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Should gastric aspirate be discarded or retained when gastric residual volume is removed from gastric tubes?
Australian Critical Care (2010) 23, 215—217
RESEARCH REVIEW
Should gastric aspirate be discarded or retained when gastric residual volume is removed from gastric tubes? Teresa A. Williams (RN, PhD, MHlthSci(Res), PG Dip Clin Epi, BN, ICU Cert) a,b,∗, Gavin D. Leslie (RN, PhD, BAppSc, PG Dip, ICU Cert) a,b,1 a b
Critical Care Division, Royal Perth Hospital, Perth, Western Australia, 6000, Australia School of Nursing, Midwifery, Curtin Health Innovation Research Institute, Curtin University, Australia
Received 27 April 2010 ; received in revised form 7 May 2010; accepted 10 May 2010
Maria-Eulàlia Juvé-Udina, Consol Valls-Miró, Avelina Carre˜ no-Granero, Gemma Martinez-Estalella, David Monterde-Prat, Carmen-Maria Domingo-Felici, Joan Llusa-Finestres, Gemma Asensio-Malo. To return or to discard? Randomised trial on gastric residual volume management. Intensive and Critical Care Nursing 2009;25:258—267. KEYWORDS Intensive care; Enteral feeding; Randomised control trial
Summary Nursing care of patients with enteral feeding tubes is common in the intensive care unit but the evidence that surrounds the practice is limited. Recent research by Juve-Udina and colleagues (2010) ‘‘To return or to discard? Randomised trial on gastric residual volume management’’ compares two methods of managing gastric residual volume. This critique provides a brief summary of their research and critically appraises the paper. The implications for nursing practice are discussed. © 2010 Australian College of Critical Care Nurses Ltd. Published by Elsevier Australia (a division of Reed International Books Australia Pty Ltd). All rights reserved.
∗ Corresponding author. Tel.: +61 439 907 616; fax: +61 8 9224 3668. E-mail addresses: [email protected] (T.A. Williams), [email protected] (G.D. Leslie). 1 Tel.: +61 404103344; fax: +61 8 9224 2255.
Objectives: This study1 aimed to determine the effect of returning or discarding the gastric residual volume (GRV) on gastric emptying delays and feeding, electrolyte balance and patient outcomes among critically ill patients. Gastric emptying delay (GED) was defined as the difficulty in maintain-
1036-7314/ $ — see front matter © 2010 Australian College of Critical Care Nurses Ltd. Published by Elsevier Australia (a division of Reed International Books Australia Pty Ltd). All rights reserved.
doi:10.1016/j.aucc.2010.05.001
216 ing GRV within safe limits, i.e. below 5 ml/kg. The GED was categorised as light GED (151—250 ml/6 h), moderate GED (251—350 ml/6 h) or severe GED (>350 ml/6 h). Methods: The prospective, randomised clinical trial was conducted in a single medical—surgical intensive care unit (ICU) of a public university hospital. Patients admitted to the ICU for longer than 48 h, aged 18 or older, who had haemodynamic monitoring and were fed enterally or parenterally were recruited to the study over one year. Participants were excluded if connected to an intermittent gastric aspiration system. Computer-generated randomisation was used to randomise participants to the return (intervention) or discard (control) group. The estimated sample size (59 participants in each group) was informed by sample size calculations. The study finished for a participant if: (1) there was no need for further GRV monitoring, (2) occurrence of adverse event associated with the procedure (pulmonary aspiration or cardio-respiratory arrest during or immediately after the procedure), (3) faecal aspirates, (4) major protocol error or (5) death. Gastric residual volumes were checked every 6 h and an algorithm was used to guide management of GRV. Data were collected by the investigators or by the trained registered nurses from the ICU and included the incidence of (1) blocked NGT; (2) pulmonary aspiration episodes; (3) intolerance episodes (nausea, vomiting, diarrhoea and abdominal distension); (4) enteral feeding delays; (5) hyperkalaemia episodes; (6) hyperglycaemia episodes and (7) discomfort episodes, identified by significant changes in vital signs and also from the Ramsay sedation score.2 Results and conclusion: No significant differences were found in participant demographics or outcome measures between the groups. The exceptions were participants in the intervention group had a lower incidence and severity of delayed gastric emptying episodes (p = 0.001) and more episodes of hyperglycaemia. The investigators concluded that returning gastric aspirates improved GRV management without increasing the risk for potential complications.
