Effects of phenylephrine on systemic and cerebral circulations in humans: a systematic review with mechanistic explanations.

We conducted a systematic review of the literature reporting phenylephrine-induced changes in blood pressure, cardiac output, cerebral blood flow and cerebral tissue oxygen saturation as measured by near-infrared spectroscopy in humans. We used the proportion change of the group mean values reported by the original studies in our analysis. Phenylephrine elevates blood pressure whilst concurrently inducing a reduction in cardiac output. Furthermore, despite increasing cerebral blood flow, it decreases cerebral tissue oxygen saturation. The extent of phenylephrine's influence on cardiac output (r = -0.54 and p = 0.09 in awake humans; r = -0.55 and p = 0.007 in anaesthetised humans), cerebral blood flow (r = 0.65 and p = 0.002 in awake humans; r = 0.80 and p = 0.003 in anaesthetised humans) and cerebral tissue oxygen saturation (r = -0.72 and p = 0.03 in awake humans; r = -0.24 and p = 0.48 in anaesthetised humans) appears closely linked to the magnitude of phenylephrine-induced blood pressure changes. When comparing the effects of phenylephrine in awake and anaesthetised humans, we found no evidence of a significant difference in cardiac output, cerebral blood flow or cerebral tissue oxygen saturation. There was also no evidence of a significant difference in effect on systemic and cerebral circulations whether phenylephrine was given by bolus or infusion. We explore the underlying mechanisms driving the phenylephrine-induced cardiac output reduction, cerebral blood flow increase and cerebral tissue oxygen saturation decrease. Individualised treatment approaches, close monitoring and consideration of potential risks and benefits remain vital to the safe and effective use of phenylephrine in acute care.

Evaluation of cerebral autoregulation of oxygen by NIRS method during postnatal transition period in term and late preterm newborns without resuscitation requirement.

BACKGROUND: Pulse oximetry is commonly used to monitor arterial oxygen saturation and heart rate during the transition period and reference intervals have been determined. However, the effect of the change in arterial oxygen saturation on tissue oxygenation does not seem to be the same. So, a non-invasive method for monitoring cerebral or regional tissue oxygenation will be potentially useful for vulnerable infants. This study aims to evaluate the effectiveness of cerebral autoregulation in the first 10 min after delivery in term and late preterm newborns without resuscitation requirement. METHODS: Cerebral tissue oxygen saturation was measured in the first 10 min after birth with near-infrared spectroscopy (NIRS) from the left forehead. Peripheral oxygen saturation was measured with pulse oximetry from the right hand and cerebral fractional tissue oxygen extraction was calculated. RESULTS: Nineteen late preterms and 20 term infants were included in the study. There was no statistically significant difference between median cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction values of late preterm and term infants (p < 0.001). There was a strong inverse relationship between cerebral tissue oxygen saturation and cerebral fractional tissue oxygen extraction (p < 0.001). CONCLUSIONS: In late preterm infants similar to term infants, arterial oxygen saturation and cerebral tissue oxygen saturation increased with time, but inverse reduction of cerebral fractional tissue oxygen extraction showed the presence of an active autoregulation in the brain. This can be interpreted as the ability of the brain to protect itself from hypoxia by regulating oxygen uptake during normal fetal-neonatal transition process. A larger scale multi-center randomized control trial is now needed to further inform practice.

Normalization of low frontal regional cerebral oxygenation after evacuation of chronic subdural hematoma in a patient with bilateral internal carotid artery stenosis.

Near infrared spectroscopy (NIRS) technology is frequently used to measure regional cerebral tissue oxygen saturation (rSO2). The measurement of rSO2 has diverse range of clinical application for its easy bed-side applicability, continuous monitoring, interpretation and valuable information on cerebral oxygenation. However, it also has few technical limitations; absorption by skull tissues, presence of hematomas, and other pigments such as melanin, bilirubin can affect the rSO2 measurements and thus interfere with the accuracy of monitoring. We report a case wherein low values of frontal rSO2 normalized after evacuation of bilateral fronto-temporo-parietal (FTP) chronic subdural hematoma (CSDH) in a patient with bilateral internal carotid artery (ICA) stenosis.

Frontal Cerebral Oxygenation in Humans at Rest: A Mirror Symmetry in the Correlation with Cardiorespiratory Activity.

