Measurement of combined oximetry and cutaneous capnography during flexible bronchoscopy

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.

Improved diagnostic yield of transbronchial lung biopsy in peripheral pulmonary lesions using a combination of endobronchial ultrasound and rapid on-site evaluation

OBJECTIVES

To evaluate the value of rapid on-site evaluation (ROSE) during radial probe endobronchial ultrasound transbronchial lung biopsy (rpEBUS-TBLB) for peripheral pulmonary lesions (PPLs).

METHODS

One hundred and six patients with PPLs who received rpEBUS-TBLB were enrolled in this study. One specimen was immediately examined by ROSE and the other was sent to the central laboratory for cytologic diagnosis. The results of ROSE were compared with those of pathological diagnosis.

RESULTS

The diagnostic accuracy, sensitivity, and specificity of ROSE during rpEBUS-TBLB for PPLs were 82.1%, 89.6%, and 77.1%, respectively. The procedure times and number of biopsies were less for procedures when ROSE was positive compared with those when ROSE was negative (procedure time: 20.5 ± 7.9 vs. 28.3 ± 7.6 minutes; number of biopsies: 1.6 ± 0.9 vs. 2.8 ± 0.6 times). No serious procedural complications were observed.

CONCLUSIONS

ROSE has value for diagnosing PPLs during rpEBUS. It can reduce procedure time, number of biopsies, and complications. ROSE combined with rpEBUS is an effective and safe method for the diagnosis of PPLs.

Hypercapnia in COPD Patients Undergoing Endobronchial Ultrasound under Local Anaesthesia and Analgosedation: A Prospective Controlled Study Using Continuous Transcutaneous Capnometry

BACKGROUND

Flexible bronchoscopy (FB) in analgosedation causes alveolar hypoventilation and hypercapnia, the more so if patients suffer from COPD. Nonetheless, neither is capnometry part of standard monitoring nor is there evidence on how long patients should be monitored after sedation.

OBJECTIVES

We investigated the impact of COPD on hypercapnia during FB with endobronchial ultrasound (EBUS) in sedation and how the periprocedural monitoring should be adapted.

METHODS

Two cohorts of consecutive patients - with advanced and without COPD - with the indication for FB with EBUS-guided transbronchial needle aspiration in analgosedation received continuous transcutaneous capnometry (ptcCO2) before, during, and for 60 min after the sedation with midazolam and alfentanil.

MAIN RESULTS

Forty-six patients with advanced COPD and 44 without COPD were included. The mean examination time was 26 ± 9 min. Patients with advanced COPD had a higher peak ptcCO2 (53.7 ± 7.1 vs. 46.8 ± 4.8 mm Hg, p < 0.001) and mean ptcCO2 (49.5 ± 6.8 vs. 44.0 ± 4.4 mm Hg, p < 0.001). Thirty-six percent of all patients reached the maximum hypercapnia after FB in the recovery room (8 ± 11 min). Patients with COPD needed more time to recover to normocapnia (22 ± 24 vs. 7 ± 11 min, p < 0.001). They needed a nasopharyngeal tube more often (28 vs. 11%, p < 0.001). All patients recovered from hypercapnia within 60 min after FB. No intermittent ventilation manoeuvres were needed.

CONCLUSION

A relevant proportion of patients reached their peak-pCO2 after the end of intervention. We recommend using capnometry at least for patients with known COPD. Flexible EBUS in analgosedation can be safely performed in patients with advanced COPD. For patients with advanced COPD, a postprocedural observation time of 60 min was sufficient.

Interventional Pulmonology

Bronchoscopy presents a unique challenge and need for collaboration between anesthesia providers and bronchoscopists. The approach to topical anesthesia, analgesia, and sedation must be customized based on complexity, duration, and setting. The bronchoscopy team must work together in each phase of the procedure to ensure patient safety and allow completion of a quality bronchoscopy. Airway access may change depending on the type of procedure planned and must be discussed before each case. Intraprocedural difficulties with ventilation, airway pressure, and sedation may arise that must be addressed together. This review highlights an approach to these common challenges.