Critique Gastric residual volume (GRV) is routinely measured in Australian ICU to monitor gastric tolerance to enteral feeding and abdominal decompression and drainage for patients not fed enterally. This study compared two methods of managing gastric aspirate after it was removed from the stomach, i.e. return or discard. Gastric aspirates were returned
T.A. Williams, G.D. Leslie in the ‘intervention’ group if the GRV was not greater than 250 ml, if so then the return volume was limited to 250 ml. While using a robust study design in an area of relevance to critical care nursing there are omissions and discrepancies in both the conduct of the study and analysis which undermine the credibility of the findings. The value for maintaining GRV within safe limits, i.e. below 5 ml/kg was cited by Horn et al.3 in their secondary analysis of intermittent versus continuous feeding in a paediatric ICU. Horn et al.3 used the value recommended by Taylor and Baker4 (the primary reference) in their paper published on paediatric enteral nutrition. There was no information on how this value was derived and it may not be appropriate for adults. The GED was categorised into 3 groups but the rationale for using these categories was not provided. Other important outcomes of interest are not well defined. For example testing glucose values in pulmonary secretions is not an acceptable method to define pulmonary aspiration. The report does not explicitly define the ‘discard’ group. In conducting the study, randomisation procedures are explained but it is unclear who controlled allocation of patients to the return or discard group, thereby opening the study to selection bias if the allocation was inconsistent. The study is unblinded as expected but mention of why it was not possible to blind should be included in the report. All patients were accounted for but ‘‘intention to treat’’ principles were not used. The type of ICU, but not its location, is reported as mixed medicalsurgical (general) ICU which are the most common ICUs in Australia. The selection criteria were listed and recruitment was described as continuous over a year. It is revealed later in the paper that recruitment did not occur for 2 months over summer although no reason for not recruiting during this period was provided. This may have been an important omission as outlined in the authors’ discussion. An algorithm was used to guide management of GRV but it is unclear and two standard volumes were prescribed for enteral feeds. While feeding was administered continuously the algorithm indicates different administration and cessation times which are quite confusing. The data collected on factors that may be potentially affected by the return or discard of GRV were impressive. The lack of significance between groups is disappointing but not unexpected. Even though sample size calculations were performed, the estimates for the effect size may not be realistic and subgroup analysis was not decided a priori. While the limitations of the study were discussed important issues such as conduct of the
Should gastric aspirate be discarded or retained? study in a single centre, use of subgroup analyses and not using intention to treat analysis were omitted. A major limitation in our opinion was to include patients who received parenteral nutrition. It would be more informative to study only those patients receiving enteral feeding in a sufficiently large sample using a strict standardised feeding regimen to assess the effect of administering enteral nutrition and the effect of GED. Patients who receive parenteral nutrition are likely to have impaired gut function and their inclusion only confuses the results. Performing some statistical modelling may have enhanced understanding of the outcomes of the study. There is a wide variation in the management of GRV and little available evidence to guide practice.5 The volume of GRV considered excessive and the ideal frequency of checking GRV have not been established. Similarly, whether to return or discard gastric aspirate is controversial. The argument to support return of aspirates to maintain electrolyte and fluid balance was not shown in this study. Discarding aspirates minimises handling of
217 feed delivery systems and risk of contamination but exposes staff to splash injury; these events were not measured. While this study provides some information about GED high quality research is needed to answer some of these difficult questions. There is not enough evidence from this study to guide or change practice.
References 1. Juvé-Udina M-E, Valls-Miró C, Carreno-Granero A, MartinezEstalella G, Monterde-Prat D, Domingo-Felici C-M, et al. To return or to discard? Randomised trial on gastric residual volume management. Intensive Crit Care Nurs 2009;25:258—67. 2. Ramsay MA, Savege TM, Simpson BR, Goodwin R. Controlled sedation with alphaxalone-alphadolone. BMJ 1974;2:656—9. 3. Horn D, Chaboyer W, Schluter PJ. Gastric residual volumes in critically ill paediatric patients: a comparison of feeding regimens. Aust Crit Care 2004;17:98—100. 4. Taylor R, Baker A. Enteral nutrition in critical illness: part one. Paediatr Nurs 1999;11:16—20. 5. Williams TA, Leslie GD. A review of the nursing care of enteral feeding tubes in critically ill adults: part II. Intensive Crit Care Nurs 2005;21:5—15.
