PETCO2 Values Research Articles

Persisting exercise ventilatory inefficiency in subjects recovering from COVID-19. Longitudinal data analysis 34 months post-discharge

BackgroundSARS-CoV-2 infection has raised concerns about long-term health repercussions. Exercise ventilatory inefficiency (EVin) has emerged as a notable long-term sequela, potentially impacting respiratory and cardiovascular health. This study aims to assess the long-term presence of EVin after 34 months and its association with cardiorespiratory health in post-COVID patients.MethodsIn a longitudinal study on 32 selected post-COVID subjects, we performed two cardiopulmonary exercise tests (CPETs) at 6 months (T0) and 34 months (T1) after hospital discharge. The study sought to explore the long-term persistence of EVin and its correlation with respiratory and cardiovascular responses during exercise. Measurements included also V̇O2peak, end-tidal pressure of CO2 (PETCO2) levels, oxygen uptake efficiency slope (OUES) and other cardiorespiratory parameters, with statistical significance set at p < 0.05. The presence of EVin at both T0 and T1 defines a persisting EVin (pEVin).ResultsOut of the cohort, five subjects (16%) have pEVin at 34 months. Subjects with pEVin, compared to those with ventilatory efficiency (Evef) have lower values of PETCO2 throughout exercise, showing hyperventilation. Evef subjects demonstrated selective improvements in DLCO and oxygen pulse, suggesting a recovery in cardiorespiratory function over time. In contrast, those with pEvin did not exhibit these improvements. Notably, significant correlations were found between hyperventilation (measured by PETCO2), oxygen pulse and OUES, indicating the potential prognostic value of OUES and Evin in post-COVID follow-ups.ConclusionsThe study highlights the clinical importance of long-term follow-up for post-COVID patients, as a significant group exhibit persistent EVin, which correlates with altered and potentially unfavorable cardiovascular responses to exercise. These findings advocate for the continued investigation into the long-term health impacts of COVID-19, especially regarding persistent ventilatory inefficiencies and their implications on patient health outcomes.

Effect of target-controlled infusion of remifentanil in combination with propofol on anesthesia and endotracheal intubation response in patients undergoing surgical aneurysm clipping

Purpose: To investigate the effect of target-controlled infusion of remifentanil in combination with propofol on anesthesia and endotracheal intubation response in patients undergoing surgical aneurysm clipping. &#x0D; Methods: The clinical data of 106 patients undergoing surgical aneurysm clipping at the Central Hospital of Wuhan, Wuhan City, China from September 2020 to December 2022 were retrospectively analyzed. Subjects in control group were given fentanyl intravenous infusion anesthesia while study group was treated with target-controlled infusion anesthesia of remifentanil combined with propofol. Hemodynamics and blood-gas indices were evaluated before anesthesia (T1), immediately after endotracheal intubation (T2) and at extubation (T3). The incidence of anesthesia-related complications was determined. &#x0D; Results: In study group, the agitation score was decreased compared to that of control group, while the Ramsay sedation score was increased (p &lt; 0.05). The incidence of cough during endotracheal catheter indwelling and extubation was 7. 27 % in study group, which was less than 21. 57 % in control group (p &lt; 0.05). The cough score of study group was also reduced (p &lt; 0.05). There were no significant differences in the SpO2 and PetCO2 values between the two groups at different times (p &gt; 0.05). Furthermore, the mean arterial pressure at T2 and T3 was upregulated and heart rate (HR) was downregulated in study group (p &lt; 0.05). Recovery time of spontaneous respiration, time of eye-opening and extubation in study group were decreased compared to control group (p &lt; 0.05). &#x0D; Conclusion: Target-controlled infusion of remifentanil in combination with propofol improves anesthetic effect in patients undergoing surgical aneurysm clipping, reduces tracheal intubation reaction, maintains hemodynamic stability and improves recovery quality of patients. Future study will be required to evaluate the efficacy and optimal effective concentration in a diverse population.

Comparison of low and standard pneumoperitoneum pressure in laparoscopic pediatric inguinal hernia repair.

The effectiveness and safety of low pneumoperitoneum in laparoscopic pediatric inguinal hernia repair is unclear and required to explore. To evaluate the benefits of low (LPP) vs. standard pneumoperitoneum pressure (SPP) in laparoscopic pediatric inguinal hernia repair. We performed a retrospective cohort analysis of patients with pediatric inguinal hernia. The patients were divided into LPP and SPP groups. Anesthesia and postoperative characteristics were analyzed. We enrolled 169 eligible patients in this study. Anesthesia and postanesthesia care unit times in the LPP group were lower than those in the SPP group (p = 0.00, p = 0.01, respectively). The LPP group had lower values for peak partial pressure of end-tidal carbon dioxide (PETCO2; mm Hg) (33.37 ±4.09 vs. 36.56 ±4.08), trough PETCO2 (38.33 ±5.04 vs. 40.46 ±4.14), and PETCO2 at the end of surgery (35.29 ±4.59 vs. 38.76 ±4.22). The LPP group required less sufentanil citrate (8.76 ±4.07 ml vs. 18.03 ±16.04 ml) and midazolam (1.56 ±0.45 ml vs 1.79 ±0.59 ml) vs. the SPP group, respectively. There was no significant difference between the groups regarding postoperative complications. LPP was associated with shorter anesthesia and postanesthesia care unit times, and lower PETCO2 values compared with SPP. Compared with the SPP group, the LPP group had comparable operation times and postoperative complications. However, long-term outcome studies are needed.