Evaluation of a flexible bronchoscope prototype designed for bronchoscopy during mechanical ventilation: a proof-of-concept study

Bronchoscopy during mechanical ventilation of patients' lungs significantly affects ventilation because of partial obstruction of the tracheal tube, and may thus be omitted in the most severely ill patients. It has not previously been possible to reduce the external diameter of the bronchoscope without reducing the diameter of the suction channel, thus reducing the suctioning capacity of the device. We believed that a better-designed bronchoscope could improve the safety of bronchoscopy in patients whose lungs were ventilated. We designed a flexible bronchoscope prototype with a drumstick-shaped head consisting of a long, thin proximal portion; a short and large distal portion for camera docking; and a large suction channel throughout the length of the device. The aims of our study were to test the impact of our prototype on mechanical ventilation when inserted into the tracheal tube, and to assess suctioning capacity. We first tested the efficiency of the suction channel, and demonstrated that the suction flow of the prototype was similar to that of conventional adult bronchoscopes. We next evaluated the consequences of bronchoscopy when using the prototype on minute ventilation and intrathoracic pressures during mechanical ventilation: firstly, in vitro using a breathing simulator; and secondly, in vivo using a porcine model of pulmonary ventilation. The insertion of adult bronchoscopes into the tracheal tube immediately impaired the protective ventilation strategy employed, whereas the prototype preserved it. For the first time, we have developed an innovative flexible bronchoscope designed for bronchoscopy during invasive mechanical ventilation, that both preserved the protective ventilation strategy, and enabled efficient suction flow.

Short term general anesthesia for retro-bulbar block in ophthalmic surgery generates no significant hypercapnia

To assess the impact of short time hypnosis for retro-bulbar anesthesia on ventilation in patients undergoing ophthalmic surgery of the anterior eye chamber. In all patients, a combined continuous transcutaneous carbon dioxide tension (PtcCO₂) and partial oxygen saturation (SpO₂) measurement was applied in addition to routine monitoring. To enable unconscious application of retro-bulbar anesthesia, intravenous thiopental was given in one to multiple bolus doses. Transient breathing support included chin lift, Esmarch maneuver and manual hand-bag ventilation via face mask. Main endpoints were apnea time, recovery time according to the Richmond Agitation Sedation Scale, as well as SpO₂ and PtcCO₂ readings at predefined time points. Fifty-two patients with a mean age of 68 ± 13 years were included. Average thiopental dose was 2.7 ± 0.6 mg/kg. In seven (13.5%) patients repeated doses of thiopental were necessary to a total of 3.3 ± 1.1 mg/kg. Except one patient, no severe, significant or clinical relevant hypercapnia or desaturation periods were observed, and the occurring elevation of PtcCO₂ values did not correlate with the application of repeated doses of thiopental or the need for the Esmarch maneuver. Higher PtcCO₂ values were associated with the presence of hypertension and smoking. Apnea (p < 0.001) and recovery (p = 0.003) time were significantly prolonged in the patients needing the Esmarch maneuver. Short term anesthesia with thiopental in ophthalmic surgery is associated with a mild but not clinically relevant hypercapnia.

End-tidal capnographic monitoring to detect apnea episodes during flexible bronchoscopy under sedation

Background

Apnea developing as a result of oversedation is a potential clinical problem in patients undergoing flexible bronchoscopy (FB) under sedation. However, there are no reports of evaluation using a standardized method of the frequency of occurrence of apnea episodes during FB under sedation. The aim of this study was to investigate the frequency of apnea episodes during FB under sedation in the clinical setting by end-tidal capnography.

Methods

This study was a single-institution retrospective review of a prospectively maintained database and medical records, including capnographic data, from April 2015 to March 2016. We enrolled patients who were sedated with midazolam and underwent diagnostic FB under end-tidal capnographic monitoring. Apnea was defined as cessation of airflow for more than 10 s.

Results

Data from a total of 121 eligible patients were analyzed. A total of 131 apnea episodes (median duration 33 s) were recorded in 59 patients (48.8%). Prolonged apnea episodes lasting for more than 30 s occurred in 24 patients (19.8%). Furthermore, 55 apnea episodes (42.0%) were followed by a decline of the SpO₂ by ≥4% from the baseline.

Conclusions

In this study, end-tidal capnography revealed the occurrence of apnea episodes at a high frequency in patients undergoing FB under sedation in the clinical setting.

Alveolar ventilation in children during flexible bronchoscopy

BACKGROUND

Hypoxia and hypercarbia complicate flexible bronchoscopy (FB). Unlike oxygenation by pulse-oximetry, alveolar ventilation is not routinely monitored during FB. The aim of this study was to investigate ventilation in children undergoing FB by measuring carbon-dioxide (CO₂ ) levels using the transcutaneous technique.

METHODS

Children admitted for FB were recruited. In addition to routine monitoring, transcutaneous CO₂ (TcCO₂ ) levels were recorded. All were sedated using the same protocol.

