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

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.

Comparison of two sizes of GlideScope® blades in tracheal intubation of infants: a randomised clinicaltrial☆

BACKGROUND

The appropriate size of GlideScope® blade for tracheal intubation in neonates and premature infants has not been established. We evaluated the impact of the size of the GlideScope® blade on the time taken for intubation in infants weighing 2.5-3.6 kg.

METHODS

Sixty infants weighing 2.5-3.6 kg were randomly assigned to use of the size 1 blade (n=30) or the size 2 blade (n=30). The primary outcome was the time taken to intubate. Components related to the laryngoscopic view which could affect the duration of the intubating process were also analysed.

RESULTS

The time required for tracheal intubation was shorter with the size 2 blade than with the size 1 blade (16 [14-20] s vs 22 [18-25] s, P=0.002; median difference=-5; 95% confidence interval, -7 to -2). The rate at which the tip of the tracheal tube was located at the centre of the laryngeal inlet was higher with the size 2 blade than with the size 1 blade (83% vs 40%, P<0.001). Correlation analysis indicated that the time required to find the tip of the tube was related to how far the lower border of the arytenoid cartilages was located from the mid-horizontal line of the monitor (r=0.28, P=0.033).

CONCLUSION

Use of the size 2 blade significantly reduced the time required to intubate the trachea, compared with the size 1 GlideScope® blade in infants.

CLINICAL TRIAL REGISTRATION

KCT 0003867.

Non-invasive carbon dioxide monitoring in neonates: methods, benefits, and pitfalls

Wide fluctuations in partial pressure of carbon dioxide (PaCO2) can potentially be associated with neurological and lung injury in neonates. Blood gas measurement is the gold standard for assessing gas exchange but is intermittent, invasive, and contributes to iatrogenic blood loss. Non-invasive carbon dioxide (CO2) monitoring has become ubiquitous in anesthesia and critical care and is being increasingly used in neonates. Two common methods of non-invasive CO2 monitoring are end-tidal and transcutaneous. A colorimetric CO2 detector (a modified end-tidal CO2 detector) is recommended by the International Liaison Committee on Resuscitation (ILCOR) and the American Academy of Pediatrics to confirm endotracheal tube placement. Continuous CO2 monitoring is helpful in trending PaCO2 in critically ill neonates on respiratory support and can potentially lead to early detection and minimization of fluctuations in PaCO2. This review includes a description of the various types of CO2 monitoring and their applications, benefits, and limitations in neonates.

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.

Carbon dioxide monitoring in children-A narrative review of physiology, value, and pitfalls in clinical practice

Continuous capnography has been recognised as an essential monitoring device in all anesthetized patients, despite which airway device is in use, regardless of their location, as a measure to improve patient safety. Capnography is the non-invasive measurement of a sample of the exhaled carbon dioxide which has multiple clinical uses including as a method to confirm placement of a tracheal tube and/or to assess ventilation, perfusion and metabolism. Notably, capnography is used during routine paediatric anesthesia to assess ventilation and as a surrogate measure for arterial carbon dioxide pressure. The inaccuracies associated with these surrogate measures need to be considered to inform improved ventilation management of infants and children. This review highlights some major principles to understand the carbon dioxide elimination, the physiology of paediatric capnography, the clinical application and the limitations of capnography during anesthesia for neonates, infants and small children.

Comparison of Simultaneous Capillary Blood Gases and End-Tidal Carbon Dioxide in Mechanically Ventilated Pediatric Patients with Acute Respiratory Failure

In the follow-up of ventilation, invasive blood gas analysis and noninvasive monitoring of end-tidal carbon dioxide (ETCO ₂ ) are used. We aimed to investigate the relationship between capillary partial pressure of carbon dioxide (PcCO ₂ ) levels and ETCO ₂ and also to investigate ETCO ₂ 's predictive feature of PcCO ₂ levels. This study included 28 female and 30 male pediatric patients; 28 patients were type-1 respiratory failure (RF), 16 patients were acute respiratory distress syndrome, and 14 patients were type-2 RF. Our results showed a significant correlation between ETCO ₂ and PcCO ₂ . Although the strength of the correlation was weak throughout the measurements, the strength of this correlation increased significantly in type-2 RF.

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.

Comparison of GlideScope Video Laryngoscopy and Direct Laryngoscopy for Tracheal Intubation in Neonates

BACKGROUND

GlideScope video laryngoscope (GS) has been widely used to facilitate tracheal intubation in adults and pediatric patients because it can improve glottic view. Several investigations performed in pediatric patients have shown that GS provides a better view of the glottis than direct laryngoscope (DL). However, to date, there are no studies assessing the use of GS in neonates. Therefore, we conducted a prospective study to compare time to intubate (TTI) when either GS or DL was used for endotracheal intubation in neonates.

METHODS

Seventy neonates (American Society of Anesthesiologists physical status I and II, scheduled to undergo elective surgery under general anesthesia) were randomized to GS group (n = 35) and DL group (n = 35). The primary outcome variable of the study was TTI. As secondary outcomes, success rate of first intubation attempt of all neonates, intubation attempts, and adverse events were also evaluated. The glottic views (depicted by Cormack and Lehane [C&L] grades) obtained with GS and DL were compared.

RESULTS

There were no significant differences in TTIs of neonates with all C&L grades (95% CI, -7.36 to 4.44). There was also no difference in the subgroups of neonates with C&L grades I and II (n = 30 each; 95% CI, -0.51 to 5.04). However, GS significantly shortened the TTIs of neonates with C&L grades III and IV compared to DL (n = 5 each group; 95% CI, 4.94-46.67). GS improved the glottic view as compared to DL. Although the total tracheal intubation attempts in the GS group was fewer than that in the DL group (36 vs 41), there was no significant difference (P = .19).

CONCLUSIONS

GS use did not decrease the TTI of all neonates and neonates with C&L grades I and II as compared to DL use; however, GS significantly decreased the TTI of neonates with C&L grades III and IV. Additionally, GS use provided improved glottic views.