End-tidal carbon dioxide monitoring in very low birth weight infants: correlation and agreement with arterial carbon dioxide

Prehospital Use of Waveform Capnography in Intubated Neonates

INTRODUCTION

Routine continuous monitoring of endotracheal tube placement with waveform capnography is considered standard of care in the prehospital setting. However, maintaining this standard in neonatal patients remains a challenge due to low tidal volumes that do not tolerate the additional dead space ETCO2 attachments add. Additionally, continuous ETCO2 can increase the risk of ETT dislodgement or kinking because of the weight and size of the capnography attachments relative to the patient and tube size. We hypothesize that there is a gap in care of intubated neonates when compared to adults in the prehospital setting in terms of continuous monitoring of ETT placement.

METHODS

Data were obtained from a single air medical agency. Through a retrospective chart review, records of intubated neonates (<28 days), children (≥28 days-12 years), adolescents (13-18 years), and adults (aged ≥18 years) were analyzed. Records were available from 11/21/13-1/21/22. The number of intubation attempts, whether an intubation was successful, and the use of capnography were recorded in RedCap. Statistical analysis was performed in Microsoft Excel via Chi Square Goodness of Fit Tests.

RESULTS

During the study period, 674 intubation attempts were identified, and 28 charts were excluded due to missing patient age. Continuous waveform ETCO2 monitoring was used on 62%, 94%, 95%, and 97% of successfully intubated neonates, children, adolescents, and adults, respectively. There was a statistically significant difference between use of continuous waveform capnography in adults and neonates (p-value = 0.013). There was also a statistically significant difference between use of continuous waveform capnography in intubated neonates, children, and adolescents (p-value = 0.049).

CONCLUSION

Continuous ETCO2 monitoring is underutilized in intubated neonates compared to children, adolescents, and adults in the prehospital setting in this study population. This suggests a gap in the standard of care provided to neonates. Additional studies are needed to determine if these results are consistent around the industry and if there is a higher rate of undetected tube displacement in neonates who are transported without waveform capnography.

Transcutaneous CO2 Monitoring in Extremely Low Birth Weight Premature Infants

Extremely low birth weight (ELBW) premature infants are particularly susceptible to hypocarbia and hypercarbia, which are associated with brain and lung morbidities. Transcutaneous CO2 (TcCO2) monitoring allows for continuous non-invasive CO2 monitoring during invasive and non-invasive ventilation and is becoming more popular in the NICU. We aimed to evaluate the correlation and agreement between CO2 levels measured by a TcCO2 monitor and blood gas CO2 (bgCO2) among ELBW infants. This was a prospective observational multicenter study. All infants < 1000 g admitted to the participating NICUs during the study period were monitored by a TcCO2 monitor, if available. For each bgCO2 measured, a simultaneous TcCO2 measurement was documented. In total, 1828 pairs of TcCO2-bgCO2 values of 94 infants were collected, with a median (IQR) gestational age of 26.4 (26.0, 28.3) weeks and birth weight of 800 (702, 900) g. A moderate correlation (Pearson: r = 0.64) and good agreement (bias (95% limits of agreement)):(2.9 [-11.8, 17.6] mmHg) were found between the TcCO2 and bgCO2 values in the 25-70 mmHg TcCO2 range. The correlation between the TcCO2 and bgCO2 trends was moderate. CO2 measurements by TcCO2 are in good agreement (bias < 5 mmHg) with bgCO2 among premature infants < 1000 g during the first week of life, regardless of day of life, ventilation mode (invasive/non-invasive), and sampling method (arterial/capillary/venous). However, wide limits of agreement and moderate correlation dictate the use of TcCO2 as a complementary tool to blood gas sampling, to assess CO2 levels and trends in individual patients.

Capnometry during neonatal transport-Mini review

AIM

The aim of this review was to give an overview of available data on end-tidal CO2 (etCO2 ) monitoring, also called capnometry, during neonatal transport.

METHODS

Pubmed/MEDLINE database was searched using research question (capno* OR etCO2 OR detCO2 OR (['end tidal' OR 'end-tidal'] AND [CO2 OR 'carbon dioxide']) AND (neonat* OR infant* OR newborn*) AND transport*). All articles relevant to the topic were reviewed and summarised.

RESULTS

The lack of studies relevant to neonatal transport prompted us to extend the search to capnometry in a neonatal intensive care setting. The published studies are showing conflicting results. The different study populations, technologies used to measure etCO2 , types of etCO2 sampling and the diverse sites of blood gas tests make the data unsuitable for systematic comparison.

