key: cord-0975151-66fomer6
authors: Helmy, Mina Adlof; Hasanin, Ahmed; Milad, Lydia Magdy; Mostafa, Maha; Fathy, Shaimaa
title: Parasternal intercostal muscle thickening as a predictor of non-invasive ventilation failure in patients with COVID-19
date: 2022-04-26
journal: Anaesth Crit Care Pain Med
DOI: 10.1016/j.accpm.2022.101063
sha: 6cbd6d6d9074f5dbfa62384384a3b9797f4486d9
doc_id: 975151
cord_uid: 66fomer6

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Therefore, it is essential to have accurate and simple tools for monitoring patient's response to NIV and facilitating the decision and timing of invasive mechanical ventilation. Assessment of diaphragmatic function provides an excellent tool for predicting the outcomes of patients with COVID-19 on admission and during weaning [3, 4] . Increased activity of the intercostal muscles was observed in patients with respiratory failure and correlated with the degree of diaphragmatic dysfunction in non-COVID-19 patients [5] . This study aimed to evaluate the ability of parasternal intercostal muscle thickening fraction (PIC-TF) to predict NIV failure in patients with .

This prospective observational study was conducted in a tertiary hospital after obtaining approval from the institutional ethics committee (N-131-2021). Before enrolment, written informed consents were obtained from the patient's next of kin.

We included patients with severe COVID-19, according to the World Health Organization criteria, who were receiving NIV after the failure of simple oxygen therapy (failure to maintain peripheral oxygen saturation [SpO2] ≥ 92% and/or respiratory rate > 30). According to the local protocols, NIV was considered a failure, and invasive mechanical ventilation was initiated if SpO2 was < 90%, respiratory rate > 35 breaths/min, respiratory acidosis, haemodynamic instability, or altered consciousness level. All patients received non-invasive mechanical ventilation, and none received high-flow nasal oxygen. The patients were managed according to local protocols and the Surviving Sepsis Campaign guidelines. All intensivists who managed the patients had no role in the data collection or radiological examination. Figure 1A) . The cyclic respiratory changes in muscle thickening were measured using the M-mode, and PIC-TF (the percentage change in intercostal muscle thickness at peak inspiration in relation to intercostal muscle thickness at end expiration) was calculated using the following formula: {(Inspiratory muscle thickness -expiratory muscle thickness) /expiratory muscle thickness × 100} ( Figure 1B) .

Diaphragmatic excursion (DE) was evaluated using a low-frequency curved probe (4C-RS, 2-5 MHz) placed at one of the lower intercostal spaces in the right anterior and left midaxillary lines. Computed tomography (CT) score was evaluated by a radiologist who was blinded to clinical data [3, 4] .

The primary outcome of this study was the accuracy of PIC-TF in predicting a composite outcome of NIV failure or in-hospital mortality. Other outcomes included the accuracy of room air SpO2, respiratory rate, DE, and CT score in predicting the primary outcome. The patients' vital signs, laboratory and radiological markers at admission, and outcomes were recorded.

If the incidence of NIV failure and/or in-hospital mortality in patients with severe COVID-19 is 35%, a minimum of 28 patients were needed to detect an area under the Table) .

The AUCs (95% confidence interval) for right and left PIC-TF for predicting NIV failure and/or in-hospital mortality were 0.83 (0.64-0.95) and 0.84 (0.65-0.95) with positive predictive values of 87 and 93% at cut-off values > 8.7 and 9.1%, respectively. The AUC for predicting the primary outcome was highest for DE, followed by PIC-TF, CT score, and SpO2 ( Figure 2B ).

AUC analysis for DE < 15 mm and PIC-TF > 9% combination revealed that this combination had a negative predictive value of 100%; however, it did not improve the specificity (92%). Figure 3 shows a proposed stepwise approach to evaluating the intercostal muscles and diaphragm using ultrasound.

Among patients with severe COVID-19, PIC-TF had a good ability to predict NIV failure, which was higher than the CT score and SpO2, and close to DE. Two mechanisms explain our findings. First, extra-diaphragmatic inspiratory accessory muscle activity reflects respiratory load. High activity of accessory muscles in respiratory failure has been reported in electromyographic studies [5] . Second, diaphragmatic dysfunction has been reported in patients with COVID-19 [3, 4] and increased intercostal muscle thickening is a compensatory mechanism for diaphragmatic dysfunction [5] .

The few available reports on intercostal muscle ultrasound showed a dose-response relationship between PIC-TF and respiratory capacity load balance during weaning [5] ; however, this has not been previously explored in COVID-19. We found that both PIC-TF and DE could accurately predict NIV failure and/or in-hospital mortality. However, the intercostal muscles are more accessible and easier to examine than the diaphragm [5] .

Despite the good outcomes of NIV in COVID-19, delayed detection of its failure carries serious hazards, such as patient-induced lung injury due to exaggerated swings in the pleural pressure due to high inspiratory efforts, alveolar flooding, and pulmonary oedema due to increased transmural pressure in lung vessels, unplanned emergency intubation which is life-threatening to the patient [2] , and carries the risk of disease transmission to healthcare providers. Therefore, it is essential to have easy and accurate monitoring tools to determine the optimal timing of invasive ventilation. Our study provides a novel, easy, and accurate tool for monitoring respiratory drive and is the first to evaluate PIC-TF during NIV. A PIC-TF > 9% can predict NIV failure, with a 

The use of non-invasive ventilation in COVID-19: A systematic review

Noninvasive respiratory support for acute respiratory failure due to COVID-19

Diaphragmatic excursion: A possible key player for predicting successful weaning in patients with severe COVID-19

The novel use of diaphragmatic excursion on hospital admission to predict the need for ventilatory support in patients with coronavirus disease 2019

Usefulness of Parasternal Intercostal Muscle Ultrasound during Weaning from Mechanical Ventilation