Comparing the Effect of Respiratory Physiotherapy and Positive End-Expiratory Pressure Changes on Capnography Results in Intensive Care Unit Patients with Ventilator-Associated Pneumonia

Background

While critically ill patients experience a life-threatening illness, they commonly develop ventilator-associated pneumonia (VAP) which can increase morbidity, mortality, and healthcare costs. The present study aimed to compare the effect of respiratory physiotherapy and increased positive endexpiratory pressure (PEEP) on capnography results.

Materials and Methods

This randomized control clinical trial was performed on 80 adult patients with VAP in the intensive care unit (ICU). The patients were randomized to receive either PEEP at 5 cm H2O, followed by a moderate increase in PEEP to 10 cm H2O, or PEEP at 5 cm H2O with respiratory physiotherapy for 15 min. The numerical values were recorded on the capnograph at minutes 1, 5, 10, 15, and 30 in both methods. Data collection instruments included a checklist and MASIMO capnograph.

Results

As evidenced by the obtained results, the two methods significantly differed in the excreted pCO2 (partial pressure of carbon dioxide) (P<0.0001). However, the average amount of excreted pCO2 was higher in the respiratory physiotherapy and PEEP intervention (38.151mmHg) in comparison with increasing PEEP alone method (36.184mmHg). Also, PEEP elevation method prolonged the time of the first phase (inhalation time) and the second phase while shortening the third phase (exhalation time) in capnography waves.

Conclusion

CO2 excretion in patients with VAP increased after respiratory physiotherapy. Further, physiotherapy demonstrated more acceptable results in CO2 excretion compared with PEEP changes in mechanically ventilated patients.

Videolaryngoscopy: Channelizing through Intensive Care Unit Intubations

How to cite this article: Kothekar AT, Wajekar AS, Joshi AV. Videolaryngoscopy: Channelizing through Intensive Care Unit Intubations. Indian J Crit Care Med 2023;27(2):85-86.

Ventilation rates measured by capnography during out-of-hospital cardiac arrest resuscitations and their association with return of spontaneous circulation

BACKGROUND

Clinical guidelines for adult out-of-hospital cardiac arrest (OHCA) recommend a ventilation rate of 8-10 per minute yet acknowledge that few data exist to guide recommendations. The goal of this study was to evaluate the utility of continuous capnography to measure ventilation rates and the association with return of spontaneous circulation (ROSC).

METHODS

This was a retrospective observational cohort study. We included all OHCA during a two-year period and excluded traumatic and pediatric patients. Ventilations were recorded using non-invasive continuous capnography. Blinded medically trained team members manually annotated all ventilations. Four techniques were used to analyze ventilation rate. The primary outcome was sustained prehospital ROSC. Secondary outcomes were vital status at the end of prehospital care and survival to hospital admission. Univariable and multivariable logistic regression models were constructed.

RESULTS

A total of 790 OHCA were analyzed. Only 386 (49%) had useable capnography data. After applying inclusion and exclusion criteria, the final study cohort was 314 patients. The median ventilation rate per minute was 7 (IQR 5.4-8.5). Only 70 (22%) received a guideline-compliant ventilation rate of 8-10 per minute. Sixty-two (20%) achieved the primary outcome. No statistically significant associations were observed between any of the ventilation parameters and patient outcomes in both univariable and multivariable logistic regression models.

CONCLUSIONS

We failed to detect an association between intra-arrest ventilation rates measured by continuous capnography and proximal patient outcomes after OHCA. Capnography has poor reliability as a measure of ventilation rate. Achieving guideline-compliant ventilation rates remains challenging.

Comparison of ultrasonography, clinical method and capnography for detecting correct endotracheal tube placement- A prospective, observational study

Background and Aims

In emergency airway management, unstable haemodynamics of the patients calls for the early need to detect correct endotracheal tube (ETT) placement. Ultrasonography has an advantage of being readily available along with being non-invasive and providing real time images. We aimed to study the usefulness of tracheal ultrasonography and use it as a tool to assess correct tracheal intubation in patients in the intensive care unit.

Methods

This was a hospital-based observational study. The study included 92 patients who needed and were taken up for endotracheal intubation. Tube placement was confirmed simultaneously by three different observers with their respective method, i.e., ultrasonography, clinical method and capnography.

Results

Sensitivity, specificity, positive predictive value (PPV) and negative predictive value (NPV) of ultrasonography against capnography were 100% each with P value of 1. However, for clinical method against capnography, the sensitivity was 96.5%, specificity 28.6%, PPV 94.3% and NPV 40% with P value of 0.727. Mean time taken to detect correct placement of the ETT by ultrasonography, capnography and clinical method was 4.93 s, 15.39s and 17.80s, respectively. Out of 92 intubations, 85 were tracheal and 7 were oesophageal. All intubations were detected accurately with ultrasonography and capnography, ultrasonography being faster. Clinical method correctly detected 82 out of 85 tracheal intubations and 2 out of 7 oesophageal intubations, and was therefore less accurate than the other two methods.

