Agreement of Carbon Dioxide Levels Measured by Arterial, Transcutaneous and End Tidal Methods in Preterm Infants ≤28 Weeks Gestation

Arterial blood gas remains to be the gold standard in assessing the adequacy of ventilation. Noninvasive monitoring methods are shown to be useful in adults and pediatric patients. They are technically simple and cost effective, but their accuracy in the preterm infants 28 weeks gestational age (GA) at birth is not established. To determine the correlation of arterial, transcutaneous and end tidal carbon dioxide values in preterm infants <28 weeks GA in the first 24 hours after birth. Preterm infants <28 weeks GA who required mechanical ventilation at birth were prospectively studied. Infants with structural cardiopulmonary disorders, who required high frequency ventilation and who received sodium bicarbonate infusion were excluded. Arterial CO2 (PaCO2) values were compared simultaneously with end tidal CO2 (EtCO2) and transcutaneous CO2 (TcPCO2) values measured within the first four hours, at 12 and at 24 hours after birth. Intraclass correlation coefficients (ICC) were calculated. Bland-Altman analysis was done to assess the degree of bias and precision. Twenty five patients completed the study. The mean (SD) GA was 26.3 (1.0) weeks and birth weight was of 884 (139) grams. There were 16 male infants. All infants had respiratory distress syndrome. The ICC for the TcPCO2 at 4, 12 and 24 hrs were 0.51, 0.73 and 0.50 respectively. The ICC for the EtCO2 at 4, 12 and 24 hrs were 0.62, 0.56 and 0.56 respectively. The mean differences (bias) and SD of the differences (precision) in the readings at three time points are shown in Table 1. Carbon dioxide measurements at three time points Measurement Mean Difference (SD) from PaCO2 Carbon dioxide measurements at three time points Measurement Mean Difference (SD) from PaCO2 There was moderate correlation between both nonin-vasive methods and PaCO2. However, there was wide variation in the noninvasive CO2 values in individual patients.

Monitoring CO2 levels in intubated neonates is highly relevant in the face of complications associated with altered CO2 levels. Thus, this review aims to present the scientific evidence in the literature regarding the correlation between arterial carbon dioxide measured by non-invasive methods in newborns submitted to invasive mechanical ventilation. The search was carried out from January 2020 to January 2021, in the Scopus, Medline, The Cochrane Library, Web of Science, CINAHL and Embase databases. Also, a manual search of the references of included studies was performed. The main descriptors used were: “capnography,” “premature infant,” “blood gas analysis,” and “mechanical ventilation.” As a result, 221 articles were identified, and 18 were included in this review. A total of 789 newborns were evaluated, with gestational age between 22.8 and 42.2 weeks and birth weight between 332 and 4790 g. Capnometry was the most widely used non-invasive method. In general, the correlation and agreement between the methods evaluated in the studies were strong/high. The birth weight did not influence the results. The gestational age of fewer than 37 weeks implied, in its majority, a moderate correlation and agreement. Therefore, we can conclude that there was a predominance of a strong correlation between arterial blood gases and non-invasive methods, although there are variations found in the literature. Even so, the results were promising and may provide valuable data for future studies, which are necessary to consolidate non-invasive methods as a reliable and viable alternative to arterial blood gasometry.

Controlling arterial carbon dioxide is paramount in mechanically ventilated patients, and an accurate and continuous noninvasive monitoring method would optimize management in dynamic situations. In this study, we validated and further refined formulas for estimating partial pressure of carbon dioxide with respiratory gas and pulse oximetry data in mechanically ventilated cardiac arrest patients. A total of 4741 data sets were collected retrospectively from 233 resuscitated patients undergoing therapeutic hypothermia. The original formula used to analyze the data is PaCO2 -est1=PETCO2 +k[(PIO2 -PETCO2 )-PaO2 ]. To achieve better accuracy, we further modified the formula to PaCO2 -est2=k1 *PETCO2 +k2 *(PIO2 -PETCO2 )+k3 *(100-SpO2 ). The coefficients were determined by identifying the minimal difference between the measured and calculated arterial carbon dioxide values in a development set. The accuracy of these two methods was compared with the estimation of the partial pressure of carbon dioxide using end-tidal carbon dioxide. With PaCO2 -est1, the mean difference between the partial pressure of carbon dioxide, and the estimated carbon dioxide was 0.08kPa (SE ±0.003); with PaCO2 -est2 the difference was 0.036kPa (SE ±0.009). The mean difference between the partial pressure of carbon dioxide and end-tidal carbon dioxide was 0.72kPa (SE ±0.01). In a mixed linear model, there was a significant difference between the estimation using end-tidal carbon dioxide and PaCO2 -est1 (P<.001) and PaCO2 -est2 (P<.001) respectively. This novel formula appears to provide an accurate, continuous, and noninvasive estimation of arterial carbon dioxide.

