OBJECTIVE: Air leak (AL) is the most frequent adverse event after thoracic surgery. When AL occurs, the concentration of the principal gas in the pleural space should be similar to that of air exhaled. Accordingly, we tried to develop a new method to identify AL by analyzing pCO2 levels in the air flow from the chest drainage using capnography.
METHODS: This is a prospective observational study of 104 patients who underwent VATS surgery between January 2020 and July 2021. Digital drainage systems were used to detect AL.
RESULTS: Eighty-two patients (79%) had lung resection. Among them, 19 had post-operative day 1 air leaks (median 67 ml/min). AL patients had higher intrapleural CO2 levels (median 24 mmHg) (p < 0.001). Median chest drainage duration was 2 days (range 1.0-3.0). Univariable logistic regression showed a linear and significant association between intrapleural CO2 levels and AL risk (OR 1.26, 95% CI 1.17-1.36, p < 0.001, C index: 0.94). The Univariable Gamma model demonstrated that an elevation in CO2 levels was linked to AL on POD1 (with an adjusted mean effect of 7.006, 95% CI 1.59-12.41, p = 0.011) and extended duration of drainage placement (p < 0.001).
CONCLUSIONS: Intrapleural CO2 could be an effective tool to assess AL. The linear association between variables allows us to hypothesize the role of CO2 in the identification of AL. Further studies should be performed to identify a CO2 cutoff that will standardize the management of chest drainage.

By continually monitoring end-tidal carbon dioxide concentrations, capnography can detect abnormal ventilation or apnoea early. This randomized, controlled study explored the effect of early intervention with capnography on the incidence of hypoxia in mildly obese patients undergoing sedation for esophagogastroduodenoscopy (EGD) and colonoscopy.
This is a single-center, randomized, single-blind, parallel-assignment, controlled trial. Mildly obese patients (28 kg/m2 ≤ BMI < 40 kg/m2) undergoing sedation for EGD and colonoscopy were randomly assigned to either the standard or capnography group. Standard cardiopulmonary monitoring equipment was used in both groups, and additional capnography was performed in the capnography group. In the event of inadequate alveolar ventilation during sedation, five interventions were administered in sequence (a-e) : a: increasing oxygen flow (5 L/min); b: a chin lift or jaw thrust maneuver; c: placement of the nasopharyngeal airway and chin lift; d: mask positive-pressure ventilation, and e: ventilator-assisted ventilation with tube insertion. The primary outcome was the incidence of hypoxia (SpO2 < 90%, ≥ 10 s) in each group. The secondary outcomes included the incidence of severe hypoxia (SpO2 ≤ 85%), subclinical respiratory depression (90% ≤ SpO2 < 95%), interventions, minimum SpO2 during operation, patient satisfaction, endoscopist satisfaction, and other adverse events of anesthesia sedation.
228 patients were included (capnography group = 112; standard group = 113; three patients were excluded) in this study. The incidence of hypoxia was significantly lower in the capnography group than in the standard group (13.4% vs. 30.1%, P = 0.002). Subclinical respiratory depression in the capnography group was higher than that of the standard group (30.4% vs. 17.7%, P = 0.026). There was only a 5.4% incidence of severe hypoxia in the capnography group compared with 14.2% in the standard group (P = 0.026). During sedation, 96 and 34 individuals in the capnography and standard groups, respectively, underwent the intervention. There was a statistically significant difference (P < 0.0001) in the number of the last intraoperative intervention between the two groups ( a:47 vs. 1, b:46 vs. 26, c:2 vs. 5, d:1 vs. 2, e:0 vs. 0 ). No significant differences were found between the two groups in terms of minimum SpO2 during operation, patient satisfaction, or endoscopist satisfaction rating. There was no statistically significant difference in adverse events of anesthesia sedation between the two groups.
Capnography during sedation for EGD and colonoscopy allows for the detection of apnea and altered breathing patterns in mildly obese patients before SpO2 is reduced. Effective intervention measures are given to patients within this time frame, which reduces the incidence of hypoxia and severe hypoxia in patients.
Ethical approval was granted by the Medical Ethics Committee (Chairperson Professor Tian Hui) of Qilu Hospital, Shandong University ((Ke) Lun Audit 2021 (186)) on 15/07/2021. The study was registered ( https://www.chictr.org.cn ) on 23/10/2021(ChiCTR2100052234). Designed and reported using CONSORT statements.