The effects of subconcussive head impacts on cerebral vascular reactivity

Purpose: One bout of repetitive subconcussive head impacts (SHI) can increase biomarkers of neurological injury, decrease neurovascular coupling, and alter cerebral autoregulation. It is unclear whether a bout of repetitive SHI alters cerebral vascular reactivity to carbon dioxide (CVR). We tested the hypotheses that CVR to hypercapnia (CVRhyper) and hypocapnia (CVRhypo) will decrease after a bout of repetitive SHI in healthy participants. Methods: Eight healthy participants (age: 20±2 y; BMI: 23±3 kg/m2; 2 women) completed four CVR tests: one prior to a bout of SHI (PRE), and three follow-up tests at 2 h, 24 h, and 72 h after the SHI. SHI were induced by 20 soccer headers projected from a soccer JUGS machine (1 header/30 s at 40 km/h and from 12.2 m). Mean arterial pressure (MAP), heart rate (HR), end tidal carbon dioxide tension (PETCO2), middle cerebral artery blood velocity (MCAV) and posterior cerebral artery blood velocity (PCAV) were measured prior to and during each CVR test. MCA conductance (MCAcon) and PCA conductance (PCAcon) were calculated as the quotient of MCAv and PCAv to MAP, respectively. During the CVRhyper test, participants inhaled 6% CO2, 21% O2, 73% N2 gas for 2 min or until PETCO2 was 10 mmHg greater than baseline. 3 min after the CVRhyper test, participants hyperventilated until PETCO2 was 10 mmHg less than baseline for 2 min (CVRhypo). PETCO2 values were plotted against MCAV, PCAV, MCAcon, and PCAcon at baseline and the last 10 s of each CVR test. The slopes of these linear regression lines were calculated for each variable and for both CVR tests. Data are presented as mean±SD. Results: There were no differences from PRE to post SHI for resting HR, PETCO2, MCAV, PCAV, MCAcon, or PCAcon (all p&gt;0.13). A time effect was found for resting MAP (PRE: 90±10; 2 h: 101±8; 24 h: 86±4; 72 h: 88±10 mmHg; p=0.02). There were no differences from PRE to post SHI for the CVRhyper test for MCAV (PRE: 0.10±0.20; 2 h: 0.27±0.17; 24 h: 0.24±0.31; 72 h: 0.24±0.31 cm/s/mmHg; p=0.13), MCAcon (PRE: -0.0009±0.0014; 2 h: -0.0001±0.0023; 24 h: -0.0002±0.0017; 72 h: -0.0011±0.0017 cm/s/mmHg/mmHg; p=0.36), PCAV (PRE: 0.02±0.13; 2 h: 0.07±0.07; 24 h: 0.12±0.18; 72 h: 0.14±0.13 cm/s/mmHg; p=0.26), or PCAcon (PRE: 0.0018±0.0011; 2 h: 0.0014±0.0007; 24 h: 0.0033±0.0033; 72 h: 0.0012±0.0007 cm/s/mmHg/mmHg; p=0.18). There were also no differences from PRE to post SHI for the CVRhypo test for MCAV (PRE: 0.10±0.20; 2 h: 0.27±0.17; 24 h: 0.24±0.31; 72 h: 0.24±0.31 cm/s/mmHg; p=0.13), MCAcon (PRE: 0.0006±0.0019; 2 h: 0.0019±0.0011; 24 h: 0.004±0.0049; 72 h: 0.0025±0.0016 cm/s/mmHg/mmHg; p=0.10), PCAV (PRE: 0.02±0.13; 2 h: 0.07±0.07; 24 h: 0.12±0.18; 72 h: 0.14±0.13 cm/s/mmHg; p=0.26), or PCAcon (PRE: 0.0018±0.0016; 2 h: 0.0019±0.0007; 24 h: 0.004±0.0033; 72 h: 0.0037±0.0014; p=0.09). Conclusion: These preliminary data indicate that a bout of soccer headings does not change CVR to carbon dioxide in the MCA or PCA in healthy adults. This is the full abstract presented at the American Physiology Summit 2023 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.

Effect of transcutaneous acupoint electrical stimulation at Neiguan (PC 6) on general anesthesia under preserving spontaneous breathing in thoracoscopic lobectomy