CONCLUSION

Further research to obtain more data on capnometry during neonatal transport will be necessary to define precisely under what circumstances can end-tidal monitoring of CO2 be reliably used in neonates during transport and also how to interpret the measured values.

Capnography in newborns under mechanical ventilation and its relationship with the measurement of CO2 in blood samples

INTRODUCTION

Monitoring the partial pressure of CO₂ (PCO₂) in newborns who require ventilation would allow avoiding hypocapnia and hypercapnia. The measurement of end-tidal carbon dioxide (ETCO₂) is an alternative rarely implemented in this population.

OBJECTIVE

To evaluate the relationship between ETCO₂ and PCO₂ in newborns.

METHODS

Cross-sectional study comparing two PCO₂ measurement methods, the conventional one by analysis of blood samples and the one estimated by ETCO₂. The study included hospitalized newborns that required conventional mechanical ventilation. The ETCO₂ was measured with a Tecme GraphNet® neo, a neonatal ventilator with an integrated capnograph, and we obtained the ETCO₂-PCO₂ gradient. We conducted correlation and Bland-Altman plot analyses to estimate the agreement.

RESULTS

A total of 277 samples (ETCO₂ / PCO₂) from 83 newborns were analyzed. The mean values ​​of ETCO₂ and PCO₂ were 41.36mmHg and 42.04mmHg. There was a positive and significant correlation between ETCO₂ and PCO₂ in the overall analysis (r=0.5402; P<.001) and in the analysis of each unit (P<.001). The mean difference was 0.68 mmHg (95% CI, -0.68 to 1.95) and was not significant. We observed a positive systematic error (PCO₂ > ETCO₂) in 2 of the units, and a negative difference in the third (PCO₂ < ETCO₂).

DISCUSSION

The correlation between ETCO and PCO₂ was significant, although the obtained values ​​were not equivalent, with differences ranging from 0.1mmHg and 20mmHg. Likewise, we found systematic errors that differed in sign (positive or negative) between institutions.

Factors affecting the arterial to end-tidal carbon dioxide gradient in ventilated neonates

Objective. To determine factors which influenced the relationship between blood carbon dioxide (pCO₂) and end-tidal carbon dioxide (EtCO₂) values in ventilated, newborn infants. Furthermore, to assess whether pCO₂levels could be predicted from continuous EtCO₂monitoring.Approach. An observational study of routinely monitored newborn infants requiring mechanical ventilation in the first 28 d after birth was undertaken. Infants received standard clinical care. Daily pCO₂and EtCO₂levels were recorded and the difference (gradient: ∆P-EtCO₂) between the pairs were calculated. Ventilatory settings corresponding to the time of each blood gas assessment were noted. End-tidal capnography monitoring was performed using the Microstream sidestream Filterline H set capnograph.Main results. A total of 4697 blood gas results from one hundred and fifty infants were analysed. The infants had a median gestational age of 33.3 (range 22.3-42.0) weeks and birth weight of 1880 (395-5520) grams. Overall, there was moderate correlation between pCO₂and EtCO₂levels (r= 0.65,p< 0.001). The ∆P-EtCO₂for infants born less than 32 weeks of gestation was significantly higher (1.4 kPa) compared to infants born at greater than 32 weeks of gestation (0.8 kPa) (p< 0.001). In infants born at less than 32 completed weeks of gestation, pCO₂levels were independently associated with EtCO₂, day after birth, birthweight and fraction of inspired oxygen (FiO₂) (modelr² = 0.52,p< 0.001).Significance. The results of end-tidal capnography monitoring have the potential to predict blood carbon dioxide values within the neonatal population.

