Quiz 3 Flashcards
C/S: Common indications include
- failure to progress
- fetal distress
- fetal malpresentation
- previous C/S (or failed VBAC)
- maternal condition making vaginal delivery unsafe
- fetal condition making vaginal delivery unsafe
C/S: Indications For General anesthesia
- Acute severe fetal distress with no time for block
- Non-functioning epidural catheter
- Parturient has contraindication to regional block
- Regional block inadequate
- Patient refusal of block
anesthesia effects on the uterus
- Avoid hypotension, hypoxia, acidosis, hyperventilation.
- Limit time between uterine incision and delivery to less than 3 minutes.
- Infants exposed to GA have lower Apgar at one minute but no difference at 5 mins.
- No significant alteration in neurobehavioral scores with regional techniques.
largest and second largest predictor of difficult airway
Mallampti 4
Receding mandible
Antacid:
Sodium citrate used to raise gastric pH. May last only 15 min. Should be given to all pts prior to C/S (general or regional).
Ranitidine (Zantac):
H2 blocker, usually used in addition to antacid as it does nothing for acid that is already there. 50 mg iv dose. Max effect seen 2 hrs after administration
Metoclopramide (Reglan):
Decreases gastric volume within minutes after administration. May have antiemetic effects. Effects inhibited by opioids.
Patients for elective procedures should be NPO for __ hrs although still at risk for aspiration.
6
Critically important for denitrogenation:
At term O2 consumption increased 20-30%; this is accompanied by a decrease in FRC.
Propofol dose:
Dose 2.0-2.8 mg/kg
readily crosses the placenta
A single induction dose does not significantly change Apgar scores
Ketamine: dose and effects
Dose 1.0-1.5 mg/kg
Useful in the face of maternal hemorrhage as it supports the BP, also decreases risk of bronchospasm.
Side effects hypertension and dysphoria.
midazolam not used bc?
Causes more neonatal depression than other agents
Etomidate not used bc?
May cause transient adrenal suppression in the neonate
Muscle relaxants
- Rapid sequence induction is mandatory in all but the rarest of cases.
- No need for defasciculating dose prior to succinycholine (9% incidence of fasciculation at term)
- Any relaxant is safe as their hydrophilic charged nature significantly limits placental transfer.
- There have been cases of neonatal paralysis in infants with homozygous atypical pseudocholinesterase.
Maintenance of Anesthesia: Options
- Prior to delivery many practitioners will deliver 50% nitrous oxide and 2/3 MAC of volatile agent.
- Another option is to not use nitrous until the fetus is delivered and to use up to 1.2 MAC of volatile plus 2-3 mcg/kg of fentanyl. After delivery, reduce the volatile agent to 0.5 MAC or less and use nitrous oxide. Midazolam can also be given after delivery to reduce the likelihood of recall.
The uterine _______ to delivery interval does make a difference, possibly due to ____________.
incision
uterine artery spasm.
Greatest 2 Causes of death in parturients undergoing regional anesthesia for C/S
1 - Local toxicity
Physiological Effects of Regional: Pulmonary
- No effect on inspiration.
- Expiratory pressures and flows are reduced in proportion to decreased abdominal muscle strength.
- A sensory block above T2 often gives patients a sense of dyspnea – reassurance is helpful.
Epidural management for C/S:
- Dose catheter slowly. 15 cc of 2% lido or 3% 2-chloroprocaine should be given over 5 min, continuously question the patient for signs of local toxicity.
- 100-150 mcg of fentanyl via the epidural should also be given prior to incision
- NaHCO3 will speed the onset of lidocaine or 2-chloroprocaine
- The ideal block height is somewhere between T4-T8.
C/S Management with Epidurals: Breakthrough pain
- A bolus of 5cc of local
- Epidural or iv fentanyl
- Nitrous oxide
- Ketamine iv (keep total dose below 1 mg/kg) ~10 mg at a time
- Ask the surgeon to infiltrate with some local
- If epidural is clearly inadequate, convert to GA
Laboring women have ____ hypotension with spinals than non-laboring
less
_____________ for hypotension is now considered the drug of choice by many practitioners
phenylephrine
Far and away the best drug for spinal? Because?
Bupivicaine
combines quick onset with intermediate duration.
Bupivicaine dosing for spinal
Typically, 12-14 mg of hyperbaric bupivacaine combined with 10-25 mcg of fentanyl and 0.1-0.3 mg of Duramorph (preservative-free morphine) for spinal anesthesia
Side effects of adding duramorph?
increases risk of delayed respiratory depression
produces side effects such as:
- nausea
- pruritis
Once baby is delivered, administer _______, dose of _____ in a 1 liter IV bag
pitocin
20 units
Maternal Altered response to anesthesia
- Decrease in MAC
- Increased sensitivity to neuraxial agents
- Decreased plasma cholinesterase
- Decreased protein binding (more free drug)
- Limited drug information in parturients
Anesthetic agents deemed safe include:
- thiopental
- morphine
- meperidine
- fentanyl
- succinylcholine
- NDMRs
Anesthetic management in the parturient should be directed to:
- Avoidance of hypoxemia
- Avoidance of hypotension
- Avoidance of acidosis
- Maintain PaCO2 in the normal range for the parturient
- Minimize effects of aortocaval compression
In addition to standard monitors if possible, fetal heart rate and uterine activity should be monitored in women of ___ weeks GA or greater
20
When organized uterine activity is detected a Beta agonist like _______ can be used as a tocolytic. ________ may also work
ritodrine
Magnesium
Drugs to avoid:
- Benzodiazepines have been linked to congenital anomalies. Weeks 3-8 are most critical as that is when organogenesis occurs.
