A Persistently High End-Tidal Carbon Dioxide Value: Can This Be Spurious?

Prolonged exercise in a hot environment increases the minute ventilation (VE) and respiratory rate (RR) with an increase in core temperature. This hyperthermia-induced hyperventilation decreases the partial pressure of arterial blood carbon dioxide (PaCO2). Conversely, nasal breathing during exercise has been reported to produce low VE and RR values and high PaCO2 values; however, no studies have investigated this in hot environments. Therefore, the purpose of this study was to clarify the effect of nasal breathing on estimated partial pressure of carbon dioxide in arterial blood (PaCO2,estimate) during prolonged exercise in a hot environment. Twelve university endurance athletes participated in the study and performed a 40-minutes steady-state cycling exercise at an intensity of 55% of peak oxygen uptake in a hot environment (room temperature 35℃, relative humidity 40%). Using randomized crossover design, two experiments were performed—nasal breathing condition (NB) and mouth breathing condition (MB). Moreover, physiological indices were measured during the exercise. Rectal temperature increased in both conditions, but there was no significant difference between these conditions. PaCO2,estimate values were significantly higher in NB between 10 minutes and 40 minutes of exercise (p < 0.05) compared to MB, and decreased with time in MB. Compared to MB, the VE was significantly lower in NB between 30 minutes and 40 minutes (p < 0.05), while the RR was significantly lower in NB between 25 minutes and 40 minutes of exercise (p < 0.05). Therefore, nasal breathing during a prolonged moderate-intensity exercise in a hot environment prevented the decrease in PaCO2,estimate due to hyperthermia-induced hyperventilation.

Objective To investigate the clinical effects of modified pulmonary infection control window guided invasive-noninvasive sequential ventilation in the treatment of acute exacerbation chronic pulmonary disease (AECOPD) with respiratory failure. Methods Fifty AECOPD patients with respiratory failure treated in Xuzhou First People’s Hospital from January 2015 to June 2018 were selected and divided into observation group and control group by random number table method. The control group was given tracheal intubation and mechanical ventilation, while the observation group was given invasive-noninvasive sequential ventilation under the guidance of improved pulmonary infection control window. The therapeutic effects of the two groups were compared. Results The total hospitalization time, total mechanical ventilation time, invasive mechanical ventilation time and intensive care unit stay time in the observation group were shorter than those in the control group (P<0.05). And the respiratory rate, heart rate and ventilation-associated pneumonia incidence were less than those in the control group (P<0.05). After treatment, the levels of partial pressure of oxygen in arterial blood, pH and end-tidal carbon dioxide tension in both groups increased (P<0.05); while partial pressure of carbon dioxide in arterial blood decreased, and the changes in the observation group were more significant (P<0.05). Forced expiratory volume in 1 second, forced expiratory flow at 25% to 50% increased significantly after treatment, and the increases in the observation group were more significant (P<0.05). Conclusions Modified pulmonary infection control window guided invasive-noninvasive sequential ventilation is effective in the treatment of AECOPD with respiratory failure. It can improve pulmonary ventilation and blood gas index, alleviate inflammatory response, and effectively improve prognosis. Key words: Pulmonary infection control window; Invasive-noninvasive sequential ventilation; Acute exacerbation chronic pulmonary disease with respiratory failure

Aim of the Study: End tidal carbon dioxide (EtCO 2 ) monitoring is considered to reflect real-time estimation of partial pressure of carbon dioxide in arterial blood (PaCO 2 ) noninvasively. However, knowledge about its relationship with PaCO 2 in critically ill pediatric and neonatal patients is limited. The primary objective was to evaluate predictive capability of end tidal carbon dioxide monitoring and secondary objective was to determine the influence of severity of lung disease on EtCO 2 and PaCO 2 relationship. Materials and Methods: This was a prospective, nonrandomized, consecutive enrollment study carried out in neonatal and pediatric intensive care units of a tertiary care children hospital. It was conducted in 66 neonates and 35 children receiving mechanical ventilation. Severity of lung disease was estimated by ventilation index and PaO 2 /FiO 2 (P/F) ratio. Simultaneous recording of EtCO 2 and PaCO 2 levels was done and data were analyzed for correlation and agreement. Results: In neonates , 150 EtCO 2 and PaCO 2 pairs were recorded. The mean weight ± SD of patients was 2.1 ± 0.63 kg. PaCO 2 had a positive correlation with EtCO 2 ( r = 0.836, 95% CI = 0.78-0.88). P/F ratio 2 had an excellent correlation with EtCO 2 ( r = 0.914, 95% CI = 0.87 and 0.94). P/F ratio Conclusion: EtCO 2 monitoring displayed a good validity to predict PaCO 2 . Correlation was affected by low P/F ratio ( 2 values.

