Comparison of the pulmonary dead-space fraction derived from ventilator volumetric capnography and a validated equation in the survival prediction of patients with acute respiratory distress syndrome

Purpose： This prospective observational study aims to evaluate the accuracy of dead-space fraction derived from the ventilator volumetric capnography （volumetric CO2） or a prediction equation to predict the survival of mechanically ventilated patients with acute respiratory distress syndrome （ARDS）. Methods： Consecutive VDJVT measurements were obtained based upon a prediction equation validated by Frankenfield et al for dead-space ventilation fraction： VD/VT = 0.320 ＋ 0.0106 （PaCO2-ETCO2） 4- 0.003 （RR） ＋ 0.0015 （age） in adult patients who had infection-related severe pneumonia and were confirmed as having ARDS. Here PaCO2 is the arterial partial pressure of carbon dioxide in mmHg; ETC02, the end- tidal carbon dioxide measurement in mmHg; RR, respiratory rate per minute; and age in years. Once the patient had intubation, positive end expiratory pressure was adjusted and after Phigh reached a steady state, VD/VT was measured and recorded as the data for the first day. VD/VT measurement was repeated on days 2, 3, 4, 5 and 6. Meanwhile we collected dead-space fraction directly from the ventilator volu- metric CO2 and recorded it as Vd/Vt. We analyzed the changes in VD/VT and Vd/Vt over the f-day period to determine their accuracy in predicting the survival of ARDS patients. Results： Overall, 46 patients with ARD5 met the inclusion criteria and 24 of them died, During the first 6 days of intubation, VD/VT was significantly higher in nonsurvivors on day 4 （0.70 ± 0,01 vs 0.57 ± 0.01 ）, day 5 （0.73 ± 0.01 vs, 0.54 ± 0.01 ）, and day 6 （0.73 ±0,02 vs. 0.54 ± 0.01 ） （all p - 0.000）. Vd/Vt showed no significant difference on days 1-4 but it was much higher in nonsurvivors on day 5 （0.45 ± 0.04 vs. 0.41 ±0.06） and day 6 （0.47 ± 0,05 vs. 0.40 ± 0.03） （both p - 0.008）. VD/VT on the fourth day was more accurate to predict survival than Vd/Vt. The area under the receiver-operating characteristic curve for VD/VT and Vd/Vt in evaluating ARDS patients survival was day 4 （0,974 ± 0.093 vs. 0.701 ± 0.023, p = 0.0024） with the 95% confidence interval being 0.857-0.999 vs, 0.525-0.84L Conclusion： Compared with Vd/Vt derived from ventilator volumetric CO2, VD/VT on day 4 calculated by Frankenfield et al＇s equation can more accurately predict the survival of ARDS patients.

Novel device for monitoring respiratory rate during endoscopy-A thermodynamic sensor

BACKGROUND Monitoring ventilation accurately is an indispensable aspect of patient care in procedural settings.The current gold standard method of monitoring ventilation is by measuring exhaled carbon dioxide concentration,known as capnography.A new device utilizing thermodynamic measurement,the Linshom Respiratory Monitoring Device(LRMD),has been designed to measure respiratory rate(RR)by using the temperature of exhaled breath.We hypothesized that the temperature sensor is at least equivalent in accuracy to capnography in monitoring ventilation.AIM To determine if the temperature sensor is equivalent to capnography in monitoring procedural ventilation.METHODS In this prospective study,participants were individually fitted with a face mask monitored by both LRMD and capnography.The following data were collected:gender,age,body mass index,type of procedure,and doses of medication.For each patient,we report the mean RR for each device as well as the mean difference.All analyses were performed using SAS,and a P<0.05 was considered statistically significant.RESULTS Twelve consecutive patients undergoing endoscopic procedures at our institution were enrolled.Four patients were excluded due to incomplete data,inadequate data,patient cooperation,and capnography failure.Overall,we found that LRMD RR highly correlated to capnography RR(P<0.001);the average capnography RR increases by 0.66 breaths for every one additional breath measured by the LRMD.In addition,apnea rates were 7.4%for the capnography and 6.4%for the LRMD(95%confidence interval:0.92-1.10).CONCLUSION The LRMD correlated with the gold standard capnography with respect to respiratory rate detection and apnea events.The LRMD could be used as an alternative to capnography for measuring respiration in endoscopy.

Comparison of Acoustic Respiration Rate, Impedance Pneumography and Capnometry Monitors for Respiration Rate Accuracy and Apnea Detection during GI Endoscopy Anesthesia

Study Objective: To assess the accuracy of respiration rate measurements and the ability to detect apnea by capnometry, impedance pneumography and a new method, acoustic respiration rate monitoring, in anesthetized patients undergoing gastrointestinal endoscopy procedures. Design: Prospective observational study. Setting: Endoscopy procedures laboratory. Patients: 98 patients scheduled for upper gastrointestinal endoscopy with propofol-based anesthesia. Interventions: Patients were monitored for respiration rate with acoustic respiration rate monitoring, capnometry and impedance pneumography and values were compared to the manual counting of breaths by observation of chest wall movements. Additionally, when any respiration rate monitor indicated a cessation of breathing for 30 seconds or greater, the presumed apnea was confirmed by direct observation of the patient for absence of chest wall movements. Measurements and Main Results: Bias and precision for respiration rate measurement was 0 ± 1.0 bpm for acoustic monitoring, 4.8 ± 15.1 bpm for capnometry and 0.4 ± 5.9 bpm for impedance pneumography. Sensitivity and specificity for detection of apnea was 73% and 93% for acoustic monitoring, 73% and 12% for capnometry and 45% and 93% for impedance pneumography. Conclusions: Acoustic respiration rate monitoring was found to be accurate for assessment of respiration rate and to have similar or better sensitivity and specificity for detection of apnea compared to capnometry and impedance pneumography in the setting of upper GI endoscopy.

