Influence of donor capnometry on renal graft evolution in uncontrolled donation after circulatory death

AIM

To analyse the association between donor capnometry data and the short-term evolution of kidney grafts in cases of uncontrolled donation after circulatory death (uDCD).

METHOD

We used an ambispective observational study design, conducted in the Community of Madrid between January and December 2019, inclusive. Patients who suffered out-of-hospital cardiac arrest (CA) with no response to advanced cardiopulmonary resuscitation (CPR) were selected as potential donors. Donor capnometry levels were measured at the start, midpoint and transfer to hospital then compared with indicators of renal graft evolution.

RESULTS

The initial selection included 34 possible donors, of which 12 (35.2%) were viable donors from whom 22 (32.3%)kidneys were recovered. There was a correlation between the highest capnometry values and less need for post-transplant dialysis (≥24 mmHg, p< 0.017), fewer dialysis sessions and fewer days to recover correct renal function (Rho -0.47, p< 0.044). There was a significant inverse correlation between the capnometry values at transfer and 1-month post-transplant creatinine levels (Rho -0.62, p< 0.033). There were no significant differences between the capnometry values at transfer and primary nonfunction (PNF) or warm ischaemia time. One-year patient survival was 100% for patient receiving organ donation, while graft survival was 95%.

CONCLUSIONS

Capnometry levels at transfer are a useful predictor of the short-term function and viability of kidney transplants from uncontrolled donations after circulatory death.

Arterial to end-tidal CO2 gradients during isocapnic hyperventilation

Isocapnic hyperventilation (ICHV) is occasionally used to maintain the end-expired CO₂ partial pressure (P_ETCO₂) when the inspired CO₂ (P_ICO₂) rises. Whether maintaining P_ETCO₂ with ICHV during an increase of the P_ICO₂ also maintains arterial PCO₂ (P_aCO₂) remains poorly documented. 12 ASA PS I-II subjects undergoing a robot-assisted radical prostatectomy (RARP) (n = 11) or cystectomy (n = 1) under general endotracheal anesthesia with sevoflurane in O₂/air (40% inspired O₂) were enrolled. P_ICO₂ was sequentially increased from 0 to 0.5, 1.0, 1.5 and 2% by adding CO₂ to the inspiratory limb of the circle system, while increasing ventilation to a target P_ETCO₂ of 4.7-4.9% by adjusting respiratory rate during controlled mechanical ventilation. P_a-ETCO₂ gradients were determined after a 15 min equilibration period at each P_ICO₂ level and compared using ANOVA. Mean (standard deviation) age, height, and weight were 66 (6) years, 171 (6) cm, and 75 (8) kg, respectively. Capnograms were normal and hemodynamic parameters remained stable. P_ETCO₂ could be maintained within 4.7-4.9% in all subjects at all times except in 1 subject with 1.5% P_ICO₂ and 5 subjects with 2.0% P_ICO₂; data from the one subject in whom both 1.5 and 2.0% P_ICO₂ resulted in P_ETCO₂ > 5.1% were excluded from analysis. P_a-ETCO₂ gradients did not change when P_ICO₂ increased. The effect of a modest rise of P_ICO₂ up to 1.5% on P_ETCO₂ during RARP can be readily overcome by increasing ventilation without altering the P_a-ETCO₂ gradients. At higher P_ICO₂, airway pressures may become a limiting factor, which requires further study.

Feasibility of portable capnometer for mechanically ventilated preterm infants in the delivery room