RESULTS

Ninety-five children were studied. There was no association between peak TcCO₂ or rise in TcCO₂ and age, weight percentile, bronchoscope size, or diagnosis. Median baseline TcCO₂ was 36 mmHg (IQR 32,40), median peak TcCO₂ was 51 mmHg (IQR 43,62) with median TcCO₂ rise of 17 mmHg (IQR 6.5,23.7). A rise of 15 mmHg or higher was recorded in 55% (n = 52) patients. Children requiring total propofol dose over 3.5 mg/kg had a significantly higher TcCO₂ peak of 57.6 mmHg (IQR 47.8,66.7) compared to 47.1 mmHg (IQR 40,57) (P = 0.004) and a higher rise in TcCO₂ 22.5 mmHg (IQR 17,33.9) compared to 13.6 mmHg (6,22) (P = 0.001). Results were not affected by intranasal midazolam and broncho-alveolar lavage. No complications were reported. Non clinically significant (i.e., not lower than 90%) brief drops in oxygen saturation were observed.

CONCLUSIONS

A large proportion of children undergoing FB have significant alveolar hypoventilation indicated by a rise in TcCO₂ . Monitoring ventilation with TcCO₂ is feasible and should be added during FB particularly in cases that are expected to require large amounts of sedation and patients susceptible to complications from respiratory acidosis. Pediatr Pulmonol. 2016;51:1177-1182. © 2016 Wiley Periodicals, Inc.

Diagnostic utility and accuracy of rapid on-site evaluation of bronchoscopic brushings

The aim of the study was to determine the accuracy of rapid on-site examinations, performed on transbronchial brushings of peripheral pulmonary lesions, in determining final bronchoscopic diagnosis. In addition to determining if rapid on-site examination impacts procedural outcomes. A prospective cohort study of consecutive patients with peripheral pulmonary lesions, which had been located by radial endobronchial ultrasound, was undertaken. Bronchoscopy was terminated if rapid on-site examination demonstrated diagnostic malignant material. Non-diagnostic rapid on-site examination resulted in further bronchoscopic sampling, including transbronchial lung biopsy and/or sampling from different locations. 128 peripheral pulmonary lesions were located by endobronchial ultrasound in 118 patients. The final bronchoscopic diagnoses included nonsmall cell lung cancer (n=76), carcinoid (n=3), and metastatic malignancy (n=3). Procedure times were significantly shorter for procedures when rapid on-site examinations demonstrated malignancy compared to those where rapid on-site examination was non-diagnostic (19±8 min versus 31±11 min, respectively; p<0.0001). In four procedures, initial negative rapid on-site examination results prompted redirection of sampling from alternate bronchial segments, resulting in positive diagnostic tissue being obtained. Positive and negative predictive value of rapid on-site examination for a malignant bronchoscopic diagnosis was 63 (97%) out of 65, and 43 (68%) out of 63, respectively. Rapid on-site examination of brushing specimens has a very high, positive, predictive value for bronchoscopic diagnosis of cancer and shortens the bronchoscopy procedure times. It has the potential to reduce complications, improve cost-effectiveness, and may improve diagnostic performance via live feedback.

Flexible bronchoscopy may decrease respiratory muscle strength: premedicational midazolam in focus

BACKGROUND

Flexible bronchoscopy (FB) is a procedure accepted to be safe in general, with low complication rates reported. On the other hand, it is known that patients with pre-existing respiratory failure have developed hypoventilation following FB. In this study the effects of FB on respiratory muscle strength were investigated by measuring maximum respiratory pressures.

METHODS

One hundred and forty patients, aged between 25 and 90 years, who had undergone diagnostic bronchoscopy between February 2012 and May 2012, were recruited to the study. Pre- and post-procedure maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured. A correlation between the MIP and MEP changes and patient characteristics and FB variables were investigated.

RESULTS

Significant decreases in both MIP and MEP values were observed following FB (p < 0.001 for both). Decreases were attributed to the midazolam used for sedation. Significant decreases in respiratory muscle strengths were observed especially in the high-dose midazolam group, compared to both low-dose and non-midazolam groups.

CONCLUSIONS

It was determined that respiratory muscle weakness may arise post-procedure in patients who have undergone FB, and this is constitutively related to midazolam premedication. Respiratory muscle weakness might play a role in potential hypoventilation in critical patients who undergo FB.

Significant hypercapnia either in CO(2)-insufflated or air-insufflated colonoscopy under deep sedation

BACKGROUND

previous reports showed that CO(2)-insufflated colonoscopy is safe and less discomfortable. However, hypercapnia remains a vital concernment if deep sedation is necessary for difficult colonoscopy with prolonged CO(2) insufflation. This observational study is to measure bodily CO(2) subjected to colonoscopy facilitated by CO(2)- and air- or air-insufflation in conscious-sedation, deep-sedation and awake patients.

