OC-087 PAIN AND INFLAMMATORY SIGNALLING IN TACKOMESH TRIAL PARTICIPANTS FOLLOWING ELECTIVE LAPAROSCOPIC INCISIONAL HERNIA REPAIR WITH INTRAPERITONEAL ONLAY MESH (IPOM) AND SPIRAL-TACK MESH FIXATION

Background

The aim of this study was to investigate for links between reported pain and inflammation within a sub-cohort of patients undergoing the IPOM plus repair through the measurement of serum/plasma levels of established inflammatory biomarkers in trial participants across 1-year follow up.

Methods

22 patients (12 Protack™ and 10 Reliatack™) within the TACKoMesh randomised controlled trial underwent serial blood sampling as part of their follow up. A panel of pro- and anti-inflammatory biomarkers were assayed using Luminex multiplex assays and ELISAs. Circulating biomarker concentrations were described and compared in the context of clinical and patient reported outcome data that was obtained within the trial.

Results

An increase in the serum concentration of pro- (IL-6 and CRP) and anti- (IL-10) inflammatory biomarkers was seen following IPOM plus repair. Serum IL-6 and CRP were significantly raised compared to baseline at post-operative Days 1, 6 and 30 (p < 0.05). Markers of onward signalling (Cortisol and TNF-alpha) and tissue repair (PDGF-AA and VEGF) showed a trend towards an elevation at similar timepoints (notably at post-op Day 6) but were not significantly different from baseline levels. There were no observed correlations between inflammatory signal and reported pain, treatment allocation within the trial, burden of implanted prosthetic material, or hernia recurrence.

Discussion

This study demonstrates the novel finding of a pro-inflammatory signal at post-operative Day 30 following the IPOM plus repair.

OC-088 CAN PROCOLLAGEN I AND PROCOLLAGEN III SERVE AS PREDICTIVE BIOMARKERS FOR INCISIONAL HERNIA RECURRENCE?

Background

The aim of this study was to determine the temporal evolution of extracellular matrix (ECM) remodelling and collagen biomarkers and their influence on incisional hernia recurrence after the IPOM plus repair.

Methods

A sub-cohort of patients (n=25) undergoing laparoscopic incisional hernia repair within the TACKoMesh randomised controlled trial were bled at serial timepoints up to 1-year following surgery. Serum/plasma concentration of biomarkers (Procollagen I, Procollagen III, Fibronectin, TGF-beta, MMP-2, MMP-9, TIMP-1, and TIMP-2) were quantified using ELISA and Luminex multiplex techniques. Data were described and compared between groups that developed and remained free from recurrence using R statistical software.

Results

Procollagen I was reduced relative to baseline on post-op Day 1 but increased at Days 6 and 30 (p<0.05). Procollagen III showed an elevation at Day 30. Lower levels of Procollagen I were detected at Day 0, Day 1 and Day 6 (p<0.05) and higher levels of Procollagen III at Day 0, Day 1, Day 6 and Day 30 (p<0.05) in patients with a recurrence.

Fibronectin was reduced at Day 1 and 6 (p<0.05) whilst TGF-β was increased at Day 30 (p<0.05). MMP-2 and its inhibitor TIMP-2 were reduced at post-operative Day 1 (p<0.05). MMP-9 was persistently higher than baseline (p<0.05) at all timepoints. TIMP-1 was elevated at post-op Days 6 and 30. No differences were found in the circulating concentrations of these biomarkers to predict a recurrence.

Conclusion

In patients that developed incisional hernia recurrence, low levels of Procollagen I and high levels of Procollagen III were detected.

OC-086 COMPARISON OF MESH-FIXATION TECHNIQUES IN LAPAROSCOPIC REPAIR OF INCISIONAL HERNIA, RELIATACK™ V PROTACK™ (TACKOMESH) NCT 03434301

Background

A study examining post-op pain, comparing permanent versus absorbable tack fixation devices, Protack™ versus Reliatack™, in IPOM plus repair.