BACKGROUND: Although several studies published reference values for frontal cerebral tissue oxygen saturation (StO2) measured with near-infrared spectroscopy (NIRS) based cerebral oximetry, a detailed investigation, whether and which factors from systemic physiology are related to the individual StO2 values, is missing. AIM: We investigated how the state of the cardiorespiratory system is linked to StO2 values at rest. SUBJECTS AND METHODS: Absolute StO2 values (median over a 5 min resting-phase while sitting) were obtained from 126 healthy subjects (age: 24.0 ± 0.2 years, 45 males, 81 females) over the left and right prefrontal cortex (PFC) by employing frequency-domain NIRS as part of a systemic physiology augmented functional near-infrared spectroscopy (SPA-fNIRS) study. In addition, heart rate (HR) and respiration rate (RR) were measured, and the pulse respiration quotient (PRQ) was determined (PRQ = HR/RR). General additive models (GAM) were used to analyse the data. RESULTS: The GAM analysis revealed a specific relationship between the overall PFC StO2 values (mean over right and left PFC) and the variables HR and RR: HR was positively correlated with mean StO2, while RR showed no correlation. In the mirror case, RR was negatively linearly correlated with the frontal cerebral oxygenation asymmetry (FCOA), which was not correlated with HR. The right PFC StO2 was not linked to the RR, whereas the left PFC StO2 was. Positive correlations of the PRQ with the mean PFC StO2 as well as the FCOA were also found. GAM modelling revealed that the individual FCOA values are explained to a large extent (deviance explained: 88.8%) by the individual mean PFC StO2 and PRQ. We conclude that (i) the state of the cardiorespiratory system is significantly correlated with StO2 values and (ii) there is a mirror symmetry with regard to the impact of cardiorespiratory parameters on the mean PFC StO2 and FCOA.

The effect of selective cerebral perfusion on cerebral versus somatic tissue oxygenation during aortic coarctation repair in neonates and infants.

BACKGROUND: Suboptimal tissue perfusion and oxygenation may be the root cause of certain perioperative complications in neonates and infants having complicated aortic coarctation repair. Practical, effective, and real-time monitoring of organ perfusion and/or tissue oxygenation may provide early warning of end-organ mal-perfusion. METHODS: Neonates/infants who were scheduled for aortic coarctation repair with cardiopulmonary bypass (CPB) and selective cerebral perfusion (SCP) from January 2015 to February 2017 in Children's Hospital of Nanjing Medical University participated in this prospective observational study. Cerebral and somatic tissue oxygen saturation (SctO2 and SstO2) were monitored on the forehead and at the thoracolumbar paraspinal region, respectively. SctO2 and SstO2 were recorded at different time points (baseline, skin incision, CPB start, SCP start, SCP end, aortic opening, CPB end, and surgery end). SctO2 and SstO2 were correlated with mean arterial pressure (MAP) and partial pressure of arterial blood carbon dioxide (PaCO2). RESULTS: Data of 21 patients were analyzed (age=75±67 days, body weight=4.4±1.0 kg). SstO2 was significantly lower than SctO2 before aortic opening and significantly higher than SctO2 after aortic opening. SstO2 correlated with leg MAP when the measurements during SCP were (r=0.67, p<0.0001) and were not included (r=0.46, p<0.0001); in contrast, SctO2 correlated with arm MAP only when the measurements during SCP were excluded (r=0.14, p=0.08 vs. r=0.66, p<0.0001). SCP also confounded SctO2/SstO2's correlation with PaCO2; when the measurements during SCP were excluded, SctO2 positively correlated with PaCO2 (r=0.65, p<0.0001), while SstO2 negatively correlated with PaCO2 (r=-0.53, p<0.0001). CONCLUSIONS: SctO2 and SstO2 have distinct patterns of changes before and after aortic opening during neonate/infant aortic coarctation repair. SctO2/SstO2's correlations with MAP and PaCO2 are confounded by SCP. The outcome impact of combined SctO2/SstO2 monitoring remains to be studied.

Do cerebral and somatic tissue oxygen saturation measurements correlate with each other during surgery?

