Perspiratio insensibilis and fluid and electrolyte balance in intensive care: a systematic review

Abstract Introduction In the field of intensive care, accurate measurement of perspiratio insensibilis, or insensible fluid loss, is crucial for managing fluid and electrolyte balance. While numerous studies have attempted to quantify this loss, the resulting formulas have varied widely. This inconsistency can significantly impact clinical decision-making regarding volume support and diuretic therapy. Aim This systematic review aims to investigate the available literature regarding the calculation of perspiratio insensibilis in daily water balance assessments in intensive care units (ICUs) and to identify the gold standard for its measurement. Method A systematic search of scientific databases including PubMed, Embase, CINAHL, and Scopus was conducted from December 2023 to January 2024. Studies that involved adult ICU patients (≥ 18 years) and examined fluid balance with and without the inclusion of perspiratio insensibilis were included. Exclusion criteria encompassed pediatric studies, non-ICU settings, and non-research publications. Results Five prospective observational studies published between 2004 and 2016 met the inclusion criteria, with sample sizes ranging from 15 to 151 patients. All studies primarily aimed to compare fluid-electrolyte balance data with changes in body weight, with only one study excluding perspiratio insensibilis from its calculations. Various formulas for estimating insensible losses were employed, revealing significant variability. Conclusions While it is clear that perspiratio insensibilis should be included in ICU fluid balance calculations, the most reliable measurement method remains undetermined. Further research is necessary to establish a standardized approach to calculating insensible losses.