OBGYN - Maternal-Fetal Physiology

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(OjTKwZ Very informative post.Really looking forward to read more.)
 
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=Maternal-Fetal Physiology=
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OjTKwZ Very informative post.Really looking forward to read more.
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==Objectives==
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*List pertinent physiologic changes in various maternal systems
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*Recognize that signs and symptoms in a pregnant patient are often more difficult to interpret
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*Non-pregnant lab values and measurements are frequently abnormal in the pregnant state
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==First Trimester==
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*21 y/o G1P0 at 8w0d by L=6 week US at the (WVC) presents for her OB registration appointment.
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**She denies any LOF (leaking of fluid), VB (vaginal bleeding).
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**Pt with C/C of cramping and dark “poop”, nausea and vomiting with heart burn.
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*PMH: Denied
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*PSxH: Denied
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*OB: G1
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*Gyn: Denied
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*Social Hx: Denied x 3
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*Allergies: NKDA
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*Medications: PNV (Prenatal Vitamin)
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*VS: BP: 110/80 P: 80 T: 98.6 Weight: 65Kg Height: 5’1 UA: WNL
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*PE: WNL
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*GI:
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**Constipation:
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***Mechanism: ferrous-sulfate in the pre-natal vitamins slows GI motility
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***Tx: give colace
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**Nausea and Vomiting:
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***beta-HCG (peaks 10-12 weeks)
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***progesterone: a smooth muscle relaxant; causes decreased bowel movement which can lead to increased time for water reabsorption and thus constipation
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***decreased GI motility
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**weight gain:
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***average Weight Gain
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****Normal Weight for Height: about 20 lbs
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****Underweight Women: about 30 lbs
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****Overweight Women: about 16 lbs
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==Second Trimester==
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*21 y/o is now 20 weeks pregnant
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*Presents to triage at Wishard with horrible heartburn after eating a deep fried twinkie at the state fair. 
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*She threw-up so much in early pregnancy that she is making up for it now.  She has gained 25 lbs.
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*She denied any LOF (leaking of fluid), denied VB (vaginal bleeding) or cramping.
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*She stated that she had some of the chalkie things and it didn’t make it better this time.
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*She was given a GI cocktail in triage and she was still miserable.
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*Differential Diagnosis:
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**Constipation
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***Small bowel obstruction
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**Gallstones
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**Pancreatitis
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**Appendicitis
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==First / Second Trimester GI Issues==
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*Estrogen / Progesterone Gallstones
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*Recall that progesterone is a smooth muscle relaxant.
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*Recall that progesterone is at high levels throughout pregnancy to maintain the uterine environment.
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*High circulating levels of progesterone can lead to:
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**Increased GERD from relaxation of GE sphincter
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**Constipation from delayed transit through large bowel
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**Increased N/V from delayed gastric emptying
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**“Full stomach” sensation
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*During pregnancy, the appendix is moved medially such that appendicitis pain will present mid-quadrant.
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==Second / Third Trimester GI Issues==
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*21 y/o G1P0 at 28w0d
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*Presents to triage at St. Francis Beech Grove.
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*Patient has been brought in by her family “Doc I feel horrible.  I am dizzy.  I was sitting at the high-school football game, I stood up to cheer, my heart started racing and I felt like I was going to pass-out!  My ankles are swollen and I feel horrible."
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*Denies LOF (leaking of fluid), VB (vaginal bleeding), CTXs (contractions).
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*Endorses +FM.
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*ED doctor noticed that she is breathing deeply.
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*Pertinent Vitals:
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**BP: 100/60
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**P: 90
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**T: 98.6
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**RR: 16
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**O2: 96% RA
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**Weight: 80kgs
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*Labs ordered:
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**CBC w/platelets, CXR (chest xray), ABG, UA (urinary analysis), CMP (complete metabolic panel), Coags (coagulation studies)
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What is ABG?