Conclusion

The study shows that ultrasonography is as reliable a method for confirmation of endotracheal intubation as capnography and is more reliable than clinical method. Besides, ultrasonography is faster than the other two methods.

Expiratory high-frequency percussive ventilation: a novel concept for improving gas exchange

Background

Although high-frequency percussive ventilation (HFPV) improves gas exchange, concerns remain about tissue overdistension caused by the oscillations and consequent lung damage. We compared a modified percussive ventilation modality created by superimposing high-frequency oscillations to the conventional ventilation waveform during expiration only (eHFPV) with conventional mechanical ventilation (CMV) and standard HFPV.

Methods

Hypoxia and hypercapnia were induced by decreasing the frequency of CMV in New Zealand White rabbits (n = 10). Following steady-state CMV periods, percussive modalities with oscillations randomly introduced to the entire breathing cycle (HFPV) or to the expiratory phase alone (eHFPV) with varying amplitudes (2 or 4 cmH₂O) and frequencies were used (5 or 10 Hz). The arterial partial pressures of oxygen (PaO₂) and carbon dioxide (PaCO₂) were determined. Volumetric capnography was used to evaluate the ventilation dead space fraction, phase 2 slope, and minute elimination of CO₂. Respiratory mechanics were characterized by forced oscillations.

Results

The use of eHFPV with 5 Hz superimposed oscillation frequency and an amplitude of 4 cmH₂O enhanced gas exchange similar to those observed after HFPV. These improvements in PaO₂ (47.3 ± 5.5 vs. 58.6 ± 7.2 mmHg) and PaCO₂ (54.7 ± 2.3 vs. 50.1 ± 2.9 mmHg) were associated with lower ventilation dead space and capnogram phase 2 slope, as well as enhanced minute CO₂ elimination without altering respiratory mechanics.

Conclusions

These findings demonstrated improved gas exchange using eHFPV as a novel mechanical ventilation modality that combines the benefits of conventional and small-amplitude high-frequency oscillatory ventilation, owing to improved longitudinal gas transport rather than increased lung surface area available for gas exchange.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12931-022-02215-2.

Efficacy of capnographic and bispectral index monitoring on trans-oral therapeutic endoscopy: A prospective observational study

BACKGROUND AND AIM

Oral therapeutic and invasive endoscopy requires deep sedation to reduce patient distress due to prolonged examination and procedures. The usefulness of capnography and bispectral index (BIS) monitoring in the early hypoxia detection in oral therapeutic and invasive endoscopy has yet to be evaluated. This study aimed to investigate the clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures.

METHODS

This is a prospective observational study. Trans-oral non-intubated therapeutic and/or invasive endoscopic procedures were performed with conventional monitoring (pulse oximetry, pulse, and blood pressure) as well as additional monitoring (BIS and end-tidal CO₂ concentration). Hypoxia is defined as oxygen saturation of <90% that lasts >15 s. The clinical impact of capnography and BIS monitoring on hypoxic events during oral therapeutic and invasive endoscopic procedures were investigated with the risk factors for hypoxia in each patient.

RESULTS

Patients with hypoxia had significantly more apneas detected using capnography than other patients. The multivariate analysis revealed the detected apnea by capnography as an independent risk factor for hypoxia (odds ratio: 3.48[95% confidence interval: 1.24-9.78], P = 0.02). The BIS was not significantly different as a risk factor for hypoxia; however, per-event analysis revealed significantly decreased BIS values over time in 3 min before hypoxic events.

CONCLUSIONS

Apnea detected by capnography was an independent predictor of hypoxia. The BIS value was not associated with hypoxia events; however, it showed a significant downward trend before hypoxia events.

Capnography in newborns under mechanical ventilation and its relationship with the measurement of CO2 in blood samples

INTRODUCTION

Monitoring the partial pressure of CO₂ (PCO₂) in newborns who require ventilation would allow avoiding hypocapnia and hypercapnia. The measurement of end-tidal carbon dioxide (ETCO₂) is an alternative rarely implemented in this population.

OBJECTIVE

To evaluate the relationship between ETCO₂ and PCO₂ in newborns.

METHODS

Cross-sectional study comparing two PCO₂ measurement methods, the conventional one by analysis of blood samples and the one estimated by ETCO₂. The study included hospitalized newborns that required conventional mechanical ventilation. The ETCO₂ was measured with a Tecme GraphNet® neo, a neonatal ventilator with an integrated capnograph, and we obtained the ETCO₂-PCO₂ gradient. We conducted correlation and Bland-Altman plot analyses to estimate the agreement.