- It may also be wise to avoid nitrous oxide as it may interfere with B12 metabolism.
Elective procedures should be postponed until __ weeks after delivery.
6
Volatile agent may _______ preterm labor
suppress
Hematological diseases of the parturient
- Sickle Cell
- VonWillebrand’s
- Idiopathic thrombocytopenia
- factor V Leiden
- proteins C & S deficiency
- phospholipid Ab
Autoimmune Diseases of the parturient
- Systemic Lupus Erythematosus
- Systemic Sclerosis (Scleroderma)
- Myasthenia Gravis
- Rheumatoid Arthritis
Hyperthyroidism
- Patient may be receiving propranolol therapy.
- Fetal goiter may occur.
- Myocardium is sensitive to catecholamines.
- Potential for thyroid storm.
- High fever
- tachycardia
- agitation
- severe dehydration.
_________ may exacerbate hypotension following SAB
Propranolol
Anticipate ________ responses to pressors d/t hypersensitive myocardium. in what disease?
exaggerated
Hyperthyroidism
Neuroendocrine tumorof themedullaof theadrenal glands, or extra-adrenal chromaffin tissue that failed to involute,that secretes excessive catecholamines – norepinephrine and epinephrine
Pheochromoctyoma
_____________ can mimic preeclampsia
Pheochromocytoma
Pheochromocytoma: Elective C-section
- Pre-op therapy with α-blockers followed by β-blockers.
- Avoid β-blockade without prior α-blockade because of risks with unopposed α stimulation, severe HTN, etc.
Bronchial Asthma: C/S. Regional? GA?
Regional – epidural preferable to spinal block.
- Gradual onset – tolerate intercostal muscle weakness.
- Reports of bronchoconstriction following SAB.
GA – avoid if possible – ETT can trigger bronchospasm.
- Avoid H2 blockers (cimetidine, ranitidine) – can increase sensitivity to histamine that causes spasm.
- Consider atropine or glycopyrrolate to decrease secretions.
- Ketamine for induction – bronchial relaxation.
- Avoid Desflurane.
Paraplegia
- Triggered by stimulation of skin, distension of hollow viscus (bladder, uterus).
- Pilomotor erection, sweating, flushing, headache, severe HTN, bradycardia.
- Avoid Succinylcholine d/t risk of hyperkalemia
Multiple Sclerosis: Concerns w/ neuraxial anesthesia
- Potential neurotoxic exposure of demyelinated spinal cord.
- Concerns over relapse of symptoms.
- Do not exceed concentrations > 0.25% bupivacaine infusions. Use lowest concentration and volume of local anesthetic that can achieve analgesia.
Brain Tumor
Major concern – brain herniation and death following rapid CSF reduction with dural puncture. Review radiographic studies for evidence of mass effect.
Benign Intracranial Hypertension
Pseudotumor cerebri
- NOT mass-related
- Epidural or spinal block is OK.
Look at slide 18 OB6
.
Myesthenia gravis contraindicated drugs
ABX
- Gentamycin
- Kanamycin
- Streptomycin
- Plymyxin
- Colistin
- Tetracycline
- Lincomycin
Tocolytics
-Magnesium Sulfate
Cardiac Meds
- Quinidine
- Propranolol
Beta Adrenergics
- Ritodrine
- Terbutaline
Others
- Quinine
- Penicillamine
- Lithium
Neostigmine for myesthenia gravis
- Maintain on normal regimen
- IV dose is given in ratio of 30:1 to oral dose
- Monitor fetal HR closely
- Observe for s/s of “cholinergic crisis”
Look at slide 21 OB6
.
Myasthenia Gravis: Cholinergic crisis symptoms, and Tx
- Profound muscle weakness
- Respiratory failure
- Loss of bowel and bladder function
- Disorientation
- Diplopia
(Treat with IV and IM atropine)
Sickle cells that have more severe anemia, higher incidence of preeclampsia
HgbSS or HgbSC
how to avoid sickle cell crisis:
avoid:
- hypoxia
- hypotension
- dehydration
- hypothermia
- acidosis
- tourniquets!
Most common type of vWF, tx?
Most common – type 1, Rx with DDAVP 0.3 mg/kg
No DDAVP in type 3, can increase bleeding
look at slide 31 OB6
.
look at slide 35 OB6
.
Amphetamines: CNS stimulants
- catecholamine depletion -> limited response to indirectly acting sympathomimetics, e.g. ephedrine
- Increased MAC for GA
- Increased volatile agent = inc. risk uterine atony
look at slide 38 OB6
.
HIV Infection
Pharyngeal lymphatic hypertrophy can create potentially difficult airway.
Cardiac Disease
- cardiac output is highest (~80% above baseline, immediately following delivery), this will be stressful for a pt with cardiomyopathy…
- Hypotension d/t dec. afterload will reverse a L>R shunt, with resultant R>L shunting and cyanosis – Beware SAB in these patients…