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*PE:
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**Lungs: CTA B
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**CV: Systolic murmur
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**Abd: Gravid, NT
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**Extrem: +1 pitting edema
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*Lab results:
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**WBC: 10, 000 (slightly elevated)
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**Hgb/HCT: 10.5/31.7% (decrease)
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**Platelets: 200,000 (slight decrease)
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**Fibrinogen: 600 (increased)
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**Bun / Cr= 3/0.6 (decreased)
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**PH: 7.44,
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**pCO2: 30
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**BiCarb: 21
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**paO2= 103
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*Are all these values normal or abnormal?
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===Blood pressure in pregnancy===
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*Pt blood pressure: 100/60
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*Both systolic and diastolic BP decrease in 2nd trimester
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*Systalic decreases 5-10 mmHg
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*Diastolic decreases 10-15 mmHg
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*Normal
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===Pulse in pregnancy===
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*Pt's pulse: 90
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*Increases 20 beats (peak at 32 weeks, middle of 3rd trimester)
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*Normal
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===Cardiac output in pregnanc===
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*Recall that cardiac output (CO) is stroke volume (SV) multiplied by the heart rate (HR).
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*CO increases at ''8 weeks'' and peaks at ''20 weeks''.
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*CO increases by 30-50%
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*CO rises to 4.5-6.0 L / min (compared to a normal of...)
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How do we know her stroke volume?
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*Systolic ejection murmur is common (90% of women).
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*S3 gallop is common (90% of women).
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*'''Peripheral vascular resistance falls during pregnancy, too.'''
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===Respiratory rate in pregnancy===
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*Recall your standard respiratory volumes (see image below).
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*'''Note that O2 demand (consumption) is increased by 15-20% in pregnancy.'''
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*These volumes are affected by the displacement of the diaphragm rostrally.
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*Note that '''respiratory rate should remain unchanged''' in normal pregnancy.
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**This is possible because the tidal volume increases (because the minute ventilation increases).
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http://www.glowm.com/resources/glowm/graphics/figures/v3/0260/004f.gif
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http://www.glowm.com/resources/glowm/graphics/figures/v3/0260/001f.gif
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*So '''dyspnea ''is'' normal with pregnancy'''.
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{|border=1
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!Volume (mL)
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!Definition
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!Non-pregnant
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!Pregnant
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!Change
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|-
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!Total lung capacity
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|Vital capacity + residual volume
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|4200
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|4000
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| -4%
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|-
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!Vital Capacity
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|Total lung capacity - residual volume
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|3200
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|3200
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| 0%
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|-
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!Inspiratory Capacity
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|Vital capacity - expiratory reserve volume
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|2500
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|2650
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| +6%
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|-
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!Tidal volume
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|Volume moved in and out with each normal breath
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|450
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|550
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| +33%
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!Expiratory Reserve Volume
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|Vital capacity - inspiratory capacity
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|700
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|550
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| -20%
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|-
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!Inspiratory Reserve Volume
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|Inspiratory capacity - total volume
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|2050
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|2050
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| 0%
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!Residual volume
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|Total volume - vital capacity
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|1000
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|800
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| -20%
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|-
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!Functional Residual Capacity
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|Residual volume + expiratory reserve volume
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|1700
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|1350
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| -20%
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|}
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===ABG in pregnanc===
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*Pt's ABG was ?
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*PH: 7.44
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*pCO2: 30
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*BiCarb: 21
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*paO2: 103
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*Acidic?
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*Basic
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*Hyperventilate?
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*Hypoventilate?
