Near-infrared Spectroscopy Monitoring Research Articles

Cerebral perfusion responses to active standing are attenuated in patients with vasovagal syncope

Abstract Funding Acknowledgements Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Irish Research Council (IRC): Government of Ireland Postgraduate Scholarship Programme 2018, Dublin, Ireland Fundació Universitària Agustí Pedro i Pons, Universitat de Barcelona, Barcelona, Spain Background Syncope is a transient loss of consciousness due to cerebral hypoperfusion. While traditionally peripheral haemodynamics are monitored during clinical assessment of syncope, relatively little is known about cerebrovascular haemodynamics during orthostasis in patients with syncope. Purpose Here we investigated whether young patients with syncope present an altered cerebral perfusion when compared to healthy controls. Given potential hyper-reactivity of the autonomic nervous system previously reported in these patients, we hypothesise that an overly active cerebral autoregulation will be present in patients with syncope. Methods Consecutive patients were prospectively recruited from a National Falls and Syncope Unit, and a convenience sample of young healthy community dwelling adults was recruited from a local university (16-30 years). Participants performed a 3 minute active stand test with continuous measurement of beat-to-beat peripheral haemodynamics (blood pressure (BP), heart rate (HR)) and changes in concentration of oxygenated Δ[O2Hb] and deoxygenated Δ[HHb] haemoglobin were derived from a near-infrared spectroscopy (NIRS) monitor. Baseline, steady state and other time domain features were derived for Δ[O2Hb] (nadir, overshoot, overshoot-to-nadir, overshoot-to-nadir recovery rate) and Δ[HHb] (peak, trough, peak-to-trough, peak-to-trough recovery rate) and multiple linear regression was used to compare differences between the two groups correcting for covariates (p < 0.05 significant). Results Patients (n = 40) were younger (20(5.5) vs 23(1) years, p = 0.003) than controls (n = 17) and were well matched in gender, weight, height, BMI and resting haemodynamics. Patients had a smaller Δ[O2Hb] overshoot-to-nadir difference (β: -0.749, CI:(-1.593 0.094), p = 0.08), a slower Δ[O2Hb] recovery rate (β: -0.186, CI:(-0.388 0.016), p = 0.071), and smaller Δ[HHb] peak-to-trough difference (β: -0.530, CI:( -0.921 0.138), p = 0.018) and slower Δ[HHb] recovery rate (β: -0.151, CI: (0.244 0.057), p = 0.008). Conclusion Patients with syncope had signs of an attenuated cerebral oxygenation response to an AS when compared to controls. We hypothesise that this is due to hyper-reactive cerebral autoregulation mechanism, which might be related to a hyper-sensitive autonomic system. Furthering our understanding of vasovagal syncope physiology can help inform future interventions and treatments. This study shows the clinical value of measuring cerebral perfusion using NIRS, an easy to use and readily applicable tool, in the assessment of syncope. Abstract Figure. Cerebral oxygenation upon standing

Do Large Vessels Affect Hemodynamic Monitoring by Near Infrared Spectroscopy?