Aim of the Study:End tidal carbon dioxide (EtCO2) monitoring is considered to reflect real-time estimation of partial pressure of carbon dioxide in arterial blood (PaCO2) noninvasively. However, knowledge about its relationship with PaCO2 in critically ill pediatric and neonatal patients is limited. The primary objective was to evaluate predictive capability of end tidal carbon dioxide monitoring and secondary objective was to determine the influence of severity of lung disease on EtCO2 and PaCO2 relationship.Materials and Methods:This was a prospective, nonrandomized, consecutive enrollment study carried out in neonatal and pediatric intensive care units of a tertiary care children hospital. It was conducted in 66 neonates and 35 children receiving mechanical ventilation. Severity of lung disease was estimated by ventilation index and PaO2/FiO2 (P/F) ratio. Simultaneous recording of EtCO2 and PaCO2 levels was done and data were analyzed for correlation and agreement.Results:In neonates, 150 EtCO2 and PaCO2 pairs were recorded. The mean weight ± SD of patients was 2.1 ± 0.63 kg. PaCO2 had a positive correlation with EtCO2 (r = 0.836, 95% CI = 0.78-0.88). P/F ratio <200 adversely affected relationship. In infants and children, 96 pairs were recorded. Mean age ± SD of patients was 4.20 ± 4.92 years and mean weight ± SD was 13.1 ± 9.49 kg. PaCO2 had an excellent correlation with EtCO2 (r = 0.914, 95% CI = 0.87 and 0.94). P/F ratio <200 adversely affected relationship.Conclusion:EtCO2 monitoring displayed a good validity to predict PaCO2. Correlation was affected by low P/F ratio (<200); hence, it is recommended that blood gases be measured in these patients until such time that a good relation can be established between end tidal and arterial CO2 values.

The effects of surgical technique on respiratory mechanics, arterial oxygenation and hemodynamics in radical prostatectomy operation were investigated. The study was planned on ASA II-III, 40-65 years old, fourty patients scheduled for radical prostatectomy under general anesthesia. They were divided into two groups: perineal and suprapubic (Group P, n = 20; Group S, n = 20). Heart rate, mean arterial blood pressure, arterial oxygen saturation (SpO2), partial pressure of end-tidal carbon dioxide (PEtCO2), Peak inspiratory pressure (PIP), plato pressure (Pplato), partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2) values were evaluated at 10 minutes after induction. After the position applied for surgery in the 30.60 and 90th minutes, the Alveolar-arterial oxygen pressure gradient (P(A-a) O2), the ratio of physiologic dead space over tidal volume (VD/VT), arterial to end tidal CO2 gradient (P(a-et) CO2), static compliance (CS), dynamic compliance (CD) were assessed. In the assessment of groups, there were not statistical differences about mean blood pressure, heart rate, SpO2, PetCO2, PaO2, plateau pressure, and P (A-a) values (p &gt; 0.05). Peak inspiratory pressure was higher in Group P. Peak inspiratory pressure and plateau pressure increased with CO2 insufflation in Group P. PaCO2 and P(a-et) CO2 were higher statistically significantly in Group 0. There was no difference in terms of the PetCO2 values. VD/VT ratios were statistically significantly lower in the Group P. Suprapubic surgery was shown to improve oxygenation and respiratory mechanics without causing any hemodynamic side effect in radical prostatectomy operation.

