pH and concentration of bilirubin in feeding tube aspirates as predictors of tube placement

Carbon dioxide detection for diagnosis of inadvertent respiratory tract placement of enterogastric tubes in children

BACKGROUND

The insertion of an enterogastric tube (oral or nasal) (EGT) is the passage of a tube through the nose or mouth into the stomach. In a paediatric setting, EGTs are used within clinical practice for a variety of reasons including enteral feeding, decompression, post-gastrointestinal surgery, patient assessment, and drug and fluid administration. Confirmation of EGT placement is required immediately following insertion and thereafter prior to each use, including after the administration of enteral feed or medication. Although the majority of these tubes are inserted and used without incident, there is an established risk that the tube can be misplaced into the lungs or move out of the stomach. This misplacement can result in significant harm or mortality. As such, diagnostic tests are required to assess the placement of EGTs and to rule out the target condition of potential airway placement. Various methods are used to determine EGT position, including bedside assessment and observing for signs of respiratory distress. Air insufflated (blown) through the EGT in combination with epigastric auscultation (listening to the stomach with a stethoscope) for whooshing sounds has also been used. Although these tests are widely recognised, they are not officially recommended for use as standalone measures of EGT placement. Current American and UK guidelines recommend a combination of aspirate testing and radiological confirmation of EGT placement in infant, child, and adult populations. In adults, objective measures of pH of the aspirate may be used, with a pH reading between 1 and 5.5 considered a reliable method for excluding placement in the pulmonary tree. However, testing for acidity of aspirate obtained from the EGT does not accurately differentiate between bronchial and gastric secretions in paediatric practice. Additionally, there may be difficulty in obtaining aspirate from the EGT especially within a paediatric population due to the size of the EGT and the smaller volumes of gastric secretions produced. Radiography or direct visualisation are the only reliable methods of confirming EGT placement (valid at time of X-ray and point of insertion, respectively) in this population and are thus considered the reference standard. However, within the paediatric population, there is a known difficulty with obtaining radiographs that visualise the entire course of the EGT and a recognised risk in radiation exposure in the paediatric setting. The measurement of carbon dioxide (CO₂) in exhaled air is a recognised and mandatory standard of care for confirming and monitoring endotracheal tube or airway placement under general anaesthesia. The measurement of CO₂ can be achieved in one of two ways: capnography or colorimetric capnometry. Capnography is the measurement of inspired and expired CO₂ using the absorption of infrared light by CO₂ molecules to estimate CO₂ concentrations. These measurements are then displayed against time to give a continual graphical trace. Colorimetric capnometry involves the detection of CO₂ using an adapted form of pH filter paper impregnated with a dye that changes colour from purple to yellow in the presence of CO₂; however, this method does not provide a continual reading. The monitoring of CO₂ emanating from an EGT inadvertently passed into the airways would utilise this phenomenon in a reverse manner, confirming tracheobronchial placement rather than the intended stomach.

OBJECTIVES

To determine the diagnostic accuracy of capnometry and capnography for detecting respiratory EGT placement in children compared to the reference standard.

SEARCH METHODS

We searched the Cochrane Register of Diagnostic Test Accuracy Studies, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, CINAHL, and Medion database on 4 September 2023. There were no limits on language or publication status.

SELECTION CRITERIA

We included studies that compared the diagnostic accuracy of CO₂ detection (assessed by either capnometry or capnography) for EGT placement in the respiratory tract with the reference standard, and those that evaluated the diagnostic accuracy of CO₂ detection for differentiating between respiratory and gastrointestinal tube placement, in children. We included both prospective and retrospective cross-sectional studies. We included diagnostic case-control studies where patients acted as their own controls whereby the same EGT and end placement was tested both via index and reference test concurrently.

DATA COLLECTION AND ANALYSIS

Two review authors independently extracted data and assessed methodological quality using QUADAS-2. There were no disagreements. Where data were available, we reported test accuracy as sensitivity and specificity. Calculation of both sensitivity and specificity with a 95% confidence interval (CI) was only possible for one study. We calculated specificity with a 95% CI for all included studies. Due to the low number of included studies, we were not able to perform meta-analysis or conduct our planned investigations of heterogeneity.

MAIN RESULTS

We identified three studies for inclusion in the review, all of which provided data on test accuracy of capnography or capnometry against the radiological test standard. Across the three studies, there were a total of 121 participants and 139 EGT insertions with low event data for false-positive (n = 6 insertions) and true-positive (n = 3 insertions) scenarios. No event data were available for false-negative scenarios. Overall, the body of evidence has a low risk of bias, although further clarity regarding patient enrolment (whether consecutive or random) and details about the conduct of the index and reference tests would have enhanced the overall quality of the evidence base included in the review.

AUTHORS' CONCLUSIONS

There is currently not enough evidence to suggest that CO₂ detection for inadvertent respiratory tract placement of EGTs in children should be added to current checking procedures. Future studies should aim for larger samples across a range of ages and evaluate different types of CO₂ monitoring (capnography and capnometry), using a range of EGT sizes in participants who are both spontaneously breathing or who require mechanical ventilation with or without impairments of conscious level.

Development of a new endoscopy system to visualize bilirubin for the diagnosis of duodenogastroesophageal reflux

OBJECTIVES

Reflux hypersensitivity (RH) is a form of refractory gastroesophageal reflux disease in which duodenogastroesophageal reflux (DGER) plays a role. This study aimed to determine the usefulness of an endoscopy system equipped with image-enhanced technology for evaluating DGER and RH.

METHODS

The image enhancement mode for detecting bilirubin and calculated values were defined as the Bil mode and Bil value, respectively. First, the visibility of the Bil mode was validated for a bilirubin solution and bile concentrations ranging from 0.01% to 100% (0.002-20 mg/dL). Second, visibility scores of the Bil mode, when applied to the porcine esophagus sprayed with a bilirubin solution, were compared to those of the blue laser imaging (BLI) and white light imaging (WLI) modes. Third, a clinical study was conducted to determine the correlations between esophageal Bil values and the number of nonacid reflux events (NNRE) during multichannel intraluminal impedance-pH monitoring as well as the utility of esophageal Bil values for the differential diagnosis of RH.

RESULTS

Bilirubin solution and bile concentrations higher than 1% were visualized in red using the Bil mode. The visibility score was significantly higher with the Bil mode than with the BLI and WLI modes for 1% to 6% bilirubin solutions (P < 0.05). The esophageal Bil value and NNRE were significantly positively correlated (P = 0.031). The area under the receiver operating characteristic curve for the differential diagnosis of RH was 0.817.

CONCLUSION

The Bil mode can detect bilirubin with high accuracy and could be used to evaluate DGER in clinical practice.