Near Infrared Spectroscopy (NIRS) is a widely used technique to assess local tissue oxygenation and blood volume. However, several confounding factors complicate its interpretation. Among these is the potential influence exerted on NIRS variables by large vessels possibly located within the sample volume. This influence is generally neglected, according to the consideration that infrared light entering a large vessel is completely absorbed and thus not backscattered to the receiving optode. On the other hand, vessel size changes vary the amount of light absorbed and thus should profoundly affect NIRS variables. Aim of this study is to ascertain whether vessel size changes, as produced by venous occlusion, can affect NIRS blood volume indices. NIRS monitoring was performed over the basilic vein (BV) in 12 subjects (9 M – 3 F; age 31±8 yr) simultaneously to ultrasound assessment of BV size at the same location, while a second NIRS probe was positioned on the biceps muscle (BM), over a virtually vessel-free area. The arm was elevated (~60°) to induce vein collapse and subjected to venous occlusion, according to two pressure profiles: slow (from 0 to 60 mmHg in 135 s; plateau, 30 s; deflation to 0 mmHg in 135 s) and fast (step inflation to 40 mmHg maintained for 30 s). The cross-sectional area of the BV was continuously recorded along with a NIRS blood volume indicator, i.e., the total hemoglobin concentration (tHb). The tHb index detected a blood volume increase 1.7 and 2.5 times larger over BV than over BM during both slow (p<0.01) and fast (p<0.01) venous occlusions, respectively. The responses to slow venous occlusion exhibited different time courses: tHbBM exhibited a rather linear rise with time, while tHbBV showed a steeper rise at the beginning of the response, resulting in a higher convexity of the curve (p=0.01), similar to the time course of BV size. Similar patterns could be observed also in response to fast occlusions (p<0.05) and also on THI tracings (p<0.05 for both slow and fast occlusions). On average, tHbBV tracings were better correlated to BV area tracings (r=0.90) than tHbBM (r=0.83, p<0.001, after Z-transform), in response to the slow occlusion. In addition, respiratory oscillations in BV size were observed in tHbBV and not in tHbBM. In conclusion, these results challenge the long standing belief that large vessels are excluded from the NIRS sample volume. Experimental evidence strongly supports the concept that size changes of large vessels may profoundly affect NIRS variables. Neglecting this possibility may potentially introduce relevant artefacts in NIRS variables in all conditions affecting venous blood pressure, such as postural changes, or the extravascular pressure, such as muscle contraction.

Nocturnal cerebral tissue oxygenation in lowlanders with chronic obstructive pulmonary disease travelling to an altitude of 2,590m: Data from a randomised trial.

Altitude exposure induces hypoxaemia in patients with chronic obstructive pulmonary disease (COPD), particularly during sleep. The present study tested the hypothesis in patients with COPD staying overnight at high altitude that nocturnal arterial hypoxaemia is associated with impaired cerebral tissue oxygenation (CTO). A total of 35 patients with moderate-to-severe COPD, living at <800m (mean [SD] age 62.4[12.3]years, forced expiratory volume in 1s [FEV1 ] 61[16]% predicted, awake pulse oximetry ≥92%) underwent continuous overnight monitoring of pulse oximetry (oxygen saturation [SpO2 ]) and near-infrared spectroscopy of prefrontal CTO, respectively, at 490m and 2,590m. Regression analysis was used to evaluate whether nocturnal arterial desaturation (COPDDesat , SpO2 <90% for >30% of night-time) at 490m predicted CTO at 2,590m when controlling for baseline variables. At 2,590m, mean nocturnal SpO2 and CTO were decreased versus 490m, mean change -8.8% (95% confidence interval [CI] -10.0 to -7.6) and -3.6% (95% CI -5.7 to -1.6), difference in change ΔCTO-ΔSpO2 5.2% (95% CI 3.0 to 7.3; p<.001). Moreover, frequent cyclic desaturations (≥4% dips/hr) occurred in SpO2 and CTO, mean change from 490m 35.3/hr (95% CI 24.9 to 45.7) and 3.4/hr (95% CI 1.4 to 5.3), difference in change ΔCTO-ΔSpO2 -32.8/hr (95% CI -43.8 to -21.8; p<.001). Regression analysis confirmed an association of COPDDesat with lower CTO at 2,590m (coefficient -7.6%, 95% CI -13.2 to -2.0; p=.007) when controlling for several confounders. We conclude that lowlanders with COPD staying overnight at 2,590m experience altitude-induced hypoxaemia and periodic breathing in association with sustained and intermittent cerebral deoxygenation. Although less pronounced than the arterial deoxygenation, the altitude-induced cerebral tissue deoxygenation may represent a risk of brain dysfunction, especially in patients with COPD with nocturnal hypoxaemia at low altitude.

