Changes in transcranial near-infrared spectroscopy values reflect changes in cardiac index during cardiac surgery

To determine whether changes in transcranial near-infrared spectroscopy (NIRS) values reflect changes in cardiac index (CI) in adult cardiac surgical patients. Single-center prospective post hoc analysis. University hospital. One hundred and twenty-four adult patients undergoing cardiac surgery. In each patient, several CI measurements were taken, and NIRS values were collected simultaneously. We used a hierarchical linear regression model to assess the association between NIRS values and CI. We calculated a crude model with NIRS as the only factor included, and an adjusted model, where mean arterial pressure, end-tidal CO₂ , and oxygen saturation were used as confounding factors. A total of 1301 pairs of NIRS and CI values were collected. The analysis of separate NIRS and CI pairs revealed a poor association, which was not statistically significant when adjusted with the chosen confounders. However, when the changes in NIRS from baseline or from the previous measurement were compared to those of CI, a clinically and statistically significant association between NIRS and CI was observed also in the adjusted model. Compared to the baseline and to the previous measurement, respectively, the regression coefficients with 95% confidence intervals were 0.048 (0.041-0.056) and 0.064 (0.055-0.073) in off-pump coronary artery bypass patients and 0.022 (0.016-0.029) and 0.026 (0.020-0.033) in patients who underwent cardiopulmonary bypass. In an unselected cardiac surgical population, the changes in NIRS values reflect those in CI, especially in off-pump coronary artery bypass patients. In this single-center post hoc analysis of data from a prospectively collected database of cardiac surgery patients, paired measurements of cardiac output and NIRS revealed that while there was a no correlation between individual paired measurements, a small correlation was found in changes in the two measurements from baseline values. This highlights a potential to utilize changes in NIRS from baseline to suggest changes in cardiac output in cardiac surgical populations.

Effective method of monitoring cerebral tissue oxygen saturation in cardiac surgery patients by combined use of tNIRS-1 and bispectral index

To continuously and noninvasively monitor the cerebral tissue oxygen saturation (StO₂) and hemoglobin concentration (gasHb) in cardiac surgery patients, a method combining the use of a cerebral tissue oximeter using near infrared time-resolved spectroscopy (tNIRS-1) and the bispectral index (BIS) was developed in this study. Moreover, the correlation between the estimated hemoglobin concentration (estHb), measured via tNIRS-1, and the hemoglobin concentration (gasHb), analyzed using a blood gas analyzer, were compared. The relationship between the BIS and gasHb was also examined. Through the comparison of BIS and StO₂ (r1), and estHb and gasHb (r2), the correlation between the two was clarified with maximum r1 and r2 values of 0.617 and 0.946, respectively. The relationship between BIS and gasHb (r3), showed that there was a favorable correlation with a maximum r3 value of 0.969. There was also a continuous correlation between BIS and StO₂ in patients undergoing cardiac surgery. In addition, a strong correlation was found between estHb and gasHb, and between BIS and gasHb. It was therefore concluded that the combined use of BIS and tNIRS-1 is useful to evaluate cerebral hypoxia, allowing for quick response to cerebral hypoxia and reduction of hemoglobin concentration during the operation.

Effect of desflurane on changes in regional cerebral oxygenation in patients undergoing one-lung ventilation is equivalent to the effect of propofol

OBJECTIVES

Desaturation is an important clinical problem during one-lung ventilation (OLV) since it may induce cerebral hypoxia. Measurement of cerebral oxygenation has been shown to provide accurate information about episodes of cerebral hypoxemia. The purpose of this study was to compare the effect of desflurane on changes in cerebral oxygenation during OLV with the effect of propofol.

METHODS

A randomized, single-blinded, prospective study was conducted. Fifty adult patients who were scheduled to undergo thoracic surgery were randomly assigned to anesthetic management using desflurane with remifentanil (Group D: n = 25) or using propofol and remifentanil (Group P: n = 25).

RESULTS

The characteristics of the patients were very similar. Intergroup analysis of changes in cerebral oxygenation showed no significant difference on the operative side (two-way ANOVA, F (7, 368) = 0.425, p = 0.887) or the non-operative side (two-way ANOVA, F (7, 367) = 1.342, p = 0.229). Intragroup analysis of changes in cerebral oxygenation using one-way ANOVA showed no significant difference on the operative side (Group P; p = 0.585, Group D; p = 0.928) or the non-operative side in both groups (Group P; p = 0.657, Group D; p = 0.602).

CONCLUSIONS

The effects of desflurane and propofol on changes in cerebral oxygenation in patients undergoing OLV were equivalent. Our results indicated that desflurane might be an appropriate anesthetic during OLV for maintaining cerebral oxygenation with an effective equivalent to that of propofol.

Near-Infrared Spectroscopy (NIRS) for Cerebral and Tissue Oximetry: Analysis of Evolving Applications

THE USE OF NEAR-INFRARED SPECTROSCOPY (NIRS) has increased significantly worldwide in the past decade. This technology, first described more than 40 years ago, is based on the fact that near-infrared light is able to penetrate biologic tissue and can obtain real-time, noninvasive information on tissue oxygenation and metabolism. In the clinical setting, NIRS has been able to provide clinicians potentially valuable information in patients with impaired microcirculations (systemic and cerebral). Near-infrared spectroscopy has progressed beyond assessment of brain oxygenation to monitor local tissue and muscle oxygenation and perfusion. This review analyzes the published data and provides the clinician a comprehensive account of the perioperative utility of NIRS in cardiac, vascular and thoracic surgery, as well as its increasing role in tissue/muscle oxygenation monitoring.

