Capnography Accurately Detects Apnea During Monitored Anesthesia Care

New acoustic monitoring system quantifying aspiration risk during monitored anaesthesia care

Respiratory monitoring is crucial during monitored anaesthesia care (MAC) to ensure patient safety. Patients undergoing procedures like gastrointestinal endoscopy and dental interventions under MAC have a heightened risk of aspiration. Despite the risks, no current system or device can evaluate aspiration risk. This study presents a novel acoustic monitoring system designed to detect fluid retention in the upper airway during MAC. We conducted a prospective observational study with 60 participants undergoing dental treatment under MAC. We utilized a prototype acoustic monitoring system to assess fluid retention in the upper airway by analysing inspiratory sounds. Water was introduced intraorally in participants to simulate fluid retention; artificial intelligence (AI) analysed respiratory sounds pre and post-injection. We also compared respiratory sounds pre-treatment and during coughing events. Coughing was observed in 14 patients during MAC, and 31 instances of apnoea were detected by capnography. However, 27 of these cases had breath sounds. Notably, with intraoral water injection, the Stridor Quantitative Value (STQV) significantly increased; furthermore, the STQV was substantially higher immediately post-coughing in patients who coughed during MAC. In summary, the innovative acoustic monitoring system using AI provides accurate evaluations of fluid retention in the upper airway, offering potential to mitigate aspiration risks during MAC.Clinical trial number: jRCTs 062220054.

Breathing-Associated Facial Region Segmentation for Thermal Camera-Based Indirect Breathing Monitoring

Breathing can be measured in a non-contact method using a thermal camera. The objective of this study investigates non-contact breathing measurements using thermal cameras, which have previously been limited to measuring the nostril only from the front where it is clearly visible. The previous method is challenging to use for other angles and frontal views, where the nostril is not well-represented. In this paper, we defined a new region called the breathing-associated-facial-region (BAFR) that reflects the physiological characteristics of breathing, and extract breathing signals from views of 45 and 90 degrees, including the frontal view where the nostril is not clearly visible. Experiments were conducted on fifteen healthy subjects in different views, including frontal with and without nostril, 45-degree, and 90-degree views. A thermal camera (A655sc model, FLIR systems) was used for non-contact measurement, and biopac (MP150, Biopac-systems-Inc) was used as a chest breathing reference. The results showed that the proposed algorithm could extract stable breathing signals at various angles and views, achieving an average breathing cycle accuracy of 90.9% when applied compared to 65.6% without proposed algorithm. The average correlation value increases from 0.587 to 0.885. The proposed algorithm can be monitored in a variety of environments and extract the BAFR at diverse angles and views.

Advances in Analgosedation and Periprocedural Care for Gastrointestinal Endoscopy

The number and complexity of endoscopic gastrointestinal diagnostic and therapeutic procedures is globally increasing. Procedural analgosedation during gastrointestinal endoscopic procedures has become the gold standard of gastrointestinal endoscopies. Patient satisfaction and safety are important for the quality of the technique. Currently there are no uniform sedation guidelines and protocols for specific gastrointestinal endoscopic procedures, and there are several challenges surrounding the choice of an appropriate analgosedation technique. These include categories of patients, choice of drug, appropriate monitoring, and medical staff providing the service. The ideal analgosedation technique should enable the satisfaction of the patient, their maximum safety and, at the same time, cost-effectiveness. Although propofol is the gold standard and the most used general anesthetic for endoscopies, its use is not without risks such as pain at the injection site, respiratory depression, and hypotension. New studies are looking for alternatives to propofol, and drugs like remimazolam and ciprofol are in the focus of researchers' interest. New monitoring techniques are also associated with them. The optimal technique of analgosedation should provide good analgesia and sedation, fast recovery, comfort for the endoscopist, patients' safety, and will have financial benefits. The future will show whether these new drugs have succeeded in these goals.

Case report: The art of anesthesiology-Approaching a minor procedure in a child with MPI-CDG

Background: Protein glycosylation plays an important role in post-translational modification, which defines a broad spectrum of protein functions. Accordingly, infants with a congenital disorder of glycosylation (CDG) can have N-glycosylation, O-glycosylation, or combined N- and O-glycosylation defects, resulting in similar but different multisystem involvement. CDGs can present notable gastrointestinal and neurologic symptoms. Both protein-losing enteropathy and hypotonia affect the decision of using anesthetics. We reported a case of MPI-CDG with protein-losing enteropathy and muscular hypotonia that underwent different anesthesia approach strategies of vascular access. Here, we highlight why intubation with sevoflurane anesthesia and sparing use of muscle relaxants is the optimal strategy for such a condition. Case presentation: A 25-month-old girl, weighing 6.6 kg and 64 cm tall, suffered chronic diarrhea, hypoalbuminemia, and hypotonia since birth. Protein-losing enteropathy due to MPI-CDG was documented by whole-exome sequencing. She underwent three sedated surgical procedures in our hospital. The sedation was administered twice by pediatricians with oral chloral hydrate, intravenous midazolam, and ketamine, to which the patient showed moderate to late recovery from sedation and irritability the following night. The most recent one was administered by an anesthesiologist, where endotracheal intubation was performed with sevoflurane as the main anesthetic. The patient regained consciousness immediately after the operation. She had no complications after all three sedation/anesthesia interventions and was discharged 7 days later, uneventful after the third general anesthesia procedure. Conclusion: We performed safe anesthetic management in a 25-month-old girl with MPI-CDG using sevoflurane under controlled ventilation. She awoke immediately after the procedure. Due to the disease entity, we suggested bypassing the intravenous route to avoid excess volume for drug administration and that muscle relaxant may not be necessary for endotracheal intubation and patient immobilization when performing procedures under general anesthesia in CDG patients.

Thermodiluted relative tidal volume estimation using a thermal camera in operating room under spinal anesthesia

Background

Estimating relative tidal volume is an important factor when monitoring breathing status. The relationship between temperature and respiration volume has rarely been studied. In this paper, a formula was derived for calculating thermodiluted respiration volume from temperature changes in the nasal cavity. To evaluate the proposed formula, the study compared the relative tidal volume estimated by the proposed formula with that recorded by a respiration volume monitor (Exspiron1Xi, RVM). Thermal data were obtained for 8 cases at a rate of 10 measurements per second. Simultaneous recordings by the RVM are regarded as the reference.

