title: Should capnography be used as a guide for choosing a ventilation strategy in circulatory shock caused by severe hypothermia? Observational case-series study.
abstract: BACKGROUND
  Severe accidental hypothermia can cause circulatory disturbances ranging from cardiac arrhythmias through circulatory shock to cardiac arrest. Severity of shock, pulmonary hypoperfusion and ventilation-perfusion mismatch are reflected by a discrepancy between measurements of CO2levels in end-tidal air (EtCO2) and partial CO2pressure in arterial blood (PaCO2). This disparity can pose a problem in the choice of an optimal ventilation strategy for accidental hypothermia victims, particularly in the prehospital period. We hypothesized that in severely hypothermic patients capnometry should not be used as a reliable guide to choose optimal ventilatory parameters.
  
  
  METHODS
  We undertook a pilot, observational case-series study, in which we included all consecutive patients admitted to the Severe Hypothermia Treatment Centre in Cracow, Poland for VA-ECMO in stage III hypothermia and with signs of circulatory shock. We performed serial measurements of arterial blood gases and EtCO2, core temperature, and calculated a PaCO2/EtCO2quotient.
  
  
  RESULTS
  The study population consisted of 13 consecutive patients (ten males, three females, median 60 years old). The core temperature measured in esophagus was 20.7-29.0 °C, median 25.7 °C. In extreme cases we have observed a Pa-EtCO2gradient of 35-36 mmHg. Median PaCO2/EtCO2quotient was 2.15.
  
  
  CONCLUSIONS
  Severe hypothermia seems to present an example of extremely large Pa-EtCO2gradient. EtCO2monitoring does not seem to be a reliable guide to ventilation parameters in severe hypothermia.
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland. tomekdarocha@wp.pl.|Department of Anesthesiology and Intensive Care, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland. tomekdarocha@wp.pl.|Polish Medical Air Rescue, Warsaw, Poland. tomekdarocha@wp.pl.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Darocha
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Anesthesiology and Intensive Care, Pulmonary Hospital, Zakopane, Poland Tatra Mountain Rescue Service, Zakopane, Poland.
authors.forename: Sylweriusz
authors.initials: S
authors.lastname: Kosiński
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Anesthesiology and Intensive Care, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Jarosz
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Polish Medical Air Rescue, Warsaw, Poland.|Polish Society for Mountain Medicine and Rescue, Szczyrk, Poland.
authors.forename: Paweł
authors.initials: P
authors.lastname: Podsiadło
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Anesthesiology and Intensive Care, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland.
authors.forename: Mirosław
authors.initials: M
authors.lastname: Ziętkiewicz
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Disaster Medicine and Emergency Care, Jagiellonian University Medical College, Krakow, Poland.|Department of Combat Medicine, Military Institute, Warsaw, Poland.
authors.forename: Tomasz
authors.initials: T
authors.lastname: Sanak
authors.affiliation: Polish Medical Air Rescue, Warsaw, Poland.|Department of Emergency Medical Services, Medical University of Warsaw, Warsaw, Poland.
authors.forename: Robert
authors.initials: R
authors.lastname: Gałązkowski
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Cardiac, Vascular and Transplantation Surgery, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland.
authors.forename: Jacek
authors.initials: J
authors.lastname: Piątek
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Cardiac, Vascular and Transplantation Surgery, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland.
authors.forename: Janusz
authors.initials: J
authors.lastname: Konstanty-Kalandyk
authors.affiliation: Severe Accidental Hypothermia Center, Cracow, Poland.|Department of Anesthesiology and Intensive Care, John Paul II Hospital, Jagiellonian University Medical College, Cracow, Poland.
authors.forename: Rafał
authors.initials: R
authors.lastname: Drwiła
mesh_terms: D019296:Capnography; D003097:Collateral Circulation / Q000502:physiology*; D003657:Decision Making; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D007035:Hypothermia / Q000150:complications* / Q000503:physiopathology*; D008297:Male; D008875:Middle Aged; D011044:Poland; D012121:Respiration, Artificial / Q000379:methods*; D012189:Retrospective Studies; D012720:Severity of Illness Index
keywords: Accidental hypothermia; Capnography; Pulmonary ventilation