Table 8.
Examples of umbilical cord occlusion (UCO) studies carried out in sheep fetuses and outcomes
| Author(s) | Gestational age – GA (in days) | Number of animals | Duration of UCO (min) | Outcome | EEG | Brain histology |
|---|---|---|---|---|---|---|
| Keunen et al. (1997) | 0.6 (85–90) | 11 | 10 | Survived | Not recorded | No neuronal damage |
| 8 | 15 | Survived | ||||
| 4 | 20 | Survived | ||||
| Mallard et al. (1992) | 0.8 (120–127) | 6 | 10 | Survived | Suppressed EEG during UCO | Neuronal loss in hippocampus |
| Bennet et al. (1999) | 0.6 (89–93) | 10 | 30 | Survived | Not recorded | Not recorded, but cerebral vascular responses studied indicated cerebral injury |
| George et al. (2004) | 0.6 (90–92) | 7 | 20 | Survived |
Suppressed EEG during UCO in both In 30 min group, epileptic activity superimposed on suppressed EEG during reperfusion |
Severe brain stem injury in 30 min group but not in 20 min group |
| 10 | 30 | Survived | ||||
| Drury et al. (2014) | 0.85 (125–129) | 29 | Until mean arterial pressure (MAP) dropped to 8 mm Hg (on average 16 min of UCO) |
3 died during UCO 8 died during recovery 5 ewes entered labour, hence euthanised 13 survived until euthanised for post‐mortem |
Suppressed EEG during UCO and recovery for 3 h 13 fetuses developed status epilepticus |
Neuronal loss in cortical and subcortical regions Neuronal loss was more severe in fetuses showing status epilepticus |
| Wassink et al. (2007) | 0.6 (90–92) | 12 | 30 | Survived | Remained suppressed during occlusion. Magnitude of suppression was greater in 0.85 GA group | Not recorded |
| 0.7 (103–105) | 12 | 25 | Survived | |||
| 0.85 (124–126) | 7 | 15 | 6 out of 9 survived |