Results

The mean of ICC coefficient is 0.948 ± 0.030, RMSE is 0.1026 ± 0.0284, R-squared value is 0.8962 ± 0.065 and linear regression coefficient \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\mathrm{\alpha }$$\end{document}α is 0.966 ± 0.104, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\upbeta$$\end{document}β is 0.042 ± 0.057. Bland–Altman plot showed 96.01% of samples that the difference between the measured and estimated values exists within 2 standard deviations.

Conclusions

In this paper, a model that can thermodynamically calculate the relationship between thermal energy and respiration volume is proposed. The thermodiluted model is a feasible method for estimating relative respiration tidal volumes.

Anesthesia for digestive tract endoscopy

PURPOSE OF REVIEW

Nonoperating room anesthesia for digestive tract endoscopy has its own specificities and requires practical training. Monitoring devices, anesthetic drugs, understanding of procedures and management of complications are critical aspects.

RECENT FINDINGS

New data are available regarding risk factors for intra- and postoperative complications (based on anesthesia registries), airway management, new anesthetic drugs, techniques of administration and management of advances in interventional endoscopy procedures.

SUMMARY

Digestive tract endoscopy is a common procedure that takes place outside the operating room most of the time and has become more and more complex due to advanced invasive procedures. Prior evaluation of the patient's comorbidities and a good understanding of the objectives and constraints of the endoscopic procedures are required. Assessing the risk of gastric content aspiration is critical for determining appropriate anesthetic protocols. The availability of adequate monitoring (capnographs adapted to spontaneous ventilation, bispectral index), devices for administration of anesthetic/sedative agents (target-controlled infusion) and oxygenation (high flow nasal oxygenation) guarantees the quality of sedation and patient' safety during endoscopic procedures. Knowledge of the specificities of each interventional endoscopic procedure (endoscopic retrograde cholangiopancreatography, submucosal dissection) allows preventing complications during anesthesia.

Assessment of Cardio-Respiratory Function in Overweight and Obese Children Wearing Face Masks during the COVID-19 Pandemic

OBJECTIVE

To evaluate whether the use of a surgical and N95 mask for overweight and obese children was associated with respiratory distress.

METHODS

We enrolled 15 healthy and 14 overweight or obese children. We performed two sessions: one wearing a surgical, the other an N95 mask. We tracked changes in partial pressure of end-tidal carbon dioxide (PETCO2), oxygen saturation (SaO2), pulse rate (PR), and respiratory rate (RR) during a 72 min test: 30 min without a mask, 30 min wearing a mask, and then during a 12 min walking test.

RESULTS

In healthy children, there was no significant change in SaO2 and PETCO2 during the study; there was a significant increase in PR and RR after the walking test with both the masks. In overweight or obese children, there was no significant change in SaO2 during the study period; there was a significant increase in PETCO2 as fast as wearing the mask and an increase in PETCO2, PR, and RR after walking test. After the walking test, we showed a significant correlation between PETCO2 and body mass index.

CONCLUSION

Overweight or Obese children who wear a mask are more prone to developing respiratory distress, which causes them to remove it frequently. In a crowded environment, they are at greater risk of infection. For this reason, it is desirable that they attend environments where everyone uses a mask.

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.

Effects of N95 Mask Use on Pulmonary Function in Children

OBJECTIVE

To assess whether use of an N95 mask by children is associated with episodes of desaturation or respiratory distress.

STUDY DESIGN

Twenty-two healthy children were assigned at random to 1 of 2 groups: one group wearing N95 masks without an exhalation valve and the other group wearing N95 masks with an exhalation valve. We tracked changes in partial pressure of end-tidal carbon dioxide (P_ETCO2), oxygen saturation, pulse rate, and respiratory rate over 72 minutes of mask use. All subjects were monitored every 15 minutes, the first 30 minutes while not wearing a mask and the next 30 minutes while wearing a mask. They then performed a 12-minute walking test.

RESULTS

The children did not experience a statistically significant change in oxygen saturation or pulse rate during the study. There were significant increases in respiratory rate and P_ETCO2 in the children wearing an N95 mask without an exhalation valve, whereas these increases were seen in the children wearing a mask with an exhalation valve only after the walking test.

CONCLUSIONS

The use of an N95 mask could potentially cause breathing difficulties in children if the mask does not have an exhalation valve, particularly during a physical activity. We believe that wearing a surgical mask may be more appropriate for children.

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).

Assessment of Respiratory Function in Infants and Young Children Wearing Face Masks During the COVID-19 Pandemic

IMPORTANCE

Face masks have been associated with effective prevention of diffusion of viruses via droplets. However, the use of face masks among children, especially those aged younger than 3 years, is debated, and the US Centers for Disease Control and American Academy of Physicians recommend the use of face mask only among individuals aged 3 years or older.

OBJECTIVE

To examine whether the use of surgical facial masks among children is associated with episodes of oxygen desaturation or respiratory distress.

DESIGN, SETTING, AND PARTICIPANTS

This cohort study was conducted from May through June 2020 in a secondary-level hospital pediatric unit in Italy. Included participants were 47 healthy children divided by age (ie, group A, aged ≤24 months, and group B, aged >24 months to ≤144 months). Data were analyzed from May through June 2020.

INTERVENTIONS

All participants were monitored every 15 minutes for changes in respiratory parameters for the first 30 minutes while not wearing a surgical face mask and for the next 30 minutes while wearing a face mask. Children aged 24 months and older then participated in a walking test for 12 minutes.

MAIN OUTCOMES AND MEASURES

Changes in respiratory parameters during the use of surgical masks were evaluated.

RESULTS

Among 47 children, 22 children (46.8%) were aged 24 months or younger (ie, group A), with 11 boys (50.0%) and median (interquartile range [IQR]) age 12.5 (10.0-17.5) months, and 25 children (53.2%) were aged older than 24 months to 144 months or younger, with 13 boys (52.0%) and median (IQR) age 100.0 (72.0-120.0) months. During the first 60 minutes of evaluation in the 2 groups, there was no significant change in group A in median (IQR) partial pressure of end-tidal carbon dioxide (Petco2; 33.0 [32.0-34.0] mm Hg; P for Kruskal Wallis = .59), oxygen saturation (Sao2; 98.0% [97.0%-99.0%]; P for Kruskal Wallis = .61), pulse rate (PR; 130.0 [115.0-140.0] pulsations/min; P for Kruskal Wallis = .99), or respiratory rate (RR; 30.0 [28.0-33.0] breaths/min; P for Kruskal Wallis = .69) or for group B in median (IQR) Petco2 (36.0 [34.0-38.0] mm Hg; P for Kruskal Wallis = .97), Sao2 (98.0% [97.0%-98.0%]; P for Kruskal Wallis = .52), PR (96.0 [84.0-104.5] pulsations/min; P for Kruskal Wallis test = .48), or RR (22.0 [20.0-25.0] breaths/min; P for Kruskal Wallis = .55). After the group B walking test, compared with before the walking test, there was a significant increase in median (IQR) PR (96.0 [84.0-104.5] pulsations/min vs 105.0 [100.0-115.0] pulsations/min; P < .02) and RR (22.0 [20.0-25.0] breaths/min vs 26.0 [24.0-29.0] breaths/min; P < .05).

