Comparison of the effect of Non-Invasive Ventilation (NIV) and Venturi mask on Impulse Oscillometry (IOS) parameters in hospitalized patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease (COPD)

Comparison of the effect of non-invasive ventilation (NIV) and Venturi mask on impulse oscillometry (IOS) parameters in hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease (COPD)

A phase 3, randomized, double-blind, parallel-group, clinical trial conducted on 60 patients. Permuted block randomization will be used for randomization.

This study is conducted as a clinical trial (double-blind) on hospitalized patients with acute exacerbation of chronic obstructive pulmonary disease visiting Masih Daneshvari Hospital in Tehran. In the NIV group, patients receive non-invasive ventilation with an appropriate mask, and in the Venturi group, they receive oxygen through a Venturi mask.

Inclusion criteria for the study include increased shortness of breath, increased sputum volume or purulence, and oxygen saturation below 88%, arterial blood gas with pH greater than or equal to 7.30 and PaCO₂ greater than or equal to 45 mmHg, and the ability to perform the IOS test. Exclusion criteria include severe acidosis, respiratory arrest or immediate need for intubation, severe hemodynamic instability, need for invasive ventilation, presence of lobar consolidation, active pneumothorax, and very high BMI.

In the NIV group, patients were placed on non-invasive ventilation with an appropriate mask and positive airway pressure during inspiration (IPAP) of 10–14 cm H2O, positive airway pressure during expiration of 4–6 cm H2O, and the fraction of inspired oxygen was adjusted to a range of 88–92%. In the Venturi group, patients were placed on a Venturi mask with blood oxygen saturation (O2sat) maintained at 88 to 92%.

Total airway resistance, central airway resistance, reactivity at 5 Hertz, resonance frequency, reactance area

The method used is permuted block randomization. For this purpose, two treatment groups, A and B, are defined in blocks as AB and BA. Then, numbers from a random table in the range 0 to 9 are considered. Numbers 0 to 4 are assigned to block AB, and numbers 5 to 9 are assigned to block BA. Random numbers are then selected from the table. If the number 0 appears, it corresponds to block AB, and therefore two individuals enter this block, such that the first individual receives treatment A and the second individual receives treatment B. In the same way, the treatment groups for the remaining participants are determined. Although in this method the number of observations in both groups will be equal, because of the small block sizes, there is a high probability that the person conducting the study may predict the treatment group assignment. To solve this problem, the randomization list is prepared before the start of the study by a blinded individual who is not part of the treatment team. Additionally, the block sizes will be increased.

To ensure blinding, patients are placed in separate rooms and are unaware of their group assignment. Additionally, the operator responsible for performing Impulse Oscillometry is different from the nurse who sets up the non-invasive ventilation or Venturi mask for the patient. This operator is blinded to the patient grouping during the Impulse Oscillometry test, which is conducted in a location separate from the intervention site. Furthermore, the data analyst will only have access to coded data (Group A and Group B) and will remain blinded to the nature of the groups until the end of the statistical analysis process.