End-tidal Carbon Dioxide Research Articles

New models for prediction of postoperative pulmonary complications in lung resection candidates.

In recent years, ventilatory efficiency (minute ventilation (V'E)/carbon dioxide production (V'CO2 ) slope) and partial pressure of end-tidal carbon dioxide (P ETCO2 ) have emerged as independent predictors of postoperative pulmonary complications (PPC). Single parameters may give only partial information regarding periprocedural hazards. Accordingly, our aim was to create prediction models with improved ability to stratify PPC risk in patients scheduled for elective lung resection surgery. This post hoc analysis was comprised of consecutive lung resection candidates from two prior prospective trials. All individuals completed pulmonary function tests and cardiopulmonary exercise testing (CPET). Logistic regression analyses were used for identification of risk factors for PPC that were entered into the final risk prediction models. Two risk models were developed; the first used rest P ETCO2 (for patients with no available CPET data), the second used V'E/ V'CO2 slope (for patients with available CPET data). Receiver operating characteristic analysis with the De-Long test and area under the curve (AUC) were used for comparison of models. The dataset from 423 patients was randomly split into the derivation (n=310) and validation (n=113) cohorts. Two final models were developed, both including sex, thoracotomy, "atypical" resection and forced expiratory volume in 1 s/forced vital capacity ratio as risk factors. In addition, the first model also included rest P ETCO2 , while the second model used V'E/V'CO2 slope from CPET. AUCs of risk scores were 0.795 (95% CI: 0.739-0.851) and 0.793 (95% CI: 0.737-0.849); both p<0.001. No differences in AUCs were found between the derivation and validation cohorts. We created two multicomponental models for PPC risk prediction, both having excellent predictive properties.

Using modified Fenn diagrams to assess ventilatory acclimatization during ascent to high altitude: Effect of acetazolamide.

High altitude (HA) ascent imposes systemic hypoxia and associated risk of acute mountain sickness. Acute hypoxia elicits a hypoxic ventilatory response (HVR), which is augmented with chronic HA exposure (i.e., ventilatory acclimatization; VA). However, laboratory-based HVR tests lack portability and feasibility in field studies. As an alternative, we aimed to characterize area under the curve (AUC) calculations on Fenn diagrams, modified by plotting portable measurements of end-tidal carbon dioxide ( ) against peripheral oxygen saturation ( ) to characterize and quantify VA during incremental ascent to HA (n=46). Secondarily, these participants were compared with a separate group following the identical ascent profile whilst self-administering a prophylactic oral dose of acetazolamide (Az; 125mg BID; n=20) during ascent. First, morning and measurements were collected on 46 acetazolamide-free (NAz) lowland participants during an incremental ascent over 10days to 5160m in the Nepal Himalaya. AUC was calculated from individually constructed Fenn diagrams, with a trichotomized split on ranked values characterizing the smallest, medium, and largest magnitudes of AUC, representing high (n=15), moderate (n=16), and low (n=15) degrees of acclimatization. After characterizing the range of response magnitudes, we further demonstrated that AUC magnitudes were significantly smaller in the Az group compared to the NAz group (P=0.0021), suggesting improved VA. These results suggest that calculating AUC on modified Fenn diagrams has utility in assessing VA in large groups of trekkers during incremental ascent to HA, due to the associated portability and congruency with known physiology, although this novel analytical method requires further validation in controlled experiments. HIGHLIGHTS: What is the central question of this study? What are the characteristics of a novel methodological approach to assess ventilatory acclimatization (VA) with incremental ascent to high altitude (HA)? What is the main finding and its importance? Area under the curve (AUC) magnitudes calculated from modified Fenn diagrams were significantly smaller in trekkers taking an oral prophylactic dose of acetazolamide compared to an acetazolamide-free group, suggesting improved VA. During incremental HA ascent, quantifying AUC using modified Fenn diagrams is feasible to assess VA in large groups of trekkers with ascent, although this novel analytical method requires further validation in controlled experiments.

Low intraoperative end-tidal carbon dioxide levels are associated with improved recurrence-free survival after elective colorectal cancer surgery

