-
Biology May 2024Executing flight operations demand that military personnel continuously perform tasks that utilize low- and high-order cognitive functions. The autonomic nervous system...
Executing flight operations demand that military personnel continuously perform tasks that utilize low- and high-order cognitive functions. The autonomic nervous system (ANS) is crucial for regulating the supply of oxygen (O2) to the brain, but it is unclear how sustained cognitive loads of different complexities may affect this regulation. Therefore, in the current study, ANS responses to low and high cognitive loads in hypoxic and normoxic conditions were evaluated. The present analysis used data from a previously conducted, two-factor experimental design. Healthy subjects ( = 24) aged 19 to 45 years and located near Fort Novosel, AL, participated in the parent study. Over two, 2-h trials, subjects were exposed to hypoxic (14.0% O) and normoxic (21.0% O) air while simultaneously performing one, 15-min and one, 10-min simulation incorporating low- and high-cognitive aviation-related tasks, respectively. The tests were alternated across five, 27-min epochs; however, only epochs 2 through 4 were used in the analyses. Heart rate (HR), HR variability (HRV), and arterial O saturation were continuously measured using the Warfighter Monitor (Tiger Tech Solutions, Inc., Miami, FL, USA), a previously validated armband device equipped with electrocardiographic and pulse oximetry capabilities. Analysis of variance (ANOVA) regression models were performed to compare ANS responses between the low- and high-cognitive-load assessments under hypoxic and normoxic conditions. Pairwise comparisons corrected for familywise error were performed using Tukey's test within and between high and low cognitive loads under each environmental condition. Across epochs 2 through 4, in both the hypoxic condition and the normoxic condition, the high-cognitive-load assessment (MATB-II) elicited heightened ANS activity, reflected by increased HR (+2.4 ± 6.9 bpm) and decreased HRV (-rMSSD: -0.4 ± 2.7 ms and SDNN: -13.6 ± 14.6 ms). Conversely, low cognitive load (ADVT) induced an improvement in ANS activity, with reduced HR (-2.6 ± 6.3 bpm) and increased HRV (rMSSD: +1.8 ± 6.0 ms and SDNN: vs. +0.7 ± 6.3 ms). Similar observations were found for the normoxic condition, albeit to a lower degree. These within-group ANS responses were significantly different between high and low cognitive loads (HR: +5.0 bpm, 95% CI: 2.1, 7.9, < 0.0001; rMSSD: -2.2 ms, 95% CI: -4.2, -0.2, = 0.03; SDNN: -14.3 ms, 95% CI: -18.4, -10.1, < 0.0001) under the hypoxic condition. For normoxia, significant differences in ANS response were only observed for HR (+4.3 bpm, 95% CI: 1.2, 7.4, = 0.002). Lastly, only high cognitive loads elicited significant differences between hypoxic and normoxic conditions but just for SDNN (-13.3 ms, 95% CI, -17.5, -8.9, < 0.0001). Our study observations suggest that compared to low cognitive loads, performing high-cognitive-load tasks significantly alters ANS activity, especially under hypoxic conditions. Accounting for this response is critical, as military personnel during flight operations sustain exposure to high cognitive loads of unpredictable duration and frequency. Additionally, this is likely compounded by the increased ANS activity consequent to pre-flight activities and anticipation of combat-related outcomes.
PubMed: 38785825
DOI: 10.3390/biology13050343 -
The European Respiratory Journal Jun 2024https://bit.ly/4b8AFfw
https://bit.ly/4b8AFfw
Topics: Female; Humans; Male; Bias; Clinical Decision-Making; Oxygen; Oxygen Inhalation Therapy; Ethnicity; Racial Groups
PubMed: 38782465
DOI: 10.1183/13993003.02320-2023 -
Journal of Physiological Investigation Jan 2024Spinal cord injury is associated with spinal vascular disruptions that result in spinal ischemia and tissue hypoxia. This study evaluated the therapeutic efficacy of...
