Continuous End-tidal Carbon Dioxide Monitoring Research Articles

A Pilot Study of End-Tidal Carbon Dioxide in Prediction of Inhospital Cardiac Arrests.

Objectives:A validated means to predict inhospital cardiac arrest is lacking. The purpose of this study was to evaluate the changes in end-tidal carbon dioxide, as it correlates with the progression to inhospital cardiac arrest in ICU patients.Design, Setting, and Patients:Single-center, retrospective cohort study of mechanically ventilated ICU patients (age > 18 yr old) having inhospital cardiac arrest with advanced cardiac life support and continuous end-tidal carbon dioxide monitoring at a single academic center from 2014 to 2017. Demographics, clinical variables, and outcomes were collected. End-tidal carbon dioxide was collected from 5 to 2,880 minutes before inhospital cardiac arrest. Data were analyzed using descriptive statistics, and model estimates were generated using a repeated-measures categorical model with restricted maximum likelihood estimation and fully specified (autoregressive) covariance to assess the effect of time on changes in end-tidal carbon dioxide.Measurements and Main Results:A total of 788 patients were identified and 104 met inclusion criteria, where 62% were male with an average age of 58.5 years. Seventy-four percent required vasopressors and 72% experienced pulseless electrical activity. Mean end-tidal carbon dioxide 5 minutes prior to inhospital cardiac arrest was significantly lower than all evaluated time points except 180 minutes (p < 0.05). One patient survived to hospital discharge. In multivariate logistic regression modeling for return of spontaneous circulation, a greater change in the prearrest end-tidal carbon dioxide maximum to prearrest end-tidal carbon dioxide minimum was associated with a decreased likelihood of return of spontaneous circulation (odds ratio 0.903; 95% CI, 0.832–0.979; p = 0.014). Additionally, a change from prearrest end-tidal carbon dioxide maximum to prearrest end-tidal carbon dioxide minimum greater than 17 mm Hg was associated with a decreased likelihood of return of spontaneous circulation and odds ratio 0.150; 95% CI, 0.036–0.66; p = 0.012).Conclusions:Mean end-tidal carbon dioxide is significantly lower immediately before inhospital cardiac arrest. The statistical and clinical significance of end-tidal carbon dioxide may highlight its utility for predicting inhospital cardiac arrest in ICU patients. Comparison analysis and modeling explorations in a larger cohort are needed.

Continuous End-Tidal Carbon Dioxide Monitoring during Resuscitation of Asphyxiated Term Lambs

Background: The Neonatal Resuscitation Program (NRP) recommends close monitoring of oxygenation during the resuscitation of newborns using a pulse oximeter. However, there are no guidelines for monitoring carbon dioxide (CO₂) to assess ventilation. Considering that cerebral blood flow (CBF) correlates directly with PaCO₂, continuous capnography monitoring of end-tidal CO₂ (ETCO₂) may limit fluctuations in PaCO₂ and, therefore, CBF during resuscitation of asphyxiated infants. Objective: To evaluate whether continuous monitoring of ETCO₂ with capnography during resuscitation of asphyxiated term lambs with meconium aspiration will prevent fluctuations in PaCO₂ and carotid arterial blood flow (CABF). Methods: Fifty-four asphyxiated term lambs with meconium aspiration syndrome were mechanically ventilated from birth to 60 min of age. Ventilatory parameters were adjusted based on clinical observation (chest excursion) and frequent arterial blood gas analysis in 24 lambs (control group) and 30 lambs (capnography group) received additional continuous ETCO₂ monitoring. Left CABF was monitored. We aimed to maintain PaCO₂ between 35 and 50 mm Hg and ETCO₂ between 30 and 45 mm Hg. Results: There was a significant correlation between ETCO₂ and PaCO₂ (R = 0.7, p < 0.001), between PaCO₂ and carotid flow (R = 0.52, p < 0.001) and between ETCO₂ and carotid flow (R = 0.5, p < 0.001). PaCO₂ and CABF during the first 60 min of age showed significantly higher fluctuation in the control group compared to the capnography group. Conclusion: Continuous monitoring of ETCO₂ using capnography with mechanical ventilation during and after resuscitation in asphyxiated term lambs with meconium aspiration limits fluctuations in PaCO₂ and CABF and may potentially limit brain injury.