Study objectiveHigher levels of carbon dioxide (CO2) increase the invasive abilities of colon cancer cells in vitro. Studies assessing target values for end-tidal CO2 concentrations (EtCO2) to improve surgical outcome after colorectal cancer surgery are lacking. Therefore, we evaluated whether intraoperative EtCO2 was associated with differences in recurrence-free survival after elective colorectal cancer (CRC) surgery. DesignSingle center, retrospective analysis. SettingAnesthesia records, surgical databases and hospital information system of a tertiary university hospital. PatientsWe analyzed 528 patients undergoing elective resection of colorectal cancer at Heidelberg University Hospital between 2009 and 2018. InterventionsNone. MeasurementsIntraoperative mean EtCO2 values were calculated. The study cohort was equally stratified into low-and high-EtCO2 groups. The primary endpoint measure was recurrence-free survival until last known follow-up. Groups were compared using Kaplan-Meier analysis. Cox-regression analysis was used to control for covariates. Sepsis, reoperations, surgical site infections and cardiovascular events during hospital stay, and overall survival were secondary outcomes. Main resultsMean EtCO2 was 33.8 mmHg ±1.2 in the low- EtCO2 group vs. 37.3 mmHg ±1.6 in the high-EtCO2 group. Median follow-up was 3.8 (Q1-Q3, 2.5–5.1) years. Recurrence-free survival was higher in the low-EtCO2 group (log-rank-test: p = .024). After correction for confounding factors, lower EtCO2 was associated with increased recurrence-free survival (HR = 1.138, 95%-CI:1.015–1.276, p = .027); the hazard for the primary outcome decreased by 12.1% per 1 mmHg decrease in mean EtCO2. 1-year and 5-year survival was also higher in the low-EtCO2 group. We did not find differences in the other secondary endpoints. ConclusionsLower intraoperative EtCO2 target values in CRC surgery might benefit oncological outcome and should be evaluated in confirmative studies.

Computer vision digitization of smartphone images of anesthesia paper health records from low-middle income countries

BackgroundIn low-middle income countries, healthcare providers primarily use paper health records for capturing data. Paper health records are utilized predominately due to the prohibitive cost of acquisition and maintenance of automated data capture devices and electronic medical records. Data recorded on paper health records is not easily accessible in a digital format to healthcare providers. The lack of real time accessible digital data limits healthcare providers, researchers, and quality improvement champions to leverage data to improve patient outcomes. In this project, we demonstrate the novel use of computer vision software to digitize handwritten intraoperative data elements from smartphone photographs of paper anesthesia charts from the University Teaching Hospital of Kigali. We specifically report our approach to digitize checkbox data, symbol-denoted systolic and diastolic blood pressure, and physiological data.MethodsWe implemented approaches for removing perspective distortions from smartphone photographs, removing shadows, and improving image readability through morphological operations. YOLOv8 models were used to deconstruct the anesthesia paper chart into specific data sections. Handwritten blood pressure symbols and physiological data were identified, and values were assigned using deep neural networks. Our work builds upon the contributions of previous research by improving upon their methods, updating the deep learning models to newer architectures, as well as consolidating them into a single piece of software.ResultsThe model for extracting the sections of the anesthesia paper chart achieved an average box precision of 0.99, an average box recall of 0.99, and an mAP0.5-95 of 0.97. Our software digitizes checkbox data with greater than 99% accuracy and digitizes blood pressure data with a mean average error of 1.0 and 1.36 mmHg for systolic and diastolic blood pressure respectively. Overall accuracy for physiological data which includes oxygen saturation, inspired oxygen concentration and end tidal carbon dioxide concentration was 85.2%.ConclusionsWe demonstrate that under normal photography conditions we can digitize checkbox, blood pressure and physiological data to within human accuracy when provided legible handwriting. Our contributions provide improved access to digital data to healthcare practitioners in low-middle income countries.

Association of initial assessment variables and mortality in severe pediatric traumatic brain injury

BackgroundPredictive scales have been used to prognosticate long-term outcomes of traumatic brain injury (TBI), but gaps remain in predicting mortality using initial trauma resuscitation data. We sought to evaluate the...

Multi-modal Magnetic Resonance Imaging to Assess Cerebrovascular Function in Atrial Fibrillation Patients

Atrial fibrillation (AF) is associated with an increased risk of cognitive decline, dementia, and stroke. Low cerebral blood flow (CBF) and low cerebrovascular carbon dioxide reactivity (CVRCO2) are associated with poor brain health outcomes. In the current study we employed magnetic resonance imaging (MRI) to quantify resting CBF and CVRCO2 in patients with AF and age-matched normal sinus rhythm (NSR) controls. We hypothesised that both resting CBF and CVRCO2 would be lower in patients with AF. Patients with AF (n=11, 65±14 years, 2 women) and NSR (n=12, 63±9 years, 7 women) underwent arterial spin labelling (ASL) at rest, and blood oxygen level-dependent (BOLD) MRI during a single-step increase in partial pressure of carbon dioxide (measured by end-tidal carbon dioxide (PETCO2)) induced by changing the fraction of inspired CO2 to 5% (21% O2, balance N2). Region of interest time courses were extracted with grey matter, middle cerebral artery, and posterior cerebral artery territory masks. CVRCO2 was defined as the percentage change (%Δ) in BOLD signal vs %Δ in PETCO2. Baseline CBF was not different between NSR and AF in grey matter (62±17 vs. 58±10 ml/min/100g, respectively; p=0.226), middle cerebral artery (59±16 vs. 56±14 ml/min/100g; p=0.361) and posterior cerebral artery (61±17 vs 53±15 ml/min/100g; p=0.138) territories. BOLD-derived CVRC02 was not different between NSR and AF groups in grey matter (0.11±0.04 vs. 0.12±0.03 %ΔBOLD/%ΔmmHg, respectively; p=0.372), middle cerebral artery (0.09±0.04 vs. 0.10±0.03 %ΔBOLD/%ΔmmHg; p=0.405) and posterior cerebral artery (0.13±0.04 vs. 0.14±0.05 %ΔBOLD/%ΔmmHg; p=0.367) territories. Collectively, these pilot data suggest that MRI-derived cerebrovascular CO2 responsiveness is not different in patients with AF and age-matched NSR controls that have similar resting CBF. Further investigations are required to extend these preliminary findings to a larger cohort to fully elucidate the effects of AF on cerebrovascular function. Support provided by the Royal Society of New Zealand Te Apārangi Marsden Fund (19-UOA-170). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cerebrovascular Conductance Responses to Carbon Dioxide are Attenuated by the Presence of Hypertension in Patients with Atrial Fibrillation

