POCUS in Critical Care Physiotherapy: Give Me Sight Beyond Sight

An overview of the main ultrasonographic tools that allow physiotherapists to improve their evaluation in the critical patient, described through the mnemonic PHISIO.

Introduction

Ultrasound is considered to be the fifth pillar of the physical examination to provide and improve patient care (Narula et al. 2018). In critically ill patients, the limited time to make differential diagnoses and decisions in treatment are crucial for patient survival. Point of Care of Ultrasound (POCUS) can help with these needs in the intensive care unit (ICU) by reaching an accurate diagnosis and providing adequate management, resulting in a valuable diagnostic tool (Díaz-Gómez et al. 2021; Lau and See 2022). Furthermore, POCUS applications have been gaining strength and evidence in respiratory care and physical rehabilitation. The use of this tool seems to be setting itself as a powerful ally for physical therapists treating critically ill patients.

The main ultrasonographic evaluations that will allow physiotherapists to improve their evaluation and attention in the critical patient are described below through the mnemonic “PHISIO” (Figures 1-2).

P = Pulmonary

Pulmonary ultrasound is currently feasible for the diagnosis of respiratory failure through the BLUE (Bedside Lung Ultrasound in Emergency) protocol (Leidi et al. 2020; Lichtenstein et al. 2004). However, it is useful for the physiotherapist to identify different types of ultrasound profiles to guide chest physiotherapy and in-depth respiratory monitoring (Lichtenstein et al. 2004; Le Neindre et al. 2016). According to the ultrasound profile presented by the patient, the physiotherapist can guide and apply different care strategies or treatments. For example, in the case of B-lines, non-invasive mechanical ventilation (NIV), PEP devices and active early mobilisation including verticalisation through sitting and standing can be applied. The goal would be to improve aeration and pulmonary ventilation through devices, positioning or exercise (Le Neindre et al. 2016; Hickmann et al. 2021). It is important to mention that in the case of pulmonary coalescence and subpleural consolidations, precautions should be taken into account by the rehabilitation staff. Early mobilisation (EM) or rehabilitation protocols in the ICU need to ensure the cause of respiratory failure has been stabilised to be safe. Pulmonary oedema or an infectious process can be monitored with ultrasound allowing us to observe changes over time and deciding the correct timing in the initiation of an early mobilisation programme (Le Neindre et al. 2016).

A common finding in critically ill patients can be the presence of pulmonary consolidations and will suggest pneumonia (dynamic air bronchogram) accompanied by clinical criteria, or atelectasis (static air bronchogram) (Lichtenstein et al. 2009; Sartori and Tombesi 2010). In the case of pneumonia, the effect of the antibiotic must be assessed and airway clearance techniques may be considered. On the other hand, when facing atelectasis, bronchial hygiene techniques such as those that favour peak expiratory flow (Marti et al. 2013; Amaral et al. 2020), manual or mechanical hyperinflation (Paulus et al. 2012; Assmann et al. 2016; Tucci et al. 2019), PEP devices, positioning in different decubitus, cough assistance and verticalisation (Le Neindre et al. 2016; Westerdahl et al. 2005; Volpe et al. 2018; Gates et al. 2021) can be some tools that may help the resolution of such problems. Also, pleural effusions, empyema and haemothorax can be identified faster through ultrasound compared to x-ray (Soni et al. 2015; Walsh et al. 2021). This allows early interventions such as pleural drainage accompanied by breathing exercises with PEP devices (Dos Santos et al. 2020) that improve ventilation and lung function, as well as prevent diaphragmatic dyskinesia (Le Neindre et al. 2016; Leech et al. 2015; Valenza-Demet et al. 2014). NIV should be applied with caution as it may limit lymphatic drainage and consequently pleural drainage. The use of conventional oxygen therapy devices or high-flow oxygenation therapy combined with active exercise and inspiratory muscle training (IMT) is preferable for pleural drainage due to the negative pressure generated (Walden et al. 2013).

Finally, the overall Lung Ultrasound Score (LUS) of >17 points allows us to determine the failure in the Spontaneous Breathing Trial (SBT) during the weaning process. Similarly, >6 B lines in anterolateral fields, may indicate weaning-induced pulmonary oedema (WIPO) (Santangelo et al. 2022). It is important to consider previous pulmonary pathologies and the evaluation of echocardiography for this matter.