This study aimed to determine whether a specific portable capnometer (EMMA™) can facilitate the maintenance of an appropriate partial pressure of arterial carbon dioxide (PaCO₂) in intubated preterm infants in the delivery room. This study included preterm infants with a gestational age of 26 + 0 to 31 + 6 weeks who required intubation in the delivery room. We prospectively identified 40 infants who underwent the EMMA™ monitoring intervention group and 43 infants who did not undergo monitoring (historical control group). PaCO₂ was evaluated either at admission in the neonatal intensive care unit or at 2 h after birth. The proportion of infants with an appropriate PaCO₂ (35-60 mmHg) was greater in the intervention group than in the control group (80% vs. 42%; p = 0.001). There were no significant differences in the rate of accidental extubation (5.0% vs. 7.0%, p = 1.00) or in the proportion of infants with an appropriate PaCO₂ among infants whose birth weight was < 1000 g (54% vs. 40%, p = 0.49). However, among infants whose birth weight was ≥ 1000 g, the PaCO₂ tended to be more appropriate in the intervention group than in the control group (93% vs. 44%; p < 0.001).Conclusion: The EMMA™ facilitated the maintenance of an appropriate PaCO₂ for mechanically ventilated preterm infants, especially infants with birth weight ≥1000 g, in the delivery room. What is Known: • An inappropriate partial pressure of arterial carbon dioxide has been associated with intraventricular hemorrhage in preterm infants. • There is a need to appropriately control the partial pressure of arterial carbon dioxide in preterm infants. What is New: • This is the first report regarding the feasibility of a portable capnometer, the EMMA™, in the delivery room. • The EMMA™ may be considered a feasible monitoring device in the delivery room for intubated preterm infants, especially infants with birth weight ≥1000 g.

Guidelines on analgosedation, monitoring, and recovery time for flexible bronchoscopy: a systematic review

BACKGROUND

Patients undergoing bronchoscopy in spontaneous breathing are prone to hypoxaemia and hypercapnia. Sedation, airway obstruction, and lung diseases impair respiration and gas exchange. The restitution of normal respiration takes place in the recovery room. Nonetheless, there is no evidence on the necessary observation time. We systematically reviewed current guidelines on bronchoscopy regarding sedation, monitoring and recovery.

METHODS

This review was registered at the PROSPERO database (CRD42020197476). MEDLINE and awmf.org were double-searched for official guidelines, recommendation or consensus statements on bronchoscopy from 2010 to 2020. The PICO-process focussed on adults (Patients), bronchoscopy with maintained spontaneous breathing (Interventions), and recommendations regarding the intra- and postprocedural monitoring and sedation (O). The guideline quality was graded. A catalogue of 54 questions was answered. Strength of recommendation and evidence levels were recorded for each recommendation.

RESULTS

Six guidelines on general bronchoscopy and three expert statements on special bronchoscopic procedures were identified. Four guidelines were evidence-based. Most guidelines recommend sedation to improve the patient's tolerance. Midazolam combined with an opioid is preferred. The standard monitoring consists of non-invasive blood pressure, and pulse oximetry, furthermore electrocardiogram in cardiac patients. Only one guideline discusses hypercapnia and capnometry, but without consensus. Two guidelines discuss a recovery time of two hours, but a recommendation was not given because of lack of evidence.

CONCLUSION

Evidence for most issues is low to moderate. Lung-diseased patients are not represented by current guidelines. Capnometry and recovery time lack evidence. More primary research in these fields is needed so that future guidelines may address these issues, too.

Chest compressions induce errors in end-tidal carbon dioxide measurement

BACKGROUND

Real-time measurement of end-tidal carbon dioxide (ETCO₂) is used as a non-invasive estimate of cardiac output and perfusion during cardiopulmonary resuscitation (CPR). However, capnograms are often distorted by chest compressions (CCs) and this may affect ETCO₂ measurement. The aim of the study was to quantify the effect of CC-artefact on the accuracy of ETCO₂ measurements obtained during out-of-hospital manual CPR.

METHODS

We retrospectively analysed monitor-defibrillator recordings collected by two advanced life support agencies during out-of-hospital cardiac arrest. These two agencies, represented as A and B used different side-stream capnometers and monitor-defibrillators. One-minute capnogram segments were reviewed. Each ventilation within each segment was identified using the transthoracic impedance signal and the capnogram. ETCO₂ values per ventilation were manually annotated and compared to the corresponding capnometry values stored in the monitor-defibrillator. Ventilations were classified as distorted or non-distorted by CC-artefact.

