Figure 1.

Isobaric hypoxic chambers and wireless recording CamDAS system. A and B, A specially designed nitrogen-generating system supplied compressed air and nitrogen to the bespoke isobaric hypoxic chambers housed at The Barcroft Centre, University of Cambridge. Each chamber was equipped with an electronic servo-controlled humidity cool steam injection system to return the appropriate humidity to the inspirate (i). Ambient partial pressures of oxygen and carbon dioxide, humidity, and temperature within each chamber were monitored via sensors (ii). For experimental procedures, each chamber had a double transfer port (iii) to internalize material and a manually operated sliding panel (iv) to bring the ewe into a position, where daily sampling of blood could be achieved through glove compartments (v). Each chamber incorporated a drinking bowl with continuous water supply and a rotating food compartment (vi) for determining food intake. A sealed transfer isolation cart could be attached to a side exit (vii) to couple chambers together for cleaning. Waste could be disposed via a sealable pipe (viii). B, A separate cohort of ewes was instrumented with the CamDAS system during surgery, allowing continuous longitudinal monitoring of arterial blood pressure and uterine blood flow. The wireless CamDAS system was contained in two parts in a custom-made sheep jacket: the data acquisition box (ix) on one side and a box containing the pressure transducers (x) on the other side. Cables (xi) provided connection between the two boxes and to 2 battery packs. Measurements made using the CamDAS system were transmitted wirelessly via Bluetooth technology (xiii) to a laptop on the outside (xii), on which it was possible to continuously measure and record uterine blood flow and maternal arterial blood pressure during the experimental period. Reproduced from Brain et al⁶ with permission. Copyright ©2015, John Wiley and Sons. Reproduced from Allison et al⁷ with permission. Copyright ©2016, John Wiley and Sons.