Intraoperative maintenance of optimal tissue oxygenation is critical; however, it is uncertain whether measurements of different tissue beds correlate with each other. Cerebral tissue oxygen saturation (SctO2) measured on the forehead and somatic tissue oxygen saturation (SstO2) measured on limbs, using a tissue near-infrared spectroscopy, were simultaneously recorded every 2 s in patients having spine surgery or robotic hysterectomy. Simple linear regression was used to determine the static correlation between SctO2 and SstO2 using the median values of each min for each patient. The dynamic correlation between SctO2 and SstO2 was assessed by Pearson's correlation coefficient (CC) for each non-overlapping 2-min epoch. In patients having spine surgery (n = 99), SctO2 and SstO2 (mean ± SD) were 69.8 ± 4.9% and 75.5 ± 8.7%, whereas in patients having robotic hysterectomy (n = 106), the corresponding values were 74.9 ± 6.8% and 83.7 ± 6.2%. The static correlation between SctO2 and SstO2 was inconsistent (r ranging from - 0.86 to 0.93 in spine surgery and from - 0.74 to 0.85 in robotic hysterectomy). The proportional durations with CC ≤ - 0.3 (negative correlation), - 0.3 < CC < 0.3 (poor correlation) and CC ≥ 0.3 (positive correlation) were 18.3 ± 9.6%, 52.6 ± 12.1% and 29.0 ± 9.6%, respectively, in patients having spine surgery and 19.6 ± 9.0%, 58.6 ± 13.1% and 21.8 ± 8.0%, respectively, in patients having robotic hysterectomy. There are a large discrepancy and inconsistent correlation between intraoperative SctO2 and SstO2 measurements, suggesting their non-interchangeability.

[The value of intraoperative cerebral oxygen saturation in predicting postoperative neurocognitive dysfunction in elderly patients with mild cognitive impairment].

Objective: To evaluate the value of intraoperative cerebral oxygen saturation in predicting postoperative neurocognitive dysfunction (PND) in elderly patients with mild cognitive impairment. Methods: A total of 210 cases of lumbar decompression, bone grafting and fusion surgery under general anesthesia were collected in the Third Central Hospital of Tianjin from June, 2019 to January, 2020, either sex, aged 65-75 year, BMI 19.5-32.5 kg/m(2), ASA physical status Ⅱ or Ⅲ, preoperative comorbidities with mild cognitive impairment. MoCA and MMSE were used to evaluate the cognitive function of patients 1 day before the operation, 7 days and 3 monthes after operation. PND group (n=38) and non-PND group (n=172) were selected according to postoperative MMSE and MoCA scale scores and the diagnostic criteria of PND. Heart rate (HR) , mean arterial pressure (MAP), pulse oxygen saturation (SpO(2)), bispectral index (BIS), cerebral tissue oxygen saturation (SctO(2), average left and right brain SctO(2) were recorded) were recorded pre-anesthetic (T(0)), ten minutes of anesthesia(T(1)), twenty minutes of anesthesia (T(2)), thirty minutes into the operation (T(3)), one hour into the operation (T(4)), end of the surgery (T(5)), and leave the PACU (T(6)). SctO(2) at time point T(0) was the base value of SctO(2), and the maximum percentage drop in SctO(2) from the base value was calculated (SctO(2max)%). Results: The incidence of PND was 18% (38/210) in 210 elderly patients undergoing surgery. The age of PND group and non-PND group was (71.0±2.1) and (67.8±2.0) years old, and the PACU time was (57±5) and (46±8) min, respectively. Compared with the non-PND group, the age of the PND group was higher (t=2.600, P<0.05) and the PACU time was longer (t=3.039, P<0.05). At the time points T(3), T(4), T(5) and T(6), SctO(2) in the PND group was (62±10) %, (60±11) %, (64±12) % and (66±10)%, respectively, lower than that in the non-PND group (67±60) %, (68±6) %, (69±5) % and (70±7)%, respectively, and the difference was statistically significant (t=3.369, 4.906, 3.787, 2.516, all P<0.05).The MoCA and MMSE scores of the PND group were (22.9±1.2) and (24.1±1.2) points, respectively, 1 day before surgery; and the MoCA and MMSE scores of the PND group were reduced to (20.8±1.2) and (21.3±0.7) points, respectively, 7 days after surgery, with statistically significant differences (t=3.523, 5.675, all P<0.05). MoCA and MMSE scores 7 days after surgery in the non-PND group were (22.4±1.3) and (23.1±1.6) points, respectively. Compared with the non-PND group, MoCA and MMSE scores 7 days after surgery in the PND group were reduced (t=2.630, 3.108, all P<0.05). The critical value of intraoperative SctO(2max)% was 13.74%, the area under the curve of PND was predicted to be 0.907 (95%CI: 0.819-0.995), sensitivity and specificity were 88.9% and 88.5%, respectively. Conclusion: SctO(2max)%>13.74% can be used as an indicator to predict PND occurrence in elderly patients with mild cognitive impairment during lumbar surgery.