CONCLUSIONS AND RELEVANCE

This cohort study among infants and young children in Italy found that the use of facial masks was not associated with significant changes in Sao2 or Petco2, including among children aged 24 months and younger.

Decreased CO2 Levels as Indicators of Possible Mechanical Ventilation-Induced Hyperventilation in COVID-19 Patients: A Retrospective Analysis

Background: Six months since the outbreak of coronavirus disease (COVID-19), the pandemic continues to grow worldwide, although the outbreak in Wuhan, the worst-hit area, has been controlled. Thus, based on the clinical experience in Wuhan, we hypothesized that there is a relationship between the patient's CO₂ levels and prognosis.

Methods: COVID-19 patients' information was retrospectively collected from medical records at the Leishenshan Hospital, Wuhan. Logistic and Cox regression analyses were conducted to determine the correlation between decreased CO₂ levels and disease severity or mortality risk. The Kaplan-Meier curve analysis was coupled with the log-rank test to understand COVID-19 progression in patients with decreased CO₂ levels. Curve fitting was used to confirm the correlation between computed tomography scores and CO₂ levels.

Results: Cox regression analysis showed that the mortality risk of COVID-19 patients correlated with decreased CO₂ levels. The adjusted hazard ratios for decreased CO₂ levels in COVID-19 patients were 8.710 [95% confidence interval (CI): 2.773–27.365, P < 0.001], and 4.754 (95% CI: 1.380–16.370, P = 0.013). The adjusted odds ratio was 0.950 (95% CI: 0.431–2.094, P = 0.900). The Kaplan-Meier survival curves demonstrated that patients with decreased CO₂ levels had a higher risk of mortality.

Conclusions: Decreased CO₂ levels increased the mortality risk of COVID-19 patients, which might be caused by hyperventilation during mechanical ventilation. This finding provides important insights for clinical treatment recommendations.

Nonoperating room anaesthesia: safety, monitoring, cognitive aids and severe acute respiratory syndrome coronavirus 2

PURPOSE OF REVIEW

With an ageing population, mounting pressure on the healthcare dollar, significant advances in medical technology, and now in the context of coronavirus disease 2019, the traditional paradigm in which operative procedures are undertaken is changing. Increasingly, procedures are performed in more distant, isolated and less familiar locations, challenging anaesthesiologists and requiring well developed situational awareness. This review looks at implications for the practitioner and patient safety, outlining considerations and steps involved in translation of systems and processes well established in the operating room to more unfamiliar environments.

RECENT FINDINGS

Despite limited nonoperating room anaesthesia outcome data, analysis of malpractice claims, anaesthesia-related medical disputes and clinical outcome registries have suggested higher morbidity and mortality. Complications were often associated with suboptimal monitoring, nonadherence to recommended guidelines and sedationist or nonanaesthesiologist caregivers. More recently, clear monitoring guidelines, global patient safety initiatives and widespread implementation of cognitive aids may have contributed to nonoperating room anaesthesia (NORA) outcomes approaching that of traditional operating rooms.

SUMMARY

As NORA caseloads increase, understanding structural and anaesthetic requirements is essential to patient safety. The severe acute respiratory syndrome coronavirus 2 pandemic has provided an opportunity for anaesthesiologists to implement lessons learned from previous analyses, share expertise as patient safety leaders and provide valuable input into protecting patients and caregivers.

Benefits and harms of capnography during procedures involving moderate sedation: A rapid review and meta-analysis

BACKGROUND

Patient safety is a priority in dentistry. Evaluating the benefits and harms associated with the addition of capnography to standard monitoring during moderate sedation for adult patients in the dental practice setting is needed.

TYPES OF STUDIES REVIEWED

The authors used rapid review methodology to identify relevant systematic reviews, which they updated through a systematic search by using the same search strategy as the identified reviews. The authors searched PubMed and Google Scholar and through the references of the identified systematic reviews, which yielded 2,892 studies. Inclusion criteria were that the article was available in English, was original research in adult humans who had undergone moderate procedural sedation, and involved comparing standard monitoring with the addition of capnography.

RESULTS

Sixteen studies were eligible, involving 3,866 adults undergoing procedural sedation. The authors used the Grading of Recommendations Assessment, Development and Evaluation approach to evaluate the evidence and rate it as being of moderate to low quality because of high risk of bias and heterogeneous effects for the outcomes of hypoxemia and adverse respiratory events. Capnography had higher sensitivity to detect adverse respiratory events than did standard monitoring alone (0.92; 95% confidence interval, 0.65 to 0.99) and may reduce the risk of developing hypoxemia by 31% (risk ratio, 0.69; 95% confidence interval, 0.57 to 0.82). Capnography did not affect the risk of developing serious adverse events, procedure time, sedation quality, or patient satisfaction.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

Adding capnography to standard monitoring of adults during moderate sedation may reduce the risk of developing hypoxemia, increase detection of adverse respiratory events, and is not associated with additional harms. These findings suggest routine use of capnography during moderate sedation has the potential to reduce adverse anesthetic outcomes in dental practice.

Capnography Monitoring During Procedural Sedation and Analgesia

Procedural sedation is used to alleviate pain and anxiety associated with diagnostic procedures in the acute care setting. Although commonly used, procedural sedation is not without risk. Key to reducing this risk is early identification of risk factors through presedation screening and monitoring during the procedure. Electrocardiogram, respiratory rate, blood pressure, and pulse oximetry commonly are monitored. These parameters do not reliably identify airway and ventilation compromise. Capnography measures exhaled carbon dioxide and provides early identification of airway obstruction and hypoventilation. Capnography is useful in patients receiving supplemental oxygen. In these patients, oxygen desaturation reported by pulse oximetry may lag during episodes of respiratory depression and apnea. Capnography indicates partial pressure of end-tidal carbon dioxide and provides information regarding airway integrity and patterns of ventilation compromise. Implementation of this technology may provide an additional layer of safety, reducing risk of respiratory compromise in patients receiving procedural sedation.

