| Background of the study. Intra abdominal pressure (IAP) theoretically may be a predictor of enteral nutrition tolerance (EN). Urinary bladder pressure (UBP) is the gold standard for estimating IAP. Current recommendations for UBP measurement (UBPM) calls for the instillation of normal sterile saline (NSS) into the bladder while the patient is supine with a zero degree (0°) head of bed elevation (HOBE). How different instill volumes (IVs) and body positions influence UBPM were unknown, and the intra- and inter-observer reliability had not been adequately investigated.;Specific aims. (1) Systematically evaluate the relative contribution of bladder IV and subject's position upon UBPM. (2) Determine inter- and intra-observer reliability of UBPM. (3) Identify other factors that may influence IAP and UBPM: age, gender, Body Mass Index (BMI), net fluid balance (NFB), positive airway pressure, use of paralytic agents, EN and length of stay (LOS). Method. Prospective randomized study of 120 critically-ill adults who had UBPMs taken in four different positions and before and after three different IVs. All UBPMs except 20 were obtained by the principle investigator (PI). To determine inter-and intra-observer reliability the PI and a nurse co-investigator obtained 20 UBPMs each in 10 subjects.;Results. Two way ANOVA showed a significant volume (p<0.053), position (p<0.007) and volume-position interaction (p<0.004). 200 ml IVs gave higher UBP estimates and variability, 0 ml IV gave lower UBP estimates, high variability and occasional negative values. The supine-0° HOBE yielded lower values. No statistically significant difference in UBP was observed among the three positions that were with a 30° HOBE when measured with a 25 ml IV. Intra-and inter-observer reliability was high. BMI, NFB, LOS, and EN use were found to be predictors of UBP.;Significance to nursing. The findings of this study impacts critical care (CC) nurses' bedside practice by contributing data to develop an evidenced based UBPM procedure. It also allows for further investigation of the relationship between increased IAP and the gastrointestinal tract in critical illness and will facilitate the exploration of the relationship between increased IAP and EN tolerance. |