RESULTS

A total of 277 samples (ETCO₂ / PCO₂) from 83 newborns were analyzed. The mean values ​​of ETCO₂ and PCO₂ were 41.36mmHg and 42.04mmHg. There was a positive and significant correlation between ETCO₂ and PCO₂ in the overall analysis (r=0.5402; P<.001) and in the analysis of each unit (P<.001). The mean difference was 0.68 mmHg (95% CI, -0.68 to 1.95) and was not significant. We observed a positive systematic error (PCO₂ > ETCO₂) in 2 of the units, and a negative difference in the third (PCO₂ < ETCO₂).

DISCUSSION

The correlation between ETCO and PCO₂ was significant, although the obtained values ​​were not equivalent, with differences ranging from 0.1mmHg and 20mmHg. Likewise, we found systematic errors that differed in sign (positive or negative) between institutions.

Capnography for Monitoring of the Critically Ill Patient

Capnography has been widely adopted in multiple clinical areas. The capnogram and end-tidal carbon dioxide offer a wealth of information, in the right clinical setting, and when properly interpreted. In this article, the authors aim to review the most common clinical scenarios during which capnography has been shown to be of benefit. This includes the areas of fluid responsiveness, cardiopulmonary resuscitation, and conscious sedation. They review the published literature, highlighting its pitfalls and identifying its limitations.

Proposals from a French expert panel for respiratory care in ALS patients

BACKGROUND

Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease characterized by progressive diaphragm weakness and deteriorating lung function. Bulbar involvement and cough weakness contribute to respiratory morbidity and mortality. ALS-related respiratory failure significantly affects quality of life and is the leading cause of death. Non-invasive ventilation (NIV), which is the main recognized treatment for alleviating the symptoms of respiratory failure, prolongs survival and improves quality of life. However, the optimal timing for the initiation of NIV is still a matter of debate. NIV is a complex intervention. Multiple factors influence the efficacy of NIV and patient adherence. The aim of this work was to develop practical evidence-based advices to standardize the respiratory care of ALS patients in French tertiary care centres.

METHODS

For each proposal, a French expert panel systematically searched an indexed bibliography and prepared a written literature review that was then shared and discussed. A combined draft was prepared by the chairman for further discussion. All of the proposals were unanimously approved by the expert panel.

RESULTS

The French expert panel updated the criteria for initiating NIV in ALS patients. The most recent criteria were established in 2005. Practical advice for NIV initiation were included and the value of each tool available for NIV monitoring was reviewed. A strategy to optimize NIV parameters was suggested. Revisions were also suggested for the use of mechanically assisted cough devices in ALS patients.

CONCLUSION

Our French expert panel proposes an evidence-based review to update the respiratory care recommendations for ALS patients in daily practice.

PaCO2-EtCO2 Gradient and D-dimer in the Diagnosis of Suspected Pulmonary Embolism

BACKGROUND

The diagnosis of pulmonary embolism (PE) because of nonspecific clinical presentation remains as a challenge for emergency physicians. Arterial to end-tidal partial pressure of carbon dioxide (P(a-Et) CO2) gradient may be useful in the evaluation of PE. This aimed to define the diagnostic role of P(a-Et)CO2 gradient by sidestream capnography, as a noninvasive method, and D-dimer in patients with PE.

MATERIALS AND METHODS

Two hundred and three patients with chest pain or dyspnea who attend the hospital emergency ward were enrolled over a study period at a single academic center. PE was confirmed by multidetector computed tomography (MDCT) scans. PaCO2, EtCO2, and D-dimer were measured within 24 h of MDCT by capnograph.

RESULTS

The combination of P(a-Et)CO2 gradient (cutoff >9.2 ng/ml) and D-dimer (cutoff >3011 ng/ml) with sensitivity and specificity of 30.2% and 87.2% showed a significant diagnostic value in detecting PE (area under the curve = 0.577, P = 0.045) but not alone (P > 0.05).

CONCLUSION

As the results show, the combination of P(a-Et)CO2 gradient and D-dimer can show an acceptable diagnostic value in detecting PE, although it suggests further research on evaluating the diagnostic value of P(a-Et)CO2 gradient and combining it with other diagnostic criteria to achieve a definite and generalizable result.

[I-Gel® laryngeal mask versus bag-valve-mask in instrumental cardiopulmonary resuscitation under capnographic monitoring: Cluster-randomized pilot clinical trial]

OBJECTIVE

To compare the basic airway and the advanced airway with the supraglottic device I-Gel®, by means of capnography during intermediate CPR.

