Quality Assessment of the Studies Included in the Literature Review

ELECTRONIC SUPPLEMENTARY MATERIAL

Quality assessment of the studies included in the literature review

Table S1: Quality assessment table of included articles from the literature review. A modified version of the Newcastle Ottawa Quality Assessment Scale (as detailed in methods section) was used to score each article on specific criteria for ‘selection’ and ‘exposure’ criteria, with each being awarded a maximum of three stars.

Title of study / First Author / Date of Publication / Technique/s for NET localization1 / Selection (3) / Exposure (3)
A controlled comparison of traditional feeding tube verification methods to a bedside, electromagnetic technique [20] / Kearns P / 2001 / EM, Aus, Asp, pH / *** / ***
A multicenter, prospective study of the placement of transpyloric feeding tubes with assistance of a magnetic device [61] / Boivin M / 2000 / Mag / *** / ***
A new technique for placement of nasoenteral feeding tubes using external magnetic guidance [62] / Gabriel S / 1997 / Mag / *** / ***
A new technique for post-pyloric feeding tube placement by palpation in lean critically ill patients [42] / Sekino M / 2012 / Aus / ** / ***
A novel method for insertion of post-pyloric feeding tubes at the bedside without endoscopic or fluoroscopic assistance: A prospective study [67] / Slagt C / 2004 / Aus/ECG / *** / ***
A novel technique for post-pyloric feeding tube placement in critically ill patients: A pilot study [68] / Young R.J / 2005 / EM / ** / ***
A randomized study of a pH sensor feeding tube vs a standard feeding tube in patients requiring enteral nutrition [26] / Botoman VA / 1994 / pH / *** / ***
A simple aspiration test to determine the accuracy of oesophageal placement of fine-bore feeding tubes [69] / Ward M / 2009 / Asp / ** / ***
A simple indicator of correct nasogastric suction tube placement in children and adults [63] / Rulli, F. / 2007 / Illum / * / -
A team-based protocol and electromagnetic technology eliminate feeding tube placement complications [5] / Koopmann M / 2011 / EM / ** / ***
An evaluation of the Cortrak Enteral access system in our intensive care [56] / Dolan M / 2012 / EM / * / **
Bedside placement of pH-guided transpyloric small bowel feeding tubes in critically ill infants and small children [27] / Dimand, R. / 1997 / pH / * / ***
Bedside postpyloric feeding tube placement: A pilot series to validate this novel technique [28] / Gatt M / 2009 / pH / ** / ***
Bedside sonographic control for positional enteral feeding tubes: A controlled study in intensive care unit patients [64] / Gubler, C. / 2006 / UltraS / * / **
Bedside sonographic-guided versus blind nasoenteric feeding tube placement in critically ill patients [40] / Hernandez_Socorro, C. / 1996 / Blind / *** / ***
Capnometry and Air Insufflation for Assessing Initial Placement of Gastric Tubes [45] / Elpern, E. H. / 2007 / Cap, Aus / *** / ***
Colorimetric capnography to ensure correct nasogastric tube position [46] / Meyer, P. / 2009 / Aus/CO2, CO2, Aus / *** / ***
Comparison of four bedside indicators used to predict duodenal feeding tube placement with radiography [21] / Welch SK / 1994 / Aus, pH, Asp, other / *** / ***
Confirmation of nasogastric tube placement by colorimetric indicator detection of carbon dioxide: A preliminary report [47] / Thomas B / 1998 / CO2 / ** / ***
Confirmation of nasogastric tube position by pH testing [29] / Taylor SJ / 2005 / pH / *** / **
Confirmation of transpyloric feeding tube placement by ultrasonography [65] / Greenberg M / 1993 / UltraS / ** / **
Confirming Nasogastric Tube Position in the Emergency Department pH Testing Is Reliable [31] / Stock A / 2008 / pH / ** / -
Determination of a practical pH cutoff level for reliable confirmation of nasogastric tube placement [30] / Gilbertson HR / 2011 / pH / ** / ***
Determining Feeding Tube Location by Gastric and Intestinal pH Values [32] / Phang JS / 2004 / pH / *** / ***
Does the use of an enteral feeding tube with a pH-sensitive tip facilitate enteral nutrition? [33] / Ireton-Jones C / 1993 / pH / ** / **
Effectiveness of pH Measurements in Predicting Feeding Tube Placement [34] / Metheny N / 1989 / pH / ** / ***
Effectiveness of the auscultatory and pH methods in predicting feeding tube placement [16] / Turgay AS / 2010 / pH, Aus / *** / ***
Effectiveness of the auscultatory method in predicting feeding tube location [38] / Metheny, N / 1990 / Aus / * / ***
Electrocardiogram-guided placement of enteral feeding tubes [52] / Keidan I / 2000 / ECG / * / **
Electromagnetic guided feeding tube insertion: Enhancing patient safety [70] / Karmally, Z / 2011 / EM / * / **
Electromagnetic sensor guided nasojejunal tube placement in critically ill patients [71] / Elliot, S / 2010 / EM / * / **
Feasibility and safety of the placement of nasoduodenal feeding tubes by nurses with the assistance of an electromagnetic guidance system (Cortrak) [72] / Mathus-vliegen, E / 2009 / EM / * / ***
Gastric tube placement in young children [36] / Ellett M / 2005 / CO2, pH, Birub / ** / **
Guiding nasoenteral feeding tubes into the distal duodenum with magnets: Results from 161 intubations [73] / Gabriel, S / 1998 / Mag / *** / **
