title: Effects of continuous venovenous haemofiltration-induced cooling on global haemodynamics, splanchnic oxygen and energy balance in critically ill patients.
abstract: BACKGROUND
  A number of haemodialysis studies have demonstrated beneficial effects of cooler dialysates on global haemodynamics in chronic dialysis patients. However, the effects of continuous venovenous haemofiltration (CVVH)-induced cooling on regional perfusion and energy metabolism in critically ill septic patients have not been well defined.
  
  
  METHODS
  Nine septic mechanically ventilated patients (age 40-69 years) were investigated during CVVH (ultrafiltration 30-35 ml/kg/h). Baseline data (=WARM 1) were collected when core temperature (Tc) was >37.5 degrees C; the second data set (=COLD) was obtained after 120 min of 'cooling'; and a third set (=WARM 2) was obtained after 120 min of 'rewarming'. During 'warming' (WARM 1 and 2, respectively), both substitution fluids (SFs) and 'returned' blood (RB) were warmed (37 degrees C), whereas during 'cooling', the SFs were at 20 degrees C and RB was not warmed. We measured hepatic venous (HV) haemoglobin oxygen saturation (ShvO(2)), blood gases, lactate and pyruvate. Gastric mucosal PCO(2) (PgmCO(2)) was measured by air tonometry and the gastric mucosal - arterial PCO(2) difference (PCO(2) gap) was calculated. Haemodynamic monitoring was performed with arterial and pulmonary arterial thermodilution catheters.
  
  
  RESULTS
  Tcs were significantly altered [WARM 1, 37.9 degrees C (37.6, 38.3); COLD, 36.8 degrees C (36.3, 37.1); WARM 2, 37.5 degrees C (37.0, 38.0); P<0.001; data are median, 25th and 75th percentiles, respectively]. Systemic vascular resistance significantly increased during cooling. As a result, mean arterial pressure increased. Cooling was associated with significant decreases in heart rate, cardiac output, systemic oxygen delivery and consumption. ShvO(2) did not change [WARM 1, 51.0% (44.0, 59.5); COLD, 49.0% (42.0, 58.0); WARM 2, 51.0% (46.0, 57.0); P = NS]. The splanchnic oxygen extraction ratio, the HV lactate to pyruvate ratio, HV acid base status and PCO(2) gap remained unchanged.
  
  
  CONCLUSIONS
  Mild core cooling induced by CVVH may not affect hepatosplanchnic oxygen and energy balance in septic critically ill patients, even though it affects global haemodynamics.
authors.affiliation: ICU, Department of Internal Medicine I, School of Medicine, Charles University, Plzen, Czech Republic. rokyta@fnplzen.cz
authors.forename: Richard
authors.initials: R
authors.lastname: Rokyta
authors.forename: Martin
authors.initials: M
authors.lastname: Matejovic
authors.forename: Ales
authors.initials: A
authors.lastname: Krouzecky
authors.forename: Karel
authors.initials: K
authors.lastname: Opatrny
authors.forename: Jiri
authors.initials: J
authors.lastname: Ruzicka
authors.forename: Ivan
authors.initials: I
authors.lastname: Novak
mesh_terms: D000328:Adult; D000368:Aged; D016638:Critical Illness; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology*; D006440:Hemofiltration / Q000379:methods*; D006801:Humans; D007036:Hypothermia, Induced; D008297:Male; D008875:Middle Aged; D010101:Oxygen Consumption / Q000502:physiology*; D011446:Prospective Studies; D012121:Respiration, Artificial; D018805:Sepsis / Q000503:physiopathology / Q000628:therapy*; D013152:Splanchnic Circulation / Q000502:physiology