The cerebral vasculature is highly sensitive to carbon dioxide (CO2) and cerebrovascular CO2 reactivity (CVRCO2) is widely used to index cerebral vascular health. Some studies have shown that both atrial fibrillation (AF) and hypertension (HTN) are independently associated with reduced CVRCO2. However, it is unknown if these effects on CVRCO2 are synergistic when AF and HTN are present together. In this study we tested the hypothesis that CVRCO2 was lower in patients with both AF and HTN (AF+HTN) compared to normotensive patients with AF. Transcranial Doppler ultrasound was used to measure middle cerebral artery blood velocity (MCA Vm) in AF (n=31) and AF+HTN (n=57) during stepped increases and decreases in end-tidal carbon dioxide (PETCO2). The ratio of MCA Vm and mean arterial pressure (MAP) was defined as cerebrovascular conductance index (CVCi). CVRCO2 was taken as the linear slope for MCA Vm and MCA CVCi versus PETCO2. As expected, baseline MAP was higher in AF+HTN than AF (107±9 vs. 98±9 mmHg, respectively; p&lt;0.001). Baseline MCA Vm was numerically lower in AF+HTN than AF, but this did not reach statistical significance (50 [44-60] vs. 52 [45-63] cm.s−1, respectively; p=0.075), while baseline CVCi was lower in AF+HTN compared to AF (0.46 [0.42-0.57] vs. 0.54 [0.44-0.63] cm.s−1.mmHg−1; p&lt;0.001). MCA Vm CVRCO2 was not different between groups (1.70 [1.47-2.19] and 1.74 [1.54-2.52] cm/s/mmHg−2 for AF+HTN and AF, respectively; p=0.221), whereas MCA CVCi CVRCO2 was 13% lower in AF+HTN compared to AF (0.013 ± 0.004 vs. 0.015 ± 0.005 cm.s.mmHg−2; p=0.047). Stepwise linear regression analysis identified that cardiac rhythm during data acquisition (AF or normal sinus rhythm) was a predictor of baseline MCA CVCi and MCA CVCi CVRCO2. In summary, our results demonstrate impaired MCA CVCi CVRCO2 in AF+HTN and suggest that the presence of HTN worsens cerebrovascular function in AF. Such cerebrovascular alterations may be important for the development of cognitive decline and diminished brain health in AF. Funding provided by Bristol-Myers Squibb/Pfizer Alliance Project Grant (CV185-481), British Heart Foundation Project Grant (PG/15/45/31579) and the National Institute of Health Research Clinical Research Network (NIHR CRN). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Cerebrovascular Carbon Dioxide Reactivity Is Intact in Chronic Kidney Disease

Introduction: Chronic Kidney Disease (CKD) is associated with a substantially elevated risk of stroke. One factor that might contribute to this heightened risk is an impairment in cerebrovascular carbon dioxide reactivity (CVR), the mechanism through which cerebral vessels dilate and constrict in response to fluctuations in arterial carbon dioxide tension (PaCO2). CVR is known to be impaired in other chronic disease states associated with stroke risk; thus, we aimed to determine if CVR is also impaired in patients with moderate to severe CKD (stages III-IV). We hypothesized that CKD patients would exhibit impaired CVR compared to a control group (CON) matched for age, hypertension, and diabetes status. Methods: 9 CKD participants (age=56 ± 17y, eGFR=39 ± 4 mL/min/1.73m2), and 9 CON participants (age=61 ± 6y) underwent a single experimental protocol in which PaCO2 was manipulated via 2-min of hypercapnia (5% CO2) followed by 2-min hypocapnia (voluntary hyperventilation) while heart rate (via ECG), blood pressure (via finger photoplethysmography), middle cerebral artery blood velocity (MCAv; via transcranial Doppler ultrasonography), and end-tidal carbon dioxide (etCO2) were measured continuously. CVR was quantified as the slope of the linear relationship between breath-by-breath etCO2 and MCAv while accounting for blood pressure as a covariate. Hyper-, hypo- and, integrated (hyper + hypo) CVR was compared between groups via a 2-tailed, unpaired T-test. Results: We observed no differences in CVR between groups. Hypercapnic CVR: CKD = 1.4 ± 1.0 cm/s/mmHg, CON = 1.5 ± 0.8 cm/s/mmHg, Hypocapnic CVR: CKD = 1.5 ± 0.8 cm/s/mmHg, CON = 1.5 ± 0.8 cm/s/mmHg, Integrated CVR: CKD = 1.7 ± 1.2 cm/s/mmHg, CON = 1.7 ± 0.6 cm/s/mmHg, P ≥ 0.90. Conclusions: Contrary to our hypothesis, CVR remains intact in CKD stages III-IV. These findings suggest that other mechanisms contribute to the elevated stroke risk observed in this population. Funding: This work was supported by the American Heart Association (Career Development Award #929040, PI: Sprick), and NIH grants R01HL135183 and R33AT010457. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Can end-tidal CO2 measurement replace arterial partial CO2 in emergency department respiratory distress management?

