Can a Therapeutic Strategy for Hypotension Improve Cerebral Perfusion and Oxygenation in an Experimental Model of Hemorrhagic Shock and Severe Traumatic Brain Injury?

BACKGROUND: Restoration of brain tissue perfusion is a determining factor in the neurological evolution of patients with traumatic brain injury (TBI) and hemorrhagic shock (HS). In a porcine model of HS without neurological damage, it was observed that the use of fluids or vasoactive drugs was effective in restoring brain perfusion; however, only terlipressin promoted restoration of cerebral oxygenation and lower expression of edema and apoptosis markers. It is unclear whether the use of vasopressor drugs is effective and beneficial during situations of TBI. The objective of this study is to compare the effects of resuscitation with saline solution and terlipressin on cerebral perfusion and oxygenation in a model of TBI and HS. METHODS: Thirty-two pigs weighing 20-30 kg were randomly allocated into four groups: control (no treatment), saline (60 ml/kg of 0.9% NaCl), terlipressin (2 mg of terlipressin), and saline plus terlipressin (20 ml/kg of 0.9% NaCl + 2 mg of terlipressin). Brain injury was induced by lateral fluid percussion, and HS was induced through pressure-controlled bleeding, aiming at a mean arterial pressure (MAP) of 40 mmHg. After 30 min of circulatory shock, resuscitation strategies were initiated according to the group. The systemic and cerebral hemodynamic and oxygenation parameters, lactate levels, and hemoglobin levels were evaluated. The data were subjected to analysis of variance for repeated measures. The significance level established for statistical analysis was p < 0.05. RESULTS: The terlipressin and saline plus terlipressin groups showed an increase in MAP that lasted until the end of the experiment (p < 0.05). There was a notable increase in intracranial pressure in all groups after starting treatment for shock. Cerebral perfusion pressure and cerebral oximetry showed no improvement after hemodynamic recovery in any group. The groups that received saline at resuscitation had the lowest hemoglobin concentrations after treatment. CONCLUSIONS: The treatment of hypotension in HS with saline and/or terlipressin cannot restore cerebral perfusion or oxygenation in experimental models of HS and severe TBI. Elevated MAP raises intracranial pressure owing to brain autoregulation dysfunction caused by TBI.

Utility of continuous pulse CO-oximetry for hemoglobin monitoring in pediatric patients with solid organ injuries at level 1 trauma centers: A pilot study.

INTRODUCTION: Hemorrhage is a major cause of preventable death in injured children. Monitoring after admission often requires multiple blood draws, which have been shown to be stressful in pediatric patients. The Rainbow-7 device is a continuous pulse CO-oximeter that measures multiple wavelengths of light, permitting continuous estimation of the total hemoglobin (Hb) level. The purpose of this study was to evaluate the utility of the noninvasive Hb measurement for monitoring pediatric trauma patients admitted with solid organ injury. METHODS: This is a prospective, dual-center, observational trial for patients younger than age 18 years admitted to a Level I pediatric trauma center. Following admission, blood was routinely measured as per current solid organ injury protocols. Noninvasive Hb monitoring was initiated after admission. Time-synced data for Hb levels were compared with that taken using blood draws. Data were evaluated using bivariate correlation, linear regression, and Bland-Altman analysis. RESULTS: Over a 1-year period, 39 patients were enrolled. The mean ± SD age was 11 ± 3.8 years. Forty-six percent (n = 18) of patients were male. The mean ± SD Injury Severity Score was 19 ± 13. The average change in Hb levels between laboratory measurements was -0.34 ± 0.95 g/dL, and the average change in noninvasive Hb was -0.12 ± 1.0 g/dL per measurement. Noninvasive Hb values were significantly correlated with laboratory measurements ( p < 0.001). Trends in laboratory Hb measurements were highly correlated with changes in noninvasive levels ( p < 0.001). Bland-Altman analysis demonstrated similar deviation from the mean throughout the range of Hb values, but the differences between measurements were increased by anemia, African American race, and elevated shock index, pediatric age-adjusted score and Injury Severity Score. CONCLUSION: Noninvasive Hb values demonstrated correlation with measured Hb concentration as isolated measurements and trends, although results were affected by skin pigmentation, shock, and injury severity. Given the rapid availability of results and the lack of requirement of venipuncture, noninvasive Hb monitoring may be a valuable adjunct for pediatric solid organ injury protocols. Further study is required to determine its role in management. LEVEL OF EVIDENCE: Dianostic Test or Criteria; Level III.