Objective: The effects of 10cmH2O Positive End-expiratory Pressure (PEEP) on respiratory mechanics, arterial oxygenation and hemodynamics in laparoscopic cholecystectomy operation were investigated. Methods: The study was planned on ASA I-II, 18-65 years old, forty patients scheduled for laparoscopic cholecystectomy under general anesthesia. The patients were divided into two groups which PEEP implemented Group 0 and 10 cmH2O PEEP applied Group P (Group 0, n=20; Group P, n=20). Heart rate, Mean arterial blood pressure, arterial oxygen saturation (SpO2), partial pressure of end-tidal carbon dioxide (PEtCO2), Peak inspiratory pressure (PİP), plato pressure (Pplato), partial pressure of oxygen in arterial blood (PaO2), partial pressure of carbon dioxide in arterial blood (PaCO2 ) values were evaluated at 5 minutes after induction, 5 minutes after CO2 insufflation, after the head-up position and the right side in the 10th and 30th minutes, After 10 minutes desufflation and in the recovery room. The Alveolar–arterial oxygen pressure gradient (P(A-a) O2), the ratio of physiologic dead space over tidal volume (VD/VT), Arterial to End Tidal CO2 gradient (P(a-et) CO2), static compliance (CS), dynamic compliance (CD) were assessed same times. Results: The assessment between the groups, there were not statistical differences about mean blood pressure, heart rate, SpO2, PetCO2, PaO2, plateau pressure, and P (A-a) values (p>0.05). Peak inspiratory pressure was higher in Group P (p<0.05). Peak inspiratory pressure and plateau pressure increased with CO2 insufflation in both groups. PaCO2 and P(a-et) CO2 were higher statistically significantly in Group 0 (p<0.05). There was no difference between the groups in terms of the PetCO2 values. VD/VT ratios were statistically significantly lower in the Group P (p<0.05). There was no difference at static compliance values between the groups, dynamic compliance was lower in Group P. According to the initial values, there was a decrease in compliance in both groups after CO2 insufflation. Conclusion: 10 cmH2O PEEP was shown to improve oxygenation and respiratory mechanics without causing any hemodynamic side effect in laparoscopic cholecystectomy operation.

Background Ventilation strategies during general anesthesia are crucial for optimizing respiratory mechanics, ensuring adequate oxygenation, and minimizing postoperative pulmonary complications (PPCs) in surgical patients. This systematic review and network meta-analysis (NMA) aim to evaluate the effect of pressure controlled volume guaranteed ventilation (PCV-VG) in patients undergoing non-cardiothoracic surgery. Methods We selected randomized controlled trials (RCTs) to explore the effect of PCV-VG mode on intraoperative respiratory mechanics, oxygenation and PPCs in surgical patients published in English by searching PubMed, Embase, Web of Science, and the Cochrane from inception to May 2025. The primary outcome was dynamic lung compliance (Cdyn). Results Fourteen studies with 2263 patients were included. Compared to volume-controlled ventilation (VCV), PCV-VG had higher Cdyn and lower airway peak pressure (Ppeak). For tidal volume (Vt), partial pressure of carbon dioxide in arterial blood (PaCO2), partial pressure of oxygen in arterial blood (PaO2), oxygenation index (OI), airway mean pressure (Pmean), and PPCs, there were no significant difference among pressure-controlled ventilation (PCV), VCV, and PCV-VG. Compared to VCV, PCV-VG did not significantly affect the values of potential of hydrogen (pH) and partial pressure of end-tidal carbon dioxide (PetCO2). The subgroup analysis only showed that PCV had higher Cdyn than VCV in prone position. Conclusions PCV-VG was superior to VCV in Cdyn and Ppeak, PCV only achieved higher Cdyn than VCV for prone position. The three modes did not differ in Vt, Pmean, PetCO2, pH, PaCO2, PaO2, OI, and PPCs for patients undergoing non-cardiothoracic surgery.