Available online at www.sciencedirect.com
RESEARCH REVIEW
Should gastric aspirate be discarded or retained when gastric residual volume is removed from gastric tubes? Teresa A. Williams (RN, PhD, MHlthSci(Res), PG Dip Clin Epi, BN, ICU Cert) a,b,∗, Gavin D. Leslie (RN, PhD, BAppSc, PG Dip, ICU Cert) a,b,1 a b
Critical Care Division, Royal Perth Hospital, Perth, Western Australia, 6000, Australia School of Nursing, Midwifery, Curtin Health Innovation Research Institute, Curtin University, Australia
Received 27 April 2010 ; received in revised form 7 May 2010; accepted 10 May 2010
Maria-Eulàlia Juvé-Udina, Consol Valls-Miró, Avelina Carre˜ no-Granero, Gemma Martinez-Estalella, David Monterde-Prat, Carmen-Maria Domingo-Felici, Joan Llusa-Finestres, Gemma Asensio-Malo. To return or to discard? Randomised trial on gastric residual volume management. Intensive and Critical Care Nursing 2009;25:258—267. KEYWORDS Intensive care; Enteral feeding; Randomised control trial
Summary Nursing care of patients with enteral feeding tubes is common in the intensive care unit but the evidence that surrounds the practice is limited. Recent research by Juve-Udina and colleagues (2010) ‘‘To return or to discard? Randomised trial on gastric residual volume management’’ compares two methods of managing gastric residual volume. This critique provides a brief summary of their research and critically appraises the paper. The implications for nursing practice are discussed. © 2010 Australian College of Critical Care Nurses Ltd. Published by Elsevier Australia (a division of Reed International Books Australia Pty Ltd). All rights reserved.
∗ Corresponding author. Tel.: +61 439 907 616; fax: +61 8 9224 3668. E-mail addresses: [email protected] (T.A. Williams), [email protected] (G.D. Leslie). 1 Tel.: +61 404103344; fax: +61 8 9224 2255.
Objectives: This study1 aimed to determine the effect of returning or discarding the gastric residual volume (GRV) on gastric emptying delays and feeding, electrolyte balance and patient outcomes among critically ill patients. Gastric emptying delay (GED) was defined as the difficulty in maintain-
1036-7314/ $ — see front matter © 2010 Australian College of Critical Care Nurses Ltd. Published by Elsevier Australia (a division of Reed International Books Australia Pty Ltd). All rights reserved.
doi:10.1016/j.aucc.2010.05.001
216 ing GRV within safe limits, i.e. below 5 ml/kg. The GED was categorised as light GED (151—250 ml/6 h), moderate GED (251—350 ml/6 h) or severe GED (>350 ml/6 h). Methods: The prospective, randomised clinical trial was conducted in a single medical—surgical intensive care unit (ICU) of a public university hospital. Patients admitted to the ICU for longer than 48 h, aged 18 or older, who had haemodynamic monitoring and were fed enterally or parenterally were recruited to the study over one year. Participants were excluded if connected to an intermittent gastric aspiration system. Computer-generated randomisation was used to randomise participants to the return (intervention) or discard (control) group. The estimated sample size (59 participants in each group) was informed by sample size calculations. The study finished for a participant if: (1) there was no need for further GRV monitoring, (2) occurrence of adverse event associated with the procedure (pulmonary aspiration or cardio-respiratory arrest during or immediately after the procedure), (3) faecal aspirates, (4) major protocol error or (5) death. Gastric residual volumes were checked every 6 h and an algorithm was used to guide management of GRV. Data were collected by the investigators or by the trained registered nurses from the ICU and included the incidence of (1) blocked NGT; (2) pulmonary aspiration episodes; (3) intolerance episodes (nausea, vomiting, diarrhoea and abdominal distension); (4) enteral feeding delays; (5) hyperkalaemia episodes; (6) hyperglycaemia episodes and (7) discomfort episodes, identified by significant changes in vital signs and also from the Ramsay sedation score.2 Results and conclusion: No significant differences were found in participant demographics or outcome measures between the groups. The exceptions were participants in the intervention group had a lower incidence and severity of delayed gastric emptying episodes (p = 0.001) and more episodes of hyperglycaemia. The investigators concluded that returning gastric aspirates improved GRV management without increasing the risk for potential complications.