Ultrasonography for confirmation of gastric tube placement

BACKGROUND

Gastric tubes are commonly used for the administration of drugs and tube feeding for people who are unable to swallow. Feeding via a tube misplaced in the trachea can result in severe pneumonia. Therefore, the confirmation of tube placement in the stomach after tube insertion is important. Recent studies have reported that ultrasonography provides good diagnostic accuracy estimates in the confirmation of appropriate tube placement. Hence, ultrasound could provide a promising alternative to X-rays in the confirmation of tube placement, especially in settings where X-ray facilities are unavailable or difficult to access.

OBJECTIVES

To assess the diagnostic accuracy of ultrasound alone or in combination with other methods for gastric tube placement confirmation in children and adults.

SEARCH METHODS

This systematic review is an update of a previously published Cochrane review. For this update, we searched the Cochrane Library (2021, Issue 6), MEDLINE (to April 2023), Embase (to April 2023), five other databases (to July 2021), and reference lists of articles, and contacted study authors.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of naso- and orogastric tube placement confirmed by ultrasound visualization using X-ray visualization as the reference standard. We included cross-sectional studies and case-control studies. We excluded case series or case reports. We excluded studies if X-ray visualization was not the reference standard or if the tube being placed was a gastrostomy or enteric tube.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality and extracted data from each of the included studies. We contacted the authors of the included studies to obtain missing data. There were sparse data for specificity. Therefore, we performed a meta-analysis of only sensitivity using a univariate random-effects logistic regression model to combine data from studies that used the same method and echo window.

MAIN RESULTS

We identified 12 new studies in addition to 10 studies included in the earlier version of this review, totalling 1939 participants and 1944 tube insertions. Overall, we judged the risk of bias in the included studies as low or unclear. No study was at low risk of bias or low concern for applicability in every QUADAS-2 domain. There were limited data (152 participants) for misplacement detection (specificity) due to the low incidence of misplacement. The summary sensitivity of ultrasound on neck and abdomen echo windows were 0.96 (95% confidence interval (CI) 0.92 to 0.98; moderate-certainty evidence) for air injection and 0.98 (95% CI 0.83 to 1.00; moderate-certainty evidence) for saline injection. The summary sensitivity of ultrasound on abdomen echo window was 0.96 (95% CI 0.65 to 1.00; very low-certainty evidence) for air injection and 0.97 (95% CI 0.95 to 0.99; moderate-certainty evidence) for procedures without injection. The certainty of evidence for specificity across all methods was very low due to the very small sample size. For settings where X-ray was not readily available and participants underwent gastric tube insertion for drainage (8 studies, 552 participants), sensitivity estimates of ultrasound in combination with other confirmatory tests ranged from 0.86 to 0.98 and specificity estimates of 1.00 with wide CIs. For studies of ultrasound alone (9 studies, 782 participants), sensitivity estimates ranged from 0.77 to 0.98 and specificity estimates were 1.00 with wide CIs or not estimable due to no occurrence of misplacement.

AUTHORS' CONCLUSIONS

Of 22 studies that assessed the diagnostic accuracy of gastric tube placement, few studies had a low risk of bias. Based on limited evidence, ultrasound does not have sufficient accuracy as a single test to confirm gastric tube placement. However, in settings where X-ray is not readily available, ultrasound may be useful to detect misplaced gastric tubes. Larger studies are needed to determine the possibility of adverse events when ultrasound is used to confirm tube placement.

Performance of Point-of-Care Ultrasonography in Confirming Feeding Tube Placement in Mechanically Ventilated Patients

BACKGROUND

A feeding tube (FT) is routinely placed in critically ill patients, and its correct placement is confirmed with a chest X-ray (CXR), which is considered the gold standard. This study evaluated the diagnostic accuracy of ultrasonography (USG) in verifying FT placement compared to a CXR in an intensive care unit (ICU).

METHOD

This was a prospective single-blind study conducted on patients admitted to the ICU of a tertiary hospital in Malaysia. The FT placements were verified through a fogging test and USG at the neck and subxiphoid points. The results of confirmation of FT placement through USG were compared with those obtained using CXRs.

RESULTS

A total of 80 patients were included in this study. The FT positions were accurately confirmed by overall USG assessments in 71 patients. The percentage of FT placements correctly identified by neck USG was 97.5%, while the percentage of those identified by epigastric USG was 75%. The corresponding patients' CXRs confirmed correct FT placement in 76 patients. The overall USG assessment had a sensitivity of 92.11% and specificity of 75%, a positive predictive value of 98.59%, and a negative predictive value of 33.33%. The USG findings also showed a significant association between FT size and BMI. FTs with a size of 14Fr were better visualized (p = 0.008), and negative USG findings had a significantly higher BMI (p < 0.001).

CONCLUSION

USG is a simple, safe, and reliable bedside assessment that offers relatively high sensitivity in confirming correct FT placement in critically ill patients.

Electromagnetic-guided versus endoscopic-guided postpyloric placement of nasoenteral feeding tubes

BACKGROUND

For people who are malnourished and unable to consume food by mouth, nasoenteral feeding tubes are commonly used for the administration of liquid food and drugs. Postpyloric placement is when the tip of the feeding tube is placed beyond the pylorus, in the small intestine.  Endoscopic-guided placement of postpyloric feeding tubes is the most common approach. Usually, an endoscopist and two or more medical professionals perform this procedure using a guidewire technique. The position of the tube is then confirmed with fluoroscopy or radiography, which requires moving people undergoing the procedure to the radiology department. Alternatively, electromagnetic-guided placement of postpyloric nasoenteral feeding tubes can be performed by a single trained nurse, at the bedside and with less equipment than endoscopic-guided placement. Hence, electromagnetic-guided placement may represent a promising alternative to endoscopic-guided placement, especially in settings where endoscopy and radiographic facilities are unavailable or difficult to access.

OBJECTIVES

To assess the efficacy and safety of electromagnetic-guided placement of postpyloric nasoenteral feeding tubes compared to endoscopic-guided placement.

SEARCH METHODS

We searched the Cochrane Library, MEDLINE, Embase, CINAHL, ClinicalTrials.gov, World Health Organization International Clinical Trials Registry Platform, and OpenGrey until February 2021. We screened the reference lists of relevant review articles and current treatment guidelines for further literature. We contacted the study authors for missing data.

SELECTION CRITERIA

We included randomised trials comparing electromagnetic-guided placement with endoscopic-guided placement of nasoenteral feeding tubes. We excluded prospective cohort studies, retrospective cohort studies, (nested) case-control studies, cross-sectional studies, and case series or case reports.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the methodological quality of potentially eligible trials and extracted data from the included trials. The primary outcomes were technical success in insertion and aspiration pneumonitis. The secondary outcomes were the time for postpyloric placement of nasoenteral feeding tubes, direct healthcare costs, and adverse events. We performed a random-effects meta-analysis. We calculated risk ratios (RRs) with 95% confidence intervals (CIs) for dichotomous outcomes and mean differences (MDs) with 95% CIs for continuous outcomes. We evaluated the certainty of evidence based on the GRADE approach.

