Plasma CO2 Removal Due to CRRT and Its Influence on Indirect Calorimetry (MECCIAS)

Universitair Ziekenhuis Brussel

Status: Completed

Conditions: CO2 Removal; Continuous Renal Replacement Therapy; Acute Renal Failure; Nutrition Poor

Treatments: Drug: NaCl predilution; Device: IC; Diagnostic Test: blood gas analysis under citrate predilution; Drug: double ultrafiltration; Diagnostic Test: evolution of vitamin and trace elements; Diagnostic Test: blood gas analysis under citrate predilution and double ultrafiltration rate; Dietary Supplement: pause and restart nutritional therapy; Diagnostic Test: blood gas analysis under NaCl predilution; Device: filter replacement

Study type: Interventional

Funder types: Other

Identifiers

NCT03314363

B.U.N. 143201731636

Details and patient eligibility

About

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.

Full description

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.

Enrollment: 10 patients

Sex: All

Ages: 18+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• AKI requiring CRRT

• Patient on CRRT who's filter you want to change

• Expected stable patient during the test ( +- 2h) evaluated at discretion of physician :

  • No alteration in medication
  • Stable respiratory settings where no change in conditions is expected. If possible, controlled mode ventilation is preferred.
  • Expected stable pH and lactate
  • no intervention will be made on patient (transport/washing/physiotherapy/...)
  • no alterations on settings of CRRT is expected to be made.

• Maximal respiratory settings: max FiO2: 60% / max inspiratory plateau pressure 30 mmHg/max tidal volumes 8ml/kg

• pH between 7,30-7,50, lactate levels <2,0

• starting settings CRRT with citrate:

  • Blood pump flow: 150 ml/min
  • Predilution ( citrate): 1500-2300ml/h
  • Dialysate dose: 25-40 ml/kg/h
  • ultrafiltration: 0-300 ml /h
  • Substitution: NaCl 300-800 ml/h or B22: 400-2000 ml/h

Exclusion criteria

• Pregnancy / lactation
• Contra-indications for the use of indirect calorimetry as stated by the AARC (FiO2>60%, chest tubes)
• Severe hemodynamic or ventilator instability.
• CRRT modalities unusual to daily clinical ICU practice

Trial design

Primary purpose: Diagnostic

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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10 participants in 1 patient group

all patients

Other group

Description:

Classic CRRT with citrate predilution

Treatment:

Dietary Supplement: pause and restart nutritional therapy

Diagnostic Test: blood gas analysis under NaCl predilution

Device: filter replacement

Diagnostic Test: blood gas analysis under citrate predilution and double ultrafiltration rate

Diagnostic Test: evolution of vitamin and trace elements

Drug: double ultrafiltration

Drug: NaCl predilution

Device: IC

Diagnostic Test: blood gas analysis under citrate predilution