Conservative interventions for the management of impacted food bolus in the oesophagus
Abstract
This is a protocol for a Cochrane Review (Intervention). The objectives are as follows:
To evaluate the efficacy of non‐procedural interventions in the management of soft food boluses impacted within the oesophagus.
Background
Description of the condition
The oesophagus is a muscular tube that acts as a conduit between the throat and stomach. It begins at the end of the pharynx, travels through the neck and thorax, and finishes in the abdomen at the stomach. The oesophagus is between 18 cm to 25 cm in length and comprises skeletal muscle proximally, smooth muscle distally, and a mixture in its central portion (Gatzoulis 2009). Boluses of swallowed food are moved along this muscular tube by coordinated waves of contractility, called peristalsis. Food or other material may become ‘impacted’ in the oesophagus and result in partial or total oesophageal obstruction. In the community most of these impactions resolve spontaneously and are never presented to healthcare professionals (Liu 2012). The remainder may present acutely to hospital emergency departments, and subsequently ear, nose, and throat (ENT) surgeons or gastroenterologists, and may ultimately require some form of procedural intervention to disimpact the obstruction (Larsson 2011).
Notably, non‐organic oesophageal foreign bodies, or organic food boluses that have hard or sharp components (e.g. bone), pose a significant risk of perforating the oesophageal wall (Barabino 2015; Mezzetto 2016; Park 2016). As such, they are managed differently as they require immediate removal via rigid or flexible oesophagoscopy. Soft food bolus impaction of the oesophagus may undergo an initial period of non‐procedural management and these soft bolus impactions will form the focus of this Cochrane Review.
People with a persistent oesophageal soft food bolus impaction are at risk of further morbidity. The inability to swallow effectively can cause significant distress and discomfort. Furthermore, these people can become rapidly dehydrated as the usual upper aerodigestive secretions are not resorbed and no further oral nutritional intake is possible. Additionally, they risk aspiration into the tracheobronchial system: either from matter passing directly into the larynx as it is unable to enter the proximal oesophagus, or from food material in the proximal oesophagus, above the impaction, being regurgitated into the larynx. In time, if the impaction does not dislodge, the adjacent oesophageal mucosa will become oedematous and inflamed, risking ischaemia, perforation, and ultimately leading to mediastinitis (Liu 2012). If not appreciated and treated promptly this carries a mortality approaching 100% (Bladergroen 1986). There is therefore a need to disimpact these soft food boluses to prevent potentially serious complications.
Many strategies have been described to resolve soft food bolus impactions. These include watchful waiting, administration of topical and systemic agents, and physical removal or dislodgement (Nandi 1978; Anderson 2007; Marano 2016; Morse 2016). A large number of boluses pass without procedural intervention. Those that do not clear will commonly undergo endoscopic disimpaction with either a rigid or flexible oesophagoscope, whilst others may be instrumented blindly, for example with nasogastric tubes (Marano 2016). Oesophagoscopy is considered the definitive management strategy for persistent cases, though many advocate a period of more conservative management in the first instance due to the potential complications associated with the procedural intervention (Wennervaldt 2012). It is these non‐procedural interventions that we will investigate in this review.
Description of the intervention
We have divided the non‐procedural interventions for soft food boluses impacted in the oesophagus into pharmacological and non‐pharmacological agents.
Pharmacological agents are defined as biologically active substances that have their effect on the tissue of the oesophagus itself. These agents are most commonly administered via a parenteral route, owing to the presence of the impaction in the proximal alimentary canal. Commonly used pharmacological agents and the mechanism of action are: hyoscine butylbromide; glucagon; calcium channel blockers; and benzodiazepines.
Non‐pharmacological agents such as gas forming‐agents, carbonated drinks, and pineapple juice are taken orally and have their effect on the bolus itself, rather than the surrounding tissues.
For many studies reporting on soft food bolus impaction, the comparator group to the intervention is a period of watchful waiting. In addition to watchful waiting, many non‐procedural interventions have been employed to disimpact soft food boluses. For the purposes of this review, we have divided these interventions into pharmacological and non‐pharmacological agents.