Carbon dioxide monitoring in the newborn infant

Carbon dioxide (CO₂ ) monitoring is vital during mechanical ventilation of newborn infants, as morbidity increases when CO₂ levels are inappropriate. Our aim was to review the uses and limitations of such noninvasive monitoring methods. Colorimetry is primarily utilized during resuscitation to determine whether successful intubation has occurred. False negative and positive results can however lead to delays in detecting tracheal versus esophageal intubation. Transcutaneous carbon dioxide sensors have limited use during resuscitation, but can be utilized to provide continuous trend data during on-going ventilation. End-tidal capnography can provide clinicians with quantitative end-tidal CO₂ (EtCO₂ ) values and a continuous real-time capnogram waveform trace. These devices are becoming more widely accepted for use in the neonatal population as the new devices are lightweight with minimal additional dead space. Nevertheless, they have been reported to have variable accuracy when compared to arterial CO₂ measurements, however, divergence of results may be related to disease severity rather than technological limitations. During resuscitation EtCO₂ can be detected by capnography more rapidly than by colorimetry. Furthermore, capnography can be currently utilized in neonatal research settings to determine the physiological dead space and ventilation inhomogeneity, and thus has potential to be beneficial to clinical care. In conclusion, novel modes of noninvasive carbon dioxide monitoring can be safely and reliably utilized in newborn infants during mechanical ventilation. Future randomized trials should aim to address which device provides the most optimal form of monitoring in different clinical contexts.

End-tidal capnography monitoring in infants ventilated on the neonatal intensive care unit

OBJECTIVE

To assess whether end-tidal capnography (EtCO2) monitoring reduced the magnitude of difference in carbon dioxide (CO2) levels and the number of blood gases in ventilated infants.

STUDY DESIGN

A case-control study of a prospective cohort (n = 36) with capnography monitoring and matched historical controls (n = 36).

RESULT

The infants had a median gestational age of 31.6 weeks. A reduction in the highest CO2 level on day 1 after birth was observed after the introduction of EtCO2 monitoring (p = 0.043). There was also a reduction in the magnitude of difference in CO2 levels on days 1 (p = 0.002) and 4 (p = 0.049) after birth. There was no significant difference in the number of blood gases.

CONCLUSION

Continuous end-tidal capnography monitoring in ventilated infants was associated with a reduction in the degree of the magnitude of difference in CO2 levels and highest level of CO2 on the first day after birth.

Correlation of End-Tidal Carbon Dioxide with Arterial Carbon Dioxide in Mechanically Ventilated Neonates: A Scoping Review

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.

Comparing the novel microstream and the traditional mainstream method of end-tidal CO2 monitoring with respect to PaCO2 as gold standard in intubated critically ill children

The objective of this study was to evaluate a novel microstream method by comparison with PaCO₂ and the more standard mainstream capnometer in intubated pediatric patients. We hypothesized that the novel microstream method would superior compared to the traditional mainstream method in predicting PaCO₂. This was a prospective single-center comparative study. The study was carried out on 174 subjects with a total of 1338 values for each method. Data were collected prospectively from mainstream and microstream capnometer simultaneously and compared with PaCO₂ results. Although both mainstream PetCO₂ (mainPetCO₂) and microstream PetCO₂ (microPetCO₂) were moderately correlated (r = 0.63 and r = 0.68, respectively) with PaCO₂ values, mainPetCO₂ was in better agreement with PaCO₂ in all subjects (bias ± precision values of 3.8 ± 8.9 and 7.3 ± 8.2 mmHg, respectively). In those with severe pulmonary disease, the mainPetCO₂ and microPetCO₂ methods were highly correlated with PaCO₂ (r = 0.80 and r = 0.81, respectively); however, the biases of both methods increased (14.8 ± 9.1 mmHg and 16.2 ± 9.0 mmHg, respectively). In cases with increased physiologic dead space ventilation, the agreement levels of mainPetCO₂ and microPetCO₂ methods became distorted (bias ± precision values of 20.9 ± 11.2 and 25.0 ± 11.8 mm Hg, respectively) even though mainPetCO₂ and microPetCO₂ were highly correlated (r = 0.78 and r = 0.78, respectively). It was found that the novel microstream capnometer method for PetCO₂ measurements provided no superiority to the traditional mainstream method. Both capnometer methods may be useful in predicting the trend of PaCO₂ due to significant correlations with the gold standard measurement in cases with severe pulmonary disease or increased physiological dead space –despite reduced accuracy.

Assessment of sidestream end-tidal capnography in ventilated infants on the neonatal unit

OBJECTIVES

Continuous monitoring of carbon dioxide (CO₂ ) levels can be achieved by capnography. Our aims were to compare the performance of a sidestream capnograph with a low dead space and sampling rate to a mainstream device and evaluate whether its results correlated with arterial/capillary CO₂ levels in infants with different respiratory disease severities.

WORKING HYPOTHESES

End-tidal carbon dioxide (EtCO₂ ) results by sidestream and mainstream capnography would correlate, but the divergence of EtCO₂ and CO₂ results would occur in more severe lung disease.