Spinal cord injury is associated with spinal vascular disruptions that result in spinal ischemia and tissue hypoxia. This study evaluated the therapeutic efficacy of normobaric hyperoxia on spinal cord oxygenation and circulatory function at the acute stage of cervical spinal cord injury. Adult male Sprague Dawley rats underwent dorsal cervical laminectomy or cervical spinal cord contusion. At 1-2 days after spinal surgery, spinal cord oxygenation was monitored in anesthetized and spontaneously breathing rats through optical recording of oxygen sensor foils placed on the cervical spinal cord and pulse oximetry. The arterial blood pressure, heart rate, blood gases, and peripheral oxyhemoglobin saturation were also measured under hyperoxic (50% O2) and normoxic (21% O2) conditions. The results showed that contused animals had significantly lower spinal cord oxygenation levels than uninjured animals during normoxia. Peripheral oxyhemoglobin saturation, arterial oxygen partial pressure, and mean arterial blood pressure are significantly reduced following cervical spinal cord contusion. Notably, spinal oxygenation of contused rats could be improved to a level comparable to uninjured animals under hyperoxia. Furthermore, acute hyperoxia elevated blood pressure, arterial oxygen partial pressure, and peripheral oxyhemoglobin saturation. These results suggest that normobaric hyperoxia can significantly improve spinal cord oxygenation and circulatory function in the acute phase after cervical spinal cord injury. We propose that adjuvant normobaric hyperoxia combined with other hemodynamic optimization strategies may prevent secondary damage after spinal cord injury and improve functional recovery.
Topics: Animals; Spinal Cord Injuries; Rats, Sprague-Dawley; Male; Hyperoxia; Rats; Oxygen; Spinal Cord; Cervical Cord; Blood Pressure; Oxyhemoglobins; Heart Rate
PubMed: 38780270
DOI: 10.4103/EJPI.EJPI-D-23-00003 -
Frontiers in Veterinary Science 2024This study aims to evaluate the respiratory rate-oxygenation index (ROX) and the ratio of pulse oximetry saturation (SpO) to the fraction of inspired oxygen (FiO)...
OBJECTIVE
This study aims to evaluate the respiratory rate-oxygenation index (ROX) and the ratio of pulse oximetry saturation (SpO) to the fraction of inspired oxygen (FiO) (SpO/FiO, [SF]) to determine whether these indices are predictive of outcome in dogs receiving high-flow nasal cannula oxygen therapy (HFNOT).
DESIGN
This is a prospective observational study.
SETTING
This study was carried out at two university teaching hospitals.
ANIMALS
In total, 88 dogs treated with HFNOT for hypoxemic respiratory failure due to various pulmonary diseases were selected.
MEASUREMENTS AND MAIN RESULTS
The ROX index was defined as the SF divided by the respiratory rate (RR). ROX and SF were calculated at baseline and for each hour of HFNOT. The overall success rate of HFNOT was 38% ( = 33/88). Variables predicting HFNOT success were determined using logistic regression, and the predictive power of each variable was assessed using the area under the receiver operating curve (AUC). ROX and SF were adequately predictive of HFNOT success when averaged over 0-16 h of treatment, with similar AUCs of 0.72 (95% confidence interval [CI] 0.60-0.83) and 0.77 (95% CI 0.66-0.87), respectively ( < 0.05). SF showed acceptable discriminatory power in predicting HFNOT outcome at 7 h, with an AUC of 0.77 (95% CI 0.61-0.93, = 0.013), and the optimal cutoff for predicting HFNC failure at 7 h was SF ≤ 191 (sensitivity 83% and specificity 76%).
CONCLUSION
These indices were easily obtained in dogs undergoing HFNOT. The results suggest that ROX and SF may have clinical utility in predicting the outcomes of dogs on HFNOT. Future studies are warranted to confirm these findings in a larger number of dogs in specific disease populations.
PubMed: 38774907
DOI: 10.3389/fvets.2024.1404195 -
Cost Effectiveness and Resource... May 2024Deep learning (DL) is a new technology that can assist prenatal ultrasound (US) in the detection of congenital heart disease (CHD) at the prenatal stage. Hence, an...
BACKGROUND
Deep learning (DL) is a new technology that can assist prenatal ultrasound (US) in the detection of congenital heart disease (CHD) at the prenatal stage. Hence, an economic-epidemiologic evaluation (aka Cost-Utility Analysis) is required to assist policymakers in deciding whether to adopt the new technology.
