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
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 ------------------------------------------------------------------------------- -------------------------------------------------------------------------------
NOTES ------------------------------------------------------------------------------- ------------------------------------------------------------------------------- Case 1,2,3: Same, Switched, Bubble ------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- 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
---------------------------------------------------------------------------------------- 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 ---------------------------------------------------------------------------------------------- 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 ------------------------------------------------------------------------------- The End |
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