With the development of healthcare concepts, nursing interventions are gradually being emphasized in the treatment of chronic obstructive pulmonary disease (COPD) patients. This study aims to explore the impact of emergency nursing interventions on outcomes for patients with COPD. Eighty-four patients with COPD were included in the analysis, the control group received routine nursing (42 cases), and the research group received emergency nursing (42 cases). We compared the pulmonary functions of the 2 groups: forced vital capacity, peak expiratory flow, forced expiratory volume in the first second; blood gas parameters: partial pressure of oxygen in arterial blood, partial pressure of carbon dioxide in arterial blood; dyspnea: modified Medical Research Council (mMRC) score; quality of life: COPD Assessment Test (CAT) score; exercise tolerance: 6-minute walk distance; and mental status: self-rating depression scale (SDS) and self-rating anxiety scale (SAS) scores. P < .05 indicates statistically significant difference. After the intervention, forced vital capacity (3.93 ± 0.90 L vs 2.95 ± 0.85 L), peak expiratory flow (7.30 ± 1.16 L/min vs 6.39 ± 1.13 L/min), and forced expiratory volume in the first second (3.59 ± 0.66 L vs 2.83 ± 0.83 L) levels in the research group were significantly better than those in the control group (P < .001). Partial pressure of oxygen in arterial blood (86.56 ± 5.74 mm Hg vs 78.16 ± 5.91 mm Hg) was significantly higher and partial pressure of carbon dioxide in arterial blood (54.09 ± 5.08 mm Hg vs 69.26 ± 7.58 mm Hg) was significantly lower in the research group compared to the control group (P < .001). The mMRC and CAT scores were reduced in both groups, and the mMRC (1.62 ± 0.66 vs 2.21 ± 0.65, P < .001) and CAT (16.64 ± 3.93 vs 19.29 ± 4.31, P = .004) scores were significantly lower in the research group than in the control group. The 6-minute walk distance (449.83 ± 47.49 vs 407.79 ± 44.98, P < .001) was significantly longer in the research group than in the control group. In addition, SDS and SAS scores decreased in both groups after the intervention, and SDS (37.38 ± 4.50 vs 41.93 ± 4.05, P < .001) and SAS (38.21 ± 4.04 vs 42.14 ± 3.80, P < .001) scores were also significantly lower in the research group than in the control group. Emergency nursing intervention significantly improved pulmonary function, quality of life, exercise tolerance, and psychological health of COPD patients, which has important clinical promotion value.

BackgroundAn exacerbation of asthma is an episode, characterized by a progressive increase in one or more typical asthma symptoms (shortness of breath, wheezing, cough, and chest tightness).Copeptin is a 39-amino acid glycopeptide that is derived from the c-terminal part of the pre–pro-hormone of arginine vasopressin.AimThe aim of our study was to evaluate the role of copeptin in asthmatic patients and its relationship to disease severity.Patients and methodsThis was a prospective observational study carried out on 45 patients during acute exacerbation of bronchial asthma (15 mild, 15 moderate, and 15 severe cases) and 15 healthy participants.ResultsOur study showed no significant difference in age, sex, and BMI between case and control groups. There was a statistical highly significant differences in pulmonary function tests, partial pressure of oxygen in arterial blood, partial pressure of carbon dioxide in arterial blood, and oxygen saturation among mild, moderate, and severe cases, and significant increase in total leukocytic count and hospital stay in severe cases than mild and moderate cases. There was a highly significant increase of plasma copeptin in moderate and severe cases than mild cases and control groups. There were nonsignificant correlations between copeptin and pulmonary function tests in mild cases; a significant negative correlation between copeptin and forced expiratory volume in 1 s (FEV1) actual in moderate cases; significant negative correlations between copeptin, FEV1 actual, FEV1% predicted, forced vital capacity% predicted, and peak expiratory flow% predicted in severe cases; and highly significant negative correlations between copeptin and partial pressure of oxygen in arterial blood and oxygen saturation in all cases (P<0.001). Partial pressure of carbon dioxide in arterial blood exhibited a nonsignificant positive correlation with copeptin (P<0.05).ConclusionCopeptin is proven to be a novel biomarker and is increased in patients with asthma as compared with healthy controls.