How the intervention might work
Pharmacological
Pharmacological agents all aim to relax the muscular contractions within the oesophagus, thereby allowing the impacted food bolus to continue its passage through the oesophagus to the stomach. Depending on the level of impaction within the oesophagus, these agents may target smooth muscle or skeletal muscle.
Hyoscine butylbromide is an anticholinergic agent which inhibits parasympathetic action on smooth muscle resulting in relaxation and dilatation. It may be given subcutaneously, intramuscularly, or intravenously and is most commonly administered four times daily (Tytgat 2007). There are no serious side effects commonly encountered with Hyoscine butylbromide.
Glucagon is a single chain polypeptide hormone which works to raise serum glucose level and also relax smooth muscle in the lower oesophageal sphincter and distal oesophagus. It may be given subcutaneously, intramuscularly or intravenously (Colon 1999). Side effects include hyperglycaemia and caution should be exercised in use with diabetic patients.
Calcium channel blockers inhibit the entry of calcium ions into smooth muscle cells, reducing their ability to contract and so allowing dilatation (Katz 1986). They are used primarily in cardiovascular disease and so common potentially serious side effects include arrhythmias and hypotension. They must be used with caution alongside other cardiovascular drugs.
Benzodiazepines increase the effects of gamma amino butyric acid (GABA) at the GABA‐A receptor, reducing the excitability of neurons. Amongst other effects, this can result in relaxation of skeletal muscle found in the proximal oesophagus. They must be used cautiously due to their potentially serious side effect of central respiratory depression (Griffin 2013).
Non‐pharmacological
Gas‐forming agents, such as carbonated drinks, are thought to create increased pressure between the obstruction and cricopharyngeal sphincter above, physically dislodging the impacted food bolus inferiorly.
Pineapple juice contains the proteolytic 'bromelain' which aims to dissolve the food bolus through enzymatic process. The practice of enzymatic disimpaction has largely ceased because of the non‐selective nature of the digestive agents, affecting not only the foreign body but also the oesophageal wall, with the inherent risk of subsequent perforation (Morse 2016).
Watchful waiting aims to allow more time for the bolus to pass spontaneously.The muscle fibres surrounding the bolus, which may be in spasm, may have more time to relax of their own accord allowing the bolus to pass into the stomach. Watchful waiting aims to avoid the need for any intervention and the potential for any associated side effects or complications.
Why it is important to do this review
Timely management of oesophageal food bolus impaction is essential to prevent life‐threatening complications, as outlined previously. Prevailing clinical consensus suggests that non‐procedural methods should be trialled initially to help minimise the exposure to risk from procedural interventions. However, there is no robust evidence as to which non‐procedural strategies should be employed, and for how long, before procedural intervention is considered. Endoscopic interventions have the potential to bring about faster resolution of the impaction, but also present potential risks and complications. If non‐procedural strategies are shown to be effective, then a large number of people may avoid these potential complications.
Objectives
To evaluate the efficacy of non‐procedural interventions in the management of soft food boluses impacted within the oesophagus.
Methods
Criteria for considering studies for this review
Types of studies
We will include randomised controlled studies that compare conservative (non‐procedural) interventions for impacted oesophageal food boluses against other agents, placebo, or watchful waiting.
Types of participants
Inclusion criteria
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People of any age.
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History of acute soft food bolus ingestion.
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History suggestive of oesophageal impaction. This may manifest as complete aphagia, suggesting a proximal blockage, or with delayed regurgitation, which is more suggestive of a distal oesophageal impaction.
Exclusion criteria
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History of sharp or solid object ingestion whether food derived, such as animal bone, or ‘foreign’, such as dentures or coins.
Types of interventions
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We will consider all non‐procedural interventions for inclusion. These are broadly divided into pharmacological or non‐pharmacological agents (including watchful waiting alone).
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Combinations of treatments will also be eligible, provided the initial management does not include direct instrumentation of the bolus.
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We will consider all doses and dosing regimens.
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We will consider all parenteral routes, where applicable.