Capnography Monitoring for Patients Undergoing Moderate Sedation: An SGNA Fellowship Project

The purpose of this Society of Gastroenterology Nurses and Associates Fellowship project was to determine whether capnography is more accurate than oximetry in identifying symptoms of respiratory depression in patients undergoing moderate sedation. Capnography provides an early warning of respiratory depression and airway compromise, especially when the medications used for sedation include opiates and benzodiazepines. It is a standard of care according to the American Society of Anesthesiologists that should be adopted in order to provide the safest possible environment for the delivery of moderate sedation. During this project, the nursing staff were educated on the importance and usage of capnography. Evidence was gathered that helped show that by using capnography, nurses were able to identify signs of respiratory depression earlier and more frequently than with the use of oximetry and cardiac monitoring alone.

Comparing Nasal End-Tidal Carbon Dioxide Measurement Variation and Agreement While Delivering Pulsed and Continuous Flow Oxygen in Volunteers and Patients

BACKGROUND

Supplemental oxygen is administered during procedural sedation to prevent hypoxemia. Continuous flow oxygen, the most widespread method, is generally adequate but distorts capnography. Pulsed flow oxygen is novel and ideally will not distort capnography. We have developed a prototype oxygen administration system designed to try to facilitate end-tidal carbon dioxide (ETCO2) measurement. We conducted a volunteer study (ClinicalTrials.gov, NCT02886312) to determine how much nasal ETCO2 measurements vary with oxygen flow rate. We also conducted a clinical study (NCT02962570) to determine the median difference and limits of agreement between ETCO2 measurements made with and without administering oxygen.

METHODS

Both studies were conducted at the University of Utah and participants acted as their own control. Inclusion criteria were age 18 years and older with an American Society of Anesthesiologists physical status of I-III. Exclusion criteria included acute respiratory distress syndrome, pneumonia, lung or cardiovascular disease, nasal/bronchial congestion, pregnancy, oxygen saturation measured by pulse oximetry <93%, and a procedure scheduled for <20 minutes. For the volunteer study, pulsed and continuous flow was administered at rates from 2 to 10 L/min using a single sequence of technique and flow. The median absolute deviation from the median value was analyzed for the primary outcome of ETCO2. For the clinical study, ETCO2 measurements (the primary outcome) were collected while administering pulsed and continuous flow at rates between 1 and 5 L/min and were compared to measurements without oxygen flow. Due to institutional review board requirements for patient safety, this study was not randomized. After completing the study, measurements with and without administering oxygen were analyzed to determine median differences and 95% limits of agreement for each administration technique.

RESULTS

Thirty volunteers and 60 patients participated in these studies which ended after enrolling the predetermined number of participants. In volunteers, the median absolute deviation for ETCO2 measurements made while administering pulsed flow oxygen (0.89; 25%-75% quantiles: 0.3-1.2) was smaller than while administering continuous flow oxygen (3.93; 25%-75% quantiles: 2.2-6.2). In sedated patients, the median difference was larger during continuous flow oxygen (-6.8 mm Hg; 25%-75% quantiles: -12.5 to -2.1) than during pulsed flow oxygen (0.1 mm Hg; 25%-75% quantiles: -0.5 to 1.5). The 95% limits of agreement were also narrower during pulsed flow oxygen (-2.4 to 4.5 vs -30.5 to 2.4 mm Hg).

CONCLUSIONS

We have shown that nasal ETCO2 measurements while administering pulsed flow have little deviation and agree well with measurements made without administering oxygen. We have also demonstrated that ETCO2 measurements during continuous flow oxygen have large deviation and wide limits of agreement when compared with measurements made without administering oxygen.

Using continuous quantitative capnography for emergency department procedural sedation: a systematic review and cost-effectiveness analysis

End-tidal CO₂ has been advocated to improve safety of emergency department (ED) procedural sedation by decreasing hypoxia and catastrophic outcomes. This study aimed to estimate the cost-effectiveness of routine use of continuous waveform quantitative end-tidal CO₂ monitoring for ED procedural sedation in prevention of catastrophic events. Markov modeling was used to perform cost-effectiveness analysis to estimate societal costs per prevented catastrophic event (death or hypoxic brain injury) during routine ED procedural sedation. Estimates for efficacy of capnography and safety of sedation were derived from the literature. This model was then applied to all procedural sedations performed in US EDs with assumptions selected to maximize efficacy and minimize cost of implementation. Assuming that capnography decreases the catastrophic adverse event rate by 40.7% (proportional to efficacy in preventing hypoxia), routine use of capnography would decrease the 5-year estimated catastrophic event rate in all US EDs from 15.5 events to 9.2 events (difference 6.3 prevented events per 5 years). Over a 5-year period, implementing routine end-tidal CO₂ monitoring would cost an estimated $2,830,326 per prevented catastrophic event, which translates into $114,007 per quality-adjusted life-year. Sensitivity analyses suggest that reasonable assumptions continue to estimate high costs of prevented catastrophic events. Continuous waveform quantitative end-tidal CO₂ monitoring is a very costly strategy to prevent catastrophic complications of procedural sedation when applied routinely in ED procedural sedations.

Laparoscopic Sterilization Under Local Anesthesia with Conscious Sedation Versus General Anesthesia: Systematic Review of the Literature

Female sterilization is the most popular and common contraceptive method worldwide. Because hysteroscopic sterilization techniques are used less often due to side effects, the number of laparoscopic sterilization is increasing. A systematic overview concerning the most optimal anesthetic technique for laparoscopic sterilization is lacking. We performed a systematic review to compare conscious sedation with general anesthesia for laparoscopic sterilization procedures with respect to clinical relevant outcome measures, such as operating times, perioperative parameters and complications, patient comfort, recovery, and patient satisfaction. We searched Cochrane Central Register of Controlled Trials, MEDLINE, and EMBASE for randomized controlled trials comparing general anesthesia with conscious sedation for laparoscopic sterilization. Two authors (AGH and HAAMvV) abstracted and entered data into RevMan. Methodologic quality of the included trials was critically appraised. For our main outcome measures mean differences (continuous variables) and risk ratios (dichotomous variables) with 95% confidence intervals using random-effect models were calculated. Four randomized controlled trials were included comparing general anesthesia versus local anesthesia with conscious sedation for laparoscopic sterilization. The methodologic quality of the studies was moderate to good. Both techniques were comparable with regard to operating times, complications, and postoperative pain. However, local anesthesia with conscious sedation showed better results compared with general anesthesia with respect to recovery times, patient complaints of sore throat, and patient recovery and satisfaction. In conclusion, this systematic review about anesthetic techniques for laparoscopic sterilization showed that both general anesthesia and conscious sedation have no major anesthetic complications and may therefore be safe. Patients might benefit from conscious sedation in terms of recovery times, sore throat, and patient recovery and satisfaction, but only a few studies are included in the review and are relatively old. New research regarding this subject is needed to advise our patients most optimally in the future about the best anesthetic technique to be used when choosing for a laparoscopic sterilization procedure.