In Reply

We thank Drs. Youngblood and Sondergaard for their letters regarding our recently published article.1We agree with Dr. Youngblood1 that standard monitoring already provides substantial information about our patients’ hemodynamic status. Today, pulse pressure variation (PPV) and its corresponding noninvasive parameters are easily available and used in clinical practice.2 In recent years, PPV analysis algorithms have been integrated into different standard monitoring systems,3 and PPV can be reliably assessed on a noninvasive basis by plethysmography.4 Thus, standard monitoring evolves, and today PPV can be considered a standard hemodynamic parameter for a larger population of patients who require perioperative invasive blood pressure monitoring with an arterial line. When no arterial line is required, pulse oximetry devices, which provide the respective functional hemodynamic parameters, can be applied to assess and predict fluid responsiveness. Clearly, continuous end-tidal carbon dioxide monitoring may further support clinical decision making—but still this requires validation in large perioperative clinical studies. In addition, one has to keep in mind that the changes in end-tidal carbon dioxide, induced by a passive leg raising, cannot always be assessed during surgery.We read with interest Dr. Sondergaard’s acerbic letter regarding our article; we thank him for the querulous interest he has shown in our work. Neither our results nor our discussion demonstrate that the PPV should replace cardiac output (CO) measurements. Dr. Sondergaard’s reference of our work when making this claim suggests that he is less familiar with our results.We do demonstrate that when estimating CO trends, volume expansion-induced changes in PPV is superior to standard measures of arterial pressure.1,5 PPV is interesting because it identifies patients who will benefit from fluid loading and volume expansion-induced changes in PPV allows for ongoing assessment of fluid-loading efficacy. This provides the clinician with important information which then allows for CO optimization.Does an increased CO, as a result of fluid loading, result in improved postoperative outcomes? Dr. Sondergaard will be disappointed when we affirm that we do not have the answer to this question. He may be even more disappointed when we affirm that the answer to this question can probably not be framed in his favored “YES/NO” format.CO is only one of the components of oxygen delivery, and maximizing CO, through fluid administration, does not equate to optimization of oxygen delivery. Fluid loading always causes hemodilution, and hemoglobin concentration plays a key role in oxygen delivery. It is therefore possible that increasing CO, by administering a large fluid load, may actually decrease oxygen delivery. Oxygen delivery is the true parameter to optimize, but it remains difficult to measure and several parameters should be simultaneously optimized to achieve ideal oxygen delivery. PPV and volume expansion-induced changes in PPV are only two of the tools, which may be used to achieve this goal. Using them in isolation may be appropriate in some clinical settings, but it will always remain suboptimal.Our aim in conducting this study was to explore the predictive performance of PPV under ideal conditions. As a result, we did not record the number of patients who were not selected because of atrial fibrillation.May we offer a more balanced and less jejune set of conclusions than those purportedly “obvious” conclusions drawn by Dr. Sondergaard?NO; CO measurements alone is not sufficient for optimization of oxygen delivery. Fluid loading impacts hemoglobin concentration, and neither volume expansion-induced changes in PPV nor direct CO measurements reliably reflect this.NO; because there is no strong and definitive evidence to suggest that “validated” and calibrated dilution methods with continuous, updated arterial curve–based calculation of CO impact on postoperative outcomes, we do not have to use them (“…no monitoring tool, no matter how accurate, by itself has improved patient outcome.”)6NO; we do not find ourselves compelled to adopt cardiovascular models from giants such as Guyton or Dr. Sondergaard. Eminence is rarely, if ever, a substitute for evidence.YES, key opinion holders in the European intensive care community should be very cautious about promoting any device or system that has not clearly demonstrated its ability to improve postoperative outcomes.Having matured beyond Dr. Sondergaard’s preoccupation with dreams of the conceptualization and intellectualization of endeavors past explored, we have actually evaluated PVV to understand its abilities and limitations. Although PPV informs clinicians on how fluid loading impacts on CO, there is a common misconception that fluid loading is required when PPV is high—this requires correcting.PPV requires engagement, interpretation, and judgment. For this reason, we have developed the grey zone concept, which we offer to Dr. Sondergaard in the hope that he would evaluate it empirically in a clinical study.

