PREVENTION OF PRESSURE ULCERS IN NASAL BRIDGE DURING NON-INVASIVE MECHANICAL VENTILATION. DISCUSSION OF RESULTS. AUTHORS’ RESPONSE TO PEÑA-OTERO ET AL.

Editor,

We would like to thank Peña-Otero et al. for their attention to our paper on the preventative effect of hydrocolloid dressings on nasal bridge pressure ulceration in acute NIV in the UMJ¹. It was not our intention to demean by any means the study by Otero et al.² by mentioning that it was a small sample study. We have used the expression ‘small sample sizes’ generically referring to two other papers^3,4 without any indication of the power analysis involved alongside the paper by Otero et al.² However, we would like to take this opportunity to clarify our standpoint on the question of sample size calculation in Otero et al². A total sample size of 152 is determined to detect an effect size of 15.8% for the stated size and power. But this sample size is valid for comparing 76 subjects in 2 groups to be able to draw the conclusion that hyperoxygenated fatty acids (HOFA) is responsible for the preventative effect rather than split over 4 groups. The pairwise comparisons as stated in Otero et al.² require a larger sample size in each group to achieve the required power of 0.8. However, we strongly feel that the study in Otero et al.² is a significant study in the area of prevention of nasal bridge pressure ulceration and we are indebted to them for a pioneering research in the field of the practical application of NIV.