The laryngeal mask airway (LMA) has become a popular tool for airway management in selected adult and pediatric patients undergoing routine surgical procedures. The relationship between end-tidal and arterial carbon dioxide during controlled ventilation via the LMA in infants under 10 kg has not been reported. After induction of general anesthesia, the LMA was placed in 12 healthy infants and mechanical ventilation initiated. After maintaining steady-state level of end-tidal carbon dioxide (minimum 5 min), an arterial blood sample was obtained and end-tidal carbon dioxide level noted. The laryngeal mask was then removed, the trachea intubated, and mechanical ventilation resumed with initial ventilatory variables. After reaching a steady-state level of end-tidal carbon dioxide, a second arterial sample was obtained and end-tidal carbon dioxide level noted. The mean end-tidal carbon dioxide and arterial partial pressure of carbon dioxide obtained during ventilation were 42.2 +/- 7.9 and 47.1 +/- 11.0 (LMA) and 37.4 +/- 4.6 and 42.6 +/- 6.7 (endotracheal tube), respectively. Analysis of differences between partial pressure of carbon dioxide and end-tidal carbon dioxide using the Bland and Altman method revealed bias+/-precision of 4.9 +/- 3.9 and 5.3 +/- 3.2 with ventilation via the laryngeal mask and endotracheal tube. Our data indicate that, while ventilating infants under 10 kg with LMA, end-tidal carbon dioxide is an accurate indicator of arterial partial pressure of carbon dioxide.

The laryngeal mask airway (LMA) has become a popular tool for airway management in selected adult and pediatric patients undergoing routine surgical procedures.The relationship between end-tidal and arterial carbon dioxide during controlled ventilation via the LMA in infants under 10 kg has not been reported. After induction of general anesthesia, the LMA was placed in 12 healthy infants and mechanical ventilation initiated. After maintaining steady-state level of end-tidal carbon dioxide (minimum 5 min), an arterial blood sample was obtained and end-tidal carbon dioxide level noted. The laryngeal mask was then removed, the trachea intubated, and mechanical ventilation resumed with initial ventilatory variables. After reaching a steady-state level of end-tidal carbon dioxide, a second arterial sample was obtained and end-tidal carbon dioxide level noted. The mean end-tidal carbon dioxide and arterial partial pressure of carbon dioxide obtained during ventilation were 42.2 +/- 7.9 and 47.1 +/- 11.0 (LMA) and 37.4 +/- 4.6 and 42.6 +/- 6.7 (endotracheal tube), respectively. Analysis of differences between partial pressure of carbon dioxide and end-tidal carbon dioxide using the Bland and Altman method revealed bias +/- precision of 4.9 +/- 3.9 and 5.3 +/- 3.2 with ventilation via the laryngeal mask and endotracheal tube. Our data indicate that, while ventilating infants under 10 kg with LMA, end-tidal carbon dioxide is an accurate indicator of arterial partial pressure of carbon dioxide. (Anesth Analg 1997;84:51-3)

High-frequency ventilation versus conventional ventilation: No winner—but no loser

After completing this article, readers should be able to: 1. Describe the epidemiology and pathophysiology of gastroesophageal reflux (GER) in preterm neonates. 2. Delineate the associations of GER with apnea, chronic lung disease, behavior, and growth of preterm infants. 3. Review the investigations used to evaluate GER in preterm infants. 4. Describe nonpharmacologic and pharmacologic therapies for GER. Gastroesophageal reflux (GER) is a normal physiologic event occurring across the age spectrum. It may contribute to a variety of disorders, including esophagitis, feeding problems, and airway disease in all age groups. (1) A large number of symptoms and signs have been purported to be caused by GER despite a lack of data showing a clear association between a specific symptom and GER. In preterm infants, empiric therapy often is administered using agents of unproven efficacy and safety to treat symptoms that likely are unrelated to GER. In a survey on management practices for GER in preterm infants, common treatment strategies included positioning (98%) and slopes (96%), histamine 2 (H 2) receptor antagonists (100%), feed thickeners (98%), antacids (96%), prokinetics (79%), proton pump inhibitors (PPIs) (65%), and dopamine receptor antagonists (53%). (2)(3) The safety, efficacy, and appropriate dosing recommendations for most medical therapies remain uncertain in neonates. In this review, we attempt to summarize the current literature regarding physiology, pathophysiology, and diagnostic and management strategies for GER pertinent to the neonate, with an emphasis on the preterm infant. GER describes the retrograde movement of stomach contents (air or feeding, liquid or semisolid, acid or alkaline, enzymes or bile salts) into the esophagus. GER disease (GERD) occurs when GER causes symptoms or signs such as pain, poor weight gain, esophagitis, hematemesis, and airway symptoms, including apnea, aspiration, recurrent pneumonia, chronic lung disease (CLD), or large airway inflammation. However, any of these symptoms or signs …