To evaluate the effect of transcutaneous acupoint electrical stimulation (TEAS) at Neiguan (PC 6) on general anesthesia under preserving spontaneous breathing in thoracoscopic lobectomy. A total of 66 patients of primary lung cancer undergoing thoracoscopic lobectomy were divided to an observation group (33 cases, 1 case discontinued) and a control group (33 cases). In the observation group, TEAS at Neiguan (PC 6) was used 30 min before anesthesia induction till the end of surgery. The surgery time, maximum value of partial pressure of end-tidal carbon dioxide (PETCO2) and minimum value of oxygen saturation (SpO2) of the two groups were recorded. The dosage of propofol, sufentanil, remifentanil and dexmedetomidine were analyzed. Separately, before induction (T0), at the start of surgery (T1), thoracic exploration (T2) and lobectomy (T3), as well as 30 min (T4) and 60 min (T5) after lobectomy, the mean arterial pressure (MAP), heart rate (HR), respiratory rate (RR), serum cortisol (Cor) and norepinephrine (NE) were measured. The time of post anesthesia care unit (PACU) stay, ambulation, flatus, chest drainage and the incidence of nausea and vomiting were compared between the two groups. The maximum value of PETCO2, the dosage of propofol and remifentanil in the observation group were lower than those in the control group (P < 0.05, P < 0.01), the minimum value of SpO2 in the observation group was higher than that of the control group (P < 0.01). At T1-T5, the MAP, HR, serum Cor and NE levels in the observation group were all lower than those in the control group (P < 0.05). The ambulation time, the time for the flatus, chest drainage time, and the incidence of nausea and vomiting in the observation group were all lower than those in the control group (P<0.001, P < 0.01). For the general anesthesia under preserving spontaneous breathing in thoracoscopic surgery, TEAS at Neiguan (PC 6) relieves stress response, reduces opioids dosage and promotes postoperative recovery.

Characteristics of cardiopulmonary exercise test in tracheobronchial tuberculosis patients with central airway stenosis

BackgroundA typical symptom of central airway stenosis is progressive dyspnea. The exercise capacity and relationship between pulmonary function testing (PFT) and central airway stenosis have not been reported. ObjectivesTo investigate, for the first time, the impact of central airway stenosis due to tracheobronchial tuberculosis (TBTB) on exercise capacity in adults. MethodsFifty-one patients diagnosed with TBTB and 51 healthy, non-smoking adults (controls) were studied. All participants underwent a maximal cardiopulmonary exercise test (CPET) after completing PFT. ResultsAll participants completed the PFT and CPET. Significant differences existed between the two groups with respect to PFT parameters. At rest, no significant differences were detected between the two groups with respect to oxygen uptake (VO2), vital volume (VT), minute ventilation (VE), end-tidal carbon dioxide (PetCO2), and oxygen pulse (SPO2). Compared to controls, TBTB patients had lower peak work rate [WR, 100 (83,119) vs. 112 (95,146)], VO2 at maximal exercise (1309.51±323.83 vs. 1522.17±451.15), anaerobic threshold (905.8 ± 219.84 vs. 1024.72±296.27), maximal O2 pulse (8.02±1.61 vs. 9.26±2.36), and breath reserve [BR, 25 (15,42) vs. 49.5(39.4,61.3)]. The change in PetCO2 values at rest and maximal exercise was lower than in controls (P<0.05). However, no difference in VE/carbon dioxide production (VCO2)@AT were demonstrated between the two groups. The correlations between the degree of stenosis, PFT parameters, and VO2 peak were significant. RV/TLC%pred was a good predictor of exercise limitation in these patients. ConclusionThe maximal exercise capacity and PFT parameters of TBTB patients with central airway stenosis were impaired. Impaired exercise capacity correlated with the degree of central airway stenosis.

Validation Criteria for PETCO2 Kinetics during the Hyperventilation Provocation Test in the Diagnosis of Idiopathic Hyperventilation Syndrome.

Background: The hyperventilation provocation test (HPTest) is a diagnostic tool for idiopathic hyperventilation syndrome (HVS), encountered in some long-COVID patients. However, interpretation of the HPTest remains unclear regarding the relevant PETCO2 values to focus on and whether subjective symptoms should be considered. This study aimed to re-evaluate objective HPTest results for diagnosing HVS by determining accurate PETCO2 kinetics in two groups of patients previously screened via the Nijmegen questionnaire (NQ). Methods: The kinetics of PETCO2 during the HPTest were mathematically modeled and compared between 37 HVS patients (NQ ≥23/64) and 37 healthy controls (NQ <23/64) matched for gender, age, and body dimensions. AUC values with sensitivity and specificity were calculated, and analysis was monitored in a validation cohort of 152 routine HPTests. Results: A threshold value of a less than 12.8 mmHg increment of PETCO2 at the 5th minute of the recovery phase of the HPTest diagnosed HVS patients with excellent sensitivity (0.92) and specificity (0.84). These results were confirmed in the validation cohort, highlighting the presence of 24% false positives/negatives when diagnosing on the basis of complaints in the NQ. Conclusions: For HVS diagnosis, we suggest considering the HPTest, which can more reliably reflect the mechanisms of CO2 homeostasis and the response of the respiratory center to a stimulus, regardless of the subjective onset of symptoms.