Hold that x-ray: aspirate pH and auscultation prove enteral tube placement [39] / Neumann M / 1995 / Aus, pH / *** / ***
Implementation of an electromagnetic imaging system to facilitate nasogastric and post-pyloric feeding tube placement in patients with and without critical illness [57] / Windle EM / 2010 / EM / ** / ***
Increasing the safety of blind gastric tube placement in pediatric patients: the design and testing of a procedure using a carbon dioxide detection device [41] / Gilbert RT / 2012 / CO2 / ** / **
Indicators of postpyloric feeding tube placement in children [22] / Gharpure V / 2000 / Asp, pH, Bilrub, Enz / *** / ***
Indicators of Tube site During Feedings [23] / Metheny N / 2005 / Asp / *** / **
Intestinal placement of pH-sensing nasointestinal feeding tubes [35] / Berry S / 1994 / pH / * / **
Jejunal tube placement in critically ill patients: A prospective, randomized trial comparing the endoscopic technique with the electromagnetically visualized method [43] / Holzinger, U / 2011 / EM / * / **
Magnetic detection to position human nasogastric tubes [74] / Tobin, R / 2000 / Mag / ** / **
Magnetically guided nasoenteral feeding tubes: a new technique [75] / Gabriel, S / 2001 / Mag / *** / **
Methods to test feeding tube placement in children [24] / Westhus N / 2004 / pH, Enz, Asp, Asp + pH / *** / **
Nasoenteral feeding tube placement by nurses using an electromagnetic guidance system (with video) [58] / Mathus-Vliegen E / 2010 / EM / ** / *
Nasointestinal tube placement with a pH sensor feeding tube [76] / Heiselman D / 1993 / pH / * / **
Noninvasive Verification of Nasogastric Tube Placement Using a Magnet-Tracking System: A Pilot Study in Healthy Subjects [77] / Bercik P / 2005 / Mag / *** / -
Nonradiographic assessment of enteral feeding tube position [78] / Harrison M / 1997 / Aus / *** / **
pH and concentration of bilirubin in feeding tube aspirates as predictors of tube placement [79] / Metheny N / 1999 / Bilrub + pH / *** / *
pH and concentrations of pepsin and trypsin in feeding tube aspirates as predictors of tube placement [80] / Metheny N / 1997 / Enz + pH / *** / **
Placement of nasoenteral feeding tubes using external magnetic guidance [59] / Gabriel S / 2004 / Mag / ** / **
Placement of nasoenteral feeding tubes using magnetic guidance: retesting a new technique [60] / Ozdemir B / 2000 / Mag / ** / **
Placement of nasointestinal ph-sensing feeding tube: A prospective evaluation [81] / Jimenez E / 1998 / pH / *** / **
Prospective randomised comparison study of two methods of jejunal placement of enteral feeding tubes in critically ILL patients: Endoscopic versus electromagnetic visualised method [44] / Holzinger U / 2009 / EM / * / -
Rapid Placement of Transpyloric Feeding Tubes: A Comparison of pH-assisted and Standard Insertion Techniques in Children [82] / Moore L / 1996 / pH / ** / ***
Report on the development of a procedure to prevent placement of feeding tubes into the lungs using end-tidal CO2 measurements [48] / Burns M / 2001 / CO2 / ** / **
Serum paracetamol concentration: an alternative to X-rays to determine feeding tube location in the critically ill [83] / Berger M / 2003 / Other / ** / *
Small bowel feeding tube placement using an electromagnetic tube placement device: Accuracy of tip location [84] / Rivera R / 2011 / EM / ** / ***
Successful placement of postpyloric enteral tubes using electromagnetic guidance in critically ill children [85] / October, T. W / 2009 / EM / * / ***
The effectiveness of ultrasonography in verifying the placement of a nasogastric tube in patients with low consciousness at an emergency center[66] / Kim, H. M / 2012 / pH, Aus, UltrS / *** / **
The use of carbon dioxide monitoring to determine orogastric tube placement in premature infants: a pilot study [49] / Ellett M / 2007 / CO2 / * / **
The use of the Cortrak Enteral Access SystemTM for post-pyloric (PP) feeding tube placement in a Burns Intensive Care Unit [86] / Hemington-Gorse, S. J / 2011 / EM / - / *
Transpyloric feeding tube placement in critically ill patients using electromyogram and erythromycin infusion [53] / Levy H / 2004 / ECG / *** / ***
Ultrasound to confirm gastric tube placement in prehospital management [87] / Chenaitia H / 2012 / UltraS / *** / ***
Use of a colorimetric carbon dioxide sensor for nasoenteric feeding tube placement in critical care patients compared with clinical methods and radiography [50] / Munera-Seeley V / 2008 / CO2 / * / **
Use of a noninvasive electromagnetic device to place transpyloric feeding tubes in critically ill children [54] / Kline, A. M / 2011 / EM / *** / ***
Use of a pressure gauge to differentiate gastric from pulmonary placement of nasoenteral feeding tubes [88] / Swiech K / 1994 / other / ** / ***
Use of an electromagnetic placement device for enteral feeding tubes reduces nursing time and financial burden [89] / Kenar J / 2010 / EM / * / *
Use of capnometry to verify feeding tube placement [51] / Araujo-Preza, C. E / 2002 / CO2 / * / ***
Verification of an electromagnetic placement device compared with abdominal radiograph to predict accuracy of feeding tube placement [55] / Powers J / 2011 / EM / ** / **
Visual Characteristics of Aspirates from Feeding Tubes as a Method for Predicting Tube Location [25] / Metheny N / 1994 / Asp / *** / *