RESULTS

A total of 407 1-min capnogram segments from 65 patients were analysed. Overall, 4095 ventilations were annotated, 2170 (32.4% distorted) and 1925 (31.8% distorted) for agency A and B, respectively. Median (IQR) unsigned error in ETCO₂ measurement increased from 1.5 (0.6-3.1)% for non-distorted to 5.5 (1.8-14.1)% for distorted ventilations; from 0.7 (0.3-1.2)% to 3.7 (1.0-9.9)% in agency A and from 2.3 (1.2-3.9)% to 8.3 (3.9-19.5)% in agency B (p < 0.001). Errors were higher than 10 mmHg in 9% and higher than 15 mmHg in 5% of the distorted ventilations.

CONCLUSION

CC-artefact causes ETCO₂ measurement errors in the two studied devices. This suggests that capnometer algorithms may need to be adapted to reliably perform in the presence of CC-artefact during CPR.

Sleep-disordered breathing and effects of non-invasive ventilation on objective sleep and nocturnal respiration in patients with myotonic dystrophy type I

Patients with myotonic dystrophy type I (DM1) may develop nocturnal hypoventilation, requiring non-invasive ventilation. Data on long-term adherence to non-invasive ventilation, or sleep and ventilation outcomes are scarce. We retrospectively collected baseline polysomnography and capnometry results from 36 adult patients with sleep-related symptoms (42.9 ± 12.5 years, 20 female), plus follow-up sleep study records from those treated with non-invasive ventilation. Sleep-disordered breathing was found in 33 patients (91.7%) including 8 (22.2%) with daytime hypercapnia. Twenty-six patients (72.2%) showed nocturnal hypoventilation on transcutaneous capnometry. The sensitivity of oximetry to detect nocturnal hypoventilation was only 0.38. Twenty-eight patients (77.8%) showed sleep apnea, which was predominantly obstructive (n = 8), central (n = 9), or "mixed" (n = 11). Thirty-two patients were initiated on non-invasive ventilation which significantly improved ventilation and oxygenation in the first night of treatment. Follow-up revealed stable normoxia and normocapnia without deterioration of sleep outcomes for up to 52 months. Adherence to treatment was low to moderate, with substantial inter-individual variability. Sleep disordered breathing is highly prevalent in adult DM1 patients complaining of daytime sleepiness, and non-invasive ventilation significantly, rapidly and persistently improves nocturnal gas exchange. Capnometry is superior to oximetry for detection of nocturnal hypoventilation. Adherence to non-invasive ventilation remains a major issue in DM1, and long-term treatment benefits should be individually assessed.

Human and equipment resources for difficult airway management, airway education programs, and capnometry use in Japanese emergency departments: a nationwide cross-sectional study

BACKGROUND

Although human and equipment resources, proper training, and the verification of endotracheal intubation are vital elements of difficult airway management (DAM), their availability in Japanese emergency departments (EDs) has not been determined. How ED type and patient volume affect DAM preparation is also unclear. We conducted the present survey to address this knowledge gaps.

METHODS

This nationwide cross-sectional study was conducted from April to September 2016. All EDs received a mailed questionnaire regarding their DAM resources, airway training methods, and capnometry use for tube placement. Outcome measures were the availability of: (1) 24-h in-house back-up; (2) key DAM resources, including a supraglottic airway device (SGA), a dedicated DAM cart, surgical airway devices, and neuromuscular blocking agents; (3) anesthesiology rotation as part of an airway training program; and (4) the routine use of capnometry to verify tube placement. EDs were classified as academic, tertiary, high-volume (upper quartile of annual ambulance visits), and urban.

RESULTS

Of the 530 EDs, 324 (61.1%) returned completed questionnaires. The availability of in-house back-up coverage, surgical airway devices, and neuromuscular blocking agents was 69.4, 95.7, and 68.5%, respectively. SGAs and dedicated DAM carts were present in 51.5 and 49.7% of the EDs. The rates of routine capnometry use (47.8%) and the availability of an anesthesiology rotation (38.6%) were low. The availability of 24-h back-up coverage was significantly higher in academic EDs and tertiary EDs in both the crude and adjusted analysis. Similarly, neuromuscular blocking agents were more likely to be present in academic EDs, high-volume EDs, and tertiary EDs; and the rate of routine use of capnometry was significantly higher in tertiary EDs in both the crude and adjusted analysis.