ObjectiveTo assess the feasibility of using end-tidal carbon dioxide (EtCO2) as a non-invasive substitute for partial pressure of arterial carbon dioxide (PaCO2) in emergency department (ED) triage and follow-up, and to explore the potential of partial pressure of venous carbon dioxide (PvCO2) as an alternative to PaCO2. DesignProspective cross-sectional study. SettingTertiary university hospital. Patients or participants97 patients presenting with acute respiratory distress to the ED. InterventionsEtCO2, arterial blood gases, and venous blood gases measured at admission (0 min), 60 min, and 120 min. Main variables of interestCO2 levels. ResultsAmong 97 patients (mean age: 70.93 ± 9.6 years; 60.8% male), EtCO2 > 45 mmHg at admission showed strong positive correlations with PaCO2 and PvCO2 (r = 0.844, r = 0.803; p < 0.001, respectively). Significant positive correlation was observed between 60-min EtCO2 and PaCO2 (r = 0.729; p < 0.001). Strong correlation between PaCO2 and PvCO2 at 120 min when EtCO2 > 45 mmHg (r = 0.870; p < 0.001). EtCO2 was higher in hospitalized patients compared to discharged ones. ConclusionsEtCO2 appears promising as a substitute for PaCO2 in ED patients with acute respiratory distress within the initial two hours of treatment. Venous blood gas sampling offers a less invasive alternative to arterial sampling, facilitating simultaneous blood tests.

Comparative Evaluation of Effectiveness of Two-handed E-C Clamp Technique versus V-E Technique in Patients with Predicted Difficult Mask Ventilation

Abstract Background: The skill of bag mask ventilation (BMV) remains pivotal during airway management for maintenance of oxygenation in apneic unconscious patients. Two-handed BMV techniques viz., the traditional E-C and V-E have been proven to be superior to one-handed techniques in optimizing BMV in difficult mask ventilation (DMV) scenarios. Aims and Objectives: This study aimed to compare the effectiveness of these two techniques of BMV in adult patients with predicted DMV. Methods: Four hundred ASA I-III adult patients with predictors of DMV received BMV after induction of anaesthesia using E-C clamp and V-E techniques in a randomized cross-over manner. Ventilator was set to VCV mode delivering tidal volume of 7 ml/kg, respiratory rate of 10 breaths per minute, and no PEEP. The primary outcome was exhaled tidal volume (Vte) and secondary outcomes analysed included air-leak, peak inspiratory pressure (PIP), end-tidal carbon dioxide (EtCO2), minute ventilation (MV), plateau pressure and SpO2. Results: Two-handed V-E technique generated significantly higher mean Vte of 377.83 ± 58.43 ml as compared to two-handed E-C technique (303.26 ± 103.34 ml). The air-leak was found to be significantly more with E-C technique (131.05 ml ± 100.95 ml) as compared to V-E technique (59.08 ± 49.62 ml). Higher EtCO2, MV with concomitant lower airway pressures were observed with V-E technique. Failure rate of BMV was significantly higher with E-C technique (19%) as compared to V-E technique (1%) (P = 0.001). Conclusion: Two-handed V-E technique results in more effective ventilation as compared to two-handed E-C technique in patients with predictors of difficult BMV. This technique may be preferred as a first option in patients with anticipated DMV.