1. Abbreviations for the techniques are shown here:

Abbreviation / Full name of technique
EM / Electromagnetic methods
Aus / Auscultation/insufflation
Asp / Aspirate: Visual inspection
pH / Aspirate: pH testing
Bilrub / Aspirate: Bilirubin testing
Enz / Aspirate: Enzyme testing (pepsin, trypsin)
Mag / External magnet guidance
Illum / Illumination using fibre optic
UltraS / Ultrasound/sonography
Blind / Blind insertion
CO2 / Capnography / Capnometry (colourmetric indicator of end-tidal CO2)
ECG / Electrocardiographic tracing and Electromyography
Bilirub + pH / Combined: Bilirubin and pH
Enz + pH / Combined: Enzyme and pH
Aus/ECG / Combined: Auscultation and ECG
Aus/CO2 / Combined: Auscultation and Capnography / Capnometry
other / vacuum effect (a change from 40mL of aspirated air to <= 10mL after 60 mL of air instillation), paracetamol concentration, Pressure gauge

Determining global appropriateness of methods to confirm NET tip location

Methods

The global appropriateness and applicability of available methods to confirm NET tip location were also evaluated. To do this the performance characteristics of each method were appraised against the needs and requirements of a representative ‘global user base’.

Identifying the ‘global user base’: In order to determine the requirements for a successful global solution, a panel of stakeholders were selected to represent those involved in each stage of the process to confirm the NET tip location; from development to employment. In addition, this panel was comprised of users with various social, economic and geographic perspective. This panel consisted of experienced surgeons with familiarity working in developed and developing nations, two manufacturers / designers with an extensive background in medical device design and marketing, two dieticians and one nurse.

Determining user requirements: The users’ requirements for a successful global solution were obtained by a formal interview process. Each member of the user panel was asked to discuss their experience with various methods, the advantages and disadvantages of the methods they had used and the most important requirements for a successful method. From the interviews performed, a list was compiled of all stated requirements for a method to detect NET tip location.