Methods

TACKoMesh is a single-centre double-blind RCT conducted from 2017–2020 with 1-year follow up. Patients were randomised to either Protack™ (titanium tacks) or Reliatack™ (an articulating-arm with dissolvable tacks). Primary outcome was reported pain on activity at Day30. Secondary outcomes include recurrence and quality of life measures (SF-36 & Carolina Comfort Score).

Results

67 patients randomised: 36 with Protack™, 27 with Reliatack™, with 4 conversions. No significant difference in reported pain ‘on activity’ (post-operative Day 1, 6, 30 and 365). There was significantly reduced pain ‘at rest’ on Day1 with Reliatack™ (Protack™ 6 [4 to 9] vs Reliatack™ 4 [3 to 5], p = 0.020) and reduced pain at all other points with Reliatack™.

Operation (p = 0.001) & mesh-fixation (p = 0.001) times were longer, with more knots (p = 0.001) & tacks (p = 0.001) used with Reliatack™.

Entire cohort hernia recurrence, seroma formation, SSI & Clavien-Dindo Grade III-V complication were 8/63 (12.7%), 33/63 (52.4%), 7/63 (11.1%), and 12/63 (19.1%) respectively. There were no significant differences in these outcomes between the treatment groups. CCS showed improvement from post-op Day30 to 365. SF36 showed a reduction in baseline scores at post-op Day30.

Conclusion

There is no difference in reported pain ‘on activity’ following elective IPOM plus hernia repair when choosing either Protack™ or Reliatack™. There is a trend towards improved post-op pain ‘at rest’ with Reliatack™.

Accuracy of echocardiographic doppler measures of pulmonary hypertension compared with right heart catheterisation in a real world population referred to a specialist centre

Introduction

Right heart catheterisation (RHC) is the gold standard investigation for the diagnosis of pulmonary hypertension (PH). Transthoracic echocardiography (TTE) allows non-invasive screening for PH. This retrospective audit sought to compare the accuracy of non-invasive Doppler estimates of pulmonary artery pressure and pulmonary vascular resistance (PVR) compared to RHC in a real world cohort referred to a shared care PH centre.

Method

Between 2010 and 2019, a total of 310 patients referred for initial assessment of PH underwent TTE followed by RHC (mean interval 31±30 days). Bland-Altman analysis was used to retrospectively investigate the accuracy of Doppler estimates of Pulmonary Artery Systolic Pressure (PASP), mean Pulmonary Artery Pressure (mPAP), Right Atrial Pressure (RAP) and PVR compared to RHC. TTE mPAP estimates were made using the pulmonary regurgitation velocity at the beginning of diastole (mPAP = 4(PRVBD)2 + RAP). TTE PVR estimates were calculated using the equation 10(TRV / RVOTVTI) + 0.16.

Results

Seventy-six percent of the cohort (n=235) had RHC diagnosed PH (average mPAP 42.8±11.7mmHg). The peak tricuspid regurgitation velocity (TRV) was measurable in 87% (n=269) and was unmeasurable in 8% (n=19) of those with confirmed RHC PH. Ten percent (n=30) had inadequate IVC imaging. TTE estimates of PASP (n=239) had a good correlation to RHC PASP (rs=0.82, 95% CI 0.75–0.84). TTE PASP estimates tended to underestimate RHC PASP (bias −3.7±15.2mmHg) with wide limits of agreement (95% limits of agreement −33.5–26.1mmHg) (figure 1); highlighting the imprecision of Doppler estimates alone. Only 44% of TTE PASP estimates were within 10mmHg of RHC PASP readings. Underestimation occurred more frequently accounting for 66% of inaccurate TTE PASP estimates. TTE RAP estimates (n=292) were weakly correlated to RHC RAP (rs=0.38, 95% CI 0.27–0.48).

