Jump to: Page Content, Site Navigation, Site Search,
You are seeing this message because your web browser does not support basic web standards. Find out more about why this message is appearing and what you can do to make your experience on this site better.
Stephen J Lewis a Department of Medicine,
Addenbrooke's Hospital, Cambridge CB2 2QQ, b MRC Health Services Research
Collaboration, Department of Social Medicine, University of Bristol,
Bristol BS8 2PR, c Department of
Surgery, Bristol Royal Infirmary, Bristol BS2 8HW, d Department of
Maxillofacial Surgery, University of Bristol, Bristol BS1 2LY Correspondence
to: S Lewis sjl{at}doctors.org.uk
| |
Abstract |
|---|
|
|
|---|
Objective:
To determine whether a period of starvation (nil by mouth) after gastrointestinal surgery is beneficial in terms of
specific outcomes.
Design:
Systematic review and meta-analysis of
randomised controlled trials comparing any type of enteral feeding
started within 24 hours after surgery with nil by mouth management in elective gastrointestinal surgery. Three electronic databases (PubMed,
Embase, and the Cochrane controlled trials register) were searched,
reference lists checked, and letters requesting details of unpublished
trials and data sent to pharmaceutical companies and authors of
previous trials.
Main outcome measures:
Anastomotic dehiscence,
infection of any type, wound infection, pneumonia, intra-abdominal
abscess, length of hospital stay, and mortality.
Results:
Eleven studies with 837 patients met the
inclusion criteria. In six studies patients in the intervention group
were fed directly into the small bowel and in five studies patients were fed orally. Early feeding reduced the risk of any type of infection (relative risk 0.72, 95% confidence interval 0.54 to 0.98, P=0.036) and the mean length of stay in hospital (number of days
reduced by 0.84, 0.36 to 1.33, P=0.001). Risk reductions were also seen
for anastomotic dehiscence (0.53, 0.26 to 1.08, P=0.080), wound
infection, pneumonia, intra-abdominal abscess, and mortality, but these
failed to reach significance (P>0.10). The risk of vomiting was
increased among patients fed early (1.27, 1.01 to 1.61, P=0.046).
Conclusions:
There seems to be no clear advantage to
keeping patients nil by mouth after elective gastrointestinal
resection. Early feeding may be of benefit. An adequately powered trial
is required to confirm or refute the benefits seen in small trials.
|
What is already known on this topic
What this study adds
|
| |
Introduction |
|---|
|
|
|---|
A period of starvation ("nil by mouth") is common practice after gastrointestinal surgery during which an intestinal anastomosis has been formed. The stomach is decompressed with a nasogastric tube and intravenous fluids are given, with oral feeding being introduced as gastric dysmotility resolves.1 The rationale of nil by mouth is to prevent postoperative nausea and vomiting and to protect the anastomosis, allowing it time to heal before being stressed by food. It is, however, unclear whether deferral of enteral feeding is beneficial.
Contrary to widespread opinion, evidence from clinical studies and animal experiments suggests that initiating feeding early is advantageous. Postoperative dysmotility predominantly affects the stomach and colon, with the small bowel recovering normal function 4-8 hours after laparotomy.1 Feeding within 24 hours after laparotomy is tolerated and the feed absorbed. 2 3 Gastrointestinal surgery is often undertaken in patients who are malnourished,4-6 which in severe cases is known to increase morbidity.7 In animals, starvation reduces the collagen content in anastomotic scar tissue 8 9 and diminishes the quality of healing, 9 10 whereas feeding reverses mucosal atrophy induced by starvation11 and increases anastomotic collagen deposition and strength.12 Experimental data in both animals and humans suggest that enteral nutrition is associated with an improvement in wound healing.13 Finally, early enteral feeding may reduce septic morbidity after abdominal trauma14 and pancreatitis.15
Several clinical trials directly comparing strategies of early feeding
with nil by mouth after elective gastrointestinal surgery have been
performed. These studies, however, have not been systematically reviewed. We performed a systematic review and meta-analysis of randomised trials to assess the evidence on benefit and harm of early
enteral feeding.