METHODS
The incremental cost-utility ratios (CUR), of adding DL assisted ultrasound (DL-US) to the current provision of US plus pulse oximetry (POX), was calculated by building a spreadsheet model that integrated demographic, economic epidemiological, health service utilization, screening performance, survival and lifetime quality of life data based on the standard formula: US screening data were based on real-world operational routine reports (as opposed to research studies). The DL screening cost of 145 USD was based on Israeli US costs plus 20.54 USD for reading and recording screens.
RESULTS
The addition of DL assisted US, which is associated with increased sensitivity (95% vs 58.1%), resulted in far fewer undiagnosed infants (16 vs 102 [or 2.9% vs 15.4%] of the 560 and 659 births, respectively). Adoption of DL-US will add 1,204 QALYs. with increased screening costs 22.5 million USD largely offset by decreased treatment costs (20.4 million USD). Therefore, the new DL-US technology is considered "very cost-effective", costing only 1,720 USD per QALY. For most performance combinations (sensitivity > 80%, specificity > 90%), the adoption of DL-US is either cost effective or very cost effective. For specificities greater than 98% (with sensitivities above 94%), DL-US (& POX) is said to "dominate" US (& POX) by providing more QALYs at a lower cost.
CONCLUSION
Our exploratory CUA calculations indicate the feasibility of DL-US as being at least cost-effective.
PubMed: 38773527
DOI: 10.1186/s12962-024-00550-3 -
Heliyon May 2024The COVID-19 pandemic in Latin America generated the need to develop low-cost, fast-manufacturing mechanical ventilators. The Universidad de La Sabana and the Fundacion...
BACKGROUND
The COVID-19 pandemic in Latin America generated the need to develop low-cost, fast-manufacturing mechanical ventilators. The Universidad de La Sabana and the Fundacion Neumologica Colombiana designed and manufactured the Unisabana-HERONS (USH) ventilator. Here, we present the preclinical and clinical study results to evaluate its effectiveness and safety characteristics in an animal model (Y and five patients with acute respiratory failure receiving mechanical ventilatory support for 24 h.
METHODS
The effectiveness and safety outcomes included maintaining arterial blood gases and pulse oximetry saturation (SpO2), respiratory pressures and volumes (during continuous monitoring) in the range of ARDS and lung-protective strategy goals, and the occurrence of barotrauma. A significance level of 0.05 was used for statistical tests. This clinical trial was registered on Clinicaltrials.gov (NCT04497623) and approved by the ethics committee.
RESULTS
Among patients treated with the Unisabana-HERONS, the most frequent causes of acute respiratory failure were pneumonia in 3/5 (60 %) and ARDS in 2/5 (40 %). During the treatment, the ventilatory parameters related to lung protection protocols were kept within the safety range, and vital signs and blood gas were stable. The percentage of time that the respiratory pressures or volumes were out of safety range were plateau pressure >30 cm H2O: 0.00 %; driving pressure >15 cm H2O: 0.06 %; mechanical power >15 J/min: 0.00 %; and Tidal volume >8 mL/kg: 0.00 %. There were no adverse events related to the ventilator. The usability questionnaire retrieved a median score for all items between 9 and 10 (best score: 10), indicating great ease of use.
CONCLUSION
The Unisabana-HERONS ventilator effectively provided adequate gas exchange and maintained the ventilatory parameters in the range of lung protection strategies in humans and an animal model. Furthermore, it is straightforward to use and is a low-cost medical device.
PubMed: 38756610
DOI: 10.1016/j.heliyon.2024.e30671 -
Cureus Apr 2024Background Pulse oximetry screening (POS) is acknowledged globally as a noninvasive method to detect critical congenital heart diseases (CCHDs) and respiratory...