Two-minute disconnection technique with a double-lumen tube to speed the collapse of the non-ventilated lung for one-lung ventilation in thoracoscopic surgery.

BACKGROUND: Thoracic surgery requires the effective collapse of the non-ventilated lung. In the majority of cases, we accomplished, accelerated lung collapse using a double-lumen tube (DLT). We hypothesized that using the two-minute disconnection technique with a DLT would improve lung collapse during subsequent one-lung ventilation. METHODS: Fifty patients undergoing thoracoscopic surgery with physical classification I or II according to the American Society of Anesthesiologists were randomly divided into two groups for respiratory management of one-lung ventilation (OLV). In group N, OLV was initiated after the DLT was disconnected for 2 min; the initiation time began when the surgeon made the skin incision. In group C, OLV was initiated when the surgeon commenced the skin incision and scored the quality of lung collapse (using a four-point ordinal scale). The surgeon's satisfaction or comfort with the surgical conditions was assessed using a visual analogue scale. rSO2 level, mean arterial pressure, pulse oxygen saturation, arterial blood gas analysis, intraoperative hypoxaemia, intraoperative use of CPAP during OLV, and awakening time were determined in patients at the following time points: while inhaling air (T0), after anaesthesia induction andinhaling 100% oxygen in the supine position under double lung ventilation for five mins (T1), at two mins after skin incision (T2), at ten mins after skin incision (T3), and after the lung recruitment manoeuvres and inhaling 50% oxygen for five mins (T4). RESULTS: The two-minute disconnection technique was associated with a significantly shorter time to total lung collapse compared to that of the conventional OLV ventilation method (15 mins vs 22 mins, respectively; P < 0.001), and the overall surgeon's satisfaction was higher (9 vs 7, respectively; P < 0.001). At T2, the PaCO2, left rSO2 and right rSO2 were higher in group N than in group C. There were no statistically significant differences between the incidence of intraoperative hypoxaemia and intraoperative use of CPAP during OLV (10% vs 5%, respectively; P = 1.000), duration of awakening (18 mins vs 19 mins, respectively; P = 0.616). CONCLUSIONS: A two-minute disconnection technique using a double-lumen tube was used to speed the collapse of the non-ventilated lung during one-lung ventilation for thoracoscopic surgery. The surgeon was satisfied with the surgical conditions. TRIAL REGISTRATION: Chinese Clinical Trial Registry number, ChiCTR-IPR-17010352 . Registered on Jan, 7, 2017.

Near-Infrared Spectroscopy in Adult Cardiac Surgery Patients: A Systematic Review and Meta-Analysis.

OBJECTIVES: To identify the normal baseline preoperative range of cerebral tissue oxygen saturation (SctO2) derived using near-infrared spectroscopy (NIRS) and the efficacy of perioperative interventions designed to modulate SctO2 in cardiac surgical patients. DESIGN: Systematic review and meta-analysis of relevant randomized controlled trials (RCTs) extracted from the Medline, Embase, and Cochrane Central Register of Controlled Trials databases. SETTING: Hospitals performing cardiac surgery. PARTICIPANTS: The study comprised 953 participants from 11 RCTs. INTERVENTIONS: Interventions included the following: (1) SctO2 monitoring protocol compared with no monitoring; (2) use of cardiopulmonary bypass (CPB) compared with no CPB; (3) normothermic CPB compared with hypothermic CPB; (4) glyceryl trinitrate during surgery compared with placebo; (5) midazolam during induction of anesthesia compared with propofol; (6) sevoflurane anesthesia compared with total intravenous anesthesia; (7) sevoflurane anesthesia compared with propofol-based anesthesia; and (8) norepinephrine during CPB compared with phenylephrine. MEASUREMENTS AND MAIN RESULTS: Eleven RCTs with 953 participants measured baseline preoperative SctO2 using NIRS. The pooled mean baseline SctO2 was 66.4% (95% CI 65.0-67.7), generating a reference range of 51.0% to 81.8%. Four interventions (1, 3, 4, and 6 described in the Interventions section above) increased intraoperative SctO2 across the majority of reported time points. Postoperative follow-up of SctO2 occurred in only 1 study, and postoperative cognitive assessment correlating SctO2 with cognitive function was applied in only 4 studies using variable methodology. CONCLUSIONS: The authors have established that reference values for baseline NIRS-derived SctO2 in cardiac surgery patients are varied and have identified interventions that modulate SctO2. This information opens the door to standardized research and interventional studies in this field.

