Quiz 1 Flashcards
Neurological changes in pregnancy (4)
- MAC is decreased.
- Epidural space becomes smaller.
- Cerebrospinal fluid volumes are decreased and epidural veins are engorged.
- Increased sensitivity to local anesthetics.
REspiratory changes in pregnancy (net, rate, TV, MV, FRC, PaCO2)
Net effect is increased ventilation.
- Tidal volume increased ~40% at term.
- Respiratory rate increased ~15%.
- Minute ventilation increased ~50%.
- FRC decreases by ~20%
PaCO2 decreased to 28-32 mm Hg secondary to hyperventilation, i.e. respiratory alkalosis.
-Compensatory metabolic acidosis
P50 of hemoglobin increases from ___ to ___ mmHg.
Aids delivery of oxygen to fetus
27
30
maintain _____carbia during anesthesia. Why?
normo
decreased PaCO2 causes uterine constriction and decreased placental blood flow
cardiovascular changes in pregnancy. Why increase in volume?
- Increased plasma volume (~45%) in excess of red cell mass (RBC vol inc ~20%)
- increased cardiac output (inc 40%; 15-30% inc. HR and 30% inc. stroke volume)
- Peripheral vascular resistance drops about 15%
Inc. renin > inc. aldosterone > sodium/H20 retention
CO changes in 4 different phases of labor:
Latent Phase – inc. 15%
Active Phase – inc. 30%
Second Stage – inc. 45%
Postpartum – inc. 80%
Response to ________ drugs is blunted.
adrenergic
Supine Hypotension Syndrome
hypotension, pallor, nausea and vomiting and diaphoresis when they lie flat
These effects may be seen as early as 20 weeks gestation
Place patient in left lateral uterine tilt position
Coag changes in pregnancy: Increased? decreased? labs?
I, VII, VIII, IX, X, XII
XI, XIII
PT, PTT dec. 20%
Renal blood flow and glomerular filtration increased by about ____ by 16th week, remains elevated until delivery
50%
Hepatic changes in pregnancy
20% decrease in pseudocholinesterase levels.
Simultaneous increase in volume of distribution counters any clinically significant prolongation of NMB with succinylcholine
Fetal stores are about ___ ml of O2 and consumption is ___ ml/min
42
21
Compensatory mechanisms (redistribution, anaerobic metabolism) the fetus at term can survive ___ min of total O2 deprivation
10
Placental blood has a PaO2 of 40mm Hg, how is this compensated for?
the fetal oxy-hemoglobin dissociation curve is left shifted and the maternal curve is right shifted
how is transfer of CO2 accomplished?
simple diffusion across the placenta
Uterine blood flow represents ___% of cardiac output. 80% of this blood goes to the placenta, the rest goes to the ___________.
10 (600-700 ml per min in the parturient).
myometrium
Three Factors influence UBF:
- Systemic blood pressure
- Uterine vasoconstriction
- Uterine contractions
drugs that mildly reduce UBF via maternal hypotension (2)
Propofol and thiopental
Ketamine has no net effect at doses ____ mg/kg
<1.5
Volatile agents dec. UBF secondary to hypotension but at < __ MAC the effect is minor
1
High serum ________________ levels can result in uterine vasoconstriction
local anesthetic
look at slide 29 and 33, 34 OB1
.
Most common cause of postpartum maternal palsy is
cephalopelvic disproportion
Backaches from? (2)
- lumbar lordosis to counterbalance growing uterus.
- laxity of sacrococcygeal, sacroiliac, pubic joints.
insertion and removal of epidural should only occur when
coagulation function is normal
For patients with PIH a platelet count of over ______ and normal PT, PTT is required for Neuraxial block
100K
Look at slide 8 OB5
.
S/S epidural hematoma
- Bilateral leg weakness
- Incontinence
- Absent rectal sphincter tone
- Back pain
- If hematoma suspected pt must get a stat CT or MRI
- Surgical decompression must occur w/in 6 hrs for full neurological recovery to occur
S/S epidural abscess
- Severe back pain
- Worse with flexion; sometimes with radiation
- Exquisite local tenderness
- Fever, malaise, meningitis-like headache with neck stiffness
- Laboratory changes - Inc. WBC, inc. ESR, positive blood culture
- Progression over hours-days to neuro deficit or osteomyelitis
compression injuries in lithotomy stirrups (3)
- Common peroneal
- Obturator
- Femoral
Postpartum foot drop from?
common peroneal nerve from stirrups or brow compression of lumbosacral trunk
dec. sensation over upper inner thigh, weak hip adduction
obturator injury
difficulty climbing stairs
femoral injury
PDPH Risk Factors (5)
- Younger age
- Larger needle gauge
- Cutting-edge Quincke spinal needle
- Cephalad or caudal orientation of Quincke needle
- History of PDPH or migraines.
Gauge and chance of PDPH (5)
16-18 ga epidural – 75-80% chance of PDPH 22 ga Quincke – 30-50% chance of PDPH 25 ga Quincke – 8-10% chance of PDPH 24 ga Sprotte – 3-5% chance of PDPH 25 ga Whitacre – 1-2% chance of PDPH
The hallmark of a PDPH is
continuous head pain when patient sitting or standing that is completely or almost completely relieved by recumbence
Most common cause of perioperative headache
caffeine withdrawal
look at slide 26 OB5
.
look at slide 29-31 OB5
.
Management of Total Spinal
- Place patient in LUD and Trendelenberg
- Early resuscitation, ventilation, and circulatory support.
- Epinephrine may be needed
Look at slide 40 OB5
.
Tx of aspiration
Intubation and positive pressure ventilation w/ PEEP. Use only enough O2 to maintain O2 saturation in the 90s (high FiO2 may exacerbate lung injury)