MAIN RESULTS

We identified four randomised controlled trials with 541 participants which met our inclusion criteria. All trials had methodological limitations, and lack of blinding of participants and investigators was a major source of bias. We had 'some concerns' for the overall risk of bias in all trials.  Electromagnetic-guided postpyloric placement of nasoenteral feeding tubes may result in little to no difference in technical success in insertion compared to endoscopic-guided placement (RR 1.09, 95% CI 0.88 to 1.35; I2 = 81%; low-certainty evidence). Electromagnetic-guided placement may result in a difference in the proportion of participants with aspiration pneumonitis compared to endoscopic-guided placement, but these results are unclear (RR 0.24, 95% CI 0.03 to 2.18; I2 = 0%; low-certainty evidence).  Electromagnetic-guided placement may result in little to no difference in the time for postpyloric placement of nasoenteral feeding tubes compared to endoscopic-guided placement (MD 4.06 minutes, 95% CI -0.47 to 8.59; I2 = 97%; low-certainty evidence). Electromagnetic-guided placement likely reduces direct healthcare costs compared to endoscopic-guided placement (MD -127.69 US dollars, 95% CI -135.71 to -119.67; moderate-certainty evidence). Electromagnetic-guided placement likely results in little to no difference in adverse events compared with endoscopic-guided placement (RR 0.78, 95% CI 0.41 to 1.49; moderate-certainty evidence).

AUTHORS' CONCLUSIONS

We found low-certainty evidence that electromagnetic-guided placement at the bedside results in little to no difference in technical success in insertion and aspiration pneumonitis, compared to endoscopic-guided placement. The heterogeneity of the healthcare professionals who performed the procedures and the small sample sizes limited our confidence in the evidence. Future research should be based on large studies with well-defined endpoints to potentially elucidate the differences between these two procedures.

Development and validation of ester impregnated pH strips for locating nasogastric feeding tubes in the stomach-a multicentre prospective diagnostic performance study

BACKGROUND

NG (nasogastric) tubes are used worldwide as a means to provide enteral nutrition. Testing the pH of tube aspirates prior to feeding is commonly used to verify tube location before feeding or medication. A pH at or lower than 5.5 was taken as evidence for stomach intubation. However, the existing standard pH strips lack sensitivity, especially in patients receiving feeding and antacids medication. We developed and validated a first-generation ester-impregnated pH strip test to improve the accuracy towards gastric placements in adult population receiving routine NG-tube feeding. The sensitivity was improved by its augmentation with the action of human gastric lipase (HGL), an enzyme specific to the stomach.

METHODS

We carried out a multi-centred, prospective, two-gate diagnostic accuracy study on patients who require routine NG-tube feeding in 10 NHS hospitals comparing the sensitivity of the novel pH strip to the standard pH test, using either chest X-rays or, in its absence, clinical observation of the absence of adverse events as the reference standard. We also tested the novel pH strips in lung aspirates from patients undergoing oesophageal cancer surgeries using visual inspection as the reference standard. We simulated health economics using a decision analytic model and carried out adoption studies to understand its route to commercialisation. The primary end point is the sensitivity of novel and standard pH tests at the recommended pH cut-off of 5.5.

RESULTS

A total of 6400 ester-impregnated pH strips were prepared based on an ISO13485 quality management system. A total of 376 gastric samples were collected from adult patients in 10 NHS hospitals who were receiving routine NG-tube feeding. The sensitivities of the standard and novel pH tests were respectively 49.2% (95% CI 44.1‑54.3%) and 70.2% (95% CI 65.6‑74.8%) under pH cut-off of 5.5 and the novel test has a lung specificity of 89.5% (95% CI 79.6%, 99.4%). Our simulation showed that using the novel test can potentially save 132 unnecessary chest X-rays per check per every 1000 eligible patients, or direct savings of £4034 to the NHS.

CONCLUSIONS

The novel pH test correctly identified significantly more patients with tubes located inside the stomach compared to the standard pH test used widely by the NHS.

TRIAL REGISTRATION

http://www.isrctn.com/ISRCTN11170249 , Registered 21 June 2017-retrospectively registered.

Nasogastric Tube Feeding in Older Patients: A Review of Current Practice and Challenges Faced

Nasogastric tube feeding is an essential way of delivering enteral nutrition when the oral route is insufficient or unsafe. Malnutrition is recognised as a reversible factor for sarcopenia and frailty. It is therefore crucial that malnutrition is treated in older inpatients who have dysphagia and require enteral nutrition. Despite five National Patient Safety Alerts since 2005, “Never Events” related to nasogastric feeding persist. In addition to placement errors, current practice often leads to delays in feeding, which subsequently result in worse patient outcomes. It is crucial that tube placement is confirmed accurately and in a timely way. Medical advancements in this area have been slow to find a solution which meets this need. In this paper, we provide an updated review on the current use of feeding nasogastric tubes in the older population, the issues associated with confirming correct placement, and innovative solutions for improving safety and outcomes in older patients.

The proton-sensing receptor ovarian cancer G-protein coupled receptor 1 (OGR1) in airway physiology and disease

Numerous G protein-coupled receptors (GPCRs) regulate multiple airway functions and play fundamental roles in normal and aberrant airway and lung physiology. Thus, GPCRs are prime candidates of targeting by disease therapeutics. The intriguing proton-sensing GPCR Ovarian cancer G-protein coupled receptor 1 (OGR1; aka GPR68) has recently been shown capable of regulating airway smooth muscle (ASM) contraction and proliferation. Although the study of OGR1 has been confounded by the fact that the proton is the presumed cognate ligand of OGR1, recent studies have begun to identify novel ligands and modulators capable of regulating the diverse signaling, and functional role of OGR1. Such studies offer hope for OGR1-targeting drugs as therapeutics for obstructive lung diseases such as asthma. Herein, we review the literature to date detailing the receptor biology and pharmacology of OGR1, receptor function in the airway, and describe the potential clinical utility of OGR1-modulating drugs.

Pneumothorax from Intrapleural Placement of a Nasogastric Tube

Nasogastric tube insertion is a commonly performed procedure that can be associated with significant morbidity and even mortality. There is no universally accepted technique to confirm correct placement. Most confirmatory methods are performed after placement, therefore misplacement and potential complications may have already occurred. We report a case where a commonly used bedside confirmatory test gave false reassurance that the nasogastric tube was properly positioned, but a plain chest X-ray revealed a massive pneumothorax due to inadvertent intrapleural placement of the tube. Due to the deficiencies of traditional confirmatory bedside techniques, and the limitations of modern and more sophisticated confirmatory methods, the plain chest X-ray remains the gold standard test to confirm correct nasogastric tube placement. We appraise the methods commonly employed to confirm nasogastric tube placement, and discuss factors that may increase the risk of misplacement.