Weighting the importance of user requirements: Once a full list of requirements had been created, the stakeholders ranked them by importance, from their perspective. This required them to assign a score of importance from 0 (not important at all) to 10 (the most important) to each of the requirements. The stakeholders were then allowed to include additional comments at the end of the survey relating to any adaptations or improvements they would like to see in a new method to confirm NET tip location.

Evaluating the global appropriateness of methods: In order to score the global appropriateness of each method a House of Quality (HOQ) matrix was employed [12, 13]. This is an evaluation matrix that allows the requirements of the user to be mapped against the physical performance characteristics of the method, so that its appropriateness as a technique can be directly determined. A schematic of a HOQ matrix (Figure S1) indicates the key input and output sections of this analysis. User input sections are populated using data derived from user interviews and the importance ranking exercise as described above. The reviewer input sections can be completed by using literature or the results from a trial, or in the case of a new concept, the design specifications, and results from concept stage testing. The interaction matrix sections are completed by moving through each of the performance characteristics and looking for any interaction / correlation (positive or negative) with any of the other performance characteristics, and / or the user requirements, e.g. the performance characteristic of price per disposable tube is negatively correlated to the user requirement of low cost per tube and positively correlated to the performance characteristic of durability of the tube. The completed top of house and inside house matrices can be used to determine which performance criteria are the most interrelated and have the strongest connection to the user requirements. This is done for each performance characteristic with a weighted sum of how many points of interaction they have with other performance characteristic (top of house) and user requirements (inside house). The weighting is based on the strength of correlation as shown in Table S2. Thus the key output from this HOQ matrix is the weighted importance of the performance characteristics for a NET tip location method. The importance weightings are the combination of the weightings of the user requirements and the interaction matrices. These weights allow the review of current methods from the perspective of the ‘global user base’ and can inform a targeted approach to designing a new or improved method.

FigureS1: Schematic of House of Quality matrix

Table S2: Weightings and symbol for the matrix correlation indicators for House of Quality analysis.

Matrix / Description / Weighting / Symbol
Top of house / Positive correlation / 1 / +
Strong positive correlation / 2 / ++
Negative correlation / 1 / -
Strong negative correlation / 2 / --
Inside house / Strong relationship / 3 / Θ
Moderate relationship / 2 / Ο
Weak relationship / 1 / ▲

Table S3: Stakeholder requirements and ranking of importance

Stakeholders
Stakeholder requirement / Clinician (Developing nation experience) / General surgeon / Dietician / Manufacturer/ Designer / Ranked Average
High successful placement rate / 8.0 / 10.0 / 9.0 / 9.0 / 9.0
Low risk to patients / 6.0 / 10.0 / 10.0 / 9.0 / 8.8
Universal language suitability/suitable for illiterate users / 9.0 / 8.0 / 9.0 / 8.0 / 8.5
Low learning curve/training required / 9.0 / 9.0 / 7.0 / 9.0 / 8.5
Viable cost of materials / 8.0 / 8.0 / 9.0 / 8.0 / 8.3
Low Price / 9.0 / 8.0 / 8.0 / 8.0 / 8.3
Viable cost for manufacturing / 8.0 / 8.0 / 7.0 / 8.0 / 7.8
Minimal maintenance required / 9.0 / 7.0 / 8.0 / 7.0 / 7.8
Durable tube / 9.0 / 7.0 / 10.0 / 5.0 / 7.8
Comfort not reduced / 7.0 / 8.0 / 9.0 / 6.0 / 7.5
Relevant design expertise available / 8.0 / 6.0 / 8.0 / 7.0 / 7.3
Ease of use (ergonomic) / 6.0 / 8.0 / 7.0 / 8.0 / 7.3
Friendly design for visually impaired operator / 8.0 / 7.0 / 7.0 / 7.0 / 7.3
Friendly design for audiologically impaired operator / 8.0 / 7.0 / 7.0 / 7.0 / 7.3
Non-perishable product / 9.0 / 7.0 / 8.0 / 4.0 / 7.0
Sterile/can be sterilised / 6.0 / 7.0 / 10.0 / 5.0 / 7.0
Reliable supply of materials / 8.0 / 5.0 / 8.0 / 6.0 / 6.8
Minimal extra disposables required (beyond tubes) / 8.0 / 5.0 / 6.0 / 8.0 / 6.8
Low/no power requirement / 9.0 / 6.0 / 4.0 / 7.0 / 6.5
FDA/appropriate certificate/approval obtained / 5.0 / 7.0 / 6.0 / 6.0 / 6.0
Low environmental impact / 4.0 / 6.0 / 4.0 / 7.0 / 5.3
Time for development / 5.0 / 2.0 / 6.0 / 4.0 / 4.3
High product packing density / 5.0 / 2.0 / 6.0 / 4.0 / 4.3
Low patent presence of similar technology / 0.0 / 1.0 / 8.0 / 6.0 / 3.8