Capnography in the Emergency Department: A Review of Uses, Waveforms, and Limitations

BACKGROUND

Capnography has many uses in the emergency department (ED) and critical care setting, most commonly cardiac arrest and procedural sedation.

OBJECTIVE OF THE REVIEW

This review evaluates several indications concerning capnography beyond cardiac arrest and procedural sedation in the ED, as well as limitations and specific waveforms.

DISCUSSION

Capnography includes the noninvasive measurement of CO₂, providing information on ventilation, perfusion, and metabolism in intubated and spontaneously breathing patients. Since the 1990s, capnography has been utilized extensively for cardiac arrest and procedural sedation. Qualitative capnography includes a colorimetric device, changing color on the amount of CO₂ present. Quantitative capnography provides a numeric value (end-tidal CO₂), and capnography most commonly includes a waveform as a function of time. Conditions in which capnography is informative include cardiac arrest, procedural sedation, mechanically ventilated patients, and patients with metabolic acidemia. Patients with seizure, trauma, and respiratory conditions, such as pulmonary embolism and obstructive airway disease, can benefit from capnography, but further study is needed. Limitations include use of capnography in conditions with mixed pathophysiology, patients with low tidal volumes, and equipment malfunction. Capnography should be used in conjunction with clinical assessment.

CONCLUSIONS

Capnography demonstrates benefit in cardiac arrest, procedural sedation, mechanically ventilated patients, and patients with metabolic acidemia. Further study is required in patients with seizure, trauma, and respiratory conditions. It should only be used in conjunction with other patient factors and clinical assessment.

Life-threatening perioperative anesthetic complications: major issues surrounding perioperative morbidity and mortality

Perioperative morbidity and mortality related to anesthesia involves multiple factors. Patient characteristics and comorbidities play a role in many of these events, highlighting the importance of preoperative screening. While optimization of patient comorbidities is not always possible, having data regarding those comorbidities can prove life-saving. Equipment and medication considerations also enter into untoward outcomes such as anesthetic interventions outside of the traditional operating room where resources are sometimes lacking and haste creates errors. Ultimately, when surgeons and anesthesiologists cooperate in patient care, communicating concisely but thoroughly, patients are more likely to do well. The language of surgeons is that of diagnosis requiring a surgical intervention, while anesthesiologists are discussing patient comorbidities impacted by anesthetic medications, positive pressure ventilation, neuraxial techniques, ramifications of patient positioning, effects of opiates and so on. Because all of the considerations combine in determining outcomes, it is incumbent on both surgeons and anesthesiologists to understand those elements leading to severe morbid events as well as death. This review touches on many of the most important factors.

Capnography monitoring the hypoventilation during the induction of bronchoscopic sedation: A randomized controlled trial

We hypothesize that capnography could detect hypoventilation during induction of bronchoscopic sedation and starting bronchoscopy following hypoventilation, may decrease hypoxemia. Patients were randomized to: starting bronchoscopy when hypoventilation (hypopnea, two successive breaths of at least 50% reduction of the peak wave compared to baseline or apnea, no wave for 10 seconds) (Study group, n = 55), or when the Observer Assessment of Alertness and Sedation scale (OAAS) was less than 4 (Control group, n = 59). Propofol infusion was titrated to maintain stable vital signs and sedative levels. The hypoventilation during induction in the control group and the sedative outcome were recorded. The patient characteristics and procedures performed were similar. Hypoventilation was observed in 74.6% of the patients before achieving OAAS < 4 in the control group. Apnea occurred more than hypopnea (p < 0.0001). Hypoventilation preceded OAAS < 4 by 96.5 ± 88.1 seconds. In the study group, the induction time was shorter (p = 0.03) and subjects with any two events of hypoxemia during sedation, maintenance or recovery were less than the control group (1.8 vs. 18.6%, p < 0.01). Patient tolerance, wakefulness during sedation, and cooperation were similar in both groups. Significant hypoventilation occurred during the induction and start bronchoscopy following hypoventilation may decrease hypoxemia without compromising patient tolerance.

Patient safety during procedural sedation using capnography monitoring: a systematic review and meta-analysis

OBJECTIVE

To evaluate the effect of capnography monitoring on sedation-related adverse events during procedural sedation and analgesia (PSA) administered for ambulatory surgery relative to visual assessment and pulse oximetry alone.

DESIGN AND SETTING

Systematic literature review and random effects meta-analysis of randomised controlled trials (RCTs) reporting sedation-related adverse event incidence when adding capnography to visual assessment and pulse oximetry in patients undergoing PSA during ambulatory surgery in the hospital setting. Searches for eligible studies published between 1 January 1995 and 31 December 2016 (inclusive) were conducted in PubMed, the Cochrane Library and EMBASE without any language constraints. Searches were conducted in January 2017, screening and data extraction were conducted by two independent reviewers, and study quality was assessed using a modified Jadad scale.

INTERVENTIONS

Capnography monitoring relative to visual assessment and pulse oximetry alone.

PRIMARY AND SECONDARY OUTCOME MEASURES

Predefined endpoints of interest were desaturation/hypoxaemia (the primary endpoint), apnoea, aspiration, bradycardia, hypotension, premature procedure termination, respiratory failure, use of assisted/bag-mask ventilation and death during PSA.

RESULTS

The literature search identified 1006 unique articles, of which 13 were ultimately included in the meta-analysis. Addition of capnography to visual assessment and pulse oximetry was associated with a significant reduction in mild (risk ratio (RR) 0.77, 95% CI 0.67 to 0.89) and severe (RR 0.59, 95% CI 0.43 to 0.81) desaturation, as well as in the use of assisted ventilation (OR 0.47, 95% CI 0.23 to 0.95). No significant differences in other endpoints were identified.

