A flow-through capnometer for obstructive sleep apnea

A Novel Nasal Cannula Type Mainstream Capnometer System Capable of Oxygen Administration

Capnometry is a method to measure carbon dioxide (CO₂) in exhaled gas and has been used to monitor patient's respiratory status. During moderate or deep sedation, monitoring for the presence of exhaled CO₂ is recommended for evaluating the adequacy of ventilation. Oxygen administration is usually given to patients with a nasal cannula to avoid hypoxia during sedation. However, the flow of oxygen administration can interfere with CO₂ measurement. We developed a nasal cannula type adapter called cap-ONE nasal adapter system based on the mainstream capnography which is designed to monitor CO₂ while supplying oxygen. In this study, we evaluated the basic performance of the system as compared with a conventional device using a spontaneous breathing model. The cap-ONE nasal adapter system could accurately measure PetCO₂ without being disturbed by oxygen flow and efficiently supply oxygen.

A Novel Mainstream Capnometer System for Non-invasive Positive Pressure Ventilation

Capnometry is a method to measure carbon dioxide (CO₂) in exhaled gas and it has been used to monitor patient respiratory status. CO₂ monitoring is also used for patients receiving non-invasive positive pressure ventilation (NPPV) therapy during mechanical ventilation. Ventilators actively dilute exhaled gas during non-invasive ventilation. In order to accurately measure end-tidal CO₂, an adequate amount of expired gas needs to be filled in a CO₂ measurement cell before expiratory positive airway pressure (EPAP) gas from the ventilator arrives to the cell. This is the reason why it is difficult to measure CO₂ stably during non-invasive ventilation using the conventional CO₂ measurement method. Therefore, we developed NPPV cap-ONE mask, which accurately measures CO₂ in exhaled gas during non-invasive ventilation. In this study, we evaluated the basic performance of the NPPV cap-ONE mask system. The NPPV cap-ONE mask system could accurately measure CO₂ in exhaled gas comparing to the conventional device in this study.

Novel mainstream capnometer system is safe and feasible even under CO2 insufflation during ERCP-related procedure: a pilot study

Background and aims

There is a need to safely achieve conscious sedation during endoscopic retrograde cholangiopancreatography (ERCP). We evaluated the safety and feasibility of a mainstream capnometer system to monitor apnoea during ERCP under CO₂ insufflation.

Methods

Non-intubated adult patients undergoing ERCP-related procedures with intravenous sedation were enrolled. End-tidal CO₂ (EtCO₂) was continuously monitored during the procedure under CO₂ insufflation using a mainstream capnometer system, comprising a capnometer and a specially designed bite block for upper gastrointestinal endoscopy and ERCP. Oxygen saturation (SpO₂) was also monitored continuously during the procedure. In this study, we evaluated the safety and feasibility of the capnometer system.

Results

Eleven patients were enrolled. Measurement of EtCO₂ concentration was possible from the beginning to the end of the procedure in all 11 cases. There was no measurement failure, dislocation of the bite block, or adverse event related to the bite block. Apnoea linked to hypoxaemia occurred five times (mean duration, 174.4 s).

Conclusion

This study confirmed that apnoea was detected earlier than when using a percutaneous oxygen monitor. Measurement of EtCO₂ concentration using the newly developed mainstream capnometer system was feasible and safe even under CO₂ insufflation.

A novel mainstream capnometer system for endoscopy delivering oxygen

Capnometry is a method to measure carbon dioxide (CO₂) in exhaled gas and it has been used in patients to monitor their respiratory status. Monitoring of exhaled CO₂ during endoscopic procedures has been shown to be effective in detecting drug-induced respiratory depression. Oxygen (O₂) supplementation is given to patients to abolish hypoxia during endoscopy. However, oxygen administration can interfere with CO2 measurement owing to oxygen flow. Therefore, we developed cap-ONE Biteblock for patients undergoing endoscopy with oxygen supply to measure CO₂ accurately. In this study we evaluated the basic performance of cap-ONE Biteblock. The cap-ONE Biteblock system could accurately measure CO₂ and efficiently supply O₂ comparing to conventional devices via a bench study.

