title: Hypercarbic acidosis reduces cardiac resuscitability.
abstract: METHODS
  Marked increases in myocardial hypercarbia and acidosis accompany cardiac arrest and resuscitation. To investigate whether hypercarbic acidosis independent of oxygenation is of itself detrimental to cardiac resuscitation, three groups of six Sprague-Dawley rats were ventilated with gas mixtures containing concentrations of inspired CO2 (FICO2) of 0.0, 0.3, or 0.5, with oxygen fractions held constant at 0.5. After 4 mins of ventricular fibrillation, mechanical chest compressions were initiated with a pneumatic thumper; 2 mins later, transthoracic defibrillation was attempted.
  
  
  RESULTS
  Each animal ventilated with FICO2 of 0.0 or 0.3 was successfully resuscitated. However, none of the animals ventilated with FICO2 of 0.5, in which aortic pH was less than 6.67 and aortic PCO2 was greater than 200 torr (greater than 26.7 kPa), was resuscitated (p less than .001). This finding contrasted with a second control group of seven identically treated animals which, in the absence of cardiac arrest, demonstrated no adverse effects after ventilation with an FICO2 of 0.5.
  
  
  CONCLUSIONS
  Increases in FICO2 to levels of 0.5 under conditions of constant arterial oxygenation and controlled coronary perfusion pressure preclude successful resuscitation in this rodent model of CPR.
authors.affiliation: University of Health Sciences, Chicago Medical School, IL 60064.
authors.forename: I
authors.initials: I
authors.lastname: von Planta
authors.forename: M H
authors.initials: MH
authors.lastname: Weil
authors.forename: M
authors.initials: M
authors.lastname: von Planta
authors.forename: R J
authors.initials: RJ
authors.lastname: Gazmuri
authors.forename: C
authors.initials: C
authors.lastname: Duggal
mesh_terms: D000142:Acidosis, Respiratory / Q000097:blood / Q000503:physiopathology*; D000818:Animals; D001784:Blood Gas Analysis; D002245:Carbon Dioxide / Q000008:administration & dosage; D006323:Heart Arrest / Q000097:blood / Q000503:physiopathology; D006935:Hypercapnia / Q000097:blood / Q000503:physiopathology*; D007773:Lactates / Q000097:blood; D008297:Male; D010100:Oxygen / Q000008:administration & dosage / Q000097:blood; D051381:Rats; D011919:Rats, Inbred Strains; D012151:Resuscitation
chemical_list: D007773:Lactates; D002245:Carbon Dioxide; D010100:Oxygen