Background Pulse oximetry screening (POS) is acknowledged globally as a noninvasive method to detect critical congenital heart diseases (CCHDs) and respiratory illnesses. However, its value for early diagnosis and treatment remains unrecognized in many hospitals with limited resources around the world. This study aimed to evaluate POS's application in CCHDs, persistent pulmonary hypertension (PPHN), and respiratory distress syndrome (RDS) for early diagnosis and its influence on clinical procedures in rural areas. Methods This prospective observational study included all eligible newborn infants in the regional neonatal unit of a community healthcare center. Their peripheral oxygen saturation was assessed at <24 hours and >24 hours after birth, in the right upper limb and either lower limb. An oxygen saturation of <95% or >3% difference between pre-ductal and post-ductal circulations was considered abnormal. All neonates with abnormal oxygen saturations at >24 hours after birth were subjected to another POS test within two hours of the last test. If the oxygen saturation was still abnormal, it was considered a positive POS test. The POS results were classified as oxygen saturation abnormal (<90%), abnormal (90-94%), and normal (≥95%). All neonates with a positive POS test were referred for echocardiography. Results Overall, 440 infants had documented POS results. A total of 65 (14.77%) infants had a positive POS test result, out of which 39 (8.86%) cases were diagnosed on further evaluation. Four neonates had CCHD (positive predictive value (PPV) = 6.15%), 26 had RDS (PPV = 40%), and nine had PPHN (PPV = 13.85%). Without any further delay, the doctor directed them all to a more advanced facility. Conclusion Our research showed that, in large-scale clinical settings, the addition of pulse oximetry to routine cardiac auscultation could be a reliable and feasible method to screen newborns for CCHD, PPHN, and RDS early on. Our research underscores the importance of implementing routine POS to detect CCHD, RDS, and PPHN in clinical practice.
PubMed: 38756257
DOI: 10.7759/cureus.58398 -
Veterinary Journal (London, England :... Jun 2024The postoperative period is critical for the development of complications, including hypoxemia. To detect hypoxemia early and provide appropriate care, continuous...
The postoperative period is critical for the development of complications, including hypoxemia. To detect hypoxemia early and provide appropriate care, continuous monitoring of saturation is necessary: pulse oximetry is an easily accessible and simple method for this purpose. However, a SpO cut-off value to detect hypoxemia in dogs recovering from general anesthesia is lacking in the veterinary literature. The objectives of this clinical study are to validate the room air SpO test (SpAT), to identify a cut-off value to discriminate hypoxemia (Phase 1), and to apply the SpAT to study the incidence of transient postoperative hypoxemia (TPH) (Phase 2) in dogs with healthy lungs recovering from general anesthesia. Phase 1: 87 dogs recovering from general anesthesia with an arterial line were included. After extubation, SpAT was performed simultaneously with arterial blood sampling. A PaO < 80 mmHg was considered hypoxemia. Phase 2: 654 dogs were enrolled. They underwent general anesthesia with different ventilation settings for different procedures. After extubation, dogs were classified as hypoxemic if the SpO was lower than the cut-off obtained in phase 1. Phase 1 showed that the SpO cut-off is < 95% (sensitivity 100%, specificity 97.4%; area under the curve, AUC = 0.996; 95% Confidence Interval = 0.944-1; P<0.0001). In Phase 2, 169 dogs were hypoxemic. Body Condition Score (BCS) > 3/5, dorsal recumbency, FiO 1, absence of Positive End-Expiratory Pressure (PEEP) had a significant odds ratio to induce TPH (5.8, 1.9, 3.7, 1.7, respectively). These results showed that SpO < 95% indicates PaO < 80 mmHg in dogs and TPH occurs in up to 28% of cases. Identification of associated risks could be useful to prevent and to increase awareness for monitoring and treatment.
Topics: Dogs; Animals; Hypoxia; Anesthesia, General; Oximetry; Dog Diseases; Male; Risk Factors; Female; Incidence; Postoperative Complications
PubMed: 38750813
DOI: 10.1016/j.tvjl.2024.106135 -
Clinical Ophthalmology (Auckland, N.Z.) 2024Diabetes mellitus (DM) causes different corneal changes that are associated with the severity of diabetic retinopathy. To identify the pathophysiological reasons for...
PURPOSE
Diabetes mellitus (DM) causes different corneal changes that are associated with the severity of diabetic retinopathy. To identify the pathophysiological reasons for this, corneal tomography and optical densitometry (COD) were combined with retinal oximetry.