| |
Methods |
|---|
|
|
|---|
Eligibility criteria and literature
search
Clinical trials were eligible if patients had undergone
elective gastrointestinal surgery and were randomly allocated to
receive either enteral feeding (within 24 hours after surgery) or the
traditional management of nil by mouth and intravenous fluids with
introduction of enteral fluids and diet as tolerated. We supplemented
computerised searches of PubMed, Embase, and the Cochrane controlled
trials register with checks of relevant reference lists. We wrote to
trialists requesting additional data on outcomes not reported in
publications and on trial methods. We also approached pharmaceutical
companies that produce enteral feeds and asked whether they held data
from unpublished trials.
Data extraction and outcomes
From each study we collected
data on the site of surgery, whether an intestinal anastomosis was formed, whether the pathology was benign or malignant, the type of feed
used, and the method of administration of the feed. The site of surgery
was classified as pancreatic, hepatobiliary, upper gastrointestinal
(proximal to the jejunum), or lower gastrointestinal (distal to the
duodenum). Outcomes potentially related to feeding included anastomotic
dehiscence, infection of any type, wound infection, pneumonia,
intra-abdominal abscess, vomiting, mortality, and length of hospital
stay. The unplanned reinsertion of a nasogastric tube was recorded. The
data were extracted independently by two of the authors (SJL and PAS),
checked for consistency by another author (ST), and sent to the
trialists for review.
Assessment of methodological quality
Two of us (ST and ME)
independently assessed the two dimensions of methodological quality that empirically have been shown to be associated with biased estimates
of treatment effects: adequacy of concealment of allocation to
treatment groups and double blinding.
16 17
Differences in assessment were resolved by consensus.
Analysis
We combined results from individual studies on the
relative risk scale using fixed effects meta-analysis.18
Data on length of hospital stay were pooled with non-standardised mean differences. We used a
2 test to test for
homogeneity of relative risks. We used funnel plots to determine the
presence of publication bias and related biases and performed a
statistical test of funnel plot asymmetry.19 In a
sensitivity analysis we excluded data from patients who did not have an
intestinal anastomosis from analyses of anastomotic dehiscences. These
patients had abdominoperineal resections or stoma creations. In a
planned subgroup analysis we examined whether the risk of anastomotic
dehiscence differed according to whether the anastomosis was proximal
or distal to the site of feeding. Results are presented as relative
risks (95% confidence intervals). All analyses were performed with
Stata version 6.0 (StataCorp, College Station, Texas).
| |
Results |
|---|
|
|
|---|
Characteristics of trials, patients, and interventions
We identified 13 randomised controlled trials, all of which were
published in English.
13 20-31
We excluded two of these
trials because no information on relevant outcomes was given, and
attempts to obtain unpublished data from the authors were
unsuccessful.
30 31
Additional unpublished data were
obtained for six of the studies.
21 22 24-26 29
The
earliest study was published in 197920; however, most were
published between 1995 and 1998.
|
Methodological quality of trials
Reporting on concealment of allocation of treatment and blinding
was poor. In three trials allocation was
concealed with sealed envelopes,
23 24 26
and one trial
used an open table with random numbers,20 but in the remaining studies the exact method of randomisation was unclear. In the
study by Heslin et al the outcomes were assessed by "a physician not
associated with the surgical team."26 In all other studies outcome assessment was probably open, although this was explicitly stated in only one report.28
Outcomes
The effects of early feeding on anastomotic dehiscence,
infections, vomiting, and mortality are detailed in table 2 and
summarised in the figure. Occurrence of anastomotic dehiscence was
reported in eight of the 11 trials. Table 3 gives detailed information
on the number of events
for example, the risk of dehiscence ranged
from 2% (2/95) to 7% (2/30) in early feeding groups and from 1%
(1/81) to 25% (4/16) in control groups. Seven trials showed that early
feeding led to a reduction in risk of anastomotic dehiscence (table 2)
with a combined relative risk of 0.53 (95% confidence interval 0.26 to
1.08, P=0.080) and no evidence of heterogeneity between studies
(
2=2.10, P=0.96). Results were similar when 31 patients in whom no anastomosis had been formed were excluded from the
denominator of five trials (combined relative risk 0.54, 0.26 to
1.09).
