PMID- 18430380
OWN - NLM
STAT- MEDLINE
DCOM- 20080801
LR  - 20171001
IS  - 1701-2163 (Print)
IS  - 1701-2163 (Linking)
VI  - 30
IP  - 4
DP  - 2008 Apr
TI  - Fetal heart rate response to maternal hypocapnia and hypercapnia in late 
      gestation.
PG  - 312-316
LID - S1701-2163(16)32799-2 [pii]
LID - 10.1016/S1701-2163(16)32799-2 [doi]
AB  - OBJECTIVE: To examine the effects of acute maternal hypocapnia and hypercapnia on 
      electronic fetal heart rate (FHR) patterns in late gestation. METHODS: 
      Thirty-five women with healthy singleton pregnancies performed a modified carbon 
      dioxide (CO2) rebreathing procedure between 34 and 38 weeks of pregnancy. Prior 
      to rebreathing, subjects hyperventilated for five minutes to reduce end-tidal CO2 
      tensions (PETco2) below 23 Torr (hypocapnia). During rebreathing, PETco2 
      progressively increased from hypocapnia to hypercapnia (PETco2 = 40-60 Torr) at a 
      constant hyperoxic end-tidal O2 tension of 150 Torr. FHR responses were 
      classified using standardized guidelines over four periods: 20 minutes before 
      rebreathing (pretest), during hypocapnia and hypercapnia, and 20 minutes after 
      rebreathing (post-test). RESULTS: Mean baseline FHR measures (SD) over the four 
      test periods were 138(8), 144(10), 132(11), and 137(9) beats per minute (bpm). 
      All pairwise comparisons were statistically significant except the pretest versus 
      post-test comparison (P < 0.05, Tukey-Kramer multiple comparisons test). A single 
      tachycardia episode of 170 bpm was recorded in the post-test period. In 20 
      subjects FHR variability changed from moderate in the pretest period to minimal 
      during hypocapnia and/or hypercapnia. All but two returned to moderate FHR 
      variability in the post-test period. One other fetus with minimal post-test 
      variability had moderate values in the three preceding test periods. CONCLUSION: 
      Electronic FHR parameters remained within normal limits for third-trimester 
      fetuses with the exception of one fetus that experienced tachycardia. Acute 
      maternal hypocapnia and hypercapnia over the range studied had no adverse effects 
      on fetal well-being. These results support the safety of the modified CO2 
      rebreathing procedure for research in healthy, low-risk pregnancy.
FAU - Fraser, Derek
AU  - Fraser D
AD  - Department of Obstetrics and Gynaecology, Queen's University, Kingston ON.
FAU - Jensen, Dennis
AU  - Jensen D
AD  - School of Kinesiology and Health Studies, Clinical Exercise Physiology 
      Laboratory, Physical Education Centre, Queen's University, Kingston ON.
FAU - Wolfe, Larry A
AU  - Wolfe LA
AD  - School of Kinesiology and Health Studies, Clinical Exercise Physiology 
      Laboratory, Physical Education Centre, Queen's University, Kingston ON; Deceased.
FAU - Hahn, Philip M
AU  - Hahn PM
AD  - Department of Obstetrics and Gynaecology, Queen's University, Kingston ON.
FAU - Davies, Gregory A L
AU  - Davies GAL
AD  - Department of Obstetrics and Gynaecology, Queen's University, Kingston ON; School 
      of Kinesiology and Health Studies, Clinical Exercise Physiology Laboratory, 
      Physical Education Centre, Queen's University, Kingston ON.
LA  - eng
PT  - Comparative Study
PT  - Journal Article
PT  - Research Support, Non-U.S. Gov't
PL  - Netherlands
TA  - J Obstet Gynaecol Can
JT  - Journal of obstetrics and gynaecology Canada : JOGC = Journal d'obstetrique et 
      gynecologie du Canada : JOGC
JID - 101126664
SB  - IM
MH  - Adult
MH  - Blood Gas Analysis
MH  - Female
MH  - Gestational Age
MH  - *Heart Rate, Fetal
MH  - Humans
MH  - Hypercapnia/blood/*complications
MH  - Hypocapnia/blood/*complications
MH  - Pregnancy
MH  - Pregnancy Trimester, Third/blood
EDAT- 2008/04/24 09:00
MHDA- 2008/08/02 09:00
CRDT- 2008/04/24 09:00
PHST- 2008/04/24 09:00 [pubmed]
PHST- 2008/08/02 09:00 [medline]
PHST- 2008/04/24 09:00 [entrez]
AID - S1701-2163(16)32799-2 [pii]
AID - 10.1016/S1701-2163(16)32799-2 [doi]
PST - ppublish
SO  - J Obstet Gynaecol Can. 2008 Apr;30(4):312-316. doi: 
      10.1016/S1701-2163(16)32799-2.