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Introduction

Acquired Brain Injury (ABI) includes a variety of traumatic or non-traumatic acute brain lesions characterized by the onset of a variably long-lasting state of coma (Glasgow Coma Scale ≤ 8) together with motor, sensory, cognitive and/or behavioral impairment. ABI can disrupt the brain’s arousal and awareness systems. The most severe injuries result in prolonged disorders of con-sciousness (DOCs), including unresponsive wakefulness syndrome (UWS) and minimally conscious state (MCS).

One of the main problems in rehabilitation is the management of nutrition, hampered by dysphagia, gastroparesis, tracheostomy tube, cognitive and postural-motor alterations. Therefore, an artificial nutrition must be started to provide the necessary caloric and nutrient intake.^[1,2] If long-term artificial nutrition is needed, it is good practice to prefer the enteral way by means of a PEG (Percutaneous Endoscopic Gastrostomy) rather than a nasogastric tube (NGT); enteral nutrition through PEG can be continuous or intermittent (in boluses). The latter is not without risks, especially of inhalation and subsequent aspiration pneumonia.

In literature data about patients with disorders of consciousness are limited in terms of inhalation risk and speed of administration of enteral nutrition;^[3–5] most of the studies evaluate patients affected by various conditions, but few analyze patients with ABI and DOCs.^[6] It has been assumed that there is a percentage of cases ranging between 25% and 48% that need enteral feeding after brain injury.^[7,8] Medical complications, in all patients with ABI during the rehabilitation phase, reach a frequency of 0.40/week/patient.^[9] Lung infections occur in 16% of patients with DOCs^[10] in the early rehabilitation phase and inhalation pneumonia represents 4.5% of the causes of death in these patients.^[11]

Among elderly patients with NGT the enteral feeding modality (continuous vs intermittent bolus) does not influence the frequency of lung complications or mortality^[12] and the transition from intermittent to continuous modality does not alleviate diarrhea.^[13] In trauma patients with critical illness the nutritional goal is achieved within 7 days with both modalities of nutrition (continuous or intermittent), but the intermittent management allows to reach it earlier and is logistically simpler.^[4] The nutrition-fasting alternation has cerebral activation effects resulting from gastric filling and central neuromodulation effects resulting from the secretion of ghrelin, a hormone produced by the digestive tract during fasting; in addition, gastric stagnation significantly increases the risk of bacterial growth.

Posture is also an important factor to consider during enteral feeding and is part of a bundle of evidence-based practices for a safe and effective nutritional strategy. Good practice recom-mendations prescribe a raised position at least 30 degrees during enteral feeding.^[14] The vertical position reduces the probability of gastroesophageal reflux, both with nasogastric tube in place and with tube removed^[15] and significantly reduces (26%) the probability of nosocomial pneumonia.^[16] The supine position increases the risk of apneas and hypopneas and most respiratory abnormalities during sleep occur in the supine posture.^[17,18] During an apnea, intra-esophageal pressure decreases and facilitates reflux episodes.^[19] There is evidence that patients with obstructive sleep apnea (OSA) have multiple nocturnal reflux events.^[20,21]

Furthermore, it has been shown that an early verticalization improves arousal in patients with DOCs, increasing the frequency and the level of behavioral responses.^[22,23] Both verticalization and periodical nutrition can influence circadian rhythms that have shown to be disrupted in ABI. It is common experience that circadian rhythms in such patients are altered^[24] by anatomical-functional dysfunctions of the endogenous regulation system of circadian rhythms and by reduction in external synchronizing systems, a condition often occurring in hospital settings.

Therefore, it can be assumed that interventions aimed at stimulating and regulating the plasticity of the circadian function, through periodic signals modulated by the external environment, can facilitate the reorganization of normal rhythms;^[25] the more manageable external signals are feed and motor rhythms as well as the sleep-wake rhythm. Bolus nutrition modalities and a sitting position during meals are more similar to the feeding patterns of healthy people than continuous nutrition, allowing the patients to experience more physiological and rhythmic bowel functions. Moreover, this management should decrease lung infections rate in patients with ABI and DOCs and promote better logistics and participation to rehabilitative and social activities, as well as a faster recovery of an adequate nutritional status, which is a basic premise to clinical stability and functional recovery.

