PURPOSE: To determine the correlation between non invasive and invasive methods of blood pressure measurement during the first 12 hours after the onset of septic shock.
METHODS: From a prospective database of patients with severe sepsis and septic shock we identified consecutive patients who had an arterial line placed during the first 12 after the onset of septic shock. Serial blood pressure measurements recorded simultaneously at 15 minute intervals from both an arterial line and a non invasive blood pressure cuff were downloaded from the electronic information system. Based on the arterial line mean arterial blood pressure (MABP) values the data were stratified into two groups: Normotension (defined as MABP greater than 60 mm Hg) and Hypotension (MABP less than 60 mm Hg). A matched pair Bland Altman analysis was performed.
RESULTS: 83 patients with septic shock met the inclusion criteria. A total of 982 MABP measurements were analyzed, of which 319 were below <60. Bland Altman plots are presented alongside. During hypotension, noninvasive cuff pressure consistently overestimated MABP (bias -5.1, 95% CI 6.3 to 3.8 vs. 1.3, 95% CI 0.2 to 2.4, P<0.001). Correlation between cuff and arterial MABP was 0.17 during hypotension and 0.34 during normotension.
CONCLUSION: In septic shock non invasive recordings of blood pressure correlate poorly with invasive measurements and significantly overestimate MABP.
CLINICAL IMPLICATIONS: Non invasive measurement of arterial blood pressure in patients with septic shock may underestimate the severity of hypotension especially when the mean arterial pressure is below 60 mm Hg.
DISCLOSURE: Sanjay Subramanian, None.