Measurement of brain tissue oxygen saturation in term infants using a new portable near-infrared spectroscopy device.

BACKGROUND: A small oximeter with the probe attached to the examiner's finger has been developed. The aim of this study was to determine the feasibility of measuring regional oxygenation of the brain tissue using this device in healthy term infants immediately after birth. METHODS: We conducted a prospective observational study. Using a new near-infrared spectroscopy (NIRS) device, we measured changes in regional cerebral tissue oxygen saturation (crSO2 ) during the first 10 min of life in 32 healthy term infants after delivery. Arterial oxygen saturation (SpO2 ) was also simultaneously measured. RESULTS: Median crSO2 increased from 43% (1 min after birth) to 49% (4 min after birth); thereafter, no significant changes were observed. Median SpO2 increased constantly from min 3 to min 7, from 77% to 92% and did not change significantly after 8 min. A stable oxygen saturation signal was measured in 59% of infants (crSO2 ) and in 0% of infants (SpO2 ) at 1 min, and in 97% (crSO2 ) and in 78% (SpO2 ) at 3 min. CONCLUSIONS: During the transition after birth, crSO2 can be more easily and quickly measured in healthy newborn infants using the novel NIRS device than SpO2 .

Cerebral tissue oxygen saturation is associated with N-terminal probrain natriuretic peptide in preterm infants on their first day of life.

AIM: This prospective observational study investigated if N-terminal probrain natriuretic peptide (NT-proBNP), a cardiac biomarker, correlated with cerebral tissue oxygen saturation (crSO2) in preterm infants on their first day of life. METHODS: Using near infrared spectroscopy (NIRS), crSO2 was measured on the right forehead of preterm infants for 24 h. We also recorded arterial oxygen saturation (SpO2 ) and calculated fractional tissue oxygen extraction (cFTOE) values. At the end of the NIRS measurement, blood was taken to analyse NT-proBNP. Mean values for the 24-h period were calculated for crSO2 , cFTOE, SpO2 and these values were correlated to NT-proBNP. An echocardiography was performed in all infants during the measurement period. RESULTS: We analysed 35 preterm neonates (33 ± 2 weeks, 1965 ± 523 g). NIRS measurements started at 3 ± 1 h and blood samples were taken at 24 ± 5 h postnatal. Echocardiography showed an open ductus arteriosus in all infants. Mean NT-proBNP was 4978 ± 3566 pg/mL, crSO2 was 76 ± 8%, and cFTOE was 0.20 ± 0.08. NT-proBNP correlated negatively with crSO2 (r = -0.75; p ≤ 0.001) and positively with cFTOE (r = 0.731; p ≤ 0.001). CONCLUSION: These results emphasise that crSO2 is influenced by cardiac function, in addition to oxygen consumption, arterial oxygen saturation and vascular resistance, and this can be measured by NT-proBNP.

Acute decrease of cerebral oxygen saturation during rapid ventricular and supraventricular rhythm: a pilot study.

BACKGROUND: Monitoring of cerebral tissue oxygen saturation (SctO2 ) reflects cerebral microcirculation. We sought to characterize the decrease in SctO2 during supraventricular tachycardia (SVT) and ventricular tachycardia (VT) in adults. METHODS: Twenty patients (mean age: 46.3 ± 18.1 years, 40% men) were included. Rapid atrial and ventricular pacing (200/min) was used as a model for VT and SVT. Near-infrared spectroscopy (NIRS) was used to measure SctO2 . RESULTS: Atrial stimulation decreased right (P = 0.014) and left (P = 0.019) hemispheric SctO2 compared to baseline. Ventricular stimulation also decreased right (P < 0.001) and left (P < 0.001) hemispheric SctO2 . A negative correlation between age and minimal value under stimulation was found for atrial (right SctO2 r = -0.641, P = 0.034; left SctO2 r = -0.694, P = 0.018) and ventricular pacing (right SctO2 r = -0.564, P = 0.01; left SctO2 r = -0.604, P = 0.005). A positive correlation was found between left ventricular ejection fraction (LVEF) and minimal value under ventricular stimulation (right SctO2 r = 0.567, P = 0.009; left SctO2 r = 0.471, P = 0.036). CONCLUSION: Cerebral perfusion decreased during simulated SVT and VT and is influenced by age and LVEF. Clinicians can consider NIRS monitoring in patients during ablation procedures and in critical care. NIRS may especially be appropriate for the elderly and for patients with impaired LVEF.