CONCLUSIONS

In Japanese EDs, the rates of both the availability of SGAs and DAM carts and the use of routine capnometry to confirm tube placement were approximately 50%. These data demonstrate the lack of standard operating procedures for rescue ventilation and post-intubation care. Academic, tertiary, and high-volume EDs were likely to be well prepared for DAM.

Is increased positive end-expiratory pressure the culprit? Autoresuscitation in a 44-year-old man after prolonged cardiopulmonary resuscitation: a case report

BACKGROUND

The phenomenon of autoresuscitation is rare, yet it is known to most emergency physicians. However, the pathophysiology of the delayed return of spontaneous circulation remains enigmatic. Among other causes hyperinflation of the lungs and excessively high positive end-expiratory pressure have been suggested, but reports including cardiopulmonary monitoring during cardiopulmonary resuscitation are scarce to support this hypothesis.

CASE PRESENTATION

We report a case of autoresuscitation in a 44-year-old white man after 80 minutes of advanced cardiac life support accompanied by continuous capnometry and repeated evaluation by ultrasound and echocardiography. After prolonged cardiopulmonary resuscitation, refractory electromechanical dissociation on electrocardiogram and ventricular akinesis were recorded. In addition, a precipitous drop in end-tidal partial pressure of carbon dioxide was noted and cardiopulmonary resuscitation was discontinued. Five minutes after withdrawal of all supportive measures his breathing resumed and a perfusing rhythm ensued.

CONCLUSIONS

Understanding the underlying pathophysiology of autoresuscitation is hampered by a lack of reports including extensive cardiopulmonary monitoring during cardiopulmonary resuscitation in a preclinical setting. In this case, continuous capnometry was combined with repetitive ultrasound evaluation, which ruled out most assumed causes of autoresuscitation. Our observation of a rapid decline in end-tidal partial pressure of carbon dioxide supports the hypothesis of increased intrathoracic pressure. Continuous capnometry can be performed easily during cardiopulmonary resuscitation, also in a preclinical setting. Knowledge of the pathophysiologic mechanisms may lead to facile interventions to be incorporated into cardiopulmonary resuscitation algorithms. A drop in end-tidal partial pressure of carbon dioxide, for example, might prompt disconnection of the ventilation to allow left ventricular filling. Further reports and research on this topic are encouraged.

Difficult airway management resources and capnography use in Japanese intensive care units: a nationwide cross-sectional study

Purpose

The availability of difficult airway management (DAM) resources and the extent of capnometry use in Japanese intensive care units (ICUs) remained unclear. The purpose of this study was to clarify whether: (1) DAM resources were adequate, and (2) capnometry was routinely applied in Japanese ICUs.

Methods

This nationwide cross-sectional study was conducted from September 2015 to February 2016. All ICUs received a mailed questionnaire about their DAM resources and use of capnometry. Outcome measures were availability of: (1) 24-h in-house backup coverage; (2) a supraglottic airway device (SGA); (3) a dedicated DAM cart; and (4) surgical airway devices, and (5) routine use of capnometry to verify tube placement and for continuous monitoring of ventilator-dependent patients. The association between these outcomes and ICU type (academic, high-volume, closed, surgical) was also analyzed.

Results

Of the 289 ICUs, 196 (67.8 %) returned completed questionnaires. In-house backup coverage and surgical airway devices were highly available (89.3 and 95.9 %), but SGAs and dedicated DAM carts were not (60.2 and 60.7 %). The routine use of capnometry to confirm tube placement was reported by 55.6 % of the ICUs and was highest in closed ICUs (67.2 %, p = 0.03). The rate of continuous capnography monitoring was also 55.6 % and was highest in academic ICUs (64.5 %, p = 0.04).

Conclusion

In Japanese ICUs, SGAs and dedicated DAM carts were less available, and capnometry was not universally applied either to confirm tube placement, or for continuous monitoring of ventilated patients. Our study revealed areas in need of improvement.