OBJECTIVE

to investigate if CO(2)-insufflated colonoscopy could increase the risk of hypercapnia in awake, conscious-sedation and deep-sedation patients.

METHODS

104 patients in our health center undergoing sequential esophagogastroscopy and colonoscopy screening were included. At patients' request, incremental intravenous sedatives were given in order that the air-insufflated esophagogastroscopy could be carried out without the molestation of gag and cough reflexes. The sedation levels were re-evaluated before proceeding colonoscopy and the patients were divided into conscious-sedation (respond purposefully to verbal commands) and deep-sedation groups and randomly allocated for air or CO(2) insufflation. Transcutaneous capnography (TcCO(2)) was recorded every minute throughout the colonoscopy procedure.

RESULTS

the baseline TcCO(2) in the air- (50.9 ± 5.7 mmHg) and CO(2)-insufflated (53.1 ± 6.5 mmHg) groups under deep sedation was significantly higher than the groups under conscious-sedation and the awake groups (p < 0.01). In both air- and CO(2)-insufflation groups there were also a statistically significant (p < 0.01) correlation in TcCO(2) between the start, the peak and the end of colonoscopy. TcCO(2) did not significantly change throughout the colonoscopy in awake and conscious-sedation groups, either with air or CO(2) insufflation. With deep sedation, TcCO(2) significantly increased and peaked around the time when the scope touching the cecum, and then returned to original state with suction and withdrawl of the colonoscope without significant interaction of CO(2) insufflation and deep sedation.

CONCLUSION

the TcCO(2) during colonoscopy was correlated to the data before inserting colonoscope but significantly different within awake, conscious-sedation and deep-sedation groups. TcCO(2) did not change significantly either with CO(2) insufflation or air insufflations in awake and conscious-sedation groups. However, in deep-sedation groups with significantly higher baseline TcCO(2), further increase of TcCO(2) were significant without interaction with CO(2) insufflation. We concluded that when patients need deep sedation for colonoscopic procedures facilitated by gas insufflation, hypercapnia is still considerably present, not only with CO(2) insufflation but also with air insufflation colonoscopy.

Transcutaneous carbon dioxide in severe COPD patients during bronchoscopic lung volume reduction

BACKGROUND

Patients undergoing bronchoscopy are usually monitored only by pulse oximetry, hence hypoventilation cannot be assessed. Transcutaneous carbon dioxide tension (TcPCO(2)) monitoring is a non-invasive technique to assess hypoventilation. Patients with severe chronic obstructive pulmonary disease (COPD) undergoing bronchoscopy are at increased risk for sedation-induced hypoventilation. The aim of the study was to measure TcPCO(2) using a digital sensor to examine the occurrence of hypoventilation during bronchoscopic lung volume reduction (BLVR).

METHODS

Combined TcPCO(2) and SpO(2) saturation and arterial blood gases (ABG) were prospectively measured in 15 patients with severe COPD (Mean FEV(1) 29%) undergoing BLVR under conscious sedation with IV midazolam and IV alfentanil.

RESULTS

A highly significant correlation was noted between simultaneous ABG PCO(2) samplings and TcPCO(2) measured (R = 0.85, p < 0.001). Mean baseline TcPCO(2) level was 41.7 ± 10.3 mm Hg (±SD) (range 35-66 mmHg)], and peak measurement during the procedure was 61 ± 17.1 mm Hg (range 41-111 mmHg). The mean increase in TcPCO(2) during bronchoscopy was 19.2 (range 3.7-45 mmHg) [p < 0.0001]. Mean duration of significant hypercapnea (TcPCO(2) > 55 mmHg), observed in 7 (46%) patients, was 9 min (range 0-53).

CONCLUSIONS

Bronchoscopy performed under conscious sedation in patients with severe COPD is frequently associated with significant hypoventilation that can only be detected by TcPCO(2) monitoring. Combined measurement of SpO(2) and TcPCO(2) during bronchoscopy enhances patient safety, helps guide administration of sedation, and can alert physicians to the need for anesthesia reversal following completion of bronchoscopic interventions.

Comparison of combined oximetry and cutaneous capnography using a digital sensor with arterial blood gas analysis

BACKGROUND

Cutaneous carbon dioxide tension (PcCO(2)) is a promising non-invasive surrogate measure of arterial partial pressure of carbon dioxide (PaCO(2)).

OBJECTIVES

To compare values of PcCO(2) and oxygen saturation (SpO(2)) with arterial blood gas (ABG) analysis.