TTE estimates of mPAP were only measurable in 81 patients and demonstrated moderate correlation to RHC mPAP (rs=0.58, 95% CI 0.4–0.71). TTE estimates tended to underestimate RHC mPAP (bias of −10±10.9mmHg) with wide limits of agreement (95% limits of agreement −31.3–11.3mmHg) (figure 1) suggesting poor accuracy and precision. Only 51% of TTE estimates were within 10mmHg of RHC mPAP with 93% of inaccuracies due to an underestimation of RHC mPAP. TTE PVR estimates (n=238) correlated well with RHC PVR measures (rs=0.68, 95% CI 0.6–0.74). However, Bland-Altman analysis (figure 2) demonstrated bias of −2.2±3.1WU with wide limits of agreement (95% limits of agreement −8.2–3.8WU), highlighting significant inaccuracy.

Conclusion

Doppler TTE measures to assess PH lack accuracy when compared with the gold standard RHC. Furthermore, the peak TRV was unmeasurable in 8% of those with confirmed RHC diagnosed PH. These findings further support the use of a multi parameter TTE approach for screening of PH.

Funding Acknowledgement

Type of funding sources: None.

Cortical hyperexcitability in migraine and aversion to patterns

BACKGROUND

Patients with migraine are averse to certain visual stimuli, such as flicker and striped patterns that evoke paroxysmal EEG activity in patients with photosensitive epilepsy. Migraineurs demonstrate a hyper-responsiveness to such stimuli, and there is debate as to whether the aversion and hyper-responsiveness are due to a hyperexcitability of the cortex similar to that in patients with photosensitive epilepsy. In these patients grating patterns with certain spatial characteristics can be epileptogenic, depending critically on their movement. If the contours of the grating drift continually, the grating is not epileptogenic, but if the contours are static or if their direction is repeatedly and rapidly reversed so as to vibrate, the grating then becomes highly epileptogenic.

METHODS

We compared aversion to vibrating, drifting and static gratings in migraineurs and controls. The contrast of each grating was gradually increased, but only until the participant felt discomfort, so as to obtain a contrast threshold for aversion with minimal exposure.

RESULTS

Migraineurs had lower thresholds than the control group, indicating greater aversion. For both groups the threshold was higher (aversion was lower) for static than for both types of moving gratings. The drifting gratings were more aversive than the vibrating gratings when both groups were combined.

CONCLUSION

The findings suggest that the aversion shown by migraineurs is not attributable to a cortical hyperexcitability similar to that in photosensitive epilepsy.

Binocular rivalry in migraine

Cortical hyperexcitability in migraine could arise from abnormally weak inhibition or from strengthened intracortical excitatory mechanisms. The present study employed binocular rivalry to differentiate between these possibilities. Rivalry between static oriented grating patterns was examined in migraine with aura (MA), migraine without aura (MoA) and headache-free control participants. A non-significant trend toward elevated mean dominance intervals (monocular percepts, in seconds) was seen in both migraine groups at all contrasts. Second, significant interocular differences in rivalry dominance durations were seen in the MoA group compared with controls; this difference also approached significance in the MA group. Finally, both MA and MoA exhibited significantly greater visual discomfort than the control group in the presence of both static stripes and flickering visual stimuli. The rivalry results provide no support for weakened intracortical inhibition in migraine. Optical or neural precortical differences in the eyes' input strengths paired with enhanced recurrent cortical excitation can explain these findings.

Evidence based guideline for the management of bronchiolitis

Bronchiolitis in infants and children is a common presentation in both the general practice and emergency department settings.

Evidence based guideline for the management of croup

Croup is a common presentation in both the general practice and hospital emergency department setting. The relatively recent introduction of steroid use in the management of croup has resulted in decreased hospital admissions and improved outcomes for children.

Guideline development process for the Health for Kids in the South East project

Health for Kids in the South East (HFK) was a project funded by the Victorian Government Department of Human Services, Hospital Admission Risk Program. The project aimed to improve health outcomes for children in southeast Melbourne (Victoria) by building partnerships between child health clinicians and implementing best practice.

Evidence based guideline for the management of diarrhoea with or without vomiting in children

Acute diarrhoea in children is a common presentation in both the general practice and hospital emergency department settings. Current practice focuses on the prevention and management of dehydration in young children. However, general practitioners may not be aware of recommendations against the use of routine investigation, antidiarrhoeals and antiemetics in children or recommendations regarding dietary advice.