The impact of increased daily peanut consumption on indices of peripheral and cerebral vascular function in non-Hispanic Black individuals

Cardiovascular disease, neurocognitive conditions, and cerebral vascular diseases including cognitive impairment, stroke, and Alzheimer’s disease and related dementias disproportionately impact the Non-Hispanic Black (BL) population. The mechanisms are multifactorial but is related to reduced vascular function/health. Our lab, and others, have demonstrated that reduced nitric oxide (NO) bioavailability secondary to oxidative stress, systemic inflammation, and reduced L-arginine bioavailability contributes to reduced vascular function/health in this population. Increased dietary peanut consumption improves various physiological outcomes including blood pressure, cholesterol, type II diabetes, cognitive health, NO bioavailability, and vascular function/health. This improvement is related to increased bioavailability of L-arginine, reduced systemic inflammation, and antioxidant capacity. This study hypothesized that increased daily peanut consumption would improve indices of peripheral and cerebral vascular function/health in a cohort of BL individuals. Methods: Seventeen people participated (11 non-Hispanic White (WH) and 6 BL (age: WH 25±8, BL 21±2; BMI: WH 23±3, BL 22 ± 4; p&gt;0.05 for both). Measures were made before (pre) and after (post) 56 days of daily lightly salted peanut consumption (2 oz/day for females and 3 oz/day for males). Peripheral macro and microvascular function/health was assessed as brachial artery vasodilation (flow mediated dilation, %FMD) and forearm reactive hyperemia (peak mean forearm blood velocity (FBVmean) respectively following 5-min of suprasystolic cuff inflation. Cerebral vascular function/health was assessed as the cerebral vasodilator response during a hypercapnic challenge, i.e., the slope of % cerebral vascular conductance index (CVCi) relative to the change in end-tidal carbon dioxide concentration (ΔPETCO2). Results: There was no effect of race on peripheral macrovascular function assessed as %FMD (WH: 5.3 ±0.89, BL: 6.3 ±1.9 %, p=0.31) or peripheral microvascular function assessed as FBVmean (WH: 82.90 ± 4.5, BL: 72 ± 6.7 cm·s−1, p=0.13). Likewise, there no effect of treatment on %FMD (Pre: 5.4 ± 0.7, Post: 6.2 ± 2.1 %, p=0.46) or FBVmean (Pre: 81.4 ± 6.7, Post: 73.4 ± 8.8 cm·s−1, p=0.27). Lastly, there were no effect of race (WH: 4.0 ± 0.36, BL: 3.9 ± 0.6 %, p=0.85) or treatment (Pre: 3.9 ± 0.56, Post: 4.0 ± 0.39 %, p=0.79) on cerebral vascular function assessed as %CVCi during hypercapnia. Conclusion: The preliminary data suggest that 56 days of increased daily peanut consumption does not induce measurable improvements in indices of vascular function in a cohort of relatively young BL individuals. Future work will continue to assess this effect in a larger cohort of individuals as well as in individuals with existing conditions or diseases (i.e., hypertension, type II diabetes, etc.). Funding: Peanut Institute (982307). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Indices of cerebral vascular function &amp; health in young healthy adults: impact of sex and race

Background: Cerebral vascular diseases and neurocognitive conditions including stroke, cognitive impairment, &amp; Alzheimer’s disease and related dementias are the fastest growing causes of morbidity and mortality. Studies have demonstrated sex differences in indices of physiological function associated with cardiovascular and metabolic disease risk/prevalence. Further, the incidence of these conditions is elevated in Black (BL) individuals; however, BL females have a reduced age adjusted stroke mortality compared to BL males. Reduced cerebral vascular function/health contributes to the risk for these conditions. Limited studies have examined the influence of sex and race on indices of cerebral vascular function/health. This study examined the potential interaction between race and sex in cerebral pulsatility index (PI: index of cerebral vascular stiffness) and cerebral vasomotor reactivity (CVMR) to a hypercapnic challenge (index of cerebral vasodilatory responsiveness). Hypothesis: We hypothesized: 1) females would have reduced PI and elevated CVMR relative to males. 2) BL individuals would exhibit augmented PI and reduced CVMR. 3) BL females would have reduced PI relative to BL males. 4) Lastly, we posit that CVMR will be negatively correlated with PI. Methods: Data is presented from 136 young healthy individuals. 40 BL males (age: 22±3 yr, BMI: 25±4 kg/m²), 37 BL females (age: 21±3 yr, BMI: 24±4 kg/m²), 39 White (WH) males (age: 24±3 yr, BMI: 25±3 kg/m²), and 20 WH females (age: 25±6 yr, BMI: 23±3 kg/m²). Heart rate, beat-to-beat blood pressure, end-tidal carbon dioxide concentration (PETCO2), and middle cerebral artery blood velocity (MCAv) were continuously recorded (minimum of 6 min). Cerebral vascular function/health was indexed as (a) PI ((MCAVv systolic − MCAv diastolic)/MCAv mean). (b) CVMR assessed as % increase in cerebral vascular conductance (CVCi) slope during a hypercapnic challenge (%CVCi/ΔPETCO2). Results: PI was elevated in males (male: 0.86±0.18, female: 0.77±0.11, P=0.03). There was no difference between races (WH: 0.83±0.19, BL: 0.79±0.13, P=0.27) nor was there a sex x race interaction ( P=0.54). CVMR assessed as %CVCi slope was not different between sexes (male: 2.4±1.7 %/mmHg, female: 2.7±1.2 %/mmHg, P=0.16) or BL &amp; WH (WH: 2.7±1.3 %/mmHg, BL: 2.4±1.1 %/mmHg, P=0.16). CVMR was lower in the BL males relative to the BL females (BL male: 2.0±0.9 %/mmHg, BL female: 2.8±1.2 %/mmHg, P=0.002). There was no difference between WH males and females ( P=0.88). Lastly, there was not a significant correlation between PI and CVMR to hypercapnia ( P=0.16). Conclusion: These preliminary data suggest that relatively young and otherwise health White and Black females have augmented indices of cerebral vascular function/health relative to males. Furthermore, BL males have reduced cerebral vasodilatory responsiveness to a hypercapnic stimuli. The University of Texas at Arlington College of Nursing and Health Innovation and Institutional Start up Funds to Dr. Brothers. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Prehospital Surgical Cricothyrotomy in a Ground-Based 9-1-1 EMS System: A Retrospective Review.