The aim of this study was to determine whether a pneumoperitoneum of 10 mmHg combined or not with the Trendelenburg position could lead to significant changes in intraocular pressure (IOP), ocular pressure perfusion (OPP), and cardiorespiratory variables; as well as determine whether a correlation exists between IOP and mean arterial blood pressure (MAP), and/or partial pressure of carbon dioxide in arterial blood (PaCO2) in cats. Animals were allocated in two groups (n=7/group): GC (without inclination) and GTREN (Trendelenburg position). The variables were recorded before (baseline) and during 30 minutes (T5-T30) after insufflation. In GTREN, a reduction in heart rate was observed at T5 and in respiratory rate at T5 and T15. There was an increase in IOP at T5-T30 in comparison to baseline. There was a reduction in potential of hydrogen in arterial blood in both groups at all times in comparison to baseline. Partial pressure of carbon dioxide in arterial blood was increased at T15-T30 in GC and at T5-T30 in GTREN. In conclusion, the pneumoperitoneum of 10mmHg CO2 did not significantly affect IOP or OPP in cats anaesthetised with isofluorane and kept under spontaneous ventilation. However, induced pneumoperitoneum combined with Trendelenburg position resulted in an increase in IOP in cats subjected to the same anaesthetic conditions, but did not affect OPP.

Abstract. The work is devoted to the study of arterial blood gas parameters and comparison of capnographic determination of carbon dioxide at the end of exhalation (EtCO2) and the real pressure of carbon dioxide in arterial blood (paCO2) depending on the degree of morbid obesity in patients who were to undergo surgical bariatric interventions in 2012-2021. The study included 61 patients, whose age ranged from 22 to 69 years, body mass index from 40 to 91 kg/m2. The patients were divided into 3 groups depending on the degree of morbid obesity: group 1 - 20 patients with body mass index ≥ 40 (grade 3); group 2 - 25 patients with body mass index ≥ 50 (grade 4); group 3 - 16 patients with body mass index ≥ 60 (grade 5). Based on the data obtained, it was found that the state of the arterial blood gas composition indicates the presence of respiratory function disorders in patients with morbid obesity, which significantly reduce the compensatory capabilities of the body. Arterial hemoglobin saturation with oxygen (SaO2) tended to decrease, reaching a minimum in patients of the 1st group. The studied parameters of the arterial blood gas composition in patients of group 1 tended to worsen, and in patients of groups 2 and 3 they significantly worsened with an increase in the degree of morbid obesity. The maximum disruption of arterial blood gases was found in patients with a body mass index ≥ 60. The partial pressure of carbon dioxide at the end of exhalation (EtCO2) in patients with morbid obesity does not correspond to the partial pressure of carbon dioxide in arterial blood (paCO2).

In the present study the partial pressure of carbon dioxide in arterial blood (PaC0:1 and respiratory rate (RR) were studied in pregnant and non-pregnant women in Dhaka city. Far this purpose a total 32 women for PaCO)and 100 women for RR with age ranging front 25 ...ears le 35 years without any recent history of respiratory diseases were selected. Normal pregnant women were taken as e.yperimental group and healthy nor-pregnant ...omen as return!. Data was collected during first trimester. second trimester and third trimester in pregnant women and also nompregnant women. The PaCOrwas determined by using 'EASY BLOOD GAS .0TO INALMER" and RR was recorded. The PaCO, and RR during different trimesters of pregnant .rumen were compared with that of non-pregnant 11.1101. Statistical analysis was drum with .tudents '1' rest. The PeCOr was significantly lower in first trimester, second trimester and third (rimester of pregnant women than that of non-pregnant women. Similarly, RR was significantly higher in first trimester. second trimester and third trimester of pregnant women than that of nonpregnant women. Again RR was significantly higher in third trimester than in first trimester and second trimester of pregnant women. There were no statistically significant difference of PaCO, among first trimester. second trimester and third trimester of pregnant women. Similarly, there were no statistically significant difference of RR between first trimester and second trimester of pregnant women. It may be concluded from the study that the progressively decreased PaCO• and increased RR throughout Me pregnancy were most likely MP be related to the effect of progesterone-induced hyperventilation. Hypermfilation in pregnancy is due to hypersensitivity of respiratory centre. Due to hyperventilation there is expel out of CO, miming decrease in PaC0r and increase in RR during pregnancy.