Bile Gastritis Following Laparoscopic Single Anastomosis Gastric Bypass: Pilot Study to Assess Significance of Bilirubin Level in Gastric Aspirate

INTRODUCTION

Laparoscopic single anastomosis gastric bypass (SAGB) is increasingly performed for morbidly obese patients.

AIM OF WORK

This pilot study aims primarily at evaluating the incidence of bile gastritis after SAGB. The occurrence of reflux oesophagitis and reflux symptoms were also assessed.

PATIENTS AND METHODS

This study included 20 patients having no reflux symptoms. All patients underwent a SAGB as a primary bariatric procedure by a single surgeon. Patients included consented to have an upper GI endoscopy done at 6 months postoperatively. Gastric aspirate was sent for bilirubin level assessment. Gastric and esophageal biopsies were submitted for histopathology and campylobacter-like organism (CLO) test.

RESULTS

In our study, the rate of bile gastritis was 30%. In 18 patients, the level of bilirubin in gastric aspirate seems to be related to the degree of mucosal inflammation. The remaining two patients had microscopic moderate to severe gastritis with normal aspirate bilirubin level. Two patients with bilirubin level in aspirate more than 20 mg/dl had severe oesophagitis, gastritis with erosions, and metaplasia. Relationship between bilirubin level and histopathological findings of gastric biopsy examination was statistically significant with a P value of 0.001.

CONCLUSION

The incidence of bile gastritis in this cohort is higher than reported in the literature, and this may be worrying. The correlation between endoscopic findings and patients' symptoms is poor. Bilirubin level and pH in aspirate might be useful tools to confirm alkaline reflux. Its level might help to choose candidates for revision surgery after SAGB. This needs further validation with larger sample size.

Nasogastric tube placement confirmation: where we are and where we should be heading

Background:

Insertion of a tube via the nasal passage is a common procedure which has been practiced for many years. There are various ways to assess the position of the nasogastric tube (NGT).

Objectives:

The objective of this study was to discuss the advantages and limitations of each method of NGT placement confirmation, to identify gaps in literature, and provide suggestions for future research.

Methods:

A search was performed with Pubmed, CINAHL, and Embase. The following keywords were used: “nasogastric,” “tube,” “placement,” “insertion,” and “measurement.” The results were narrowed down to those with full text available, published in the English language, those published within the last 10 years, and those studies done in the adult population. The reference lists of those articles were also referred to and relevant articles were retrieved. A final 26 relevant articles were included in this review, including six that were published more than 10 years ago but still relevant in this review.

Results:

A method to confirm NGT placement that is accurate, affordable, does not require gastric aspirates, and is able to be used not only upon insertion but also at regular intervals is lacking.

Conclusions:

This article provides a summary of the different methods of NGT placement confirmation and discusses their advantages and limitations. Gaps in literature and suggestions for future research were also deliberated.

Ultrasonography for confirmation of gastric tube placement

BACKGROUND

Gastric tubes are commonly used for the administration of drugs and tube feeding for people who are unable to swallow. Feeding via a tube misplaced in the trachea can result in severe pneumonia. Therefore, the confirmation of tube placement in the stomach after tube insertion is important. Recent studies have reported that ultrasonography provides good diagnostic accuracy estimates in the confirmation of appropriate tube placement. Hence, ultrasound could provide a promising alternative to X-rays in the confirmation of tube placement, especially in settings where X-ray facilities are unavailable or difficult to access.

OBJECTIVES

To assess the diagnostic accuracy of ultrasound for gastric tube placement confirmation.

SEARCH METHODS

We searched the Cochrane Library (2016, Issue 3), MEDLINE (to March 2016), Embase (to March 2016), National Institute for Health Research (NIHR) PROSPERO Register (to May 2016), Aggressive Research Intelligence Facility Databases (to May 2016), ClinicalTrials.gov (to May 2016), ISRCTN registry (May 2016), World Health Organization International Clinical Trials Registry Platform (to May 2016) and reference lists of articles, and contacted study authors.

SELECTION CRITERIA

We included studies that evaluated the diagnostic accuracy of naso- and orogastric tube placement confirmed by ultrasound visualization using X-ray visualization as the reference standard. We included cross-sectional studies, and case-control studies. We excluded case series or case reports. Studies were excluded if X-ray visualization was not the reference standard or if the tube being placed was a gastrostomy or enteric tube.

DATA COLLECTION AND ANALYSIS

Two review authors independently assessed the risk of bias and extracted data from each of the included studies. We contacted authors of the included studies to obtain missing data.

MAIN RESULTS

We identified 10 studies (545 participants and 560 tube insertions) which met our inclusion criteria.No study was assigned low risk of bias or low concern in every QUADAS-2 domain. We judged only three (30%) studies to have low risk of bias in the participant selection domain because they performed ultrasound after they confirmed correct position by other methods.Few data (43 participants) were available for misplacement detection (specificity) due to the low incidence of misplacement. We did not perform a meta-analysis because of considerable heterogeneity of the index test such as the difference of echo window, the combination of ultrasound with other confirmation methods (e.g. saline flush visualization by ultrasound) and ultrasound during the insertion of the tube. For all settings, sensitivity estimates for individual studies ranged from 0.50 to 1.00 and specificity estimates from 0.17 to 1.00. For settings where X-ray was not readily available and participants underwent gastric tube insertion for drainage (four studies, 305 participants), sensitivity estimates of ultrasound in combination with other confirmatory tests ranged from 0.86 to 0.98 and specificity estimates of 1.00 with wide confidence intervals.For the studies using ultrasound alone (four studies, 314 participants), sensitivity estimates ranged from 0.91 to 0.98 and specificity estimates from 0.67 to 1.00.

AUTHORS' CONCLUSIONS

Of 10 studies that assessed the diagnostic accuracy of gastric tube placement, few studies had a low risk of bias. Based on limited evidence, ultrasound does not have sufficient accuracy as a single test to confirm gastric tube placement. However, in settings where X-ray is not readily available, ultrasound may be useful to detect misplaced gastric tubes. Larger studies are needed to determine the possibility of adverse events when ultrasound is used to confirm tube placement.

