key: cord-0751519-tpik0lv0
authors: FAYSSOIL, Abdallah; CARLIER, Robert; MANSENCAL, Nicolas; LOFASO, Frédéric; ANNANE, Djillali
title: High parasternal intercostal muscle thickening prior to intubation in COVID-19 infection
date: 2022-01-06
journal: Radiol Case Rep
DOI: 10.1016/j.radcr.2021.12.037
sha: 38f97383e1cfd5ea45d6b600656f0c6d7adc4a6f
doc_id: 751519
cord_uid: tpik0lv0

Acute hypoxemic respiratory failure (AHRF) is a major complication of COVID-19 pneumonia and parasternal intercostal muscle thickening may be used as a biomarker to assess inspiratory effort. We report the case of a high utilization of parasternal intercostal muscle prior to the introduction of invasive ventilation in a 66-year old male none vaccinated COVID -19 patient admitted in hospital because of AHRF.

Acute hypoxemic respiratory failure (AHRF) is a major complication of COVID-19 pneumonia. Parasternal intercostal muscle can be solicited to cope with the acute respiratory failure and the increased load. Ultrasound can be used to assess parasternal intercostal muscle [1] . We report the case of a high AHRF, acute hypoxemic respiratory failure; HFNC, high flow nasal cannula; TFic, parasternal muscle intercostal thickening fraction. utilization of parasternal intercostal muscle prior to the introduction of invasive ventilation in a 66-year old male none vaccinated COVID -19 patient admitted because of AHRF. Parasternal intercostal muscle was assessed using a linear probe positioned between the second and the third ribs, laterally in a sagittal plane, 3-4 cm from the sternum; the parasternal muscle was analyzed and visualized, using B mode, as a 3-layered biconcave structure ( Fig. 1 ) cle parasternal thickness was measured above the pleural line between the 2 hyper-echogenic layers. This technique is feasible and reproducible [ 2 , 3 ] . Parasternal muscle intercostal thickening fraction (TFic) was calculated from the measurement of the parasternal intercostal thickness end expiratory and the parasternal intercostal thickness end inspiratory using the following formula: TFic = (end inspiratory parasternal intercostal thickness -end expiratory para sternal intercostal thickness)/end expiratory parasternal intercostal thickness [2] .

A 66-year old male none vaccinated COVID -19 patient was admitted in ICU (Intensive Care Unit) because of acute AHRF. Laboratory confirmation for SARS-Cov-2 was done from realtime reverse transcriptase-polymerase reaction (RT-PCR) assay from nasopharyngeal swab. Chest CT scan showed significant lung features with ground glass opacities and bilateral patchy shadows (disease extent severe 50%-75%) ( Fig. 2 ) . His past medical history was pertinent for arterial hypertension, diabetes, dyslipidemia and obesity. He took daily aspirin, fibrate, angiotensin receptors blockers, thiazide diuretic, and calcium channel blockers. Diabetes was treated with insulin and metformin. He complained of fever, dyspnea occurred 10 days prior to hospital's admission. At admission in the emergency department, oxygen saturation measured with pulse oximetry was at 66%, increasing to 93% with the introduction of oxygen support (15 liters per minute) and respiratory rate was at 28 cycles/min. Heart rate was at 105 bpm and arterial systolic and diastolic blood pressures respectively 140 mmHg and 74 mmHg. A high flow nasal cannula (HFNC) (fraction of inspired oxygen FIO2 at 1.0; gas flow rate at 60 L/min) was introduced at admission in the ICU. Blood gas exchange results were as follow: pH 7.46, PCO2 5.8 kPa, PO2 13.3 kPa, bicarbonates at 32 mmol/L and lactates 2.4mmol/L. Other biological results were as follow: Nt proBNP (brain natriuretic peptid) 541 ng/L, troponin T (hs) at 25 ng/L, reduced lymphocytes (470/mm ³), creatininemia at 131 micromol/L, hemoglobin 8.2 g/gL and D-dimers at 2132 ng/mL. Electrocardiogram showed sinus rhythm with right bundle branch block. The patient was treated with steroids and antibiotics. The ROX index [5] , that is an index to predict intubation in patients on HFNC, was at 3.6. The ROX index is the ratio of oxygen saturation/FIO2 to respiratory rate [5] . Since the patient remains unstable with high rest dyspnea, at bedside, a cardiac ultrasound was performed 2 days after the ICU admission, coupled with diaphragm and parasternal ultrasound. Doppler Echocardiography disclosed normal left ventricular ejection fraction, reduced global longitudinal strain of the left ventricle (-13%) and normal left ventricular diastolic loading, and normal arterial pulmonary pressure. Diaphragm ultrasound found a right diaphragm inspiratory motion at 14 mm. We found a high utilization of the parasternal intercostal muscle attested by a parasternal intercostal muscle TFic at 11%. The respiratory function worsened despite HFNC and invasive ventilation was introduced. The evolution was unfavorable with the onset of acute respiratory distress syndrome (ARDS), pulmonary arterial hypertension without pulmonary embolism, right ventricular dilation, and acute renal failure requiring the introduction of renal replacement therapy and ventilator-associated pneumonia treated with antibiotics. Twelve days later post ICU admission, the patent died from refractory shock and multi-organ failure.

