Review Article

Review Article WIENER KLINISCHE WOCHENSCHRIFT The Middle European Journal of Medicine Wien Klin Wochenschr (2008) 120/1–2: –17 DOI 10.1007/s00508-007-0920-2 Printed in Austria Gastrointestinal motility in acute illness Sonja Fruhwald, Peter Holzer, and Helfried Metzler Department of Anesthesiology and Intensive Care Medicine, Medical University of Graz, Graz, Austria Received August 29, 2007, accepted after revision December 19, 2007 © Springer-Verlag 2008 Einfluss akuter Erkrankungen auf die Darmmotilität intake, and an interdigestive motility pattern starting se- Zusammenfassung. Kritisch kranke Patienten lei- veral hours after a meal. Undisturbed intestinal motility den häufig unter Störungen der Darmmotilität, einerseits depends critically on a balanced interaction between in- als Folge der primären Erkrankung, welche die Aufnahme hibition and excitation, and a disturbance in this balance auf eine Intensivstation notwendig macht, andererseits leads to severe derangements of intestinal motility. The- als Komplikation des Intensivaufenthaltes. Störungen der se motility disturbances differ in clinical appearance and Darmmotilität können durch Beeinträchtigungen der mus- location but can affect all parts of the gastrointestinal kulären Funktion des Gastrointestinaltraktes, der Schritt- tract. This review focuses on select motility disturbances macherzellen des Darmes oder der nervalen Aktivität such as gastroparesis, postoperative ileus, and Ogilvie’s ausgelöst werden. Das enterale Nervensystem als neu- syndrome. Generally effective methods to treat these ronales Kontrollsystem des Darmes, enthält die größte conditions are given. Finally, we focus on special ma- Ansammlung von Nervenzellen (108 Zellen) außerhalb nagement options to prevent such motility disturbances des zentralen Nervensystems. Das enterische Nerven- or to reduce their severity. system funktioniert unabhängig vom zentralen Nerven- Key words: Intestinal motility, migrating motor com- system und generiert nach Bedarf verschiedenste Motili- plex, postoperative ileus, Ogilvie’s syndrome, and proki- tätsmuster: Die postprandiale Motilität beginnt nach der netic drugs. Nahrungsaufnahme, die interdigestive Motilität startet einige Stunden nach dem Essen. Wichtig für eine unge- störte Motilität ist die balancierte Interaktion zwischen Introduction hemmenden und stimulierenden Einflüssen. Kommt The gastrointestinal tract subserves a number of im- dieses Gleichgewicht aus dem Lot, sind schwere Darm- portant functions. The gut is the largest lymphoid organ motilitätsstörungen, welche sich nach ihrem klinischen and acts as a barrier to prevent abnormal absorption of Erscheinungsbild und ihrer Ausbreitung unterscheiden, intraluminal microbes and their products [1]. Its best- die Folge. Diese Übersichtsarbeit befasst sich mit dem known function, however, is digestion and absorption of Erscheinungsbild spezieller Motilitätsstörungen (Gastro- nutrients and water. In order to exert this function intes- parese, Postoperativer Ileus und Ogilvie Syndrom) sowie tinal motility is of outstanding importance. The enteric mit allgemeinen und speziellen Therapieoptionen, um die nervous system, the largest accumulation of neurons out- Häufigkeit oder den Schweregrad dieser Motilitätsstörun- side the brain, initiates and regulates these intestinal mo- gen zu reduzieren. tility patterns [2]. Most clinicians are not aware that the number of patients developing intestinal motility disturbances ex- Summary. Critical illness affects gastrointestinal ceeds all expectations. Both the acute illness itself and motility – not only as a primary problem, which brings the therapeutic interventions affect gastrointestinal motility patient to the intensive care unit (ICU), but also as a [3]. For example, gastric emptying is delayed in around complication consecutive to the ICU stay. Motility distur- 50% of mechanically ventilated patients and in about 80% bances may result from impaired function of gastrointes- of patients with head injury [4, 5]. Not surprisingly, ab- tinal muscle, pacemaker cell function and nerve activity. dominal surgery is a major contributor to intestinal motil- The most important neural control system is the enteric ity disturbances, as well as hemodynamic instability, nervous system that contains the largest collection of burns, electrolyte disorders, volume overload, and the neurons (108 cells) outside the central nervous system. need for vasoactive drugs or analgosedation []. All these Through its organization it can operate independently of factors weaken the natural defense of the gastrointestinal the brain and generate motility patterns according to tract, resulting in overgrowth of intestinal bacteria, in- need: a postprandial motility pattern starting after food creased