The clinical effects of cerebral near-infrared spectroscopy monitoring (NIRS) versus no monitoring: a protocol for a systematic review with meta-analysis and trial sequential analysis

BackgroundMultiple clinical conditions are associated with cerebral hypoxia/ischaemia and thereby an increased risk of hypoxic-ischaemic brain injury. Cerebral near-infrared spectroscopy monitoring (NIRS) is a tool to monitor brain oxygenation and perfusion, and the clinical uptake of NIRS has expanded over recent years. Specifically, NIRS is used in the neonatal, paediatric, and adult perioperative and intensive care settings. However, the available literature suggests that clinical benefits and harms of cerebral NIRS monitoring are uncertain. As rates of clinically significant hypoxic-ischaemic brain injuries are typically low, it is difficult for randomised clinical trials to capture a sufficiently large number of events to evaluate the clinical effect of cerebral NIRS monitoring, when focusing on specific clinical settings. The aim of this systematic review will be to evaluate the benefits and harms of clinical care with access to cerebral NIRS monitoring versus clinical care without cerebral NIRS monitoring in children and adults across all clinical settings.MethodsWe will conduct a systematic review with meta-analysis and trial sequential analysis. We will only include randomised clinical trials. The primary outcomes are all-cause mortality, moderate or severe persistent cognitive or neurological deficit, and proportion of participants with one or more serious adverse events. We will search CENTRAL, EMBASE, MEDLINE, and the Science Citation Index Expanded from their inception and onwards. Two reviewers will independently screen all citations, full-text articles, and extract data. The risk of bias will be appraised using the Cochrane risk of bias tool version 2.0. If feasible, we will conduct both random-effects meta-analysis and fixed-effect meta-analysis of outcome data. Additional analysis will be conducted to explore the potential sources of heterogeneity (e.g. risk of bias, clinical setting).DiscussionAs we include trials across multiple clinical settings, there is an increased probability of reaching a sufficient information size. However, heterogeneity between the included trials may impair our ability to interpret results to specific clinical settings. In this situation, we may have to depend on subgroup analyses with inherent increased risks of type I and II errors.Systematic review registrationPROSPERO CRD42020202986. This systematic review protocol has been submitted for registration in the International Prospective Register of Systematic Reviews (PROSPERO) (http://www.crd.york.ac.uk/prospero) on the 12th of October 2020 and published on the 12th of November 2020 (registration ID CRD42020202986).

Evaluation of the relationship between NIRS (near-infrared spectroscopy) and optic nerve sheath diameter measurement in children with increased intracranial pressure: a pilot study

BackgroundThe increased intracranial pressure (ICP) syndrome may emerge depending on many different neurological factors and the early diagnosis and treatment are important for the prevention of neurologic damage and related mortality. In recent years, the follow-up of increased ICP with non-invasive methods has been rising. In this study, our objective was to determine the significance and any possible correlation between Optic Nerve Sheath Diameter (ONSD) and Near Infrared Spectroscopy (NIRS) in children with increased ICP.MethodsPatients who were hospitalized in our pediatric ICU at Çukurova University Medical Faculty between June 2018 and June 2019 due to the suspicion of increased ICP were included in this study. The demographic characteristics of patients, diagnosis at admission, results of the cranial CT and MRI examinations, and results of the simultaneous ONSD and NIRS measurements were recorded.ResultsA total of 36 patients were included in our study. With respect to the diagnosis, non-traumatic causes were at the forefront in 30 patients (83.3%), and the most common causes were meningoencephalitis (n = 9; 25%) and non-traumatic bleeding (n = 7; 19.4%). Six of the patients were under the age of one year (16.7%), and the mean values of ONSD and NIRS were 4.8 ± 0.7 mm and 71.1 ± 12.4% respectively in this group. Fourteen patients were in the one to ten year age group and the mean values of ONSD and NIRS were 6.1 ± 0.6 mm and 72.7 ± 9.3% respectively. Sixteen patients were over ten years of age (44.4%), and the mean values of ONSD and NIRS were 5.6 ± 0.7 mm and 74.2 ± 16% respectively. There was no correlation between the ONSD and NIRS values (r:0.307; p = 0.068).ConclusionOur study showed that ONSD measurements were helpful in children with increased ICP and reflected the increase in ICP. However, our study also demonstrated that ONSD was not in correlation with the NIRS monitoring. We believe that there is a need for further studies focused on the use of ONSD and NIRS in the monitoring of increased ICP.

Monitoring Breast Reconstruction Flaps Using Near-Infrared Spectroscopy Tissue Oximetry.