Heart Disease Screening and False Hypoxemia in the Neonate.

BACKGROUND: Screening for congenital heart diseases by pulse oximetry is used for the initial assessment of the neonate. Variants of hemoglobin F can compromise light absorbance, inducing erroneous results. CASE REPORT: Two infants screened for congenital heart disease showed an asymptomatic low peripheral oxygen saturation. Arterial blood gases analysis revealed a normal arterial pressure of oxygen and oxygen saturation. More likely and/or severe causes of hypoxemia were ruled out. This "artifact" with SpO2-SaO2 dissociation, and after exclusion of other common etiologies of hypoxemia, raised the clinical suspicion of hemoglobinopathy. Hemoglobin molecular and genetic studies identified specific mutations in gamma chains from hemoglobin F, named hemoglobin F Sardinia. CONCLUSION: Hemoglobin F variants may result in low peripheral oxygen saturation readings by pulse oximetry, explaining the discordance in the clinical appearance and low peripheral oxygen saturation readings.

Assessment of Anastomotic Viability With Spectroscopic Real-time Oxygen Saturation Measurement in a Porcine Study.

OBJECTIVE: Anastomotic leakage (AL) is a severe complication following intestinal procedures. Intra.Ox™ by ViOptix Inc (Newark, CA, USA) is a novel, FDA-approved spectroscopic device which enables real-time measurement of mixed tissue oxygen saturation (StO2). Using a porcine model, this study explores the correlation between StO2 measurements and AL formation as well as investigates the applicability of Intra.Ox™ in the clinical setting. METHODS: Eleven female swine were divided into 3 groups to explore AL formation in different ischemic conditions. Group 1: 100% mesenteric-vascular ligation, n = 3; Group 2: 50% ligation, n = 5; Group 3: No mesenteric ligation, n = 3. StO2 at the anastomotic line was measured before and after vessel ligation and anastomosis. Measurements were taken at 6 distinct locations along afferent and efferent loops. AL was evaluated on postoperative day 5 by re-laparotomy. RESULTS: AL rate was 100%, 60% and 0% in groups 1, 2 and 3, respectively. Post-anastomotic StO2 in group 1 (22.9 ± 18.5%) and 2 (39.2 ± 20.1%) were significantly lower than in group 3 (53.1 ± 8.3%, p<.0001). Post-anastomotic StO2 readings ≤40% indicated AL potential with 100% sensitivity,+ 80% specificity, positive predictive value of 85.7% and negative predictive value of 100%. CONCLUSION: This study demonstrates the value of Intra.Ox™ in assessing local perfusion and indicate the association between low StO2 and AL by providing accurate, real-time, noninvasive tissue oxygenation measurements at anastomotic sites. Further studies are required to investigate the clinical application of this novel device in intestinal surgery.

Initial Treatment of High-Altitude Pulmonary Edema: Comparison of Oxygen and Auto-PEEP.