Early aortic valve replacement improves exercise capacity in truly asymptomatic patients with severe aortic stenosis

Abstract Background Exercise capacity is a strong predictor of morbidity and mortality overall. In severe aortic stenosis (AS) ustained pressure overload during watchful waiting is associated with LV structural and functional deterioration and impaired clinical outcome both pre- and post aortic valve replacement (AVR). The effect of early surgical aortic valve replacement (SAVR) in asymptomatic patients with severe AS and normal left ventricular function on exercise capacity in unknown. Aim We investigated whether the early surgical AVR in truly asymptomatic patients with severe aortic stenosis and normal LVEF improves the exercise capacity. Methods This is a sub-analysis or the AVATAR trial (NCT02436655), which is international prospective randomized controlled trial that evaluated the safety and efficacy of early SAVR in the treatment of asymptomatic patients with severe AS, according to common criteria (valve area ≤1 cm2 with aortic jet velocity &amp;gt;4 m/s or a mean transaortic gradient ≥40 mm Hg), and with normal left ventricular function. Patients underwent cardiopulmonary exercise testing (supine bicycle, ramp protocol, 15 W/min) at the baseline and 12 months following the randomization. Patients who had positive exercise testing at baseline visit were excluded. We compared the value of workload (in WATs), VO2 max, VO2 AT, VE/VCO2 and PETCO2 slope at the inclusion and at 12 months. Results Total of 157 patients (mean age, 67 years; 57% men) were randomly allocated to early surgery (n=78) or conservative treatment (n=79). Mean LVEF and Vmax in early surgery and conservative treatment group were 70% and 4.5m/s and 69% and 4.5m/s, respectively. After 12 months in patients with conservative treatment there was a slight decrease in the values of workload, VO2 max, VO2 AT, VE/VCO2 and PETCO2 slope, but without statistical significance. However operated patients showed a significant increase in workload (115.4±38.4 watts at 12 months vs 104.8±42.2 at inclusion, p=0.038) and VO2 max (19.7±6.8 at 12 months vs 16.2±5.4 at the inclusion, p=0.048), while there was slight increase in the values of VO2 AT, VEVCO2 and PETCO2 but without statistical significance. Conclusion Early SAVR improve the functional capacity in asymptomatic patients with severe aortic stenosis and normal left ventricular ejection fraction Funding Acknowledgement Type of funding sources: None.

Variation of PetCO2 during incremental exercise and severity of IPAH and CTEPH

Background and objectiveEnd-tidal PCO2 (PetCO2) patterns during exercise testing as well as ventilatory equivalents for CO2 have been reported for different pulmonary vascular diseases but seldomly for the significant differences in exercise response depending on the etiology of pulmonary hypertension. We aimed to compare PetCO2 change pattern in IPAH and CTEPH with varying severity during incremental cardiopulmonary exercise testing (CPET).Methods164 IPAH patients and 135 CTEPH patients referred to Shanghai Pulmonary Hospital between 2012 and 2019 were retrospectively recruited into the study. All patients performed CPET and also underwent right-heart catheterization (RHC). Forty-four healthy subjects also performed CPET and were included as controls.ResultsPetCO2 was significantly lower in IPAH and CTEPH patients as compared to normal subjects. Moreover, the PetCO2 did not rise, in fact fell from rest to anaerobic threshold (AT), then further decreased until peak in both IPAH and CTEPH. PetCO2 value at rest, unloaded, AT and peak were proportionately reduced as the World Health Organization functional class (WHO-Fc) increased in both IPAH and CTEPH patients. The PETCO2 in IPAH patients had significant differences during all phases of exercise between WHO-Fc I-II and III-IV subgroup. CTEPH also demonstrated significant difference except for PetCO2 at peak. PetCO2 values were significantly higher in IPAH during all phases of exercise as compared to CTEPH patients (all P < 0.001).PeakVO2%pred correlated significantly with PetCO2 at rest (r = 0.477, P < 0.001), AT (r = 0.609, P < 0.001) and peak exercise (r = 0.576, P < 0.001) in IPAH. N-terminal natriuretic peptide type-B (NT-proBNP) also correlated markedly with PetCO2, with a correlation coefficient of − 0.326 to − 0.427 (all P < 0.001). Additionally, PetCO2 at rest, at AT and at peak correlated positively with peakVO2%pred and showed an inverse correlation with NT-proBNP in CTEPH patients (all P < 0.05).ConclusionsPetCO2 during exercise in IPAH and CTEPH patients was significantly different from normal subjects. Moreover, PetCO2 values were significantly higher in IPAH during all phases of exercise as compared to CTEPH patients (all P < 0.001). PetCO2 was progressively more abnormal with increasing disease severity according to peakVO2%pred and WHO-Fc.

Profound hypercapnia but only moderate hypoxia found during underwater rugby play

Background: Underwater rugby is a team sport where players try to score points with a negatively buoyant ball while submerged in a swimming pool. Reports of syncope incidents at the Swedish Championships led to us to investigate end-tidal oxygen and carbon dioxide levels during simulated match play. Methods: Eight male underwater rugby club players of varying experience participated. Repetitive measurements were made while players were defending during simulated match play. Each time a player surfaced they exhaled through a mouthpiece connected to a flow meter and a gas analyzer to measure tidal volume, PETO2 and PETCO2. Results: Measurements were made over 12 dives, with an average dive duration of 18.5 seconds. The mean maximal PETCO2 across the eight participants was 10.0 kPa (~75 mmHg) (range, 9.1–11.7 [~68–88]). The corresponding mean minimum PETO2 was 7.6 kPa (~57 mmHg) (6.3–10.4 [~47–78)). PETCO2 drifted upward, with the mean upward change from the first to last dive for each participant being +1.8 (~13.5 mmHg) (SD 1.74) kPa. A similar trend for PETO2 was not detected, with a mean change of -0.1 (~0.75 mmHg) (SD 3.79) kPa. Conclusion: Despite high PETCO2 values that were close to narcotic being recorded, these players seemed to regulate their urge to breathe based on hypoxia rather than hypercapnia.