Monitoring Feeding Tube Placement

The purpose of this literature review is to describe currently available bedside methods to determine feeding tube placement. Described first are methods used at the time of blind insertion to distinguish between gastric and respiratory placement and gastric and small-bowel placement. Discussed next are methods used after feedings are initiated to determine if the tube has remained in the desired position in the gastrointestinal tract. Some of the methods are research-based, whereas others are opinion-based. The level of accuracy of the methods discussed in the review varies widely. No sure non-radiographic method exists to differentiate between respiratory, esophageal, gastric, and small bowel placement of blindly inserted feeding tubes in the fed or unfed state. However, a combination of some of the simpler and more accurate methods may be used to guide feeding tube placement during insertion and help identify the point at which an abdominal radiograph is most likely to confirm the desired location. In addition, methods described in this review can help determine when a radiograph is needed to confirm that a feeding tube has remained in the correct position after the initiation of feedings. Minimizing the number of radiographs taken to assure correct tube placement is important, especially in young children and in the critical care setting where the need for radiographs for other reasons is common.

4-Point ultrasonography to confirm the correct position of the nasogastric tube in 114 critically ill patients

PURPOSE

Nasogastric feeding tube is routinely positioned in intensive care units. The complications of misplacement are rare but very dangerous for the patients. The aim of this study is to estimate the diagnostic accuracy of this new technique, 4-point ultrasonography to confirm nasogastric tube placement in intensive care.

METHODS

One hundred fourteen critical ill patients monitored in ICU were included. The intensivist provided in real time to perform the exam in four steps: sonography from either the right or left side of the patient's neck to visualize the esophagus, sonography of epigastrium to confirm the passage through the esophagogastric junction and the positioning in antrum, sonography of the fundus. Finally, gastric placement of the nasogastric feeding tube was confirmed with thorax radiograph.

RESULTS

One hundred fourteen of the gastric tubes were visualized by sonography in the digestive tract and all were confirmed by radiography (sensitivity 100%). The entire sonographic procedure, including the longitudinal and transversal scan of the esophagus, the esophagogastric junction, the antrum and the fundus, took 10 min.

CONCLUSIONS

Our pilot study demonstrated that not weighted-tip gastric tube routinely used in Intensive Care is visible with the sonography. The pilot study confirmed the high sensitivity of the sonography in the verify correct positioning of gastric tube in the adult ICU patients. The ultrasound examination seems to be easy and rapid even when performed by a intensivist whit a sonographic training of only 40 h. The sonographic exam at the bedside was performed in a shorter time than the acquisition and reporting of the X-ray.

Naso-enteric Tube Placement: A Review of Methods to Confirm Tip Location, Global Applicability and Requirements

BACKGROUND

The insertion of a tube through the nose and into the stomach or beyond is a common clinical procedure for feeding and decompression. The safety, accuracy and reliability of tube insertion and methods used to confirm the location of the naso-enteric tube (NET) tip have not been systematically reviewed. The aim of this study is to review and compare these methods and determine their global applicability by end-user engagement.

METHODS

A systematic literature review of four major databases was performed to identify all relevant studies. The methods for NET tip localization were then compared for their accuracy with reference to a gold standard method (radiography or endoscopy). The global applicability of the different methods was analysed using a house of quality matrix.

RESULTS

After applying the inclusion and exclusion criteria, 76 articles were selected. Limitations were found to be associated with the 20 different methods described for NET tip localization. The method with the best combined sensitivity and specificity (where n > 1) was ultrasound/sonography, followed by external magnetic guidance, electromagnetic methods and then capnography/capnometry. The top three performance criteria that were considered most important for global applicability were cost per tube/disposable, success rate and cost for non-disposable components.

CONCLUSION

There is no ideal method for confirming NET tip localisation. While radiography (the gold standard used for comparison) and ultrasound were the most accurate methods, they are costly and not universally available. There remains the need to develop a low-cost, easy-use, accurate and reliable method for NET tip localization.

Examining the evidence to guide practice: challenging practice habits

Nurses are the largest segment of the nation's health care workforce, which makes nurses vital to the translation of evidence-based practice as a practice norm. Critical care nurses are in a position to critically appraise and apply best evidence in daily practice to improve patients' outcomes. It is important for critical care nurses to continually evaluate their current practice to ensure that they are applying the current best evidence rather than practicing on the basis of tradition. This article is based on a presentation at the 2013 National Teaching Institute of the American Association of Critical-Care Nurses. Four practice interventions that are within the realm of nursing are critiqued on the basis of current best evidence: (1) turning critically ill patients, (2) sleep promotion in the intensive care unit, (3) feeding tube management in infants and children, and (4) prevention of venothromboembolism…again. The related beliefs, current evidence, and implications for practice associated with each topic are described.

Comparing bedside methods of determining placement of gastric tubes in children

PURPOSE

The purpose of this study was to compare the accuracy and predictive validity of pH, bilirubin, and CO2 in identifying gastric tube placement errors in children.

DESIGN AND METHODS

After the tube was inserted into 276 children, the CO2 monitor reading was obtained. Fluid was then aspirated to test pH and bilirubin.

RESULTS

Lack of ability to obtain tube aspirate was the best predictor of NG/OG placement errors with a sensitivity of 34.9% and a positive predictive value of 66.7%. Measuring pH, bilirubin, and CO2 of tube aspirate was less helpful.

PRACTICE IMPLICATIONS

Healthcare providers should suspect NG/OG tube misplacement when no fluid is aspirated.

A review of published case reports of inadvertent pulmonary placement of nasogastric tubes in children

PROBLEM

Little is known about the incidence of inadvertent pulmonary placement of nasogastric tubes during blind insertions in children.

PURPOSE

The purpose of this paper was to conduct a review of published case reports over the past two decades.

METHODS

An OVID Medline search was conducted of articles published from 1993 through 2012.

RESULTS

Fifteen published case reports were located; four patients died as a result of their malpositioned tubes. The auscultatory bedside method failed to detect the malpositioned tubes in all seven cases in which it was used.

CONCLUSIONS

The incidence of inadvertent pulmonary placement of nasogastric tubes is relatively low but can lead to serious and even lethal results in children. The auscultatory method to predict tube location is unreliable.

The GPCR OGR1 (GPR68) mediates diverse signalling and contraction of airway smooth muscle in response to small reductions in extracellular pH

BACKGROUND AND PURPOSE

Previous studies have linked a reduction in pH in airway, caused by either environmental factors, microaspiration of gastric acid or inflammation, with airway smooth muscle (ASM) contraction and increased airway resistance. Neural mechanisms have been shown to mediate airway contraction in response to reductions in airway pH to < 6.5; whether reduced extracellular pH (pHo) has direct effects on ASM is unknown.

EXPERIMENTAL APPROACH

Intracellular signalling events stimulated by reduced pHo in human cultured ASM cells were examined by immunoblotting, phosphoinositide hydrolysis and calcium mobilization assays. ASM cell contractile state was examined using magnetic twisting cytometry. The expression of putative proton-sensing GPCRs in ASM was assessed by real-time PCR. The role of ovarian cancer G protein-coupled receptor 1 (OGR1 or GPR68) in acid-induced ASM signalling and contraction was assessed in cultures subjected to siRNA-mediated OGR1 knockdown.