STUDY DESIGN

Prospective cohort study.

PATIENT-SUBJECT SELECTION

Fifty infants with a median (interquartile range) gestational age of 31.1 (27.1-37.4) weeks and birth weight of 1.37 (0.76-2.95) kg.

METHODOLOGY

Concurrent measurements of EtCO₂ in ventilated infants were made using a new Microstream sidestream device and a mainstream capnograph (gold standard). Results from both devices were compared with arterial or capillary CO₂ levels. The ratio of dead space to tidal volume (Vd/Vt) was calculated to assess respiratory disease severity.

RESULTS

The mean difference between the concurrent measurements of EtCO₂ was -0.54 ± 0.67 kPa (95% agreement levels - 1.86 to 0.77 kPa), the correlation between the two was r = .85 (P < .001). Sidestream capnography results correlated better with partial pressure of CO₂ (PCO₂ ) levels in infants with less (Vd/Vt < 0.35; r²  = .66, P < .001) rather than more severe (Vd/Vt > 0.35; r²  = .33, P = .01) lung disease.

CONCLUSIONS

The sidestream capnography performed similarly to the mainstream capnography. The poorer correlation of EtCO₂ to PCO₂ levels in infants with severe respiratory disease should highlight to clinicians increased ventilation-perfusion mismatch.

Beyond Anesthesia Toxicity: Anesthetic Considerations to Lessen the Risk of Neonatal Neurological Injury

Infants who undergo surgical procedures in the first few months of life are at a higher risk of death or subsequent neurodevelopmental abnormalities. Although the pathogenesis of these outcomes is multifactorial, an understanding of the nature and pathogenesis of brain injury in these infants may assist the anesthesiologist in consideration of their day-to-day practice to minimize such risks. This review will summarize the main types of brain injury in preterm and term infants and their key pathways. In addition, the review will address key potential pathogenic pathways that may be modifiable including intraoperative hypotension, hypocapnia, hyperoxia or hypoxia, hypoglycemia, and hyperthermia. Each of these conditions may increase the risk of perioperative neurological injury, but their long-term ramifications are unclear.

Comparison of mainstream (Capnostat 5) and two low-flow sidestream capnometers (VM-2500-S and Capnostream) in spontaneously breathing rabbits anesthetized with a Bain coaxial breathing system

OBJECTIVE

To evaluate agreement with PaCO₂ of two low sampling rate sidestream capnometers and a mainstream capnometer in rabbits and the effect of using high fresh gas flow from a Bain coaxial breathing system.

STUDY DESIGN

Prospective, crossover study.

ANIMALS

A total of 10 New Zealand White rabbits weighing 3.4 ± 0.3 kg [mean ± standard deviation (SD)].

METHODS

Two sidestream analyzers (Viamed VM-2500-S and Capnostream 35) with a sampling rate of 50 mL minute^-1 and a mainstream capnometer (Capnostat 5) were tested. All capnometers used infrared spectroscopy and advanced microprocessor technology. Rabbits were anesthetized and intubated with noncuffed endotracheal tubes of 3 mm internal diameter and adequate seal. A sidestream sampling adapter or the mainstream capnometer was attached to the endotracheal tube and connected to a Bain coaxial breathing system. Oxygen (1.5 L minute^-1) delivered sevoflurane to maintain anesthesia. An auricular artery catheter allowed blood sampling for PaCO₂ analysis corrected to rectal temperature. Inspired and end-tidal carbon dioxide (Pe'CO₂) measurements were recorded during blood sample withdrawal. From each rabbit, 10 paired PaCO₂/Pe'CO₂ measurements were obtained. Each rabbit was recovered from anesthesia and was anesthetized again with an alternate capnometer after 1 week. Data were analyzed using Bland-Altman and two-way anova for repeated measures.

RESULTS

Analysis included 100 paired samples. Negative bias reflects underestimation of PaCO₂. Bland-Altman mean (±1.95 SD) was -16.7 (-35.2 to 1.8) mmHg for Capnostat 5, -27.9 (-48.6 to -7.2) mmHg for Viamed, and -18.1 (-34.3 to -1.9) mmHg for Capnostream. Viamed PaCO₂-Pe'CO₂ gradient was greater than other two capnometers.

CONCLUSIONS

All three capnometers underestimated PaCO₂. Capnostat 5 and Capnostream performed similarly.