METHODS

SpO(2) and PcCO(2) were measured with a v-Sign-sensor (Sentec AG, Therwil, Switzerland) and the values compared with simultaneously obtained SaO(2) and PaCO(2) obtained from ABG analysis (ABL 725, Radiometer, Copenhagen, Denmark) in 275 adult patients referred to the lung function laboratory.

RESULTS

Median of the PcCO(2) was 4.7 kPa (interquartile range [IQR] 0.9 kPa). Median of the SpO(2) was 97% (IQR 3%). Bland-Altman analysis for comparison of PcCO(2) with PaCO(2) showed a bias of -0.1 kPa with a precision of +/- 0.9 kPa with 3.7% outlying values. Bland-Altman analysis for the comparison of SpO(2) and SaO(2) showed a bias of 20.1 % with a precision of +/- 3.5%. There were no complications.

CONCLUSION

There is a good agreement between combined cutaneous capnography and oximetry values with ABG analysis. Due to the excellent safety profile and the short time to get a continuous measurement, this technique should be examined in settings where it can complement repeated ABG analysis when ventilatory disturbances are suspected or non-invasive monitoring of ventilation is needed.

[Validation of the transcutaneous carbon dioxide tension measurements in critical paediatric patients]

OBJECTIVE

To estimate the accuracy of the transcutaneous carbon dioxide tension measurement (PtCO(2)) compared to the measurement of the arterial carbon dioxide tension (PaCO(2)).

MATERIAL AND METHODS

An analytical, longitudinal, prospective and observational study, of a dynamic cohort taken from the in-patients of a Paediatric Intensive Care Unit (PICU). The PtCO(2) was measured with the SenTec AG analyzer, and the sensor was applied with the specific Multi-Site Attachment Ring. PtCO(2) and PaCO(2) were recorded at the same time. The statistical significance of the association between paired measurements was evaluated with the Snedecor's F test, the Pearson's r(2) correlation coefficient and the Interclass Correlation Coefficient (ICC). The degree of agreement was evaluated with the Bland & Altman method. The consistency of the results was evaluated with the ANalysis Of the VAriance (ANOVA).

RESULTS

One hundred and six paired measurements, PtCO(2) and PaCO(2), from twelve patients, were compared. The means of the PaCO(2) and PtCO(2) were 51.0+/-13mmHg and 50.1+/-14mmHg, respectively; r(2)=0.87 (p<0.001), ICC=0.96, (95% CI: 0.94-0.97). The Bland-Altman analysis showed a mean difference of-0.9mmHg (95% CI:-2.0 to 0.2mmHg). The correlation was better in cases with no respiratory disease, with low respiratory assistance, with PaCO(2)>50mmHg and with the sensor applied on the forehead. The results were consistent. No side effects derived from the use of the ring were observed.

CONCLUSION

The correlation between PtCO(2) and PaCO(2) is excellent and stable. The ring sensor was safe and easy to use.

Transcutaneous PCO2 monitors are more accurate than end-tidal PCO2 monitors

PURPOSE

The accuracy of monitors for measuring transcutaneous PCO2 (TcPCO2), end-tidal PCO2 (EtPCO2), and nasal EtPCO2 was evaluated.

METHODS

The measuring devices included a TcPCO2 monitor (TCM3; Radiometer Trading), an EtPCO2 monitor (Ultima; Datex-Ohmeda), and a nasal EtPCO2 monitor (TG-920P; Nihon Kohden). The sensor electrode of the TCM3 TcPCO2 monitor was applied to the skin of the subject's upper arm. A sampling tube attached to the proximal end of the tracheal tube was connected to the Ultima EtPCO2 monitor. The miniature sensor of the TG-920P nasal EtPCO2 monitor was attached to the nostril. The values obtained were compared with direct measurements of arterial PCO2 (PaCO2) obtained by means of an ABL700 blood gas analyzer (Radiometer Trading) in surgically treated patients. The means +/- 2 SD of the differences between variables were calculated.

RESULTS

The TcPCO2 monitor (0.19 +/- 4.8 mmHg, mean +/- 2-SD) was more accurate than the EtPCO2 monitor (-4.4 +/- 6.5 mmHg, mean +/- 2-SD) in patients receiving artificial ventilation via an endotracheal tube and the TcPCO2 monitor was also more accurate than the nasal EtPCO2 monitor (-6.3 +/- 9.8 mmHg, bias +/- 2-SD) in patients breathing spontaneously.

CONCLUSION

We found that the TcPCO2 monitor was more accurate than the EtPCO2 or nasal EtPCO2 monitor in surgically treated patients.