The effect of optimising cerebral tissue oxygen saturation on markers of neurological injury during coronary artery bypass graft surgery.

BACKGROUND: Surgical revascularisation of the coronary arteries is a cornerstone of cardiothoracic surgery. Advanced age and the incidence of preoperative co-morbidity in patients presenting for coronary artery bypass graft surgery increases the potential for stroke and other perioperative outcomes. It is hypothesised that by using interventions during cardiac surgery to improve cerebral oxygenation, the risk of patients enduring adverse neurological outcomes would be reduced. METHODS: Forty patients (mean age 55.3, standard deviation 9.74 and range from 39 to 72 years) undergoing on-pump coronary artery bypass graft surgery were recruited at Inkosi Albert Luthuli Central Hospital, South Africa. Patients were randomised into a control group (n=20) and interventional group (n=20). Intraoperative regional cerebral oxygen saturation (rSO2) monitoring with active display and Murkin treatment intervention protocol was administered for the interventional group. Arterial blood samples for the measurement of serum S100B were taken pre and postoperatively. An enzyme immunoassay (ELISA) was used for the quantitative and comparative measurement of human S100B concentrations for both groups. A prioritised intraoperative management protocol to maintain rSO2 values above 75% of the baseline threshold during cardiopulmonary bypass was followed. RESULTS: There was a highly significant difference in the change in S100B concentrations post surgery between the interventional (37.3picograms per millilitre) and control groups (139.3pg/ml). The control group showed a significantly higher increase in S100B concentration over time than the intervention group (p<0.001). There was a significant difference in cerebral desaturation time (p<0.001) between the groups. The mean desaturation time for the control group was 63.85min as compared to 24.7min in the interventional group. Cerebral desaturation occurred predominantly during aortic cross clamping, distal anastomosis of coronary arteries and aortic cross clamp release. Predictors of cerebral oxygen desaturation included, partial pressure of carbon dioxide (pCO2), temperature, pump flow rate (LMP), mean arterial pressure (MAP), haematocrit, heart rate (HR) and patient oxygen saturation (SpO2). CONCLUSION: Monitoring brain oxygen saturation during on-pump CABG together with an effective treatment protocol to deal with cerebral desaturation must be advocated.

The Effect of Ciprofol on Postoperative Delirium in Elderly Patients Undergoing Thoracoscopic Surgery for Lung Cancer: A Prospective, Randomized, Controlled Trial.

Purpose: This study was conducted to assess whether ciprofol vs propofol could affect the incidence of postoperative delirium (POD) in elderly patients with lung cancer after thoracoscopic surgery. Patients and Methods: In this study, a total of 84 elderly patients undergoing thoracoscopic surgery for lung cancer were recruited and randomized into two groups to receive anesthesia with either ciprofol or propofol. The primary outcome was the incidence of POD within three days after surgery. Secondary outcomes included the Confusion Assessment Method (CAM) score, intraoperative indicators related to mean arterial pressure (MAP), and cerebral tissue oxygen saturation (SctO2). Moreover, MAP- and SctO2-related indicators associated with POD were analyzed. Results: The incidence of POD was 7.1% and 16.7%, respectively, in the ciprofol group and the propofol group (risk ratio [RR], 0.37; 95% confidence interval [CI], 0.07 to 2.03; risk difference [RD], -9.6%; 95% CI, -23.3% to 4.1%; p = 0.178). Compared with those in the propofol group, patients in the ciprofol group had lower CAM scores three days after surgery (13 (12, 15) vs 15 (14, 17); 12 (11, 13) vs 14 (13, 16); 12 (11, 12) vs 13 (12, 14), p<0.05). Besides, patients in the ciprofol group exhibited higher mean and minimum MAP (88.63 ± 6.7 vs 85 ± 8.3; 69.81 ± 9.59 vs 64.9 ± 9.43, p<0.05) and SctO2 (77.26 ± 3.96 vs 75.3 ± 4.49, 71.69 ± 4.51 vs 68.77 ± 6.46, p<0.05) and percentage of time for blood pressure stabilization (0.6 ± 0.14 vs 0.45 ± 0.14, p<0.05) than those in the propofol group. Furthermore, MAP and SctO2-related indicators were validated to correlate with POD. Conclusion: Anesthesia with ciprofol did not increase the incidence of POD compared with propofol. The results demonstrated that ciprofol could improve intraoperative MAP and SctO2 levels and diminish postoperative CAM scores.

