week 7- PFTs & Pg Flashcards
• Info gained from PFT:
o air volume in and out of lungs o speed of air in and out o compliance: stiffness of lungs and chest wall o membrane/gas diffusion (special tests) o lung response to tx
• reasons for PFT:
o ssx of lung dz, progression
o Cough, dyspnea, cyanosis, wheezing, hyperventilation
o Monitor tx
o Eval preoperative pts
o Screen at risk for pulm dz
o Smokers, occupational exposure to toxic substances
• Primary lung volumes:
o VT: tidal; air inhaled during quiet breathing
o IRV: inspiratory reserve; max inhaled
o ERV: expiratory reserve; max exhaled
o RV: residual; remaining after max exhalation
• Lung capacities:
o = sum of primary lung vol
o TLC: total lung; sum of 4 primary vol
o VC: vital; vol exhaled from max insp to max exp
o FRC: functional residual; resting, end-expiratory vol
o IC: max vol inhaled from FRC
• How to do PFT/spirometry:
o Pt sits o Closed-circuit technique: o nose clip; breathe thru mouthpiece o deep breath as fast as possible o Blow out as hard as they can until you tell them to stop o Must do maximal insp and exp effort o Do 3x
• Normal size of lungs:
o Depends on age, gender, height, race
• FVC:
o Forced Vital Capacity: after max insp, max vol forcefully exhaled o N= 5L o =Total vol exhaled forcefully from TLC o majority can be exhaled in ↓3 s in N o ↑in obstructive dz
• FEV1
o Forced Expiratory Volume 1: Volume forcefully exhaled in 1s (from TLC)
o N= 3.75 L ( > 75-80% FVC)
o =rate of air flow as one exhales
o FEV1/FVC can characterize lung dz (N= 70-75%)
• Percent predicted FVC:
o Measured FVC/Normal FVC o Vary w age o > 80% (-120%) o 70-79%, Mild reduction o 50%-69%, Mod o ↓50%, Severe
• Percent predicted FEV1:
o >75%, Normal
o 60%-75%, Mild obstruction
o 50-59%, Mod
o ↓49%, Severe
• Flow-volume loop:
o max exp and insp flow-vol curves
o help characterize dz states (eg obstructive vs. restrictive)
o Obstruction: concave, scooped
o Restriction: ↓VC, normal shape
o Upper airway obstruction: cut-off insp/exp limbs
• Spirometry interpretation:
o 1: obstruction? = ↓FEV1/FVC (↓70%)
o 2: Interpret severity (FEV1)
o 3: Restriction: FEV1 and FVC ↓ in proportion (normal FEV1/FVC ratio)
o 4: Flow volume loops
• Normal, obstructive, restrictive PFT values:
o FVC: 5L, (4.9), (3.9)
o FEV1: 3.75L, 2.5, 3.5
o FEV1/FVC: 70-75%, 51%, 90%
o Prediclted FVC: 8-100%, >80%, 70%
• Obstructive lung dz:
o Can’t get air out o ↓: VC, IRV, ERV o ↑: RV, FRC, RV/TLC o ↓FEV1, ↓FEV1/FVC ratio o Obstructive ventilatory function: o Lumen of airways affected o Asthma & chronic bronchitis o FVC shows ↓flow rates and normal lung volumes, but with ↓FEV1
• Restrictive lung dz:
o ↓ lung compliance: lungs stiff, ↑P to expand lungs
o ↓: VC, RV, FRC, VT, TLC
o ↓FEV1, ↓FVC (N FEV1/FVC ratio)
o epithelial injury → interstitial fibrosis →stiff lung, dyspnea
o endothelial injury →abn ventilation-perfusion →Hypoxia, cyanosis
o Pulm HTN, cor pulmonale
• What is Diffusion capacity used for?
o to distinguish parenchymal and extraparenchymal causes of restriction
o Pulm: dzs like fibrosis
o Extraparenchymal: Obesity, neuromuscular dzs, chest wall deformities, large pleural effusions
• What is the diffusion capacity test?