Types of outcome measures
Primary outcomes
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Incidence of return to oral diet without need for procedural intervention.
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Serious adverse events (to include aspiration, perforation, and death).
Secondary outcomes
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Adverse events (to include side effects to pharmacological and non‐pharmacological interventions and damage to teeth, lips, or gums from procedural interventions).
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Duration of impaction before return to oral diet without need for procedural intervention.
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Patient satisfaction scores from interventions.
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Length of hospital stay.
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Re‐presentation with soft food bolus impaction.
Search methods for identification of studies
We will conduct systematic searches of the published and unpublished literature to identify randomised controlled studies relevant to our review question. There will be no restrictions related to year of publication, publication status, or the language of publication, and we will arrange translations as appropriate. Where we require data, we will attempt to seek clarifications from the study authors directly.
Electronic searches
We will search the following electronic databases for identifying potential studies.
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Cochrane Central Register of Controlled Trials (CENTRAL) (Appendix 1).
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MEDLINE (1966 to present) (Appendix 2).
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Embase (1988 to present) (Appendix 3).
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CINAHL (1982 to present).
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PubMed.
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ISI Web of Science.
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China National Knowledge Infrastructure (CNKI).
We will also conduct a search of ClinicalTrials.gov.
Searching other resources
We will check reference lists of all primary studies and review articles for additional references. We will contact authors of identified studies and ask them to identify other published and unpublished studies.
We will also contact manufacturers of agents used for the non‐endoscopic dislodgement of impacted oesophageal food boluses.
We will search for errata or retractions from eligible studies at www.ncbi.nlm.nih.gov/pubmed and we will record the date we searched in the review.
Data collection and analysis
Selection of studies
Two review authors (JH and NS) will independently screen titles and abstracts of studies identified by the above search strategy with potential for inclusion. They will code them as either 'retrieve' (eligible or potentially eligible/unclear) or 'do not retrieve'. For articles coded as 'retrieve', we will obtain the full‐text study reports/publication. Two review authors (JH and NS) will then independently assess the text to identify studies for inclusion. They will exclude ineligible studies and will record the reason for exclusion. We will resolve any disagreement through discussion or, if required, will consult a third review author (JS). We will identify and exclude duplicates and collate multiple reports of the same study, so that each study rather than each report is the unit of interest in the review. We will record the selection process in sufficient detail to complete a PRISMA flow diagram and a 'Characteristics of excluded studies' table.
Data extraction and management
We will use a standard data collection form for study characteristics and outcome data that has been piloted on at least one study included in the review. Two review authors (JH and NS) will extract study characteristics independently from included studies. We will extract the following study characteristics.
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Methods: study design, total duration study and run in, number of study centres and location, study setting, withdrawals, date of study.
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Participants: N, mean age, age range, gender, severity of condition, diagnostic criteria, baseline lung function, smoking history, inclusion criteria, exclusion criteria.
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Interventions: intervention, comparison, concomitant medications, excluded medications.
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Outcomes: primary and secondary outcomes specified and collected, time points reported.
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Notes: funding for study, notable conflicts of interest of study authors.
Two review authors (JH and NS) will independently extract outcome data from included studies. We will note in the 'Characteristics of included studies' table if the study authors reported data outcome data in an unusable way. We will resolve disagreements by consensus or by involving a third review author (JS). One review author (JH) will copy across the data from the data collection form into the Review Manager 5 (RevMan 5) file (RevMan 2014). We will double check that the data is entered correctly by comparing the study reports with how the data are presented in the systematic review. A second review author (NS) will spot‐check study characteristics for accuracy against the study report.
Assessment of risk of bias in included studies
Two review authors (JH and NS) will independently assess risk of bias for each included study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011). We will resolve any disagreement by discussion or by consulting a third review author (JS). We will assess the risk of bias according to the following domains.
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Random sequence generation.
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Allocation concealment.
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Blinding of participants and personnel.
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Blinding of outcome assessment.
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Incomplete outcome data.
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Selective outcome reporting.
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Other bias.