Airway management is a cornerstone in the prehospital care of critically ill or injured patients. Surgical cricothyrotomy offers a rapid and effective solution when oxygenation and ventilation fail using less-invasive techniques. However, the exact indications, incidence, and success of prehospital surgical cricothyrotomy are unknown, with variable rates reported in the literature. This study aimed to examine prehospital indications and success rates for surgical cricothyrotomy within a large, suburban, ground-based Emergency Medical Services (EMS) system. This is a retrospective analysis of 31 patients who underwent paramedic performed surgical cricothyrotomy from 2012 through 2022. Key demographic parameters were analyzed, including the incidence of cardiac arrest, call type (trauma versus medical), initial airway management attempts, number of endotracheal intubation (ETI) attempts before surgical airway, and average time to the establishment of a surgical airway in relation to the number of ETI attempts. Surgical cricothyrotomy success was defined as the acquisition of four-phase end-tidal capnography reading. The primary data sources were the EMS electronic medical records, and descriptive statistics were calculated. A total of 31 patients were included in the final analysis. Of those who received a surgical cricothyrotomy, 42% (13/31) occurred in the trauma setting, while 58% (18/31) were medical calls. In all patients who underwent surgical cricothyrotomy, the median (IQR) time to the procedure was 17 minutes (IQR = 11-24). In trauma patients, the median time to surgical cricothyrotomy was 12 minutes (IQR = 9-19) versus 19 minutes (IQR = 14-33) in medical patients. End-tidal carbon dioxide (ETCO2) detection and placement success was confirmed in 94% (29/31) of patients. Endotracheal intubation was attempted in 55% (17/31) before subsequent surgical cricothyrotomy, with 29% (9/31) receiving more than one ETI attempt. The median time to surgical cricothyrotomy when multiple prior intubation attempts occurred was 33 minutes (IQR = 23-36) compared to 14.5 minutes (IQR = 6-19) in patients without a preceding intubation attempt. Prehospital surgical airway can be performed by paramedics with a high degree of success. Identification of the need for surgical cricothyrotomy should be determined as soon as possible to allow for rapid securement of the airway and to ensure adequate oxygenation and ventilation.

Practical method in the diagnosis of diabetic ketoacidosis: end-tidal carbon dioxide

Objectives: Diabetic ketoacidosis (DKA) poses a life-threatening risk in uncontrolled diabetes. Current diagnostic criteria rely on invasive measures, leading to potential delays in treatment initiation. This study aimed to assess the diagnostic utility of noninvasive end-tidal carbon dioxide (EtCO2) measurements in DKA patients. Methods: A prospective, cross-sectional study was conducted in a tertiary-level Emergency Medicine Clinic from January 2021 to January 2023. Participants included adults with DKA symptoms and those with stable vital signs as controls. EtCO2 levels were measured using a capnograph device. Diagnostic criteria for DKA were blood glucose ≥250 mg/dL, ketonuria, ketonemia, and metabolic acidosis (pH&amp;lt;7.3 or bicarbonate &amp;lt;15 mEq/dL). Statistical analysis was performed using SPSS Statistics. Results: Of 730 participants, 120 had DKA, 410 did not, and 200 served as controls. EtCO2 levels significantly differed between DKA, non-DKA, and control groups (P&amp;lt;0.05). EtCO2 correlated with pH, lactate, base deficit, and bicarbonate (P&amp;lt;0.05). ROC analysis showed an AUC of 0.86 for EtCO2 in diagnosing DKA (P&amp;lt;0.01), with 91.67% sensitivity and 74.39% specificity at a cut-off value 23.7. Conclusion: This study suggests that EtCO2 measurement is a valuable noninvasive tool for diagnosing and assessing the severity of DKA in the emergency department. An EtCO2 threshold of &amp;lt;23.7 could prompt consideration of DKA in patients with elevated blood glucose levels. More extensive multicenter studies are warranted to validate these findings further. EtCO2 measurement could facilitate early DKA diagnosis and improve patient outcomes.