KEY RESULTS

ASM cells responded to incremental reductions in pHo (from pH 8.0 to pH 6.8) by activating multiple signalling pathways, involving p42/p44, PKB, PKA and calcium mobilization. Coincidently, ASM cells contracted in response to decreased pHo with similar 'dose'-dependence. Real-time PCR suggested OGR1 was the only proton-sensing GPCR expressed in ASM cells. Both acid-induced signalling (with the exception of PKB activation) and contraction were significantly attenuated by knockdown of OGR1.

CONCLUSIONS AND IMPLICATIONS

These studies reveal OGR1 to be a physiologically relevant GPCR in ASM cells, capable of pleiotropic signalling and mediating contraction in response to small reductions in extracellular pH. Accordingly, ASM OGR1 may contribute to asthma pathology and represent a therapeutic target in obstructive lung diseases.

Enteral feeding tubes: are insertion techniques and positioning based on anatomical evidence?

Patients in whom oral energy intake is insufficient for daily needs may develop malnutrition and its complications, such as increased infection rates, increased length of hospitalization, and death. Enteral feeding is beneficial for these patients. However, this therapy is not without complications related to the insertion and placement of enteral feeding tubes. This review aims to identify from the literature different techniques for insertion and the methods used to evaluate the placement of enteral feeding tubes.

Predicting the insertion length for gastric tube placement in neonates

OBJECTIVE

To compare error rates of three existing methods of predicting the gastric tube insertion length in a group of neonates <1 month corrected age: age-related, height-based (ARHB); direct distance nose-ear-xiphoid (NEX); and direct distance nose-ear-mid-umbilicus (NEMU).

DESIGN

Randomized controlled trial.

SETTING

Five neonatal care units in a large midwestern city.

PARTICIPANTS

One hundred and seventy-three hospitalized neonates.

METHODS

Neonates were randomly assigned to one of three groups: ARHB, NEX, or NEMU. For primary analysis, only tubes placed too high with the tube tip in the esophagus or at the gastroesophageal junction were considered to be misplaced. For secondary analysis, a stricter definition was used, and low placements (pylorus or duodenum) were also considered to be misplaced. All radiographs were blinded and read by a pediatric radiologist.

RESULTS

For the primary analysis, the differences in percentages of correctly placed tubes among the three methods was statistically significant (χ(2) =34.45; p<.0001), with NEMU and ARHB more accurate than NEX (NEMU χ(2) =18.59, p<.0001; ARHB χ(2) =21.34, p<.0001). Using the stricter definition for placement, ARHB was not significantly different from NEX (p=.0615). A new ARHB equation was developed specific for neonates <1 month corrected age.

CONCLUSIONS

Direct distance nose-ear-xiphoid should no longer be used as an nasogastric/orogastric (NG/OG) tube insertion-length predictor in neonates. Either NEMU for NG/OG tubes or the new ARHB equation for NG tubes should be used.

Practical approach to paediatric enteral nutrition: a comment by the ESPGHAN committee on nutrition

Enteral nutrition support (ENS) involves both the delivery of nutrients via feeding tubes and the provision of specialised oral nutritional supplements. ENS is indicated in a patient with at least a partially functioning digestive tract when oral intake is inadequate or intake of normal food is inappropriate to meet the patients' needs. The aim of this comment by the Committee on Nutrition of the European Society for Pediatric Gastroenterology, Hepatology, and Nutrition is to provide a clinical practice guide to ENS, based on the available evidence and the clinical expertise of the authors. Statements and recommendations are presented, and future research needs highlighted, with a particular emphasis placed on a practical approach to ENS.Among the wide array of enteral formulations, standard polymeric feeds based on cow's-milk protein with fibre and age adapted for energy and nutrient content are suitable for most paediatric patients. Whenever possible, intragastric is preferred to postpyloric delivery of nutrients, and intermittent feeding is preferred to continuous feeding because it is more physiological. An anticipated duration of enteral nutrition (EN) exceeding 4 to 6 weeks is an indication for gastrostomy or enterostomy. Among the various gastrostomy techniques available, percutaneous endoscopic gastrostomy is currently the first option. In general, both patients and caregivers express satisfaction with this procedure, although it is associated with a number of well-recognised complications. We strongly recommend the development and application of procedural protocols that include scrupulous attention to hygiene, as well as regular monitoring by a multidisciplinary nutrition support team to minimise the risk of EN-associated complications.

Endoscopic placement of a novel feeding tube

BACKGROUND

Complications of blind feeding tube (FT) placement include pneumothorax, pneumonia, empyema, and death. A safe and effective method of FT placement is desired. The Davis FT is a novel device that detachably couples to an ultrathin transnasal gastroscope. The objective of this study was to evaluate the safety and efficacy of Davis FT placement.

METHODS

Fifty consecutive patients requiring transpyloric enteral tube feeding underwent placement of the Davis FT. Placement efficacy was evaluated with postplacement radiographs. Patient demographics, route of tube placement, use of sedation, and complications were abstracted.

RESULTS

The Davis FT was placed successfully in 50 patients. The mean age of the cohort was 52 (+/- 18) years. Sixty-two percent (31/50) were men. The success rate of nonpulmonary placement was 100% (50/50), and the postpyloric success rate was 96% (48/50). IV sedation was used in 72% (36/50) of placements. Eighty-six percent (43/50) of tubes were placed transnasally. The majority (62%) of esophagogastroduodenoscopies and Davis FT placements was performed by a pulmonologist. Forty-four percent (22/50) of patients had an endotracheal tube, 20% (10/50) had a tracheotomy, and 36% (18/50) had no breathing tube at the time of Davis FT placement. There were no complications.

CONCLUSIONS

Transpyloric placement of the Davis FT is safe (100%) and effective (96%). The tube can be placed transorally or transnasally with or without sedation. The data suggest that postplacement radiographs are not necessary to confirm placement. Pulmonologists were successful in performing EGD and Davis FT placement.

Methods for determining the correct nasogastric tube placement after insertion: a meta-analysis

BACKGROUND

Nasogastric tubes are frequently used in the clinical setting for the management of patients who require decompression of the gastrointestinal tract, diagnosis and assessment, nutritional support and medication administration. A variety of bedside methods have been used either individually or in combination to assess NG tube placement.

OBJECTIVES

The objective of this review is to present the best available evidence to support decisions pertaining to methods for determining the correct nasogastric tube placement after insertion.