METHODS
Patients with DM and healthy subjects were included in this pilot study. Spatially resolved corneal thickness and COD were assessed using the Pentacam HR (Oculus). The pachymetry difference (PAC) was calculated as an indicator of an increase in the peripheral corneal thickness. Oxygen saturation (SO) of the retinal vessels was measured using the Retinal Vessel Analyzer (Imedos Systems UG). Subsequently, the associations between corneal and retinal parameters were analyzed.
RESULTS
Data from 30 patients with DM were compared with those from 30 age-matched healthy subjects. In DM, arterial (P = 0.048) and venous (P < 0.001) SO levels were increased, and arteriovenous SO difference was decreased (P < 0.001). In patients, PAC was higher than that in healthy subjects (P < 0.05), indicating a stronger increase in peripheral corneal thickness. The COD was reduced in DM (P = 0.004). The PAC of concentric rings with a diameter of 4 mm (r = -0.404; P = 0.033) to 8 mm (r = -0.522; P = 0.004) was inversely correlated with the arteriovenous SO difference. Furthermore, PAC 4 mm was negatively associated with arterial SO (r = -0.389; P = 0.041), and the COD of the peripheral corneal areas correlated positive with arterial SO (COD total 10-12 mm: r = 0.408; P = 0.025).
CONCLUSION
These associations might indicate a common pathogenesis of corneal and retinal changes in DM, which could be caused by reduced oxygen supply, mitochondrial dysfunction, oxidative stress, and cytokine effects.
PubMed: 38737594
DOI: 10.2147/OPTH.S456020 -
Critical Care Explorations May 2024Near-infrared spectroscopy (NIRS) is a potentially valuable modality to monitor the adequacy of oxygen delivery to the brain and other tissues in critically ill... (Observational Study)
Observational Study Randomized Controlled Trial
OBJECTIVES
Near-infrared spectroscopy (NIRS) is a potentially valuable modality to monitor the adequacy of oxygen delivery to the brain and other tissues in critically ill patients, but little is known about the physiologic determinants of NIRS-derived tissue oxygen saturations. The purpose of this study was to assess the contribution of routinely measured physiologic parameters to tissue oxygen saturation measured by NIRS.
DESIGN
An observational sub-study of patients enrolled in the Role of Active Deresuscitation After Resuscitation-2 (RADAR-2) randomized feasibility trial.
SETTING
Two ICUs in the United Kingdom.
PATIENTS
Patients were recruited for the RADAR-2 study, which compared a conservative approach to fluid therapy and deresuscitation with usual care. Those included in this sub-study underwent continuous NIRS monitoring of cerebral oxygen saturations (SctO2) and quadriceps muscle tissue saturations (SmtO2).
INTERVENTION
Synchronized and continuous mean arterial pressure (MAP), heart rate (HR), and pulse oximetry (oxygen saturation, Spo2) measurements were recorded alongside NIRS data. Arterial Paco2, Pao2, and hemoglobin concentration were recorded 12 hourly. Linear mixed effect models were used to investigate the association between these physiologic variables and cerebral and muscle tissue oxygen saturations.
MEASUREMENTS AND MAIN RESULTS
Sixty-six patients were included in the analysis. Linear mixed models demonstrated that Paco2, Spo2, MAP, and HR were weakly associated with SctO2 but only explained 7.1% of the total variation. Spo2 and MAP were associated with SmtO2, but together only explained 0.8% of its total variation. The remaining variability was predominantly accounted for by between-subject differences.
CONCLUSIONS
Our findings demonstrated that only a small proportion of variability in NIRS-derived cerebral and tissue oximetry measurements could be explained by routinely measured physiologic variables. We conclude that for NIRS to be a useful monitoring modality in critical care, considerable further research is required to understand physiologic determinants and prognostic significance.
Topics: Humans; Spectroscopy, Near-Infrared; Critical Illness; Male; Female; Oxygen Saturation; Middle Aged; Aged; Oximetry; Monitoring, Physiologic; Brain; United Kingdom; Oxygen; Intensive Care Units; Quadriceps Muscle
PubMed: 38727717
DOI: 10.1097/CCE.0000000000001094