Prognostic value of brachioradialis muscle oxygen saturation index and vascular occlusion test in septic shock patients

The Prognostic Value of the Muscle Regional Oxygen Saturation Index in Patients with Acute Respiratory Distress Syndrome

Background: Impaired systemic tissue oxygenation and microvascular perfusion are associated with adverse outcomes in patients with acute respiratory distress syndrome (ARDS). Tissue oxygenation and microvascular reactivity, assessed by using near-infrared spectroscopy (NIRS), are correlated with disease severity in critically ill populations. This study aimed to detect alterations in these factors and their ability to predict outcomes in patients with ARDS. Methods: We performed NIRS measurements on the first (Day 1) and third (Day 3) days after ARDS diagnosis in 29 patients. We recorded the baseline forearm muscle oxygen saturation (StO2) and calculated the deoxygenation slope (Deoxy) and reoxygenation (Reoxy) slope. We divided the subjects into 28-day survival and non-survival subgroups to compare microcirculatory and oxygenation status differences. Results: The Day 1 StO2 values were significantly higher for the survival subgroup (60.1 ± 13.5%) than the non-survival subgroup (47.2 ± 6.9%) (p = 0.025). The ROC curve showed that Day 1 StO2 was a significant predictor of 28-day mortality (p = 0.025). There was no significant difference between the Deoxy and Reoxy slopes of the two groups (p > 0.05). The ROC of the Day 1 Reoxy slope for survival prediction (AUC0.74) was not statistically significant (p = 0.074). Conclusions: Our study showed poor survival outcomes in patients who had lower skeletal muscle StO2 values in early-stage ARDS. NIRS measurements may provide prognostic value for the survival outcomes in patients with this syndrome.

The Roles of Renal Oxygen Saturation in Septic Shock Children

Introduction

Septic shock, the most severe form of sepsis, has high morbidity and mortality rates among children. In patients with septic shock, impaired microcirculatory perfusion is associated with the severity of organ failure and the likelihood of death. Because near-infrared spectroscopy (NIRS) can assess microcirculation status and peripheral tissue oxygenation directly and noninvasively, provides real-time results, and can be performed at the patient's bedside. This study aimed to determine the prognostic value of renal oxygen saturation (rRSO2) measured by NIRS in septic shock among children.

Methods

This prospective observational study enrolled children aged 1 month to 18 years with septic shock who were treated in a pediatric intensive care unit from August 2020 to January 2021. NIRS was used to measure rRSO2 in patients diagnosed with septic shock according to the Third International Consensus Definition of Sepsis and Septic Shock. The baseline rRSO2 value (%) formed a receiver operating characteristic curve and was used to calculate the optimal cutoff value, sensitivity, specificity, and odds ratio (OR).

Results

We enrolled 24 patients, 13 nonsurvivors and 11 survivors, whose mean baseline rRSO2 values were 67.27 ± 12.95 versus 48.69 ± 16.17, respectively (P = 0.006). The optimal cutoff value for baseline rRSO2 was <60.5%, with a sensitivity of 76.9%, a specificity of 81.8%, and an area under curve 0.804 (95% confidence interval [CI]: 59.2%-98.1%, P = 0.012; OR = 15; 95 CI: 2.04-111.74).

Conclusion

Measured by NIRS, rRSO2 values are a good predictor of mortality among children with septic shock.

Muscular tissue desaturation and pneumonia in patients receiving lung cancer surgery: a cohort study

BACKGROUND

Post-operative pneumonia (POP) is a common complication of lung cancer surgery, and muscular tissue oxygenation is a root cause of post-operative complications. However, the association between muscular tissue desaturation and POP in patients receiving lung cancer surgery has not been specifically studied. This study aimed to investigate the potential use of intra-operative muscular tissue desaturation as a predictor of POP in patients undergoing lung cancer surgery.

METHODS

This cohort study enrolled patients (≥55 years) who had undergone lobectomy with one-lung ventilation. Muscular tissue oxygen saturation (SmtO 2 ) was monitored in the forearm (over the brachioradialis muscle) and upper thigh (over the quadriceps) using a tissue oximeter. The minimum SmtO 2 was the lowest intra-operative measurement at any time point. Muscular tissue desaturation was defined as a minimum baseline SmtO 2 of <80% for >15 s. The area under or above the threshold was the product of the magnitude and time of desaturation. The primary outcome was the association between intra-operative muscular tissue desaturation and POP within seven post-operative days using multivariable logistic regression. The secondary outcome was the correlation between SmtO 2 in the forearm and that in the thigh.

RESULTS

We enrolled 174 patients. The overall incidence of muscular desaturation (defined as SmtO 2 < 80% in the forearm at baseline) was approximately 47.1% (82/174). The patients with muscular desaturation had a higher incidence of pneumonia than those without desaturation (28.0% [23/82] vs. 12.0% [11/92]; P  = 0.008). The multivariable analysis revealed that muscular desaturation was associated with an increased risk of pneumonia (odds ratio: 2.995, 95% confidence interval: 1.080-8.310, P  = 0.035) after adjusting for age, American Society of Anesthesiologists status, Assess Respiratory Risk in Surgical Patients in Catalonia score, smoking, use of peripheral nerve block, propofol, and study center.

CONCLUSION

Muscular tissue desaturation, defined as a baseline SmtO 2 < 80% in the forearm, may be associated with an increased risk of POP.

TRIAL REGISTRATION

No. ChiCTR-ROC-17012627.

Near-Infrared Spectroscopy in Adult Circulatory Shock: A Systematic Review

BACKGROUND

Circulatory shock affects every third patient in intensive care units and is associated with high mortality. Near-infrared spectroscopy (NIRS) could serve as a means for monitoring tissue perfusion in circulatory shock.