epithelial permeability and bacterial translocation Fruhwald et al., Gastrointestinal motility in acute illness 7 leading to increased risk for systemic infections, sepsis stomach and progresses to the distal ileum. The interdi- and multiple organ failure [3, 7]. Efforts to prevent and gestive motility pattern consists of three different phases treat this potentially life-threatening situation include that are repeated approximately every two hours. Previ- early enteral nutrition, but the latter requires an undis- ously, only phase III was referred to as the MMC, but now turbed intestinal motility. all three phases of interdigestive motility are subsumed Recently published findings have provided new in- under this term: sights into intestinal motility patterns and possible therapeutic interventions. The current review focuses on clini- • Phase I is a period of quiescence (45–0 min); cally important gastrointestinal motility disturbances, • Phase II is a period of irregular contractions with a evaluates underlying causes and pathophysiologic pro- duration of 30–45 min; cesses, and discusses their clinical impact and currently • Phase III is a period of regular, propulsive activity available therapeutic options. starting in the antrum of the stomach, which moves to the distal ileum within 15 minutes [12]. Normal intestinal motility The MMC is initiated entirely by the enteric nervous system, while the rhythm of phase III activity comes from The role of the enteric nervous system the interstitial cells of Cajal known as the “pacemaker Gastrointestinal motility is governed by multiple con- cells of the gut” [13]. They are present as networks of trol systems: the central, autonomic and enteric nervous cells associated with the neural plexuses within the gut systems, endocrine cells, interstitial cells of Cajal and musculature, where they are connected to each other smooth muscle [2]. We will focus here on the most im- through long processes via gap junctions [14]. Although portant control system of propulsive motility, the enteric interstitial cells of Cajal are present throughout the gas- nervous system, which is the largest collection of neurons trointestinal tract, the key pacemaker cells for normal (108 cells) outside the central nervous system. Extending phase III activity are located along the greater curvature from the esophagus to the internal anal sphincter, the of the gastric body where they initiate slow waves of neurons of the enteric nervous system are arranged in two depolarization at a frequency of three cycles per minute ganglionated nerve plexuses [2, 8]. The myenteric plexus in the stomach and 12 per minute in the small intestine is located between the longitudinal and the circular mus- [15, 1]. The MMC remains undisturbed after vagotomy cle layer and regulates mainly motility, while the submu- or sympathectomy, but is abolished in regions of the in- cous plexus between the circular muscle and the mucosa testine in which the enteric nervous system has been inter- regulates mucosal processes (electrolyte and fluid secre- rupted [17, 18]. One of the MMC-regulating peptides is tion, mucosal blood flow and neuroimmune interactions) motilin. Intravenous administration of this peptide or of [9]. The organization of the enteric nervous system and the motilin receptor agonist erythromycin initiates phase its ability to generate different motility patterns is inde- III activity in the antroduodenal region, while somatosta- pendent of the central nervous system [2]. This autonomy tin and other substances can initiate phase III activity in of the enteric nervous system is due to the presence of the duodenum [19]. The duration of the MMC phases local motor circuits consisting of sensory neurons (intrin- shows enormous inter- and intra-individual variability sic primary afferent neurons), interneurons, excitatory and [19]. There also seems to be a day-night rhythm, as phas- inhibitory motor neurons [10]. es I and III are more frequent during the night and, in The primary transmitters of excitatory motor neurons particular, phase III lasts longer and has a lower amplitude are acetylcholine and substance P, whereas the transmit- than during the day [20]. ters of inhibitory motor neurons are nitric oxide (NO), A normal MMC pattern, also called the “housekeeper vasoactive intestinal peptide and adenosine triphosphate of the gut”, is important for the purging of the small [2]. Inhibition of muscle activity is the dominating effect bowel. During phase III, remaining food particles and of enteric nervous system output: contraction can occur indigestible residues as well as gastrointestinal secretions only in segments in which ongoing inhibition has been are swept to the distal part of the small bowel

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