Cardiopulmonary Exercise Performance and Endothelial Function in Convalescent COVID-19 Patients.

Background: Endothelial dysfunction has been proposed as the common pathogenic background of most manifestations of coronavirus disease 2019 (COVID-19). Among these, some authors also reported an impaired exercise response during cardiopulmonary exercise testing (CPET). We aimed to explore the potential association between endothelial dysfunction and the reduced CPET performance in COVID-19 survivors. Methods: 36 consecutive COVID-19 survivors underwent symptom-limited incremental CPET and assessment of endothelium-dependent flow-mediate dilation (FMD) according to standardized protocols. Results: A significantly higher FMD was documented in patients with a preserved, as compared to those with a reduced, exercise capacity (4.11% ± 2.08 vs. 2.54% ± 1.85, p = 0.048), confirmed in a multivariate analysis (β = 0.899, p = 0.038). In the overall study population, FMD values showed a significant Pearson’s correlation with two primary CPET parameters, namely ventilation/carbon dioxide production (VE/VCO2) slope (r = −0.371, p = 0.026) and end-tidal carbon dioxide tension (PETCO2) at peak (r = 0.439, p = 0.007). In multiple linear regressions, FMD was the only independent predictor of VE/VCO2 slope (β = −1.308, p = 0.029) and peak PETCO2 values (β = 0.779, p = 0.021). Accordingly, when stratifying our study population based on their ventilatory efficiency, patients with a ventilatory class III-IV (VE/VCO2 slope ≥ 36) exhibited significantly lower FMD values as compared to those with a ventilatory class I-II. Conclusions: The alteration of endothelial barrier properties in systemic and pulmonary circulation may represent a key pathogenic mechanism of the reduced CPET performance in COVID-19 survivors. Personalized pharmacological and rehabilitation strategies targeting endothelial function may represent an attractive therapeutic option.

End-tidal carbon dioxide partial pressure to assess the value of passive leg-raising test in predicting volume responsiveness in patients with septic shock

To investigate the value of partial pressure of end-tidal carbon dioxide (PETCO2) combined with passive leg raising test (PLR) in predicting volume responsiveness in patients with septic shock. A total of 43 patients with septic shock admitted to the second department of critical care medicine, People's Hospital of Xinjiang Uygur Autonomous Region from December 2019 to June 2021 were selected as the research subjects. PETCO2, cardiac index (CI), stroke volume variation (SVV), mean arterial pressure (MAP) and other hemodynamic indexes were monitored before and after PLR and volume stress test (VE). Subjects were grouped according to the CI variation rate (ΔCI) after VE test. Patients with ΔCI ≥ 15% were the responding group, and patients with ΔCI < 15% were the non-responding group. The receiver operator characteristic curve (ROC curve) was drawn to analyze the evaluation value of the change in PETCO2 after PLR on the evaluation value of fluid responsiveness. Among the 43 patients, 22 cases were in the responding group, accounting for 51.2%; 21 cases were in the non-responding group, accounting for 48.8%. After the PLR test, the change values of MAP, SVV, CI and PETCO2 in the responding group were higher than those in the non-responding group, and the differences were statistically significant [MAP (mmHg): 3.8±2.1 vs. 1.4±2.0, SVV (%): -5.3±2.5 vs. 2.7±2.0, CI (mL×s-1×m-2): 0.48±0.13 vs. 0.14±0.18, PETCO2 (mmHg): 3.4±1.8 vs. 1.1±1.0, all P < 0.05, 1 mmHg ≈ 0.133 kPa]. After the VE test, the changes of HR, MAP, SVV, CI and PETCO2 in the responding group were higher than those in the non-responding group [HR (times/min): -8.3±2.8 vs. -2.3±3.7, MAP (mmHg): 3.8±2.4 vs. 1.2±1.7, SVV (%): -6.3±3.1 vs. -3.3±2.0, CI (mL×s-1×m-2): 0.51±0.14 vs. 0.16±0.12, PETCO2 (mmHg): 3.3±1.2 vs. 1.3±1.1, all P < 0.05]. The area under the ROC curve (AUC) of the change in PETCO2 before and after the PLR test (ΔPETCO2 PLR) for evaluating fluid responsiveness was 0.881. When the critical value was 5.9%, the sensitivity was 76.7%, the specificity was 89.5%, and the correct index was 0.68; the AUC for SVV baseline assessment of fluid responsiveness was 0.835, and when the cut-off value was 12.8%, the sensitivity was 84.6%, the specificity was 80.0%, and the correct index was 0.65. The predictive value of ΔPETCO2 was not lower than the SVV baseline. After the PLR test, the change of PETCO2 can be used as a non-invasive, simple, safe and reliable indicator for predicting the volume responsiveness of patients with septic shock.

The Evaluation of End Tidal Carbon Dioxide Values in Intubated Patients with COVID-19.

