End-Tidal Carbon Dioxide Pressure Measurement after Prolonged Inspiratory Time Gives a Good Estimation of the Arterial Carbon Dioxide Pressure in Mechanically Ventilated Patients

Background: End-tidal carbon dioxide pressure (PetCO2) is unreliable for monitoring PaCO2 in several conditions because of the unpredictable value of the PaCO2–PetCO2 gradient. We hypothesised that increasing both the end-inspiratory pause and the expiratory time would reduce this gradient in patients ventilated for COVID-19 with Acute Respiratory Distress Syndrome and in patients anaesthetised for surgery. Methods: On the occasion of an arterial blood gas sample, an extension in inspiratory pause was carried out either by recruitment manoeuvre or by extending the end-inspiratory pause to 10 s. The end-expired PCO2 was measured (expiratory time: 4 s) after this manoeuvre (PACO2) in comparison with the PetCO2 measured by the monitor. We analysed 67 Δ(a-et)CO2, Δ(a-A)CO2 pairs for 7 patients in the COVID group and for 27 patients in the anaesthesia group. Results are expressed as mean ± standard deviation. Results: Prolongation of the inspiratory pause significantly reduced PaCO2–PetCO2 gradients from 11 ± 5.7 and 5.7 ± 3.4 mm Hg (p < 0.001) to PaCO2–PACO2 gradients of −1.2 ± 3.3 (p = 0.043) and −1.9 ± 3.3 mm Hg (p < 0.003) in the COVID and anaesthesia groups, respectively. In the COVID group, PACO2 showed the lowest dispersion (−7 to +6 mm Hg) and better correlation with PaCO2 (R2 = 0.92). The PACO2 had a sensitivity of 0.81 and a specificity of 0.93 for identifying hypercapnic patients (PaCO2 > 50 mm Hg). Conclusions: Measuring end-tidal PCO2 after prolonged inspiratory time reduced the PaCO2–PetCO2 gradient to the point of obtaining values close to PaCO2. This measure identified hypercapnic patients in both intensive care and during anaesthesia.

Carbon dioxide as a line active agent: Its impact on line tension and nucleation rate

By considering a water capillary bridge confined between two flat surfaces, we investigate the thermodynamics of the triple line delimiting this solid–liquid–vapor system when supplemented in carbon dioxide. In more detail, by means of atom-scale simulations, we show that carbon dioxide accumulates at the solid walls and, preferably, at the triple lines where it plays the role of a line active agent. The line tension of the triple line, which is quantitatively assessed using an original mechanical route, is shown to be driven by the line excess concentrations of the solute (carbon dioxide) and solvent (water). Solute accumulation at the lines decreases the negative line tension (i.e., more negative) while solvent depletion from the lines has the opposite effect. Such an unprecedented quantitative assessment of gas-induced line tension modifications shows that the absolute value of the negative line tension increases upon increasing the carbon dioxide partial pressure. As a striking example, for hydrophilic surfaces, the line tension is found to increase by more than an order of magnitude when the carbon dioxide pressure exceeds 3 MPa. By considering the coupling between line and surface effects induced by gaseous adsorption, we hypothesize from the observed gas concentration-dependent line tension a nontrivial impact on heterogeneous nucleation of nanometric critical nuclei.

Prediction of the Course of Transient Tachypnea of the Newborn by Blood Laboratory Parameters at the Time of Admission

Background: Transient tachypnea of the newborn (TTN) is a common but mild respiratory problem seen in late preterm and term newborns. However, it may sometimes cause severe morbidity. Objectives: Therefore, biomarkers that can predict TTN severity may aid the clinician in determining the need for intensive care. Our aim was to identify whether blood gases and complete blood count parameters could be utilized to predict the severity of TTN.s Methods: We retrospectively examined the medical records of newborns (> 37 weeks gestation, > 2000 grams) diagnosed with TTN who were hospitalized in the Neonatal Intensive Care Unit (NICU) of Karabuk University Faculty of Medicine, Training and Research Hospital, Karabük/Turkey between June 2019 and June 2020. Patients were grouped according to the length of stay in the NICU. Group 1 included patients that did not require NICU monitoring after 48 hours, and group 2 included patients who continued to require NICU monitoring after 48 hours. Blood gases and complete blood count parameters were compared between the two groups. Results: During the study period, 91 newborns were hospitalized in the NICU due to respiratory distress. Thirty-nine patients who did not meet the inclusion criteria were excluded. Gestational age and birth weight were significantly lower in group 2 (P < 0.05). There were no significant differences between the groups in terms of leukocyte count, hemoglobin level, mean platelet volume (MPV), and platelet count. Partial carbon dioxide pressure (PCO2) was significantly elevated, and base excess (BE) was significantly greater in group 2. Conclusions: We determined a relationship between a prolonged stay in NICU and the levels of PCO2 and BE among patients hospitalized with a diagnosis of TTN. Therefore, PCO2 and BE values may be valuable to determine the prognosis of TTN in the early period. Despite being one of the most common causes of intensive care admission in the newborn population, there is limited data on the diagnosis, treatment, and prognosis of TTN; thus, we believe that our results will shed light on this problem.

