The Effect of Physical Therapy on Regional Lung Function in Critically Ill Patients

Case report: Electrical impedance tomography-guided ventilator weaning in an obese patient with severe pneumonia

Background

Electrical impedance tomography (EIT) evaluates lung function by providing continuous, real-time monitoring of regional lung ventilation distribution to guide the restoration of lung ventilation. Patients with obesity who are dependent on mechanical ventilation often struggle with weaning. This case report highlights the potential of EIT to guide the weaning of ventilator-dependent patients in an obese patient with severe pneumonia.

Case summary

A 23-year-old male obese patient was admitted to Zhongshan People's Hospital in November 2023 due to progressive dyspnea. He suffered from recurrent fever and worsening oxygenation and had a 20+ year history of syringomyelia. Combined with abnormal computed tomography imaging, the discovery of a viral infection in the bronchoalveolar lavage fluid, and next-generation sequencing results, he was diagnosed with severe pneumonia. In addition to conventional treatment, EIT was used to guide him through postural changes and ventilation recovery. EIT-informed prone positioning improved ventilation distribution and facilitated successful ventilator weaning on day 26. The patient was discharged after recovering spontaneous respiratory function.

Conclusion

EIT may help ventilator-dependent obese patients achieve tailored targets to improve ventilatory outcomes.

Oxygen therapy and noninvasive respiratory supports in acute hypoxemic respiratory failure: a narrative review

BACKGROUND

This narrative review was written by an expert panel to the members of the jury to help in the development of clinical practice guidelines on oxygen therapy.

RESULTS

According to the expert panel, acute hypoxemic respiratory failure was defined as PaO2 < 60 mm Hg or SpO2 < 90% on room air, or PaO2/FiO2 ≤ 300 mm Hg. Supplemental oxygen should be administered according to the monitoring of SpO2, with the aim at maintaining SpO2 above 92% and below 98%. Noninvasive respiratory supports are generally reserved for the most hypoxemic patients with the aim of relieving dyspnea. High-flow nasal cannula oxygen (HFNC) seems superior to conventional oxygen therapy (COT) as a means of avoiding intubation and may therefore be should probably be used as a first-line noninvasive respiratory support in patients requiring more than 6 L/min of oxygen or PaO2/FiO2 ≤ 200 mm Hg and a respiratory rate above 25 breaths/minute or clinical signs of respiratory distress, but with no benefits on mortality. Continuous positive airway pressure (CPAP) cannot currently be recommended as a first-line noninvasive respiratory support, since its beneficial effects on intubation remain uncertain. Despite older studies favoring noninvasive ventilation (NIV) over COT, recent clinical trials fail to show beneficial effects with NIV compared to HFNC. Therefore, there is no evidence to support the use of NIV or CPAP as first-line treatment if HFNC is available. Clinical trials do not support the hypothesis that noninvasive respiratory supports may lead to late intubation. The potential benefits of awake prone positioning on the risk of intubation in patients with COVID-19 cannot be extrapolated to patients with another etiology.

CONCLUSIONS

Whereas oxygen supplementation should be initiated for patients with acute hypoxemic respiratory failure defined as PaO2 below 60 mm Hg or SpO2 < 90% on room air, HFNC should be the first-line noninvasive respiratory support in patients with PaO2/FiO2 ≤ 200 mm Hg with increased respiratory rate. Further studies are needed to assess the potential benefits of CPAP, NIV through a helmet and awake prone position in patients with acute hypoxemic respiratory failure not related to COVID-19.

Oxygen therapy in acute hypoxemic respiratory failure: guidelines from the SRLF-SFMU consensus conference

INTRODUCTION

Although largely used, the place of oxygen therapy and its devices in patients with acute hypoxemic respiratory failure (ARF) deserves to be clarified. The French Intensive Care Society (Société de Réanimation de Langue Française, SRLF) and the French Emergency Medicine Society (Société Française de Médecine d'Urgence, SFMU) organized a consensus conference on oxygen therapy in ARF (excluding acute cardiogenic pulmonary oedema and hypercapnic exacerbation of chronic obstructive diseases) in December 2023.

METHODS

A committee without any conflict of interest (CoI) with the subject defined 7 generic questions and drew up a list of sub questions according to the population, intervention, comparison and outcomes (PICO) model. An independent work group reviewed the literature using predefined keywords. The quality of the data was assessed using the GRADE methodology. Fifteen experts in the field from both societies proposed their own answers in a public session and answered questions from the jury (a panel of 16 critical-care and emergency medicine physicians, nurses and physiotherapists without any CoI) and the public. The jury then met alone for 48 h to write its recommendations.

RESULTS

The jury provided 22 statements answering 11 questions: in patients with ARF (1) What are the criteria for initiating oxygen therapy? (2) What are the targets of oxygen saturation? (3) What is the role of blood gas analysis? (4) When should an arterial catheter be inserted? (5) Should standard oxygen therapy, high-flow nasal cannula oxygen therapy (HFNC) or continuous positive airway pressure (CPAP) be preferred? (6) What are the indications for non-invasive ventilation (NIV)? (7) What are the indications for invasive mechanical ventilation? (8) Should awake prone position be used? (9) What is the role of physiotherapy? (10) Which criteria necessarily lead to ICU admission? (11) Which oxygenation device should be preferred for patients for whom a do-not-intubate decision has been made?

CONCLUSION

These recommendations should optimize the use of oxygen during ARF.