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===Respiratory System in pregnancy===
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*ABGs: PH= 7.40, PCO2=26-32, BiCarb= 18-21, PO2= 101-106
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*Pertinence: Relative Hyperventilation:
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**O2 consumption increases by 15-20%, minute ventilation increases to a greater degree
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*Pertinence: Relative Hyperventilation
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**Leading to decreased pCO2
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*Relative Respiratory Alkalosis (26-32)
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**PH is usually slightly alkaline (7.40-7.46) due to renal excretion of HCO3 (serum 18-21 (+/-) 1.6 lowers the serum bicarb)
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**Hyperventilation and increased O2 carrying capacity, pO2 is slightly elevated (106-108)
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*Pertinence: A normal pO2 in a pregnant patient is frequently abnormal
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*Changes in ABG
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{|border=1
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!Measure
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!Non-pregnant
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!Pregnant
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!Change
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!pH
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|7.38 - 7.42
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|7.4 - 7.46
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|Looser
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!pCO2 (mmHg)
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|38 - 45
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|26 - 32
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|Lower
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!pO2 (mmHg)
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|70 - 100
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|101 - 106
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|Lower
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!HCO3- (mEq / L)
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|24 - 31
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|18 - 21
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|Higher
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!O2 saturation (%)
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|95 - 100
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|95 - 100
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|None
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*Importance:
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**A normal pregnant woman has a compensated respiratory alkalosis and a diminished pulmonary reserve.
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**Respiratory Alkalosis with a compensatory metabloic acidosis.
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*Cause:
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**Progesterone
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**Diaphragm raised 4cm
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===CBC in pregnancy===
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*Plasma Volume and RBC Mass
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**Plasma volume increases by about 50%
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**RBC volume increases by about 30%
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*Result:
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**“Physiologic anemia of pregnancy”
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**The mean Hgb is about 11.5 g/dl
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===Coagulation in pregnancy===
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*In pregnancy the pt is hypercoaguable
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*Procoagulant’s are increased: I, VII, VIII, IX, X and Fibrinogen.
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*Prevents Peripartum Hemorrhage
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===Renal System in pregnancy===
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*Bun & Serum Creatinine decreases by about 25%
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*Plasma osmolarity decreases by about 10 mOsm / kg H20
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*Increase in tubal reabsorption of sodium
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*Marked increase in renin and angiotensin levels
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**But markedly reduced vascular sensitivity to their hypertensive effects
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*Increased glucose excretion
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*Anatomic:
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**Kidney size increases
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**Kidney weight increases
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**Ureteral dilation (right side greater than left side)
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**Bladder becomes an intra-abdominal organ
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*Hemodynamic:
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**GFR increase by 50%
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**Renal plasma increased by flow by 75%
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**Creatinine Clearance increases to 150-200 cc / min
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*Swollen Ankles:
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**Recall that the Plasma Volume Increases 50% in pregnancy.
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**Recall that there is decreased Systemic Vascular resistance in pregnancy.
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**Recall that there is renal retention of Na and H20 in pregnancy.
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***Leads to a total increase of 6 – 8 L in total body H20!
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***2 / 3rd extracellular
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***1 / 3rd intravascular
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***Intravascular increase is put in the "dependent" (affected by gravity) areas like the lower venous system.
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==Caring Family==
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*The patient’s husband lies her flat in an effort to keep her comfortable.
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*The fetus’s FHT’s drop to 80.
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*But, the ROCK STAR medical student wedges the patient quickly on her left side and the FHT’s recover quickly!
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*What happened?
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*Gravid Uterus placed pressure on the IVC that in turn decreased “utero-placental blood flow.”
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*Regional Blood Flow Redistribution:
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**Cardiac output falls
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**Blood is shunted '''to the brain''' and
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**Blood is shunted '''away from the uterus and placenta'''
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**This causes a ''reflex fetal bradycardia''
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==Importance of Physiology==
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*All can be abnormal in the Non-Pregnant state:
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**Decreased BP
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**Swollen ankles
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**CXR cardiomegaly with a leftward deviation
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**Systolic Ejection murmur
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**Dyspnea
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**Anemia
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**Hypercoaguable
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**NORMAL for Pregnancy
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==Maternal Physiology Review==
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http://mypage.iu.edu/~pbaenzig/medschoolfiles/icm/obgyn/Pages_from_111202_OBGYN_4_Maternal_Fetal_Physiology_Slides.png
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Current revision as of 18:11, 15 December 2013

OjTKwZ Very informative post.Really looking forward to read more.

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