Validation of Novel Completely Sealed Nasal Positive Airway Pressure Device: SuperNO₂VA™EtCO₂Measurement and Pressure Test Performance

Background: SuperNO2VA™ Et Nasal Mask (Vyaire Medical, Inc., United States) is a new nasal mask with an integrated sampling hood to capture exhaled gases and enable accurate measurements of end tidal carbon dioxide (EtCO2). The authors hypothesized that the SuperNO2VA Et design would measure EtCO2 more accurately than a predicate EtCO2 sampling line, the Smart CapnoLine® Plus, Adult/Intermediate CO2 Oral-Nasal Set (Medtronic, United States). Methods: A simulated patient setup enabled comparison of the accuracy of CO2 measurements within the SuperNO2VA Et and a predicate device for eight condition combinations of input CO2;breath rate and tidal volume (VT);and O2 flow rates. These tests were repeated with simulating Nasal Breathing and Oral Breathing. Results: Testing demonstrated that measurements of 1% and 5% input CO2 within the SuperNO2VA Et were accurate for a range of respiratory rates, VT, O2 flows, and CO2 concentrations. CO2 measurement errors were significantly larger for the Oral-Nasal Set compared to the SuperNO2VA Et for both 1% Input CO2 (-0.12%vol vs. -0.01%vol, p = 0.0005) and 5% Input CO2 (-0.93%vol vs. -0.08%vol, p < 0.0001). At 5% Input CO2, eight of the 12 trials for the Oral-Nasal Set failed to meet the ISO accuracy specification, while all SuperNO2VA Et measurements met the specification. The accuracy of CO2 measurement within the SuperNO2VA were not different for Oral and Nasal Breathing trials for both CO2 concentration (1%: p = 0.33, 5%: p = 0.064). With the Oral-Nasal Set, CO2 measurements were lower during Oral compared to Nasal Breathing (1%: p = 0.0005, 5%: p = 0.0091). Conclusions: Based on performance outcomes, use of the SuperNO2VA Et offers significantly more accurate measurement of EtCO2 than the predicate EtCO2 sampling line. Measurements of EtCO2 within the SuperNO2VA Et are accurate over a range of CO2, breathing rates, tidal volumes, and O2 flows, as well as for nasal and oral breathing.

End-tidal capnometry during emergency department procedural sedation and analgesia： a randomized, controlled study

BACKGROUND:This prospective,randomized trial was undertaken to evaluate the utility of adding end-tidal capnometry(ETC)to pulse oximetry(PO)in patients undergoing procedural sedation and analgesia(PSA)in the emergency department(ED).METHODS:The patients were randomized to monitoring with or without ETC in addition to the current standard of care.Primary endpoints included respiratory adverse events,with secondary endpoints of level of sedation,hypotension,other PSA-related adverse events and patient satisfaction.RESULTS:Of 986 patients,501 were randomized to usual care and 485 to additional ETC monitoring.In this series,48%of the patients were female,with a mean age of 46 years.Orthopedic manipulations(71%),cardioversion(12%)and abscess incision and drainage(12%)were the most common procedures,and propofol and fentanyl were the sedative/analgesic combination used for most patients.There was no difference in patients experiencing de-saturation(Sa O2<90%)between the two groups;however,patients in the ETC group were more likely to require airway repositioning(12.9%vs.9.3%,P=0.003).Hypotension(SBP<100 mm Hg or<85 mm Hg if baseline<100 mm Hg)was observed in 16(3.3%)patients in the ETC group and 7(1.4%)in the control group(P=0.048).CONCLUSIONS:The addition of ETC does not appear to change any clinically significant outcomes.We found an increased incidence of the use of airway repositioning maneuvers and hypotension in cases where ETC was used.We do not believe that ETC should be recommended as a standard of care for the monitoring of patients undergoing PSA.

A lightweight mainstream capnometer with very low dead space volume is useful monitor for neonates with spontanous and mechanical ventilation: Pilot study

Objects: The purpose of this study was to observe a correlation between PETCO2 and PaCO2 in intubated neonates under intermittent mandatory ventilation with spontaneous breathing. Material and methods: A total of 55 paired PETCO2 measured by mainstream capnometry and PaCO2 values were obtained from 4 intubated neonates in our neonatal intensive care units at Nagano Children’s Hospital, Nagano, Japan. Results: PETCO2 and PaCO2 were significantly correlated (r2 = 0.928, p ETCO2 and mean PETCO2 correlated strongly with PaCO2 (maximum PETCO2: r2 = 0.9401, p ETCO2: r2 = 0.8587, p 2 also correlated with minimum PETCO2 (r2 = 0.2884, p ETCO2 (p ETCO2 (p 2 and PETCO2. Conclusion: Present study showed that a good correlation exists between PETCO2 and PaCO2 in intubated neonates under intermittent mandatory ventilation with spontaneous breathing. Lightweight with low amounts of dead space mainstream capnometry can be used as noninvasive monitor in incubated neonates with spontaneous breathing.