PurposeWe aimed to evaluate sleep-related hypoventilation in multiple system atrophy (MSA) using polysomnography (PSG) with transcutaneous partial pressure of carbon dioxide (PtcCO2) monitoring.MethodsThis prospective study included 34 patients with MSA. Motor and autonomic function, neuropsychological tests, PSG with PtcCO2 monitoring, and pulmonary function tests were performed. Sleep-related hypoventilation disorder (SRHD) was defined according to the International Classification of Sleep Disorders, third edition.ResultsNine (27%) of the 34 patients met the diagnostic criteria of SRHD. Twenty-nine (85%) patients had sleep-related breathing disorders based on an Apnea–Hypopnea Index of ≥ 5/h. The patients with MSA and SRHD had a higher arousal index (p = 0.017) and obstructive apnea index (p = 0.041) than those without SRHD. There was no difference in the daytime partial pressure of carbon dioxide in arterial blood or respiratory function between MSA patients with and without SRHD.ConclusionSleep-related hypoventilation may occur in patients with MSA even with a normal daytime partial pressure of carbon dioxide. This can be noninvasively detected by PSG with PtcCO2 monitoring. SRBD and sleep-related hypoventilation are common among patients with MSA, and clinicians should take this into consideration while evaluating and treating this population.Supplementary InformationThe online version contains supplementary material available at 10.1007/s11325-022-02568-4.

Chronic Obstructive Pulmonary Disease (COPD) patients generally present with respiratory acidosis and type 2 respiratory failure. Here we present a case of 65 years old female, who is a known case of COPD and presented in our emergency department with severe metabolic alkalosis (pH 7.730, HCO3- greater than 99.9mmol/l). She was referred from other center after the development of seizure. Urinary sodium was sent which indicated the cause of metabolic alkalosis was contraction alkalosis; we then treated the patient with IV fluids, antibiotics and Mechanical Ventilator. Arterial Blood gas analysis was initially done every 4 hours till the pH was corrected. After pH was corrected the patient was extubated to intermitted Non Invasive Ventilation (NIV) for type 2 respiratory failure. With pulmonary rehabilitation we could discharge the patient with inhalers; without the need for NIV or supplementary oxygen. This is one of the rare cases where the patient presented with a very high bicarbonate level, high partial pressure of carbon dioxide in arterial blood, and high pH. The patient was successfully managed with IV fluids and mechanical ventilation.

Flail chest is an uncommon consequence of traumatic injury. Medical management includes mechanical ventilation for internal pneumatic stabilization. Control of respiratory drive is necessary to avoid paradoxical movement and impairment of recovery. Traditional approaches include sedation and neuromuscular blockade, but these measures are at odds with current trends of keeping patients awake and implementing active rehabilitation. We hypothesized that extracorporeal carbon dioxide removal (ECCO2R) would suppress the respiratory drive sufficiently to permit synchronous mechanical ventilation, allowing rib fracture healing in an awake patient with extensive bilateral flail chest. A patient with 21 fractures underwent ECCO2R for 6 weeks to permit internal pneumatic stabilization with mechanical ventilation, targeting a partial pressure of carbon dioxide in arterial blood (PaCO2) of 25-30 mm Hg. The first 2 weeks were performed with extracorporeal membrane oxygenation (ECMO) for bilateral pulmonary contusions and acute respiratory distress syndrome. The last 4 weeks was with low-flow ECCO2R. Respiratory drive was suppressed during both ECMO and ECCO2R phases when the targeted hypocapnia range of 25-30 mm Hg was achieved, permitting synchronous positive pressure ventilation in an awake and cooperative patient undergoing active rehabilitation. Extracorporeal carbon dioxide removal targeting hypocapnia is a potential adjunct in extensive flail chest injury undergoing nonsurgical management.