The use of a vascular occlusion test combined with near-infrared spectroscopy in perioperative care: a systematic review

Clinical outcomes and peripheral tissue oxygen saturation monitoring of the knee region by near-infrared spectroscopy in circulatory shock: a prospective observational cohort study

BACKGROUND

In circulatory shock, tissue hypoperfusion leads to adverse outcomes. We hypothesized that peripheral tissue oxygen saturation (StO2), measured with near-infrared spectroscopy (NIRS), could provide a non-invasive method for assessing tissue hypoperfusion and predicting pending organ dysfunction and mortality.

METHODS

ASSESS-SHOCK was a prospective, observational study enrolling circulatory shock patients from April 2019 to May 2023 in three intensive care units (ICU). Adult patients fulfilling the criteria for circulatory shock within 24 h of ICU admission were eligible. Patients underwent continuous 48 h StO2 (INVOS™) monitoring of the knee region. To express the burden of tissue hypoperfusion we calculated mean StO2 and areas below predefined StO2 thresholds. The primary outcome, change in Sequential Organ Failure Assessment (SOFA) score, was dichotomized to improvement or non-improvement in SOFA score from enrollment to day 7 or ICU discharge. Death within 7 days was considered as SOFA non-improvement. 90-day mortality was among the secondary outcomes.

RESULTS

We included 256 patients. Due to several reasons, including the COVID-19 pandemic, the patient sample was not consecutive. The median of 48-h mean StO2 was 68.3% (interquartile range [IQR] 57.5-74.1) in SOFA-improvers (n = 171), compared to 63.5% (IQR 52.7-70.8, p = 0.020) in non-improvers (n = 85), and 68.7% (IQR 58.2-74.5) in 90-day survivors, versus 60.9% (IQR 49.5-67.1, p < 0.001) in non-survivors. There were no statistically significant differences in the areas below predefined StO2 thresholds between the SOFA-improvers and non-improvers but all the areas were larger in 90-day non-survivors. The 90-day mortality was 27.0% (n = 69). In multivariable analyses 48-h mean StO2 was associated with 90-day mortality (Odds ratio [OR] 0.97, 95% confidence interval [CI 95%] 0.94-1.00, p = 0.047) but not with SOFA change. The association with mortality was, however, no longer significant in multivariable analyses after exclusion of the last 6 hours of StO2 registration in the patients (n = 29) who died during the 48 h registration (OR 0.97, CI 95% 0.94-1.00, p = 0.062).

CONCLUSIONS

Lower peripheral StO2 was associated with 90-day mortality in critically ill patients with circulatory shock but not with persisting or worsening organ dysfunction. NIRS shows promise as a non-invasive monitor of tissue perfusion in circulatory shock.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT03814564, registered 15 January 2019.

Near-infrared spectroscopy combined with vascular occlusion test to predict acute kidney injury in patients undergoing cardiac surgery: a prospective observational study

BACKGROUND

Near-infrared spectroscopy (NIRS) enables a non-invasive measurement of tissue oxygen saturation (StO2) in regions illuminated by near-infrared lights. Vascular occlusion test (VOT) serves as a model to artificially induce forearm ischemia-reperfusion. The combination of StO2 monitoring and VOT allows for dynamic evaluation of the balance between oxygen delivery and consumption in tissue, as well as the functional reserve of microcirculation. However, the implications of these measurements for patient outcomes remain inadequately understood. This study aimed to investigate the association between StO2-VOT measurements and the occurrence of postoperative acute kidney injury (AKI), in patients undergoing cardiac surgery with cardiopulmonary bypass (CPB).

METHODS

Between March 2020 and March 2021, 100 adult patients who scheduled to undergo cardiac surgery with mild hypothermic CPB were enrolled to this prospective observational study. StO2 was continuously monitored at the right forearm and ipsilateral VOT procedure was performed before initiation of CPB, at the time before weaning from CPB, and at the end of surgery. Preoperative and intraoperative factors, along with StO2-VOT parameters, were evaluated for their independent association with the occurrence of AKI following cardiac surgery. StO2-VOT parameters were also compared between patients with hyperlactatemia (peak blood lactate ≥ 4 mmol/L) and those without hyperlactatemia.

RESULTS

In our patient population (n = 87), 13.79% (12/87) patients developed AKI after surgery. Multivariable analysis revealed that CPB time and post-CPB desaturation speed (D-speed) were independently associated with AKI. Post-CPB D-speed had an area under receiver operating characteristic (ROC) curve of 0.79 (95% CI, 0.66-0.93) with a cutoff value of 0.08%·min- 1 in predicting AKI. Patients with hyperlactatemia had longer pre-CPB T1 and higher D-speed during CPB. However, ROC analysis indicated that T1 and D-speed exhibited limited predictive capacity for hyperlactatemia. Patients with AKI exhibited an increased risk of prolonged ICU stays, postoperative stroke, reoperation, and in-hospital mortality.