CONCLUSIONS

Meta-analysis of 13 RCTs published between 2006 and 2016 showed a reduction in respiratory compromise (from respiratory insufficiency to failure) during PSA with the inclusion of capnography monitoring. In particular, use of capnography was associated with less mild and severe oxygen desaturation, which may have helped to avoid the need for assisted ventilation.

Research: Continuous Surveillance of Sleep Apnea Patients in a Medical-Surgical Unit

This report consists of two separate studies on the use of continuous capnography monitoring conducted in an effort to improve patient safety at Virtua Health System. The desire for improved patient safety is motivating continuous monitoring and improved surveillance in clinical areas not traditionally equipped for such monitoring. We explored the use of remote monitoring of capnography, using enterprise middleware, in patients recovering from surgery in a medical-surgical unit. Continuous monitoring traditionally has been used in higher-acuity settings, such as intensive care units. Patients diagnosed or suspected to have obstructive or central sleep apnea may benefit from the increased surveillance afforded by continuous monitoring. Pain management in this cohort of patients, recovering from bariatric, joint replacement, or other major surgery, often involves administration of opioids (e.g., hydromorphone, morphine sulfate), which are known to increase risk of respiratory depression. Continuous monitoring of these patients increases the likelihood of detecting adverse clinical events. Our goal was to implement continuous monitoring in order to identify alarm conditions caused by adverse clinical events requiring intervention (e.g., opioid-induced respiratory depression) and artifacts related to patient movement, suspect measurements, or other medical device-generated alarm signals.

Estimation of breathing rate in thermal imaging videos: a pilot study on healthy human subjects

Diverse studies have demonstrated the importance of monitoring breathing rate (BR). Commonly, changes in BR are one of the earliest and major markers of serious complications/illness. However, it is frequently neglected due to limitations of clinically established measurement techniques, which require attachment of sensors. The employment of adhesive pads or thoracic belts in preterm infants as well as in traumatized or burned patients is an additional paramount issue. The present paper proposes a new robust approach, based on data fusion, to remotely monitor BR using infrared thermography (IRT). The algorithm considers not only temperature modulation around mouth and nostrils but also the movements of both shoulders. The data of these four sensors/regions of interest need to be further fused to reach improved accuracy. To investigate the performance of our approach, two different experiments (phase A: normal breathing, phase B: simulation of breathing disorders) on twelve healthy volunteers were performed. Thoracic effort (piezoplethysmography) was simultaneously acquired to validate our results. Excellent agreements between BR estimated with IRT and gold standard were achieved. While in phase A a mean correlation of 0.98 and a root-mean-square error (RMSE) of 0.28 bpm was reached, in phase B the mean correlation and the RMSE hovered around 0.95 and 3.45 bpm, respectively. The higher RMSE in phase B results predominantly from delays between IRT and gold standard in BR transitions: eupnea/apnea, apnea/tachypnea etc. Moreover, this study also demonstrates the capability of IRT to capture varied breathing disorders, and consecutively, to assess respiratory function. In summary, IRT might be a promising monitoring alternative to the conventional contact-based techniques regarding its performance and remarkable capabilities.

Advanced Monitoring Is Associated with Fewer Alarm Events During Planned Moderate Procedure-Related Sedation: A 2-Part Pilot Trial

Supplemental Digital Content is available in the text.

Published ahead of print February 1, 2016

Diagnostic and interventional procedures are often facilitated by moderate procedure-related sedation. Many studies support the overall safety of this sedation; however, adverse cardiovascular and respiratory events are reported in up to 70% of these procedures, more frequently in very young, very old, or sicker patients. Monitoring with pulse oximetry may underreport hypoventilation during sedation, particularly if supplemental oxygen is provided. Capnometry may result in false alarms during sedation when patients mouth breathe or displace sampling devices. Advanced monitor use during sedation may allow event detection before complications develop. This 2-part pilot study used advanced monitors during planned moderate sedation to (1) determine incidences of desaturation, low respiratory rate, and deeper than intended sedation alarm events; and (2) determine whether advanced monitor use is associated with fewer alarm events.

Monitored anesthesia care in and outside the operating room

Monitored anesthesia care (MAC) is an anesthesia technique combining local anesthesia with parenteral drugs for sedation and analgesia. The use of MAC is increasing for a variety of diagnostic and therapeutic procedures in and outside of the operating room due to the rapid postoperative recovery with the use of relatively small amounts of sedatives and analgesics compared to general anesthesia. The purposes of MAC are providing patients with safe sedation, comfort, pain control and satisfaction. Preoperative evaluation for patients with MAC is similar to those of general or regional anesthesia in that patients should be comprehensively assessed. Additionally, patient cooperation with comprehension of the procedure is an essential component during MAC. In addition to local anesthesia by operators or anesthesiologists, systemic sedatives and analgesics are administered to provide patients with comfort during procedures performed with MAC. The discretion and judgment of an experienced anesthesiologist are required for the safety and efficacy profiles because the airway of the patients is not secured. The infusion of sedatives and analgesics should be individualized during MAC. Many procedures in and outside of the operating room, including eye surgery, otolaryngologic surgery, cardiovascular procedures, pain procedures, and endoscopy are performed with MAC to increase patient and operator satisfaction.

Safe sedation for the non-anaesthetist

Sedation has become an essential part of many invasive medical procedures. However, over the years, there have been concerns about the safety of sedation techniques. Various combinations of drug-based and non-drug-based approaches are used for procedural sedation depending on patient factors and the anticipated discomfort associated with each procedure. The common denominator for successful practice for a sedationist is knowledge, adequate training and a mechanism for revalidation.

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 (SaO2<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 mmHg or <85 mmHg if baseline <100 mmHg) 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.

An Ethnographic Observational Study to Evaluate and Optimize the Use of Respiratory Acoustic Monitoring in Children Receiving Postoperative Opioid Infusions

BACKGROUND

Respiratory depression in children receiving postoperative opioid infusions is a significant risk because of the interindividual variability in analgesic requirement. Detection of respiratory depression (or apnea) in these children may be improved with the introduction of automated acoustic respiratory rate (RR) monitoring. However, early detection of adverse events must be balanced with the risk of alarm fatigue. Our objective was to evaluate the use of acoustic RR monitoring in children receiving opioid infusions on a postsurgical ward and identify the causes of false alarm and optimal alarm thresholds.