Progress in electrical impedance tomography and bioimpedance

Scope. This focus collection aims at presenting recent advances in electrical impedance tomography (EIT), including algorithms, hardware, and clinical applications.Editorial. This focus collection of articles published by the journalPhysiological Measurementintroduces the Progress in EIT and Bioimpedance. It follows conferences in South Korea and Germany, that provided a platform for new research ideas.

The influence of gravity on electrical impedance tomography measurements during upper body position change

Objective

The aim of the study was to examine the influence of gravity on regional ventilation measured by electrical impedance tomography (EIT) with the standard electrode belt position at the 5th intercostal space during tilting from supine to sitting positions.

Methods

A total of 30 healthy volunteers were examined prospectively in supine position during quiet tidal breathing. Subsequently, the bed was tilted so that the upper body of the subjects achieved 30, 60 and 90° every 3 min. Regional ventilation distribution and end-expiratory lung impedance (EELI) were monitored with EIT throughout the whole experiment. Absolute tidal volumes were measured with spirometry and the volume-impedance ratio was calculated for each position.

Results

The volume-impedance ratio did not differ statistically between the studied body positions but 11 subjects exhibited a large change in ratio at one of the positions (outside 99.3% coverage). In general, ventilation distribution became more heterogeneous and moved towards dorsal regions as the upper body was tilted to 90-degree position. EELI increased and tidal volume decreased. The lung regions identified at various positions differed significantly.

Conclusion

Gravity has non-negligible influence on EIT data, as the upper body tilted from supine to sitting positions. The standard electrode belt position might be reconsidered if ventilation distribution is to be compared between supine and sitting positions.

Systemic and Cerebral Effects of Physiotherapy in Mechanically Ventilated Subjects

BACKGROUND

Physiotherapy may result in better functional outcomes, shorter duration of delirium, and more ventilator-free days. The effects of physiotherapy on different subpopulations of mechanically ventilated patients on respiratory and cerebral function are still unclear. We evaluated the effect of physiotherapy on systemic gas exchange and hemodynamics as well as on cerebral oxygenation and hemodynamics in mechanically ventilated subjects with and without COVID-19 pneumonia.

METHODS

This was an observational study in critically ill subjects with and without COVID-19 who underwent protocolized physiotherapy (including respiratory and rehabilitation physiotherapy) and neuromonitoring of cerebral oxygenation and hemodynamics. PaO2 /FIO2 , PaCO2 , hemodynamics (mean arterial pressure [MAP], mm Hg; heart rate, beats/min), and cerebral physiologic parameters (noninvasive intracranial pressure, cerebral perfusion pressure using transcranial Doppler, and cerebral oxygenation using near-infrared spectroscopy) were assessed before (T0) and immediately after physiotherapy (T1).

RESULTS

Thirty-one subjects were included (16 with COVID-19 and 15 without COVID-19). Physiotherapy improved PaO2 /FIO2 in the overall population (T1 = 185 [108-259] mm Hg vs T0 = 160 [97-231] mm Hg, P = .02) and in the subjects with COVID-19 (T1 = 119 [89-161] mm Hg vs T0 = 110 [81-154] mm Hg, P = .02) and decreased the PaCO2 in the COVID-19 group only (T1 = 40 [38-44] mm Hg vs T0 = 43 [38-47] mm Hg, P = .03). Physiotherapy did not affect cerebral hemodynamics, whereas increased the arterial oxygen part of hemoglobin both in the overall population (T1 = 3.1% [-1.3 to 4.9] vs T0 = 1.1% [-1.8 to 2.6], P = .007) and in the non-COVID-19 group (T1 = 3.7% [0.5-6.3] vs T0 = 0% [-2.2 to 2.8], P = .02). Heart rate was higher after physiotherapy in the overall population (T1 = 87 [75-96] beats/min vs T0 = 78 [72-92] beats/min, P = .044) and in the COVID-19 group (T1 = 87 [81-98] beats/min vs T0 = 77 [72-91] beats/min, P = .01), whereas MAP increased in the COVID-19 group only (T1 = 87 [82-83] vs T0 = 83 [76-89], P = .030).

CONCLUSIONS

Protocolized physiotherapy improved gas exchange in subjects with COVID-19, whereas it improved cerebral oxygenation in non-COVID-19 subjects.

An Update on Cardiorespiratory Physiotherapy during Mechanical Ventilation

Physiotherapists are integral members of the multidisciplinary team managing critically ill adult patients. However, the scope and role of physiotherapists vary widely internationally, with physiotherapists in some countries moving away from providing early and proactive respiratory care in the intensive care unit (ICU) and focusing more on early mobilization and rehabilitation. This article provides an update of cardiorespiratory physiotherapy for patients receiving mechanical ventilation in ICU. Common and some more novel assessment tools and treatment options are described, along with the mechanisms of action of the treatment options and the evidence and physiology underpinning them. The aim is not only to summarize the current state of cardiorespiratory physiotherapy but also to provide information that will also hopefully help support clinicians to deliver personalized and optimal patient care, based on the patient's unique needs and guided by accurate interpretation of assessment findings and the current evidence. Cardiorespiratory physiotherapy plays an essential role in optimizing secretion clearance, gas exchange, lung recruitment, and aiding with weaning from mechanical ventilation in ICU. The physiotherapists' skill set and scope is likely to be further optimized and utilized in the future as the evidence base continues to grow and they get more and more integrated into the ICU multidisciplinary team, leading to improved short- and long-term patient outcomes.