CLINICAL RELEVANCE

These capnometers underestimated PaCO₂ in spontaneously breathing rabbits anesthetized using a Bain coaxial breathing system with high fresh gas flows.

Transcutaneous CO2 versus end-tidal CO2 in neonates and infants undergoing surgery: a prospective study

Aim: End-tidal CO2 (EtCO2) is the standard in operative care along with pulse oximetry for ventilation assessment. It is known to be less accurate in the infant population than in adults. Many neonatal intensive care units (NICU) have converted to utilizing transcutaneous CO2 (tcPCO2) monitoring. This study aimed to compare perioperative EtCO2 to tcPCO2 in the pediatric perioperative population specifically below 10 kg, which encompasses neonates and some infants. Methods: After IRB approval and parental written informed consent, we enrolled neonates and infants weighing less than 10 kg, who were scheduled for elective surgery with endotracheal tube under general anesthesia. PCO2 was monitored with EtCO2 and with tcPCO2. Venous blood gas (PvCO2) samples were drawn at the end of the anesthetic. We calculated a mean difference of EtCO2 minus PvCO2 (Delta EtCO2), and tcPCO2 minus PvCO2 (Delta tcPCO2) from end-of-case measurements. The mean differences in the NICU and non-NICU patients were compared by t-tests and Bland-Altman analysis. Results: Median age was 10.9 weeks, and median weight was 4.4 kg. NICU (n=6) and non-NICU (n=14) patients did not differ in PvCO2. Relative to the PvCO2, the Delta EtCO2 was much greater in the NICU compared to the non-NICU patients (-28.1 versus -9.8, t=3.912, 18 df, P=0.001). Delta tcPCO2 was close to zero in both groups. Although both measures obtained simultaneously in the same patients agreed moderately with each other (r =0.444, 18 df, P=0.05), Bland-Altman plots indicated that the mean difference (bias) in EtCO2 measurements differed significantly from zero (P<0.05). Conclusions: EtCO2 underestimates PvCO2 values in neonates and infants under general anesthesia. TcPCO2 closely approximates venous blood gas values, in both the NICU and non-NICU samples. We, therefore, conclude that tcPCO2 is a more accurate measure of operative PvCO2 in infants, especially in NICU patients.

Effect of corrective or palliative procedures on arterial to end-tidal carbon dioxide pressure difference in pediatric cardiac surgery

BACKGROUND

The normal small difference (3-5 mmHg) between arterial (partial pressure of carbon dioxide [PaCO₂]) and end-tidal carbon dioxide pressure (ETPCO₂) increases in children with congenital heart disease. The present study was conducted to evaluate the effect of corrective or palliative cardiac surgery on this difference (known as DPCO2).

PATIENTS AND METHODS

In a prospective study, 200 children (aged <12 years old) candidate for corrective or palliative cardiac surgery were studied. Using arterial blood gas measurement and simultaneous capnography, DPCO₂ was calculated at various intra- and postoperative periods. DPCO₂ values were compared within and between corrective or palliative procedures.

RESULTS

Corrective and palliative procedures were carried out on 154 and 46 patients, respectively. Initial DPCO₂ was higher than normal values in corrective or palliative procedures (15.50 ± 13.1 and 10.75 ± 9.1 mmHg, respectively). DPCO₂ was higher in patients who underwent palliative procedure, except early after procedure. The procedure did not have any effect on the final DPCO₂ in palliative group. Although DPCO₂ decrease was significant in the corrective group, it did not return to normal values. Operation time was longer, and the need to inotropic support was higher in corrective procedures; however, longer periods of ventilatory support were needed in the palliative group. Complication rate and Intensive Care Unit stay time were the same in two operation types.

CONCLUSIONS

DPCO₂ did not change after palliative cardiac procedures. DPCO₂ decreased after corrective procedures; however, it did not return to normal values at early postoperative period. Thus, DPCO₂ may not have any clinical value in monitoring the quality of corrective or palliative procedures.

Poor performance of main-stream capnography in newborn infants during general anesthesia

BACKGROUND

Endtidal (ET) measurement of carbon dioxide is well established for intraoperative respiratory monitoring of adults and children, but the method's accuracy for intraoperative use in small newborn infants has been less extensively investigated.

AIMS

The aim of this study was to compare carbon dioxide from ET measurements with arterialized capillary blood samples in newborn infants during general anesthesia and surgery.