Background:The aim of this study is to establish the value of PETCO2 in COVID-19 patients intubated in emergency department, and its effects on mortality.Objectives:Between May 15, 2020 and January 15, 2021, The patients aged ≥18 years and diagnosed COVID-19, scheduled for urgent intubation in the emergency department were included.Method:Single-center, prospective and observational study. Age, gender, vital signs, laboratory findings are recorded. Immediately after intubation as measured by the capnography, the initial PETCO2_1 and at post-ventilation 15 min, PETCO2_2 and first, second arterial blood gas analysis are recorded.Results:The mean age of the 48 patients was 74 years. The PETCO2_1 and PETCO2_2 measurements were statistically significantly different between the patients who survived and those who died (p=0.014, p=0.015). The patients with a high first PETCO2_1 value and a decrease to the normal level survived, but those with a low PETCO2_1 value that could not increase to a normal value died (p=0.038, p=0.031). Increased levels of SpO2, PETCO2_1, PETCO2_2 and PaCO2_2 decreased the risk of mortality, while an increased level of PaO2_2 increased the risk of mortality.Conclusion:Capnography is non-invasive and provides continuous measurement. Assessment of changes in PETCO2 value would contribute to patient survival. (www.actabiomedica.it)

COMPARATIVE CHARACTERISTICS OF THE DYNAMICS OF CARDIOVASCULAR AND RESPIRATORY EFFECTS OF PNEUMOPERITONEUM BASED ON CARBON DIOXIDE AND ARGON IN LAPAROSCOPIC CHOLECYSTECTOMY

Pneumoperitoneum is one of the most critical components of laparoscopic surgery, which has a negative effect on gas exchange and stress to circulatory buffering system. One of the top priorities of laparoscopic technologies is to minimize the impact on the respiratory and cardiovascular systems, metabolic dynamics and compensatory abilities of homeostasis.&#x0D; The main goal of this research work is to compare the effects of carboxyperitoneum and argonoperitoneum on the intraoperative dynamics of CO2 concentration as well as cardiovascular and respiratory characteristics in patients undergoing laparoscopic cholecystectomy for various forms of cholelithiasis.&#x0D; Materials and methods. Four experimental groups involved patients based on their nosological form of cholelithiasis and the gas used to induce pneumoperitoneum. All patients underwent laparoscopic cholecystectomy by means of standard procedure. Either medical carbon dioxide or medical argon was used to induce pneumoperitoneum. Intraoperative monitoring of blood carbon dioxide levels PaCO2 was performed by taking venous blood every 15 minutes. Capnometry was performed by means of mainstream analysis using “BIOMED” BM1000C modular patient monitor by recording the discrete values of PetCO2 every 15 minutes, as well as by analyzing photocopies of capnography curves every 15 minutes.&#x0D; Intraoperative echocardiography was performed to identify the mean arterial pressure (MAP), heart rate (HR) and cardiac output (CO) in order to assess the effects of different types of pneumoperitoneum on the cardiovascular system.&#x0D; Results. The obtained data confirm the expected difference in the indices of cardiorespiratory functions between patients with acute cholecystitis and cholelithiasis without signs of inflammation. The investigation revealed that under the influence of pneumoperitoneum, heart rate and mean arterial pressure increase, while the cardiac output decreases. The respiratory pressure marker depends more on the intra-abdominal pressure and presumably the patient’s body type than on the presence of inflammatory syndrome. Argon insufflation has a slight negative impact on the cardiovascular system. Particularly, the mean arterial pressure and heart rate increase, while the cardiac output marker is less decreased as compared to the use of carbon dioxide. Abdominal pressure has a significant effect on the cardiovascular and respiratory systems regardless of the used type of gas. The combination of high intra-abdominal pressure with the elevated head end of the operating table, which is a common practise during cholecystectomy, has especially great influence on cardiovascular and respiratory functions. Operation which is carried out at decreased pressure allows reducing the deviations of practically all indices.&#x0D; Conclusions. Thus, the cardiovascular and respiratory systems adapt under the influence of pneumoperitoneum, providing compensation for the negative effects of mechanical and resorptive-metabolic character. Compensatory-adaptive abilities of the cardiovascular and respiratory systems increase with the decrease of intra-abdominal pressure. The use of argon as a working gas for insufflation into the abdominal cavity during laparoscopy reduces the negative impact of pneumoperitoneum on the cardiovascular and respiratory systems, providing a greater reserve of homeostatic and buffer systems of the body.

Respiration monitoring in PACU using ventilation and gas exchange parameters

The importance of perioperative respiration monitoring is highlighted by high incidences of postoperative respiratory complications unrelated to the original disease. The objectives of this pilot study were to (1) simultaneously acquire respiration rate (RR), tidal volume (TV), minute ventilation (MV), SpO2 and PetCO2 from patients in post-anesthesia care unit (PACU) and (2) identify a practical continuous respiration monitoring method by analyzing the acquired data in terms of their ability and reliability in assessing a patient’s respiratory status. Thirteen non-intubated patients completed this observational study. A portable electrical impedance tomography (EIT) device was used to acquire RREIT, TV and MV, while PetCO2, RRCap and SpO2 were measured by a Capnostream35. Hypoventilation and respiratory events, e.g., apnea and hypopnea, could be detected reliably using RREIT, TV and MV. PetCO2 and SpO2 provided the gas exchange information, but were unable to detect hypoventilation in a timely fashion. Although SpO2 was stable, the sidestream capnography using the oronasal cannula was often unstable and produced fluctuating PetCO2 values. The coefficient of determination (R2) value between RREIT and RRCap was 0.65 with a percentage error of 52.5%. Based on our results, we identified RR, TV, MV and SpO2 as a set of respiratory parameters for robust continuous respiration monitoring of non-intubated patients. Such a respiration monitor with both ventilation and gas exchange parameters would be reliable and could be useful not only for respiration monitoring, but in making PACU discharge decisions and adjusting opioid dosage on general hospital floor. Future studies are needed to evaluate the potential clinical utility of such an integrated respiration monitor.