BACKGROUND: Improvement of oxygenation is the aim in the therapy of high-altitude pulmonary edema (HAPE). However, descent is often difficult and hyperbaric chambers, as well as bottled oxygen, are often not available. We compare Auto-PEEP (AP-Pat), a special kind of pursed lips breathing, against the application of bottled oxygen (O2-Pat) in two patients suffering from HAPE. METHODS: We compare the effect of these two different therapies on oxygen saturation measured by pulse oximetry (SpO2) over time. RESULT: In both patients SpO2 increased significantly from 65-70% to 95%. Above 80% this increase was slower in AP-Pat compared with O2-Pat. Therapy started immediately in AP-Pat but was delayed in O2-Pat because of organizational and logistic reasons. CONCLUSIONS: The well-established therapies of HAPE are always the option of choice, if available, and should be started as soon as possible. The advantage of Auto-PEEP is its all-time availability. It improves SpO2 nearly as well as 3 L/min oxygen and furthermore has a positive effect on oxygenation lasting for approximately 120 min after stopping. Auto-PEEP treatment does not appear inferior to oxygen treatment, at least in this cross-case comparison. Its immediate application after diagnosis probably plays an important role here.

A comprehensive review of cerebral oximetry in cardiac surgery.

BACKGROUND: Patients who undergo cardiac surgery are at increased risk of stroke, postoperative cognitive decline, and delirium. These neurocognitive complications have led to increased costs, intensive care unit stays, morbidity, and mortality. As a result, there is a significant push to mitigate any neurological complications in cardiac surgery patients. Near-infrared spectroscopy to measure regional cerebral oxygen saturations has gained consideration due to its noninvasive and user-friendly nature. Cerebral oximetry desaturations during cardiac surgery have been linked to an array of adverse clinical outcomes. However, the most effective intraoperative interventions to protect this vulnerable patient population have yet to be ascertained. AIM OF STUDY: To provide a comprehensive summary of the intraoperative management for cerebral oximetry desaturations during cardiac surgery. The review highlights clinical outcomes from cerebral oximetry use to quantify the importance of identifying cerebral desaturations during cardiac surgery. The review then interrogates possible interventions for cerebral oximetry desaturations in an effort to determine which interventions are most efficacious and to enlighten possible areas for further research. METHODS: A narrative review of randomized controlled trials, observational studies, and systematic reviews with metanalyses was performed through August 2021. RESULTS: There is significant heterogeneity among patient populations for which cerebral oximetry monitoring has been studied in cardiac surgery. Further, the definition of a clinically significant cerebral desaturation and the assessment of neurocognitive outcomes varied substantially across studies. As a result, metanalysis is challenging and few conclusions can be drawn. Cerebral oximetry use during cardiac surgery has not been associated with improvements in neurocognitive outcomes, morbidity, or mortality to date. The evidence to support a particular intervention for an acute desaturation is equivocal. CONCLUSIONS: Future research is needed to quantify a clinically significant cerebral desaturation and to determine which interventions for an acute desaturation effectively improve clinical outcomes.

Sulfohemoglobinemia secundaria a zopiclona. Casos clínicos / Sulfhemoglobinemia secondary to the use of zopiclone. Report of two cases

Sulfhemoglobin (SulfHb) is formed by hemoglobin (Hb) oxidation by sulfur compounds. Sulfhemoglobinemia is mainly associated with drugs or intestinal bacterial overgrowth. Patients present with central cyanosis, an abnormal pulse oximetry and normal arterial oxygen partial pressure. These features are shared with methemoglobinemia (MetHb) whose diagnosis requires an arterial co-oximetry. Depending on the device used, SulfHb may produce interference with this technique. We report two females aged 31 and 43 years, consulting at the emergency room with cyanosis. Both had a history of acute and chronic, high dose zopiclone ingestion. Pulse oximetry showed desaturation but with normal arterial oxygen partial pressure. Cardiac and pulmonary diseases were ruled out. Co-oximetry in two different analyzers showed interference or normal MetHb percentages. No other complications ensued, and cyanosis decreased over days. Since MetHb was discarded among other causes of cyanosis in a compatible clinical context, the diagnosis of sulfhemoglobinemia was made. The confirmatory method is not available in Chile. The presence of SulfHb is difficult to diagnose, confirmatory tests are not readily available, and it frequently interferes with arterial co-oximetry. This is attributed to a similar absorbance peak of both pigments in arterial blood. Venous co-oximetry can be useful in this context. SulfHb is a self-limited condition in most cases, however it must be differentiated from methemoglobinemia to avoid inappropriate treatments like methylene blue.