Table S4 The results of the ‘top of house’ interaction matrix analysis, ranking the most interrelated performance criteria.

Performance criteria / Level of interrelation
Success rate (Specificity, sensitivity) / 9
Market size (number of tubes, $$ for devices) / 8
Lifetime of disposable / 8
Size / 7
Cost per tube for disposables / 7
Cost for non-disposable components / 7
Approved/certificated / 7
Power supply (V) / 6
Patient discomfort/pain rating during procedure / 6
Size of visual indicators / 6
Lifetime of non-disposable portion (time before required maintenance/disposal) / 6
Duration of procedure / 5
Weight / 5
Toxicity of materials / 5
Training required / 4
Predicted rate of use of disposables (per patient) / 4
No words - uniformly recognisable symbols only / 4
No Audible only alarms/signals / 3
Lead time on products / 2

Table S5: The results of the ‘inside of house’ interaction matrix analysis, ranking the most interrelated performance criteria with user requiremen.

Performance criteria / Level of interrelation
Cost per tube/disposables / 34
Lifetime of non-disposable portion (time before required maintenance/disposal) / 29
Success rate (Specificity, sensitivity) / 27
Cost for non-disposable components / 26
Market size (number of tubes, $$ for devices) / 25
Lifetime of disposable / 25
Power supply (V) / 25
Toxicity of materials / 25
Predicted rate of use of disposables (per patient) / 23
Training required / 20
Approved/certificated / 16
Duration of procedure / 12
No words - uniformly recognisable symbols only / 12
Size / 11
Size of visual indicators / 10
No Audible only alarms/signals / 10
Patient discomfort/pain rating during procedure / 9
Weight / 9
Lead time on products / 8

Table S6: The ‘House of Quality’ performance criteria ranked by average importance to stakeholders

Stakeholders
Performance criteria / Clinician / General surgeon / Dietician / Manufacturer / Designer / Ranked
Average
Cost per tube/disposables / 10.1 / 9.3 / 9.5 / 9.6 / 9.6
Success rate / 8.3 / 9.8 / 8.9 / 9.3 / 9.1
Cost for non-disposable components / 8.6 / 8.1 / 8.0 / 8.2 / 8.2
Lifetime of non-disposable portion / 8.9 / 7.7 / 7.9 / 8.0 / 8.1
Lifetime of disposable / 7.8 / 7.8 / 8.2 / 7.3 / 7.8
Predicted rate of use of disposables (per patient) / 7.0 / 6.6 / 7.0 / 6.3 / 6.7
Power supply (V) / 7.1 / 6.5 / 6.4 / 6.9 / 6.7
Toxicity of materials / 5.9 / 6.5 / 6.4 / 6.1 / 6.2
Training required / 5.8 / 6.5 / 6.0 / 6.3 / 6.2
Market size (number of tubes, $$ for devices) / 5.1 / 5.3 / 6.1 / 6.1 / 5.6
Approved/certificated / 4.2 / 5.0 / 4.7 / 4.4 / 4.6
No words - uniformly recognisable symbols only / 3.8 / 3.7 / 3.3 / 3.8 / 3.7
Patient discomfort/pain rating during procedure / 2.6 / 3.5 / 3.3 / 3.0 / 3.1
Duration of procedure / 2.8 / 3.2 / 3.0 / 2.9 / 3.0
Size / 2.6 / 2.5 / 2.7 / 2.8 / 2.7
Size of visual indicators / 2.5 / 2.5 / 2.2 / 2.5 / 2.4
Weight / 2.3 / 2.0 / 2.2 / 2.5 / 2.3
Lead time on products / 2.4 / 1.5 / 2.5 / 2.0 / 2.1
No Audible only alarms/signals / 2.2 / 2.0 / 1.8 / 2.1 / 2.0

1