Lecture 1 Flashcards
Gravida refers to what?
Number of pregnancies (not babies)
Para refers to what?
number of births (including still born deliveries at >20weeks)
What is G0P0?
Nulligravida/Nulliparous
- No pregnancies
- No births
What would G3P2 refer to?
Multigravida/ Multiparous
- 3 pregnancies (2 births/1 miscarriage)
- 2 births
How long is a pregnancy? When is a gestation “term”?
- 40 weeks
- Term at 37 - 40 weeks
What is the minimum expected weight gain during pregnancy? What are the components that account for this weight gain?
12 kg minimum weight gain:
- Uterus = 1 kg
- Amniotic Fluid = 1kg
- Fetal/Placental Weight = 4kg
- New Fat/Protein stores = 4kg
- Blood volume increase = 2kg
Describe the impact BMI has on total weight gain and rate of weight gain during pregnancy?
How much does total blood volume increase during pregnancy? What are some common symptoms exhibited secondary to this change?
30 - 35% increase
Increased blood volume is responsible for bloating and fluid retention (swelling)
When does the increase in total blood volume of the typical pregnant woman occur?
8 - 32 weeks (Majority by 24 weeks)
Blood volume increases with pregnancy are a result of increases in which specific blood volumes? What is a hematologic consequence of this change?
Plasma volume and RBC volume increase
plasma volume increases more than RBC volume.
Dilutional anemia (usually not significant)
Why does blood volume increase during pregnancy?
To counteract delivery blood loss
Approximately when does maternal blood volume return to normal post-delivery?
6 weeks postpartum.
Compare the blood volume of a pregnant patient and a non-pregnant patient in mL/kg.
Non = 65mL/kg
Pregnant= 85-90 mL/kg
CO will increase by ___% by term.
40%
In regards to hemodynamics, by 6 weeks there will be an increase in maternal _____ ____ and by 8 - 10 weeks there will be an increase in _____ _____.
Heart Rate : Stroke Volume
What is the mechanism for increased Stroke Volume in the pregnant patient?
↑ Plasma Renin = ↑aldosterone = ↑ Preload = ↑ SV
How much does uterine blood flow increase during pregancy?
Baseline = 50 mL/min
Term = 700 mL/min
10-20x increase in UBF
What is the cause of the pregnancy symptoms of warm skin, flushing, and itching?
3-4x increase in skin blood flow
What changes in SVR occur in pregnancy?
20% lower
What hormones are responsible for maternal vasodilation?
“PREP”
- Progesterone
- Relaxin
- Estrogen
- Prostacyclin
Pregnancy is a ____ flow, _____ resistance state.
High flow : low resistance; resulting from
maternal vasodilation
low resistance placental circulation
-uterine vascular bed has low resistance secondary to massive vasodilation (increasing placental flow)
decreased renal vasculature resistance
Do the following increase or decrease during pregnancy?
- Blood volume
- Cardiac Output
- SVR
- ↑ Blood volume (↑ preload)
- ↑ Cardiac Output (↑HR/↑SV)
- ↓ SVR (↓ after load)
What changes are seen in a maternal heart due to pregnancy? Why does this change occur?
Eccentric Hypertrophy (as much as 50%)
Occurs to accommodate for increased blood volume and preload.
How does the heart shift due to pregnancy?
Why does this occur?
- Heart shifts anterior and leftward due to diaphragmatic elevation.
Where does the point of maximal impulse for auscultation shift in a pregnant patient?
Shifts up and to the left. 4th ICS mid-clavicular line (normally 5th ICS mid-clavicular line)
What EKG changes are seen in a pregnant patient?
- Left Axis shift in 3rd trimester
- Lead III T-wave inversion
- PR interval shortened (d/t ↑ SNS activity in 3rd trimester/accelerated AV node conduction velocity)
- ST segment depressed
- QT interval increased (often still WNL)
What are the most common EKG abnormalities in pregnant patients?? How may these EKG changes present to the patient?
Tachydysrhythmias
-(Sinus tach, PAC, PVC)
Pt may experience palpitations, heart pounding etc.
What valvular changes are typical of pregnancy?
- Tricuspid & Pulmonic regurgitation (>90% pts)
- Mitral regurgitation (~25-30%)
These typically reverse postpartum.
What heart sound is often heard in the 3rd trimester?
What causes this?
S3/third heart soundVentricular Gallop
Due to large volume of blood rushing into highly compliant left ventricle.