METHODS

Endtidal carbon dioxide was continuously measured during anesthesia and surgery and compared with simultaneous blood gas analyses obtained from capillary blood samples. Fifty-nine sample sets of ET to blood gas carbon dioxide were obtained from 23 prospectively enrolled infants with a gestational age of 23-41 weeks and a birth weight of 670-4110 g.

RESULTS

Endtidal levels of carbon dioxide were considerably lower in all sample sets and only 4/23 individual ET-blood gas sample pairs differed <7.5 mm Hg (1 kPa). Bland-Altman analysis indicated a poor agreement with a bias of -13 ± 7 mm Hg and a precision of ±14 mm Hg. The performance of ET measurements was particularly poor in infants weighing below 2.5 kg, in infants in need of respiratory support prior to anesthesia, and when the true (blood gas) carbon dioxide level was high, above 45 mm Hg.

CONCLUSION

Main-stream capnography during anesthesia and surgery correlated poorly to blood gas values in small and/or respiratory compromised infants. We conclude that caution should be exercised when relying solely on ET measurements to guide mechanical ventilation in the OR.

End-tidal carbon dioxide measurement in preterm infants with low birth weight

Objective

There 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 (V_D/V_T) on the correlation between PetCO₂ and arterial carbon dioxide pressure (PaCO₂) in ventilated preterm infants with respiratory distress syndrome (RDS).

Methods

We 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.

Results

One-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 V_D/V_T in the post-surfactant treatment group when compared to the pre-surfactant treatment group (P = 0.003).

Conclusions

V_D/V_T decreased significantly after surfactant therapy and the correlation between PetCO₂ and PaCO₂ was higher after surfactant therapy in preterm infants with RDS.

Application of end-tidal carbon dioxide monitoring via distal gas samples in ventilated neonates

BACKGROUND

Previous research has suggested correlations between the end-tidal partial pressure of carbon dioxide (P_ETCO₂) and the partial pressure of arterial carbon dioxide (PaCO₂) in mechanically ventilated patients, but both the relationship between P_ETCO₂ and PaCO₂ and whether P_ETCO₂ accurately reflects PaCO₂ in neonates and infants are still controversial. This study evaluated remote sampling of P_ETCO₂ via an epidural catheter within an endotracheal tube to determine the procedure's clinical safety and efficacy in the perioperative management of neonates.

METHODS

Abdominal surgery was performed under general anesthesia in 86 full-term newborns (age 1-30 days, weight 2.55-4.0 kg, American Society of Anesthesiologists class I or II). The infants were divided into 2 groups (n = 43 each), and carbon dioxide (CO₂) gas samples were collected either from the conventional position (the proximal end) or a modified position (the distal end) of the epidural catheter.

RESULTS

The P_ETCO₂ measured with the new method was significantly higher than that measured with the traditional method, and the difference between P_ETCO₂ and PaCO₂ was also reduced. The accuracy of P_ETCO₂ measured increased from 78.7% to 91.5% when the modified sampling method was used. The moderate correlation between P_ETCO₂ and PaCO₂ by traditional measurement was 0.596, which significantly increased to 0.960 in the modified sampling group. Thus, the P_ETCO₂ value was closer to that of PaCO₂.

CONCLUSION

P_ETCO₂ detected via modified carbon dioxide monitoring had a better accuracy and correlation with PaCO₂ in neonates.

Carbon Dioxide Fluctuations Are Associated with Changes in Cerebral Oxygenation and Electrical Activity in Infants Born Preterm

OBJECTIVES

To evaluate the effects of acute arterial carbon dioxide partial pressure changes on cerebral oxygenation and electrical activity in infants born preterm.

STUDY DESIGN

This retrospective observational study included ventilated infants born preterm with acute fluctuations of continuous end-tidal CO₂ (etCO₂) as a surrogate marker for arterial carbon dioxide partial pressure, during the first 72 hours of life. Regional cerebral oxygen saturation and fractional tissue oxygen extraction were monitored with near-infrared spectroscopy. Brain activity was monitored with 2-channel electroencephalography. Spontaneous activity transients (SATs) rate (SATs/minute) and interval between SATs (in seconds) were calculated. Ten-minute periods were selected for analysis: before, during, and after etCO₂ fluctuations of ≥5  mm Hg.

