Dynamic Autoregulation is Impaired in Circulatory Shock

Abstract

Background: Circulatory shock is a life-threatening disorder that is associated with high mortality, with a state of systemic and tissue hypoperfusion that can lead to organ failure, including the brain, where altered mental state is often observed. We hypothesized that cerebral autoregulation (CA) is impaired in patients with circulatory shock. Methods: Adult patients with circulatory shock and healthy controls were included. Cerebral blood flow velocity (CBFV, transcranial Doppler ultrasound) and arterial blood pressure (BP, Finometer or intra-arterial line) were continuously recorded during 5 min in both groups. Autoregulation Index (ARI) was estimated from the CBFV response to a step change in BP, derived by transfer function analysis; ARI ≤ 4 was considered impaired CA. The relationship between organ dysfunction, assessed with the Sequential Organ Failure Assessment (SOFA) score and the ARI, was assessed with linear regression. Results: Twenty-five shock patients and 28 age-matched healthy volunteers were studied. The mean ± SD SOFA score was 10.8 ± 4.3. Shock patients compared with control subjects had lower ARI values (4.0 ± 2.1 vs. 5.9 ± 1.5, P = 0.001). Impaired CA was more common in shock patients (44.4% vs. 7.1%, P = 0.003). There was a significant inverse relationship between the ARI and the SOFA score (R = −0.63, P = 0.0008). Conclusions: These results suggest that circulatory shock is often associated with impaired CA and that the severity of CA alterations is correlated with the degree of multiple organ failure, reinforcing the need to monitor cerebral hemodynamics in patients with circulatory shock.

Cerebral Autoregulation Indices Are Not Interchangeable in Patients With Sepsis

“…A total of 95 patients (mean age 64 years old; male 74%) were eligible over the study period; APACHE II score on admission was 23 [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32], and the ICU length of stay was 6 [3][4][5][6][7][8][9][10][11][12][13][14] days. Most infections were due to bacteria (n = 66, 70%), and mostly affected the abdomen (n = 42, 44%) and the lungs (n = 26, 28%).…”

“…Beat-to-beat parameters were interpolated with a third-order polynomial and resampled at 5 Hz to generate signals with a uniform time base. The Welch method was adopted for smoothing spectral estimates obtained with the fast Fourier transform (102.4 s segments, 50% superposition) ( 15 ). An interpolation procedure was adopted to obtain ARI values (ARI = 0 indicates absent dCA, whereas ARI = 9 corresponds to the most efficient dCA) that can be observed by fitting a second-order polynomial to the integer values of ARI neighboring the region of minimum error ( 15 ).…”

“…The Welch method was adopted for smoothing spectral estimates obtained with the fast Fourier transform (102.4 s segments, 50% superposition) ( 15 ). An interpolation procedure was adopted to obtain ARI values (ARI = 0 indicates absent dCA, whereas ARI = 9 corresponds to the most efficient dCA) that can be observed by fitting a second-order polynomial to the integer values of ARI neighboring the region of minimum error ( 15 ). Objective criteria were adopted for the acceptance of estimates of ARI, using the normalized mean square error for fitting the Tiecks model ( 15 ) to the FV step response and the 95% CI for the mean coherence function in the frequency interval 0.15–0.25 Hz ( 16 ).…”

POCUS, how can we include the brain? An overview

“…Sepsis and shock patients are also other examples of critical care patients where neurological complications are common [81]. Impairment of CA has also been showed in these patients and it was demonstrated to be associated with systemic organ [82] and brain dysfunction [83]. Furthermore, a systematic review and meta-analysis reported that abnormal PI values are often observed in sepsis patients.…”

Ten Good Reasons to Practice Neuroultrasound in Critical Care Setting

“…In sepse, patients can present impaired CA. Circulatory shock patients were often associated with impairment of CA and the severity of CA alterations correlated with the degree of multiple organ failures ( 30 ).…”