[Impairment of oxygenation of patients in surgical intensive care : Early symptom of severe sepsis].

BACKGROUND: Sepsis and septic shock are major contributors to morbidity and mortality in intensive care patients. Early identification and adequate therapy are of utmost importance to reduce the still high mortality in patients with severe sepsis. Many of the pathophysiologic changes are nonspecific. Thus, a combination of symptoms and laboratory results are necessary to confirm the diagnosis. Impairment of the Horovitz index is identified as being a primal prognostic criterion for early diagnosis in serious progression of sepsis, after exclusion of a few differential diagnoses. Based on this fact, the prevalence of this symptom compared to other sepsis parameters is of specific interest.
METHOD: In a retrospective study 33 cases of serious sepsis were analysed during the patient's course of intensive care treatment focusing on oxygenation. The deterioration of oxygenation, meaning a drop in the Horovitz index below 200 mm Hg (25.7 kPa) or a decrease in paO2 by 67.5 mm Hg (9 kPa) in spontaneously breathing patients with sepsis was the mean inclusion criteria. We compared the sequence of occurrence of known sepsis markers (e. g. PCT, WBC, CRP) with the deterioration in oxygenation to answer the question whether impairment of oxygenation could be an early symptom of severe sepsis. The Mann Whitney U‑test and a discriminant analysis were performed to verify differences of the variables investigated between surviving and deceased patients. Furthermore a regression analysis was performed to confirm the results of the discriminant analysis.
RESULTS: The mean drop in the Horovitz index was 90 ± 24 mm Hg (12 ± 3.2 kPa) within 4.5 h respectively. This was highly significant (p < 0.001). In all patients impairment of oxygenation indicated an individual onset and further progression of a serious sepsis. In more than ¾ of all cases this symptom occurred in an earlier stage than other organ dysfunctions. In 79 % of cases, patients showed an impairment of oxygenation before PCT increased on values of >2 ng/ml. In 76 % of cases impairment of oxygenation occurred earlier than all other investigated parameters. Significant differences were found between surviving and deceased patients regarding to their age as well as the timeframe from the beginning of impaired oxygenation to the onset of the effect of the administered antibiotics. These two parameters (age, time to sufficient antibiotic therapy) were confirmed by regression analysis and showing similar effect coefficients, age 1.09 and time to sufficient antibiotic therapy 1.04 respectively.
CONCLUSION: An urgent worsening of pulmonary function in patients in intensive care requires immediate differential diagnostics due to substantial therapeutic consequences. Our results confirm that impairment of pulmonary oxygenation is the first prognostic symptom of severe onset of sepsis. Consequently, we recommend that this parameter be considered in diagnostic staging. After exclusion of a few differential diagnoses impairment of oxygenation can be the very first symptom of severe sepsis. The patient's age and time to sufficient antibiotic therapy are two very important prognostic factors with respect to mortality. Early and sufficient antibiotic therapy, and in a few cases surgical intervention are of utmost importance.