Critical Care

, 8:P334 | Cite as

Blood osmolar gap as a prognostic indicator in critically ill patients: preliminary results

  • S Aloizos
  • P Myrianthefs
  • V Zidianakis
  • E Tsigou
  • G Fildisis
  • S Karatzas
  • H Boutzouka
  • G Baltopoulos
Poster presentation
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Keywords

Public Health Intensive Care Unit Emergency Medicine Osmotic Pressure Prognostic Indicator 

Aim

The evaluation of the osmolar gap of incoming patients in the ICU as a prognostic indicator of outcome.

Materials and methods

The difference between measured and calculated osmotic pressure (osmolar gap) was recorded in 72 patients admitted to two medical–surgical intensive care units (ICU). The measurement took place immediately after their admission in the ICU independent of the cause of admission. The SAPS II and APACHE II scores were recorded as well as the ICU outcome. Patients were separated retrospectively into two groups on an outcome basis: A = Alive, B = Dead.

Results

The results are presented in Table 1.

Table 1

 

Group A

Group B

n

38

34

Age (years)

48.1 ± 3.5*

58.3 ± 3.7*

Sex (male/female)

26/12

27/7

Measured osmolality (mosm/l)

312.1 ± 1.8*

335.7 ± 5.8*

   Confidence interval

308.4–315.6

324.0–347.4

Calculated osmolality (mosm/l)

301.6 ± 1.9

300.9 ± 2.2

   Confidence interval

297.8–305.4

296.4–305.4

Osmolar gap

11.4 ± 1.4*

34.8 ± 5.4*

   Confidence interval

8.8–14.0

23.8–45.8

APACHE II score

21.7 ± 1.3*

25.8 ± 1.1*

SAPS II score

47.4 ± 2.6*

58.5 ± 2.7*

Days of stay in ICU

20.6 ± 3.2*

13.4 ± 2.7*

*Statistically important difference P < 0.05 between first and second column.

Conclusions

The osmolar gap calculated during admission as well as the measured osmolarity may be good indicators of the ICU mortality. Although the calculated osmolarity does not seem to be a reliable prognostic indicator in critically ill patients, it is used in the calculation of the osmolar gap, which seems to be a better prognostic indicator of the ICU mortality in comparison with the calculated osmolarity. Patients with an osmolar gap > 24 at their admission in the ICU have 53% probability of death, while patients with an osmolar gap < 14 have 28% probability of death. An osmolar gap of 35 mosm/l at admission is related with increased probability of death by 1.33 times (odds ratio), according to our preliminary results.

Copyright information

© BioMed Central Ltd. 2004

Authors and Affiliations

  • S Aloizos
    • 1
  • P Myrianthefs
    • 2
  • V Zidianakis
    • 2
  • E Tsigou
    • 2
  • G Fildisis
    • 2
  • S Karatzas
    • 2
  • H Boutzouka
    • 2
  • G Baltopoulos
    • 2
  1. 1.NIMTS HospitalHolargos-AthensGreece
  2. 2.KAT HospitalKifissiaGreece

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