Measurement of Serum Potassium Rate During Accidental Hypothermia. (Kai+)

A Comparative Study of Serum Potassium Rate Between Peripheral and Central Venous Sample Collection in Patients With Hypothermia Related Cardiac Arrest

University Grenoble Alps, Emergency Department, University Hospital Vaudois, Lausanne, Emergency Department, Hospital of Valais, Sion

Serum Potassium Rate (PR) is a key indicator for medical management of patients with accidental hypothermia particularly for hypothermia related cardiac arrest (CA). Experts recommend a cut-off value for PR of 12 mmol/l for all hypothermic victims and 8 mmol/l for avalanche casualties. Any patient presenting a PR lower than the cut-off value should be considered for Extracorporeal Rewarming. This therapeutic strategy is vital for patient survival. However, there is no consensus about what type of vessels should be punctured in order to obtain an accurate potassium rate and what type of measurement technics should be used to measure this potassium rate. The investigators hypothesize that potassium rate in these patients will differ by 1 mmol/l in blood samples collected from a peripheral vein in contrast to a central vein. The investigators study is a prospective observational, multicentre study.

blood draw from three different vessels punctured in the emergency room (central vein, peripheral vein, artery) and comparison of potassium rate and other biological values between the different sites of blood draw and two different measuring techniques (laboratory vs. blood gas analyser)

Patient in cardiac-arrest and cold exposure, diagnostic test: blood draw from three different vessels (central vein, artery, peripheral vein) and measuring of PR

Comparison of potassium rate in central venous blood and blood from a peripheral vein (measured in mmol/l)

Comparison of potassium rate from laboratory analysis and at bedside via blood gas analyser (measured in mmol/l)

Comparison of potassium rate from laboratory analysis and at bedside via blood gas analyser (measured in mmol/l)

Comparison of the time difference between laboratory analysis and blood gas analyzer at bed side (measured in minutes)

Comparison of the time difference between laboratory analysis and blood gas analyzer at bed side (measured in minutes)

Study of biological parameters to calculate the Strong Ion Gap (measured in mEq/l) according to the Stewart Approach

For each sample, the apparent strong ion difference (SIDa) will be calculated as SIDa =(Na+ +K+ +Ca2+ +Mg2+)-(Cl- +Lac-) The amount of weak plasma acid (A-) will be calculated as: A- = [Alb] × (0.123 × pH - 0.631) + [PO4] × (0.309 × pH - 0.469) The effective strong ion difference (SIDe) will be calculated as: SIDe = 1000 × 2.46 × 10-11 × PaCO2/(10-pH) + [A-] To quantify unmeasured charges, the SIG will be calculated as: SIG = SIDa - SIDe

Inclusion Criteria: Hypothermia related cardiac arrest Age > 18 years Core temperature < 30° C measured in oesophagus at hospital admission Exclusion Criteria: Age < 18 years Known condition of pregnancy or breastfeeding women Evidence of trauma-related cardiac arrest Cardiac arrest in which reanimation is not justified (frozen body, final stadium of an incurable disease, advance health care directive)

Pasquier M, Blancher M, Buse S, Boussat B, Debaty G, Kirsch M, de Riedmatten M, Schoettker P, Annecke T, Bouzat P. Intra-patient potassium variability after hypothermic cardiac arrest: a multicentre, prospective study. Scand J Trauma Resusc Emerg Med. 2019 Dec 16;27(1):113. doi: 10.1186/s13049-019-0694-3.