The brain is hyperexcitable in migraine

Migraine is a very common disorder occurring in 20% of women and 6% of men. Central neuronal hyperexcitability is proposed to be the putative basis for the physiological disturbances in migraine. Since there are no consistent structural disturbances in migraine, physiological and psychophysical studies have provided insight into the underlying mechanisms. This is a review of the neurophysiological studies which have provided an insight to migraine pathogenesis supporting the theory of hyperexcitability.

Ocular motor measures in migraine with and without aura

The purpose of this study was to examine basic ocular motor function in individuals with migraine. We used an infrared eye-tracking system to measure horizontal smooth pursuit to a sinusoidal target, saccades to horizontal target displacements of 5-20 degrees , and the stability of fixation in 19 migraine without aura (MoA), 19 migraine with aura (MA) and 19 headache-free control (C) subjects. Eye movement measurements were made at two target displacement rates and against both homogeneous grey and patterned backgrounds. We found no statistically significant differences between migraine and control subjects in any of the eye movement parameters measured, but did find highly significant effects of both target speed and background pattern in all groups. Our results do not provide support for subclinical cerebellar impairment in migraineurs, and do provide evidence that previously described visual abnormalities in migraine are not artefacts of abnormal fixation or eye movements.

Photophysical properties of lumichromes in water

The photophysics of lumichrome, 1-methyllumichrome, and lumiflavin in water solutions have been investigated. Fluorescence lifetimes of 2.7 and 2.2 ns were observed for lumichrome and 1-methyllumichrome, respectively, the corresponding triplet state lifetimes of 17 and 18 micros have been obtained from the transient absorption spectra. Evidence for long lived species with absorption maxima near 450 nm and lifetimes of ca. 400 micros has been found in the transient absorption spectra of both lumichromes. Quantum yields for the sensitised production of singlet oxygen, phi(Delta), are 0.36 and 0.41 for lumichrome and 1-methyllumichrome, respectively, in D(2)O.

An inverse oblique effect in human vision

In the classic oblique effect contrast detection thresholds, orientation discrimination thresholds, and other psychophysical measures are found to be smallest for vertical or horizontal stimuli and significantly higher for stimuli near the +/-45 degrees obliques. Here we report a novel inverse oblique effect in which thresholds for detecting translational structure in random dot patterns [Glass, L. (1969). Moiré effect from random dots. Nature, 223, 578-580] are lowest for obliquely oriented structure and higher for either horizontal or vertical structure. Area summation experiments provide evidence that this results from larger pooling areas for oblique orientations in these patterns. The results can be explained quantitatively by a model for complex cells in which the final filtering stage in a filter-rectify-filter sequence is of significantly larger area for oblique orientations.

Perceived scintillation rate of migraine aura

OBJECTIVE

To measure the perceived rate of flicker (temporal frequency) observed during visual auras.

BACKGROUND

The flickering or scintillating quality of aura elements is a commonly described characteristic of visual migraine auras. Hypotheses about the neural mechanisms involved in aura have rarely taken this feature into account, perhaps because of a lack of quantitative data on this aspect of the aura. While a rate of 10 Hertz had been suggested in the literature, estimates have been speculative due to the difficulty of judging temporal frequencies subjectively.

METHODS

Eleven participants were given portable devices that contained an adjustable light-emitting diode with which to match the flickering of their auras. Observers were asked to make flicker matches at two time points so that rate change during aura progression could be analyzed.

RESULTS

Data were obtained for 36 aura episodes. The mean rate of flicker across individuals was 17.8 Hertz. Rates varied widely between individuals, but were more consistent across multiple episodes in the same observer. Rate of flicker did not appear to relate to aura side or type, or to individual characteristics such as migraine history. When episodes were analyzed for change in flicker rate over time, patterns of increase (n = 7), decrease (n = 4), and no change (n = 22) were all observed.

