Davey, Martin S.

Eberl, Matthias

Hall, Judith Elizabeth

Morgan, Matthew

Szakmany, Tamas

Shelley, B.

Tanner, O.

MacFie, A.

Kinsella, J.

Enlighten: Publications

Adjustment of extravascular lung water calculation for volume of resected lung does not improve construct validity in thoracic surgical patients

Phosphatidylcholines are integral part of pulmonary surfactant and cellular membranes and are synthesised de novo by two clinically distinct pathways. The molecular specificity of PC output varies between these pathways, where mono and di-unsaturated PC species are predominantly generated by the cytidine diphosphate choline (CDP-choline) pathway and polyunsaturated fatty acids (PUFA) by phosphatidylethanolamine-N-methyltransferase (PEMT) pathway. PUFA are capable of generating eicosanoids and have been long recognised as mediators of inflammation in various acute and chronic inflammatory conditions. ARDS is characterised by acute overwhelming inflammatory process and alterations in eicosanoid profile is a recognised feature. Consequently, this study was aimed to assess the molecular specificity of PEMT pathway in patients with severe ARDS. We recruited 10 patients with severe ARDS (Pa02/Fi02 &lt;100mmHg) and 10 healthy controls. Both groups were infused with a natural isotope of choline (methyl-D9-choline chloride). Blood samples were taken at serial time points until day 96 hours of recruitment. Samples were centrifuged and the supernatant was lipid extracted. This was analysed in electro-spray ionisation mass spectrometry where the phosphocholine head group was identified by m/z+184 and subsequent m/z +187 for one and m/z+190 for two deuteriated methyl groups incorporations. From this, we estimated quantitative flux through PEMT pathway for all patients. At maximal synthesis, there was a significant reduction in total PC synthesis in patients via PEMT pathway (44% absolute reduction). This was coupled with reductions in the rate of total PC synthesis and absolute concentrations of PUFA based PC species in plasma. The molecular specificity of PC synthesis was similar for both groups, where PUFA species (E.g. 20:4 and 22:6) were highly selective through this pathway. In conclusion, there are significant alterations in PC synthetic pathways in patients with ARDS. Therapeutic modulation of PUFA may moderate inflammatory process in ARDS. Acknowledgement This study was supported by Southampton NIHR Respiratory Biomedical Research Unit and The National Institute of Academic Anaesthesia (NIAA), UK

Dushianthan, A.

Cusack, R.

Goss, V.

Postle, A. D.

Grocott, M. P. W.

Southampton (e-Prints Soton)

Altered phosphotidylcholine synthetic pathways in patients with acute respiratory distress syndrome

Belhaj, A.

Phillips, J. P.

Kyriacou, P. A.

Langford, R. M.

City Research Online

Belhaj, A., Phillips, J. P., Kyriacou, P. A. & Langford, R. M. (2013). Non-invasive optical estimation of local venous oxygen saturation. British Journal of Anaesthesia, 110(5), 877P-878P. doi: 10.1093/bja/aes490 City Research OnlineOriginal citation: Belhaj, A., Phillips, J. P., Kyriacou, P. A. & Langford, R. M. (2013). Non-invasive optical estimation of local venous oxygen saturation. British Journal of Anaesthesia, 110(5), 877P-878P. doi: 10.1093/bja/aes490 Permanent City Research Online URL: http://openaccess.city.ac.uk/13362/ Copyright & reuseCity University London has developed City Research Online so that its users may access the research outputs of City University London's staff. Copyright © and Moral Rights for this paper are retained by the individual author(s) and/ or other copyright holders.  All material in City Research Online is checked for eligibility for copyright before being made available in the live archive. URLs from City Research Online may be freely distributed and linked to from other web pages. Versions of researchThe version in City Research Online may differ from the final published version. Users are advised to check the Permanent City Research Online URL above for the status of the paper.EnquiriesIf you have any enquiries about any aspect of City Research Online, or if you wish to make contact with the author(s) of this paper, please email the team at publications@city.ac.uk.Non-invasive optical estimation of local venous oxygen saturations A Belhaj*, JP Phillips*, P Kyriacou*, RM Langford  Biomedical Engineering Research Group, City University London.  Breathing causes variations in blood volume in the peripheral vascular bed, which are evident as respiratory-induced intensity variations (RIIV) on recorded photoplethysmography (PPG) signals during spontaneous and mechanical ventilation [1]. It has been suggested that suitable signal analysis of PPG signals in the respiratory frequency range can produce estimations of local venous oxygen saturation (SxvO2) [2,3]. Although saturations lower than those of arterial blood have been obtained from PPG analysis of oesophageal [2] and peripheral [4] measurements, these have not been validated by comparison with co-oximetry of venous blood. The aim of this study was to record PPG waveform effects and derived venous saturations during exaggerated inspiratory and expiratory airway pressures in volunteers.  Twelve healthy volunteers performed unforced breathing for one minute, followed by two minutes of forced breathing through a narrow tube. Airway pressure monitored from the mouthpiece was displayed in real time on a computer screen so that the volunteers could aim for recommended rate, rhythm and airway pressure values. At the end of the recording period, venous blood, sampled from the dorsum of the hand, was analysed in a co-oximeter (Radiometer ABL80). PPG-derived venous saturations were estimated using Fourier analysis of PPG signals in the respiratory frequency range.   Figure 1. Bland Altman Plot comparing PPG-derived and co-oximetry (co-ox) results The preliminary data (Figure 1) showed good correlation between PPG-derived SxvO2 and blood co-oximetry values (r = 0.805, mean difference = +2.3, n = 12). These results justify further studies in volunteers and mechanically ventilated patients.  References: 1. Shelley KH, Anesth Analg. 2007 Dec;105(6 Suppl):S31-6; 2. Walton ZD, Kyriacou PA, Silverman DG, Shelley KH,  J Clin Monit Comput. 2010 Aug;24(4): 295-303, 3. J. P. Phillips, P. A. Kyriacou, D. P. Jones, Curr Op Anesth, vol. 21, pp.779–783, 2008. 4. Thiele RH et al Anesth Analg 2011;112;1353-7. 