DESIGN

Randomized experimental pilot study by groups.

SETTING

Out-hospital care basic life support units on the Island of Mallorca.

PARTICIPANTS

Adults attended after cardiorespiratory arrest of non-traumatic origin.

INTERVENTIONS

Advanced airway management during instrumental CPR with I-Gel® or basic CPR with bag-valve-mask, under capnographic monitoring.

MAIN MEASUREMENTS

Capnometric levels obtained according to the device used, number of insertions of the I-Gel®, cases without achieving correct insertion/ventilation by branches, achievement of ROSC in CPR and number of hospital live admissions.

RESULTS

Twenty-three cases were recruited for analysis. The insertion success rate of the I-Gel® was 92.9% at the first attempt, the mean capnometric values were 16.3mmHg in the control group and 27.4% in the intervention group. 34.8% (n=8) of the patients achieved spontaneous circulation recovery at some point and 26.1% (n=6) were admitted to hospital alive. The survival analysis, taking into account the arrival of the unit and the first minute of ventilations recorded together with the variable hospital admission, suggests a certain trend of greater survival in the intervention branch (P=.066).

CONCLUSIONS

The use of I-Gel® raises an improvement in the ventilation of the patients in PCR, evidenced by the mean capnometric values in the intervention group, finding no correlation with CPR outcome variables.

Mechanical active compression-decompression versus standard mechanical cardiopulmonary resuscitation: A randomised haemodynamic out-of-hospital cardiac arrest study

BACKGROUND

Active compression-decompression cardiopulmonary resuscitation (ACD-CPR) utilises a suction cup to lift the chest-wall actively during the decompression phase (AD). We hypothesised that mechanical ACD-CPR (Intervention), with AD up to 30 mm above the sternal resting position, would generate better haemodynamic results than standard mechanical CPR (Control).

METHODS

This out-of-hospital adult non-traumatic cardiac arrest trial was prospective, block-randomised and non-blinded. We included intubated patients with capnography recorded during mechanical CPR. Exclusion criteria were pregnancy, prisoners, and prior chest surgery. The primary endpoint was maximum tidal carbon dioxide partial pressure (p_MTCO₂) and secondary endpoints were oxygen saturation of cerebral tissue (SctO₂), invasive arterial blood pressures and CPR-related injuries. Intervention device lifting force performance was categorised as Complete AD (≥30 Newtons) or Incomplete AD (≤10 Newtons). Haemodynamic data, analysed as one measurement for each parameter per ventilation (Observation Unit, OU) with non-linear regression statistics are reported as mean (standard deviation). A two-sided p-value < 0.05 was considered as statistically significant.

RESULTS

Of 221 enrolled patients, 210 were deemed eligible (Control 109, Intervention 101). The Control vs. Intervention results showed no significant differences for p_MTCO₂: 29(17) vs 29(18) mmHg (p = 0.86), blood pressures during compressions: 111(45) vs. 101(68) mmHg (p = 0.93) and decompressions: 21(20) vs. 18(18) mmHg (p = 0.93) or for SctO₂%: 55(36) vs. 57(9) (p = 0.42). The 48 patients who received Complete AD in > 50% of their OUs had higher SctO₂ than Control patients: 58(11) vs. 55(36)% (p < 0.001).

CONCLUSIONS

Mechanical ACD-CPR provided similar haemodynamic results to standard mechanical CPR. The Intervention device did not consistently provide Complete AD.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov identifier (NCT number): NCT02479152. The Haemodynamic Effects of Mechanical Standard and Active Chest Compression-decompression During Out-of-hospital CPR.

Evaluation of the Integrated Pulmonary Index® during non-anesthesiologist sedation for percutaneous endoscopic gastrostomy

