePassage = PelvisConsists of the bony
pelvis and soft tissues of the birth canal (cervix, pelvic floor musculature)
Small pelvic outlet can result in cephalopelvic disproportion
Bony pelvis can be measured by pelvimetry but it not accurate and thus has been replaced by a clinical trial of labor
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Passage
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The Stages of Labor
First StageInterval between the
onset of labor and full cervical dilation
Two phases:Latent phase – onset of
labor with slow cervical dilation to ~4 cm and variable duration
Active phase – faster rate of cervical change, 1-1.2 cm /hour, regular uterine contractions
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The Labor Curve
First stage - A: latent phase; B + C + D: active phase; B: acceleration; C: maximum slope of dilation; D: deceleration; E: second stage.
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LaborFreidman’s
curve is a good guideline for expected progression in labor and therefore helpful to note abnormal labor patterns.
Labor NulliG MultiG
1st Stage Active phase
Duration 6-18 h 2-10 h
Dilation ~1 cm/h ~1.5 cm/h
2nd Stage 0.5-3 h 5-30 min
3rd Stage 0-30 min 0-30 min
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Fig 1: An idealized labor pattern. The normal patterns of cervical dilation (solid line) and descent (broken line) as they are traced against elapsed time in labor. The distinctive phases of the first stage are shown. The active phase comprises the interval from the onset of the acceleration phase to the beginning of the second stage.
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Labor – Second Stage Interval between full
cervical dilation to delivery of the infant.
Characterized by descent of the presenting part through the maternal pelvis and expulsion of the fetus.
Indications of second stage:
1. Increased maternal show
2. Pelvic/rectal pressure3. Mother has active role
of pushing to aid in fetal descent.
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Labor – Second StageMolding is the alteration of
the fetal cranial bones to each other as a result of compressive forces of the maternal bony pelvis.
Examining the fetal head during the second stage may become difficult due to molding
Caput is the localized edematous area on the fetal scalp caused by pressure on the scalp by the cervix.
PrimiG – 0.5-3 h; mulitG 0-30min
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Cardinal Movements of Labor
This refers to the movements made by the fetus during the first and second stage of labor. As the force of the uterine contractions stimulates effacement and dilatation of the cervix, the fetus moves toward the cervix.
When the presenting part reaches the pelvic bones, it must make adjustments to pass through the pelvis and down the birth canal
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Seven distinct movements:
1.Engagement2.Descent3.Flexion4.Internal
rotation5.Extension6.External
rotation/restitution
7.Expulsion
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Descent: As the fetal head engages and descends, it assumes an occiput transverse position because that is the widest pelvic diameter available for the widest part of the fetal head.
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Flexion: While descending through the pelvis, the fetal head flexes so that the fetal chin is touching the fetal chest. This functionally creates a smaller structure to pass through the maternal pelvis. When flexion occurs, the occipital (posterior) fontanel slides into the center of the birth canal and the anterior fontanel becomes more remote and difficult to feel. The fetal position remains occiput transverse.
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Internal Rotation: With further descent, the occiput rotates anteriorly and the fetal head assumes an oblique orientation. In some cases, the head may rotate completely to the occiput anterior position
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Extension: The curve of the hollow of the sacrum favors extension of the fetal head as further descent occurs. This means that the fetal chin is no longer touching the fetal chest.
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External Rotation: The shoulders rotate into an oblique or frankly anterior-posterior orientation with further descent. This encourages the fetal head to return to its transverse position. This is also known as restitution.
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ExpulsionDelivery of the fetusAfter delivery of the
fetal head, descent and intraabdominal pressure by mother brings shoulder to the level of the symphysis
Downward traction allows release of the shoulder and the fetus is delivered.
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Suctioning the nasopharynx
Clamp the umbilical cord
Cut between the clamps
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Labor – Third Stage Placental separation and delivery.
The time from fetal delivery to delivery of the placenta
Signs of placental separation:
a. The uterus becomes globular in shape and firmer.
b. The uterus rises in the abdomen.
c. The umbilical cord descends three (3) inches or more further out of the vagina.
d. Sudden gush of blood.
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Labor – Third StagePlacenta is delivered using
one hand on umbilical cord with gentle downward traction. Other hand on abdomen supporting the uterine fundus.
Risk factor for aggressive traction is uterine inversion.
Obstetrical emergency!!Normal duration between 0-
30 min for both PrimiG and MultiG
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Inspect the placenta for completeness
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Labor – Fourth StageRefers to the time from delivery of the
placenta to 1 hour immediately postpartumBlood pressure, uterine blood loss and pulse
rate must be monitor closely ~ 15 minutesHigh risk for postpartum hemorrhage from:Uterine atony, retained placental
fragments, unrepaired lacerations of vagina, cervix or perineum.
Occult bleeding may occur – vaginal hematoma
Be suspicious with increased heart rate, pelvic pain or decreased
BP!!!!!!