CONCLUSIONS

When measured with an objective task, aura scintillation rates were found to be somewhat higher than previous anecdotal observations had suggested. These data are discussed in the context of two competing hypotheses concerning the neural mechanism underlying the flicker percept during migraine aura.

An fMRI study of the selective activation of human extrastriate form vision areas by radial and concentric gratings

The ventral form vision pathway of the primate brain comprises a sequence of areas that include V1, V2, V4 and the inferior temporal cortex (IT) [1]. Although contour extraction in the V1 area and responses to complex images, such as faces, in the IT have been studied extensively, much less is known about shape extraction at intermediate cortical levels such as V4. Here, we used functional magnetic resonance imaging (fMRI) to demonstrate that the human V4 is more strongly activated by concentric and radial patterns than by conventional sinusoidal gratings. This is consistent with global pooling of local V1 orientations to extract concentric and radial shape information in V4. Furthermore, concentric patterns were found to be effective in activating the fusiform face area. These findings support recent psychophysical [2,3] and physiological [4,5] data indicating that analysis of concentric and radial structure represents an important aspect of processing at intermediate levels of form vision.

Perception of head orientation

There are two visual components to gaze: head orientation and orientation of the eyes relative to the head. This study explores the accuracy with which subjects can discriminate head orientation when the eyes are centered in the head. Discrimination thresholds averaged 1.9 degrees of head rotation for base head orientations of 0 degree and 15 degrees, but discrimination was markedly poorer around a 30 degrees head orientation. Results were independent of spatial frequency and size over a 4-fold range. Neither negative contrast nor head inversion affected discrimination. Experiments dissociating the internal features from head outline revealed the presence of two main cues to discrimination: deviation of the head profile from bilateral symmetry, and deviation of nose orientation from vertical. Simulations show that model V4 units revealed in previous experiments with Glass patterns can extract the relevant head orientation information. The data are consistent with neurological data indicating a selective loss of face recognition in prosopagnosia with spared gaze discrimination.

Methylene blue based protein solder for vascular anastomoses: an in vitro burst pressure study

BACKGROUND AND OBJECTIVE

Attempts at sutureless anastomoses have used protein-based solders containing chromophores [Oz et al., J Vasc Surg 1990;11:718; Poppas et al., J Urol 1998150:1052] to enhance the strength of laser anastomoses. Reports have described the use of indocyanine green [Oz et al., Surg Forum 1989;316.], fuschin, and fluorescein isothiocyanate as chromophores [Chuck et al. , Lasers Surg Med 1989;9:471; Vance et al., Lasers Med Sci 1988;3:219]. Methylene blue (MB) is a chromophore with absorption peaks in the 600-700 nm region whose use has not been reported in laser-assisted vascular anastomoses. Therefore, we set out to produce and characterise a MB-containing protein solder. The absorption and burst pressure characteristics have been investigated and described as well as a brief review of the chemical and biological properties of MB.

STUDY DESIGN/MATERIALS AND METHODS

The MB and porcine serum albumin (PSA)-based solder was produced and used to form end-to-end anastomoses in porcine splenic arteries. The solder was activated using a laser diode emitting at 670 nm. The burst pressures of the anastomoses were tested, and the results analysed as a function of MB concentration and absorption. In addition, the relationship between MB concentration and absorption was examined.

RESULTS

A dose-response relationship was found between the measured absorption of the solder and the burst pressure of the anastomoses formed. Burst pressures exceeding physiological levels were found. Changes in MB concentration revealed a marked negative deviation from Beer's law at 670 nm, owing to the monomer-dimer-trimer equilibria.

CONCLUSION

PSA with MB solder is able to form high-quality end-to-end anastomoses, with immediate burst pressure profiles similar to those previously described for sutured [Quigley et al., Microsurgery 1985;6:229], lasered [Quigley et al., Microsurgery 1985;6:229], and soldered anastomoses [Small et al., J Clin Laser Med Surg 1997;15:205]. The relationship between burst pressure strength and chromophore absorption is discussed.