20 22 24 25 27
There was little evidence that
results differed between the two studies in which the anastomosis was
known to be proximal to the site of feeding
26 28
and the
six trials in which it was distal (P=0.42 for
interaction).
|
|
|
2=10.7, P=0.22). Similar reductions were
observed for wound infection and pneumonia (figure). There was an
increase in the risk of vomiting among patients fed early (1.27, 1.01 to 1.61, P=0.045). Absolute risks ranged from 21% (17/80) to 50%
(15/30) in the early feeding groups and from 14% (11/81) to 57%
(17/30) in the control groups (table 3). When nasogastric tubes were
not placed routinely at the time of surgery the rate of placement
because of nausea and vomiting was higher in patients fed early
(1.21, 0.73 to 1.99, P=0.46).
Mortality was reported in all but two studies,
21 28
but
deaths occurred in only five (table 2). When reported, death occurred in hospital except for in one study in which 30 day mortality was reported.24 Mortality ranged from none
to 7% (2/30) in the early feeding groups and 13% (4/30) in the
control groups (table 3). There were four deaths in the early feeding
groups compared with 10 deaths in control groups (relative risk 0.48, 0.18 to 1.29, P=0.15).
Length of hospital stay was reported in all 11 studies. When combining
data for meta-analysis we estimated the mean length of stay from the
median for one trial.20 We estimated standard deviations
(SD) by dividing ranges by factor 4 for two trials.
20 21
The mean length of stay ranged from 6.2 days to 14.0 days in early feeding groups and from 6.8 days to 19.0 days in control groups. Combined results showed a significant reduction by 0.84 day (0.36 to
1.33 days, P=0.001), with some evidence of heterogeneity between studies (
2=16.2, P=0.094). Results were similar
when we excluded the two trials with incomplete
data.
20 21
Two major complications of feeding were reported in patients fed via
jejunostomies: one broke and migrated into the abdomen26 and one left a prolonged fistula after it was removed.26
Funnel plots
We examined funnel plots for all nine outcomes (the seven shown in
table 2 plus length of stay and replacement of nasogastric tubes).
There was no clear evidence of asymmetry in any of these plots (P>0.10
by regression test19), except for mortality (P=0.068).
| |
Discussion |
|---|
|
|
|---|
This meta-analysis yielded three principal findings. Firstly, there does not seem to be a clear advantage in keeping patients nil by mouth after elective gastrointestinal resection. Secondly, in these patients early feeding may be beneficial. Thirdly, we believe these results indicate the necessity for an adequately powered clinical trial to assess early enteral feeding in patients undergoing elective gastrointestinal surgery.
Complications after operation
Anastomotic dehiscence is a major complication of gastrointestinal
surgery with considerable morbidity and mortality.32 The
combined estimate failed to reach conventional levels of significance but indicates that early feeding may reduce the risk of dehiscence. Reporting on factors that could have modified the effect of early feeding,32-34 such as the experience of the surgeon,
whether the resections were from the large or small bowel, the length
of the operation time, postoperative pain control, the use of
antibiotics, and the success of the operation, was incomplete.
Furthermore, the definition of dehiscence varied between trials.
However, the estimated effect in eight out of nine studies that
reported anastomotic dehiscence indicated benefit and was similar among
patients fed proximally or distally to their anastomosis.