Non-invasive optical estimation of local venous oxygen saturation

Online Research @ Cardiff

Human gamma delta T cells in severe bacterial sepsis [Abstract]

Enlighten

Zaman, T.

Pal, P. K.

Zaman, T., Pal, P. K. & Kyriacou, P. A. (2013). Pilot investigation of DIEP free flap perfusion utilising a multi-wavelength non-invasive optical sensor. British Journal of Anaesthesia, 110(5), pp. 884-885. doi: 10.1093/bja/aes490 City Research OnlineOriginal citation: Zaman, T., Pal, P. K. & Kyriacou, P. A. (2013). Pilot investigation of DIEP free flap perfusion utilising a multi-wavelength non-invasive optical sensor. British Journal of Anaesthesia, 110(5), pp. 884-885. doi: 10.1093/bja/aes490 Permanent City Research Online URL: http://openaccess.city.ac.uk/3547/ Copyright & reuseCity University London has developed City Research Online so that its users may access the research outputs of City University London's staff. Copyright © and Moral Rights for this paper are retained by the individual author(s) and/ or other copyright holders.  All material in City Research Online is checked for eligibility for copyright before being made available in the live archive. URLs from City Research Online may be freely distributed and linked to from other web pages. Versions of researchThe version in City Research Online may differ from the final published version. Users are advised to check the Permanent City Research Online URL above for the status of the paper.EnquiriesIf you have any enquiries about any aspect of City Research Online, or if you wish to make contact with the author(s) of this paper, please email the team at publications@city.ac.uk.Title: Pilot investigation of DIEinvasive optical sensor.   T Zam1 City University, London; 2BroDeep Inferior Epigastric Perforaoption following mastectomy fooccur due to the insufficient bloof flap perfusion and early deteca need to develop a non-invasivedevice to assess flap perfusion p(PPG) sensor and battery powersignals and estimate free flap blointra and postoperatively 3.   The developed reflectance PPG ceramic chip surface mount LEDthe functionality of the PPG procarried out in ten patients undergresearch ethics committee approsensor was secured onto the expsignals acquisition was conductefirst two hours, every 30 minutehours. , with a diameter of 20mmDIEP flaps.  To evaluate the functionality of investigations were carried out iDIEP Flap. Local research ethicto the study. The sensor was secFree flap PPG signals acquisitiointervals in the first two hours, ethe next 12 hours.  P free flap perfusion utilising a multi-waan*1 SK Pal2 and PA Kyriacou1omfield Hospital, Chelmsford, Essextor (DIEP) free flaps are widely used as a recr breast cancer 1. During such cases partial tiod supply to the transplanted tissue site. Thertion of flap failure is a prerequisite to flap su, easy to use, reproducible and inexpensive mostoperatively. A multiwavelength photopleted processing system have been developed tood oxygen saturation continuously and non sensor consisted of two infrared, two red ands and a surface mount photodiode, as showncessing system, preliminary clinical investigaoing elective breast reconstruction with DIEval and patient consent was acquired prior toosed skin of the flap using surgical tape. Freed in the postoperative period at 15 minute ins for the following four hours and hourly for  in order to be accommodated on the exposethe PPG processing system, preliminary clinin ten patients undergoing elective breast recos committee approval and patient consent waured onto the exposed skin of the flap using sn was conducted in the postoperative period very 30 minutes for the following four hoursvelength