Continuous end-tidal carbon dioxide monitoring in pediatric intensive care units

PurposeEnd-tidal carbon dioxide (ETCO2) monitoring has a variety of clinical applications in critically ill pediatric patients. This study was designed to explore the current availability and utilization patterns for continuous ETCO2 monitoring in pediatric intensive care units. MethodsA Web-based survey was distributed to directors of all accredited pediatric critical care fellowship programs in the United States. ResultsSixty-six percent of directors completed this survey. One hundred percent of directors had access to ETCO2 monitoring for intubated patients and 57% for nonintubated patients. Eighty-three percent of respondents used ETCO2 monitoring “always” or “often” for endotracheal tube confirmation. Fifty percent of respondents used ETCO2 monitoring “always” or “often” for cardiopulmonary resuscitation, 38% for moderate sedation, and 5% for acid-base disturbances. All respondents who used ETCO2 monitoring felt that it was easy to use. The most common reason for not using ETCO2 monitoring was lack of availability (75%). ConclusionsEnd-tidal carbon dioxide monitoring is widely available and used for intubated patients. However, it could be applied more frequently in other clinical situations in pediatric intensive care units.

Current Utilization of Continuous End-Tidal Carbon Dioxide Monitoring in Pediatric Emergency Departments

End-tidal carbon dioxide (ETCO2) monitoring has numerous clinical applications in the emergency setting. This study was designed to explore the current availability and utilization patterns for continuous ETCO2 monitoring in pediatric emergency departments. A Web-based survey was distributed to directors of all accredited pediatric emergency medicine fellowship programs in the United States and Canada. Eighty-one percent of directors completed this survey. Eighty-eight percent had access to ETCO2 monitoring for intubated patients and 53% for nonintubated patients. Seventy-nine percent of respondents used ETCO2 monitoring "always" or "often" for endotracheal tube confirmation. Only 20% of respondents used ETCO2 monitoring "always" or "often" for moderate sedation, 16% for trauma, and 6% for acid-base disturbances. One hundred percent of respondents who used ETCO2 monitoring felt that it was easy to use. The most common reason for not using ETCO2 monitoring was lack of equipment (65%). ETCO2 monitoring is widely available, yet underutilized, for spontaneously breathing patients in pediatric emergency departments.

Continuous end-tidal carbon dioxide monitoring for confirmation of endotracheal tube placement is neither widely available nor consistently applied by emergency physicians

Objectives: To determine the availability of end-tidal CO2 measurement in confirmation of endotracheal tube placement in the non-arrest patient, and to assess its use in academic and non-academic emergency departments....

The Effectiveness of Out-of-Hospital Use of Continuous End-Tidal Carbon Dioxide Monitoring on the Rate of Unrecognized Misplaced Intubation Within a Regional Emergency Medical Services System

We evaluate the association between out-of-hospital use of continuous end-tidal carbon dioxide (ETCO2) monitoring and unrecognized misplaced intubations within a regional emergency medical services (EMS) system. This was a prospective, observational study, conducted during a 10-month period, on all patients arriving at a regional Level I trauma center emergency department who underwent out-of-hospital endotracheal intubation. The regional EMS system that serves the trauma service area is composed of multiple countywide systems containing numerous EMS agencies. Some of the EMS agencies had independently implemented continuous ETCO2 monitoring before the start of the study. The main outcome measure was the unrecognized misplaced intubation rate with and without use of continuous ETCO2 monitoring. Two hundred forty-eight patients received out-of-hospital airway management, of whom 153 received intubation. Of the 153 patients, 93 (61%) had continuous ETCO2 monitoring, and 60 (39%) did not. Forty-nine (32%) were medical patients, 104 (68%) were trauma patients, and 51 (33%) were in cardiac arrest. The overall incidence of unrecognized misplaced intubations was 9%. The rate of unrecognized misplaced intubations in the group for whom continuous ETCO2 monitoring was used was zero, and the rate in the group for whom continuous ETCO2 monitoring was not used was 23.3% (95% confidence interval 13.4% to 36.0%). No unrecognized misplaced intubations were found in patients for whom paramedics used continuous ETCO2 monitoring. Failure to use continuous ETCO2 monitoring was associated with a 23% unrecognized misplaced intubation rate.

