1 Intensive Therapy Unit, Royal Liverpool University Hospital, Prescot Street, Liverpool, L7 8XP, UK. 2 Pinderfields General Hospital, Wakefield, UK
*Corresponding author. E-mail: Fred.Mostafa@rlbuht.nhs.uk An abstract of a part of this paper has been presented at the European Society of Intensive Care Medicine in Rome, October 2000 (published in Intensive Care Medicine: Mostafa SM and Ritchie G. Failure to wean critically ill patients from mechanical ventilation due to constipation (A). Intensive Care Medicine 2000, 26 (Suppl. 3): S336), and at the Intensive Care Society meeting in London, December 2000 (published in the British Journal of Anaesthesia: Mostafa SM, Bhandari S, Ritchie G. Constipation and its implications in the critically ill: A National Survey of United Kingdom Intensive Care Units (A). British Journal of Anaesthesia 2001; 87: 343P).
Accepted for publication: June 21, 2003
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Abstract |
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Method. We prospectively studied constipation in an intensive care unit of a university hospital, and conducted a national survey to assess the generalizability of our findings.
Results. Constipation occurred in 83% of the patients. More constipated patients (42.5%) failed to wean from mechanical ventilation than non-constipated patients (0%), P<0.05. The median length of stay in intensive care and the proportion of patients who failed to feed enterally were greater in constipated than non-constipated patients (10 vs 6.5 days and 27.5 vs 12.5%, respectively (NS)). The survey found similar observations in other units. Delays in weaning from mechanical ventilation and enteral feeding were reported by 28 and 48% of the units surveyed, respectively.
Conclusions. Constipation has implications for the critically ill.
Br J Anaesth 2003; 91: 81519
Keywords: complications, constipation; intensive care, audit; ventilation
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Introduction |
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Defecation is a basic body function, but staff in intensive care units (ICUs) that monitor gastrointestinal functions record features such as volume of gastric aspirate and occurrence of bowel opening rather than its absence, that is constipation. Because of shift working, several nurses care for the same patient and it is not surprising that it can be difficult to maintain a record of this function. Consequently, the occurrence of constipation and its implications in critically ill patients may be overlooked. Although constipation is a known health problem for elderly hospitalized patients,5 we found no published information about constipation, its hazards, or bowel management in the critically ill patient.
We therefore conducted a prospective study of the incidence of constipation and its implications on the progress of critically ill patients, and a national survey to determine whether such a problem is common in other ICUs in the UK.
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Methods |
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Constipation was defined as failure of the bowel to open for three consecutive days.4 We recorded patients age, sex, APACHE II score, length of stay in ICU (LOS), diagnosis and outcome, and the incidence and duration of constipation episodes. We noted the ability of patients to enterally feed or wean from mechanical ventilation. Failure to feed was defined as stopping of enteral feeding because of large gastric aspirates (when the volume of fluid aspirated after a 46 h feeding period, which was tried again after a rest period of 46 h, was more than 50% of the volume administered) or repeated vomiting. Metoclopramide 10 mg and, if unsuccessful, erythromycin 125 mg were given intravenously if poor upper intestinal motility was suspected.
Weaning from mechanical ventilation was started when the cause or disease process necessitating mechanical ventilation had significantly improved or resolved, gas exchange was adequate (arterial oxygen tension >8 kPa and inspired oxygen fraction <0.5), sedation was being reduced with appropriate neurological and muscular status, cardiovascular function was stable, and the patient was considered ready to wean.6 Failure of weaning (to reduce or discontinue ventilatory support or a trial of spontaneous breathing) was recorded if a patient had any of the following: ventilatory frequency more than 35 bpm, arterial oxygen saturation less than 90%, heart rate more than140 beats min1 or less than 20% sustained increase or decrease in heart rate, or systolic arterial pressure more than 180 mm Hg, or agitation, anxiety, or sweating.7
MannWhitney and Fishers exact tests were used for statistical analysis.
The questionnaire for the national survey (Appendix) was designed to investigate four areas of interest: (i) the characteristics of the ICU, such as the type of unit and the number of admissions, patients age and APACHE II score; (ii) if constipation was a problem in the ICU and if the unit had a protocol for its management; (iii) the incidence of constipation and its prophylaxis in ICU; (iv) complications of constipation. The survey was sent to 250 ICUs in the UK.
