I stat

Immediately following the resting ventilation measurement, a resting venous blood sample was obtained from the forearm for the measurement of hemoglobin ([Hb]) and hematocrit (Hct) both at SL and in HYP. Following the steady-state portion of the cycle endurance test, another blood sample was obtained for measurement of [Hb] and Hct. The samples were analyzed immediately in duplicate using the i-STAT portable clinical analyzer (Abbott Diagnostics, Abbott Park, IL, USA). Percent change in plasma volume (PV) from SL to HYP and from pre- to post-exercise in both SL and HYP was calculated according to the Dill equation [27 (link)].

Sampling and recording of perfusion and ventilation parameters were undertaken hourly on EVLP. Gas exchange function was measured using arterial blood gases (i-STAT, Abbott Point of Care, USA). Perfusate samples were collected for glucose and endothelial glycocalyx breakdown product analysis (10 ml was centrifuged, and the supernatant was stored at −80°C for later batch analysis). Biopsies of lung tissue were collected at 3 hrs and at completion for wet : dry weight ratio analysis.

Samples of sK⁺ were measured using central laboratory assessment and a point-of-care i-STAT device (Abbott Point of Care, Inc., Princeton, NJ, USA). All dose adjustments were based on pre-dialysis sK⁺ measured by i-STAT. Central laboratory samples were obtained throughout the study (both pre- and post-dialysis at LIDI visits, and only pre-dialysis at SIDI visits).
Prescription of dK⁺ was recorded at randomization, during dose titration and at weekly intervals during the evaluation period. For pre-dialysis sK⁺ concentrations < 4.0 mmol/L, subsequent adjustments in dK⁺ concentration could be made according to locally accepted clinical practice patterns guided by the investigator’s clinical judgment. For centers that modified dK⁺ concentration when pre-dialysis sK⁺ concentration decreased, dK⁺ concentration could be increased by 0.5 or 1.0 mmol/L if pre-dialysis sK⁺ was < 4.0 mmol/L. If dK⁺ concentration could no longer be increased during the treatment period (e.g. the dK⁺ concentration was 4.0 mmol/L), the dose of SZC could be decreased by 5 g or held if the patient was already taking the minimum dose (5 g). For sites where local clinical practice did not include increasing the dK⁺ concentration when pre-dialysis sK⁺ fell, the dose of SZC or placebo could be decreased by 5 g or held if the patient was already taking the minimum dose.