BACKGROUND: Hypoxia is a very common adverse event that occurs during gastrointestinal endoscopy under sedation, especially in older patients, owing to limited reservation of heart, brain, lung, and other organs. Prolonged or severe hypoxia can cause ischemia of the coronary artery and permanent nervous system damage, and even result in death. Hence, it is imperative to reduce or prevent hypoxia during gastrointestinal endoscopy under sedation in older patients. Although several oxygen delivery methods would reduce hypoxia during this procedure, early detection of respiratory depression and early administration of intervention would be the best method to reduce or even confirm the hypoxia. Capnographic monitoring is reportedly more sensitive for detecting respiratory depression before the onset of hypoxia than the current clinical routine monitoring of pulse oxygen saturation; however, its effect is controversial. Therefore, in this study, we aimed to improve the safety of gastrointestinal endoscopy under sedation in older patients.
METHODS: A multicenter, randomized, single-blind, two-arm parallel-group, controlled with an active comparator, interventional superiority clinical trial will be conducted to evaluate the impact of an additional capnographic monitoring-based intervention on the incidence of hypoxia in older patients. Patients (n = 1800) scheduled for gastrointestinal endoscopy with propofol sedation will be randomly assigned to either a control or interventional arm, wherein standard or capnographic monitoring is implemented, respectively.
CONCLUSIONS: This study primarily aims to examine whether an additional capnographic monitoring-based intervention can reduce the incidence of hypoxia in older patients during gastrointestinal endoscopy under propofol and sufentanil sedation. The results of this study may extensively impact gastrointestinal endoscopy under sedation and the development of associated guidelines.
BACKGROUND: ClinicalTrials.gov NCT05030870. Registered on September 1, 2021.

BACKGROUND: Misplacement of the nasogastric tube in the respiratory tract could cause serious complications and even death. Thus, nasogastric tube verification is necessary for optimal patient safety and comfort. Although end-tidal carbon dioxide detection is considered an effective approach to determine nasogastric tube location, there is a paucity of up-to-date evidence.
OBJECTIVE: To review the diagnostic accuracy of end-tidal carbon dioxide detection in determining inadvertent airway intubation and verifying correct placement of nasogastric tubes.
METHODS: A systematic review and meta-analysis.
METHODS: We searched clinical trials that evaluated the diagnostic accuracy of colorimetric capnometry or capnography in detecting nasogastric tubes located in the airway and differentiating between inadvertent airway intubation and correct nasogastric tube placement in any adult care setting. Four English language databases - Cochrane Central Register of Controlled Trials, MEDLINE, EMBASE, and CINAHL - and four Chinese language databases - China Biomedical Literature Database, WanFang Data, China National Knowledge Infrastructure, and Airiti Library - were searched from July 2009 to March 2021. Clinical trial registration databases and reference lists of included studies and relevant reviews were also searched. Two reviewers extracted the data of all included studies using a data extraction form. Two reviewers assessed the methodological quality independently with the Quality Assessment of Diagnostic Accuracy Studies-2 tool. We conducted meta-analysis using the hierarchical bivariate model and estimated the pool sensitivity and specificity of capnography and colorimetric capnometry. Forest plots were generated to display the results. Heterogeneity was investigated by meta-regression. The certainty of evidence was evaluated with the Grading of Recommendations Assessment, Development and Evaluations framework.
RESULTS: Of 1,155 records identified, seven new studies were added to this update and a total of 16 studies were analysed in the systematic review. The total absolute number of true positive, false negative, true negative, and false positive observations were 142, 6, 1,500, and 65 respectively. Low to very low certainty of evidence indicated that the use of colorimetric capnometry or capnography is potentially an effective method in differentiating between respiratory and nasogastric tube placement for critically ill adult patients. Pooled results (13 studies, 1,541 intubations) for sensitivity and specificity were 0.96 (95% confidence interval [0.88, 0.99]) and 0.99 (95% confidence interval [0.96, 1.00]), respectively.
CONCLUSIONS: Colorimetric capnometry and capnography may have the potential to be of high sensitivity and specificity for the detection of inadvertent airway nasogastric tube placements in critically ill adults. More evidence is required to generalize the updated findings to different types of patients and settings.