Standard monitoring of heart rate, blood pressure and arterial oxygen saturation during endoscopy is recommended by current guidelines on procedural sedation. A number of studies indicated a reduction of hypoxic (art. oxygenation < 90% for > 15 s) and severe hypoxic events (art. oxygenation < 85%) by additional use of capnography. Therefore, U.S. and the European guidelines comment that additional capnography monitoring can be considered in long or deep sedation. Integrated Pulmonary Index® (IPI) is an algorithm-based monitoring parameter that combines oxygenation measured by pulse oximetry (art. oxygenation, heart rate) and ventilation measured by capnography (respiratory rate, apnea > 10 s, partial pressure of end-tidal carbon dioxide [PetCO2]). The aim of this paper was to analyze the value of IPI as parameter to monitor the respiratory status in patients receiving propofol sedation during PEG-procedure. Patients reporting for PEG-placement under sedation were randomized 1:1 in either standard monitoring group (SM) or capnography monitoring group including IPI (IM). Heart rate, blood pressure and arterial oxygen saturation were monitored in SM. In IM additional monitoring was performed measuring PetCO2, respiratory rate and IPI. Capnography and IPI values were recorded for all patients but were only visible to the endoscopic team for the IM-group. IPI values range between 1 and 10 (10 = normal; 8-9 = within normal range; 7 = close to normal range, requires attention; 5-6 = requires attention and may require intervention; 3-4 = requires intervention; 1-2 requires immediate intervention). Results on capnography versus standard monitoring of the same study population was published previously. A total of 147 patients (74 in SM and 73 in IM) were included in the present study. Hypoxic events occurred in 62 patients (42%) and severe hypoxic events in 44 patients (29%), respectively. Baseline characteristics were equally distributed in both groups. IPI = 1, IPI < 7 as well as the parameters PetCO2 = 0 mmHg and apnea > 10 s had a high sensitivity for hypoxic and severe hypoxic events, respectively (IPI = 1: 81%/81% [hypoxic/severe hypoxic event], IPI < 7: 82%/88%, PetCO2: 69%/68%, apnea > 10 s: 84%/84%). All four parameters had a low specificity for both hypoxic and severe hypoxic events (IPI = 1: 13%/12%, IPI < 7: 7%/7%, PetCO2: 29%/27%, apnea > 10 s: 7%/7%). In multivariate analysis, only SM and PetCO2 = 0 mmHg were independent risk factors for hypoxia. IPI (IPI = 1 and IPI < 7) as well as the individual parameters PetCO2 = 0 mmHg and apnea > 10 s allow a fast and convenient conclusion on patients' respiratory status in a morbid patient population. Sensitivity is good for most parameters, but specificity is poor. In conclusion, IPI can be a useful metric to assess respiratory status during propofol-sedation in PEG-placement. However, IPI was not superior to PetCO2 and apnea > 10 s.

Diagnostic accuracy of end-tidal carbon dioxide detection in determining correct placement of nasogastric tube: An updated systematic review with meta-analysis

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.

OBJECTIVES

To review the diagnostic accuracy of end-tidal carbon dioxide detection in determining inadvertent airway intubation and verifying correct placement of nasogastric tubes.

DESIGN

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.

Tension pneumothorax decompression with colorimetric capnography: pilot case series

Tension pneumothorax is a life-threatening condition that can develop when either the visceral pleura is disrupted, or with injury to the tracheobronchial tree. Rapid, accurate diagnosis and appropriate management are required to prevent significant atelectasis, hypoxia, circulatory arrest, and ultimate patient demise. Needle decompression is the current standard of care for the management of tension pneumothorax. Healthcare providers struggle to assess the success of decompression due to a lack of any immediate objective feedback. The gaseous composition of tension pneumothorax is similar to that of end respiratory gas. This includes an increased partial pressure of carbon dioxide in comparison to atmospheric air, which makes colorimetric capnography an ideal confirmatory test. This colorimetric capnography device may help the healthcare providers to make an objective and accurate assessment of the success of the needle decompression, in particular in prehospital environments.

Ventilation Monitoring

Ventilation or breathing is vital for life yet is not well monitored in hospital or at home. Respiratory rate is a neglected vital sign and tidal volumes together with breath sounds are checked infrequently in many patients. Medications with the potential to depress ventilation are frequently administered, and may be accentuated by obesity causing airway obstruction in the form of sleep apnea. Sepsis may adversely affect ventilation by causing an increase in respiratory rate, often a very early sign of infection. Changes in ventilation may be early signs of deterioration in the patient.

Modeling the Cost Savings of Continuous Pulse Oximetry and Capnography Monitoring of United States General Care Floor Patients Receiving Opioids Based on the PRODIGY Trial

INTRODUCTION

Despite the high incidence of respiratory depression on the general care floor and evidence that continuous monitoring improves patient outcomes, the cost-benefit of continuous pulse oximetry and capnography monitoring of general care floor patients remains unknown. This study modeled the cost and length of stay savings, investment break-even point, and likelihood of cost savings for continuous pulse oximetry and capnography monitoring of general care floor patients at risk for respiratory depression.

METHODS

A decision tree model was created to compare intermittent pulse oximetry versus continuous pulse oximetry and capnography monitoring. The model utilized costs and outcomes from the PRediction of Opioid-induced respiratory Depression In patients monitored by capnoGraphY (PRODIGY) trial, and was applied to a modeled cohort of 2447 patients receiving opioids per median-sized United States general care floor annually.