Exercise end-tidal carbon dioxide pressure: a new prognostic marker after acute myocardial infarction?

Funding Acknowledgements Type of funding sources: None. Background Although several cardiopulmonary exercise testing (CPET) parameters have already proved to predict prognosis, there is increasing interest in finding variables that do not require maximal effort. End-tidal carbon dioxide pressure (PETCO2), an indirect indicator of cardiac output, is one of such variables. Studies in heart failure populations already suggest its role as a prognostic factor. However, data concerning other populations are still scarce. Purpose To assess the association between exercise PETCO2, cardiac biomarkers and systolic function following acute myocardial infarction (AMI) and to evaluate its potential prognostic role in this population. Methods A retrospective single-centre analysis was conducted including patients who underwent symptom-limited CPET early after AMI. We assessed PETCO2 at baseline (PETCO2-B), at anaerobic threshold (PETCO2-AT) and at peak exercise and calculated the difference between PETCO2-AT and PETCO2-B (PETCO2-difference). We analysed their association with B-natriuretic peptide (BNP), maximal troponin after AMI as well as with left ventricular ejection fraction (LVEF) 1 year after. Results We included 40 patients with a mean age of 56 years (87.5% male), assessed with CPET a median of 3 months after AMI (80% of which were ST-elevation myocardial infarctions). Average respiratory exchange ratio was 1,1 with 48% of patients not reaching maximal effort. Mean PETCO2-AT was 37mmHg, with a mean increase from baseline of 6mmHg (PETCO2-difference). There was a significant positive correlation between all the PETCO2 variables measured and BNP values at time of AMI and on follow-up (best correlation for PETCO2-AT with BNP at AMI hospitalization, r = 0.608, p &lt; 0.001). Maximal troponin was not correlated with PETCO2. Both PETCO2-AT and PETCO2-difference were significantly and positively correlated with LVEF 1-year post-AMI (r = 0.421, p = 0.040 and r = 0.511, p = 0.011, respectively). Conclusion PETCO2-AT and PETCO2-difference are both correlated with BNP, an established prognostic marker, and with medium-term systolic function after AMI, suggesting their potential prognostic role in this population. Further studies with larger samples are required to confirm the results of this pilot study and assess PETCO2 as a definite predictor of prognosis after AMI.

TOWARD A NONINVASIVE MEASUREMENT METHOD OF CO2 ARTERIAL PRESSURE

Until now, the measurement of carbon dioxide blood pressure is done ex vivo, using an invasive process. This paper describes a first step toward a novel noninvasive process for in vivo measurement of this pressure. As first approximation, the blood solution is modeled as a simple aqueous solution of carbon dioxide in a cylindrical rigid canalization. The drift flux model and the Young–Laplace equation are employed to describe the fluid behavior. The numerical model relates the carbon dioxide pressure through the mixture pressure and velocity. The spatial distributions of these parameters are implemented to create linear mathematical relations between the mean mixture pressure and the radial velocity variation. As long as we are interested in a noninvasive measuring of the carbon dioxide pressure, a response model is proposed to describe the ultrasound signal backscattered by the considered solution. The linear relations are applied to deduce the carbon dioxide pressure through the measured radial velocity difference, using two computing methods of ultrasound signal. A comparative study is made between them showing the more appropriate process to compute the carbon dioxide pressure.

GAMBARAN NILAI SATURASI OKSIGEN (SO2) DENGAN TEKANAN OKSIGEN (PO2) PADA PASIEN PENYAKIT JANTUNG KORONER (PJK) DI RUMAH SAKIT UMUM DAERAH JAYAPURA

Coronary heart disease (CHD) patients are equipped with blood tests to reinforce the diagnosis of the patient's disease. One of the parameters that is usually checked is blood gas analysis (AGD). One of the parameters of blood gas analysis (BGA) is oxygen saturation (SO2), oxygen pressure (PO2), and carbon dioxide pressure (PCO2). The purpose of this study was to determine the relationship between SO2, and PO2,at the Jayapura Regional General Hospital. This type of research is retrospective analytic. The sample of this study were coronary heart patients who underwent BGA xamination at the Jayapura General Hospital who met the inclusion criteria, so that 30 samples were obtained. The type of data is secondary data. With the mean value of SO2 is 96,1% and PO2 is 133,2 mmHg. The results of the relationship between SO2 and PO2 in coronary heart disease patients at Jayapura Regional Hospital are directly proportional, namely the decrease in SO2, PO2 will also decrease in CHD patients, with four people experiencing moderate hypoxemia, five people with normal PO2, and 21 people with PO2 is high because you have got a ventilator device.

Roles of periodic breathing and isocapnic buffering period during exercise in heart failure

In heart failure, exercise – induced periodic breathing and end tidal carbon dioxide pressure value during the isocapnic buffering period are two features identified at cardiopulmonary exercise testing strictly related to sympathetic activation. In the present review we analysed the physiology behind periodic breathing and the isocapnic buffering period and present the relevant prognostic value of both periodic breathing and the presence/absence of the identifiable isocapnic buffering period.