Free flap reconstruction is a common procedure with success rates greater than 99%. However, vascular complications may occur, resulting in flap failure. For this reason, early detection of vascular compromise is crucial for flap salvage. Vascular complications may be detected early by monitoring tissue oximetry parameter changes using near-infrared spectroscopy (NIRS). This method of noninvasive monitoring can evaluate changes in flap oxygenation levels caused by arterial and venous thrombosis before surgical reexploration. The goal of this study was to assess the validity of using NIRS oximetry for monitoring free flaps. We conducted a prospective cohort observational study of 10 patients undergoing breast reconstruction. We used the INVOS 7100 cerebral oximetry monitoring system (Medtronic, Dublin, Ireland) to provide 24-hr continuous postoperative monitoring of flap perfusion and compared the data with clinical assessment findings. The median patient age was 57 years (range = 41-61 years). Patients underwent immediate breast reconstruction with deep inferior epigastric perforator (DIEP) flap surgery (n = 4), delayed reconstruction with DIEP flap surgery (n = 4), transverse upper gracilis flap surgery (n = 1), and latissimus dorsi flap with lipofilling (n = 1). We successfully monitored all 10 flaps for 24 hr postoperatively. The overall flap survival rate was 100%. Findings of clinical examination, Doppler studies, and surgical outcome were consistent with NIRS monitoring. In conclusion, NIRS tissue oximetry could potentially provide a noninvasive method for effective postoperative monitoring of free flaps.

Near-infrared spectroscopy (NIRS) measured tissue oxygenation in neonates with gastroschisis: a pilot study

Background Management of gastroschisis involves either primary or staged closure. Bowel ischemia and abdominal compartment syndrome (ACS) are possible complications that can be related to a method of treatment. NIRS monitoring has never been applied in this group of patients and may allow for earlier detection of complications. Objective To assess near-infrared spectroscopy (NIRS) monitoring in neonates with gastroschisis for detecting changes in tissue oxygenation (rSO2) related to bowel reductions or height of bowel in the silo and for detecting tissue ischemia. Methods Patients with gastroschisis and controls underwent continuous multi-channel assessment of oxygenation of the brain (CrSO2), kidney (RrSO2) and bowel (GrSO2) in a prospective pilot study. Results Fifteen neonates were treated with primary closure (n = 3) or staged closure (n = 12); two had confirmed bowel ischemia, none developed ACS. There was no significant correlation between height of the bowel and GrSO2 at apex (p = .72) or base (p = .54) within the silo. During staged reductions there was a clinically non-significant change in RrSO2 (Δ-2.5%, p = .04), but no significant changes in CrSO2 (p = .11), and GrSO2 of apex (p = .97) and base (p = .31). Patients with confirmed ischemia had GrSO2 that were lower than controls. Conclusions Measuring GrSO2 through a silo is feasible. Staged reduction seems safe based on NIRS measurements, with minimal effect of hydrostatic pressure on bowel oxygenation. NIRS was able to detect subtle changes in intra-abdominal renal perfusion during reduction and could differentiate healthy and ischemic bowel.

Neonatal NIRS monitoring: recommendations for data capture and review of analytics.

Brain injury is one of the most consequential problems facing neonates, with many preterm and term infants at risk for cerebral hypoxia and ischemia. To develop effective neuroprotective strategies, the mechanistic basis for brain injury must be understood. The fragile state of neonates presents unique research challenges; invasive measures of cerebral blood flow and oxygenation assessment exceed tolerable risk profiles. Near-infrared spectroscopy (NIRS) can safely and non-invasively estimate cerebral oxygenation, a correlate of cerebral perfusion, offering insight into brain injury-related mechanisms. Unfortunately, lack of standardization in device application, recording methods, and error/artifact correction have left the field fractured. In this article, we provide a framework for neonatal NIRS research. Our goal is to provide a rational basis for NIRS data capture and processing that may result in better comparability between studies. It is also intended to serve as a primer for new NIRS researchers and assist with investigation initiation.

Clinical Applications of Near-infrared Spectroscopy Monitoring in Cardiovascular Surgery.

