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Managing residual gastric volumes: To return or discard?
AUSTRALIAN CRITICAL CARE
Booker KJ, Niedringhaus L, Eden B, Arnold JS. Comparison of two methods of managing gastric residual volumes from feeding tubes.
American Journal of Critical Care 2000; (5):318.324.
OBJECTIVE OF THE STUDY The purpose of the study was to investigate the effect of discarding or returning residual gastric volumes aspirated from enteral feeding tubes. The investigators aimed to establish if the intervention had any effect on body weight, serum electrolyte levels and the frequency of complication associated with tube feeding.
RESEARCH METHODS Study d e s i g n The study was a two group prospective experimental design. One group had all residual volumes discarded and the other group had all residual volumes returned.
Setting a n d subjects The study was conducted in the intensive care units of three American hospitals for a period of 22 months. A total of 35 patients were recruited for the study. Patients were eligible for inclusion if they were to receive enteral nutrition for a period anticipated to be greater than 48 hours. Patients were originally included only if they had naso-gastric feeding tubes. However, following a slow recruitment, the inclusion criteria was later expanded to include those patients with oro-gastric tubes.
PROCEDURE The institutional review boards at each participating hospital approved the study. Patient or guardian consent was obtained prior to commencing the study and all feeding tubes had radiological confirmation for gastric placement. Patients remained in the study for a period of 7 days, until feeding was ceased or until the patient was discharged from ICU. Study guidelines were established prior to commencement. These included: ceasing feeds if residual volumes were greater than 150mI; repeated checks to be undertaken at 30 minutes and again for two subsequent checks if residual volumes remained high, then notify the physician; the bed head to be elevated above 30 degrees; and feeds to be stopped if the patient was to lay flat for procedures. Nurses were also to check pulmonary aspirates for glucose, monitor fluid balance and weight and record complications such as tube displacement, blockage, diarrhoea, nausea and vomiting. Serum electrolytes were also tested on commencement and on days 3 and 7.
RESULTS A total of 18 patients remained in the study for 3 days (discard group, n=10; return group, n=8). Only 11 patients remained in the study
VOLUME 14
for the total 7 days. Patient diagnoses varied and 72 per cent were intubated. The subgroups did not differ significantly across groups except for fluid balance; t (16)=2.25, p=0.04. Whilst no significant differences were found in weight or serum electrolytes, potassium levels did decrease in the discard group and increase in the return group, although neither were out of normal range. There were no significant changes across time between the discard and return groups. Complications consisted of tube replacements due to tube clogging in the return group, feeding delays due to high residuals or procedures, suspected pulmonary aspiration and diarrhoea and nausea. The discard group had 23.4 per cent complications compared with the 32.6 per cent for the return group.
AUTHORS' CONCLUSIONS While no significant differences were identified between the two groups in this study, the authors argued that the limited sample size could not exclude the possibility of significant differences in a larger sample. They proposed that the higher frequency of tube clogging in the return group, tube replacement and then radiological confirmation, suggests that discarding residual volumes may be indicated. However, the decrease in potassium for the discard group may also lead to further complications. Overall, the authors supported the discard of residual volumes as it was suggestive of lower complication rates, but cautioned a change in practice until the effectiveness could be rigorously tested in a larger sample size.
CRITIQUE Despite research supporting the physiological benefits of optimising nutritional status and decreasing adverse events in enteral feeding, most nursing interventions in this area have rarely been tested for effectiveness. This small study draws attention to a neglected area of critical care nursing research that has significant consequences for patient outcomes and should highlight the lack of evidence to support many of our traditional nursing practices. Overall, the study was well described and lacked only some minor details around issues such as the frequency of residual volume checks and the duration of feed cessation prior to laying the patient flat and conducting procedures. Despite the authors not commenting on the type or width of the tube, it was assumed that they were wide bore and readily aspirated. The study appeared to be well conducted and met the appropriate ethical standards. The limitations were clearly identified by the authors; the most significant being the small sample size that reduced
NUMBER 2
MAY 2001
AUSTRALIAN CRITICALCARE
the likelihood of establishing a significant effect. Despite this substantial limitation, the authors correctly asserted that the study raises our awareness of the many issues surrounding enteral feeding.