SEARCH STRATEGY

A literature search was performed using the following databases MEDLINE (1950 to Sept 2008), CINAHL (1982 to Sept 2008), EMBASE (1980 to Sept 2008) and All EBM Reviews (up to 3rd Quarter 2008). Chinese databases searched included WanFang Data (1998 to Sept 2008), China Journal Net (1994 to Sept 2008), Chinese Medical Current Contents (1994 to Sept 2008), Index to Chinese Periodical Literature (1970 to Sept 2008), and the Chinese Biomedical Literature Database (1980 to Sept 2008). In addition the reference lists of relevant trials and conference proceedings were also scrutinised. Investigators were contacted to elicit further information.

SELECTION CRITERIA

Clinical trials, prospective studies, observational studies, case reports, and evaluation studies assessing the diagnostic accuracy of methods for determining the correct placement of nasogastric tube after insertion were considered for inclusion in the meta-analysis.

DATA COLLECTION AND ANALYSIS

Eligibility of the trials for inclusion in the review, details of eligible trials and the methodological quality of the trials were assessed independently by two reviewers. Since not all trials reported true positive, true negative, false positive and false negative rates, these rates were calculated based on the data in the published papers. The two by two tables were reconstructed for each study, and sensitivity, specificity, positive predictive value, negative predictive value, positive likelihood ratio and negative likelihood ratio were calculated for each study. Diagnostic studies presenting insufficient data for construction of a two by two table were excluded from statistical analysis, but were included in the narrative part of the review.

MAIN RESULTS

Twenty-six trials were included in this meta-analysis: three trials investigated the effectiveness of colorimetric capnometry in detecting inadvertent airway intubation; three trials reported the use of capnography to verify tube placement in airway and to differentiate between respiratory and GI tube placement; one trial compared the use of a portable capnograph with a disposable colorimetric CO2 indicator in detecting inadvertent respiratory intubation. There were nine trials made use of a variety of cut-off points based on the biochemical measurement parameters of feeding tube aspirates (pH, bilirubin, pepsin and trypsin) in differentiating gastric from respiratory and intestinal placement of feeding tubes; one trial evaluated the accuracy of six pH test-strips. There were nine trials investigated the effectiveness of using various methods to differentiate between respiratory and GI feeding tube placement which included the use of: spring gauge pressure manometer, magnetic detection, sonography, auscultation and visual inspection of aspirates.

AUTHORS' CONCLUSION

The limited evidence obtained from the meta-analysis does not provide a substantial base for the development of practice guidelines. However, based on the trials undertaken to date, there is strong evidence to support the use of capnography or colorimetric capnometry for identification of feeding tube placement in mechanically ventilated patients. Until stronger evidence becomes available practice related to the diagnostic tests used within the clinical setting will continue to be dictated by local preferences and cost factors.

Confirming nasogastric tube position in the emergency department: pH testing is reliable

OBJECTIVE

The aim of this study was to determine whether pH testing is an accurate method of confirming nasogastric tube (NGT) position in children with and without gastroenteritis in the emergency department.

METHODOLOGY

A prospective observational study of NGT insertions was conducted at a tertiary pediatric emergency department, during a 9-month period in 2006. We evaluated methods of NGT position confirmation, pH of nasogastric aspirates from patients with and without gastroenteritis, and adverse events.

RESULTS

A total of 404 patients were enrolled. For 393 patients (97.3%), NGT aspirates could be obtained to assess pH. Of these patients, 294 (74.8%) had a diagnosis of gastroenteritis and 99 (25.2%) did not. There was no difference in median pH between the patients with gastroenteritis (pH, 2; interquartile range, 2-4) and those without gastroenteritis (pH, 2; interquartile range, 2-4; P = 0.09). Overall, 341 patients (86.8%) had a pH of 4 or lower. The patients with gastroenteritis were more likely to have a pH of 4 or lower than the patients without gastroenteritis (P = 0.018). Tube position was confirmed by pH alone in 332 patients (84.5%). Nine (2.6%) of the 341 patients with a pH of 4 or lower also had radiography (7 for causes other than confirmation of NGT position) indicating correct placement of all NGTs. Fifty-two patients (13.2%) had a pH higher than 4, and 18 (34%) of these had the tube position confirmed by radiography, of which 3 had tubes misplaced in the distal esophagus. Irrespective of pH level, there were no respiratory placements clinically or by radiography. Overall, 22 patients (5.6% 95% CI 3.5%-8.3%) required more than 1 attempt for NGT insertion. There were 13 minor adverse events (3.3% 95% CI 1.8%-5.6%) and no major adverse events.

CONCLUSIONS

Testing of gastric pH is a reliable way of confirming NGT position when the pH is 4 or lower. When the pH is higher than 4, a radiograph may be necessary.

Preventing aspiration in older adults with dysphagia

Dysphagia, the impairment of any part of the swallowing process, increases the risk of aspiration. Dysphagia and aspiration are associated with the development of aspiration pneumonia. While some changes in swallowing may be a natural result of aging, dysphagia is especially prevalent among older adults with neurologic impairment or dementia, leading to an increased risk of aspiration and aspiration pneumonia. This article discusses best practices for assessment and prevention of aspiration among older adults who are being hand-fed or fed by tube. To view an accompanying online video, go to http://links.lww.com/A226.

Exploring the role of organizational policies and procedures in promoting research utilization in registered nurses

BACKGROUND

Policies and procedures (P&Ps) have been suggested as one possible strategy for moving research evidence into practice among nursing staff in hospitals. Research in the area of P&Ps is limited, however. This paper explores: 1) nurses' use of eight specific research-based practices (RBPs) and RBP overall, 2) nurses' use and understanding of P&Ps, and 3) the role of P&Ps in promoting research utilization.

METHODS

Staff nurses from the eight health regions governing acute care services across the Canadian province of Newfoundland and Labrador completed an anonymous questionnaire regarding their use of eight RBPs and associated P&Ps. Data were also obtained from authorities in six of the eight regions about existing relevant P&Ps. We used descriptive statistics and multivariate regression analysis to assess the relationship between key independent variables and self-reported use of RBP.

RESULTS

Use of the eight RBPs ranged from 7.8% to 88.6%, depending on the practice. Nurses ranked P&P manuals as their number one source of practice knowledge. Most respondents (84.8%) reported that the main reason they consult the P&P manual is to confirm they are practicing according to agency rules. Multivariate regression analysis identified three significant predictors of being a user versus non-user of RBP overall: awareness, awareness by regular use, and persuasion. Six significant predictors of being a consistent versus less consistent user of RBP overall were also identified: perception of P&P existence, unit, nursing experience, personal experience as a source of practice knowledge, number of existing research-based P&Ps, and lack of time as a barrier to consulting P&P manuals.