What heart sound disappears at term? What is the cause of this sound?
4th heart sound (low pitched sound)
-caused by late diastolic filling of ventricle d/t atrial contraction
What murmur can occur due to cardiac enlargement?
Where is this best heard?
- Grade II SEM (systolic ejection murmur)
- Heard right side of heart, near sternal border
What are the hemodynamic consequences of lying in the supine position during pregnancy? What is the mechanism behind this change and when does this begin to occur?
Aortocaval compression
Gravid Uterus compresses inferior vena cava and aorta.
Occurs as early as 13-16 weeks.
What factor exacerbates aortocaval compression?
Anesthesia due to vasodilation
What are the s/s of aortocaval compression?
- Fetal Distress
- Tachycardia (initially) → bradycardia (if compression persists)
- N/V
- Pallor
- Loss of consciousness
What is the treatment for aortocaval compression?
LUD (Left Uterine Displacement)
-displaces uterus off of vena cava and aorta
Done by tilting the patient to the left
What cardiovascular changes occur during the first stage of labor?
- CO increases before & during contractions
- HR increases (to meet metabolic demands)
- Autotransfusion of 300-500mls from uterus to general circulation w/ each contraction.
What cardiovascular changes occur during the second stage of labor?
CO increases by 50% due to:
- Pushing effort
- ↑ SV (dramatic increase)
- ↑HR
How does CO change immediately after delivery? What is responsible for these changes? When does CO return to normal post-delivery?
CO: ↑60-80%
-Relief of pressure on vena cava
-uterine contractions continue/releasing blood into systemic circulation
-begins to decline 10 mins after delivery
-returns to normal 24 hours postpartum
What happens to the airway in obstetric patients?
What are the anesthetic implications of edematous airways?
- Smaller ETT necessary
- Avoid NGT/Nasal trumpets (bloody nose)
- Airway obstruction risk increases
- Mallampati class may progressively worsen (even during labor)
How does the hormone estrogen affect the obstetric patient’s pulmonary system?
Estrogen will ↑ number and sensitivity of progesterone receptors in the respiratory center of the brain.
How does the hormone Progesterone affect the obstetric patient’s pulmonary system?
- ↑ respiratory center sensitivity to CO₂
- Bronchodilates
- Causes hyperemia (excess blood) and edema of respiratory passages
How does the hormone Relaxin affect the obstetric patient’s pulmonary system?
Causes ligamentous attachments to lower ribs to relax. (ribs widen)
- subcostal angle increases
- widened AP & transverse diameter of chest wall (barrel chest)
How is Total Lung Capacity affected during pregnancy?
Preserved.
Chest height is shortened but A-P dimension increases with barrel shape due to relaxin.
chest wall widening helps compensate for decreased lung expansion secondary to decreased abdominal space
What is FRC?
Volume of air that prevents complete emptying of lungs and keeps small airways open.
amount of air in lungs after expiration
FRC= RV + ERV
3L = 1.5 L + 1.5L
What is ERV?
Volume of air that can be expired with maximum effort at the end of normal expiration.
What is RV?
Residual Volume = Volume of air in the lungs after ERV is expired
cannot be directly measured
RV = FRC - ERV
Uterine elevation of the diaphragm results in a _____% decrease in FRC.
20% ↓ in FRC (Both ERV and RV are decreased).
What causes the earlier closure of small airways in the obstetric patient?
Elevated Diaphragm → pleural pressure becomes more positive → earlier closure of small airways
(decreased FRC, ERV and RV)
What position results in a more profound decrease in FRC?
Supine position results in FRC decrease of 30%
-diaphragm further elevated
-increased alveolar atelectasis
Closing capacity may exceed FRC
What happens if closing capacity exceeds FRC?
Small airway closure & V/Q mismatch leading to
O₂ desaturation.
What respiratory volumes are increased during pregnancy?
- VT ( increased metabolic CO₂ production and increased respiratory drive r/t progesterone)
- IC (Inspiratory Capacity)
IC= IRV + Vt
What respiratory volumes are unchanged by pregnancy?
- TLC (all lung volumes): d/t rib expansion/wider chest wall
- VC (IRV + VT + ERV)
*sum of vol moving in and out of lungs
What is the goal for pre-oxygenation?
Goal: bring O2 sat as close to 100% as possible
-denitrogenate the residual lung capacity
-maximize O2 storage of lungs
- denitrogenate and oxygenate bloodstream
What FeO₂ (fraction of expired O₂) is desirable?