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Results |
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The response rate to the survey was 57% (143 replies). Only 14% were specialized ICUs, the remainder (86%) were general units. Forty-eight units admitted more than 400 patients, 74 units admitted between 200 and 400, and 14 admitted less than 200 patients per year. The rate was not known in the remaining seven units. Median age and APACHE II score were 60 yr (range 4576) and 18 (829), respectively.
Only 16 of the 143 units had protocols for enteral feeding. Although 75 of the units considered constipation a problem, only five had guidelines for its management (Table 3). The most commonly used laxatives were osmotic (93 units) and the least were bulk-forming agents (25 units) (Table 4). Gastro-enterologists or surgeons were involved in the management of constipated patients in only 38 units.
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Discussion |
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If enteral feeding were not given, more of our patients could have become constipated. However, enteral feeding was attempted in all patients and only 11 patients out of 40 with constipation failed to feed. The incidence of constipation, however, in this study was great (83%) despite excluding patients who had recent bowel surgery. This incidence may have been because our unit did not have a protocol for the management of constipation, but both constipated patients (26 cases) and non-constipated patients (4) had bowel care in the form of laxatives and prokinetic agents. We know of only one other study in intensive care patients, which reported an incidence of constipation of 16%. The study was a multicentre trial of enteral nutrition and constipation was defined as the need for treatment according to the treating physicians criteria for constipation.12 In our study patients were treated similarly according to standard protocols for feeding, weaning from mechanical ventilation, sedation, and cardiovascular support. Fluid and electrolyte balance was measured daily and promptly treated, and the patients were haemodynamically stable.13
The critically ill patient may become constipated for several reasons. Sedatives, particularly opiates, can decrease gut motility,14 but we found similar use of these agents in patients with and without constipation. Immobility, dehydration, lack of fibre in diet, and factors such as lack of access to appropriate facilities can also lead to constipation.5 In addition, critically ill patients cannot mobilize to the toilet, respond to the urge, or strain to defecate.
Constipation can cause abdominal distension, vomiting, restlessness, gut obstruction, and perforation. It is associated with fatal pulmonary embolism.15 We conducted this study partly because two patients in our unit developed large bowel perforation because of constipation despite attempts to alleviate the problem. The small size of the study caused by limiting the duration of the study to 3 months, may explain the lack of significance in LOS and failure to feed in the constipated patients, and the similar mortality. The high incidence of constipation that we found persuaded us to stop the study and start a treatment regime, which was set up with the help of the gastroenterologists.
We have noted that 42% of constipated patients failed to wean from mechanical ventilation, which was significantly more than in the non-constipated patients. Other factors may account for failure to wean, but weaning was protocol driven and clinically appropriate. A weaning protocol reduces the duration of mechanical ventilation and increases the probability of weaning.6 Distension, discomfort, and restlessness from constipation could explain failure to wean. This failure could be the inability of the ventilatory muscle function to cope with increased workload caused by distension from constipation. Patients who failed to wean had objective criteria for stopping a weaning trial such as rapid shallow breathing, which is a good indicator of weaning failure.16
The response to the survey was modest. Nevertheless, over 140 ICUs responded. The survey confirms a high prevalence of constipation in critically ill patients, with little attention to large bowel dysfunction. The definition of constipation in our survey was kept simple to encourage adequate responses. Many units used several types of laxatives (Table 4), but 8% of the units did not use any prophylaxis. Few ICUs (26.6%) involved other specialties to address the problem. Constipation does not always respond to a particular laxative, and osmotic laxatives (such as lactulose), which were the most commonly used laxatives in the survey, can cause more distension and discomfort,17 perhaps making weaning from mechanical ventilation more difficult. Laxative agents, with an osmotic action, may be harmful in the critically ill as they can affect fluid balance.17
Constipation delayed enteral feeding in nearly 50% of the units surveyed. Some ICUs reported delayed weaning from mechanical ventilation, and even discharge from intensive care, because of constipation. This may delay the patient recovery. Constipation can also indicate colonic pseudo-obstruction, which can cause gut perforation and peritonitis, and requires specific investigations and management.18 The lack of involvement of gastroenterologists (in nearly 75% of ICUs surveyed) in managing this condition is a matter of concern. The management of constipation may be given low priority in the acute care of the critically ill patient, but persistent constipation could delay progress, cause debilitation and increase length of stay. Guidelines to prevent, detect, and manage constipation in the critically ill are needed. Further investigation of the condition, its aetiology and management is warranted.
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Acknowledgements |
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References |
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