Clinical use of peripheral perfusion parameters in septic shock

Perfusion Index Variations in Children With Septic Shock: Single-Center Observational Cohort Study in India

OBJECTIVES

To study in children with septic shock: 1) variation in peripheral perfusion index (PI), which is a derived variable from pulse oximetry; 2) correlation between PI and lactate concentration; and 3) exploratory diagnostic evaluation between mortality and PI.

DESIGN

Prospective observational study (from October 2018 to March 2020).

SETTING

Pediatric emergency department and PICU of a tertiary hospital in India.

PATIENTS

Children (1 mo to 16 yr old) with septic shock.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Data collected included demographic, clinical, laboratory, and outcome-related variables. Hemodynamic variables like heart rate, mean arterial pressure, and PI, along with serum lactate were recorded at specified intervals. A total of 112 children with septic shock were recruited, with median (interquartile range [IQR]) age of 50 (IQR 12,118.5) months and 65 of 112 (58%) were male children. Overall mortality was 25 of 112 (22%). At admission, the median PI was 0.6 (IQR -0.30, 0.93), and we used PI less than or equal to 0.6 to define a "critical PI." Of 61 children with critical PI at admission, 26 of 61 increased above this threshold by 6 hours. We observed a negative correlation between PI and lactate, at admission ( r = -0.27; 95% CI, -0.44 to -0.08; p = 0.006) and at 6 hours ( r = -0.21; 95% CI, -0.39 to -0.02; p = 0.03). In the exploratory analysis, a PI cutoff of less than or equal to 0.6 at 6 hours had area under the receiver operating curve of 0.74 (95% CI, 0.60-0.88). That is, with a 70% sensitivity and 81% specificity for mortality, the performance of such a test in our population (pre-to-post-test probability) for mortality would be 0.22-0.51.

CONCLUSIONS

We have used pulse oximetry-derived PI in children presenting with septic shock and found that the value is negatively correlated with a rise in serum lactate concentration. However, the utility of using a critical threshold value in PI (≤ 0.6) after 6 hours of treatment to be indicative of later mortality has considerable uncertainty.

Modifications of peripheral perfusion in patients with vasopressor-dependent septic shock treated with polymyxin B-direct hemoperfusion

Abnormal peripheral perfusion (PP) worsens the prognosis of patients with septic shock. Polymyxin B-direct hemoperfusion (PMX-DHP) increases blood pressure and reduces vasopressor doses. However, the modification of PP following administration of PMX-DHP in patients with vasopressor-dependent septic shock have not yet been elucidated. A retrospective exploratory observational study was conducted in patients with septic shock treated with PMX-DHP. Pulse-amplitude index (PAI), vasoactive inotropic score (VIS), and cumulative fluid balance data were extracted at PMX-DHP initiation (T0) and after 24 (T24) and 48 (T48) h. Changes in these data were analyzed in all patients and two subgroups (abnormal PP [PAI < 1] and normal PP [PAI ≥ 1]) based on the PAI at PMX-DHP initiation. Overall, 122 patients (abnormal PP group, n = 67; normal PP group, n = 55) were evaluated. Overall and in the abnormal PP group, PAI increased significantly at T24 and T48 compared with that at T0, with a significant decrease in VIS. Cumulative 24-h fluid balance after PMX-DHP initiation was significantly higher in the abnormal PP group. PMX-DHP may be an effective intervention to improve PP in patients with abnormal PP; however, caution should be exercised as fluid requirements may differ from that of patients with normal PP.

Comparative effects of desflurane and sevoflurane on intraoperative peripheral perfusion index: a retrospective, propensity score matched, cohort study

Desflurane is known to have a larger vasodilatory effect than that of sevoflurane. However, its generalizability and effect size in actual clinical practice are yet to be proven. Patients aged ≥ 18 years who underwent noncardiac surgery under general anesthesia using inhalation anesthetics (desflurane or sevoflurane) were matched 1:1 by propensity score. The mean intraoperative perfusion index (PI) of each patient were compared between the two groups. Propensity score matching of 1680 patients in the study cohort identified 230 pairs of patients. PI was significantly higher in the desflurane group (median of paired difference, 0.45; 95% CI 0.16 to 0.74, p = 0.002). PI durations below 1.0 and 1.5 were significantly longer in the sevoflurane group. Mean arterial pressure (MAP) and durations of low MAP did not differ significantly between the two groups. Generalized linear mixed models revealed that the use of sevoflurane, mean MAP, mean heart rate, age, and duration of anesthesia had significant negative effects (lower PI), whereas mean age-adjusted minimum alveolar concentration of inhalation agent had a positive effect on PI (higher value). Intraoperative PI was significantly higher in patients administered desflurane than sevoflurane. However, the impact of the choice between desflurane and sevoflurane on intraoperative PI in this clinical setting was minimal.

INFRARED THERMOGRAPHY-BASED BODY-SURFACE THERMAL INHOMOGENEITY MONITORING TO ASSESS THE SEVERITY OF HYPOPERFUSION IN CRITICALLY ILL PATIENTS

ABSTRACT

Background: Uneven body-surface thermal distribution is a manifestation of hypoperfusion and can be quantified by infrared thermography. Our aim was to investigate whether body-surface thermal inhomogeneity could accurately evaluate the severity of patients at risk of hypoperfusion. Methods: This was a prospective cohort study in which infrared thermography images were taken from unilateral legs of critically ill patients at high risk of hypoperfusion in a cardiac surgical intensive care unit. For each patient, five body-surface thermal inhomogeneity parameters, including standard deviation (SD), kurtosis, skewness, entropy, and low-temperature area rate (LTAR), were calculated. Demographic, clinical, and thermal characteristics of deceased and living patients were compared. The risk of mortality and capillary refill time (CRT) were chosen as the primary outcome and benchmarking parameter for hypoperfusion, respectively. The area under the receiver operating characteristic curve (AUROC) was used to evaluate predictive accuracy. Results: Three hundred seventy-three patients were included, and 55 (14.7%) died during hospital stay. Of inhomogeneity parameters, SD (0.738) and LTAR (0.768) had similar AUROC to CRT (0.757) for assessing mortality risk. Besides, there was a tendency for LTAR (1%-3%-7%) and SD (0.81°C-0.88°C-0.94°C) to increase in normotensive, hypotensive, and shock patients. These thermal parameters are associated with CRT, lactate, and blood pressure. The AUROC of a combined prediction incorporating three thermal inhomogeneity parameters (SD, kurtosis, and entropy) was considerably higher at 0.866. Conclusions: Body-surface thermal inhomogeneity provided a noninvasive and accurate assessment of the severity of critically ill patients at high risk of hypoperfusion.