0.9 or greater
What positioning is helpful for preoxygenation?
20° Reverse Trendelenburg
How much does O₂ consumption increase by term? What are some causes of this increased consumption?
20%
-increased metabolism
-increased metabolic needs of fetus, uterus, placenta
-increased work of breathing
-increased cardiac workload.
How do minute ventilation and alveolar ventilation change in pregnancy?
Both Increase.
RR increases by 1-2 breaths per minute, mediated by hormonal changes.
How do ABG’s change during pregnancy?
What does this result in?
As a result of Increased Ventilation:
-PaCO₂ decreases by 8-10 mmHg
-PaO₂ increases by 5 mmHg
Respiratory Alkalosis is normal in healthy pregnancies.
Compare and contrast a typical ABG vs an obstetric ABG.
What pulmonary change occurs during the first stage of labor?
Minute ventilation increases by up to 140%.
What pulmonary change(s) occurs during the second stage of labor?
- V̇T goes up by 200%
- Maternal CO₂ decreases by 10 - 15 (hyperventilation)
- O₂ consumption increases
- aerobic requirements increase
- Maternal lactate increases
Supplemental O₂ might be necessary.
What hematologic changes occur during pregnancy?
- Plasma volume increases more than RBC mass resulting in dilutional anemia.
- Hgb drops by 2.4 g/dL (from pre-pregnancy-36 wks)
- HCT decreases by 6.5%
What Hgb range do we like for maternal patients?
11 - 13 g/dL
- Less than 11 is abnormal
- > 13 due to hemoconcentration.
High risk for pre-eclampsia
↑ Hgb can indicate pathology
What changes occur with platelets during pregnancy?
- Normal 165 - 415
- No change to moderate decrease seen with pregnancy.
Why do we care about platelets in obstetric patients?
Risk for epidural hematoma from neuraxial techniques.
Point of this chart:
-Identify lowest PLT for epidural at your facility.
-FInd a minimum PLT count that you are comfortable starting epidural
Pregnancy produces a hypercoagulable or hypocoagulable state?
Hypercoagulable.
What coagulation factors increase due to pregnancy?
All of them, except II, V, XI, and XIII.
What coagulation factor has the most significant increase during pregnancy?
Factor 1 (Fibrinogen)
What is hyperfibrinogenemia? What are the pros and cons of this?
Fibrinogen (Factor I) > 400mg/dL at term
- Increased clotting efficiency
- Impaired fibrinolysis
Protects against hemorrhage, but risk of blood clot increases
What factors are increased at term gestation?
Will be on test
- I (Fibrinogen)
- VII (proconvertin)
- VIII (Antihemophilic factor)
- IX (Christmas factor)
- X (Stuart-Prower factor)
- XII (Hageman factor)
What factors are unchanged at term gestation?
Will be on test
- II (Prothrombin)
- V (Proaccelerin)
What factors are decreased at term gestation?
Will be on test
- XI (Thromboplastin antecedent)
- XIII (Fibrin-stabilizing factor)
- PT & PTT ↓ by 20%
- Fibrinolytic activity decreases in 3rd trimester
What occurs with WBC’s during pregnancy?
- Increase steadily to 9,000 - 11,000/mm3 throughout pregnancy
- Spike up to 34,000/mm3 during labor
How does immune function change during pregnancy?
- Polymorphonuclear Leukocyte function is impaired
-increases risk & severity of infection- autoimmune dz symptom improvement may be seen
- Antibody titers to certain diseases can decrease
-Measles, influenza A, and Herpes simplex
All parturient patients are considered to be full stomach. Why is this so?
Enlarged gravid uterus displaces stomach cephalad
Increased gastric pressure
Decreased competence of the LES
How does lower esophageal sphincter tone change throughout pregnancy?
- Tone decreases throughout pregnancy with the lowest tone occurring at term.
- LES tone normalizes at 4 weeks post-partum.
-remain aspiration risk for up to 4 weeks postpartum
What is Mendelson’s Syndrome?
Aspiration pneumonitis & inflammatory response of lung parenchyma
What puts one at greater risk of Mendelson’s syndrome? What is the primary preventative intervention for pregnant patients?
- pH < 2.5
- > 25mL gastric volume
Bicitra given to pregnant patients before delivery to neutralize gastric pH.
Uterus takes ____ weeks to return to normal size. The LES tone returns to normal around ________? What are the anesthesia implications in the postpartum period?
