Application and calculation methods of dynamic compliance in anaesthetised dogs, a scoping review

To record the terms, definitions, and abbreviations used in the literature, investigate the rationale for employing dynamic compliance (C_dyn) in studies of anaesthetised dogs with mechanically ventilated lungs, and identify the methods used to calculate C_dyn.

A comprehensive search across Medline, PubMed, Scopus, and CAB Abstracts databases identified studies using keywords related to canine species, anaesthesia, C_dyn, and the respiratory system. Reference lists from recent publications (2010-2024) focusing on respiratory mechanics in dogs were also reviewed. Following duplicate removal, a two-step screening process was employed. This involved reviewing titles and abstracts, followed by full-text retrieval based on predefined eligibility criteria, concentrating on studies involving anaesthetised dogs with closed chests where C_dyn was measured. Data extraction included terms, definitions, measurement equipment, and study applications.

Of 362 initial documents, 186 duplicates were removed, leaving 176 for abstract screening. Of these, 122 full texts were retrieved, with 54 meeting inclusion criteria. Most studies were published between 1970 and 2002, with only five published after 2010. In 49/54 studies, dogs were used as animal models for translational research. Whole-body plethysmographs and pneumotachographs were commonly used to evaluate tidal volume for the calculation of C_dyn; the sampling site of airway pressure varied. In 43/54 papers, oesophageal or pleural pressure was measured to determine transpulmonary pressure, suggesting that C_dyn of the lung was monitored, although this was not always explicitly stated. The three most recent studies involved clinical patients, using C_dyn of the respiratory system displayed by respiratory modules integrated into ventilators or multiparametric physiological monitors. Future research should establish clear protocols for measuring C_dyn to enhance understanding and characterization for both research and clinical purposes.