Critique Gastric residual volume (GRV) is routinely measured in Australian ICU to monitor gastric tolerance to enteral feeding and abdominal decompression and drainage for patients not fed enterally. This study compared two methods of managing gastric aspirate after it was removed from the stomach, i.e. return or discard. Gastric aspirates were returned
T.A. Williams, G.D. Leslie in the ‘intervention’ group if the GRV was not greater than 250 ml, if so then the return volume was limited to 250 ml. While using a robust study design in an area of relevance to critical care nursing there are omissions and discrepancies in both the conduct of the study and analysis which undermine the credibility of the findings. The value for maintaining GRV within safe limits, i.e. below 5 ml/kg was cited by Horn et al.3 in their secondary analysis of intermittent versus continuous feeding in a paediatric ICU. Horn et al.3 used the value recommended by Taylor and Baker4 (the primary reference) in their paper published on paediatric enteral nutrition. There was no information on how this value was derived and it may not be appropriate for adults. The GED was categorised into 3 groups but the rationale for using these categories was not provided. Other important outcomes of interest are not well defined. For example testing glucose values in pulmonary secretions is not an acceptable method to define pulmonary aspiration. The report does not explicitly define the ‘discard’ group. In conducting the study, randomisation procedures are explained but it is unclear who controlled allocation of patients to the return or discard group, thereby opening the study to selection bias if the allocation was inconsistent. The study is unblinded as expected but mention of why it was not possible to blind should be included in the report. All patients were accounted for but ‘‘intention to treat’’ principles were not used. The type of ICU, but not its location, is reported as mixed medicalsurgical (general) ICU which are the most common ICUs in Australia. The selection criteria were listed and recruitment was described as continuous over a year. It is revealed later in the paper that recruitment did not occur for 2 months over summer although no reason for not recruiting during this period was provided. This may have been an important omission as outlined in the authors’ discussion. An algorithm was used to guide management of GRV but it is unclear and two standard volumes were prescribed for enteral feeds. While feeding was administered continuously the algorithm indicates different administration and cessation times which are quite confusing. The data collected on factors that may be potentially affected by the return or discard of GRV were impressive. The lack of significance between groups is disappointing but not unexpected. Even though sample size calculations were performed, the estimates for the effect size may not be realistic and subgroup analysis was not decided a priori. While the limitations of the study were discussed important issues such as conduct of the
Should gastric aspirate be discarded or retained? study in a single centre, use of subgroup analyses and not using intention to treat analysis were omitted. A major limitation in our opinion was to include patients who received parenteral nutrition. It would be more informative to study only those patients receiving enteral feeding in a sufficiently large sample using a strict standardised feeding regimen to assess the effect of administering enteral nutrition and the effect of GED. Patients who receive parenteral nutrition are likely to have impaired gut function and their inclusion only confuses the results. Performing some statistical modelling may have enhanced understanding of the outcomes of the study. There is a wide variation in the management of GRV and little available evidence to guide practice.5 The volume of GRV considered excessive and the ideal frequency of checking GRV have not been established. Similarly, whether to return or discard gastric aspirate is controversial. The argument to support return of aspirates to maintain electrolyte and fluid balance was not shown in this study. Discarding aspirates minimises handling of
217 feed delivery systems and risk of contamination but exposes staff to splash injury; these events were not measured. While this study provides some information about GED high quality research is needed to answer some of these difficult questions. There is not enough evidence from this study to guide or change practice.
References 1. Juvé-Udina M-E, Valls-Miró C, Carreno-Granero A, MartinezEstalella G, Monterde-Prat D, Domingo-Felici C-M, et al. To return or to discard? Randomised trial on gastric residual volume management. Intensive Crit Care Nurs 2009;25:258—67. 2. Ramsay MA, Savege TM, Simpson BR, Goodwin R. Controlled sedation with alphaxalone-alphadolone. BMJ 1974;2:656—9. 3. Horn D, Chaboyer W, Schluter PJ. Gastric residual volumes in critically ill paediatric patients: a comparison of feeding regimens. Aust Crit Care 2004;17:98—100. 4. Taylor R, Baker A. Enteral nutrition in critical illness: part one. Paediatr Nurs 1999;11:16—20. 5. Williams TA, Leslie GD. A review of the nursing care of enteral feeding tubes in critically ill adults: part II. Intensive Crit Care Nurs 2005;21:5—15.
Available online at www.sciencedirect.com