The study also provided limited discussion on other variables that may impact on the complication rate. For example, the type and frequency of medications being flushed down the enteral tube is a clinically important variable known to lead to tube blockage. There was no indication that this variable was examined in this study. In fact, the authors inferred that returning residual volumes were the only reason for blockage.
A further limitation of the study was the extended duration of the data collection and the low recruitment rate over 22 months. The authors did not describe the frequency of nurse education sessions which are important in promoting comp[iance with study guidelines and protocol. Furthermore, retrospective data collection from medical histories has been repeatedly shown in research to threaten internal validity through gaps in the documentation. In this case, the expanded duration of data collection and the slow recruitment may have exacerbated normal compliance problems.
Nevertheless, this article is particularly useful in highlighting the lack of research in supporting a global nursing intervention. It clearly illustrates the design weaknesses to be addressed in future research into enteral feeding and the management of residual gastric contents.
Tracey Bucknall Executive Director, Victorian Centre for Nursing Practice Research School of Postgraduate Nursing Faculty of Medicine, Dentistry and Health Sciences The University of Melbourne •
The authors also noted that some outcomes measures were not collected, yet potentially may have impacted on the results, such as the relationship between fluid balance and serum electrolytes. In addition, attempts to control for the contextual variables known to impact on the data measured were possibly hampered by the number of locations required for recruitment.
nor is it a membership renewal form. J i r i e s and for membership forms.
Australian Critical Care Nurses Inc. JOURNAL S U B S C R I P T I O N F O R M ~
individual(Australia):
$A66.00 includes GST
~
Individual (Overseas, by airmail): $A75.00
~
Institution(Australia):
$A88.00 includesGST
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Institution(Overseas,by airmail): SA100.00
Enclosed is annual subscription payment. Cheque or money order made payable to Australian Critical Care or charge to: ~Bankcard ~MasterCard ~ V i s a Card N o . ~
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Please marl journals to (print all information) Name Institution Delivery address State Telephone (
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Please post form to: Australian Critical Care Subscriptions, c/o Cambridge Media
17 Northwood Street, West Leederville, WA 6007, Australia
VOLUME 14 NUMBER2 MAY 2001
Postcode Facsimile (
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~
Booker KJ, Niedringhaus L, Eden B, Arnold JS. Comparison of two methods of managing gastric residual volumes from feeding tubes.
American Journal of Critical Care 2000; (5):318.324.
OBJECTIVE OF THE STUDY The purpose of the study was to investigate the effect of discarding or returning residual gastric volumes aspirated from enteral feeding tubes. The investigators aimed to establish if the intervention had any effect on body weight, serum electrolyte levels and the frequency of complication associated with tube feeding.
RESEARCH METHODS Study d e s i g n The study was a two group prospective experimental design. One group had all residual volumes discarded and the other group had all residual volumes returned.
Setting a n d subjects The study was conducted in the intensive care units of three American hospitals for a period of 22 months. A total of 35 patients were recruited for the study. Patients were eligible for inclusion if they were to receive enteral nutrition for a period anticipated to be greater than 48 hours. Patients were originally included only if they had naso-gastric feeding tubes. However, following a slow recruitment, the inclusion criteria was later expanded to include those patients with oro-gastric tubes.
PROCEDURE The institutional review boards at each participating hospital approved the study. Patient or guardian consent was obtained prior to commencing the study and all feeding tubes had radiological confirmation for gastric placement. Patients remained in the study for a period of 7 days, until feeding was ceased or until the patient was discharged from ICU. Study guidelines were established prior to commencement. These included: ceasing feeds if residual volumes were greater than 150mI; repeated checks to be undertaken at 30 minutes and again for two subsequent checks if residual volumes remained high, then notify the physician; the bed head to be elevated above 30 degrees; and feeds to be stopped if the patient was to lay flat for procedures. Nurses were also to check pulmonary aspirates for glucose, monitor fluid balance and weight and record complications such as tube displacement, blockage, diarrhoea, nausea and vomiting. Serum electrolytes were also tested on commencement and on days 3 and 7.