The rebreathing of carbon dioxide in vulnerable infants has been proposed as a hypothesis for Sudden Infant Death Syndrome (SIDS). A new device, Infant Crib Air (ICA), provides a continuous flow of filtered air to an infant's mouth and nose and was shown to decrease rebreathing of carbon dioxide in 21 healthy full term infants in their own cribs at home (Amer J Perinat 12:1995). Because these were infants at low risk for SIDS and the environment for each infant was so different, we chose to study preterm infants in a more controlled setting (using the same crib, same sleep position, same equipment, same room). Thirteen preterm infants of 30.2 ± 2.7 weeks gestational age (mean ± SD) who had successfully weaned from the incubator isolette for at least 2 days and projected to be ready for discharge within one week were enrolled. Infants were studied at 35.8 ± 1.9 weeks corrected age. Based on the previous report, we determined that 11 infants were necessary to obtain a 50% decrease in inspiratory carbon dioxide using ICA. All infants were placed on their side in the crib with the ICA manifold placed 20cm from their nose. An Ohmeda 5200 measured carbon dioxide levels. Inspiratory carbon dioxide, end tidal carbon dioxide, skin temperature, and room temperature were regularly measured for 30 minutes before and after starting the ICA device. We found that the mean inspiratory carbon dioxide significantly fell (p < 0.05) from a baseline of 4.5 torr to 2.6 torr and 2.1 torr when the air speed from the device was set at 0.5 mile per hour and 1 mile per hour respectively(p = N.S. 0.5 vs 1 mile per hour). There was no significant difference in the end tidal carbon dioxide levels on ICA. We found no significant difference in the room temperature (mean = 23.5° C) or the infant's skin temperature after 16 continuous hours of ICA exposure at one mile per hour air speed. We conclude that the ICA significantly lowers the inspiratory carbon dioxide in preterm infants. We speculate that this device may help reduce the risk of SIDS by decreasing the frequency of rebreathing exhaled air and may prevent overheating by continuously blowing air onto an infant's head and face.

Capnography: Clinical Aspects.

BackgroundMask leak and airway obstruction are common with mask ventilation in newborn infants, leading to suboptimal ventilation. We aimed to perform a pilot study measuring respiratory mechanics during one-person and...

ObjectiveThere are conflicting data regarding the use of end-tidal carbon dioxide (PetCO2) measurement in preterm infants. The aim of this study was to evaluate the effects of different dead space to tidal volume ratios (VD/VT) on the correlation between PetCO2 and arterial carbon dioxide pressure (PaCO2) in ventilated preterm infants with respiratory distress syndrome (RDS).MethodsWe enrolled ventilated preterm infants (with assist control mode or synchronous intermittent mandatory mode) with RDS who were treated with surfactant in this prospective study. Simultaneous PetCO2 and PaCO2 data pairs were obtained from ventilated neonates monitored using mainstream capnography. Data obtained before and after surfactant treatment were also analyzed.ResultsOne-hundred and one PetCO2 and PaCO2 pairs from 34 neonates were analyzed. There was a moderate correlation between PetCO2 and PaCO2 values (r = 0.603, P < 0.01). The correlation was higher in the post-surfactant treatment group (r = 0.786, P < 0.01) than the pre-surfactant treatment group (r = 0.235). The values of PaCO2 and PetCO2 obtained based on the treatment stage of surfactant therapy were 42.4 ± 8.6 mmHg and 32.6 ± 7.2 mmHg, respectively, in pre-surfactant treatment group, and 37.8 ± 10.3 mmHg and 33.7 ± 9.3 mmHg, respectively, in the post-surfactant treatment group. Furthermore, we found a significant decrease in VD/VT in the post-surfactant treatment group when compared to the pre-surfactant treatment group (P = 0.003).ConclusionsVD/VT decreased significantly after surfactant therapy and the correlation between PetCO2 and PaCO2 was higher after surfactant therapy in preterm infants with RDS.

Carbon dioxide clearance during apnoea with high-flow nasal oxygen: epiphenomenon or a failure to THRIVE?

Measuring energy expenditure in preterm and unstable infants

Monitoring carbon dioxide in patients on mechanical ventilation is crucial for critical care nurses. Monitoring the value of arterial carbon dioxide pressure involves invasive arterial blood gas analysis. Monitoring end-tidal carbon dioxide pressure using capnography is a non-invasive method. This study aims to compare end-tidal carbon dioxide values with arterial carbon dioxide pressure in mechanically ventilated patients. The research design is a literature review. Searches were conducted through Scopus, ScienceDirect, ProQuest, and PubMed from 2018 to 2023. The Preferred Reporting Items for Systematic Review and Meta-Analyses flowchart method was used to select articles. The Critical Appraisal Skills Programme was used to assess article quality. Out of 79 articles, nine articles met the criteria. The procedures for collecting end-tidal carbon dioxide pressure and arterial carbon dioxide pressure data varied in terms of instrument types used and the subjects studied. There was no significant difference in carbon dioxide values between the end-tidal carbon dioxide and arterial carbon dioxide pressure methods. The agreement in comparing carbon dioxide values was acceptable. Measuring end-tidal carbon dioxide pressure has the potential to monitor mechanically ventilated patients, reducing the need for invasive monitoring, high costs, and repetitive arterial blood gas analysis.

Noninvasive Ventilation and Exogenous Surfactant in Times of Ever Decreasing Gestational Age: How Do We Make the Most of These Tools?