non-onstruction ssue necrosis can efore monitoring rvival 2. There is onitoring hysmographic  investigate PPG invasively pre,  two green  in To evaluate tions were P Flap. Local  the study. The  flap PPG tervals in the the next 12 d part of the cal nstruction with s acquired prior urgical tape. at 15 minute  and hourly for An initial observation shows that the amplitude of the PPGs recorded in the postoperative period experience a reduction in amplitude after approximately 7 hours (Figure 2). Such observations need further investigation in order to identify the underlying reasons which cause such change. The utilisation of the green wavelength, with its strong absorption in melanin and haemoglobin and its short depth of penetration, may also provide some blood volumetric and flow activity of the free flap microcirculation 4-5.  This project was fully funded by EPSRC.  1) Thorne C, Grabb WC, Smith JW. Grabb and Smith's plastic surgery. 6th ed. 2007;  2) Serafin D, Shearin JC, Georgiade NG.  Plast Reconstr Surg 1977, 60: 233-41;  3) Zaman T, Kyriacou PA, Pal SK. Conf Proc IEEE Eng Med Biol Soc 2011,: 4006-9; 4) Futran ND, Stack BC, Jr., Hollenbeak C, Scharf JE. Arch Otolaryngol Head Neck Surg2000, 126: 659-62; 5) Maeda Y, Sekine M, Tamura T, Moriya A, Suzuki T, Kameyama K. Conf Proc IEEE Eng Med Biol Soc 2008, 2270-2. Argon combined with hypothermia protects against hypoxia-ischaemia induced brain damage in rat neonates Hailin Zhao*, Tracy Yushi Cui*, Daqing Ma Anaesthetics, Pain Medicine and Intensive Care, Department of Surgery and Cancer, Imperial College London, Chelsea and Westminster Hospital, London Hypoxic-ischaemic encephalopathy in newborns is a major cause of mortality and disability. Currently, there is no effective treatment apart from therapeutic hypothermia, which provides moderate neuroprotection (1-3). Argon, an abundant and inexpensive noble gas, has recently been demonstrated to be neuroprotective (4). In this study, the effects of argon in combination with hypothermia on neuronal cell death and neuroinflammation induced by hypoxic-ischaemic insult were investigated in a neonatal asphyxia model in rats.   Seven-day-old rats were subjected to unilateral common carotid artery ligation under 1-2% isoflurane anaesthesia (the total anaesthesia time < 10 min) followed by hypoxic (8% oxygen balanced with nitrogen) insult for  90 minutes in a purpose built chamber equipped with a water bath at 37°C. After 1 hour recovery with dame, they were exposed to 70% argon or nitrogen balanced with oxygen at 35°C, or nitrogen balanced with oxygen at 37°C for 2 hrs. Their brains were removed 24 hrs or 4 weeks after gas exposure for immunofluorescence staining and histological analysis respectively. Argon in combination with hypothermia decreased the fluorescence intensity of cleaved caspase-3 (an apoptotic marker) staining to 1.11 ± 0.06 arbitrary unit from 1.72±0.09 of the injurious controls (p < 0.01) in cortex and to 1.10 ± 0.04 from 1.72±0.07 of controls (p < 0.01) in hippocampus. NF-B, an inflammatory marker, was also reduced in cortex (1.16±0.06 vs 1.76±0.09 of injury controls, p < 0.001) and hippocampus (1.04 ± 0.06 vs1.92±0.31 of injury controls, p < 0.05) with the treatment.  Another neuroflammatory sign astrogliosis induced by hypoxia-ischaemia in hippocampus was significantly decreased in treated group. Argon combined with hypothermia reduced infarction size by 54% (p < 0.001) when compared to that of injurious controls. Hypothermia alone also conferred a protection but to much less extent when compared with the combined treatment.  Figure 1: Reflectance photoplethysmographic flap sensorFigure 2: The mean amplitude of ac PPGs  