Low partial pressure of end-tidal carbon dioxide predicts left ventricular assist device implantation in patients with advanced chronic heart failure

BACKGROUND

This study aimed to clarify the prognostic impact of partial pressure of end-tidal carbon dioxide (PETCO₂) in patients with advanced chronic heart failure (HF).

METHODS

Forty-eight patients (mean age 43.1±11.9years, 32 males) with chronic HF (44 with non-ischemic and 4 with ischemic cardiomyopathy) were prospectively enrolled. Echocardiography, blood tests, pulmonary function testing, and PETCO₂ measurements were performed as noninvasive tests, whereas right heart catheterization and arterial blood gas analysis were conducted as invasive tests. The primary end point of this study was left ventricular assist device (LVAD) implantation or cardiac death.

RESULTS

Eighteen patients underwent LVAD implantation at the Interagency Registry for Mechanically Circulatory Support (INTERMACS) profile 3 during the follow-up period, and no patient died. PETCO₂ was significantly lower in a stepwise manner with New York Heart Association functional class (class I or II, 34.2±9.3mmHg vs. class III or IV, 27.7±2.5mmHg; p<0.001). Univariate and multivariate Cox proportional hazard models and time-dependent receiver operating characteristic curve analysis revealed that PETCO₂≤31mmHg is an independent noninvasive predictor of LVAD implantation. Univariable and multivariable linear regression analyses showed that pulmonary arterial pressure was independently and highly correlated with PETCO₂ (r²=-0.512, p<0.001).

CONCLUSIONS

Among various noninvasive clinical parameters investigated, PETCO₂ was the independent predictor of LVAD implantation at the INTERMACS profile 3 in patients with chronic HF. Pulmonary congestion may significantly contribute to decreases in PETCO₂ in patients with HF.

A novel mainstream capnometer system for polysomnography integrated with measurement of nasal pressure and thermal airflow

Capnometry is a method to measure carbon dioxide (CO(2)) in exhaled gas and its use during polysomnography (PSG) for diagnostic of sleep apnea-hypopnea syndrome is expanding. However, some problems exist for using capnometer in combination with other respiratory monitoring devices because capnometry requires additional sampling cannula or airway adapter attached to patients. To resolve these problems, we developed a novel mainstream capnometer system for PSG, which is designed to integrate multiple devices for measuring respiratory parameters. This system may provide comfortable and stable PSG including capnometry. We evaluated the basic performance of this system using a spontaneous breathing model. The result indicates that this newly developed system works adequately in PSG and moreover has superior characteristics of capnography signal and measurement stability against displacement of sensors, compared to conventional devices.

Evaluation of transcutaneous and end-tidal carbon dioxide levels during inhalation sedation in volunteers

Measurement of end-tidal carbon dioxide (PETCO2) is useful because of its noninvasiveness, continuity, and response time when sudden changes in ventilation occur during inhalation sedation. We compared the accuracy of PETCO2 using a nasal mask and nasal cannula with the accuracy of transcutaneous carbon dioxide (TC-CO2) and determined which method is more useful during inhalation sedation in volunteers. We used a modified nasal mask (MNM) and modified nasal cannula (MNC) for measurement of PETCO2. The capnometer measured PETCO2 in the gas expired from the nasal cavity by means of two devices. The volunteers received supplemental O2 by means of each device at a flow rate of 6 L/min. After the volunteers lay quietly for 5 min with a supply of 100 % O2, they received supplemental N2O by means of each device at concentrations of 10, 20, and 25 % for 5 min and 30 % for 25 min. The correlation coefficient was poorer in the MNM than in the MNC, and the mean difference between TC-CO2 and PETCO2 in the MNM was greater than that in the MNC. The difference between the TC-CO2 and PETCO2 ranged from 3 to 6 mmHg in the MNM and from 2 to 5 mmHg in the MNC. The difference between two variables against the TC-CO2 and the CO2 waveforms obtained by means of the two devices were within the clinically acceptable range. Our two devices can provide continuous monitoring of PETCO2 with a supply of N2O/O2 in patients undergoing inhalation sedation.

