An interventional study of blood gas analysis under citrate predilution and filter replacement in Continuous Renal Replacement Therapy, CO2 Removal and Nutrition Poor, sponsored by Universitair Ziekenhuis Brussel. Completed at 1 site in Belgium. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2022-05-18.
Sponsored by Universitair Ziekenhuis Brussel · Not applicable, Interventional, and Diagnostic
The aim of the present study is to assess the metabolic impact of Continuous Renal Replacement Therapy and overview the obstacles and important factors compromising the use of Indirect Calorimetry in CRRT and suggest a model to overcome these issues.
Acute kidney injury (AKI) complicates a critical illness from 13% up to 78%, needing renal replacement therapy (RRT) up to10 % of all patients in the intensive care unit (ICU). Both intermittent (IRRT) and continuous renal replacement therapy (CRRT) are used. The advantage of the latter is that it has lesser influence on hemodynamics and is better tolerated in critical ill patients.
Another complication during their stay is the inability to feed themselves. Nutrition is a cornerstone in the care for the critical ill and should be started within 3 days of admission to the intensive care unit. To optimize a nutritional prescription, protein and energy targets need to be defined. Predicting formulae based on anthropometric measures and other parameters can be used to calculate the caloric need but indirect calorimetry (IC) remains the gold standard. Caloric need can be derived from Energy expenditure which is calculated with the Weir's equation using carbon dioxide (CO2) production (VCO2) and oxygen (O2) consumption (VO2). Therefore, it is underestimated if CO2 is lost through other means than the normal respiratory route. Hence one of the contra-indications of IC is CRRT.
The totalCO2 (tCO2) travels through the vascular structures within the red blood cells or inside plasma. There, most of the content has 3 different forms: as physically dissolved CO2, bicarbonate, and carbamino compounds. These compounds are in equilibrium with each other. During RRT, a potential loss of CO2 and its different forms may occur due to ultrafiltration in the dialysate. No large trials were conducted trying to quantify this loss nor identifying the determining factors which can be used to predict this loss. Indeed, one author even found a gain in tCO2 of the blood during dialysis with acetate. Trisodiumcitrate is used as an anticoagulant during CRRT. It is a weak base and due to pH change may alter the equilibrium of the Henderson-Hasselbalch equation and thus influence the balance between CO2 and HCO3- and its extraction through CRRT.
Although indirect calorimetry in the intensive care unit has been evaluated during CRRT, the loss of tCO2was not considered. The investigators explored the possibility to predict and easily calculate this CO2 exchange so IC can be used during CRRT.
Expected stable patient during the test ( +- 2h) evaluated at discretion of physician :
starting settings CRRT with citrate:
Exclusion Criteria:
Classic CRRT with citrate predilution
Diagnostic Test: blood gas analysis under citrate predilution · Device: filter replacement · Device: IC · Drug: NaCl predilution · Diagnostic Test: blood gas analysis under NaCl predilution · Drug: double ultrafiltration · Diagnostic Test: blood gas analysis under citrate predilution and double ultrafiltration rate · Dietary Supplement: pause and restart nutritional therapy · Diagnostic Test: evolution of vitamin and trace elements
blood gas analysis of blood on different sample points and dialysis fluid
Using local protocol: stop and disconnect CRRT, replace filter and reconnect and restart CRRT.
monitor patients during the whole study period with indirect calorimetry
Replace citrate predilution with NaCl
repeat blood gas analysis of blood on different sample points and dialysis fluid
double the ultrafiltration fluid by augmenting post dilution fluid and keeping ultrafiltration at the same rate.
repeat blood gas analysis of blood on different sample points and dialysis fluid
pause parenteral and enteral nutrition before indirect calorimetry is performed. and restart after first blood analysis for vitamine status
blood analysis for vitamin and trace elements. Perform this blood analysis after restart of CRRT but before restart of nutritional therapy, 30 minutes after restart of nutritional therapy and 24h after restart of nutritional therapy.
change in CO2 flow and O2 flow on different sample points of CRRT
CO2 flow and O2 flow ( ml/min) will be compared between the different sample points on CRRT with and without citrate. CO2 flow and O2 flow is calculated by multiplying fluid flow ( ml/min) on different sample points of CRRT with CO2 content or O2 content of fluid on respective sample points during CRRT with and without Citrate.
