title: Urinary PCO2 for hemodynamically unstable patients.
abstract: BACKGROUND
  Gastric intramural pH (pHi) derived from gastric PCO2 has been successfully used to assess splanchnic ischemia for patients with unstable hemodynamics, but with some limitations. Urinary bladder, also an easily accessible hollow viscus, should provide as a useful route for the same purpose. However, no study has used urinary PCO2 to evaluate the adequacy of perfusion in critically ill patients.
  
  
  METHODS
  Fifty patients admitted to intensive care unit were included and divided into hemodynamically stable and unstable groups. Several parameters such as arterial pressure, dopamine dosage, heart rate, serum lactate, arterial blood gas, urinary PCO2, and concentrations of Na, K and Cl in urine were measured. Patients with some other renal or pre-renal conditions that might affect urinary PCO2 were excluded.
  
  
  RESULTS
  Urinary PCO2 was markedly higher (78.6 +/- 9.9 vs. 43.1 +/- 1.7 mmHg, p < 0.0001) in unstable group. Serum anion gap level, dopamine dosage and heart rate were significantly higher and PaO2/FiO2 ratio as well as mean arterial pressure was lower in unstable group. Serum lactate, arterial pH and other parameters failed to distinguish between groups. Dopamine dosage significantly correlated with urinary PCO2 (r = 0.5357, p = 0.0149) in unstable group.
  
  
  CONCLUSIONS
  With careful selection of patients, urinary PCO2 can effectively differentiate hemodynamically unstable patients from stable ones. It also correlates significantly with dopamine dosage in patients with unstable hemodynamics.
authors.affiliation: Department of Respiratory Therapy, Veterans General Hospital-Taipei, Taiwan, R.O.C.
authors.forename: M S
authors.initials: MS
authors.lastname: Lin
authors.forename: T C
authors.initials: TC
authors.lastname: Lien
authors.forename: W C
authors.initials: WC
authors.lastname: Yang
authors.forename: S C
authors.initials: SC
authors.lastname: Wu
authors.forename: W W
authors.initials: WW
authors.lastname: Tsai
authors.forename: J H
authors.initials: JH
authors.lastname: Wang
mesh_terms: D000368:Aged; D002245:Carbon Dioxide / Q000652:urine*; D002318:Cardiovascular Diseases / Q000175:diagnosis* / Q000503:physiopathology; D016638:Critical Illness; D005260:Female; D006439:Hemodynamics; D006801:Humans; D008297:Male; D008875:Middle Aged; D010313:Partial Pressure; D011237:Predictive Value of Tests; D011446:Prospective Studies
chemical_list: D002245:Carbon Dioxide