Successful management of pulmonary edema secondary to accidental electrocution in a young dog

BackgroundHuman records describe pulmonary edema as a life-threatening complication of electric shock. Successful management requires prompt recognition and intensive care. However, in companion animals, electrocutions are rarely reported, even though domestic environments are full of electrical devices and there is always the possibility of accidental injury. Therefore, it is important for veterinarians to know more about this condition in order to achieve successful patient outcomes.Case presentationA 3-month-old male Labrador Retriever was presented with a history of transient loss of consciousness after chewing on a household electrical cord. On admission, the puppy showed an orthopneic position with moderate respiratory distress. Supplemental oxygen via nasal catheter was provided, but the patient showed marked worsening of respiratory status. Point-of-care ultrasound exams suggested neurogenic pulmonary edema due to electrical shock close to the central nervous system and increased B-lines without evidence of cardiac abnormalities. Mechanical ventilation of the patient was initiated using volume-controlled mode with a tidal volume of 9 to 15 ml/kg until reaching an end-tidal carbon dioxide ≤ 40 mm Hg, followed by a stepwise lung-recruitment maneuver in pressure-controlled mode with increases of the peak inspiratory pressure (15 to 20 cm H2O) and positive end-expiratory pressure (3 to 10 cm H2O) for 30 min, and return to volume-controlled mode with a tidal volume of 15 ml/kg until reaching a peripheral oxygen saturation ≥ 96%. Weaning from the ventilator was achieved in six hours, and the patient was discharged two days after admission without neurological or respiratory deficits.ConclusionsWe present a rather unusual case of a neurogenic pulmonary edema subsequent to accidental electrocution in a dog. Timely diagnosis by ultrasound and mechanical ventilation settings are described. Our case highlights that pulmonary edema should be considered a potentially life-threatening complication of electrical shock in small animal emergency and critical care medicine.

End-Tidal Carbon Dioxide Monitoring in Anesthesia: Unraveling the Mysteries of Respiratory and Circulatory Physiology

The present article underscored the indispensable significance of end-tidal carbon dioxide (ETCO2) monitoring in anesthesia and critical care, offering critical insights into both ventilation and metabolism dynamics. The meticulous management of tidal volume, respiratory rate, and inspired oxygen levels during anesthesia plays a pivotal role in maintaining optimal arterial oxygen and carbon dioxide concentrations. Effective ventilation is imperative for proper gas exchange within the alveoli and maintaining a stable acid-base balance. In the context of circulatory physiology during anesthesia, cardiac output, blood pressure, and tissue perfusion hold paramount importance. The present article highlights how anesthesia-induced alterations in vascular tone and cardiac function could influence circulation and tissue oxygenation, impacting parameters like blood pressure, heart rate, and ETCO2. Monitoring these parameters provides essential data for assessing circulatory status, guiding anesthesia management, and averting complications. ETCO2 monitoring has evolved into a standard practice in anesthesia and critical care settings, offering real-time, non-invasive insights. The present article delved into the extensive clinical applications, challenges, and future directions of ETCO2 monitoring. Encompassing fundamental principles, technological nuances, clinical implications, limitations, and avenues for research, this article advanced the understanding of this monitoring technique and its positive impact on patient care. The present article also discussed how ETCO2 levels reflect alveolar ventilation, providing critical data for assessing ventilation adequacy, readiness for extubation, and identification of impending respiratory distress. Furthermore, it delved into how ETCO2 levels serve as an indicator of cardiac output and tissue perfusion, guiding management strategies in various shock states and offering prognostic insights during CPR. Challenges and limitations associated with ETCO2 monitoring were clarified, with emphasis on technical considerations, patient populations with specific challenges, and potential interpretation pitfalls. The article outlines the exciting future directions of ETCO2 monitoring, encompassing wearable technology, remote monitoring capabilities, artificial intelligence integration, and potential applications beyond traditional realms. Keywords: Anesthesia; Capnography; Critical care; End-tidal carbon dioxide; ETCO2 monitoring

Influence of Head and Neck Position on Ventilation Using Three Different Supraglottic Airway Devices (I-Gel, Ambu Auragain, BaskaMask) in Anaesthetized and Paralyzed Patients: A Prospective Randomized Clinical Study