CONCLUSIONS

NIRS monitoring combined with VOT shows promise in predicting postoperative AKI in patients undergoing cardiac surgery with mild hypothermic CPB.

TRIAL REGISTRATION

ChiCTR1900021436 with registered date 21/02/2019.

Cerebral autoregulation, spreading depolarization, and implications for targeted therapy in brain injury and ischemia

Cerebral autoregulation is an intrinsic myogenic response of cerebral vasculature that allows for preservation of stable cerebral blood flow levels in response to changing systemic blood pressure. It is effective across a broad range of blood pressure levels through precapillary vasoconstriction and dilation. Autoregulation is difficult to directly measure and methods to indirectly ascertain cerebral autoregulation status inherently require certain assumptions. Patients with impaired cerebral autoregulation may be at risk of brain ischemia. One of the central mechanisms of ischemia in patients with metabolically compromised states is likely the triggering of spreading depolarization (SD) events and ultimately, terminal (or anoxic) depolarization. Cerebral autoregulation and SD are therefore linked when considering the risk of ischemia. In this scoping review, we will discuss the range of methods to measure cerebral autoregulation, their theoretical strengths and weaknesses, and the available clinical evidence to support their utility. We will then discuss the emerging link between impaired cerebral autoregulation and the occurrence of SD events. Such an approach offers the opportunity to better understand an individual patient's physiology and provide targeted treatments.

Noninvasive estimation of skeletal muscle oxygen consumption rate and microvascular reactivity in chronic stroke survivors using near-infrared spectroscopy

Understanding post-stroke changes in skeletal muscle oxidative metabolism and microvascular reactivity could help create therapeutic targets that optimize rehabilitative interventions. Due to disuse atrophy, we hypothesized that basal muscle oxygen consumption rate and microvascular endothelial function would be impaired in the tibialis anterior (TA) muscle of the affected leg of chronic stroke survivors compared with the nonaffected leg and versus matched controls. Fifteen chronic stroke survivors (10 females) and 15 matched controls (9 females) completed this study. A near-infrared spectroscopy oximeter measured tissue oxygen saturation (StO2) of the TA in both legs of stroke survivors and the dominant leg of controls. A cuff was placed around the thigh and inflated to 225 mmHg for 5 min while StO2 was continuously measured. The rate of change in StO2 was calculated during cuff occlusion and immediately post-cuff release. The rate of oxygen desaturation was similar between the legs of the stroke survivors (paretic -0.12 ± 0.04%·s-1 vs. nonparetic -0.16 ± 011%·s-1; P = 0.49), but the paretic leg had a reduced desaturation rate versus controls (-0.25 ± 0.18%·s-1; P = 0.007 vs. paretic leg). After cuff release, there was a greater oxygen resaturation rate in the nonparetic leg compared with the paretic leg (3.13 ± 2.08%·s-1 vs. 1.60 ± 1.11%·s-1, respectively; P = 0.01). The control leg had a similar resaturation rate versus the nonparetic leg (control = 3.41 ± 1.79%·s-1; P = 0.69) but was greater than the paretic leg (P = 0.003). The TA in the paretic leg had an impaired muscle oxygen consumption rate and reduced microvascular endothelial function compared with controls.NEW & NOTEWORTHY Secondary consequences of stroke are not well described. In this study, we show that basal muscle oxidative consumption and microvascular endothelial function are reduced in the paretic tibialis anterior muscle of chronic stroke survivors compared with matched controls using near-infrared spectroscopy and the vascular occlusion technique. There was a moderately strong correlation between microvascular endothelial function and paretic leg strength.

Assessment of Microvascular Hemodynamic Adaptations in Finger Flexors of Climbers

Climbing performance is greatly dependent on the endurance of the finger flexors which, in turn, depends on the ability to deliver and use oxygen within the muscle. Near-infrared spectroscopy (NIRS) and diffuse correlation spectroscopy (DCS) have provided new possibilities to explore these phenomena in the microvascular environment. The aim of the present study was to explore climbing-related microvascular adaptations through the comparison of the oxygen concentration and hemodynamics of the forearm between climbers and non-climber active individuals during a vascular occlusion test (VOT). Seventeen climbers and fifteen non-climbers joined the study. Through NIRS and DCS, the oxyhemoglobin (O2Hb) and deoxyhemoglobin (HHb) concentrations, tissue saturation index (TSI), and blood flow index (BFI) were obtained from the flexor digitorum profundus during the VOT. During the reactive hyperemia, climbers presented greater blood flow slopes (p = 0.043, d = 0.573), as well as greater O2Hb maximum values (p = 0.001, d = 1.263) and HHb minimum values (p = 0.009, d = 0.998), than non-climbers. The superior hemodynamics presented by climbers could indicate potential training-induced structural and functional adaptations that could enhance oxygen transportation to the muscle, and thus enhance muscle endurance and climbing performance.