Incorrect assembly of non‐return valve of an Oxylog ventilator

We wish to report a critical incident during use of a Draeger Oxylog ventilator. Transfer was arranged for a burns victim whose lungs were mechanically ventilated. In preparation for the transfer he was changed to a Draeger Oxylog ventilator (Draeger Medical Ltd, Hertfordshire, UK) and the end-tidal carbon dioxide continually analysed. The initial end-tidal carbon dioxide measurement was 5.1 kPa, but within minutes this value increased to 11.0 kPa in association with a raised inspired concentration of carbon dioxide (1.5 kPa). Arterial blood gas analysis confirmed an elevated Paco2 of 13 kPa. The patient was reconnected to the ICU ventilator and ventilated to normocapnia. There appeared to be adequate chest expansion and appropriate movements of the pressure gauge on the ventilator were observed, but no gas flow could be detected from the PEEP valve situated on the expiratory port and the characteristic expiratory noise was absent. The Oxylog ventilator was examined closely and the non-return valve unit was discovered to have been incorrectly assembled such that the dark red ‘mushroom’ part of the valve had been inserted the wrong way around (see Figure 3). The result was that the patient was being ventilated predominantly with rebreathed gases. The correct assembly is shown in Figure 4. It is likely that the patient would have suffered an adverse event during the transfer had this error not been recognised at the bedside before departure. This was avoided by use of continuous end-tidal carbon dioxide monitoring to confirm the adequacy of ventilation on the new ventilator, as recommended by a number of professional organisations [1, 2]. The main learning point from this incident is that it is essential to confirm that the patient is stable on the transfer trolley and with the equipment that will be used for the transfer before leaving the relative safety of the parent unit. Incorrect assembly of non-return valve of Oxylog ventilator. Correct assembly of valve. We would like to thank Drs Thomas and Kuppurao for their report and for the opportunity to reply. From the information given in the letter we were not able to establish the exact model of Oxylog ventilator referred to. Therefore, we can only assume from studying the patient valve shown in the attachment sent to us that the Oxylog ventilator mentioned is either an Oxylog 1 or an Oxylog 1000. Our assumption is further supported by the fact that no mention or information is given in the article of any alarms being generated. This strongly suggests that an Oxylog 1 ventilator was being used and our following comments relate to this model. The Oxylog 1 ventilator is an early model in the ‘Dräger Oxylog family’ of emergency ventilators. It was first introduced into service in the 1980s and provided settings for minute volume, frequency, ‘air mix/no air mix’ and an on/off switch. Our initial concern with the letter is prompted by the fact that no reference is made to the manufacturer's Instructions for Use or the pre-use checks recommended in these [1]. Incorrect assembly of the check valve ‘dark red mushroom’ within the patient valve suggests that the valve was not assembled correctly as illustrated to users in the Instructions for Use. These instructions also have clear diagrams and explanations for cleaning, disinfecting, re-assembly and testing of the device. We would not disagree with the principle of the main learning point in the letter but consider it should be expanded further. To help ensure patient stability with the equipment and prior to leaving the safety of the parent unit, users should perform pre-use checks as detailed in the Instructions for Use before connecting the ventilator to the patient. M. S. RedpathDraeger Medical UK Ltd Hemel Hempstead HP2 7BW, UK E-mail: [email protected]