暂无摘要。

We aimed to evaluate a volumetric capnography (Vcap)-derived parameter, the volume of CO2 eliminated per minute and per kg body weight (VCO2/kg), as an indicator of the quality of chest compression (CC) and to predict the return to spontaneous circulation (ROSC) under stable ventilation status. Twelve male domestic pigs were utilized for the randomized crossover study. After 4 min of untreated ventricular fibrillation (VF), mechanical cardiopulmonary resuscitation and ventilation were administered. Following 5-min washout periods, each animal underwent two sessions of experiments: three types of CC quality for 5 min stages in the first session, followed by advanced life support, consecutively in two sessions. Different CC quality had a significant effect on the partial pressure of end-tidal carbon dioxide (PetCO2), VCO2/kg, aortic pressure (mean), aortic systolic pressure, aortic diastolic pressure, right atrial pressure (mean), and carotid blood flow (P < 0.05). With the improvement in CC quality, the values of PetCO2 and VCO2/kg also increased, and the difference between the groups was statistically significant (P < 0.05). The Spearman rank test revealed a significant correlation between the Vcap-derived parameters and hemodynamics. PetCO2 and VCO2/kg have similar capabilities for discriminating survivors from non-survivors, and the area under the curve for both was 0.97. VCO2/kg had similar performance as PetCO2 in reflecting the quality of CC and prediction of achieving ROSC under stable ventilation status in a porcine model of VF-related cardiac arrest. However, VCO2/kg requires a longer time to achieve a stable state after adjusting for quality of CC than PetCO2.

BACKGROUND: In this work we describe a breath emulator system, used to simulate temporal characteristics of exhaled carbon dioxide (CO2) concentration waveform versus time simulating how much CO2 is present at each phase of the human lung respiratory process. The system provides a method for testing capnometers incorporating fast response non-dispersive infrared (NDIR) CO2 gas sensing devices - in a clinical setting, capnography devices assess ventilation which is the CO2 movement in and out of the lungs. A mathematical model describing the waveform of the expired CO2 characteristic and influence of CO2 gas sensor noise factors and speed of response is presented and compared with measured and emulated data.
OBJECTIVE: A range of emulated capnogram temporal waveforms indicative of normal and restricted respiratory function demonstrated. The system can provide controlled introduction of water vapour and/ or other gases, simulating the influence of water vapour in exhaled breath and presence of other gases in a clinical setting such as anaesthetic agents (eg N2O). This enables influence of water vapour and/ or other gases to be assessed and modelled in the performance of CO2 gas sensors incorporated into capnography systems. As such the breath emulator provides a means of controlled testing of capnometer CO2 gas sensors in a non-clinical setting, allowing device optimisation before use in a medical environment.
METHODS: The breath emulator uses a unique combination of mass flow controllers, needle valves and a fast acting switchable pneumatic solenoid valve (FASV), used to controllably emulate exhaled CO2 temporal waveforms for normal and restricted respiratory function. Output data from the described emulator is compared with a mathematical model using a range of input parameters such as time constants associated with inhalation/ exhalation for different parts of the respiratory cycle and CO2 concentration levels. Sensor noise performance is modelled, taking into account input parameters such as sampling period, sensor temperature, sensing light throughput and pathlength.
RESULTS: The system described here produces realistic human capnographic waveforms and has the capability to emulate various waveforms associated with chronic respiratory diseases and early stage detection of exacerbations. The system has the capability of diagnosing medical conditions through analysis of CO2 waveforms. Demonstrated in this work the emulator has been used to test NDIR gas sensor technology deployed in capnometer devices prior to formal clinical trialling.

