Go with the flow-clinical importance of flow curves during mechanical ventilation: A narrative review

Stepwise Ventilator Waveform Assessment to Diagnose Pulmonary Pathophysiology

Clinicians can use mechanical waveform analysis as a diagnostic tool to identify pulmonary pathophysiology. This review offers an approach to develop a hypothesis of a patient’s lung pathophysiology.

Static and Dynamic Measurements of Compliance and Driving Pressure: A Pilot Study

Rationale

Monitoring tidal cycle mechanics is key to lung protection. For this purpose, compliance and driving pressure of the respiratory system are often measured clinically using the plateau pressure, obtained after imposing an extended end-inspiratory pause, which allows for relaxation of the respiratory system and redistribution of inflation volume (method A). Alternative methods for estimating compliance and driving pressure utilize the measured pressure at the earliest instance of zero flow (method B), the inspiratory slope of the pressure-time tracing during inflation with constant flow (method C), and the expiratory time constant (method D).

Methods

Ten passive mechanically ventilated subjects, at a large tertiary referral center, underwent measurements of compliance and driving pressure using the four different methods. The inspiratory tidal volume, inspiratory to expiratory ratio, and positive end expiratory pressures were then adjusted from baseline and the measurements re-obtained.

Results

Method A yielded consistently higher compliance and lower driving pressure calculations compared to methods B and C. Methods B and C most closely approximated one another. Method D did not yield a consistent reliable pattern.

Conclusion

Static measurements of compliance and driving pressure using the plateau pressure may underestimate the maximum pressure experienced by the most vulnerable lung units during dynamic inflation. Utilizing the pressure at zero flow as a static measurement, or the inspiratory slope as a dynamic measurement, may calculate a truer estimate of the maximum alveolar pressure that generates stress upon compromised lung units.

Acupuncture for COVID-19 patient after ventilator weaning: A protocol for systematic review and meta-analysis

BACKGROUND

COVID-19 has spread globally since its outbreak in late 2019. It mainly attacks people's respiratory system. Many patients with severe COVID-19 require a ventilator to support breathing, and their lung function is often impaired to varying degrees after ventilator weaning. Acupuncture has been reported to improve respiratory function, but there is no evidence that it can improve respiratory function in ventilator users with COVID-19 after they are removed from the machine. The protocol of the systematic review and meta-analysis will clarify safety and effectiveness of acupuncture on respiratory rehabilitation after weaning from the ventilator during the treatment of COVID-19.

METHODS

We will search PubMed, EMBASE, MEDLINE, the Cochrane Library, Chinese National Knowledge Infrastructure, Chinese Biomedical Literature Database, Chinese Science and Technology Periodical Database, Wanfang Database, Clinical Trials and Chinese Clinical Trial Registry. Relevant English language and Chinese language literature will be included. A combination of subject words and free text words will be applied in the searches. The complete process will include study selection, data extraction, risk of bias assessment, and meta-analyses. We will use subgroup analysis and sensitivity analysis to explore the sources of heterogeneity if there is heterogeneity. We will use funnel charts to assess the risk of bias. Endnote X9.3 will be used to manage data screening. The statistical analysis will be completed by RevMan5.2 or Stata/SE 15.1 software.

RESULTS

This study will assess safety and effectiveness of acupuncture for rehabilitation on respiratory function after weaning from the ventilator during the treatment of COVID-19.

CONCLUSIONS

The conclusion of this study will give evidence to prove safety and effectiveness of acupuncture for rehabilitation on respiratory after weaning from the ventilator during the treatment of COVID-19.

REGISTRATION

PROSPERO CRD42020206889.