Electronic supplementary material

The online version of this article (doi:10.1007/s00540-016-2176-3) contains supplementary material, which is available to authorized users.

Transcutaneous PTCCO2 measurement in combination with arterial blood gas analysis provides superior accuracy and reliability in ICU patients

Hyper or hypoventilation may have serious clinical consequences in critically ill patients and should be generally avoided, especially in neurosurgical patients. Therefore, monitoring of carbon dioxide partial pressure by intermittent arterial blood gas analysis (PaCO₂) has become standard in intensive care units (ICUs). However, several additional methods are available to determine PCO₂ including end-tidal (PETCO₂) and transcutaneous (PTCCO₂) measurements. The aim of this study was to compare the accuracy and reliability of different methods to determine PCO₂ in mechanically ventilated patients on ICU. After approval of the local ethics committee PCO₂ was determined in n = 32 ICU consecutive patients requiring mechanical ventilation: (1) arterial PaCO₂ blood gas analysis with Radiometer ABL 625 (ABL; gold standard), (2) arterial PaCO₂ analysis with Immediate Response Mobile Analyzer (IRMA), (3) end-tidal PETCO₂ by a Propaq 106 EL monitor and (4) transcutaneous PTCCO₂ determination by a Tina TCM4. Bland-Altman method was used for statistical analysis; p < 0.05 was considered statistically significant. Statistical analysis revealed good correlation between PaCO₂ by IRMA and ABL (R² = 0.766; p < 0.01) as well as between PTCCO₂ and ABL (R² = 0.619; p < 0.01), whereas correlation between PETCO₂ and ABL was weaker (R² = 0.405; p < 0.01). Bland-Altman analysis revealed a bias and precision of 2.0 ± 3.7 mmHg for the IRMA, 2.2 ± 5.7 mmHg for transcutaneous, and -5.5 ± 5.6 mmHg for end-tidal measurement. Arterial CO₂ partial pressure by IRMA (PaCO₂) and PTCCO₂ provided greater accuracy compared to the reference measurement (ABL) than the end-tidal CO₂ measurements in critically ill in mechanically ventilated patients patients.

Comparison of end-tidal CO2 measured by transportable capnometer (EMMA™ capnograph) and arterial pCO2 in general anesthesia

An end-tidal CO2 monitor (capnometer) is used most often as a noninvasive substitute for PaCO2 in anesthesia, anesthetic recovery, and intensive care. Additionally, the wide spread on-site use of portable capnometers in emergency and trauma situations is now observed. This study was conducted to compare PaCO2 measurement between the EMMA™ portable-capnometer and sidestream capnometry. End-tidal CO2 (portable capnometer: EMMA™ capnograph, side stream capnometry module: Datex-Ohmeda S5 Anesthesia Monitor) levels were recorded at the time of arterial blood gas sampling of patients undergoing general anesthesia. Data were compared using the Bland and Altman method, and by evaluating the clinical significance performed by calculating the percent error (%). A total of 100 data were obtained from 35 patients. The bias of PaCO2 and portable capnometer was 6.0 mmHg, where the upper and lower limits of the agreement were 11.8 and 0.3 mmHg, respectively. The percent error was 18.0 %. The bias of side stream capnometry and portable capnometer was 2.2 mmHg, where the upper and the lower limits of the agreement were 6.0 and -1.6 mmHg, respectively. The percent error was 13.0 %. Significant differences between the PETCO2 and PaCO2 values of the EMMA™ portable-capnometer were not observed for patients undergoing general anesthesia. ClinicalTrials.gov identifier NCT02184728.

A Review of Carbon Dioxide Monitoring During Adult Cardiopulmonary Resuscitation

Although high quality cardiopulmonary resuscitation is one of the most significant factors related to favourable outcome, its quality depends on many components, such as airway management, compression depth and chest recoil, hands-off time, and early defibrillation. The most common way of controlling the resuscitation efforts is monitoring of end-tidal carbon dioxide. The International Liaison Committee on Resuscitation suggests this method both for in-hospital and out-of-hospital cardiac arrest. However, despite the abundant human and animal studies supporting the usefulness of end-tidal carbon dioxide, its optimal values during cardiopulmonary resuscitation remain controversial. In this review, the advantages and effectiveness of end-tidal carbon dioxide during cardiopulmonary resuscitation are discussed and specific target values are suggested based on the available literature.