Near-infrared spectroscopy monitoring provides a practical method to follow trends in superficial cerebral cortex oxygenation during and after cardiovascular surgery. Determination of the limits of cerebral pressure–flow autoregulation is now possible using processed oximetry signals in relation to arterial pressure.

Transcutaneous near-infrared spectroscopy (NIRS) for monitoring kidney and liver allograft perfusion.

The use of transcutaneous near-infrared spectroscopy (NIRS) for monitoring the perfusion of kidney and liver allografts has been proposed in the last years. This device might detect an early decrease in allograft oxygenation allowing prompt detection of vascular complications. A systematic review of the literature about the use of transcutaneous NIRS in monitoring allograft perfusion was performed according to the PRISMA guidelines. The authors screened 1313 papers. The search yielded five pertinent articles. Three of them reported the experience of NIRS in kidney transplantation and the other two dealt with its use in liver transplantation, for a total of 55 paediatric patients and 121 adults. In the studies concerning kidney transplantation, NIRS measurements were significantly related to serum creatinine, estimated glomerular filtration rate (eGFR), urinary neutrophil gelatinase-associated lipocalin (u-NGAL), serum lactate, resistive index assessed by Doppler-ultrasonography and systolic blood pressure. The two studies dealing with liver transplantation found a significant decrease in liver regional oxygenation, assessed by NIRS, before the occurrence of vascular complications. Preliminary studies have related NIRS monitoring to kidney and liver allograft perfusion, both in adults and children. Further investigation is needed to establish the normal range of NIRS values and the factors influencing NIRS monitoring.

Association of Cerebral Oxymetry with Short-Term Outcome in Critically ill Children Undergoing Extracorporeal Membrane Oxygenation.

Acute brain injury (ABI) is a frequent complication of pediatric extracorporeal membrane oxygenation (ECMO) that could be detected by continuous neuromonitoring. Cerebral near-infrared spectroscopy (NIRS) allows monitoring of cerebral oxygenation. To assess whether an impaired cerebral oxygenation was associated with short-term outcome during pediatric ECMO. We conducted a single-center retrospective study in a pediatric intensive care unit. Children under 18years old were included if receiving veno-venous or veno-arterial ECMO with concurrent NIRS monitoring. Cerebral saturation impairment was defined as rScO2 under 50% or 20% from the baseline for desaturation, and above 80%. Cerebral imaging (magnetic resonance imaging or CT scan) was performed in case of neurological concern. A radiologist blinded for patient history identified ABI as any hemorragic or ischemic lesion, then classified as major or minor. Primary endpoint was the outcome at hospital discharge. Poor outcome was defined as death or survival with a pediatric cerebral performance category scale (PCPC) score ≥ 3 and/or a major ABI. Good outcome was defined as survival with a PCPC score ≤ 2 and/or a minor or no ABI. Secondary endpoint was mortality before PICU discharge. Sixty-three patients met inclusion criteria; 48 (76%) had veno-arterial ECMO. Mortality rate was 51%. Forty-eight of sixty-three patients (76%) evolved with a poor outcome, including 20 major ABI. Mean rScO2 in the right/left hemisphere was 73 ± 9%/75 ± 9%. Cerebral desaturation and decline of rScO2 below 20% from the baseline, regardless of side, were each associated with poor outcome (multivariable-adjusted odds ratio (OR), 4 [95%CI 1.2; 15.1], p = 0.03, and 3.9 [95%CI 1.1; 14.9], p = 0.04, respectively), as well as a mean right rScO2 < 70% during the ECMO course (adjusted OR, 5.6 [95%CI 1.3; 34], p = 0.04). Left rSCO2 ≥ 80% was inversely correlated with hospital mortality (adjusted OR of 0.14 [95%CI0.02; 0.8], p = 0.04). Cerebral desaturation attested by NIRS was associated with a poor short-term outcome in children of all ages undergoing ECMO, and rScO2 > 80% seemed to be protective. NIRS monitoring might be included within multimodal neuromonitoring to assess the risk of the brain injury related to pediatric ECMO.

