This retrospective observational study in a single-center mixed ICU demonstrates that EN interruption is frequent, relatively long, and associated with substantial calorie deficits for various reasons. Airway procedures are associated with relatively longer durations of interruption compared to other reasons. Documentation and orders are frequently missing.
Previous studies [2, 8, 9] have reported GI dysfunction and interruptions due to therapeutic procedures to be the most common reasons for EN interruption. Although the current study observed similar trends, previous studies did not categorize the procedure details [2, 8, 9], and invasive procedures were excluded [3]. To our knowledge, this is the first study to evaluate the relationship between the reasons for and duration of EN interruption.
To achieve the goal of minimizing calorie deficits while preventing EN-associated complications, nutritional protocols should focus on minimizing the interruption of nutrition along with enhancing administration. To establish an efficient interruption protocol, it is essential to evaluate the duration of the interruption for each procedure since different procedures have different safety margins for the duration of the interruption. Each interruption can be divided into several components. Whether the time of EN interruption before or after the procedure has a greater impact on nutritional deficits is a valid question since the cause for delay and the longest part of the interruption duration differs among procedures. McClave et al. investigated the durations and reasons for interruption of EN in a medical ICU [2], showing the proportion of interruption in the total duration of EN administration for an individual reason, but did not present the actual length of time for the interruption [2]. Passier et al. described the duration of interruptions, partitioning into two durations before and after the procedures, but the numbers presented in the study were only the average durations among all patients and were not individualized according to the reasons for interruption [3]. Adam et al. investigated interruptions and their reasons and energy deficits in five ICUs in the UK [8], but a thorough description of the interruption reasons was not performed in this study. In contrast with these studies, we describe the duration of the interruption for each reason, and the duration of interruptions for the procedure and from the time of the procedure to restart for each reason.
The duration of EN interruption related to either patient GI symptoms or respiratory and airway manipulations was long, and large variations found. Large variations were observed for interruptions for diagnostic tests or therapeutic interventions, both in the time from EN interruption until treatment start and the time from treatment end until EN restart. Reasons for the long, varying durations of these interruptions may be due to a lack of a clear interruption protocol, leading to a long unnecessary interruption, and a delay in early restart after a procedure. External factors including excess clinical load in the ICU and other departments involved in patient care may affect the timing of diagnostic and therapeutic procedures. Extended duration until EN restart after procedures may be due to insufficient staff awareness of the calorie deficit caused by the interruption, which might worsen patient outcomes [1]. Intervals between EN interruption and tracheostomy (5.8 [4.0–9.3] h) could be shortened in at least half of the patients, if the general consensus of a 6-h interruption before the procedure is followed. Substantial delay until restart of EN could also be improved for tracheostomy (3.2 [1.0–3.6] h), intermittent dialysis (1.0 [0.3–1.8] h), procedures outside of the ICU (1.2 [0.5–2.3] h), and ICU procedures (1.5 [0.7–3.0] h).
In this study, the average nutritional deficit due to EN interruption for the daily caloric goal was 11.5%. Adam et al. [8] reported an average deficit in prescribed calories of 24% in five facilities studied, while other studies have reported calorie deficits of 13–40% [9,10,11]. The results of the current study are better than those in previous reports, probably due to efforts to supplement substantial calorie deficits, not by reducing the duration of the interruption but by increasing the rate of administration after restarting EN. However, depending on an increased rate of administration is a potential source of GI complications of EN. In one ICU with an EN administration protocol, calorie administration was closer to prescribed targets compared to ICUs without a protocol [8]. Although details of this protocol are unknown, EN administration protocols may affect the resulting calorie deficit.
In the current study, the most common reason for EN interruption was “undetermined.” Clear orders for EN interruption and resumption were not documented in most cases. Insufficient nutrition in critically ill patients is related to increased mortality rates [1]. Many institutions adopt an efficient EN protocol for achieving calorie targets and reducing interruption by EN intolerance. However, a practical protocol for reducing interruption time due to the procedures has not yet been made available [12]. Busy ICU staff may fail to pay sufficient attention to nutritional deficits due to interruptions but would become more cautious of the interruption if a clear interruption protocol existed.
The current study has several limitations. First, a single-center design may hamper generalizability of the results. Nutritional policies and practices in an individual ICU vary and change over time. These findings may not be applicable in a substantial number of ICUs. However, it is noteworthy that even in a closed ICU as in the study institution, the absence of an interruption protocol and documentation may result in calorie deficits. These data may be of value in institutions considering implementation of a protocol, especially in open ICUs. Second, due to the retrospective study design, various errors could be possibly included. However, data from an electronic chart system, as in the current study, could allow more accurate documentation of the initiation and cessation of EN and amounts given than by a manual system.