METHODS

A video ethnographic study was performed using an observational, mixed methods approach. After surgery, an acoustic RR sensor was placed on the participant's neck and attached to a Rad87 monitor. The monitor was networked with paging for alarms. Vital signs data and paging notification logs were obtained from the central monitoring system. Webcam videos of the participant, infusion pump, and Rad87 monitor were recorded, stored on a secure server, and subsequently analyzed by 2 research nurses to identify the cause of the alarm, response, and effectiveness. Alarms occurring within a 90-second window were grouped into a single-alarm response opportunity.

RESULTS

Data from 49 patients (30 females) with median age 14 (range, 4.4-18.8) years were analyzed. The 896 bedside vital sign threshold alarms resulted in 160 alarm response opportunities (44 low RR, 74 high RR, and 42 low SpO2). In 141 periods (88% of total), for which video was available, 65% of alarms were deemed effective (followed by an alarm-related action within 10 minutes). Nurses were the sole responders in 55% of effective alarms and the patient or parent in 20%. Episodes of desaturation (SpO2 < 90%) were observed in 9 patients: At the time of the SpO2 paging trigger, the RR was >10 bpm in 6 of 9 patients. Based on all RR samples observed, the default alarm thresholds, to serve as a starting point for each patient, would be a low RR of 6 (>10 years of age) and 10 (4-9 years of age).

CONCLUSIONS

In this study, the use of RR monitoring did not improve the detection of respiratory depression. An RR threshold, which would have been predictive of desaturations, would have resulted in an unacceptably high false alarm rate. Future research using a combination of variables (e.g., SpO2 and RR), or the measurement of tidal volumes, may be needed to improve patient safety in the postoperative ward.

Remote monitoring of breathing dynamics using infrared thermography

An atypical or irregular respiratory frequency is considered to be one of the earliest markers of physiological distress. In addition, monitoring of this vital parameter plays a major role in diagnosis of respiratory disorders, as well as in early detection of sudden infant death syndrome. Nevertheless, the current measurement modalities require attachment of sensors to the patient's body, leading to discomfort and stress. The current paper presents a new robust algorithm to remotely monitor breathing rate (BR) by using thermal imaging. This approach permits to detect and to track the region of interest (nose) as well as to estimate BR. In order to study the performance of the algorithm, and its robustness against motion and breathing disorders, three different thermal recordings of 11 healthy volunteers were acquired (sequence 1: normal breathing; sequence 2: normal breathing plus arbitrary head movements; and sequence 3: sequence of specific breathing patterns). Thoracic effort (piezoplethysmography) served as "gold standard" for validation of our results. An excellent agreement between estimated BR and ground truth was achieved. Whereas the mean correlation for sequence 1-3 were 0.968, 0.940 and 0.974, the mean absolute BR errors reached 0.33, 0.55 and 0.96 bpm (breaths per minute), respectively. In brief, this work demonstrates that infrared thermography is a promising, clinically relevant alternative for the currently available measuring modalities due to its performance and diverse remarkable advantages.

A qualitative evaluation of capnography use in paediatric sedation: perceptions, practice and barriers

AIMS AND OBJECTIVES

We explored perceptions about capnography for procedural sedation and barriers to use in a paediatric emergency department.

BACKGROUND

Capnography is a sensitive monitor of ventilation and is increasingly being studied in procedural sedation. While benefits have been found, it has not gained wide acceptance for monitoring of children during sedation.

DESIGN

A qualitative exploratory study was performed.

METHODS

Using a grounded theory approach, physicians and nurses from the paediatric emergency department participated in one-on-one interviews about their experiences with and opinions of capnography. An iterative process of data collection and analysis was used to inductively generate theories and themes until theoretical saturation was achieved.

RESULTS

Five physicians and 12 nurses were interviewed. Themes included: Experiences: Participants felt that procedural sedation is safe and adverse events are rare. Normal capnography readings reassured providers about the adequacy of ventilation. Knowledge: Despite experience with capnography, knowledge and comfort varied. Most participants requested additional education and training. Diffusion of Use: While participants expressed positive opinions about capnography, use for sedation was infrequent. Many participants felt that capnography use increased in other paediatric populations, such as patients with altered mental status, ingestions or head trauma. Barriers: Identified barriers to use included a lack of comfort with or knowledge about equipment, lack of availability of the monitor and cannulas, lack of inclusion of these supplies on a checklist for procedural sedation preparedness, and lack of a policy for use of capnography during sedation.

CONCLUSION

Capnography use during sedation in the paediatric emergency department is limited despite positive experiences and opinions about this device. Addressing modifiable barriers such as instrument availability, continuing education, and inclusion on a checklist may increase use of capnography during sedation.

RELEVANCE TO CLINICAL PRACTICE

Despite the perceived benefits, a broad implementation plan is required to introduce capnography successfully to the paediatric emergency department.

Accuracy of CO₂ monitoring via nasal cannulas and oral bite blocks during sedation for esophagogastroduodenoscopy

Esophagogastroduodenoscopy procedures are typically performed under conscious sedation. Drug-induced respiratory depression is a major cause of serious adverse effects during sedation. Capnographic monitoring of respiratory activity improves patient safety during procedural sedation. This bench study compares the performance of the nasal cannulas and oral bite blocks used to monitor exhaled CO2 during sedation. We used a spontaneously breathing mechanical lung to evaluated four CO2 sampling nasal cannulas and three CO2 sampling bite blocks. We placed pneumatic resistors in the mouth of the manikin to simulate different levels of mouth opening. We compared CO2 measurements taken from the sampling device to CO2 measurements taken directly from the trachea. The end tidal CO2 concentration (PETCO2) measured through the bite blocks and nasal cannulas was always lower than the corresponding PETCO2 measured at the trachea. The difference became larger as the amount of oxygen delivered through the devices increased. The difference was larger during normal ventilation than during hypoventilation. The difference became larger as the amount of oral breathing increased. The two nasal cannulas without oral cups failed to provide sufficient CO2 for breath detection when the mouth was fully open and oxygen was delivered at 10 L/min. Our simulation found that respiratory rate can be accurately monitored during the procedure using a CO2 sampling bite block or a nasal cannula with oral cup. The accuracy of PETCO2 measurements depends on the device used, the amount of supplement oxygen, the amount of oral breathing and the patient's minute ventilation.