Comparing near-infrared spectroscopy monitoring and stump pressure measurement to estimate the need for shunting during carotid artery endarterectomy

Comparing near-infrared spectroscopy monitoring and stump pressure measurement to estimate the need for shunting during carotid artery endarterectomy

The Effects of Endotracheal Suctioning on Hemodynamic Parameters and Tissue Oxygenation in Pediatric Intensive Care Unit.

Airway secretions may increase in intubated patients due to the impaired mucociliary clearance, impaired cough reflex, abnormal glottic function, insufficient moisturizing, and respiratory tract infections. As with any intervention, patients should be cautiously monitored for possible complications during the endotracheal suctioning. Procedure-related changes in the cerebral and somatic tissue oxygenation, hemodynamics, and oxygen saturation can be observed in these patients. It is important to ensure maintenance of tissue oxygenation during these and other interventions performed in critically ill children. The aim of this study was to investigate the effects of the endotracheal suctioning on tissue oxygenation in patients undergoing mechanical ventilation in the pediatric intensive care unit. Cerebral and somatic near-infrared spectroscopy (NIRS) monitoring were performed noninvasively using standardized NIRS equipment as a means of monitoring regional tissue oxygenation. Vital signs, level of sedation, pain scores, and somatic and cerebral tissue oxygenation values of mechanically ventilated patients were recorded prospectively 5 minutes before, during, and after endotracheal suctioning. Cerebral NIRS measurements did not exhibit any statistically significant changes during endotracheal suctioning. Somatic NIRS levels changed significantly before, during, and after endotracheal suctioning and remained low throughout the procedure. Endotracheal suctioning is an invasive intervention that facilitates clearance of tracheal secretions and maintenance of the oxygenation and ventilation. The maintenance of the tissue oxygenation should be documented during these and other interventions performed on critically ill children. Somatic NIRS is a useful tool for monitoring tissue oxygenation during such procedures.

Non-invasive continuous renal tissue oxygenation monitoring to identify preterm neonates at risk for acute kidney injury.

Near-infrared spectroscopy (NIRS) is an emerging tool to identify signs of inadequate tissue oxygenation in preterm neonates with acute kidney injury (AKI). Previous studies have shown a correlation between low renal tissue oxygenation (RrSO2) in the first 24hours of age and the later development of AKI. In this prospective clinical trial, NIRS monitoring was used to identify changes in RrSO2 in comparison to traditional AKI markers, serum creatinine (SCr), and urine output (UOP). We enrolled 35 preterm neonates born less than 32weeks' gestation and applied neonatal NIRS sensors at less than 48hours of age. Neonates underwent 7days of continuous monitoring. Renal and demographic information were collected for the first 7days of age. AKI was determined by the modified neonatal Kidney Disease: Improving Global Outcomes (KDIGO) definition including UOP. Three patients experienced AKI, all based on both SCr and UOP criteria. Each neonate with AKI had decreases in RrSO2 over 48hours prior to changes in SCr and UOP. Patients with AKI had lower median RrSO2 values compared to patients without AKI over the first week of age, (32.4% vs. 60%, p < 0.001). RrSO2 monitoring identified preterm neonates at risk for AKI. NIRS detected a decline in RrSO2 prior to changes in SCr and UOP and was significantly lower in patients with AKI compared to those without AKI. Further studies are needed to evaluate the ability of RrSO2 monitoring to detect signs of kidney stress prior to the diagnosis of AKI. Graphical abstract.

Monitoring distal limb perfusion using near-infrared spectroscopy in patients on intra-aortic balloon pump