Time frame: 2hours
REE change due to CRRT
REE ( Kcal) will be measured during the whole procedure using IC. REE will be measured during CRRT. citrate wil be replaced by NaCl 0,9% fluid and REE will be measured. After this, CRRT will be stopped and REE will be measured. The difference in REE during CRRT with and without citrate and without CRRT will be calculated and compared. REE is calculated using the weir equation and VO2, VCO2. VO2 and VCO2 is calculated using FiO2, FeO2, FiCO2, FeCO2 and VE.
Time frame: 2hours
does change in CO2 flow and O2 flow on different sample points of CRRT correlate with VCO2 and VO2 change due to CRRT with or without citrate
VCO2 and VO2 change due to CRRT and due to citrate will be correlated with change in CO2 and O2 flow of fluids passing through CRRT with or without citrate.
Time frame: 2 hours
Are vitamins and trace elements sufficiently supplemented with standard nutritional therapy during CRRT
blood analysis for concentrations of Vitamin A, B1, B6, B9, B12, C, D, E ; trace elements selenium, zinc, copper, chrome; and cholesterol and triglyceride
Time frame: 24hours
VCO2 and VO2 change due to CRRT with or without citrate
VCO2 and VO2 ( ml/min) will be measured during the whole procedure using IC. VCO2 and VO2 will be measured during CRRT with citrate. citrate wil be replaced by NaCl 0,9% fluid and VCO2 and VO2 will be measured. After this, CRRT will be stopped and VCO2 and VO2 will be measured. The difference in VCO2 and VO2 during CRRT with or without citrate and without CRRT will be calculated and compared. VO2 and VCO2 is calculated using FiO2, FeO2, FiCO2, FeCO2 and VE.
Time frame: 2 hours
FiO2, FeO2, FiCO2 and FeCO2 change due to CRRT with or without citrate
FiO2, FeO2, FiCO2 and FeCO2 ( %) will be measured during the whole procedure using IC. FiO2, FeO2, FiCO2 and FeCO2 will be measured during CRRT with citrate. citrate wil be replace by NaCl0,9% fluid and FiO2, FeO2, FiCO2 and FeCO2 will be measured. After this CRRT will be stopped and FiO2, FeO2, FiCO2 and FeCO2 will be measured. The difference in FiO2, FeO2, FiCO2 and FeCO2 during CRRT with or without citrate and without CRRT will be calculated.
Time frame: 2hours
VE change due to CRRT with or without citrate
VE( ml/min) will be measured during the whole procedure using IC. VE will be measured during CRRT with citrate. citrate wil be replace by NaCl0,9% fluid and VE will be measured. After this CRRT will be stopped and VE will be measured. The difference in VE during CRRT with or without citrate and without CRRT will be calculated.
Time frame: 2hours
change in CO2 and O2 content of fluid passing through CRRT
using blood gas analyser, CO2 content and O2content ( mmol/L)of fluid on different sample points in extracorporeal circuit of CRRT with or without citrate will be analysed and compared.
Time frame: 2hours
change in bicarbonate content of fluid passing through CRRT
using blood gas analyser, bicarbonate ( mmol/L) of fluid on different sample points in extracorporeal circuit of CRRT with or without citrate will be analysed and compared.
Time frame: 2hours
change in pH change of fluid passing through CRRT
using blood gas analyser, pH of fluid on different sample points in extracorporeal circuit of CRRT with or without citrate will be analysed and compared
Time frame: 2hours
change in pCO2 and pO2 change of fluid passing through CRRT
using blood gas analyser, pCO2 and pO2 (mmHg) of fluid on different sample points in extracorporeal circuit of CRRT with or without citrate will be analysed and compared.
Time frame: 2hours
Plan to share: No
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Universitair Ziekenhuis Brussel