RESULTS

Thirty-eight patients (mean ± SD gestational age of 29 ± 1.8 weeks) were included, with 60 episodes of etCO₂ increase and 70 episodes of etCO₂ decrease. During etCO₂ increases, brain oxygenation increased (regional cerebral oxygen saturation increased, fractional tissue oxygen extraction decreased; P < .01) and electrical activity decreased (SATs/minute decreased, interval between SATs increased; P < .01). All measures recovered when etCO₂ returned to baseline. During etCO₂ decreases, brain oxygenation decreased (regional cerebral oxygen saturation decreased, fractional tissue oxygen extraction decreased; P < .01) and brain activity increased (SATs/minute increased, P < .05), also with recovery after return of etCO₂ to baseline.

CONCLUSION

An acute increase in etCO₂ is associated with increased cerebral oxygenation and decreased brain activity, whereas an acute decrease is associated with decreased cerebral oxygenation and slightly increased brain activity. Combining continuous CO₂ monitoring with near-infrared spectroscopy may enable the detection of otherwise undetected fluctuations in arterial carbon dioxide partial pressure that may be harmful to the neonatal brain.

Transcutaneous PCO2 Monitoring in Newborn Infants During General Anesthesia Is Technically Feasible

Published ahead of print July 26, 2016.

BACKGROUND:

Transcutaneous (TC) measurement of Pco₂ (TC Pco₂) is a well-established method to monitor assisted ventilation in neonatal intensive care, but its use in the operating room is limited, and the data regarding its performance during general anesthesia of the newborn are lacking. The aim of this study is to evaluate the performance of continuous TC Pco₂ monitoring during general anesthesia in newborn infants.

METHODS:

Infants (n = 25) with a gestational age of 23 to 41 weeks and a birth weight of 548 to 4114 g were prospectively enrolled. During general anesthesia and surgery, TC Pco₂ was measured continuously and recorded at 1-minute intervals. Five-minute mean values were compared with simultaneously obtained blood gas (BG) analyses of Pco₂. Only the first paired TC and BG samples were used in this analysis. We defined precision as 2.1 times the standard deviation of the difference of the 2 samples. P < .01 was considered statistically significant.

RESULTS:

We obtained samples from 25 infants. The difference between TC and BG was 0.3 ± 0.7 kPa (mean ± standard deviation) giving a precision of 1.47 kPa. Nineteen of twenty-five (76%) sample pairs displayed a difference of <1 kPa (99% confidence interval, 48%–92%, P = .016). The difference in paired samples was similar for different gestational and postnatal ages and did not appear to be affected by electrocautery.

CONCLUSIONS:

In this small study, we did not demonstrate that TC CO₂ monitoring was accurate at P < .01. This partly reflects the small size of the study, resulting in wide 99% confidence bounds.

Cardiorespiratory events in preterm infants: etiology and monitoring technologies

Every year, an estimated 15 million infants are born prematurely (<37 weeks gestation) with premature birth rates ranging from 5 to 18% across 184 countries. Although there are a multitude of reasons for this high rate of preterm birth, once birth occurs, a major challenge of infant care includes the stabilization of respiration and oxygenation. Clinical care of this vulnerable infant population continues to improve, yet there are major areas that have yet to be resolved including the identification of optimal respiratory support modalities and oxygen saturation targets, and reduction of associated short- and long-term morbidities. As intermittent hypoxemia is a consequence of immature respiratory control and resultant apnea superimposed upon an immature lung, improvements in clinical care must include a thorough knowledge of premature lung development and pathophysiology that is unique to premature birth. In Part 1 of a two-part review, we summarize early lung development and diagnostic methods for cardiorespiratory monitoring.

Innovations and controversies in the monitoring of pediatric patients in the ICU

In recent years, the number of monitoring options for ICU clinicians has continued to proliferate, but there has been limited information regarding their value in shortening length of stay, averting complications including death, or improving functional outcomes. However, innovative new approaches hold the promise of integrating data sets to help clinicians avert complications and to detect evolving organ dysfunction earlier.

Monitoring Oxygenation and Gas Exchange in Neonatal Intensive Care Units: Current Practice in the Netherlands

BACKGROUND

Although recommendations in oxygenation and gas exchange monitoring in the neonatal intensive care unit (NICU) are available, little is known of the current practice.

AIM

To evaluate the current practice in oxygenation and gas exchange monitoring of the NICUs in the Netherlands.

METHODS

An online survey-based questionnaire concerning preferences and current practice of monitoring oxygenation and gas exchange was sent out to all 107 neonatal staff members (neonatologists, neonatal fellows, and physician assistants) of the 10 NICUs in the Netherlands.