CONCLUSION

Findings suggest that nurses use P&Ps to guide their practice. However, the mere existence of P&Ps is not sufficient to translate research into nursing practice. Individual and organizational factors related to nurses' understanding and use of P&Ps also play key roles. Thus, moving research evidence into practice will require careful interplay between the organization and the individual. P&Ps may be the interface through which this occurs.

Mechanisms of acid and base secretion by the airway epithelium

One of the main functions of the airway epithelium is to inactivate and remove infectious particles from inhaled air and thereby prevent infection of the distal lung. This function is achieved by mucociliary and cough clearance and by antimicrobial factors present in the airway surface liquid (ASL). There are indications that airway defenses are affected by the pH of the ASL and historically, acidification of the airway surfaces has been suggested as a measure of airway disease. However, even in health, the ASL is slightly acidic, and this acidity might be part of normal airway defense. Only recently research has focused on the mechanisms responsible for acid and base secretion into the ASL. Advances resulted from research into the airway disease associated with cystic fibrosis (CF) after it was found that the CFTR Cl(-) channel conducts HCO (3) (-) and, therefore, may contribute to ASL pH. However, the acidity of the ASL indicated parallel mechanisms for H(+) secretion. Recent investigations identified several H(+) transporters in the apical membrane of the airway epithelium. These include H(+) channels and ATP-driven H(+) pumps, including a non-gastric isoform of the H(+)-K(+) ATPase and a vacuolar-type H(+) ATPase. Current knowledge of acid and base transporters and their potential roles in airway mucosal pH regulation is reviewed here.

Important Facts About Intestinal Feeding Tube Placement

Enteral feeding is desirable when the gastrointestinal tract is functional because it allows better use of nutrients, is safer, and is more cost-effective than parenteral nutrition. Feeding through a gastric tube, however, is often not feasible in severely ill adults and children because of gastric paresis leading to recurrent episodes of gastroesophageal reflux with the risk of subsequent aspiration. Feeding into the small intestine (duodenum or jejunum) through a nasointestinal tube, therefore, is preferred. Unfortunately, no method of enteral feeding is risk free. This literature review addresses the following 10 topics: (a) the reasons why nasointestinal tube feeding is better tolerated by some patients, (b) candidates for nasointestinal tube feeding, (c) options for selecting nasointestinal tubes, (d) recommended methods for predicting the distance to insert nasointestinal tubes, (e) recommended methods for placing nasointestinal tubes, (f) how promotility medications work and whether they facilitate nasointestinal tube placement, (g) nasointestinal tube placement error rate, (h) methods of determining the internal location of nasointestinal tubes, (i) complications associated with nasointestinal tube use, and (j) other pertinent issues surrounding feeding through nasointestinal tubes. The available research evidence is summarized and recommendations for future work are suggested.

Normative Data for pH of Exhaled Breath Condensate

INTRODUCTION

Measurement of pH is one of the simplest and most technically validated biomarkers studied in exhaled breath condensate (EBC). The pH of EBC has been found to be lower than controls in many respiratory disorders. Published data from normal control subjects have been reasonably consistent, but the data sets are not large. This study was undertaken to establish normative EBC pH reference values.

PARTICIPANTS

Four hundred four healthy subjects of all ages were enrolled.

INTERVENTIONS

Each participant provided a single EBC sample using a disposable collector at modest temperature so that EBC was collected as a liquid.

MEASUREMENTS AND RESULTS

Samples of EBC were bubbled with argon gas to standardize for carbon dioxide, and pH was recorded with a calibrated and validated glass microelectrode on stabilization. The median EBC pH was 8.0 with interquartile (25 to 75%) range of 7.8 to 8.1. There were no differences based on age, sex, or race. The distribution is skewed, with 6.4% of EBC samples having a pH range < 7.4.

CONCLUSIONS

An extensive normal data set now exists that reveals EBC pH is maintained in a modestly alkaline and tight range in subjects who consider themselves healthy.

Confirmation of nasogastric tube position by pH testing

INTRODUCTION

In 2004, the Medicines and Healthcare products Regulatory Agency (MHRA) advised that nasogastric (NG) tube position should be confirmed using pH strips or paper. However, gastric pH is raised by the use of H2-blockers and proton-pump inhibitors (PPIs) potentially producing false negative pH tests resulting in delayed feeding. In addition, colorimetric differentiation using pH strips may be more prone to bias and inaccuracy than direct pH measurements largely used to establish the threshold.

METHOD

To quantify this problem a 1 day survey of all the patients requiring NG and nasointestinal (NI) feeding was undertaken, to establish the numbers of patients receiving H2-Blockers or PPIs, with or without a safe swallow and the methods currently being used to confirm tube positioning. A second observational study was performed to establish the accuracy of six pH strips available to NHS trusts against four unlabelled pH solutions.

RESULTS

Forty-two per cent of patients receiving NG feeding were on H2-blockers or PPIs, including 13% who had a safe swallow for acidic drinks that could be subsequently aspirated to confirm position. In the second study 'testers' correctly identified pH's 3, 4, 5 and 6 with Mackery-Nagel 0-6, BDH 0-6 and 0-14 strips but overestimated pH 4 as pH 5 with Johnson 0-11 paper, underestimated pH 6 as pH 5 with Pehanon 0-12 paper and with Litmus classified pH 3-5 as acid (all), but half also classified pH 6 as acid.

CONCLUSION

Theoretically 29% of NG tube positions could not be confirmed by pH testing because of the usage of PPIs or H2-blockers and lack of swallow. Some pH strips are either inaccurate or their result misinterpreted by staff. Large surveys and trials of the actual efficacy and accuracy of pH testing are required.

Sonography as an alternative to radiography for nasogastric feeding tube location

OBJECTIVE

To evaluate bedside sonographic confirmation of weighted-tip nasogastric feeding tube position, by comparison to radiography.

DESIGN AND SETTING

Single-center, double-blind prospective study in a 14-bed medical intensive care unit (ICU) in a 780-bed teaching hospital.

PATIENTS

Thirty-three ICU patients undergoing nasogastric tube insertion for enteral feeding.

INTERVENTIONS

The tip of the nasogastric tube was located both by sonography and standard radiography.

MEASUREMENTS AND RESULTS

The accuracy and procedure times of sonography and radiography for nasogastric tube tip location were compared during 35 procedures in 33 patients. The nasogastric tube tip was visualized by sonography in 34 of 35 procedures (sensitivity 97%) and by radiography in all procedures. The median length of the entire procedure was 24 min and 180 min with sonography and radiography, respectively.

CONCLUSIONS

Bedside sonography performed by nonradiologists is a sensitive method for confirming the position of weighted-tip feeding nasogastric feeding tubes. It is more rapid than conventional radiography and can easily be taught to ICU physicians. Conventional radiography could be reserved for cases in which sonography is inconclusive.