| dc.description.abstract | Background: Reflux of gastric contents in gastric fed patients is a contributor to pulmonary aspiration. Aspiration events are reported in approximately 50-75% of patients with endotracheal tubes. Aspiration of oral and gastric secretions in ventilated patients is a major cause of ventilator associated pneumonia (VAP). Guidelines that recommend head of bed (HOB) elevation greater than 30◦ to prevent reflux, aspiration and VAP conflict with guidelines to prevent pressure ulcers which recommend HOB elevation no greater than 30◦. Studies are lacking on direct comparison of HOB elevation at 30◦and 45◦ for reflux, aspiration and pressure ulcer outcomes simultaneously. Esophageal probe pH measures are used to detect reflux. No studies have examined the predictive relationship of reflux and aspiration in mechanically ventilated gastric fed patients or the role of pH measurement at the bedside with pH paper to detect gastric reflux. Purpose: This study had 6 aims: 1) To describe the frequency and duration to which patients¡¯ HOB angles are temporarily lowered for treatment purposes below 30◦ or below 45◦, 2) To describe the occurrence of reflux (pepsin-positive oral secretions) and aspiration (pepsin-positive tracheal secretions) with HOB elevation at 30◦ and 45◦, 3) To determine the association between reflux and aspiration with the 2 different HOB elevations in adult intensive care unit (ICU) mechanically ventilated gastric fed patients, 4) To determine the association between a temporarily lowered HOB position for treatment purposes and reflux of gastric contents, 5) To determine the association between 7 patient characteristics (gender, age, body mass index, gastric residual volume, sedation level, disease severity, and use of prokinetic agents) and reflux, 6) To determine the association between the pH (range 0-14) of oral secretions and pepsin presence in oral secretions. Methodology: Human Research Protection Office approval was obtained. Consent was acquired from patient surrogates the day prior to enrollment in the study. A randomized 2-day crossover trial was conducted in a surgical and medical ICU. Mechanically ventilated gastric fed subjects were randomly assigned to 1 of the 2 HOB elevation sequences, HOB 30◦ for 12 hours (hrs) on day 1 and 45◦ for 12 hrs on day 2 or HOB at 45◦ for 12 hrs on day 1 and 30◦ for 12 hrs on day 2. A HOB measurement device stored HOB angles every 30 seconds over the 36 hrs. Subject preferences for positioning for comfort were considered and HOB was lowered at any time by clinicians as the clinical situation warranted or during procedures and diagnostic tests. Usual care for the elevation of the HOB was considered 30◦ and experimental was 45◦. Oral secretions were obtained hourly or as needed and tracheal secretions every 2 hrs or as needed. All samples of oral secretions were examined for the presence of pepsin and pH measurement. Subjects were repositioned every 2 hrs as their condition allowed. Skin assessment of sacral/coccyx and greater trochanter areas were assessed for pressure ulcers every 2 hrs with each reposition. Data were analyzed using Wilcoxon Signed Rank Tests, Friedman tests for repeated measures and Kendall¡¯s tau correlations. Results: Fifteen subjects were enrolled; 11 subjects completed both days, 4 subjects had partial data collection due to endotracheal tube removal. The total number of hrs was 150 hrs at 30◦ and 160 hrs at 45◦. No subjects developed pressure ulcers per National Pressure Ulcer Advisory Panel staging guidelines. Subjects were maintained at 30◦ for 96% of possible minutes and at 45◦ for 77% of possible minutes (p = .035). The mean HOB angle when lowered was 8.2◦ in the 30◦ condition and 19.4◦ in the 45◦ condition (p = .008). Subjects¡¯ HOB angles were lowered 66 times (mean = 4.7/patient) in the 30◦ hrs and 76 times (mean = 5/patient) in the 45◦ hrs. Overall mean angle for HOB was 30◦ for usual care hrs and 39◦ for the experimental hrs. A total of 188 oral secretions were obtained, 106 (56%) were pepsin-negative and 82 (44%) were pepsin-positive. A total of 174 tracheal secretions were obtained, 66 (38%) were pepsin-negative and 108 (62%) were pepsin-positive. No significant association was found with the minutes the HOB was lowered or the mean angle when lowered and percent pepsin-positive oral secretions. Mean HOB angle on each day was significantly negatively correlated with percent pepsin-positive oral secretions. The mean percent of pepsin-positive oral secretions was not significantly higher (p=.108) at 30◦ HOB elevation (48.4 ¡À 31.3) compared to 45◦ HOB elevation (32.3 ¡À 33.2). The mean percent of pepsin-positive tracheal secretions was not significantly higher (p = .366) at 30◦ HOB elevation (69.4 ¡À 33.8) than 45◦ HOB elevation (62.5 ¡À 34.5). The median frequency that oral secretions were obtained, (mean, SD, median) 8.5 ¡À 3.6, 9.5 at 30◦ and 5.7 ¡À 3.2, 5, at 45◦, was significantly lower at 45◦ (p = .035). The only significant patient characteristic in relationship to the percent of pepsin-positive oral secretions was deeper sedation. No relationship between reflux and aspiration or pH measures and reflux were found. Conclusions: With the cross over design of 15 subjects, the number of oral and tracheal specimens collected provided over 360 samples. Lower mean HOB angles as well as deeper sedation levels were associated with a significantly higher frequency of reflux. Results of this study provide evidence that HOB positioning 30◦ is feasible and superior to HOB ¡Ü 30◦ in mechanically ventilated gastric fed ICU patients to reduce reflux and aspiration without development of pressure ulcers. | |