[Sulfhemoglobinemia secondary to the use of zopiclone. Report of two cases]. / Sulfohemoglobinemia secundaria a zopiclona. Casos clínicos.

Sulfhemoglobin (SulfHb) is formed by hemoglobin (Hb) oxidation by sulfur compounds. Sulfhemoglobinemia is mainly associated with drugs or intestinal bacterial overgrowth. Patients present with central cyanosis, an abnormal pulse oximetry and normal arterial oxygen partial pressure. These features are shared with methemoglobinemia (MetHb) whose diagnosis requires an arterial co-oximetry. Depending on the device used, SulfHb may produce interference with this technique. We report two females aged 31 and 43 years, consulting at the emergency room with cyanosis. Both had a history of acute and chronic, high dose zopiclone ingestion. Pulse oximetry showed desaturation but with normal arterial oxygen partial pressure. Cardiac and pulmonary diseases were ruled out. Co-oximetry in two different analyzers showed interference or normal MetHb percentages. No other complications ensued, and cyanosis decreased over days. Since MetHb was discarded among other causes of cyanosis in a compatible clinical context, the diagnosis of sulfhemoglobinemia was made. The confirmatory method is not available in Chile. The presence of SulfHb is difficult to diagnose, confirmatory tests are not readily available, and it frequently interferes with arterial co-oximetry. This is attributed to a similar absorbance peak of both pigments in arterial blood. Venous co-oximetry can be useful in this context. SulfHb is a self-limited condition in most cases, however it must be differentiated from methemoglobinemia to avoid inappropriate treatments like methylene blue.

The outcomes of using high oxygen concentration in pediatric patients.

Oxygen reserve index, available as part of Masimo Rainbow SET pulse oximetry, is a noninvasive and continuous variable intended to provide insight into a patient's oxygen status in the moderate hyperoxic range (PaO2 > 100 and ≤ 200 mm Hg), defined as a patient's oxygen "reserve". When used in conjunction with pulse oximetry, ORi extends the knowledge on a patient's oxygen status providing clinically important information helping to prevent hyperoxemia and hypoxemia. There are limited data on patients undergoing craniosynostosis surgery. Our primary goal was to evaluate the effects of different concentrations of inspiratory oxygen (FiO2) on patient oxygenation status by monitoring ORi. Thirty patients scheduled for craniosynostosis were included in this observational cohort study. Patients were randomized into two equal groups: Group 1 received a fraction of inspired oxygen of 0.8 and group 2 received a FiO2 of 0.6 during induction of anaesthesia. In addition to standard haemodynamic variables with ORi were recorded at baseline 1 min, 5 min, 60 min, and 120 min after intubation. Postoperative complications, length of stay in the intensive care unit and hospital were recorded. In total, 14 patients were evaluated in each group. Gender, age, BMI, ASA scores were similar between groups (p > 0.05). In Group 1, ORi values were significantly higher when compared to group 2 at baseline (0.86 ± 0.21 vs 0.45 ± 0.32, p = 0.001), one minute (0.61 ± 0.24 vs 0.27 ± 0.21, p = 0.001), and 5 min (0.34 ± 0.31 vs 0.10 ± 0.13, p = 0.033). High inspired oxygen concentration during induction of anesthesia in pediatric patients is associated with higher levels of ORi. Therefore, ORi may provide the means to safely reduce the inspired oxygen fraction during inhalational induction in paediatric patients.

Cerebral oximetry: a developing tool for monitoring cerebral oxygenation during cardiopulmonary resuscitation.

