Impact of amount of fluid for circulatory resuscitation on renal function in patients in shock: evaluating the influence of intra-abdominal pressure, renal resistive index, sublingual microcirculation and total body water measured by bio-impedance analysis on haemodynamic parameters for guidance of volume resuscitation in shock therapy: a protocol for the VoluKid pilot study–an observational clinical trial

Abstract Background All forms of shock, particularly septic shock, that involve insufficient blood supply to tissues to meet metabolic demands are main causes of morbidity and mortality worldwide and develop in one third of patients admitted to the intensive care unit (ICU). This alarmingly high incidence underlines the importance of further research in this field. Uncertainty remains about the undeceiving parameters for guidance of fluid resuscitation to avoid acute kidney injury (AKI) and renal replacement therapy. However, there are consequences of fluid overload (e.g. organ oedema and high interstitial pressures). This proposed study aims to establish a new framework of parameters for the guidance of fluid resuscitation in shock therapy focusing on the first 72 h, amending the currently used parameters (i.e. cardiac output, heart rate, blood pressure, central venous pressure) with an array of additional measurements including assessment of total body water (TBW), renal vascular resistance (renal resistive index (RRI)), intra-abdominal pressure (IAP) and microcirculatory blood flow (MBF). Methods This observational cohort study includes patients in shock presenting to the ICU. In addition to routine parameters (i.e. cardiac output, heart rate, blood pressure, central venous pressure) for volume resuscitation, MBF will be recorded using sublingual incident dark field microscopy, IAP, RRI seen in duplex-sonography and TBW will be estimated using bio-impedance analysis for correlation and eventually signalling of AKI and need for renal replacement therapy. Follow-up measurements will be taken at set intervals up to 72 h post admittance. To investigate the association between the newly investigated parameters and the occurrence of an AKI, we will compare the difference between measurements taken after admittance to the ICU and baseline values in patients with and without AKI using a two-sample t test. A linear regression model will be constructed to investigate the first and secondary outcome. Results Between January 2016 and August 2017, a total of 33 patients were recruited. The final results are expected in the second half of 2018. Conclusions The VoluKid study will investigate a new approach to assess volaemia and parameters indicating AKI in patients in shock who undergo volume resuscitation in the ICU. Trial registration The study was registered at ClinicalTrials.gov (Identifier: NCT02666404) on January 18, 2016, and at the Swiss National Clinical Trial Portal (SNCPT; Identifier: SNCTP000001693) on February 13, 2016