Study of Respiratory Mechanics using Ultrasound in Acute Respiratory Failure before and after Non-Invasive Ventilation

Study title: Study of Respiratory Mechanics using Ultrasound in Acute Respiratory Failure before and after Non-Invasive Ventilation

Study Aim: The aim is to study the respiratory mechanics using ultrasound in patients with Acute Respiratory Failure before and after institution of Non-Invasive Ventilation.

Study Design: Prospective, observational single centre study

Study Area: Intensive Care Unit, Artemis Hospitals, Gurgaon; a tertiary care centre

Study Duration: 18 months

Sample size: 65 patients

Inclusion criteria: Patients admitted in Intensive Care Unit (ICU) with acute respiratory failure (PaO2/FiO2 <300), including Type I Respiratory Failure, Type II Respiratory Failure and patients with increased work of breathing, and scheduled for Non-invasive ventilation (NIV) trial.

Exclusion criteria: Patient refusal, Age less than 18 years, all contraindications to NIV, Non-compliance to NIV, patients on domiciliary NIV support, patients with chest wall deformity, patients with recent history of chest or abdominal surgery (within 1 month), any structural change in chest and abdomen ultrasound which confound the ultrasound parameters, poor echogenic window, obesity (BMI> 35kg/m2), pregnant patients, patients with pre-existing Diaphragm paralysis, patients with pre-existing Neuromuscular disorders, patients with history of diaphragm surgery, patients who refused for invasive mechanical ventilation, and patients requiring planed intubation for any procedure or surgery.

Parameters to be measured: Respiratory parameters (respiratory rate, use of accessory muscles), Hemodynamic parameters (Heart rate, Blood pressure, Oxygen saturation), Arterial blood analysis parameters (partial pressure of oxygen-PaO2, partial pressure of carbon dioxide-PaCO2, fraction of inspired oxygen-FiO2, bicarbonate levels, PaO2/FiO2 ratio), Ultrasound parameters (lung ultrasound score, diaphragm excursion, diaphragm thickening fraction, parasternal intercostal muscle thickening fraction, and expiratory abdominal muscle thickening fraction), and Ventilator parameters (FiO2, PEEP, PS over PEEP,  Ppeak) at baseline, and at 6,12,24,48 hours.

Outcome measures: Changes in lung ultrasound score, diaphragm excursion, diaphragm thickening fraction, parasternal intercostal muscle thickening fraction, and expiratory abdominal muscle thickening fraction after institution of NIV. Association of these parameters with NIV failure, ICU stay duration, hospital stay duration and ICU & in-hospital mortality.

Statistical analysis: The data will be entered in Microsoft Excel and statistical analysis will be done using Statistical Package for Social Sciences (SPSS) software version version 23 (IBM Corp.). Appropriate statistical tests will be applied according to the nature of the data. P value <0.05 will be considered as statistically significant