Despite improvements in cardiopulmonary resuscitation (CPR), survival and neurologic recovery after cardiac arrest remain very poor because of the impact of severe ischemia and subsequent reperfusion injury. As the likelihood of survival and favorable neurologic outcome decreases with increasing severity of ischemia during CPR, developing methods to measure the magnitude of ischemia during resuscitation, particularly cerebral ischemia, is critical for improving overall outcomes. Cerebral oximetry, which measures regional cerebral oxygen saturation (rSO2 ) by near-infrared spectroscopy, has emerged as a potentially beneficial marker of cerebral ischemia during CPR. In numerous preclinical and clinical studies, higher rSO2 during CPR has been associated with improved cardiac arrest survival and neurologic outcome. In this narrative review, we summarize the scientific rationale and validation of cerebral oximetry across populations and pathophysiologic states, discuss the evidence surrounding its use to predict return of spontaneous circulation, rearrest, and neurologic outcome, and provide suggestions for incorporation of cerebral oximetry into CPR practice.

Validation of the Withings ScanWatch as a Wrist-Worn Reflective Pulse Oximeter: Prospective Interventional Clinical Study.

BACKGROUND: A decrease in the level of pulse oxygen saturation as measured by pulse oximetry (SpO2) is an indicator of hypoxemia that may occur in various respiratory diseases, such as chronic obstructive pulmonary disease (COPD), sleep apnea syndrome, and COVID-19. Currently, no mass-market wrist-worn SpO2 monitor meets the medical standards for pulse oximeters. OBJECTIVE: The main objective of this monocentric and prospective clinical study with single-blind analysis was to test and validate the accuracy of the reflective pulse oximeter function of the Withings ScanWatch to measure SpO2 levels at different stages of hypoxia. The secondary objective was to confirm the safety of this device when used as intended. METHODS: To achieve these objectives, we included 14 healthy participants aged 23-39 years in the study, and we induced several stable plateaus of arterial oxygen saturation (SaO2) ranging from 100%-70% to mimic nonhypoxic conditions and then mild, moderate, and severe hypoxic conditions. We measured the SpO2 level with a Withings ScanWatch on each participant's wrist and the SaO2 from blood samples with a co-oximeter, the ABL90 hemoximeter (Radiometer Medical ApS). RESULTS: After removal of the inconclusive measurements, we obtained 275 and 244 conclusive measurements with the two ScanWatches on the participants' right and left wrists, respectively, evenly distributed among the 3 predetermined SpO2 groups: SpO2≤80%, 80%

Does the application of Opsite⋄ Flexigrid⋄ occlude the oxygen saturation readings in healthy individuals using the moorVMS-OXY machine?

BACKGROUND: A proportion of people who have been diagnosed with peripheral arterial disease and diabetes mellitus will be susceptible to chronic wounds. Oxygen is vital for wound healing, so oxygen measurements should to be taken as predictive values for wound healing in patients. When measuring oxygen at the wound bed, there is potentially a risk of cross-infection if no protective barrier is used; and skin stripping if an adhesive barrier is used on the wound bed. This cross sectional within subject repeated measures pilot study, aims to determine if the application of opsite film, as an infection control measure, in one or two layers, impacts on tissue oxygenation readings obtained when using the MoorVMS-OXY. METHODS: Mean oxygen saturation percentages were measured from 29 limbs of 18 healthy participants. Oxygen saturation was measured for 20 s and analysed at the first metatarsophalangeal joint using no film, one and two layers using the MoorVMS-OXY. A one-way repeated ANOVA with a Bonferroni post hoc test was performed to test for statistically significant differences between the values of the three parameters and multiple pairwise comparisons was completed. RESULTS: Amongst the three layers, there was a statistically significant difference in oxygen saturation between the two layers of Opsite Flexigrid and none; and also between the two layers of Flexigrid and single layer (p < 0.05). It was also established that there was no statistically significant difference between the single layer of Opsite Flexigrid and no Flexigrid layer (p > 0.05). CONCLUSIONS: The results imply that one layer of Opsite Flexigrid is a suitable protective barrier to use when establishing capillary bed oxygen perfusion with the MoorVMS-OXY. However, the application of two Opsite Flexigrid layers, to prevent skin stripping, decreases the recorded values of oxygen saturation percentages significantly, therefore providing inaccurate results. Indicating that a double layer cannot be used over ulceration sites if measuring oxygen levels at the wound bed.