Impact of Skin Pigmentation on Cerebral Regional Saturation of Oxygen Using Near-Infrared Spectroscopy: A Systematic Review.

OBJECTIVES: Near-infrared spectroscopy (NIRS) is used in critical care settings to measure regional cerebral tissue oxygenation (rSo2). However, the accuracy of such measurements has been questioned in darker-skinned individuals due to the confounding effects of light absorption by melanin. In this systematic review, we aim to synthesize the available evidence on the effect of skin pigmentation on rSo2 readings. DATA SOURCES: We systematically searched MEDLINE, Cochrane Database of Systematic Reviews, Embase, and Google Scholar from inception to July 1, 2023. STUDY SELECTION: In compliance with our PROSPERO registration (CRD42022347548), we selected articles comparing rSo2 measurements in adults either between racial groups or at different levels of skin pigmentation. Two independent reviewers conducted full-text reviews of all potentially relevant articles. DATA EXTRACTION: We extracted data on self-reported race or level of skin pigmentation and mean rSo2 values. DATA SYNTHESIS: Of the 11,495 unique records screened, two studies (n = 7,549) met our inclusion criteria for systematic review. Sun et al (2015) yielded significantly lower rSo2 values for African Americans compared with Caucasians, whereas Stannard et al (2021) found little difference between self-reported racial groups. This discrepancy is likely because Stannard et al (2021) used a NIRS platform which specifically purports to control for the effects of melanin. Several other studies that did not meet our inclusion criteria corroborated the notion that skin pigmentation results in lower rSo2 readings. CONCLUSIONS: Skin pigmentation likely results in attenuated rSo2 readings. However, the magnitude of this effect may depend on the specific NIRS platform used.

Application of the Single Source-Detector Separation Algorithm in Wearable Neuroimaging Devices: A Step toward Miniaturized Biosensor for Hypoxia Detection.

Most currently available wearable devices to noninvasively detect hypoxia use the spatially resolved spectroscopy (SRS) method to calculate cerebral tissue oxygen saturation (StO2). This study applies the single source-detector separation (SSDS) algorithm to calculate StO2. Near-infrared spectroscopy (NIRS) data were collected from 26 healthy adult volunteers during a breath-holding task using a wearable NIRS device, which included two source-detector separations (SDSs). These data were used to derive oxyhemoglobin (HbO) change and StO2. In the group analysis, both HbO change and StO2 exhibited significant change during a breath-holding task. Specifically, they initially decreased to minimums at around 10 s and then steadily increased to maximums, which were significantly greater than baseline levels, at 25-30 s (p-HbO < 0.001 and p-StO2 < 0.05). However, at an individual level, the SRS method failed to detect changes in cerebral StO2 in response to a short breath-holding task. Furthermore, the SSDS algorithm is more robust than the SRS method in quantifying change in cerebral StO2 in response to a breath-holding task. In conclusion, these findings have demonstrated the potential use of the SSDS algorithm in developing a miniaturized wearable biosensor to monitor cerebral StO2 and detect cerebral hypoxia.

Cerebral tissue oxygen desaturations and increased fractional oxygen extraction events vary by gestational age in preterm infants.

BACKGROUND AND OBJECTIVES: Cerebral tissue oxygen saturation (SctO2) and cerebral fractional tissue oxygen extraction (cFTOE) changes with GA in preterm infants. This study examines changes in frequency, duration, and severity of SctO2 desaturation and increased cFTOE with GA. STUDY DESIGN: The lower limit of normal SctO2, the event threshold, was calculated using a tolerance interval method with 95% confidence interval (CI) and 90% probability. Cerebral desaturation events were defined as: 1) a drop below event threshold for at least 30 s (s), 2) preceded by a period above the event threshold for at least 30s, and 3) followed by a period above the threshold for at least 60s. RESULTS: 86% of infants <28 wk experienced one or more SctO2 desaturation event compared to 57% in >28 wk, odds ratios (OR) 4.5 (CI:1.3-15.3, p = 0.016). The severity of SctO2 desaturation events decreases at a rate of 77.9 units per wk increase in GA (p < 0.001). 39.3% of infants <28 wk experienced one or more increased cFTOE events compared to 28.6% in >28 wk, OR 1.6 (CI:0.6-4.4, p = 0.35). The severity of increasing cFTOE events decreased by 69.7 units per wk increase in GA (p < 0.001). CONCLUSION: Cerebral tissue oxygen desaturation events decrease in frequency and severity with increasing GA. The severity of increased cFTOE episodes decrease with GA.