The primary aim of this study is to estimate the incidence of respiratory infections, in a series of patients with DOCs admitted to an ABI rehabilitation unit and treated with intermittent enteral nutrition with high administration speed (> 200 ml / h), associated with a verticalized postural management (> 60 degrees from the floor). The secondary purpose is to analyze the effect of this bundle on management of patient care, nutritional profile, sleep-wake cycle, cognitive functioning and disability.

Material and Methods

This prospective case series was collected in an ABI Rehabilitation Unit, tertiary referral specialized institute in Italy. Inclusion criteria were: diagnosis of DOCs, both genders, age 18-75, all etiologies (vascular, traumatic, anoxic, infective), time from event between 1 and 4 months. Patients with unstable hemodynamic, critical illness polyneuropathy, mechanically assisted ventilation were excluded.

All patients underwent a protocol of gradual increase in nutritional speed and early verticalization; enteral nutrition was administered starting from a speed of 64 cc/h; in the absence of complications (gastroparesis, positive gastric stagnation) the rate of administration was increased every 3 days by 50 cc/h, maintaining vertical posture (trunk positioned more than 80°); a postural diary was used to monitor postures and time in and out of bed.

At baseline (T0) DRS (Disability Rating Scale)^[26,27], LCF (Levels of Cognitive Functioning)^[28,29], and CRS-R (Coma Recovery Scale – Revised)^[30–33] were administered to all patients meeting the inclusion criteria; SEPs (Somatosensorial Evoked Potentials), EEG (electroencephalography), ERPs (Event Related Potentials) and sleep evaluation with a polysomnography were performed, as well as blood tests evaluating nutritional status (lymphocyte count, creatinine, albumin, total protein transferrin, retinol binding protein, prealbumin). The percentage of time in/out of bed was recorded in the postural diary. After 6 weeks (T1) and 12 weeks (T2) the postural diary was updated and DRS, LCF and CRS-R scales were administered.

In addition, at 12 weeks a second sleep evaluation with polysomnography was performed. Between T0 and T2 the following data were recorded weekly: nutritional status, infections occurrence, feeding modality (intermittent/continuous) and speed of the enteral nutrition.

The study includes a T3 follow-up evaluation (12 months after the acute event) in which the DRS and LCF scales were administered during an outpatient visit.

Outcome measures

The primary outcome measure was the rate of inhalation episodes. The occurrence of inhalation was evaluated through clinical signs (cough, temperature, low peripheral oxygen saturation), laboratory (C-reactive protein, white blood cells count) and radiological (chest x-rays) tests.

Statistical analysis

The significance level was set at p<0.05. All statistical analyses were performed using Stata statistical software version 15 (StataCorp. 2017. Stata Statistical Software: Release 15. College Station, TX: StataCorp LLC).

Conclusion

The results of the present study indicate that a high-speed administration of enteral nutrition with trunk in vertical position (>80°) in dysphagic ABI patients by means of a PEG did not increase the risk of aspiration pneumonia.

In Memoriam

† During the preparation of this paper Elisa Maietti prematurely died. She was a brilliant statistician and an unforgettable joyful, radiant, generous and supportive colleague. This paper is dedicated to her memory.

Author Contributions

Conceptualization: V.C. and P.S.
Methodology: R.P., V.C and E.M.
Software and Formal analysis: E.M.
Validation: V.C., F.C.C. and P.S.
Investigation: V.C., A.R.P. and F.C.C.
Resources and Supervision: P.S.
Data curation: V.C., A.R.P., G.B., F.C.C. and E.M.
Writing—original draft preparation: V.C., F.C.C., P.S. and E.M.
Writing—review and editing: V.C., E.M., and P.S.
Project administration: V.C.
All authors have read and agreed to the published version of the manuscript.

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