Length of hospital stay
The length of hospital stay after surgery was reduced in eight of
the eleven studies. Overall the reduction corresponds to about one
day, which is economically important. Reduction in complication rates
may explain this observation, as might a faster return of
gastrointestinal function. Early postoperative feeding after
non-gastrointestinal surgery has also been shown to reduce length of
stay in hospital.
35 36
Although not significant, the
direction of effect suggested a reduced risk of postoperative death
among patients who received early enteral feeding in all five studies
in which mortality occurred. There were insufficient data to comment on
the causes of death. Reductions in mortality tended to be larger in
smaller studies, which may be due to chance, publication bias, or lower
methodological quality of smaller studies.19 Mortality was
one out of nine outcomes examined, and no evidence of small study bias
was evident for the other outcomes. The association found for mortality
was probably a chance finding.
Statistical quality
The 11 randomised trials identified were clinically heterogeneous
and most of them were small and of doubtful methodological quality.
Combination trials that differ in terms of underlying condition,
operation, and intervention may be inappropriate. However, we were
interested in the pragmatic comparison of early versus deferred feeding
strategies after gastrointestinal surgery and not in differences
between feed types or specific routes of feeding. It is noteworthy that
the effect of early nutrition seemed to be homogeneous across a set of
trials that were clearly heterogeneous in clinical terms. Our ability
to detect heterogeneity between trials, however, was limited by the
small number of trials and by the often inadequate reporting. For
example, definition of the patients' pre-existing nutritional state
and severity of underlying disease was generally poor. The method of
randomisation and blinding of outcome assessment was also not described
in sufficient detail, which means that uncertainty regarding the
methodological quality of trials remains. In particular, the identical
or closely similar number of patients in comparison groups in these
trials must be of concern.37 This could occur only if
blocked randomisation with a small block size had been used. Blocked or
stratified randomisation, however, was mentioned in only two
trials.
24 28
Conclusion
There is little evidence from these trials that keeping patients
nil by mouth is beneficial after elective gastrointestinal resection.
Although the data are clearly insufficient to conclude that early
feeding is of proved benefit, we believe that there is a good case for
an adequately powered clinical trial to assess early enteral feeding in
such patients. With anastomotic dehiscence as the primary end point,
such a trial would need to enrol about 1000 patients in each arm and
would therefore involve several centres.
| |
Acknowledgments |
|---|
We thank the authors who provided additional data: R Beier-Holgersen, B Stewart, S Wexner, J E Fischer, M F Brennan, and H Ortiz. We also thank the following manufacturers of enteral feeds for assisting in the collection of data: Nutricia, Fresenius Kabi, Novartis Nutrition UK, Ross Products, Clintec Nutrition, Nestlé (Clinical Nutrition), SHS International, Mead Johnson Nutrition.
Contributors: The data were extracted independently by SJL and PAS and checked for consistency by ST. ST and ME assessed the two dimensions of methodological quality. SJL wrote to all the trialists and feed companies requesting additional data and coordinated the writing of the paper. ME advised on the literature search and performed quality assessments and statistical analyses. All the authors contributed to the writing of the final draft of the manuscript. SJL is guarantor for the paper.
| |
Footnotes |
|---|
Funding: None.
Competing interests: None declared.
| |
References |
|---|
|
|
|---|
| 1. | Catchpole BN. Smooth muscle and the surgeon. Aust N Z J Surg 1989; 59: 199-208[Medline]. |
| 2. |
Moss G.
Maintenance of gastrointestinal function after bowel surgery and immediate enteral full nutrition. II. Clinical experience, with objective demonstration of intestinal absorption and motility.
J Parenter Enteral Nutr
1981;
5:
215-220 |
| 3. | McCarter MD, Gomez ME, Daly JM. Early postoperative enteral feeding following major upper gastrointestinal surgery. J Gastrointest Surg 1996; 1: 278-285[CrossRef]. |
| 4. |
McWhirter JP, Pennington CR.
Incidence and recognition of malnutrition in hospital.
