Obstetrics

Miller pg 2230.   Although placing an epidural catheter can be technically challenging in obese patients, the incidence of PDPH following dural puncture is decreased.  This is thought to be due to the abdominal paniculus acting as an abdominal binder, increasing intraabdominal pressure and subsequently decreasing CSF leakage.



Question contributed by MMaloney MD.

Babies are expected to have some degree of acidosis immediately after they are born because the uterine contractions interrupt their blood supply repeatedly.



pH  7.26 (7.05- 7.38)

pCO2 55.0 (37-80)

O2 17 (6 - 30)



http://www.ajog.org/article/S0002-9378(96)70214-4/abstract

http://www.k2ms.com/documents/UmbilicalCordBloodSamplingEDCIndepthWeb2013.pdf

This fetal heart monitor shows a classic "late deceleration," which means that after the uterus contracts the fetal heart rate drops.  This happens because a uterine contraction interrupts blood flow across the placenta.  During a normal delivery, the baby has enough reserve that it can tolerate this momentary lapse in blood flow, but when the baby is already hypoxic, hypercarbic, and acidotic, it response to the contraction by decreasing the heart rate.  The heart consumes the most oxygen in the fetus, so slowing the rate prolongs survival on a lower oxygen supply.



Sweha A and Hacker T, Interpretation of the Electric Fetal Heart Rate During Labor, Journal of the American Family Physician, 1999 May 1; 59(9): 2487-2500.



available at: http://www.aafp.org/afp/1999/0501/p2487.html

This patient presents with signs and symptoms of severe Preeclampsia, and she received the correct treatment with: 1. Magnesium Sulfate (MgSO4) for seizure prophylaxis and 2. Labetalol for blood pressure control.  In the setting of damaged kidneys, the renal clearance decreases dramatically, and patients can experience Magnesium toxicity. This patient's increased sedation and respiratory depression are early signs.  Late signs of magnesium include heart blocks even complete cardiac arrest.


Calcium Gluconate is initial treatment of magnesium toxicity as it stabilizes the myocardium.  Diuretics and sometimes dialysis are definitive therapy.



Question contributed by MMaloney MD.

Sympathetic fibers from T1-T4 innervate the heart, so a spinal or epidural from T4 upward block that innervation and could cause a very dangerous bradycardia.



Barah, Clinical Anesthesia, 6th Edition, Chapter 37: Spinal and Epidural Anesthesia, pg. 947.

This fetal heart monitor shows a contraction and a heart rate deceleration that do not start or stop at the same time.  This is a called a "variable deceleration," and it is thought to be caused by compression of the umbilical cord.  



Sweha A and Hacker T, Interpretation of the Electric Fetal Heart Rate During Labor, Journal of the American Family Physician, 1999 May 1; 59(9): 2487-2500.



available at: http://www.aafp.org/afp/1999/0501/p2487.html

This fetal heart monitor (FHM) shows a classic "early deceleration."  This means that as the uterus contracts (shown by the increased pressure of the bottom line), the fetal heart rate decreases along with it.  Likewise, as the contraction resolves the fetal heart rate returns to baseline. 



The thinking is that the compression on the baby's head causes a vagal response in the fetal heart.



Sweha A and Hacker T, Interpretation of the Electric Fetal Heart Rate During Labor, Journal of the American Family Physician, 1999 May 1; 59(9): 2487-2500.



available at: http://www.aafp.org/afp/1999/0501/p2487.html

The only factor that is consistently associated with a change in the distance from the skin to the epidural space is a patient's BMI.  While some studies indicate that race has a correlation also, the evidence for this is still controversial. 



Ravi K et al, Distance from Skin to Epidural Space: Correlation to Body Mass Index (BMI), Journal of Anesthesia and Clinical Pharmacology, 2011 Jan;27(1):39-42.



article available at: http://www.ncbi.nlm.nih.gov/pubmed/21804704

While childbirth is normally associated with blood loss (500ml in vaginal birth and approximately 1L in a c-section), the blood loss can be more significant especially with a placental abruption, uterine rupture, uterine atony, DIC, or high-grade laceration.   While blood loss remains the leading cause of maternal death worldwide, pregnancy-induced hypertension (PIH) is more deadly in the US more recently.







Berg CJ, et al. Obstetrics and Gynecology 2010; 116:1302-1309.

According to the ASA Task Force on Obstetric Anesthesia, CBC is only indicated when there is history of bleeding or clotting disorder or if there is clinical suspicion.  Type and Screen

A list of the physiologic changes of a normal pregnancy includes:

 

1.  Increased blood volume ( >8 L at term)

2.  Increased cardiac output (peaks immediately after delivery)

3.  Dilutional anemia (normal Hb = 12

4.  Increased respiratory rate (PaCO2 is approximately 30)

5.  Decreased Bicarbonate (compensates for respiratory alkalosis)

6.  Decreased FRC

7.  Hypercoaguable state with increased fibrinogen, Factors VII, VIII, IX, X, XII

8.  Increased GFR and creatinine clearance





As fibrinogen should be significantly increased in pregnancy, when it is low it is an ominous sign of possible DIC.



Miller's Anesthesia, Chapter 69: Anesthesia for Obstetrics, 2009.

 

When an epidural is newly inserted or there is some uncertainty whether it is intravascular