Uterus takes 6 weeks to return to normal size
LES tone returns to normal around 4 weeks.
Treat as full stomach for 4-6 weeks postpartum
What changes occur in the liver during pregnancy?
↑ risk of esophageal varices due to increased portal vein pressure.
Careful use of OGT
↑ Liver enzymes and cholesterol (this is normal)
-serum aspartate aminotransferase
-lactic dehydrogenase
-alkaline phosphatase
How is colloid oncotic pressure affected by pregnancy?
Colloid oncotic pressure decreases due to:
-decreased total protein
-decreased albumin to globulin ratio
decreases further after delivery/returns to normal 6 weeks postpartum
What occurs with pseudocholinesterase levels during pregnancy?
-pseudocholinesterase decreases by 25% before delivery
-decreases by 33% on 3rd postpartum day.
-return to normal 2-6 weeks postpartum
*Usually still okay to give Sux**.
When can cholestasis occur to parturient patients? What factors attribute to cholestasis?
Occurs during 3rd trimester (1/100 people)
Cause: biliary stasis and increased bile secretion
What are the s/s of cholestasis?
- Pruritis
- ↑ serum bilirubin
- abnormal LFTs
What are the consequences of cholestasis in obstetric patients?
- ↑ risk of cholelithiasis
- ↑ risk of cholecystectomy
- ↑ risk of cholestasis in subsequent pregnancies
During pregnancy the kidneys see a _____ increase in renal blood flow.
75%
-renal vasodilation
What are the results of increased renal blood flow during pregnancy?
- ↑ GFR
- ↑ Creatinine clearance
- ↓ Creatinine
- ↓ BUN
What BUN/Creatinine levels are typical of pregnant patients?
- BUN: 8 - 9 mg/dL at term
- Creatinine: 0.5 - 0.6 mg/dL at term
What changes in the urine can occur during pregnancy?
- Glucosuria common (tubular Glucose reabsorption can’t keep up with ↑ GFR)
- Proteinuria (can indicate pre-eclampsia)
-prenatal visits check urine for this reason
What would a finding of proteinuria possibly indicate in a parturient patient?
preeclampsia
What labs in a parturient patient suggest abnormal renal function?
- BUN > 15mg/dL
- Creatinine > 1.0 mg/dL
- Creatinine Clearance < 100 mL/min
Further evaluation required.
What occurs with the thyroid during pregnancy?
Enlargement by 50 - 70%
-increased risk of diff. airway
*Hypothyroidism in 10% pts**
What are the pancreatic function changes during pregnancy?
-Insulin resistance due to Human placental lactogen
Hormone that prepares the body for breastfeeding.
-Increased blood glucose
How does adrenal function change in the parturient patient?
↑ cortisol
-Increased by 100% in 1st trimester
-Increased up to 200% by term
↑ plasma endorphins
How does the anterior pituitary change during pregnancy?
Hyperplasia of lactotrophic cells
-↑ Prolactin secretion
-preparation for breastfeeding
-hyperprolactinemia (may l/t acne)
How does the posterior pituitary change during pregnancy?
Oxytocin secretion increases by 30% by term
- Stimulates contractions
- Breast milk letdown
- “Bonding hormone” Helps mother bond to baby postpartum
What nerves are commonly compressed and lead to nerve pain in pregnancy?
Sciatic
Meralgia paresthetica
-compression of lateral femoral cutaneous nerve at location that it exits pelvis
What is meralgia paresthetica?
- Compression of lateral femoral cutaneous nerve at exit site of pelvis
-Affects outer side of thigh
S/s:
-Tingling, numbness, and burning on lateral aspect of the thigh.
What is the reason for lots of pelvic pain during pregnancy?
Lumbar lordosis w/ anterior pelvic tilt and narrowing of intervertebral spaces.
Center of gravity changes
What CNS changes occur during pregnancy?
- ↑ CBF
- ↑ BBB permeability
- ↑ pain threshold
What is the mechanism for increased pain threshold for parturient patients?
- ↑ plasma endorphins
- Progesterone activates κ-opioid receptors
What occurs with the epidural space in pregnant women?
- ↑ Venous plexus volume (engorged veins)
- ↓ CSF volume
What is the result of increased venous plexus volume?
Engorged epidural veins
-decreased free volume of epidural space
-higher risk of venous puncture during epidural placement.
