Deirdre Toher

Infrared spectroscopic studies of cells and tissues: triple helix proteins as a potential biomarker for tumors.

In this work, the infrared (IR) spectra of living neural cells in suspension, native brain tissue, and native brain tumor tissue were investigated. Methods were developed to overcome the strong IR signal of liquid water so that the signal from the cellular biochemicals could be seen. Measurements could be performed during surgeries, within minutes after resection. Comparison between normal tissue, different cell lineages in suspension, and tumors allowed preliminary assignments of IR bands to be made. The most dramatic difference between tissues and cells was found to be in weaker IR absorbances usually assigned to the triple helix of collagens. Triple helix domains are common in larger structural proteins, and are typically found in the extracellular matrix (ECM) of tissues. An algorithm to correct offsets and calculate the band heights and positions of these bands was developed, so the variance between identical measurements could be assessed. The initial results indicate the triple helix signal is surprisingly consistent between different individuals, and is altered in tumor tissues. Taken together, these preliminary investigations indicate this triple helix signal may be a reliable biomarker for a tumor-like microenvironment. Thus, this signal has potential to aid in the intra-operational delineation of brain tumor borders.

Nasogastric tube depth: the ‘NEX’ guideline is incorrect

Misplacing 17-23% of nasogastric (NG) tubes above the stomach ( Rollins et al, 2012 ; Rayner, 2013 ) represents a serious risk in terms of aspiration, further invasive (tube) procedures, irradiation from failed X-ray confirmation, delay to feed and medication. One causal factor is that in the National Patient Safety Agency (NPSA) guidance to place a tube, length is measured from nose to ear to xiphisternum (NEX) ( NSPA, 2011 ); NEX is incorrect because it only approximates the nose to gastro-oesophageal junction (GOJ) distance and is therefore too short. To overcome this and because the xiphisternum is more difficult to locate, local policy is to measure in the opposite direction; xiphisternum to ear to nose (XEN), then add 10 cm. The authors determined whether external body measurements can be used to estimate the NG tube length to safely reach the gastric body. This involved testing the statistical association of body length, age, sex and XEN in consecutive critically ill patients against internal anatomical landmarks determined from an electromagnetic (EM) trace of the tube path. XEN averaged 50 cm in 71 critically ill patients aged 53±20 years. Tube marking and the EM trace were used to determine mean insertion distances at pre-gastro-oesophageal junction (GOJ) (48 cm), where the tube first turns left towards the stomach and becomes shallow on the trace; gastric body (62 cm), where the tube reaches the left-most part of the stomach; and gastric antrum (73 cm) at the midline on the EM trace. Using body length, age, sex and XEN in a linear regression model, only 25% of variability was predicted, showing that external measurements cannot reliably predict the length of tube required to reach the stomach. A tube length of XEN (or NEX) is too short to guarantee gastric placement and is unsafe. XEN+10 cm or more complex measurements will reach the gastric body (mid-stomach) in most patients, but because of wide variation, external measurements often fail to predict a safe distance. Only the EM trace or possibly direct vision can show in real time whether the tip has safely reached the gastric body.

Semi-supervised linear discriminant analysis

Fishers linear discriminant analysis is one of the most commonly used and studied classification methods in chemometrics. The method finds a projection of multivariate data into a lower dimensional space so that the groups in the data are well separated. The resulting projected values are subsequently used to classify unlabeled observations into the groups.

Time to Initial Debridement and wound Excision (TIDE) in severe open tibial fractures and related clinical outcome: A multi-centre study

BACKGROUND Recent national (NICE) guidelines in England recommend that initial debridement and wound excision of open tibial fractures take place within 12 h of the time of injury, a change from the previous target of 24 h. This study aims to assess the effect of timing of the initial debridement and wound excision on major infective complications, the impact of the new guidance, and the feasibility of adhering to the 12 h target within the infrastructure currently existing in four major trauma centres in England. METHODS A retrospective review was performed of Gustilo-Anderson grade 3B open tibial fractures presenting acutely to four Major Trauma Centres (MTCs) in England with co-located plastic surgery services over a ten-month period. The incidence of deep infective complications was compared between patients who underwent initial surgery according to the new NICE guidance and those who did not. Patients warranting emergency surgery for severely contaminated injury, concomitant life-threatening injury and neurovascular compromise were excluded. Multi-variable logistic regression analysis was performed to assess the effect of timing of surgical debridement on development of deep infective complications. RESULTS 112 patients with 116 fractures were included. Six fractures (5.2%) developed deep infective complications. 38% (n = 44) underwent primary debridement within 12 h and 90% within 24 h. There was no significant difference in the incidence of major infective complications if debrided in less than or greater than 12 h (4.5% vs 5.6%, p = 1.00). Logistic regression found no significant relationship between timing of wound excision and development of deep infection. There was no significant decrease in mean time to debridement following introduction of new national guidance (13.6 vs 16.1 h) in these four MTCs. CONCLUSION Overall, the rate of deep infection in high energy open tibial fractures managed within the four major trauma centes is low. Achieving surgical debridement within 12 h is challenging within the current infrastructure, and it is unclear whether adhering to this target will significantly affect the incidence of severe infective complications. Debridement within 24 h appears achievable. If a 12-h target is to be met, it is vital to ensure dedicated orthoplastic capacity is adequately resourced.

Feeding tube securement in critical illness: implications for safety

Over 50 % of tape-secured feeding tubes are inadvertently lost. The impact of nasal bridle securement on nasogastric (NG) and nasointestinal (NI) tube loss, outcome and duration of use was determined from 1 October 2014 (NG) and 1 January 2010 respectively to 31 December 2017. From this and published data, the potential impact of nasal bridles on major complications was determined. Use of nasal bridles was independently associated with: an 80% reduction in inadvertent NI tube loss (odds ratio (OR): 95% confidence interval (CI): 0.2: 0.12-0.33, p<0.0001); increased duration of tube use (2.2 days, 95% CI: 0.7-3.7, p= 0.004); and an almost threefold likelihood of tubes being used until no longer needed (OR: 2.8, 95%CI: 1.9-4.3, p<0.0001). In a single-room intensive care unit, inadvertent tube loss dropped from 53% to 9% and tube redundancy (tube no longer required) rose from 20% to 64%. UK-wide bridle securement, by reducing premature tube loss and the need for replacement by 40%, could be associated with 1422 fewer pneumonias or pneumothoraces and 768 fewer deaths.