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Analgesia in labor Discomfort during Labor
and BirthPain and discomfort experienced during labor have
two neurologic origins: visceral and somatic Neurologic origins
Visceral pain: from cervical changes, distention of lower uterine segment, and uterine ischemia
Located over the lower portion of abdomen Referred pain: originates in uterus, radiates to abdominal wall,
lumbosacral area of back, iliac crests, gluteal area, and down the thighs
Somatic pain: pain described as intense, sharp, burning, and well localized Stretching and distention of perineal tissues and pelvic floor to
allow passage of fetus, from distention and traction on peritoneum and uterocervical supports during contractions, and from lacerations of soft tissue
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Expression of painPain results in
physiologic effects and sensory and emotional (affective) responses
Emotional expressions of suffering often seenIncreasing anxietyWrithing, crying, groaning,
gesturing (hand clenching and wringing), and excessive muscular excitability
Cultural expression of pain varies
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Factors influencing pain response
Physiologic factorsCultureAnxietyPrevious experience
Childbirth preparation
Comfort and support
Environment
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Distribution of labor pain A. Distribution of labor pain during first stage B. Distribution of labor pain during later
phase of first stage and early phase of second stage
C. Distribution of labor pain during later phase of second stage and during birth
(Gray shading indicates areas of mild discomfort; light-colored shading indicates areas of moderate discomfort; dark-coloredshading indicates areas of intense discomfort.)
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Nonpharmacologic Managementof Discomfort
Nonpharmacologic measures often simple, safe, and inexpensive
Provide sense of control over childbirth and measures best for woman
Methods require practice for best results
Try variety of methods and seek alternatives, including pharmacologic methods, if measure used is not effective
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Nonpharmacologic Managementof Discomfort
Childbirth education Dick-Read method(recommended the need for education and his
teaching method included lectures, exercise, and a focus on breathing and relaxation techniques.
Lamaze method Bradley method
Relaxing and breathing techniques Relaxation Imagery and visualization Music Touch and massage Breathing techniques Effleurage and counterpressure Water therapy (hydrotherapy)Transcutaneous electrical nerve stimulation
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Pharmacologic Managementof Discomfort
Nerve block analgesia
and anesthesiaLocal perineal infiltration
anesthesia
Prudendal nerve block
Spinal anesthesia (block) Disadvantages
Medication reactions (allergy)
Hypotension
Ineffective breathing
Headache Autologous epidural blood
patch
Sedatives
Analgesia and anesthesiaAnesthesia
Systemic analgesia Opioid agonist analgesics
Opioid (narcotic) agonist–antagonist analgesics
Co-drugs
Ataractics
Opioid (narcotic) antagonists
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Pain Pathways and Sites of Pain Pathways and Sites of Pharmacologic Nerve BlocksPharmacologic Nerve BlocksA. A. Pudendal block; suitable Pudendal block; suitable
during second and third stages during second and third stages of labor and for repair of of labor and for repair of episiotomyepisiotomy
B.B. Epidural block; suitable Epidural block; suitable during all stages of labor and for during all stages of labor and for repair of episiotomyrepair of episiotomy
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Membranes and spaces of spinal Membranes and spaces of spinal cord and levels of sacral, cord and levels of sacral, lumbar, and thoracic nerveslumbar, and thoracic nerves
Cross section of vertebra and Cross section of vertebra and spinal cordspinal cord
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Levels of Anesthesia Necessary for Cesarean
and Vaginal Births
Cesarean birth
Vaginal birth
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Administration of medicationIntravenous routeIntramuscular routeSpinal nerve block
Maternal fluid balance is essential during spinal and epidural nerve blocks
Maternal analgesia or anesthesia potentially affects neonatal neurobehavioral response
Use of opioid agonist-antagonist analgesics in women with preexisting opioid dependence may cause symptoms of abstinence syndrome (opioid withdrawal)
General anesthesia rarely used for vaginal birthMay be used for cesarean birth or when needed in
emergency childbirth situation
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Expected outcome of preparation for childbirth and parenting is “education for choice”
Nonpharmacologic pain and stress management strategies are valuable for managing labor discomfort alone or in combination with pharmacologic methods
Gate-control theory of pain and stress response are bases for many of the nonpharmacologic methods of pain relief
Type of analgesic or anesthetic used is determined in part by stage of labor
and method of birth
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Regarding Labour:the latent phase may last for more than four
hours the active phase should be associated with
cervical dilatation at a rate of at least 1 cm. per hour
the active phase starts when the cervix is effaced and 2 cm. dilated
involves artificial rupture of the membranes is best charted using a partogram epidural anaesthesia has an adverse effect on
the rate of progress in the 1st. stage of labour
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the latent phase may last for more than four hours
the active phase should be associated with cervical dilatation at a rate of at least 1 cm. per hour
the active phase starts when the cervix is effaced and 2 cm. dilated
involves artificial rupture of the membranes
is best charted using a partogram epidural anaesthesia has an
adverse effect on the rate of progress in the 1st. stage of labour
T
T
F
F
T
F
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During delivery, what comes next after Engagement, Descent, and Flexion?
1. Internal Rotation. 2. Extension. 3. External Rotation. 4. Expulsion.
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During delivery, what comes next after Engagement, Descent, and Flexion?
1. Internal Rotation. 2. Extension. 3. External Rotation. 4. Expulsion.
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In SummaryKnow the different stages of laborKnow the labor curveKnow the cardinal movements of labor
Know the causes of postpartum hemorrhage
MD must understand medications, expected effects, potential adverse reactions, and methods of administration
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Thank you for your attention!