RESULTS A total of 18 patients remained in the study for 3 days (discard group, n=10; return group, n=8). Only 11 patients remained in the study
VOLUME 14
for the total 7 days. Patient diagnoses varied and 72 per cent were intubated. The subgroups did not differ significantly across groups except for fluid balance; t (16)=2.25, p=0.04. Whilst no significant differences were found in weight or serum electrolytes, potassium levels did decrease in the discard group and increase in the return group, although neither were out of normal range. There were no significant changes across time between the discard and return groups. Complications consisted of tube replacements due to tube clogging in the return group, feeding delays due to high residuals or procedures, suspected pulmonary aspiration and diarrhoea and nausea. The discard group had 23.4 per cent complications compared with the 32.6 per cent for the return group.
AUTHORS' CONCLUSIONS While no significant differences were identified between the two groups in this study, the authors argued that the limited sample size could not exclude the possibility of significant differences in a larger sample. They proposed that the higher frequency of tube clogging in the return group, tube replacement and then radiological confirmation, suggests that discarding residual volumes may be indicated. However, the decrease in potassium for the discard group may also lead to further complications. Overall, the authors supported the discard of residual volumes as it was suggestive of lower complication rates, but cautioned a change in practice until the effectiveness could be rigorously tested in a larger sample size.
CRITIQUE Despite research supporting the physiological benefits of optimising nutritional status and decreasing adverse events in enteral feeding, most nursing interventions in this area have rarely been tested for effectiveness. This small study draws attention to a neglected area of critical care nursing research that has significant consequences for patient outcomes and should highlight the lack of evidence to support many of our traditional nursing practices. Overall, the study was well described and lacked only some minor details around issues such as the frequency of residual volume checks and the duration of feed cessation prior to laying the patient flat and conducting procedures. Despite the authors not commenting on the type or width of the tube, it was assumed that they were wide bore and readily aspirated. The study appeared to be well conducted and met the appropriate ethical standards. The limitations were clearly identified by the authors; the most significant being the small sample size that reduced
NUMBER 2
MAY 2001
AUSTRALIAN CRITICALCARE
the likelihood of establishing a significant effect. Despite this substantial limitation, the authors correctly asserted that the study raises our awareness of the many issues surrounding enteral feeding.
The study also provided limited discussion on other variables that may impact on the complication rate. For example, the type and frequency of medications being flushed down the enteral tube is a clinically important variable known to lead to tube blockage. There was no indication that this variable was examined in this study. In fact, the authors inferred that returning residual volumes were the only reason for blockage.
A further limitation of the study was the extended duration of the data collection and the low recruitment rate over 22 months. The authors did not describe the frequency of nurse education sessions which are important in promoting comp[iance with study guidelines and protocol. Furthermore, retrospective data collection from medical histories has been repeatedly shown in research to threaten internal validity through gaps in the documentation. In this case, the expanded duration of data collection and the slow recruitment may have exacerbated normal compliance problems.
Nevertheless, this article is particularly useful in highlighting the lack of research in supporting a global nursing intervention. It clearly illustrates the design weaknesses to be addressed in future research into enteral feeding and the management of residual gastric contents.
Tracey Bucknall Executive Director, Victorian Centre for Nursing Practice Research School of Postgraduate Nursing Faculty of Medicine, Dentistry and Health Sciences The University of Melbourne •
The authors also noted that some outcomes measures were not collected, yet potentially may have impacted on the results, such as the relationship between fluid balance and serum electrolytes. In addition, attempts to control for the contextual variables known to impact on the data measured were possibly hampered by the number of locations required for recruitment.
nor is it a membership renewal form. J i r i e s and for membership forms.
Australian Critical Care Nurses Inc. JOURNAL S U B S C R I P T I O N F O R M ~
individual(Australia):
$A66.00 includes GST
~
Individual (Overseas, by airmail): $A75.00
~
Institution(Australia):
$A88.00 includesGST
~
Institution(Overseas,by airmail): SA100.00
Enclosed is annual subscription payment. Cheque or money order made payable to Australian Critical Care or charge to: ~Bankcard ~MasterCard ~ V i s a Card N o . ~
~
~
~
~
~
Signature
Expires ~
Please marl journals to (print all information) Name Institution Delivery address State Telephone (
)
Postcode Facsimile (
)
Invoice address (if applicable) State Telephone (
)
Please post form to: Australian Critical Care Subscriptions, c/o Cambridge Media
17 Northwood Street, West Leederville, WA 6007, Australia
VOLUME 14 NUMBER2 MAY 2001
Postcode Facsimile (
)
/
~