Physiology of labor. Anesthesia in labor

LABOR–is the physiology process whereby regular uterine activity causes progressive cervical dilatation and usually results in delivery of the fetus, after 22 weeks of pregnancy.

- Labor is a physiologic process that permits a series of extensive physiologic changes in the mother to allow for the delivery of her fetus through the birth canal.- It is defined as progressive cervical effacement, dilatation, or both, resulting from regular uterine contractions that occur at least every 5 minutes and last 30-60 seconds.

Classification of labor

PRETERM LABOR– delivery the fetus from the cavity of uterus in 22-36 weeks of pregnancy.

TERM LABOR- delivery the fetus from the cavity of uterus in 37-42 weeks of pregnancy.

Delayed labor- delivery the fetus from the cavity of uterus after 42 weeks of pregnancy.

Theories, which explain the mechanism of birth beginning

Mechanical Immune Placenta Chemical Endocrine Modern

Forerunners of labor

The bottom of uterus is lowering Insertion of pre-lying part Krestellers cork is going away. Reductions of woman’s weight. Irregular muscular contractions of

uterus. Maturity of uterus’s cervix

BISHOP’S SCALESigns Score

0 1 2

Consistency of uterus’ cervix

Thick Softened, but thick in the area of internal os

Soft

Length and effacement of cervix

More than 2 сm 1-2 сv Less than 1 cm or effaced

Permeability of cervical canal or cervical os

External os is closed or lets pass trough fingertip only

Cervical canal lets pass one finger freely. Internal os is still present

Cervical canal lets pass more than one finger freely. If the cervix is effaced – dilatation more than 2 cm

Disposition of the cervix

Posterior Anterior Medial

0-2 points – uterus’ cervix is “immature”3-4 points – cervix is “mature but not enough”5-8 points – cervix is “mature”

Cervical effacement in nullipara women

Cervical dilataton in multipara women

Physiological Preliminary period

Characteristics:

1. Irregular uterine contractions.

2. There are no structure changes in the cervix of uterus.

3. Duration 6-8 hours

Labor begins with

Regular muscular contractions. Cervical effacement. Forming of amniotic vial.

Forewaters

Labor stages

І stage (cervical) – dilatation of the cervix (12-15 hrs.)

ІІ stage (pelvic) – starts from complete dilatation of cervix to the delivery of baby (1-2 hrs.).

ІІІ stage (placental)- starts from the birth of baby till delivery of the placenta. (5-30 min.).

The first period of labor

Uterine contractions – regular contractions of uteri musculature. Typically, contractions occur every 5-10 minutes and last for 20-25 seconds in the onset of labor.

As labor progresses, the contractions become more frequent, more intense, and last longer.

Characteristics of uterine contractions

Tonus – minimal pressure between contractions – 10-12 mm Hg.

Intensivity – difference between amplitude and basal tonus of uterus 30-50-70 mm Hg.

Frequency per 10 min – 3-4 за 10 хв. Duration – 35 - 93 сек. Rhythm - intervals between contractions – equal. Activity = intensivity х frequency per 10 min = 280-

340 Montevideo units

The second stage of labor

Bearing-down efforts (or pushing)

Is the periodic contractions of diaphragm, pelvic floor muscles and front abdominal which are add to the force of uterine contractions.

The birth canal

Record methods of labor

Tocography (external and inernal) Radiotelemetry. Electrogisterography. Cardiotocography.

Friedman’s curve

А – dynamic of cervical effacementБ – advancement of the presenting part of fetus

The partogram

Cardiotocography

Cardiotocography

Fetal blood sampling

Types of placenta separation

Shreder’s sign

Kustner’s sign

а) б)

Methods of obtainment of the separated placenta (afterbirth)

Abuladze. Genter. Krede-Lazarevich.

Method of Abuladze

Genter’s Method

Krede-Lazarevich’s method

Examination of placenta and membranes

Manual separation of placenta

Anesthesia in Labor

Causes of labor pain:-Hypoxia of uterine muscle-Stretching of the uterus’ lower

segment-Stretching of the uterus’ ligaments-Psychological causes

Modern methods of the pain relief:

- Non-medicamental

- Medicamental

Psychological training of pregnant women

- Decreases phychological component of pain

- Decreases fear of labor- Forms correct imagination about labor in patient

Lessons

1 lesson– anatomy and physiology, changes during pregnancy

2 lesson– 1st period of labor, correct behaviour of patient, role of partner;

3 lesson– 2nd and 3rd periods of labor; 4 lesson – port-partum period, breast feeding,

caring of baby; 5th lesson - revision.

Medicamental pain relief must have

Good effect Simplicity of usage Safety for mother and fetus!

Indications to Anesthesia:

No effect from the psychoprophylaxis;

Gestoses of the second half of pregnancy

Hard extragenital patology

Operative interferences ;

Labor abnormalities

Conditions

Regular uterine contractions Cervical dilation 4 cm+ Absence of contraindications

Drugs:

Promedol 1% - 1 ml Sibasone 0,5% - 2 ml

Epidural anaesthesia

Epidural anaesthesia

Epidural anaesthesia

Epidural anesthesia Anatomical abnormalities, such as spina bifida or scoliosis Previous spinal surgery (where scar tissue may hamper the

spread of medication, or may cause an acquired tethered spinal cord)

Certain problems of the central nervous system, including multiple sclerosis or syringomyelia

Certain heart-valve problems (such as aortic stenosis, where the vasodilation induced by the anaesthetic may impair blood supply to the thickened heart muscle.)

Bleeding disorder (coagulopathy) or anticoagulant medication (e.g. warfarin) - risk of spinal cord-compressing hematoma Infection near the point of intended insertion Infection in the bloodstream which may "seed" via the catheter into the (otherwise relatively impervious) central nervous system

Uncorrected hypovolemia (low circulating blood volume)

Local anaesthesia

Infiltrative anaesthesia (episiotomy, reparation of perineum

Lidocain2% 4-10 ml is used

Thank you!