BMJ
1994;
308:
945-948 |
| 5. | Hill GL, Pickford I, Young GA, Schorah CJ, Blackett RL, Burkinshaw L, et al. Malnutrition in surgical patients: an unrecognised problem. Lancet 1977; i: 689-692. |
| 6. | Lennard-Jones JE. A positive approach to nutrition as a treatment. London: King's Fund Centre, 1992. |
| 7. | The Veterans Affairs Total Parenteral Nutrition Cooperative Study Group. Perioperative total parenteral nutrition in surgical patients. N Engl J Med 1991; 325: 525-522[Abstract]. |
| 8. | Uden P, Blomquist P, Jiborn H, Zederfeldt B. Impact of long-term relative bowel rest on conditions for colonic surgery. Am J Surg 1988; 156: 381-385[CrossRef][Medline]. |
| 9. | Irvin TT, Hunt TK. Effect of malnutrition on colonic healing. Ann Surg 1974; 180: 765-772[Medline]. |
| 10. | Ward MW, Danzi M, Lewin MR, Rennie MJ, Clark CG. The effects of subclinical malnutrition and refeeding on the healing of experimental colonic anastomoses. Br J Surg 1982; 69: 308-310[CrossRef][Medline]. |
| 11. | Goodlad RA, Al-Mukhtar MY, Ghatei MA, Bloom SR, Wright NA. Cell proliferation, plasma enteroglucagon and plasma gastrin levels in starved and refed rats. Virchows Arch B Cell Pathol Incl Mol Pathol 1983; 43: 55-62[Medline]. |
| 12. | Moss G, Greenstein A, Levy S, Bierenbaum A. Maintenance of GI function after bowel surgery and immediate enteral full nutrition. I. Doubling of canine colorectal anastomotic bursting pressure and intestinal wound mature collagen content. Clinical experience, with objective demonstration of intestinal absorption and motility. J Parenter Enteral Nutr 1980; 4: 535-538[Abstract]. |
| 13. |
Schroeder D, Gillanders L, Mahr K, Hill GL.
Effects of immediate postoperative enteral nutrition on body composition, muscle function, and wound healing.
J Parenter Enteral Nutr
1991;
15:
376-383 |
| 14. |
Moore FA, Moore EE, Jones TN, McCroskey BL, Peterson VM.
TEN versus TPN following major abdominal trauma reduced septic morbidity.
J Trauma
1989;
29:
916-922[Medline].
|
| 15. |
Windsor AC, Kanwar S, Li AG, Barnes E, Guthrie JA, Spark JI, et al.
Compared with parenteral nutrition, enteral feeding attenuates the acute phase response and improves disease severity in acute pancreatitis.
Gut
1998;
42:
431-435 |
| 16. |
Schulz KF, Chalmers I, Hayes RJ, Altman DG.
Empirical evidence of bias. Dimensions of methodological quality associated with estimates of treatment effects in controlled trials.
JAMA
1995;
273:
408-412 |
| 17. | Moher D, Pham B, Jones A, Cook DJ, Jadad AR, Moher M, et al. Does quality of reports of randomised trials affect estimates of intervention efficacy reported in meta-analyses? Lancet 1998; 352: 609-613[CrossRef][Medline]. |
| 18. | Deeks JJ, Altman DG, Bradburn MJ. Statistical methods for examining heterogeneity and combining results from several studies in meta-analysis. In: Egger M, Smith DG, Altman DG, eds. Systematic reviews in health care: meta-analysis in context. London: BMJ Publishing, 2001:285-312. |
| 19. |
Egger M, Davey Smith G, Schneider M, Minder C.
Bias in meta-analysis detected by a simple, graphical test.