Reference ranges for regional cerebral tissue oxygen saturation and fractional oxygen extraction in neonates during immediate transition after birth.

OBJECTIVE: To define reference ranges for regional cerebral tissue oxygen saturation (crSO2) and regional cerebral fractional tissue oxygen extraction (cFTOE) during the first 15 minutes after birth in neonates requiring no medical support. STUDY DESIGN: The crSO2 was measured using near infrared spectroscopy (Invos 5100 cerebral/somatic oximeter monitor; Somanetics Corp, Troy, Michigan) during the first 15 minutes after birth for term and preterm neonates. The near infrared spectroscopy sensor was placed on the left forehead. Peripheral oxygen saturation and heart rate were continuously measured by pulse oximetry, and cFTOE was calculated. Neonates were excluded if they required any medical support. RESULTS: A total of 381 neonates were included: 82 term neonates after vaginal delivery, 272 term neonates after cesarean delivery, and 27 preterm neonates after cesarean delivery. In all neonates, median (10th-90th percentiles) crSO2 was 41% (23-64) at 2 minutes, 68% (45-85) at 5 minutes, 79% (65-90) at 10 minutes, and 77% (63-89) at 15 minutes of age. In all neonates, median (10th-90th percentiles) cFTOE was 33% (11-70) at 2 minutes, 21% (6-45) at 5 minutes, 15% (5-31) at 10 minutes, and 18% (7-34) at 15 minutes of age. CONCLUSION: We report reference ranges of crSO2 and cFTOE in neonates requiring no medical support during transition immediately after birth. The use of cerebral oxygenation monitoring and use of these reference ranges in neonates during transition may help to guide oxygen delivery and avoid cerebral hypo-oxygenation and hyperoxygenation.

Which Predictor, SctO2 or SstO2, Is more Sensitive for Postoperative Cognitive Dysfunction in Spine Surgery: A Prospective Observational Study?

OBJECTIVE: Patients undergoing spinal surgery in the prone position may experience venous stasis, often resulting in edema in dependent areas of the body, including the head, and increased postoperative cognitive dysfunction (POCD). Not only does POCD present challenges for post-operative care and recovery, it can also cause permanent damage to the patient's brain and increase mortality and social costs. We aimed to clarify the incidence of POCD in patients with hypertension after prone spine surgery and to further determine the association between intraoperative somatic tissue oxygen saturation (SstO2)/cerebral tissue oxygen saturation (SctO2) and POCD. METHODS: Patients with hypertension scheduled for open prone spine surgery from January 2020 to April 2021 were included in this single-center, prospective, observational study. SctO2 and SstO2 were monitored by near-infrared spectroscopy continuously throughout the surgery. The primary outcome was POCD assessed using the Mini-Mental Status Examination (MMSE). The association of SstO2 and SctO2 with POCD was evaluated with unadjusted analyses and multivariable logistic regression. RESULTS: One hundred and one of 112 identified patients were included, 28 (27.8%) of whom developed POCD. None of the investigated SctO2 indices were predictive of POCD. However, the patients with POCD had greater decreases in intraoperative absolute SstO2 and relative SstO2 than the patients without POCD (P = 0.037, P = 0.036). Moreover, three SstO2 indices were associated with POCD, including a greater absolute SstO2 decrease (P = 0.021), a greater relative SstO2 decrease (P = 0.032), and a drop below 90% of the baseline SstO2 (P = 0.002), independent of ASA III status, preoperative platelets and postoperative sepsis. In addition, there was no correlation between intraoperative SctO2 and intraoperative SstO2 or between their respective absolute declines. CONCLUSION: Twenty-eight (27.7%) of 101 patients developed POCD in patients with hypertension undergoing prone spine surgery, and intraoperative SstO2 is associated with POCD, whereas SctO2 shows no association with POCD. This study may initially provide a valuable new approach to the prevention of POCD in this population.