Background: The application of near-infrared spectroscopy (NIRS) in patients undergoing cardiopulmonary bypass for the purpose of monitoring cerebral perfusion is well known. There have been only a few reports of its use in adult patients undergoing peripheral veno-arterial extracorporeal membrane oxygenation to monitor lower limb perfusion. Aim and Objective: Our study aimed to understand the usefulness of NIRS monitoring for the early detection of reduced distal limb perfusion in patients who were placed on intra-aortic balloon pump (IABP) through femoral artery. Materials and Methods: We prospectively studied the use of NIRS monitoring for the early detection of reduced distal limb perfusion in 36 adult patients, who were supported with IABP between 2018 and 2019 (NIRS group). The decision to reinsert the IABP in the contralateral lower limb was made based on the NIRS system’s regional oxygen saturation (rSO2) values. To compare outcomes, the medical records of 45 adult patients who had previously received IABP without NIRS monitoring (control group) between 2017 and 2018 were reviewed retrospectively. Institutional Ethical Committee Approval was taken ref. no. IEC/39/18 dated January 22, 2018. Results: There was no significant difference between the frequency of reinsertion of IABP in the contralateral lower limb in both groups (P = 0.414). The mean time to reinsertion of IABP in the contralateral lower limb is shorter in the NIRS group (20.6 ± 21.4 vs. 40.0 ± 61.0 h). In the NIRS group, no patients underwent fasciotomy, whereas 13.5% did in the control group (P = 0.030). Conclusion: We believe that NIRS monitoring is an effective and accurate approach for detecting limb ischemia in IABP patients. Its use could lead to the early correction of perfusion deficits, as well as the avoidance of compartment syndrome and limb problems.

Utility of Ultrasonographic Assessment of Distal Femoral Arterial Flow during Minimally Invasive Valve Surgery.

Purpose: To evaluate the utility of ultrasonographic assessment of blood flow to the lower limb below the cannulation site in minimally invasive cardiac surgery (MICS).Methods: Twenty-two patients who underwent ultrasonographic assessment in MICS were reviewed retrospectively. In all patients, the right femoral artery was used for arterial cannulation. Ultrasonographic assessment was performed using a 15-MHz ultrasonography small probe, and regional oxygen saturation was monitored by near-infrared spectroscopy (NIRS).Results: The mean flow velocity at the distal side of the cannulation site was 46.2 ± 25.4 cm/s. In six patients, a >40% decreased from baseline regional oxygen saturation was observed. In five of the six patients, the flow velocity was very slow, and spontaneous echo contrast was also observed in three cases. Their regional oxygen saturation was improved rapidly after distal leg perfusion. In the remaining case, the flow velocity was not decreased. In another one case, the stenosis at the cannulation site was detected after decannulation and repaired immediately. No limb ischemic complications were observed in this series.Conclusion: Ultrasonographic assessment combined with the NIRS monitoring is useful to prevent lower limb ischemic complications after femoral arterial cannulation in MICS.

Effects of Sevoflurane and Propofol Anesthesia on Cerebral Oxygenation in Patients Undergoing Carotid Endarterectomy.

To compare the effects of sevoflurane and propofol anesthesia on perioperative cerebral oxygenation in patients undergoing carotid endarterectomy (CEA) under general anesthesia by using near-infrared spectroscopy (NIRS) monitoring. Institutional approval was obtained, and the perioperative data of 33 patients undergoing CEA were retrospectively evaluated. The study groups were organized according to the anesthesia drugs used for maintenance: sevoflurane (n=17) and propofol (n=16). The regional cerebral oxygen saturation (rScO < sub > 2 < /sub > ) of the ipsilateral and contralateral hemispheres was monitored continuously using a NIRS instrument and analyzed at specific time points starting from induction to the 12th hour postoperation. The data were analyzed using the appropriate tests, and a p value of < 0.05 was considered significant. Compared with those of groups with non-clamped hemispheres, the rScO < sub > 2 < /sub > values of the sevoflurane and propofol groups decreased significantly during clamping (p < 0.05) and increased to above-preoperative values after declamping (p < 0.05). When the sevoflurane and propofol groups were compared, a significant decrease in rScO < sub > 2 < /sub > was noted during extubation in the sevoflurane group (p < 0.05). In the propofol group, female patients had significantly lower rScO < sub > 2 < /sub > values compared with male patients during clamping of the carotid artery (p < 0.05). None of the observed decreases was greater than 20%, which is considered an indication for shunting. Our NIRS monitoring results indicate that sevoflurane or propofol anesthesia does not generally cause significant differences in cerebral oxygenation during and after cross-clamping in patients undergoing CEA. The finding of sex-related differences in cerebral oxygenation in patients receiving propofol and decreased oxygenation during extubation in patients receiving sevoflurane warrants further studies.

An Elusive Prize: Transcutaneous Near InfraRed Spectroscopy (NIRS) Monitoring of the Liver.