o After PFTs, inhale trace amounts of CO
o →traverses alveolar capillary beds much more readily than CO2 or O2
o most CO is normally absorbed
o ↓: suggests pulmonary fibrosis
• Normal menstrual cycle:
o 28 d long, 1=1st day menses, 14= “normal” ovulation
o →ruptured ovarian follicle becomes corpus luteum
o → produces P → prepares uterus for fertilized ovum reception
o No fertilization → CL degenerates
o → menses ~14 d after ovulation
• Post-fertilization (pregnancy):
o Fertilization at fimbriae of fallopian tube
o Ciliated epithelial lining sweeps developing blastocyst to uterus, 5-7 d
o Implantation → Syncytiotrophoblast cells of fetal placenta make hCG
o → maintains function of ovarian CL during 1st 2 mos of pg
o → continued P production maintains pg
• Home Pg test kits, purpose:
o Measure Urinary hCG (human chorionic gonadotropin) o detected as low as 25IU o Max Sens: 1-4 d post MMP o Detects pg at very early stage o Earlier prenatal care
• hCG:
o glycoprotein
o a subunit identical to that of LH, FSH, TSH
o B subunits unique for each hormone
o Made within 24 hrs of blastocyst implantation, 7 d after conception
o 1-2 d after implantation, serum ↑ > 5 IU/L (+ serum Pg test)
o rise rapidly 1st few wks of pg: Serum levels higher than urine
o At 1 mo serum=urine
• How do home pg tests work?
o 1st hCG Abs bind hCG in urine, travel down stick
o 2nd hCG Abs bind complex (+)
o Further down stick: Anti-Ab bind to free Ab (-)
o Show up on paper
• Pt consultation for home pg tests:
o 1st AM voiding, has ↑HCG o Run test immediately o or store in fridge 24 hrs, at room temp o if (-), repeat in 7 d o still (-) → amenorrhea workup o If (+) → prenatal care follow-up
• Interpretation of home pg tests:
o (-): hCG not present at detectable concentrations
o (+): P
o False (-): Testing too early, Urine too dilute.
o False (+): Drugs: Antiparkinsonian, anticonvulsants, phenothiazines
o Medical Conditions: Tumors, Recent completed Pg or miscarriage
• Accuracy of home pg tests:
o 97% sens
o 95% spec
o similar to lab tests: User and technique dependent
• quant serum hCG:
o usu monoclonal Abs against B subunit of HCG
o (+) 1-2 d after implantation, or 8-9 d after conception
o double every 48 hrs in 1st tri
o higher w multiple embryos
• quant serum hCG by weeks gestation:
o serial serum hCG tests eval pg integrity o 1: 5-50 IU/L o 2: 50-500 o 3: 100-10,000 o 4: 1,080-30,000 o 6-8: 3,500-115,000 o 12: 12,000-270,000 o 13-16: Up to 200,000 o 17-40: Gradual fall to 4,000
• hCG w Ectopic pg:
o 17/1000 pg’s in US
o ↓ rate of ↑serum HCG
o Suspect if ↓66% ↑in 48 hrs
o ↓ than expected for GA (gestational age)
o remove ectopic tissue → HCG return to ↓5 IU/L in 4 wks
• other reasons for ↓ hCG levels:
o diminished viability of placenta
o Threatened miscarriage
o Fetal demise
o Spontaneous miscarriage in 30% all Pg’s, uss early 1st tri
• Pre-natal testing:
o Pre-Natal Panel o Pap test o GC/CT o GDM Testing o Repeat Ab Screen on Rh (-) moms o Vag Group B Strep testing o “Triple Screen” / “Quad Screen” o Pre-eclampsia testing o HSV testing
• Labs on 1st pre-natal visit:
o CBC o Blood gp & Ab screen o HBsAg o Rubella Ab o VDRL o Urine testing o PAP smear o In high risk population: Chlamydia swab, TFT o HIV (opt-out, not op-in), redarless of risk
