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Clinical and Experimental Obstetrics & Gynecology  2020, Vol. 47 Issue (1): 79-83    DOI: 10.31083/j.ceog.2020.01.5120
Original Research Previous articles | Next articles
Fetal acidosis in a sheep model: can we perform a second day of protocol in order to reduce the numbers of animals needed?
C. Pierre1, 2, *(), L. Ghesquiere1, 2, J. De Jonckheere1, 3, E. Aubry1, 4, D. Sharma1, 4, P. Deruelle1, 2, L. Storme1, 5, V. Houfflin-Debarge1, 2, C. Garabedian1, 2
1University of Lille, EA 4489 – Perinatal Environment and Health, Lille, France
2CHU Lille, Department of Obstetrics, Lille, France
3CHU Lille, CIC-IT 1403, Lille, France
4CHU Lille, Department of Pediatric Surgery, Lille, France
5CHU Lille, Department of Neonatology, Lille, France
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Abstract  

Objective: To determine if a model of acidosis caused by occlusion of the umbilical cord could be repeated in the same sheep in ethicaly order to reduce the number of animals needed. Method: To obtain fetal acidosis, 1 min of total umbilical cord occlusion (UCO) every 2.5 min was performed on fetal sheep (n=7) until pH reached 7.10. Chronic instrumentation regularly recorded arterial blood gas and hemodynamic parameters. The occlusions were repeated to compare the data between the 2 days for each animal. Results: At the end of the UCO period, fetal acidosis was obtained with a pH 7.14 on day 1 (D1) and 7.06 on day 2 (D2). At baseline, fetuses were more hypotensive at D2 (41 mmHg vs 44 mmHg on D1, p < 0.05). During the UCO period, there was no significant difference in blood gas and hemodynamic data between D1 and D2. Conclusion: To reduce the number of animals needed, performing a second experiment on the same animal appears possible even if results must be interpreted cautiously when severe acidosis is reached.

Key words:  Fetal sheep      Animal experimentation      Animal ethics      3R      Umbilical cord occlusion      Fetal acidosis     
Published:  15 February 2020     
*Corresponding Author(s):  C. Pierre     E-mail:  clementinepierre@hotmail.com

Cite this article: 

C. Pierre, L. Ghesquiere, J. De Jonckheere, E. Aubry, D. Sharma, P. Deruelle, L. Storme, V. Houfflin-Debarge, C. Garabedian. Fetal acidosis in a sheep model: can we perform a second day of protocol in order to reduce the numbers of animals needed?. Clinical and Experimental Obstetrics & Gynecology, 2020, 47(1): 79-83.

URL: 

https://ceog.imrpress.com/EN/10.31083/j.ceog.2020.01.5120     OR     https://ceog.imrpress.com/EN/Y2020/V47/I1/79

Figure 1.  — Study periods, umbilical cord occlusions (UCO) rhythm, and fetal parameters studied (FHR, MAP).

Figure 2.  — Evolution of the fetal heart rate (FHR) according to the number of occlusions during day 1 (D1) and day 2 (D2).

Figure 3.  — Evolution of the mean arterial pressure (MAP) according to the number of occlusions during day 1 (D1) and day 2 (D2).

Table 1  — Difference between J1 and J2 on the fetal arterial blood gas parameters according to the number of occlusions.

Ground
State
Number of repeated total cord occlusions of 1 min each 2'30 min
Recovery period
6 12 18 24 30 36 42 48 54 1h
n
D1 7 7 7 7 7 7 6 5 5 5 7
D2 7 7 7 7 7 7 6 5 5 4 6
pH
D1 7, 38 (7, 37-7, 40) 7, 28* (7, 27-7, 30) 7, 19* (7, 15-7, 26) 7, 18* (7, 11-7, 25) 7, 16* (7, 07-7, 22) 7, 14* (7, 03-7, 20) 7, 15* (7, 07-7, 21) 7, 16* (7, 11-7, 20) 7, 17* (7, 10-7, 20) 7, 14*
(7, 06-7, 19)
7, 27* (7, 21-7, 27)
D2 7, 38 (7, 38-7, 40) 7, 24* (7, 21-7, 29) 7, 21* (7, 15-7, 24) 7, 18* (7, 10-7, 23) 7, 19*
(7, 09-7, 22)
7, 15* (7, 05-7, 19) 7, 15*
(7, 05-7, 20)
7, 14* (7, 04-7, 18) 7, 06* (7, 01-7, 18) 7, 06
(7, 02-7, 17)
7, 24* (7, 16-7, 31)
P02
mmHg
D1 16
(13-24)
15
(12-18)
15
(15-19)
15
(13-19)
17
(13-20)
17
(15-18)
17
(16-23)
17
(15-20)
18
(15-21)
17
(14-21)
17
(15-21)
D2 18 (17-21) 16*
(15-17)
17 (13-19) 16 (13-17) 17 (13-19) 17 (13-20) 18 (16-27) 18 (15-37) 16
(14-20)
17
(16-19)
17
(15-19)
PC02
mmHg
D1 39 (36-45) 49* (40-52) 49 (35-51) 52* (40-53) 47* (39-52) 46* (45-51) 47* (44-52) 49* (46-53) 44*
(43-48)
45*
(44-56)
40
(34-46)
D2 42 (39-43) 49* (42-56) 50* (41-55) 50 (47-53) 49* (43-51) 51* (44-54) 49 (40-53) 51 (35-52) 52*
(50-53)
53
(47-61)
44
(42-46)
Lact
mmol/l
D1 1, 05
(0, 92-1, 51)
3, 85*
(3, 01-5, 50)
5, 44*
(4, 00-8, 15)
8, 44*
(5, 56-10, 83
9, 14*
(7, 39-12, 25)
11*
(7, 19-14, 06)
10, 9*
(9, 21-15, 44)
11, 5*
(9, 59-13, 61)
11, 42*
(9, 17-13, 09)
12, 74*
(10, 78-14, 28
11*
(8, 51-13, 01)
D2 1, 13
(0, 8-1, 43)
3, 85*
(3, 76-5, 37)
6, 57*
(4, 51-8, 04)
8, 02*
(5, 12-9, 61)
8, 48*
(6, 63-11, 35)
10, 9* (7, 80-12, 97) 11*
(9, 71-12, 48)
12, 1*
(9, 58-15, 05)
11, 9*
(10, 54-15, 41)
14, 2
(12, 15-15, 68)
10, 8*
(8, 56-12, 49)
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