Oxygen systems to improve clinical care and outcomes for children and neonates: A stepped-wedge cluster-randomised trial in Nigeria.

BACKGROUND: Improving oxygen systems may improve clinical outcomes for hospitalised children with acute lower respiratory infection (ALRI). This paper reports the effects of an improved oxygen system on mortality and clinical practices in 12 general, paediatric, and maternity hospitals in southwest Nigeria. METHODS AND FINDINGS: We conducted an unblinded stepped-wedge cluster-randomised trial comparing three study periods: baseline (usual care), pulse oximetry introduction, and stepped introduction of a multifaceted oxygen system. We collected data from clinical records of all admitted neonates (<28 days old) and children (28 days to 14 years old). Primary analysis compared the full oxygen system period to the pulse oximetry period and evaluated odds of death for children, children with ALRI, neonates, and preterm neonates using mixed-effects logistic regression. Secondary analyses included the baseline period (enabling evaluation of pulse oximetry introduction) and evaluated mortality and practice outcomes on additional subgroups. Three hospitals received the oxygen system intervention at 4-month intervals. Primary analysis included 7,716 neonates and 17,143 children admitted during the 2-year stepped crossover period (November 2015 to October 2017). Compared to the pulse oximetry period, the full oxygen system had no association with death for children (adjusted odds ratio [aOR] 1.06; 95% confidence interval [CI] 0.77-1.46; p = 0.721) or children with ALRI (aOR 1.09; 95% CI 0.50-2.41; p = 0.824) and was associated with an increased risk of death for neonates overall (aOR 1.45; 95% CI 1.04-2.00; p = 0.026) but not preterm/low-birth-weight neonates (aOR 1.30; 95% CI 0.76-2.23; p = 0.366). Secondary analyses suggested that the introduction of pulse oximetry improved oxygen practices prior to implementation of the full oxygen system and was associated with lower odds of death for children with ALRI (aOR 0.33; 95% CI 0.12-0.92; p = 0.035) but not for children, preterm neonates, or neonates overall (aOR 0.97, 95% CI 0.60-1.58, p = 0.913; aOR 1.12, 95% CI 0.56-2.26, p = 0.762; aOR 0.90, 95% CI 0.57-1.43, p = 0.651). Limitations of our study are a lower-than-anticipated power to detect change in mortality outcomes (low event rates, low participant numbers, high intracluster correlation) and major contextual changes related to the 2016-2017 Nigerian economic recession that influenced care-seeking and hospital function during the study period, potentially confounding mortality outcomes. CONCLUSIONS: We observed no mortality benefit for children and a possible higher risk of neonatal death following the introduction of a multifaceted oxygen system compared to introducing pulse oximetry alone. Where some oxygen is available, pulse oximetry may improve oxygen usage and clinical outcomes for children with ALRI. TRIAL REGISTRATION: Australian New Zealand Clinical Trials Registry: ACTRN12617000341325.

Reducing Alarm Fatigue in Two Neonatal Intensive Care Units through a Quality Improvement Collaboration.