• Blood typing:
o If O, IgG a-A & a-B can cross placenta → HDN (54/1000)
o If Rh (-) → type father
o If fetus Rh (+), mon can be sensitized, form anti-D
o Affects future pregnancies
o Prevent w Rhogam (Rh immune globulin), inj at 28 wks and at birth
• 1st pg HDN:
o “Unexpected” Abs can cross placenta → HDN
o Ab’s like: a-E, a-Kell, a-Duffy etc…
o HDN dt these Abs can occur in 1st pg
• CBC, ferritin:
o screen for abn, mainly anemia or infx
o RBC, Hgb, Hct all ↓ in anemia
o RBC indices to classify anemia, indicate tx
o WBC & differential ct should be normal (may see ↑WBC)
o Plt ct should be normal to avoid abn bleeding during delivery
o Ferritin: baseline iron stores
• Urinalysis:
o Screen for abn and infx
o Renal: SG, protein, RECs, RBC, casts
o Metabolic: Glucose, ketones, urobilinogen, bilirubin
o Microbial: Leukocyte esterase, nitrites, bacteria
• HBsAg:
o Identify infx mothers
o Inc 5 wks to 6 mos, so mb (-) if recent exposure
o →may run Anti-HBc IgM to see if acute, or HBeAg
o If (-): mb vaccination in 2nd tri to protect fetus as a precaution
o If (+): HB Ig in 12 hrs of birth prevents 70% chronic HBV in infants
o CDC recommends Vaccination of infant
• GC/CT:
o Both can cause PID, salpingitis, sterility
o OR infant neonatal conjunctivitis; Chlamydial or Gonorrheal ophthalmia
o Chlamydia infx: 10-20% infants →Chlamydial pneumonia
• What are Teratogens?
o may cause birth defects or alt normal fxn when present in utero
o Timing is critical: teratogenic only when exposure takes place during a critical time period
o Mechanisms are agent specific w characteristic abnormalities
o Severity depends on dose, timing, genetic susceptibility, interactions w other exposures
o For most agents, limited information is available; usu animal studies and few case reports
• Established teratogens:
o Some Maternal Dzs: DM, SLE, Graves, hypothyroid o Ionizing radiation o Some Maternal Infx (TORCH) o Certain Drugs o Alcohol
• TORCH
o T- toxoplasmosis o O – other such as varicella zoster, syphilis, parvovirus o R - rubella o C - CMV o H – herpes or HIV
• Rubella titer:
o Women susceptible to Rubella have low serum titer ↓10 IU/mL
o should test prior to pg, so can get vaccinated at least 28 d prior to conceiving (mb 3 mos)
o Congenital rubella infxn in 1st tri: Heart defects, Brain damage, mental retardation, Deafness, Spontaneous miscarriage, Stillbirth
o 1st rubella infx: LA, maculopapular rash, ↓fever
• Toxoplasmosis Abs:
o Need Ab titer, since infx usu asx
o Presence of Abs ensures protection against congenital toxoplasmosis
o Fetal infx: if mother acquires toxoplasmosis after conception
o Classic triad of congenital toxoplasmosis: hydrocephalus, intracranial calcifications, chronic retinitis
• STS Screen: RPR/VDRL
o (+) 2 wks after inoculation w Treponema
o (+) in most 1st & 2nd, but only 2/3 3rd syphilis
o Confirm: FTA/ABS or MHA-TP
o Untx syphilis may cause abortion, stillbirth, premature labor
o Fetal effects: CNS damage, hearing loss, Hutchinson’s teeth, death
• HIV:
o now “opt out”
o No longer requires submission of form signed by pt and physician
o ELISA: 99% sens w HIV > 12 wks
o Confirm w Western Blot.