Decreased CSF
drug will reach higher concentration in lower CSF volume
What is the result of decreased CSF volume on local anesthetic spread?
↑ spread of LA
Parturient patients have an increased sensitivity to _______ neuromuscular blockers.
Non-depolarizing.
Roc & Vec
What can happen with succinylcholine administration in a pregnant patient?
Prolonged paralysis due to ↓ pseudocholinesterase activity
-not usually clinically significant with one dose of succinylcholine but can be
What is considered pre-term delivery?
Any delivery before 37 weeks.
What does the abbreviation G1P0 mean?
G1P0: two possible meanings
-pregnant currently/no children (1st pregnancy)
-pregnant once/miscarried before 20 weeks
For patient’s pregnant for the first time, what education may be necessary?
Patient may refuse epidural initially, but may decide to go forth with it once dilated further. Educate them on the benefits and address any concerns they have.
What considerations must be made for multiparous patients?
Multiple births may indicate:
-increased risk of bleed
-may have rapid delivery
What is the anticipated blood loss with vaginal delivery and c section?
Vaginal delivery: 500 mL
C section: 800 mL
What are the hormonal changes that lead to cardiac output increases in pregnancy?
Estrogen and progesterone l/t increased plasma renin activity and increased aldosterone concentration.
What are some benefits of maternal vasodilation? What is the earliest that these changes may be seen?
Benefits:
-maternal BP
-kidney function (via vasodilation of renal vasculature)
Seen as early as 5 weeks into pregnancy
From notes section, slide 13.
What leads mentioned in lecture will be positive with left axis deviation seen with pregnancy? Which are negative
Leads I and aVL are positive
Leads II and aVF are negative
How is blood flow and perfusion affected with aortocaval compression?
Decreased venous return to right atrium →
*Decreased cardiac output →
*Hypotension →
*Decreased uterine blood flow →
*Decreased perfusion to fetus
Why is it important to utilize LUD as a primary intervention when patient and fetus in distress?
-IF patient and baby not doing well it may be related to aortocaval compression.
-LUD is a quick fix and can help rule out other pathologies.
What are some interventions for a pregnant patient with difficulty breathing through nose?
Start simple, have pt blow nose
-may be r/t ↑ occurrence of rhinitis/congestion
Concern for high spinal may be relieved by basic interventions
Avoid nasal trumpet d/t ↑risk of nose bleed
How can pre-oxygenation be achieved?
- 3 - 5 VC breathes with tight face mask w/ 100% O₂
*mask straps may be used to help with tight seal - 8 deep breaths at O₂ flow rate 10L/min over 1 min.
When does dyspnea occur in pregnancy? What are some of the causes of dyspnea?
What are some causes of thrombocytopenia (Plt <150k) in pregnancy?
-Idiopathic
-hypertensive disorder of pregnancy
-gestational: no plt dysfunction or bleeding
-may be a side effect of pregnancy rather that malignancy
Low platelets may progress to preeclampsia and to HELLP syndrome
What is the occurrence of epidural hematoma and what are some of the potential side effects?
1:200,000- 1:250,000
Can cause temporary or permanent neurological damage
Is it appropriate to utilize epidural anesthesia for an emergency c section?
Depends on hospital/anesthesia group policy
-If patient is established and received adequate prenatal care, an epidural may be used.
-If patient is not established and no prenatal care, GETA for c section
How is gastric emptying affected with pregnancy?
Gastric emptying mostly unchanged
delayed during labor
For surgery in pregnant patient, if succinylcholine used and need for prolonged relaxation, what is crucial to assess?
Must check twitches before using non depolarizing drug. This will help identify pseudocholinsterase deficiency that would be seen with initial succinylcholine administration.
What are the implications of hypothyroidism during pregnancy? What is the treatment?
Increased incidence of fetal cognitive issues, spontaneous abortion, growth restriction, placental abruption if not treated.
TX: levothyroxine
How does the pituitary size change in pregnancy?
Size increase by 3x
What are some of the side effects of the hormone Relaxin?
Increased joint mobility
-sacroiliac pain
-knee pain
Overstretching of joints is possible
-caution with exercise/stretching
When do the following pregnancy related changes return to normal? Decreased pseudocholinesterase, LES tone, Colloid oncotic pressure, uterus tone, cardiac output..
24 Hours:
-Cardiac Output
4 weeks:
LES Tone
2-6 weeks:
-pseudocholinesterase
6 weeks:
-colloid oncotic pressure
-uterus size