Assessment of a new volumetric capnography-derived parameter to reflect compression quality and to predict return of spontaneous circulation during cardiopulmonary resuscitation in a porcine model.

We aimed to evaluate a volumetric capnography (Vcap)-derived parameter, the volume of CO2 eliminated per minute and per kg body weight (VCO2/kg), as an indicator of the quality of chest compression (CC) and to predict the return to spontaneous circulation (ROSC) under stable ventilation status. Twelve male domestic pigs were utilized for the randomized crossover study. After 4min of untreated ventricular fibrillation (VF), mechanical cardiopulmonary resuscitation and ventilation were administered. Following 5-min washout periods, each animal underwent two sessions of experiments: three types of CC quality for 5min stages in the first session, followed by advanced life support, consecutively in two sessions. Different CC quality had a significant effect on the partial pressure of end-tidal carbon dioxide (PetCO2), VCO2/kg, aortic pressure (mean), aortic systolic pressure, aortic diastolic pressure, right atrial pressure (mean), and carotid blood flow (P < 0.05). With the improvement in CC quality, the values of PetCO2 and VCO2/kg also increased, and the difference between the groups was statistically significant (P < 0.05). The Spearman rank test revealed a significant correlation between the Vcap-derived parameters and hemodynamics. PetCO2 and VCO2/kg have similar capabilities for discriminating survivors from non-survivors, and the area under the curve for both was 0.97. VCO2/kg had similar performance as PetCO2 in reflecting the quality of CC and prediction of achieving ROSC under stable ventilation status in a porcine model of VF-related cardiac arrest. However, VCO2/kg requires a longer time to achieve a stable state after adjusting for quality of CC than PetCO2.

End‐tidal CO2 and transcutaneous CO2: Are we ready to replace arterial CO2 in awake children?

AbstractIntroductionArterial blood gas analysis (ABG) is the gold standard test for carbon dioxide measurement. End‐tidal PCO2 (PetCO2) and transcutaneous PCO2 (PtcCO2) are noninvasive alternative methods.ObjectiveTo examine the use of PetCO2 and PtcCO2 as PaCO2 surrogates in awake children.MethodsA prospective observational study. Consecutive awake children in a stable condition referred to the Sleep Unit of Hospital de Pediatría Dr. J. P. Garrahan with suspected or confirmed sleep‐related respiratory disorders requiring ABG were included. PetCO2 and PtcCO2 were recorded simultaneously during arterial puncture. PetCO2 and PtCO2 values were compared with PaCO2. Correlation coefficient and Bland–Altman analysis were applied. The sample size was calculated considering a mean difference ≤3 mmHg as clinically acceptable.ResultsSixty‐eight sample sets were obtained from 67 patients. The median age was 9.11 years (0.23–18.76). During 94.1% of the procedures patients breathed spontaneously, 30% needed multiple punctures and 92% resulted in pain. Median (IQR) PaCO2 (mmHg) was 36.3 (31.45; 40.90), PetCO2 33.0 (29; 39) and PtcCO2 38.8 (32.95; 43.32). Correlation and agreement for PaCO2/PetCO2 and PaCO2/PtcCO2 was r = .6 and .9, and media of bias = 2.83 (−9.97; 15.64) and −1.88 (−9.01; 5.24), respectively. Hypercapnia (PaCO2 &gt; 45.0 mmHg) was present in 8/68 (11.8%) samples. Sensitivity, specificity, positive predictive value and negative predictive value to detect hypercapnia with PetCO2 was 38%, 98%, 75%, and 92%, respectively, and with PtcCO2, 100%, 90%, 57%, and 100%, respectively.ConclusionPtcCO2 showed better agreement with PaCO2 than PetCO2 but because of the wide dispersion of values, neither method can replace the gold standard. Transcutaneous CO2 might be a good screening tool to detect hypercapnia in awake children.

The physiological effect of early pregnancy on a woman's response to a submaximal cardiopulmonary exercise test.

