Cardiovascular and Respiratory Systems
Cord Blood Gases
Overview
Definitions
Normal Values
Physiology
Cases
Interventions
Review
What is a blood gas?
pH
pCO2
pO2
Bicarb
Base
pH, pCO2, pO2 are analyzed, other values are calculated
Indications: fetal distress, low Apgar
Anatomy - what goes where
ooO (photo)
Technique: cord or placenta (photo)
Normal values
for you
for a healthy term baby
(for a premature baby)
for a fetus
mean (± 2SD) pH pCO2 pO2 HCO3 BE
V: 7.35 (±0.05) 38 (±6) 29 (±6) 20 (±2) -4 (±2)
A: 7.28 (±0.05) 49 (±8) 18 (±6) 22 (±3) -4 (±2)
Acidosis
pH
pCO2
Hypoxia
Cases
Case 1
UV: 7.04 55 14 -5
UA: 7.06 53 13 -5
pH<0.04; 18% are <0.02
Case 3
UV: 7.50 20 92 -4
UA: 7.26 50 11 -5
Case 2
UV: 7.05 65 30
UA: 7.15 55 35
Case 4
UV: 6.83 100 10 16 -23
UA: 6.79 110 6 16 -25
What do you see?
What is the differential diagnosis?
19 y/o mother G2P1 Ab1, ~32 weeks by poor dates with preterm labor & diffuse abdominal pain x 4 hours
Hx: Cocaine use, last taken day of admission
Uterine contractions, q 1min, associated with repetitive late decels
Delivery by emergent C/S with 50% abruption—thick mec, 2500g baby
Apgars 1/2/4
What is the diagnosis?
UPI; Hallmark: equal arterial and venous derangements of pH, pCO2, pO2
Case 5. UV: 7.20/54/35/-7
UA: 6.96/104/35/-13
What do you see?
Ddx?
39 y/o Mother G1P1 Ab0 at 38 weeks EGA
SROM, clear fluid-mild ctrx
FHR ~140 bpm, good variability; Pitocin for FTP
severe variable decels, pit D/C’d
severe variables recurred
Terb with good recovery; variables recurred
FHR suddenly fell into 60’s
stat C/S
single tight loop, clamped, cut, removed.
Resuscitation: suctioning, stim, and very brief bag-mask PPV with 100% O2
Apgars 3/9; BW 2951g
What's the diagnosis?
Venous occlusion; Hallmark: wide difference in pH (over 0.10) and pCO2
Case 6. 20 y/o mother G3P1 Ab 1, 38 weeks in active labor
Delivery: Breech, non-pulsatile cord protruding from vagina
emergent vaginal delivery with forceps.
Male infant, Apgars 0/0/0
On further questioning, mother felt a gush of water and
“something funny near her leg” while in transit to the hospital
exact time from cord prolapse to arrival unknown (~20min)
baby UVC gas: 6.68/120/6/-30
Diagnosis?
UV: 7.24/55/20/-5
UA: 7.10/71/8/-10
What is going on?
Cord prolapse may result in occlusion of the UV or occlusion of both UV and UA’s
Occluded vessel only reflects status prior to occlusion
Case 7. UV: 7.35/48/21/-1
UA: 7.31/52/14/-1
What do you see?
Apgars 3 and 6
What's the Ddx?
HIE; Hallmark: decreased extraction, hypoxia
Case 8. 22 y/o mother G3P2 Ab0, Rh isoimmunization, early in preg, serum Rh titer 1:64
at 25 wks, developed ascites and pericardial effusion; 25mL PRBC’s Tx’d, cordocentesis
Cordocentesis at 27 and 29 weeks
At 31 wks, fetal Hct 26%
got 55mL PRBC’s through UV
brief brady, after recovery got another 20mL PRBCs
then needle became dislodged; final Hct not obtained
1 hr later: fetal tachycardia, poor variability, followed by a sudden decel to 50bpm
Emergent C/S
Apgars 2/6/7
-UV: 7.04/51/36/-18
-UA: 7.26/47/61/-6
What's going on?