BMJ
1997;
315:
629-634 |
| 20. | Sagar S, Harland P, Shields R. Early postoperative feeding with elemental diet. BMJ 1979; i: 293-295. |
| 21. | Binderow SR, Cohen SM, Wexner SD, Nogueras JJ. Must early postoperative oral intake be limited to laparoscopy? Dis Colon Rectum 1994; 37: 584-589[CrossRef][Medline]. |
| 22. | Reissman P, Teoh TA, Cohen SM, Weiss EG, Nogueras JJ, Wexner SD. Is early oral feeding safe after elective colorectal surgery? A prospective randomised trial. Ann Surg 1995; 222: 73-77[Medline]. |
| 23. |
Carr CS, Ling KD, Boulos P, Singer M.
Randomised trial of safety and efficacy of immediate postoperative enteral feeding in patients undergoing gastrointestinal resection.
BMJ
1996;
312:
869-871 |
| 24. |
Beier-Holgersen R, Boesby S.
Influence of postoperative enteral nutrition on postsurgical infections.
Gut
1996;
39:
833-835 |
| 25. | Ortiz H, Armendariz P, Yarnoz C. Is early postoperative feeding feasible in elective colon and rectal surgery? Int J Colorectal Dis 1996; 11: 119-121[CrossRef][Medline]. |
| 26. | Heslin MJ, Latkany L, Leung D, Brooks AD, Hochwald SN, Pisters PW, et al. A prospective, randomized trial of early enteral feeding after resection of upper gastrointestinal malignancy. Ann Surg 1997; 226: 567-680[CrossRef][Medline]. |
| 27. |
Hartsell PA, Frazee RC, Harrison JB, Smith RW.
Early postoperative feeding after elective colorectal surgery.
Arch Surg
1997;
132:
518-521 |
| 28. | Watters JM, Kirkpatrick SM, Norris SB, Shamji FM, Wells GA. Immediate postoperative enteral feeding results in impaired respiratory mechanics and decreased mobility. Ann Surg 1997; 226: 369-380[CrossRef][Medline]. |
| 29. | Stewart BT, Woods RJ, Collopy BT, Fink RJ, Mackay JR, Keck JO. Early feeding after elective open colorectal resections: a prospective randomized trial. Aust N Z J Surg 1998; 68: 125-128[Medline]. |
| 30. | Ryan Jr JA, Page CP, Babcock L. Early postoperative jejunal feeding of elemental diet in gastrointestinal surgery. Am Surg 1981; 47: 393-403[Medline]. |
| 31. | Hoover Jr HC, Ryan JA, Anderson EJ, Fischer JE. Nutritional benefits of immediate postoperative jejunal feeding of an elemental diet. Am J Surg 1980; 139: 153-159[CrossRef][Medline]. |
| 32. | Wheeler JM, Gilbert JM. Controlled intraoperative water testing of left-sided colorectal anastomoses: are ileostomies avoidable. Ann R Coll Surg Engl 1999; 81: 105-108[Medline]. |
| 33. | Irvin TT, Goligher JC. Aetiology of disruption of intestinal anastomoses. Br J Surg 1973; 60: 461-464[CrossRef][Medline]. |
| 34. | Thornton FJ, Barbul A. Healing in the gastrointestinal tract. Surg Clin North Am 1997; 77: 549-573[CrossRef][Medline]. |
| 35. | Delmi M, Rapin CH, Bengoa JM, Delmas PD, Vasey H, Bonjour JP. Dietary supplementation in elderly patients with fractured neck of the femur. Lancet 1990; 335: 1013-1016[CrossRef][Medline]. |
| 36. | Schilder JM, Hurteau JA, Look KY, Moore DH, Raff G, Stehman FB, et al. A prospective controlled trial of early postoperative oral intake following major abdominal gynecologic surgery. Gynecol Oncol 1997; 67: 235-240[CrossRef][Medline]. |
| 37. |
Schulz KF, Chalmers I, Grimes DA, Altman DG.
Assessing the quality of randomization from reports of controlled trials published in obstetrics and gynecology journals.
JAMA
1994;
272:
125-128 |
(Accepted 30 May 2001)
Read all Rapid Responses