Given all its systemic adaptive requirements, pregnancy shares several features with physical exercise. In this pilot study, we aimed to assess the physiological response to submaximal cardiopulmonary exercise testing (CPET) in early pregnancy. In 20 healthy, pregnant women (<13 weeks gestation) and 20 healthy, non‐pregnant women, we performed a CPET with stationary cycling during a RAMP protocol until 70% of the estimated maximum heart rate (HR) of each participant. Hemodynamic and respiratory parameters were non‐invasively monitored by impedance cardiography (PhysioFlow®) and a breath‐by‐breath analyzer (OxyconTM). To compare both groups, we used linear regression analysis, adjusted for age. We observed a similar response of stroke volume, cardiac output (CO) and HR to stationary cycling in pregnant and non‐pregnant women, but a slightly lower 1‐min recovery rate of CO (−3.9 [−5.5;‐2.3] vs. −6.6 [−8.2;‐5.1] L min−1 min−1; p = .058) and HR (−38 [−47; −28] vs. −53 [−62; −44] bpm/min; p = .065) in pregnant women. We also observed a larger increase in ventilation before the ventilatory threshold (+6.2 [5.4; 7.0] vs. +3.2 [2.4; 3.9] L min−1 min−1; p < .001), lower PETCO2 values at the ventilatory threshold (33 [31; 34] vs. 36 [34; 38] mmHg; p = .042) and a larger increase of breathing frequency after the ventilatory threshold (+4.6 [2.8; 6.4] vs. +0.6 [−1.1; 2.3] breaths min−1 min−1; p = .015) in pregnant women. In conclusion, we observed a slower hemodynamic recovery and an increased ventilatory response to exercise in early pregnancy.

Carbon dioxide elimination pattern in assessing the risk of an unfavorable outcome in cardiac surgery

Aim. To assess the influence of resting partial pressure of end-tidal carbon dioxide (PetCO2) levels on the long-term results of cardiac surgery.Materials and methods. This prospective cohort study included 454 patients with coronary artery disease who underwent elective coronary artery bypass graft surgery. Before surgery, all patients underwent pulmonary function tests, including body plethysmography, lung diffusion capacity assessment and cardiopulmonary exercise testing with the determination of ventilatory and gas exchange parameters, including PetCO2 at rest. The endpoint was the 2-year survival rate after surgery.Results. Parameters characterizing the obstructive breathing pattern, the lung diffusion capacity, and resting PetCO2 levels had a significant predictor value in relation to long-term survival after cardiac surgery. Among the baseline clinical and functional characteristics, a significant influence on long-term results was shown by the EuroSCORE II (OR 1,69 (1,26-2,27), p=0,001). The highest sensitivity and specificity in relation to long-term mortality risk after coronary artery bypass grafting was shown by resting PetCO2 value equal to 31 mm Hg (area under the ROC curve 0,74 (0,64-0,86), p&lt;0,001).Conclusion. The resting PetCO2 level below 31 mm Hg in patients with coronary artery disease showed a significant effect on the increased long-term mortality risk after cardiac surgery, which is important for patients with exercise intolerance.

Cerebral Autoregulation Is Not Different Between Hot And Thermoneutral Head-Out Water Immersion In Healthy Participants

Recurring hot head-out water immersion (HOWI) enhances peripheral vascular function and cerebral blood velocity during non-immersion conditions (i.e., rest, aerobic exercise, and heat stress). However, it is not known if an acute bout of hot HOWI alters cerebrovascular function (i.e., cerebral autoregulation). PURPOSE: We tested the hypothesis that dynamic cerebral autoregulation is improved during and following an acute bout of hot (HOT) vs. thermoneutral (TN) HOWI. METHODS: Seventeen healthy participants (age: 23±2 y, 5 females) completed two randomized trials which consisted of 30 min of HOT (39°C) or TN (35°C) HOWI. Beat-to-beat blood pressure (MAP), middle cerebral artery blood velocity (MCAv), and end-tidal CO2 tension (PETCO2) were recorded continuously. After 5 min of seated rest, participants breathed through a respiratory impedance device for 5 min while maintaining PETCO2 values to assess cerebral autoregulation using Fourier transformation (n = 11). Cerebral autoregulation testing was completed pre, 30 min into HOWI (during), and immediately post HOWI. Values are reported as a change from baseline (α: mean ± SD). RESULTS: MAP, MCAv, PETCO2, gain, and phase were not different between HOT and TN at pre (P > 0.23 for all). αMAP was lower in HOT vs. TN during (-3±6 vs. 9±5 mmHg; P<0.01) and post (0±5 vs. 10±7 mmHg; P<0.01). αMCAv was lower in HOT vs. TN during (-3±5 vs. 4±4 cm/s; P<0.01) and post (-5±7 vs. 0±5 cm/s; P<0.01). αPETCO2 was lower in HOT vs. TN during (1±2 vs. 2±2 mmHg; P<0.01) and post (-3±2 vs. -1±2 mmHg; P<0.01). αGain was not different between HOT and TN during (HOT: -0.03±0.15 vs. TN: -0.08±0.05 cm/s/mmHg; P=0.18) or post (HOT: 0.04±0.12 vs. TN: -0.03±0.07 cm/s/mmHg; P=0.18). αPhase was not different between HOT and TN during (HOT: 2.9±9.0 vs. TN: 1.0±8.8°; P=0.74) or post (HOT: -1.2±12.8 vs. TN: -2.0±9.7°; P=0.74) CONCLUSION: These data indicate that an acute bout of hot water immersion attenuates cerebral blood velocity vs. thermoneutral water immersion. This response is likely due to the differences in arterial blood pressure and/or arterial carbon dioxide between conditions. However, cerebral autoregulation during and following hot water immersion is not different compared to thermoneutral water immersion in healthy participants. Supported by Office of Naval Research Award N00014-17-1-2665