The Role of Pocus in Acute Respiratory Failure: A Narrative Review on Airway and Breathing Assessment

Abstract

Acute respiratory failure (ARF) is a challenging condition that clinicians, especially in emergency settings, have to face frequently. Especially in emergency settings, many underlying diseases can lead to ARF and life-threatening conditions have to be promptly assessed and correctly treated to avoid unfavorable outcomes. In recent years, point-of-care ultrasound (POCUS) gained growing consideration due to its bedside utilization, reliability and reproducibility even in emergency settings especially in unstable patients. Research on POCUS application to assess ARF has been largely reported mainly with observational studies showing heterogeneous results from many different applications. This narrative review describes the wide potentiality of POCUS to face airways and breathing life-threatening conditions such as upper airway management, pulmonary and pleural pathologies and diaphragm impairment. We conducted extensive research of the literature to report from major studies to case reports deemed useful in practical clinical utilization of POCUS in ARF. Due to the huge amount of the literature found, we focused on airways and breathing assessment trying to systematize the evidence according to clinical care of ARF in emergency settings. Further studies, possibly trials, should determine how POCUS is crucial in clinical practice in terms of standard of care improvements, patient safety and cost-benefit analysis.

Keywords: COPD; acute heart failure; acute respiratory failure; diaphragm impairment; heart failure; lung effusion; lung ultrasound; pneumonia; pneumothorax; upper airways management.

Figure 1

Transverse view of normal vocal folds during valsalva (adduction). FVF, false vocal fold; TVF, true vocal fold. White arrow indicates hyperechoic medial margins of true vocal folds meeting in midline. Reproduced with permission of Dr. Noel from [20].

Figure 2

Transverse view of normal vocal folds during relaxation (abduction). ARY, arytenoid; FVF, false vocal fold; TVF, true vocal fold. White arrows indicate hyperechoic medial margins of true vocal folds. Reproduced with permission of Dr. Noel from [20].

Figure 3

The imaging from laryngeal ultrasound demonstrates the air column width before (A) and after (B) endotracheal tube cuff deflation. After cuff deflation, the fan-shaped widening air column width obliterates surrounding structures such as vocal cords and arytenoid cartilage by acoustic shadow (T, thyroid cartilage; V, vocal cord; A, arytenoid cartilage). Reproduced with permission of Dr. Sutherasan from [16].

Figure 4

The Blue Protocol ([80], modified).

Figure 5

Example of LUS images of (A) normal aerated lung with pleural and A-line; (B) pleural effusion and associated parenchymal consolidation; (C) B-lines sign of interstitial syndrome.

Figure 6

(A,B): Measurement of the end-inspiratory and end-expiratory diaphragmatic thickness; (C) measurement of the DE.