The effectiveness of oxygen delivery and reliability of carbon dioxide waveforms: a crossover comparison of 4 nasal cannulae

BACKGROUND

Effective O2 delivery and accurate end-tidal CO2 (ETCO2) sampling are essential features of nasal cannulae (NCs) in patients with compromised respiratory status. We studied 4 NC designs: bifurcated nasal prongs (NPs) with O2 delivery and CO2 sensing in both NPs (Hudson), separate O2/CO2 NPs (Salter), and CO2 sensing in NPs with cloud O2 delivery outside the NPs via multi vents (Oridion) and dual vents (Medline). We hypothesized that design differences between NCs would influence O2 delivery and ETCO2 detection.

METHODS

Forty-five healthy volunteers, 18 to 35 years, participated in an unrestricted, randomized block design, each subject serving as their own control in a 4-period crossover study design of 4 NCs during one session. Monitoring included electrocardiogram, posterior pharynx O2 sampling from a Hauge Airway (Sharn Anesthesia Products, Tampa, FL), and NC ETCO2. In 11 volunteers, radial artery blood was sampled from a catheter for partial pressures of O2 and carbon dioxide (PaO2 and PaCO2) determination. Per randomization, each NC was positioned, and data were collected over 2 minutes (ETCO2, pharyngeal O2, PaO2, and PaCO2) during room air and during O2 fresh gas flows (FGFs) of 2, 4, and 6 Lpm. Statistical analyses were performed with SAS Analytics Pro, Version 9.3, and JMP Statistical Software, Version 11 (SAS Institute Inc., Cary, NC), significance at P < 0.05.

RESULTS

Blood gas analyses indicated PaCO2 during steady state at each experimental time period remained unchanged from physiologic baseline. PaO2 did not differ between NC devices at baseline or 2 Lpm O2. The PaO2 at 4 Lpm from the separate NPs and bifurcated NCs was significantly higher than the multi-vented NC. Pharyngeal O2 with the NC with separate NPs was significantly higher than multivented and dual-vented cloud delivery NCs at 2, 4, and 6 Lpm FGF. Pharyngeal O2 with the NC with bifurcated NPs was significantly higher than the multi-vented NC at 2 Lpm, and higher than cloud delivery NCs at 4 and 6 Lpm FGF. ETCO2 was significantly lower with the NC with bifurcated NPs compared to the other 3 NCs, consistent with errant CO2 tracings at higher FGF.

CONCLUSIONS

NCs provide supplemental inspired O2 concentrations for patients with impaired pulmonary function. Accurate measures of ETCO2 are helpful in assessing respiratory rate and determining whether CO2 retention is occurring from hypoventilation. These findings suggest the NC with separate NPs was the most effective in delivering O2 and the most consistent at providing reliable CO2 waveforms at higher FGFs.

Sedation-related complications in gastrointestinal endoscopy

Defining the risk of procedural sedation for gastrointestinal endoscopic procedures remains a vexing challenge. The definitions as to what constitutes a cardiopulmonary unplanned event are beginning to take focus but the existing literature is an amalgam of various definitions and subjective outcomes, providing a challenge to patient, practitioner, and researcher. Gastrointestinal endoscopy when undertaken by trained personnel after the appropriate preprocedural evaluation and in the right setting is a safe experience. However, significant challenges exist in further quantifying the sedation risks to patients, optimizing physiologic monitoring, and sublimating the pharmacoeconomic and regulatory embroglios that limit the scope of practice and the quality of services delivered to patients.

A randomized controlled trial of capnography during sedation in a pediatric emergency setting

OBJECTIVE

Data suggest that capnography is a more sensitive measure of ventilation than standard modalities and detects respiratory depression before hypoxemia occurs. We sought to determine if adding capnography to standard monitoring during sedation of children increased the frequency of interventions for hypoventilation, and whether these interventions would decrease the frequency of oxygen desaturations.

METHODS

We enrolled 154 children receiving procedural sedation in a pediatric emergency department. All subjects received standard monitoring and capnography, but were randomized to whether staff could view the capnography monitor (intervention) or were blinded to it (controls). Primary outcome were the rate of interventions provided by staff for hypoventilation and the rate of oxygen desaturation less than 95%.

RESULTS

Seventy-seven children were randomized to each group. Forty-five percent had at least 1 episode of hypoventilation. The rate of hypoventilation per minute was significantly higher among controls (7.1% vs 1.0%, P = .008). There were significantly fewer interventions in the intervention group than in the control group (odds ratio, 0.25; 95% confidence interval [CI], 0.13-0.50). Interventions were more likely to occur contemporaneously with hypoventilation in the intervention group (2.26; 95% CI, 1.34-3.81). Interventions not in time with hypoventilation were associated with higher odds of oxygen desaturation less than 95% (odds ratio, 5.31; 95% CI, 2.76-10.22).

CONCLUSION

Hypoventilation is common during sedation of pediatric emergency department patients. This can be difficult to detect by current monitoring methods other than capnography. Providers with access to capnography provided fewer but more timely interventions for hypoventilation. This led to fewer episodes of hypoventilation and of oxygen desaturation.

The role of capnography in endoscopy patients undergoing nurse-administered propofol sedation: a randomized study

OBJECTIVE. Standard benzodiazepine/opioid cocktail has proven inferior to propofol sedation during complicated endoscopic procedures and in low-tolerance patients. Propofol is a short-acting hypnotic with a potential risk of respiratory depression at levels of moderate to deep sedation. The existing literature on capnography for endoscopy patients sedated with nurse-administered propofol sedation (NAPS) is limited. Can the addition of capnography to standard monitoring during endoscopy with NAPS reduce the number, duration, and level of hypoxia. MATERIALS AND METHODS. This study was a randomized controlled trial with an intervention group (capnography) and a control group (without capnography). Eligible subjects were consecutive patients for endoscopy at Gentofte Hospital compliant with the criteria of NAPS. RESULTS. Five hundred and forty patients, 263 with capnography and 277 without capnography, were included in the analysis. The number and total duration of hypoxia was reduced by 39.3% and 21.1% in the intervention group compared to the control group (p > 0.05). No differences in actions taken against insufficient respiration were found. Changes in end-tidal carbon dioxide (R = 0.177, p-value < 0.001) and respiratory rate (R = 0.092, p-value < 0.001) were correlated to oxygen saturation (SpO2) up to 36 s prior to changes in SpO2. CONCLUSIONS. Capnography seems to reduce the number and duration of hypoxia in NAPS patients (p > 0.05). Capnography is able to detect insufficient respiration that may lead to hypoxia prior to changes in pulse oximetry. However, due to a limited clinical benefit and additional costs associated with capnography, we do not find capnography necessary during the use of NAPS.

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.