Pulmonary function responses to ozone in smokers with a limited smoking history

In non-smokers, ozone (O3) inhalation causes decreases in forced expiratory volume (FEV1) and dead space (VD) and increases the slope of the alveolar plateau (SN). We previously described a population of smokers with a limited smoking history that had enhanced responsiveness to brief O3 boluses and aimed to determine if responsiveness to continuous exposure was also enhanced. Thirty smokers (19M, 11F, 24±4 years, 6±4 total years smoking,4±2 packs/week) and 30 non-smokers (17M, 13F, 25±6 years) exercised for 1h on a cycle ergometer while breathing 0.30ppm O3. Smokers and non-smokers were equally responsive in terms of FEV1 (-9.5±1.8% vs -8.7±1.9%). Smokers alone were responsive in terms of VD (-6.1±1.2%) and SN (9.1±3.4%). There was no difference in total delivered dose. Dead space ventilation (VD/VT) was not initially different between the two groups, but increased in the non-smokers (16.4±2.8%) during the exposure, suggesting that the inhaled dose may be distributed more peripherally in smokers. We also conclude that these cigarette smokers retain their airway responsiveness to O3 and, uniquely, experience changes in VD that lead to heterogeneity in airway morphometry and an increase in SN.

The use of capnometry to predict arterial partial pressure of CO(2) in non-intubated breathless patients in the emergency department

Background

Capnometry measures carbon dioxide in expired air and provides the clinician with a noninvasive measure of the systemic metabolism, circulation and ventilation. This study was carried out on patients with acute breathlessness to define the utility and role of capnometry in the emergency department.

Aim

The objectives of the study were:

To determine the correlation between end tidal CO₂ and PaCO₂ in non-intubated acutely breathless patients.

To determine factors that influence the end tidal carbon dioxide (ETCO₂).

To determine the correlation between ETCO₂ with PaCO₂ in patients presenting with pulmonary disorders.

Methods

One hundred fifty acutely breathless patients arriving at the emergency department and fulfilling the inclusion and exclusion criteria were chosen during a 6-month study period. The patients gave written or verbal consent, and were triaged and treated according to their presenting complaints. Demographic data were collected, and the ETCO₂ data were recorded. Arterial blood gas was taken in all patients. The data were compiled and analyzed using various descriptive studies from the Statistics Program for Social Studies (SPSS) version 12. Correlation between ETCO₂ and PaCO₂ was analyzed using the Pearson correlation coefficient. Other variables also were analyzed to determine the correlation using simple linear regression. The agreement and difference between ETCO₂ and PaCO₂ were analyzed using paired sample t-tests.

Results

There is a strong correlation between ETCO₂ and PaCO₂ using the Pearson correlation coefficient: 0.716 and p value of 0.00 (p < 0.05). However, the paired t-test showed a mean difference between the two parameters of 4.303 with a p value < 0.05 (95% CI 2.818, 5.878). There was also a good correlation between ETCO₂ and acidosis state with a Pearson correlation coefficient of 0.374 and p value 0.02 (p < 0.05). A strong correlation was also observed between ETCO₂ and a hypocapnic state, with a Pearson correlation coefficient of 0.738 (p < 0.05). Weak correlation was observed between alkalosis and ETCO₂, with a Pearson correlation coefficient of 0.171 (p < 0.05). A strong negative correlation was present between ETCO₂ and hypercapnic patients presenting with pulmonary disorders, with a Pearson correlation coefficient of -0.738 (p < 0.05) and of -0.336 (p < 0.05), respectively.

Conclusion

This study shows that ETCO₂ can be used to predict the PaCO₂ level when the difference between the PaCO₂ and ETCO₂ is between 2 to 6 mmHg, especially in cases of pure acidosis and hypocapnia. Using ETCO₂ to predict PaCO₂ should be done with caution, especially in cases that involve pulmonary disorders and acid-base imbalance.