Outcomes of individualized goal-directed therapy based on cerebral oxygen balance in high-risk patients undergoing cardiac surgery: A randomized controlled trial

STUDY OBJECTIVE

To investigate whether optimizing individualized goal-directed therapy (GDT) based on cerebral oxygen balance in high-risk surgical patients would reduce postoperative morbidity.

DESIGN

This was a prospective, randomized, controlled study.

SETTING

The study was performed in the First Affiliated Hospital of Anhui Medical University, Hefei, China, from April 2017 to July 2018.

PATIENTS

146 high-risk adult patients undergoing valve replacements or coronary artery bypass surgery with cardiopulmonary bypass (CPB) were enrolled.

INTERVENTION

Patients were randomized to an individualized GDT group or usual care group. Individualized GDT was targeted to achieve the following goals: A less than 20% decline in the regional cerebral oxygen saturation (rScO₂) level from baseline; a less than 20% decline in the mean arterial pressure (MAP) from baseline, as well as a bispectral index (BIS) of 45-60 before and after CPB and 40-45 during CPB.

MEASUREMENTS

The primary outcome was a composite endpoint of 30-day mortality and major postoperative complications.

MAIN RESULTS

128 completed the trial and were included in the modified intention-to-treat analysis. Early morbidity was similar between the GDT (25 [39%] of 65 patients) and usual care groups (33 [53%] of 63 patients) (relative risk 0.73, 95% CI 0.50-1.08; P = 0.15). Secondary analysis showed that 75 (59%) of 128 patients achieved individual targets (irrespective of intervention) and sustained less morbidity (relative risk 3.41, 95% CI 2.19-5.31; P < 0.001).

CONCLUSIONS

In high-risk patients undergoing cardiac surgery, individualized GDT therapy did not yield better outcomes, however, the achievement of preoperative individual targets may be associated with less morbidity.

TRIAL REGISTRATION

Clinicaltrials.gov identifier: NCT03103633. Registered on 1 April 2017.

Non-invasive assessment of cerebral oxygenation: A comparison of retinal and transcranial oximetry

BACKGROUND

To investigate the correlation between cerebral (SO2-transcranial), retinal arterial (SaO2-retinal) and venous (SvO2-retinal) oxygen saturation as measured by near-infrared spectroscopy (NIRS) and retinal oximetry respectively.

METHODS

Paired retinal and cerebral oxygen saturation measurements were performed in healthy volunteers. Arterial and venous retinal oxygen saturation and diameter were measured using a non-invasive spectrophotometric retinal oximeter. Cerebral oxygen saturation was measured using near-infrared spectroscopy. Correlations between SO2-transcranial and retinal oxygen saturation and diameter measurements were assessed using Pearson correlation coefficients. Lin's concordance correlation coefficient (CCC) and Bland-Altman analysis were performed to evaluate the agreement between SO2-transcranial as measured by NIRS and as estimated using a fixed arterial:venous ratio as 0.3 x SaO2-retinal + 0.7 x SvO2-retinal. The individual relative weight of SaO2-retinal and SvO2-retinal to obtain the measured SO2-transcranial was calculated for all subjects.

RESULTS

Twenty-one healthy individuals aged 26.4 ± 2.2 years were analyzed. SO2-transcranial was positively correlated with both SaO2-retinal and SvO2-retinal (r = 0.44, p = 0.045 and r = 0.43, p = 0.049 respectively) and negatively correlated with retinal venous diameter (r = -0.51, p = 0.017). Estimated SO2-transcranial based on retinal oximetry showed a tolerance interval of (-13.70 to 14.72) and CCC of 0.46 (95% confidence interval: 0.05 to 0.73) with measured SO2-transcranial. The average relative weights of SaO2-retinal and SvO2-retinal to obtain SO2-transcranial were 0.31 ± 0.11 and 0.69 ± 0.11, respectively.

CONCLUSION

This is the first study to show the correlation between retinal and cerebral oxygen saturation, measured by NIRS and retinal oximetry. The average relative weight of arterial and venous retinal oxygen saturation to obtain the measured transcranial oxygen saturation as measured by NIRS, approximates the established arterial:venous ratio of 30:70 closely, but shows substantial inter-individual variation. These findings provide a proof of concept for the role of retinal oximetry in evaluating cerebral oxygenation.

A Protocol for Diagnosis and Management of Aortic Atherosclerosis in Cardiac Surgery Patients

In patients undergoing cardiac surgery, use of perioperative screening for aortic atherosclerosis with modified TEE (A-View method) was associated with lower postoperative mortality, but not stroke, as compared to patients operated on without such screening. At the time of clinical implementation and validation, we did not yet standardize the indications for modified TEE and the changes in patient management in the presence of aortic atherosclerosis. Therefore, we designed a protocol, which combined the diagnosis of atherosclerosis of thoracic aorta and the subsequent considerations with respect to the intraoperative management and provides a systematic approach to reduce the risk of cerebral complications.

Use of minimal invasive extracorporeal circulation in cardiac surgery: principles, definitions and potential benefits. A position paper from the Minimal invasive Extra-Corporeal Technologies international Society (MiECTiS)

Minimal invasive extracorporeal circulation (MiECC) systems have initiated important efforts within science and technology to further improve the biocompatibility of cardiopulmonary bypass components to minimize the adverse effects and improve end-organ protection. The Minimal invasive Extra-Corporeal Technologies international Society was founded to create an international forum for the exchange of ideas on clinical application and research of minimal invasive extracorporeal circulation technology. The present work is a consensus document developed to standardize the terminology and the definition of minimal invasive extracorporeal circulation technology as well as to provide recommendations for the clinical practice. The goal of this manuscript is to promote the use of MiECC systems into clinical practice as a multidisciplinary strategy involving cardiac surgeons, anaesthesiologists and perfusionists.