Diagnostic value of volumetric capnography in patients with chronic cough variant asthma

Flow-Field Inference for Turbulent Exhale Flow Measurement

BACKGROUND

Vision-based pulmonary diagnostics present a unique approach for tracking and measuring natural breathing behaviors through remote imaging. While many existing methods correlate chest and diaphragm movements to respiratory behavior, we look at how the direct visualization of thermal CO2 exhale flow patterns can be tracked to directly measure expiratory flow.

METHODS

In this work, we present a novel method for isolating and extracting turbulent exhale flow signals from thermal image sequences through flow-field prediction and optical flow measurement. The objective of this work is to introduce a respiratory diagnostic tool that can be used to capture and quantify natural breathing, to identify and measure respiratory metrics such as breathing rate, flow, and volume. One of the primary contributions of this work is a method for capturing and measuring natural exhale behaviors that describe individualized pulmonary traits. By monitoring subtle individualized respiratory traits, we can perform secondary analysis to identify unique personalized signatures and abnormalities to gain insight into pulmonary function. In our study, we perform data acquisition within a clinical setting to train an inference model (FieldNet) that predicts flow-fields to quantify observed exhale behaviors over time.

RESULTS

Expiratory flow measurements capturing individualized flow signatures from our initial cohort demonstrate how the proposed flow field model can be used to isolate and analyze turbulent exhale behaviors and measure anomalous behavior.

CONCLUSIONS

Our results illustrate that detailed spatial flow analysis can contribute to unique signatures for identifying patient specific natural breathing behaviors and abnormality detection. This provides the first-step towards a non-contact respiratory technology that directly captures effort-independent behaviors based on the direct measurement of imaged CO2 exhaled airflow patterns.

Monitoring the Resolution of Acute Exacerbation of Airway Bronchoconstriction in an Asthma Attack Using Capnogram Waveforms

Patients with acute bronchospasm can show a distinct slope of the capnogram ("shark fin") as a result of asynchronous alveolar excretion. Although the slope of the upward alveolar plateau (phase III) in the capnogram waveforms of non-intubated patients is known to help monitor the therapeutic response to acute bronchospasm, little is known about the significance of its slope among intubated patients. Therefore, we quantified the phase III slope of an intubated patient with acute asthma to investigate whether capnogram waveforms could be useful for identifying the response to antibronchospasm treatment in real time.

CASE SUMMARY

The patient was a 53-year-old man who had a history of asthma. He presented to the emergency department with the primary complaint of respiratory distress. He was diagnosed with severe asthma attack and required invasive mechanical ventilation for 10 days, during which we quantified the phase III slope of the capnogram. The phase III slope decreased during treatment, with a significant reduction from the third to the fourth day; however, a significant decrease in end-tidal carbon dioxide (EtCO₂) was observed from the fifth to the sixth day. We found that the slope values decreased earlier than EtCO₂ reduction, although the absolute EtCO₂ values eventually decreased in response to antibronchospasm treatment.

CONCLUSION

There were several reports that evaluated the phase III slope in non-intubated patients with asthma, but this is the first report measuring the phase III slope in an intubated patient over several days. Capnogram waveforms may serve as useful real-time indicators to monitor acute bronchospasm among mechanically ventilated patients.

Consensus on intratympanic drug delivery for Menière's disease

Purpose

Intratympanic (IT) drug delivery receives attention due to its effectivity in treatment for Menière’s disease (MD). Due to the release of the consensuses and new evidence on IT drug delivery for MD have been published, the review with a view to supplementing the details of IT treatment of MD is indispensable.

Methods

The literatures on IT injection for MD treatment over the last two decades are retrieved, International consensus (ICON) on treatment of Menière’s disease (2018), Clinical Practice Guideline (2020) and European Position statement on Diagnosis and Treatment of Meniere’s Disease (2018) are taken into account for reference, and follow advice from experts from Europe, USA and China.

Results

Experts agree on the following: (1) The effectiveness of IT methylprednisolone (ITM) on vertigo control seems to be somewhat better than that of IT dexamethasone (ITD), and ITM can restore hearing in some cases. (2) Due to the ototoxicity of aminoglycosides, the application of intratympanic gentamicin (ITG) in MD patients with good hearing is conservative. However, some studies suggest that ITG with low doses has no significant effect on hearing, which needs to be further proved by clinical studies with high levels of evidence. (3) Currently, generally accepted treatment endpoint of ITG is no vertigo attack in a 12-month period or a vestibular loss in objective tests in the affected ear.

Conclusion

More studies with high level of evidence are needed to evaluate the drug type, efficacy, and therapeutic endpoint of IT therapy for MD.