o p24 Ag detectable earlier, 2-6 wks after infx
• Biochemical Changes during Pregnancy
o Early pg ↑BV can “dilute” Hgb, HCT, BUN, Creatinine, albumin
o often → ↑BG after wk 24. Mb dt ↑insulin resistance or insufficient pancreatic output
o BUN may ↑ dt ↑ protein intake
o If get HTN after wk 20, ↑BUN may reflect renal insufficiency
o ↑Chol & Tg: liver production dt hormonal variations
o ↑ALP, placental isoenzyme form.
o Fetal liver & yolk sac: Alpha-fetoprotein
o Placenta: hCG, E3, Inhibin A. assess risk of Neural Tube Defects and Trisomies 18 & 21
• 2nd tri test:
o Triple Screen and Quad Screen:
o assess risk of Neural Tube Defects, Down Syndrome/Trisomy 21 & 18
o Risk Down ↑ in F > 35, but 80% kids w Down, mom is ↓35
o “Triple Screen” based on maternal AFP, unconjugated E3 & hCG at 16-18 wks
o “Quad Screen” Adds maternal serum Inhibin A to improve detection of Down and ↓ false (+)
• Triple / Quad Screen interpretation
o Samples for testing must include: fetus GA, mom age, race, wt, # previous pg’s, if insulin-dependent DM
o → calc “Multiples of the Median” (MoM), assess risk of defects
o dx requires amniocentesis or chorionic villus sampling
o ↑AFP mc dt underestimation of fetal GA
o AFP mb ↑ if mult pg’s??
o ↓ Unconjugated E3 also occurs in fetal distress
• Triple screen:
o Analytes used: AFP, uE3, B-hCG o Values vary by lab o 5% screen-(+) rate: o Down’s: 60-70% o Trisomy 18: 60% o NTD: 75-80%
• Quad screen:
o Use instead of triple when vailable and covered by insurance
o AFP, uE3, B-hCG, + dimeric inhibin-A (DIA)
o 5% screen (+) rate:
o Down’s: 75-80%
o Trisomy 18: 60%
o NTD: 75-80%
• Abn Analyte results for AFP, uE3, hCG, Inhibin A
o NTD: ↑ AFP
o Down: AFP & uE3↓30%+; hCG & inhibin A↑2x+
o Trisomy 18: ↓ all, uE3 best indicator
• Aneuploidy:
o Cell free testing
• GDM, screen:
o 3-12 % of pg’s
o dt insulin resistance or insufficient pancreatic output of insulin
o Screen: at 24-28 wks
o Mom drinks 50g glucose load, Blood drawn at 1 hr
o If glucose > 140 mg/dL → 3-hr OGGT
o Only 15% with + screen actually have GDM
• GDM OGGT test:
o overnight fast, FBS
o Mom drinks 100g glucose load
o Blood drawn hourly for 3 hrs
o GDM cut-off levels: Fasting > 105 mg/dL, 1-hr > 190 , 2-hr > 165, 3-hr > 145
o Dx, any of 3 criteria: fasting > 105, any 2 hourly values > cutoffs, any value > 200 mg/dL
• Urine dips during pg:
o Usu in-office to check for glucose, protein, UTI at every PN visit
• 3rd tri test:
o Group B Strep Infx Screen: in vagor rectum, 25% all healthy, adult women
o swabbing vag and rectal areas @ 35-37 wks
o (+) means carrier, not necessarily active infx
o may pass infx to baby during delivery
o Prophylactic abx if:
o Premature Labor (37 wks)
o PROM, 18+ hrs
o Fever during labor
o UTI (dt GBS) during pg
o A previous delivery resulted in a baby w GBS
• Nitrazine paper:
o determine if watery d/c of gravida is vag secretion or amniotic fluid
o Vag: usu acid pH 4.5-5.5
o Ammonic fluid: alkaline pH 7.0-7.5
o AF means PROM
• Blood neonatal tests:
o ABO, Rh, Direct Coombs (DAT)
o ABO blood group always determined on babies of O moms
o Rh w Rh (-) mom
o Give Rhogam if needed
o DAT on babies in above categories, or any case of neonatal jaundice
• Neonatal jaundice:
o when liver is immature, no enzymes for bilirubin conjugation
o Bilirubin: Total and direct
o Clinical: total bilirubin > 2.5 mg/dl
o ↑unconjugated (indirect) bilirubin, can pass through BBB deposits in brain cells
o Total bilirubin must be ↓ 15 mg/dl to avoid kernicterus and developmental disabilities
• NW regional newborn screening, & Oregon:
o all infants in US screened for 29 recommended conditions
o Incidence of all the blood spot conditions is now one infant in 1000 or 45–50 new cases/yr in Oregon (~1 infant/wk)
o Oregon: Heelstick: Sickle cell anemia & trait; Biotinidase deficiency; Galactosemia, etc
• What is PKU
o AR, 1:14000
o = def phenylalanine hydroxylase, converts phenylalanine to tyrosine (→neurotransmitters, pigment)
o PKU= accum phenylalanine and metabolites, deposit in brain → brain damage
o Phenylpyruvic acid builds up and spills into urine
• What is the PKU test?