RESULTS

Continuous pulse oximetry and capnography monitoring of high-risk patients is projected to reduce annual hospital cost by $535,531 and cumulative patient length of stay by 103 days. A 1.5% reduction in respiratory depression would achieve a break-even investment point and justify the investment cost. The probability of cost saving is ≥ 80% if respiratory depression is decreased by ≥ 17%. Expansion of continuous monitoring to high- and intermediate-risk patients, or to all patients, is projected to reach a break-even point when respiratory depression is reduced by 2.5% and 3.5%, respectively, with a ≥ 80% probability of cost savings when respiratory depression decreases by ≥ 27% and ≥ 31%, respectively.

CONCLUSION

Compared to intermittent pulse oximetry, continuous pulse oximetry and capnography monitoring of general care floor patients receiving opioids has a high chance of being cost-effective.

TRIAL REGISTRATION

www.clinicaltrials.gov , Registration ID: NCT02811302.

Comparisons of the efficiency of respiratory rate monitoring devices and acoustic respiratory sound during endoscopic submucosal dissection

During moderate sedation for gastrointestinal endoscopic submucosal dissection (ESD), monitoring of ventilatory function is recommended. We compared the following techniques of respiratory rate (RR) measurement with respiratory sound (RRa): capnography (RRc), thoracic impedance (RRi), and plethysmograph (RRp). This study enrolled patients aged ≥ 20 years who underwent esophageal (n = 19) and colorectal (n = 5) ESDs. RRc, RRi, RRp, and RRa were measured by Capnostream™ 20P, BSM-2300, Nellcor™ PM1000N, and Radical-7^®, respectively. In total, 413 RR data were collected from the esophageal ESD group and 114 RR data were collected from the colorectal ESD group. Compared with RRa during colorectal ESD, that during esophageal ESD had larger bias [95% limit of agreement (LOA)] with RRc [1.9 (- 11.0-14.8) vs. - 0.4 (- 2.9-2.2)], RRi [9.4 (- 16.8-9.4) vs. - 1.5 (- 12.0-8.9)], and RRp [0.3 (- 5.7-6.4) vs. 0.2 (- 3.2-3.6)]. Of the correct RR values displayed during esophageal ESD, > 90% were measured as RRa and RRp. Moreover, RRc was a useful parameter during colorectal ESD. To maximize patient safety during ESD under sedation, endoscopists and medical staff should know the feature and principle of the devices used for RR measurement. During esophageal ESD, RRa and RRp may be a good parameter to detect bradypnea or apnea. RRc, RRa and RRp are useful for reliable during colorectal ESD.Trial registration UMIN-CTR (UMIN000025421).

Use of capnography for prediction of obstruction severity in non-intubated COPD and asthma patients

BACKGROUND

Capnography waveform contains essential information regarding physiological characteristics of the airway and thus indicative of the level of airway obstruction. Our aim was to develop a capnography-based, point-of-care tool that can estimate the level of obstruction in patients with asthma and COPD.

METHODS

Two prospective observational studies conducted between September 2016 and May 2018 at Rabin Medical Center, Israel, included healthy, asthma and COPD patient groups. Each patient underwent spirometry test and continuous capnography, as part of, either methacholine challenge test for asthma diagnosis or bronchodilator reversibility test for asthma and COPD routine evaluation. Continuous capnography signal, divided into single breaths waveforms, were analyzed to identify waveform features, to create a predictive model for FEV1 using an artificial neural network. The gold standard for comparison was FEV1 measured with spirometry.

MEASUREMENTS AND MAIN RESULTS

Overall 160 patients analyzed. Model prediction included 32/88 waveform features and three demographic features (age, gender and height). The model showed excellent correlation with FEV1 (R = 0.84), R² achieved was 0.7 with mean square error of 0.13.

CONCLUSION

In this study we have developed a model to evaluate FEV1 in asthma and COPD patients. Using this model, as a point-of-care tool, we can evaluate the airway obstruction level without reliance on patient cooperation. Moreover, continuous FEV1 monitoring can identify disease fluctuations, response to treatment and guide therapy.

TRIAL REGISTRATION

clinical trials.gov, NCT02805114. Registered 17 June 2016, https://clinicaltrials.gov/ct2/show/NCT02805114.

Use of supraglottic airway devices under capnography monitoring during cardiopulmonary resuscitation: A systematic review

BACKGROUND

Bag-valve-mask ventilation is the most commonly applied method during cardiopulmonary resuscitation. Globally, advanced airway management with blind insertion devices such as supraglottic airway devices has been implemented for years by different emergency services. The efficiency of ventilation via such devices could be measured by capnography.

OBJECTIVE

The objective of this study was to determine whether capnography is useful in patients undergoing cardiopulmonary resuscitation and to assess the effectiveness of ventilation via supraglottic airway devices.

REVIEW METHODS USED

This is a systematic review written following the steps of Preferred Reporting Items for Systematic Review and Meta-analyses protocols.