We will grade each potential source of bias as either high, low, or unclear and will provide a quote form the study report together with a justification for our judgment in the 'Risk of bias' table. We will summarise the 'Risk of bias' judgements across different studies for each of the domains listed. We will consider blinding separately for different key outcomes where necessary e.g. for unblinded outcome assessment, risk of bias for all‐cause mortality may be very different than for a patient‐reported pain scale. Where information on risk of bias relates to unpublished data or correspondence with a trial author, we will note this in the 'Risk of bias' table.
When considering treatment effects, we will take into account the risk of bias for the studies that contribute to that outcome.
Assesment of bias in conducting the systematic review
We will conduct the review according to this published protocol and report any deviations form it in the 'Differences between protocol and review' section of the systematic review.
Measures of treatment effect
We will analyse dichotomous data as odds ratios and continuous data as mean difference or standardised mean difference. We will ensure that higher scores for continuous outcomes have the same meaning for the particular outcome, explain the direction to the reader, and report where the directions were reversed if this was necessary.
We will undertake meta‐analyses only where this is meaningful i.e. if the treatments, participants, and the underlying clinical question are similar enough for pooling to make sense.
A common way that trial authors indicate when they have skewed data is by reporting medians and interquartile ranges. When we encounter this we will note that the data is skewed and consider the implication of this.
Where multiple study arms are reported in a single study, we will include only the relevant arms. If two comparisons (e.g. drug A versus placebo and drug B versus placebo) must be entered into the same meta‐analysis, we will halve the control group to avoid double counting.
Unit of analysis issues
We have identified no particular strategies identified for handling non‐standard study designs.
Dealing with missing data
We will contact investigators or study sponsors in order to verify key study characteristics and obtain missing numerical outcome data where possible (e.g. when we identify a study as an abstract only). We will follow intention‐to‐treat principles, where appropriate.
Assessment of heterogeneity
We will use the I² statistic (Higgins 2003) to measure heterogeneity among the studies in each analysis. If we identify substantial heterogeneity we will explore it by prespecified subgroup analysis.
Assessment of reporting biases
If we identify more than 10 studies for any individual parameter, we will produce a funnel plot to explore potential publication bias. If we identify missing data, we will attempt to contact study authors to maximise data completeness. If missing data persists, then we will explore the impact of its omission with sensitivity analysis.
Data synthesis
For quantitative analysis, we will perform a meta‐analysis using RevMan 5 (RevMan 2014) and a random‐effects model (Deeks 2011).
'Summary of findings' table
We will create a 'Summary of findings' table using all primary and secondary outcomes. We will use the five GRADE considerations (study limitations, consistency of effect, imprecision, indirectness, and publication bias) to assess the quality of a body of evidence as it relates to the studies that contribute data to the meta‐analyses for the prespecified outcomes. We will use methods and recommendations described in Section 8.5 and Chapter 12 of the Cochrane Handbook for Systematic Reviews of Interventions (Higgins 2011), and GRADEpro software (GRADEpro 2015). We will justify all decisions to downgrade or upgrade the quality of the evidence using footnotes and will make comments to aid the reader's understanding of the review where necessary. We will consider whether there is any additional outcome information that we are unable to incorporate into meta‐analyses, will note this in the comments, and state if it supports or contradicts the information from the meta‐analyses.
Subgroup analysis and investigation of heterogeneity
We plan to carry out the following subgroup analysis.
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Type of intervention.
The following outcomes will be used in subgroup analysis.
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Return to oral diet without need for procedural intervention (i.e. rigid or flexible oesophagoscopy).
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Serious adverse events (oesophageal perforation, death).
We will use statistical tests to investigate for subgroup interactions.
Sensitivity analysis
We will perform sensitivity analysis defined a priori to assess the robustness of our conclusions. This will involve including only studies at a low risk of bias for all domains in outlined in the 'Risk of bias' section.
Reaching conclusions
We will base our conclusions only on findings from the quantitative or narrative synthesis of included studies for this review. We will avoid making recommendations for practice and our implications for research will give the reader a clear sense if where the focus of any future research in the area should be and what the remaining uncertainties are.