o =Guthrie test
o Heelstick, 3 d after birth
o preferably after infant has been fed milk (phenylalanine in milk)
o (+) → blood phenylalanine test
o (+): need to avoid phenylalanine in diet
o urine PKU done at 6 wks if blood test done in hospital
• What can obscure the PKU test?
o Premies may have false (+) dt ↓ phenylalanine hydroxylase
o Test mb invalid if not eating well or weighs ↓5 lbs
• T4/thyroxine neonate test:
o screened for T4 at same time as PKU
o At 3 d normal infant T4 is 11-22 mg/dL
o T4 reaches adult levels at 7-10 d
o Congenital Cretinism: Intellectual disability dt ↓T4
o can be avoided by tx hypothyroidism shortly after birth
• HTN during pg:
o mc medical problem during pg (8%)
o 4 categories: Chronic, Pregnancy Induced, Preeclampsia-eclampsia, Preeclampsia superimposed on chronic HTN
o HTN in pg → maternal and fetal morbidity
o a leading source of maternal mortality
• pg-induced HTN:
o Usu mild and later in pg
o No renal or other systemic involvement
o Resolves 12 wks postpartum
o May become preeclampsia
• Preeclampsia, etio:
o New onset HTN, After 20 wks gestation, or Early post-partum, previously normotensive
o Resolves in 48 hrs postpartum
o 2-6% in primigravid
o 20-25% w hx chronic HTN
o Etio: Unk mech; mb Immune, genetic, Placental ischemia
o Other: Endothelial dysfxn, Vasospasm
o Hyper-response to vasoactive hormones (eg angiotensin II & Epi)
• Ssx of preeclampsia:
o Renal/systemic ssx:
o Proteinuria > 300 mg/24hr
o Oliguria or Serum-plasma creatinine ratio > 0.09 mmol/L
o HA w hyperreflexia, eclampsia, clonus, visual disturbances
o ↑ LFTs, glutathione-S-Transferase alpha 1-1, ALT, or R abn pain
o Thrombocytopenia, ↑ LDH, hemolysis, DIC
o pathologic capillary leak → rapid weight gain, edema of face, hands, pulm edema, hemoconcentration
o fetal/placental tissue: dysfxn of mult organ systems
• maternal risk factors for preeclampsia:
o 1st pg o ↓ 18 or > 35 o hx preeclampsia, FHx o Black race o chronic HTN, renal dz, DM, anti-PL syndrome o Twins
• Mild vs severe preeclampsia:
o Systolic: 140-160; >160 o Diastolic: 90-110; >110 o Urine protein: ↓5g, dip +1-2; >5g, +3-4 o Urine output: >500 mL/d; ↓500 o HA: no; yes o Visual disturb: no; yes o Epigastric pn: no; yes