Background: Supraglottic airway devices play a crucial role in managing the airway during various surgical procedures conducted under general anesthesia. In this study, we evaluated the impact of different head and neck positions (extension, flexion, neutral, and right rotation) on ventilation while using I-gel, Ambu AuraGain, and Baska masks in anesthetized paralyzed patients. Methodology: A total of 114 patients were randomly allocated into Group I (n=38) using I-Gel, Group II (n=38) using Ambu AuraGain, and Group III (n=38) using Baska Mask. Clinical performance in terms of OLP (Oropharyngeal Leak Pressure) and anatomical position of the device was evaluated after insertion under general anaesthesia. Ventilation parameters including peak airway pressure, EtCO2 (End-tidal Carbon Dioxide), expiratory tidal volume and ventilation score were assessed at different head and neck positions using three supraglottic airway devices. Results : Maximum OLP was observed in Group II and minimum OLP was observed in Group I. In all three devices, OLP was maximum in the flexion position and minimum in the extension position. The Median Brimacombe score was 3 in all three groups at all head and neck positions except at maximum extension in Group I. Although peak airway pressure in Group II is significantly higher than the other two groups, ventilation is not impacted as evidenced by comparable ventilation score, EtCO2 and expiratory tidal volume in all patients of three groups at different head and neck positions. Conclusion : To conclude, Ambu Auragain has better anatomical seal at all head and neck positions as compared to I-gel and Baska Mask. However, despite differences in OLP, the ventilatory performances of the three devices were not significantly affected. Keywords: Ambu Auragain, Baska Mask, I-Gel, Supraglottic Airway Device, Head And Neck Position, Oropharyngeal Leak Pressure

The effect of hypertension on cerebrovascular carbon dioxide reactivity in atrial fibrillation patients

Atrial fibrillation (AF) and hypertension (HTN) are both associated with impaired cerebrovascular carbon dioxide reactivity (CVRCO2), an indicator of cerebral vasodilatory reserve. We hypothesised that CVRCO2 would be lower in patients with both AF and HTN (AF + HTN) compared to normotensive AF patients, due to an additive effect of AF and HTN on CVRCO2. Forty AF (68 ± 9 years) and fifty-seven AF + HTN (68 ± 8 years) patients underwent transcranial Doppler ultrasound measurement of middle cerebral artery blood velocity (MCA Vm) during stepped increases and decreases in end-tidal carbon dioxide (PETCO2). A cerebrovascular conductance index (CVCi) was calculated as the ratio of MCA Vm and mean arterial pressure (MAP). CVRCO2 was determined from the linear slope for MCA Vm and MCA CVCi vs PETCO2. Baseline MAP was higher in AF + HTN than AF (107 ± 9 vs. 98 ± 9 mmHg, respectively; p < 0.001), while MCA Vm was not different (AF + HTN:49.6 [44.1–69.0]; AF:51.7 [45.2–63.3] cm.s−1; p = 0.075), and CVCi was lower in AF + HTN (0.46 [0.42–0.57] vs. 0.54 [0.44–0.63] cm.s−1.mmHg−1; p < 0.001). MCA Vm CVRCO2 was not different (AF + HTN: 1.70 [1.47–2.19]; AF 1.74 [1.54–2.52] cm/s/mmHg−2; p = 0.221), while CVCi CVRCO2 was 13% lower in AF + HTN (0.013 ± 0.004 vs 0.015 ± 0.005 cm.s−1.mmHg−1; p = 0.047). Our results demonstrate blunted cerebral vasodilatory reserve (determined as MCA CVCi CVRCO2) in AF + HTN compared to AF alone. This may implicate HTN as a driver of further cerebrovascular dysfunction in AF that may be important for the development of AF-related cerebrovascular events and downstream cognitive decline.We demonstrated reduced cerebrovascular CO2 responsiveness in atrial fibrillation with hypertension (AF+HTN) vs. atrial fibrillation (AF). Furthermore, AF per se (as opposed to normal sinus rhythm) predicts reduced cerebrovascular CO2 responsiveness. Our findings suggest additional cerebrovascular dysfunction in AF+HTN vs. AF.

Anesthesia experience in an adult Silver-Russell syndrome: a case report

BackgroundThere are no reports of anesthesia use in adult patients with Silver-Russell syndrome (SRS). Here, we report our experience with anesthesia in an adult patient with SRS complicated by chronic respiratory failure.Case presentationA 33-year-old woman was clinically diagnosed with SRS. She had severe chronic respiratory failure, complicated by superior mesenteric artery syndrome. Percutaneous gastrostomy was scheduled for nutritional management under epidural anesthesia; however, soon after esophagogastroduodenoscopy was started, she lost consciousness and spontaneous respiration. The patient was urgently intubated and converted to general anesthesia. The end-tidal carbon dioxide tension was > 90 mmHg at intubation.ConclusionsAdult SRS patients with chronic respiratory failure have a risk of CO2 narcosis. SRS also requires preparation for difficult airway management during the perioperative period.

Immediate effect of physical activity on the autonomic nervous system in individuals with autism spectrum disorders of different age groups: a randomised trial

BackgroundAutism spectrum disorder (ASD) is one of the most complex neurodevelopmental disorders. It affects almost all human physiological systems. Individuals with ASD often display dysregulation in their autonomic nervous system...