ANESTHESIA


• Laparoscopic & prolonged gynecologic surgeries usually performed under GA


Laparoscopic procedures require complete relaxation of abdominal wall (ie, paralysis)


Std anesthesia techniques & precautions apply


Many laparoscopic procedures require prolonged Trendelenburg positioning for access to pelvis; in some pts, this may cause hemodynamic compromise, difficulty ventilating


• Transvaginal procedures & many abdominal procedures may be performed under neuraxial anesthesia/sedation, particularly if pt not candidate for GA due to medical comorbidities (though precludes use of paralytics)


Examples: Dilation & curettage/evacuation, operative hysteroscopy, vaginal hysterectomy or abdominal hysterectomy in pts not candidates for GA


• Both minilaparotomies & some laparoscopic procedures (most commonly sterilization) may be performed under sedation w/ local anesthesia only


PARENTERAL ANALGESIA IN OBSTETRICS


• All nonneuraxial methods provide only partial relief of labor pain.


May help laboring women cope w/ pain


Useful in cases of absolute contraindication to or pt refusal of neuraxial anesthesia


• Opioids act as opioid receptor agonists: Mu, kappa, delta


G-protein–coupled receptors → ↓ intracellular Ca → inhibition of release of pain neurotransmitters. Distributed through brain, terminal axons of spinal cord afferents


• Xfer across the placenta is rapid & signif; fetal effects may limit use


Drug xfer affected by prot binding capacity, size, ionization


In general, all local anesthetics & opioids transfuse freely across the placenta


Fetal acidosis results in ion trapping → fetal drug accum


• Side effects of systemic opioids


Maternal: Sedation, respiratory depression, N/V


Fetal: Decreased fetal HR variability during labor; pseudosinusoidal HR pattern, respiratory depression at birth. Use short-acting opioid w/ no active metabolites, if poss. Monit fetus continuously during administration of systemic opioids. Avoid administration shortly before deliv.


Sedatives: Do not provide analgesia; typical use is for sleep/relaxation in latent labor




NEURAXIAL ANESTHESIA IN OBSTETRICS


• Most effective method for labor pain


• Also std for C/S, postpartum tubal ligations, urgent postpartum procedures whenever poss



• Indications for spinal/epidural anesthesia in labor


Maternal request


Anticipation of operative vaginal deliv or shoulder dystocia; breech extraction; high risk of C/S; Risk of hemorrhage; difficult intubation


Maternal condition where signif pain or stress would create medical risk (eg, sev respiratory or cardiac dz)


Maternal condition which could worsen & potentially limit use of neuraxial anesthesia later in labor course (eg, worsening thrombocytopenia or coagulopathy)


• Contraindications to spinal/epidural anesthesia in labor


Absolute: Maternal refusal, uncooperative pt; soft tissue infxn of site; uncorrected hypovolemia; uncorrected therapeutic anticoagulation; Lovenox w/i 24 h; certain spinal conditions (eg, ependymoma); sev thrombocytopenia (<50 K)


Relative: Certain spinal conditions (eg, discectomy, rod fusion); mod thrombocytopenia (<75 K); LP shunt, some neurologic dzs (ie, multiple sclerosis); fixed ­cardiac output conditions (ie, AS)


• Types of neuraxial blocks: Spinal, epidural, & CSE


Spinal:


Anesthetic/opioid delivered directly into spinal fluid w/ needle through dural puncture


Benefits: Rapid onset (2 min); 1/20 epidural dose used so less risk tox


Disadvantages: Limited duration (1–1.5 h)


Epidural:


Anesthetic/opioid delivered into epidural space via continuous infusion through catheter


Benefits: Ability to continuously infuse & adjust dosage as needed; pt controlled


Disadvantages: Slower onset (20 min), larger doses used (20× spinal doses)


CSE:


Meds delivered directly into spinal fluid, then catheter placed in epidural space


Benefit: Combination of rapid onset & ability to continuously infuse


Disadvantages: More technically challenging than epidural or spinal alone; increased risk of PDPH compared to spinal alone



Figure 4.1 Epidural block


< div class='tao-gold-member'>

Only gold members can continue reading. Log In or Register to continue

Stay updated, free articles. Join our Telegram channel

Jul 2, 2016 | Posted by in OBSTETRICS | Comments Off on ANESTHESIA

Full access? Get Clinical Tree

Get Clinical Tree app for offline access