To evaluate the quantitative changes and diagnostic performance of volumetric capnography (VCap) parameters in patients with cough variant asthma.
This cross-sectional study enrolled 31 patients with cough variant asthma and 30 patients with chronic cough without asthma between November 2010 and March 2012. VCap measurements were recorded at baseline, during the five steps of the histamine challenge, and after bronchodilation with salbutamol. They were then compared between the baseline and histamine challenge, and between the two groups. Receiver operating characteristic curve analysis was performed for different VCap measurements.
The slope of phase III (dc\\dv3) and the ratio of phase III slope to phase II slope (SR23%) decreased from baseline upon challenge with 1.1 mg histamine in cough variant asthma patients but increased in patients with chronic cough without asthma. Additionally, the change upon challenge with 1.1 mg histamine in dc\\dv3 from baseline (S6-S1dc\\dv3) in cough variant asthma patients had the largest area under the curve (AUC) (0.814, 95% CI: 0.697-0.931; p<0.001). The AUC for change upon challenge with 1.1 mg histamine in SR23% from baseline was 0.755 (95%CI: 0.632-0.878; p<0.001). At a cutoff of 19.8, S6-S1 dc\\dv3 had a sensitivity of 74.2% and specificity of 90.0% and at a cutoff of 40.7, S6-S1 SR23% had a sensitivity of 48.4% and specificity of 96.7%.
Patients with cough variant asthma exhibit distinct VCap responses for dead space parameters upon challenge with histamine in comparison to patients with chronic cough. VCap parameters like phase III slope and phase III/phase II slope ratio could be used to aid the diagnosis of cough variant asthma.

We aimed to investigate whether the ability of the volumetric capnography-derived parameter, the volume of CO2 eliminated per minute and per kg body weight (V\'CO2 kg-1), in monitoring the quality of CPR and predicting the return of spontaneous circulation (ROSC) remains undisturbed by hyperventilation.
This randomised crossover study included 12 male domestic pigs. After 4 min of untreated ventricular fibrillation, mechanical CPR was administered. Following 5-min washout periods, each animal underwent two sessions of experiments; four 5-min ventilation trials followed by advanced life support, consecutively in the two sessions.
Different ventilation types had no significant impact on V\'CO2 kg-1 or haemodynamics. However, PETCO2 was significantly affected by the ventilation type and coronary perfusion pressure (P < 0.05). The means ± standard deviations of PETCO2 decreased linearly with an increase in the respiratory rate (RR) (P < 0.05). The PETCO2 decreased from 20.42 ± 9.51 to 16.16 ± 5.07 (P < 0.05) as the tidal volume increased from 10 to 20 mL min-1. No significant differences in V\'CO2 kg-1 were observed between the three RR levels of ventilation types (P = 0.274). Post hoc analysis demonstrated a significant difference between the highest value of V\'CO2 kg-1 in double tidal volume hyperventilation and normal ventilation and triple respiratory rate hyperventilation (P < 0.05). The AUC for V\'CO2 kg-1 and PETCO2 in discriminating between survivors and non-survivors was 0.80 and 0.71, respectively.
V\'CO2 kg-1 performs better than PETCO2 in monitoring the quality of CPR during hyperventilation. In predicting ROSC during variations in a ventilation state, V\'CO2 kg-1 has good predictive ability.

暂无摘要。