Evaluation of arterial blood gas measurement in managing clinically stable and mechanically ventilated multiple trauma patients in ICU

Arterial blood gas (ABG) measurement is one of the most common tests used for clinical assessment and management of multiple trauma patients under ventilator in ICU. Although this is necessary as a guide for management of these patients but it seems to be of no value in clinically stable patients and may lead to complications of blood sampling, increased hospital cost and thick medical records. In this study we evaluated the value of ABG measurement in mechanically ventilated multiple trauma patients that are otherwise clinically stable. we selected 32 clinically stable mechanically ventilated multiple trauma patients who had received FIO2=40% and had no change in vital signs, GCS and the treatment process in the past 24 hours. Vital signs [NIBP, HR, RR and Tem] and GCS of the patients were measured every hour from 24 hours prior to entering the study. In case of stable vital signs and GCS, 4 arterial blood samples, one samples every hour, were abtained for ABG measurement. At the same time the indirect BP, heart rate and Spo2 were measured by means of Pulse oximetry. 25(78.4%) patients were male and 7(21.6%) of them were female, with a mean age of 34.3 year (range 17-71 years). Based on our study the mean variation of SPO2 was 3%, with a range of 0 to 5%. The mean PH changes was 0.03% with a range of 0.02 to 0.04 unit from the baseline. The mean variations of pa02 were 16 mmHg and was in the range of -12 to 25 mmHg. PaCo2 changes were in the range of +4 to -5 (mean=2.8). The mean variation of HCO3 was 0.12 mEq/Lit with a range of +2 to -2 mEq/Lit. NIBP, HR, BP, ABGS, pH and Spo2 were variable in multiple trauma patients under mechanical ventilatory support in different times. These variations were slight and usually in the normal ranges. And there is no need for particular therapeutic interventions. Therefore we suggest physical examination as the basis of judgement and decision making in the treatment of patients. When necessary, ABG should be regarded only as a complementary measure during treatment and used to facilitate clinical judgment. ABG should not be considered as a routine test.