RESULTS

The response rate was 42%. Pulse oximetry (PO), partial pressure of oxygen in arterial blood gas (paO2), and oxygen saturation in arterial blood gas (saO2) was used by, respectively, 100, 80, and 27% of the staff members for monitoring oxygenation. Of all staff members, 76% considered PO as the best parameter for monitoring oxygenation, 22% paO2, and 2% saO2. Blood gas, transcutaneous gas monitoring, endotracheal gas monitoring, and near-infrared spectroscopy was used by, respectively, 100, 82, 40, and 18% of the staff members for monitoring gas exchange. During endotracheal ventilation, 67% of the caregivers would exclusively accept arterial blood gas for gas exchange monitoring. In contrast, during non-invasive ventilation, 68% of the caregivers did not prefer arterial or capillary blood gas (CBG). CBG is found reliable in infants with warm extremities by 76% of the caregivers. Venous blood gas would be accepted by 60% of the caregivers, independent of the mode of respiratory support, and only when venous blood sample was needed for other reasons.

CONCLUSION

This survey identified a wide variation in preference in monitoring oxygenation and gas exchange monitoring among Dutch neonatal staff members.

Correlation of end tidal and arterial carbon dioxide levels in critically Ill neonates and children

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.

Beyond survival; influences of blood pressure, cerebral perfusion and anesthesia on neurodevelopment

Neonates have a higher perioperative mortality risk largely due to the degree of prior illness of the infants, the complexity of their surgeries, and infant physiology. It is important to consider contributing anesthetic factors during the perioperative period that may affect cerebral perfusion and neurocognitive outcome, such as alterations in hemodynamics and ventilation. Limitations of blood pressure as a marker for cerebral perfusion are discussed, as well as the effect of hypocapnia on the brain.

Apnea of prematurity--perfect storm

With increased survival of preterm infants as young as 23 weeks gestation, maintaining adequate respiration and corresponding oxygenation represents a clinical challenge in this unique patient cohort. Respiratory instability characterized by apnea and periodic breathing occurs in premature infants because of immature development of the respiratory network. While short respiratory pauses and apnea may be of minimal consequence if oxygenation is maintained, they can be problematic if accompanied by chronic intermittent hypoxemia. Underdevelopment of the lung and the resultant lung injury that occurs in this population concurrent with respiratory instability creates the perfect storm leading to frequent episodes of profound and recurrent hypoxemia. Chronic intermittent hypoxemia contributes to the immediate and long term co-morbidities that occur in this population. In this review we discuss the pathophysiology leading to the perfect storm, diagnostic assessment of breathing instability in this unique population and therapeutic interventions that aim to stabilize breathing without contributing to tissue injury.

High-flow nasal cannula oxygen for bronchiolitis in a pediatric ward: a pilot study

High-flow nasal cannula (HFNC) is a widely used ventilatory support in children with bronchiolitis in the intensive care setting. No data is available on HFNC use in the general pediatric ward. The aim of this study was to evaluate the feasibility of HFNC oxygen therapy in infants hospitalized in a pediatric ward for moderate-severe bronchiolitis and to assess the changes in ventilatory parameters before and after starting HFNC support. This prospective observational pilot study was carried out during the bronchiolitis season 2011-2012 in a pediatric tertiary care academic center in Italy. Interruptions of HFNC therapy and possible side effects or escalation to other forms of respiratory support were recorded. Oxygen saturation (SpO2), end-tidal carbon dioxide (ETCO2), and respiratory rate (RR), measured for a baseline period of 1 h before and at specific time intervals in 48 h after the start of HFNC were recorded. Twenty-seven infants were included (median age 1.3 months; absolute range 0.3-8.5). No adverse events, no premature HFNC therapy termination, and no escalation to other forms of respiratory support were recorded. Median SpO2 significantly increased by 1-2 points after changing from standard oxygen to HFNC (p <0.001). Median ETCO2 and RR rapidly decreased by 6-8 mmHg and 13-20 breaths per minute, respectively, in the first 3 h of HFNC therapy (p <0.001) and remained steady thereafter.

CONCLUSIONS

Use of HFNC for oxygen administration is feasible for infants with moderate-severe bronchiolitis in a general pediatric ward. In these children, HFNC therapy improves oxygen saturation levels and seems to be associated with a decrease in both ETCO2 and RR.