OBJECTIVE: To reduce nonactionable oximeter alarms by 80% without increasing time infants were hypoxemic (oxygen saturation [SpO2] ≤ 80%) or hyperoxemic (SpO2 > 95% while on supplemental oxygen). STUDY DESIGN: In 2015, a multidisciplinary team at Connecticut Children's Medical Center initiated a quality improvement project to reduce nonactionable oximeter alarms in two referral neonatal intensive care units (NICUs). Changes made through improvement cycles included reduction of the low oximeter alarm limit for specific populations, increased low alarm delay, development of postmenstrual age-based alarm profiles, and updated bedside visual reminders. Manual alarm tallies and electronic SpO2 data were collected throughout the project. RESULTS: Alarm tallies were collected for 158 patient care hours with SpO2 data available for 138 of those hours. Mean number of total nonactionable alarms per patient per hour decreased from 9 to 2 (78% decrease) and the mean number of nonactionable low alarms per patient per hour decreased from 5 to 1 (80% decrease). No change was noted in the balancing measures of percentage time with SpO2 ≤ 80% (mean 4.3%) or SpO2 > 95% (mean 23.7%). CONCLUSION: Through small changes in oximeter alarm settings, including revision of alarm limits, alarm delays, and age-specific alarm profiles, our NICUs significantly reduced nonactionable alarms without increasing hypoxemia.

Magnetic resonance imaging (MRI) induced 'hypoxia artifacts' on pulse oximetry: how reliable are MRI compatible monitoring devices?

Distinguishing a monitoring artifact requires expertise and adeptness. This can be practically challenging during the course of an anesthetic. We report a case, wherein we experienced episodes of aberrant pulse-oximeter values suggestive of desaturation with normal waveforms, occurring during a particular sequence of magnetic resonance imaging (MRI) performed under general anesthesia, which in fact was an artifact induced by the 3 T MRI during the diffusion tensor imaging sequence.

Comparison of nasal and forehead oximetry accuracy and pressure injury in critically ill patients.

BACKGROUND: In critically ill patients, clinicians can have difficulty obtaining accurate oximetry measurements. OBJECTIVE: To compare the accuracy of nasal alar and forehead sensor measurements and incidence of pressure injury. METHODS: 43 patients had forehead and nasal alar sensors applied. Arterial samples were obtained at 0, 24, and 120 hours. Oxygen saturations measured by co-oximetry were compared to sensor values. Skin was assessed every 8 hours. RESULTS: Oxygen saturations ranged from 69.8%-97.8%, with 18% of measures < 90%. Measurements were within 3% of co-oximetry values for 54% of nasal alar compared to 35% of forehead measurements. Measurement failures occurred in 6% for nasal alar and 22% for forehead. Three patients developed a pressure injury with the nasal alar sensor and 13 patients developed a pressure injury with the forehead sensor (χ2 = 7.68; p = .006). CONCLUSIONS: In this group of patients with decreased perfusion, nasal alar sensors provided a potential alternative for continuous monitoring of oxygen saturation.

An observational study of the optimal placement of a cerebral oximeter probe to avoid the frontal sinus in children.

The frontal sinus is an airspace behind the brow ridge in the skull and can affect the accuracy of the regional cerebral oxygen saturation measurements. We evaluated the optimal location for placement of a cerebral oximeter probe while avoiding the frontal sinus in pediatric patients. This retrospective observational study included 203 pediatric patients aged 3-17 years who had undergone brain computed tomography from November 2010 to December 2015. The patients were divided into five subgroups based on their age. The frontal sinus height was measured from the superior orbital rim. Pneumatization of the frontal sinus was not visible in 78% (3-5 years) and 22% (6-8 years) of the patients. The mean (SD) of the frontal sinus height was 5.9 (3.4), 9.5 (4.1), 14.0 (6.2) 18.6 (8.4), and 21.1 (7.9) mm in the 3-5, 6-8, 9-11, 12-14, and 15-17 year age-groups, respectively. Age was positively correlated with the frontal sinus height (r = 0.61, P < 0.001, 95% confidence interval [CI] 0.513-0.688). A frontal sinus height shorter than 1, 2, and 3 cm were seen in 10 of 11 (91%), 69 of 74 (94%), and 108 of 118 (90%) patients aged 3-5, 6-10, and 11-17 years, respectively. When oximeter probes are applied in pediatric patients, placement based on age can help avoid the frontal sinus.