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 papers3,4 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.