DATA SOURCES

A bibliographic search was carried out from the following databases: EBSCOhost, Scopus, EMBASE, Virtual Health Library, PubMed, Cochrane Library, Spanish Medical Index, Spanish Bibliographic Index in Health Sciences, and Latin American and Caribbean Health Sciences Literature, from inception until September 2019.

REVIEW METHODS

Studies describing the use of capnography with supraglottic airway devices during cardiopulmonary resuscitation manoeuvres were selected and evaluated using the Critical Appraisal Skills Programme.

RESULTS

Twenty-four articles were identified by title and abstract: six were randomised clinical trials, 11 were nonrandomised clinical trials, six were descriptive prospective studies, and one was a descriptive retrospective study. Nine primary research articles were selected for synthesis. Only one provided objective values of capnography obtained with ventilation with these devices, correlating them with the results of resuscitation.

CONCLUSIONS

The evidence published so far is scarce, mostly from observational studies with high risk of bias in general. Although a degree of recommendation cannot be established, some results indicate that capnography has the potential to facilitate advanced clinical practice of ventilation with supraglottic airway devices during cardiopulmonary resuscitation.

Capillary blood gas in infants with bronchiolitis: Can end-tidal capnography replace it?

OBJECTIVES

To explore the predictive ability of capillary blood gas (CBG) pCO₂ for respiratory decompensation in infants aged ≤6 months with bronchiolitis admitted from the emergency department; to determine whether end-tidal CO₂ (etCO₂) capnography can serve as a less invasive substitute for CBG pCO₂.

STUDY DESIGN

This was a prospective cohort study of previously healthy infants aged ≤6 months admitted for bronchiolitis from the emergency department (ED). Initial CBG pCO₂ and etCO₂ capnography were obtained in the ED prior to inpatient admission. Simple logistic regression modeling was used to examine the associations of CBG pCO₂ and etCO₂ capnography with respiratory decompensation. Pearson's correlation measured the relationship between CBG pCO₂ and etCO₂ capnography.

RESULTS

Of 134 patients, 61 had respiratory decompensation. There was a significant association between CBG pCO₂ and respiratory decompensation (OR = 1.07, p = 0.003), even after outlying values were excluded (OR = 1.06, p = 0.005). End tidal CO₂ capnography was not significantly associated with decompensation (OR = 1.02, p = 0.17), even after outlying values were excluded (OR = 1.02, p = 0.24). There was a moderate correlation between etCO₂ capnography and CBG pCO₂ (r = 0.39, p < 0.001).

CONCLUSION

In infants with bronchiolitis, CBG pCO₂ provides an objective measure for predicting respiratory decompensation, and a single etCO₂ measurement should not replace its use.

[The end-tidal carbon dioxide as an early sign and predictor of the return of spontaneous circulation during out-of-hospital cardiac arrest. A systematic review.]

BACKGROUND

There is no clear evidence on the maximum level of end-tidal carbon dioxide (ETCO₂) predictor of the return of spontaneous circulation (RSC) after an out-of-hospital cardiorespiratory arrest. The aims of this work was to synthesise and analyse the available evidence on the usefulness of monitoring values ETCO₂ in an out-of-hospital cardiorespiratory arrest as an early sign and prognostic indicator of the RSC.

METHODS

Systematic review, with narrative synthesis of the results, of primary studies published in English or Spanish was conducted in Medline, CINAHL, Web of Science, EMBASE, Proquest, Scopus, Cochrane, ÍnDICEs CSIC and CUIDEN of studies that analyse the usefulness of monitoring of the level of ETCO₂ as a sign of the RSC after an out-of-hospital cardiorespiratory arrest. PRISMA declaration was followed. The risk of bias was assessed with the Newcastle-Ottawa Scale.

RESULTS

1,011 studies were found, eight of which fulfilled the inclusion criteria. The studies reported an association between the abrupt increase in ETCO₂ and RSC to disagree on the predictive cut-off points (an increase than 10 mmHg and initial values or three minutes greater than 10 mmHg or 19 mmHg). The studies were of moderate to high methodological quality.

CONCLUSIONS

ETCO₂ values correlate with the RSC in adults with cardiorespiratory arrest and could predict non-survival, so they should be incorporated into advanced life support algorithms and Utstein-style reports.