PURPOSE

To assess the evidence of NIRS monitoring in circulatory shock, we conducted a systematic review of the literature.

METHODS

The study protocol was registered in International Prospective Register of Systematic Reviews (PROSPERO). We searched PubMed, Ovid MEDLINE, Scopus, and EBM Reviews databases. The reference lists of included articles, last volumes of key journals, and NIRS monitor manufacturers' webpages were searched manually. Two reviewers independently selected included studies. The quality of studies was assessed. The qualitative synthesis was guided by 3 questions: First, does NIRS monitoring improve patient-centered outcomes in adult circulatory shock patient? Second, do NIRS-derived parameters predict patient-centered outcomes, such as mortality and organ dysfunction, and third, does NIRS monitoring give additional information to guide treatment decisions?

MAIN RESULTS

Eighteen observational studies with 927 patients were included. Because of considerable clinical heterogeneity of the data, we were not able to perform a meta-analysis. Also, due to lack of randomized controlled trials, the first review question could not be answered. Based on the current review, baseline tissue oxygen saturation (StO2) however seems to predict mortality and identify patients with most severe forms of circulatory shock.

CONCLUSIONS

Near-infrared spectroscopy-derived StO2 can predict mortality in circulatory shock, but high-quality data on the impact of NIRS monitoring are lacking. Furthermore, the marked heterogeneity of the studies makes combining the results of individual studies difficult. Standardization of methodology and clinical randomized trials are needed before wider clinical use.

[Association between peripheral perfusion, microcirculation and mortality in sepsis: a systematic review]

Although increasing evidence supports the monitoring of peripheral perfusion in septic patients, no systematic review has been undertaken to explore the strength of association between poor perfusion assessed in microcirculation of peripheral tissues and mortality. A search of the most important databases was carried out to find articles published until February 2018 that met the criteria of this study using different keywords: sepsis, mortality, prognosis, microcirculation and peripheral perfusion. The inclusion criteria were studies that assessed association between peripheral perfusion/microcirculation and mortality in sepsis. The exclusion criteria adopted were: review articles, animal/pre-clinical studies, meta-analyzes, abstracts, annals of congress, editorials, letters, case-reports, duplicate and articles that did not present abstracts and/or had no text. In the 26 articles were chosen in which 2465 patients with sepsis were evaluated using at least one recognized method for monitoring peripheral perfusion. The review demonstrated a heterogeneous critically ill group with a mortality-rate between 3% and 71% (median=37% [28%-43%]). The most commonly used methods for measurement were Near-Infrared Spectroscopy (NIRS) (7 articles) and Sidestream Dark-Field (SDF) imaging (5 articles). The vascular bed most studied was the sublingual/buccal microcirculation (8 articles), followed by fingertip (4 articles). The majority of the studies (23 articles) demonstrated a clear relationship between poor peripheral perfusion and mortality. In conclusion, the diagnosis of hypoperfusion/microcirculatory abnormalities in peripheral non-vital organs was associated with increased mortality. However, additional studies must be undertaken to verify if this association can be considered a marker of the gravity or a trigger factor for organ failure in sepsis.

Impaired Muscle Oxygenation and Elevated Exercise Blood Pressure in Hypertensive Patients: Links With Vascular Stiffness

This study examined in vivo (1) skeletal muscle oxygenation and microvascular function, at rest and during handgrip exercise, and (2) their association with macrovascular function and exercise blood pressure (BP), in newly diagnosed, never-treated patients with hypertension and normotensive individuals. Ninety-one individuals (51 hypertensives and 40 normotensives) underwent office and 24-hour ambulatory BP, arterial stiffness, and central aortic BP assessment, followed by a 5-minute arterial occlusion and a 3-minute submaximal handgrip exercise. Changes in muscle oxygenated and deoxygenated hemoglobin and tissue oxygen saturation were continuously monitored by near-infrared spectroscopy and beat-by-beat BP by Finapres. Hypertensives had higher (P<0.001) central aortic BP and pulse wave velocity versus normotensives and exhibited (1) a blunted tissue oxygen saturation response during occlusion, with slower (P=0.006) deoxygenation rate, suggesting reduced muscle oxidative capacity, and (2) a slower reoxygenation rate and blunted hyperemic response (P<0.05), showing reduced microvascular reactivity. Muscle oxygenation responses were correlated with aortic systolic and pulse pressure and augmentation index (P<0.05; age and body mass index (BMI) adjusted). When exercising at the same submaximal intensity, hypertensives required a significantly greater (P<0.001) increase in BP for achieving similar muscle oxygenation levels as normotensives. This response was correlated with the magnitude of microvascular hyperemia and aortic BP. In conclusion, nontreated patients with hypertension exhibit prominent reductions in in vivo indices of skeletal muscle oxidative capacity, suggestive of mitochondrial dysfunction, and blunted muscle microvascular reactivity. These dysfunctions were associated with higher aortic systolic BP and arterial stiffness. Dysregulations in muscle oxygen delivery/utilization and microvascular stiffness, in hypertensive patients, partially contribute to their exaggerated BP during exercise.

Microcirculatory monitoring in septic patients: Where do we stand?

Microcirculatory alterations play a pivotal role in sepsis-related morbidity and mortality. However, since the microcirculation has been a "black box", current hemodynamic management of septic patients is still guided by macrocirculatory parameters. In the last decades, the development of several technologies has shed some light on microcirculatory evaluation and monitoring, and the possibility of incorporating microcirculatory variables to clinical practice no longer seems to be beyond reach. The present review provides a brief summary of the current technologies for microcirculatory evaluation, and attempts to explore the potential role and benefits of their integration to the resuscitation process in critically ill septic patients.