Introduction: We postulate a relationship between a transcutaneous hepatic NIRS measurement and a directly obtained hepatic vein saturation. If true, hepatic NIRS monitoring (in conjunction with the current dual-site cerebral-renal NIRS paradigm) might increase the sensitivity for detecting shock since regional oxygen delivery changes in the splanchnic circulation before the kidney or brain. We explored a reliable technique for hepatic NIRS monitoring as a prelude to rigorously testing this hypothesis. This proof-of-concept study aimed to validate hepatic NIRS monitoring by comparing hepatic NIRS measurements to direct hepatic vein samples obtained during cardiac catheterization.Method: IRB-approved prospective pilot study of hepatic NIRS monitoring involving 10 patients without liver disease who were already undergoing elective cardiac catheterization. We placed a NIRS monitor on the skin overlying liver during catheterization. Direct measurement of hepatic vein oxygen saturation during the case compared with simultaneous hepatic NIRS measurement.Results: There was no correlation between the Hepatic NIRS values and the directly measured hepatic vein saturation (R = −0.035; P = 0.9238). However, the Hepatic NIRS values correlated with the cardiac output (R = 0.808; P = 0.0047), the systolic arterial blood pressure (R = 0.739; P = 0.0146), and the diastolic arterial blood pressure (R = 0.7548; P = 0.0116).Conclusions: Using the technique described, hepatic NIRS does not correlate well with the hepatic vein saturation. Further optimization of the technique might provide a better measurement. Hepatic NIRS does correlate with cardiac output and thus may still provide a valuable additional piece of hemodynamic information when combined with other non-invasive monitoring.

Significance of the ability to differentiate emotional prosodies for the early diagnosis and prognostic prediction of mild hypoxic-ischemic encephalopathy in neonates.

Perinatal brain injury affects around 300,000 neonates in China each year, early diagnosis and active intervention are also crucial for timely treatment and better prognoses. As hearing is the earliest as well as the most sensitive sense to develop in neonates, we propose that the ability to differentiate among different emotional prosodies may differ between neonates with and without brain injuries. We enrolled full-term neonates admitted to the neonatology department of Peking University First Hospital from January 2016 to December 2016, conducted functional near-infrared spectroscopy (fNIRS) monitoring within 24hr of admission, and analyzed changes in oxyhemoglobin (ΔHbO2 ) and deoxyhemoglobin (ΔHb) to study the ability of neonates to differentiate among emotional prosodies. The neonates were followed up to 36months for neurological outcome evaluation. We found that neonates showed the early ability to differentiate among emotional prosodies, responding most sensitively to positive emotions, and this ability may have been impaired following brain injury.

Association between Regional Tissue Oxygenation and Body Temperature in Term and Preterm Infants Born by Caesarean Section.

Body temperature (BT) management remains a challenge in neonatal intensive care, especially during resuscitation after birth. Our aim is to analyze whether there is an association between the BT and cerebral and peripheral tissue oxygen saturation (crSO2/cTOI and prSO2), arterial oxygen saturation (SpO2), and heart rate (HR). The secondary outcome parameters of five prospective observational studies are analyzed. We include preterm and term neonates born by Caesarean section who received continuous pulse oximetry and near-infrared spectroscopy monitoring during the first 15 min, and a rectal BT measurement once in minute 15 after birth. Four-hundred seventeen term and 169 preterm neonates are included. The BT did not correlate with crSO2/cTOI and SpO2. The BT correlated with the HR in all neonates (ρ = 0.210, p < 0.001) and with prSO2 only in preterm neonates (ρ = −0.285, p = 0.020). The BT was lower in preterm compared to term infants (36.7 [36.4–37.0] vs. 36.8 [36.6–37.0], p = 0.001) and prevalence of hypothermia was higher in preterm neonates (29.5% vs. 12.0%, p < 0.001). To conclude, the BT did not correlate with SpO2 and crSO2/cTOI, however, there was a weak positive correlation between the BT and the HR in the whole cohort and a weak correlation between the BT and prSO2 only in preterm infants. Preterm neonates had a statistically lower BT and suffered significantly more often from hypothermia during postnatal transition.