We report here the case of a high utilization of parasternal intercostal muscle prior to the introduction of invasive ventilation in a COVID-19 patient. The patient was on spontaneous ventilation and respiratory system was supplied using HFNC. Spontaneous breathing may expose patients to P-SILI (patient self-inflicted lung injury) [4] . In fact, in patients on spontaneous breathing, respiratory muscles work to provide a pressure gradient allowing the air to enter in the alveolar, via the transpulmonary pressure that is the difference between airway pressure and pleural pressure. However, the onset of vigorous breathing may induce more negative swing in the alveoli pressure in comparison with the hydrostatic trans vascular pressure; this phenomena may cause lung edema [5] . In this context, monitoring inspiratory effort may be essential to avoid lung injury aggravation in COVID-19. Since traditional invasive methods used to assess inspiratory effort that include pressure time product and work of breathing measurement require an invasive approach (esophageal and gastric pressures using catheters) and since these techniques cannot be done routinely in ICU, respiratory ultrasound may help to evaluate and monitor patients. Parasternal intercostal muscle has been used as a biomarker to assess neural respira-tory drive and respiratory effort using electromyogram [6] . Recently, ultrasound has been proposed to assess parasternal intercostal muscle [7] . In normal situations, at rest, normal end expiratory parasternal intercostal muscle thickness is at 2.8 mm whereas parasternal intercostal muscle thickening fraction (TFic) is at 3% [7] . During inspiration, parasternal intercostal muscle moves ventrally and straightens, as reported by Cala et al [2] and attested by this case report. Parasternal intercostal muscle thickening has been reported to be an index of inspiratory effort [1] .

HFNC improves oxygenation and inspiratory effort in patients with AHRF [8] . In patients with COVID-19, a reduction in oxygenation failure was found with the utilization of HFNC; however HFNC did not affect 90-days mortality [9] . Finally, a ROX index less that 3.83 at H12 in patients on HFNC was reported to predict HFNC failure [10] . In this case, the ROX index was calculated at H48 and was at 3.6. This physiological index may be coupled with parasternal ultrasound. Prospective studies are warranted to assess the potential application of parasternal intercostal ultrasound in COVID-19 patients.

In conclusion, this case illustrates the physiological process involved in severe COVID-19 patients and highlights the potential application of this technique to stratify COVID-19 patients with AHRF.

Informed consent for publication of their case was obtained from the patient.

Oesophageal pressure and respiratory muscle ultrasonographic measurements indicate inspiratory effort during pressure support ventilation

Respiratory ultrasonography of human parasternal intercostal muscle in vivo

Parasternal intercostal muscle ultrasound in chronic obstructive pulmonary disease correlates with spirometric severity

Mechanical Ventilation to Minimize Progression of Lung Injury in Acute Respiratory Failure

Negative-Pressure Pulmonary Edema

Neural respiratory drive predicts clinical deterioration and safe discharge in exacerbations of COPD

Usefulness of parasternal intercostal muscle ultrasound during weaning from mechanical ventilation

Physiologic Effects of High-Flow Nasal Cannula Oxygen in Critical Care Subjects

Benefits and risks of noninvasive oxygenation strategy in COVID-19: a multicenter, prospective cohort study (COVID-ICU) in 137 hospitals

An index combining respiratory rate and oxygenation to predict outcome of nasal high flow therapy