Accuracy of end-tidal CO2 measurement through the nose and pharynx in nonintubated patients during digital subtraction cerebral angiography

OBJECTIVE

To determine the accuracy of end-tidal CO2 (PETCO2) obtained in the nose through the Smart CapnoLine and in the pharynx through the modified Filterline H Set with supplemental oxygen at 5 L/min in nonintubated patients undergoing digital subtraction cerebral angiography (DSA).

TYPE OF STUDY

Prospective, observational.

PATIENTS

Twenty patients with disturbance of consciousness because of brain disease, who will receive DSA.

METHODS

PETCO2 was measured in the nose through the Smart CapnoLine and in the pharynx using the modified Filterline H Set that was inserted through the nasopharyngeal airway. Oxygen was administered through the Smart CapnoLine at a rate of 5 L/min. Five minutes after a constant and normally shaped capnography waveform, arterial blood was drawn from an indwelling femoral catheter for analyzing arterial CO2 partial pressure (PaCO2), and PETCO2 that was measured through the nose and the pharynx were simultaneously recorded. After the DSA procedure, PaCO2 was analyzed again. Data were analyzed with Pearson correlation and Bland-Altman analysis.

RESULTS

PETCO2 sampled from both the nose and the pharynx was significantly correlated with PaCO2, and the correlation coefficients had approximate values, 0.832 (P<0.0001) for PaCO2 with PETCO2 through the nose and 0.836 (P<0.0001) for PaCO2 with PETCO2 through the pharynx. The mean bias±SD for PETCO2 and PaCO2 was 4.53±2.76 mm Hg (nose) and 3.22±2.86 mm Hg (pharynx). The 95% level of agreement for PETCO2 and PaCO2 ranged from -0.90 to 9.95 mm Hg (nose) and from -2.39 to 8.82 mm Hg (pharynx). End-tidal CO2 measurements through the nose and the pharynx had comparable performance. The correlation of PETCO2 measured through the nose and the pharynx was 0.971 (P<0.001). The difference between PETCO2 measured through the nose and the pharynx was 1.31±1.25 mm Hg, and t test results showed that arterial to end-tidal CO2 pressure difference (Pa-ETCO2) in sampling through the nose was significantly greater than Pa-ETCO2 sampling through the pharynx (P<0.05).

CONCLUSIONS

In a clinical setting, end-tidal CO2 measurements sampled from the nose and the pharynx were accurate and reliable in nonintubated patients with a nasopharynx airway in place during DSA.

A novel mainstream capnometer system for non-intubated pediatric patients requiring oxygen administration

Capnometer has been widely used as a respiratory monitor. Stable carbon dioxide (CO(2)) monitoring of non-intubated patient is especially problematic due to the frequent occurrence of tube obstruction and it could be even more difficult when oxygen is being administered. Oxygen is often administered by an oxygen mask or oxygen nasal cannula; however there are some problems with these methods. For oxygen masks, it is necessary to provide high-flow oxygen to prevent rebreathing of exhaled CO(2), and as for oxygen nasal cannula, it is incapable of increasing the oxygen concentration and patient may feel uncomfortable during oxygen administration because it could dry nasal mucous. To solve these problems, we developed a novel mainstream capnometer system, which provides stable monitoring of exhaled CO(2) while administering oxygen. This capnometer system has a mask with an opening large enough to facilitate the observation of patient's nose and mouth and the procedures such as daily oral care. Furthermore, the outer rim of the mask is designed to effectively retain oxygen flow without causing rebreathing.