Follow-up CBG: 7.33/42/41/-4
Interventions
ABC: Support maternal oxygenation and perfusion to optimize placental performance
May need to deliver the baby
Resuscitation
Ventilation
Increasing oxygen carrying capacity
Addressing underlying causes of acidosis
D: Cooling
Review
Operator Errors
Same vessel
Switched labels
Air Bubble
Pathology
Uretoplacental Insufficiency
Cord Flow Problems
Stretching
Cord Prolapse
HIE
Cordocentesis
Questions
References
Pomerance, Jeffrey, 2012 Interpreting Umbilical Cord Blood Gases: For Clinicians Caring for the Fetus Or Newborn
ACOG
NRP
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NOTES
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Case 1,2,3: Same, Switched, Bubble
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Case 4 UPI
19 y/o mother G2P1 Ab1, ~32 weeks by poor dates with preterm labor & diffuse abd pain x 4 hours
Hx: Cocaine use, last taken day of admission
Uterine contractions, q 1min, associated with repetitive late decels
Delivery by emergent C/S with 50% abruption—thick mec, 2500g baby
Apgars 1/2/4
V: 6.83/100/10/16/-23
A: 6.79/110/6/16/-25
Uretoplacental insufficiency
BE better reflects metabolic acidosis or alkalosis than bicarb
in the face of either high or low pCO2
CO2 + H20 <-> HCO3 + H
Hallmark: abnl UV values & approx equal derangements of both UV and UA
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Case 5 UVO
Impaired Cord Blood Flow
-Stretch (S)
>>short cord
>>relatively short cord-fundal implantation
>>nuchal cord or cord around another
structure (functionally short)
>>True knot (S & Compression)
>>Descent of fetus
>>Shoulder dystocia (possible)
>>Breech, trapped head (S & Compression)
Impaired Cord Blood Flow
-Compression (C)
Kinking Torsion
True Knot (S &C) Cysts
Entwining (Mo/Mo) Shoulder dystocia
Hematoma Stricture
Prolapsed cord (overt or occult)
Breech, trapped head
39 y/o Mother G1P1 Ab0 at 38 weeks EGA
SROM, clear fluid-mild ctrx-FHR ~140 bpm, good variability-Pit for FTP-severe variable decels, pit D/C’d-severe variables recurred-Terb with good recovery-variables recurred-FHR suddenly fell into 60’s-stat C/S-BW 2951g-CAN, single tight loop-clamped, cut, removed.
Resuscitation: suctioning, stim, and very brief bag-mask PPV with 100% O2
Apgars 3/9
Umbilical Vein Occlusion (UVO)
-UV: 7.20/54/35/-7
-UA: 6.96/104/35/-13 (why UA & UV needed)
>>Vein much easier to occlude then artery
-thinner muscle wall
-mean blood pressure –V:A 5/50mmHG
>>V-A pH diff- How wide is too wide?
>>Venoarterial pHs>0.10-susp UV occlusion
Hallmark of UVO: widened V-A pH and pCO2 diff
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Case 6 total occlusion
20 y/o mother G3P1 Ab 1, 38 weeks in active labor
Delivery: Breech, non-pulsatile cord protruding from vagina-emergent vaginal delivery with Piper forceps.
Male infant, Apgars 0/0/0
On further questioning, mother felt a gush of water and “something funny near her leg” while in transit to the hospital-exact time from cord prolapse to arrival unknown (~20min)
Cord Prolapse
-UV: 7.24/55/20/-5
-UA: 7.10/71/8/-10
-Apgars=0/0/0
-UVC: 6.68/120/6/-30
>>Cord prolapse may result in occlusion of the UV or occlusion of both UV and UA’s
>>Occluded vessel only reflects status prior to occlusion
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Case 7 HIE
Low Apgar Scores w/o Current Asphyxia
-UV: 7.35/48/21/-1
-UA: 7.31/52/14/-1
-Apgars=3/6
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Case 8 = 2
22 y/o mother G3P2 Ab0- 31 w 3d, Rh isoimmunization-early in preg, serum Rh titer 1:64- 23 wks, change OD, mid-zone II- 25 wks, ascites and pericardial effusion-25mL PRBC’s Tx’d, cordocentesis
Txs, cordocentesis at 27 and 29 week- 31 wks, cordocentesis- fetal Hct 26%- after 55mL PRBC’s infused through UV, brief brady- after recovery, another 20mL PRBC’s infused- needle became dislodged, final Hct not obtained- 1 hr later, fetal tachycardia with poor variability, followed by sudden decel to 50bpm- EMERGENT C/S
Apgars 2/6/7
-Follow-up CBG: 7.33/42/41/-4
Fetal Deterioration During Cordocentesis
-UV: 7.04/51/36/-18
-UA: 7.26/47/61/-6
“Corrected”
-UV: 7.26/47/61/-6
-UA: 7.04/51/36/-18
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The End