Comparison of ETCO2 Value and Blood Gas PCO2 Value of Patients Receiving Non-invasive Mechanical Ventilation Treatment in Emergency Department

Capnography is the non-invasive measurement and graphic representation of the partial pressure of CO2 in expiration. Although there are many studies in the literature comparing the partial pressure of carbon dioxide (pCO2) and end-tidal CO2 (ETCO2) values in patients who underwent IMV (invasive mechanical ventilation), there are no studies showing their interchangeable applicability in patients who received NIMV (non-IMV). We aimed to evaluate whether the use of ETCO2 in the treatment process can replace pCO2 use in patients scheduled for NIMV treatment in the emergency department. Patients who applied to the emergency department with respiratory distress between March 2019 and January 2020, who were diagnosed with acute cardiogenic edema or acute chronic obstructive pulmonary disease (COPD) exacerbation, and who needed NIMV were included in the study. General characteristics of the patients and the pCO2 and ETCO2 values were measured in the blood gas 1 h after the NIMV application was started. 64.2% (99 patients) of the patients included in the study were male, and 35.8% (55 patients) were female. The mean age of the patients included in the study was 69.1 ± 12.2 years. The mean pCO2 values ​​were measured as 52.6 ± 13.2. The mean of ETCO2 values ​​measured simultaneously was 33.6 ± 10.1. There was a significant difference between the controlled pCO2 values ​​and ETCO2 values ​​at the first hour of NIMV treatment (Z: - 10.640, p < 0.001). The ETCO2 level was found to be different in our patients who received NIMV treatment, which could not be used instead of the pCO2 level.

Use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing volunteers

OBJECTIVE

The use of noninvasive volume assessment methods to predict acute blood loss in spontaneously breathing patients remains unclear. We aimed to investigate changes in the pleth variability index (PVI), vena cava collapsibility index (VCCI), end-tidal carbon dioxide (EtCO2), pulse pressure (PP), and mean arterial pressure (MAP) in spontaneously breathing volunteers after acute loss of 450 mL blood and passive leg raise (PLR).

METHODS

This prospective observational study enrolled healthy volunteers in the blood donation center of an academic hospital. We measured the PVI, EtCO2, VCCI, MAP, and PP before blood donation; at the 0th and 10th minute of blood donation; and after PLR. The primary outcome was the changes in PVI, EtCO2, VCCI, MAP, and PP.

RESULTS

We enrolled thirty volunteers. There were significant differences among the four obtained measurements of the PVI, EtCO2, and MAP (P<0.001, P<0.001, P<0.001, respectively). Compared to the predonation values, post-hoc analysis revealed an increase in the PVI at the 0th min postdonation (mean difference [MD], 5.4±5.9; 95% confidence interval [CI], -7.6 to -3.1; P<0.001); a decrease in the EtCO2 and MAP at the 0th and 10th minute postdonation, respectively (MD, 2.4±4.6; 95% CI, 0.019 to 4.84; P=0.008 and MD, 6.4±6.4; 95% CI, 3 to 9.7; P<0.001, respectively). Compared with EtCO2 at the 10th minute, the value increased after PLR (MD, 1.8±3.2; 95% CI, 0.074 to 4.44; P=0.006).

CONCLUSION

The PVI and EtCO2 could detect early hemodynamic changes after acute blood loss. However, it remains unclear whether they can determine volume status in spontaneously breathing patients.

Arterial and end-tidal carbon dioxide partial pressure difference during prehospital anaesthesia in critically ill patients

BACKGROUND

Normoventilation is crucial for many critically ill patients. Ventilation is routinely guided by end-tidal capnography during prehospital anaesthesia, based on the assumption of the gap between arterial partial pressure of carbon dioxide (PaCO2 ) and end-tidal carbon dioxide partial pressure (PetCO2 ) of approximately 0.5 kPa (3.8 mmHg).

METHODS

We retrospectively analysed the airway registry and patient chart data of patients who had been anaesthetised and intubated endotracheally by the prehospital critical care team and had their prehospital arterial blood gases analysed. Bland-Altman analysis was used to estimate the bias and limits of agreement.

RESULTS

Altogether 502 patients were included in the study, with a median age of 58 years. The most common patient groups were post-resuscitation (155, 31%), neurological emergencies (96, 19%), intoxication (75, 15%) and trauma (68, 14%). The median of the gap between PaCO2 and PetCO2 was 1.3 kPa (interquartile range 0.7 to 2.2) (9.8 (5.3-16.5) mmHg). Mean bias of PetCO2 was -1.6 kPa/12.0 mmHg (standard deviation 1.7 kPa/12.8 mmHg) with 95% confidence limits of agreement -4.9 to 1.9 kPa (-36.8 to 14.3 mmHg). The gap was ≥ 1.0 kPa (>7.5 mmHg) in 297 (66%, 95% confidence interval 55 to 63) patients.

CONCLUSION

Our results suggest that end-tidal capnography alone might not be an adequate method to achieve normoventilation for critically ill patients intubated and mechanically ventilated in prehospital setting. Thus, an arterial blood gas analysis might be useful to recognize patients with an increased gap between PaCO2 and PetCO2 .