Photoplethysmographic (PPG) signals recorded from the human oesophagus

Background and Goal of study: Although a major advance in clinical monitoring, pulse oximetry may fail when peripheral perfusion is poor (1). Measurement of arterial oxygen saturation (SpO2) at the cricopharyngeus has been attempted in anaesthetised patients, but readings varied with the orientation of the probe (2), and suffered from signal failure (3). We have recorded PPG signals from the lower oesophagus to determine optimal recording depth and signal qualit

Design and evaluation of a new electro-optical system for monitoring oesophageal photoplethysmographs

When peripheral perfusion is poor and barely pulsatile, arterial blood oxygen saturation (SpO2) readings from commercial pulse oximeter probes placed peripherally can become unreliable or cease. The human oesophagus has been investigated as a potential measurement site on the hypothesis that perfusion may be better preserved at this central site. A new reflectance photoplethysmographic (PPG) optical sensor and a signal processing and data acquisition system have been developed. Oesophageal PPG signals were obtained from 16 anaesthetised patients and displayed on a laptop computer. PPGs with high signal-to-noise ratio at two wavelengths (red and infrared) and five oesophageal depths were recorded. Signals from the middle oesophagus were larger than those from the upper and deep oesophagus

Can the Human Oesophagus give adequate PPG Signals for Pulse Oximetry?

Pulse oximeter probes placed peripherally may fail to give accurate values of arterial blood oxygen saturation (SpO2) when peripheral perfusion is poor. Since central blood flow may be preferentially preserved, the oesophagus was investigated as an alternative monitoring site. An oesophageal photoplethysmographic (PPG) probe comprising miniature surface-mount optoelectronic devices and operating at 880nm and 655nm was constructed to fit into a disposable transparent stomach tube (20 French gauge). An electrically isolated signal processing system was developed. The output was digitised and further analysed by a virtual instrument implemented in Labview on a laptop computer. Infrared and red AC and DC PPG traces together with an ECG trace were obtained simultaneously and displayed on the laptop screen. We studied 20 healthy (ASA 1 or 2) adults who were scheduled for surgery under general anaesthesia, for which tracheal intubation would be required. The PPG probe was inserted into the mid-oesophagus at laryngoscopy. An identical probe was placed on a finger, and signals from each were processed and displayed on a laptop computer, using the same gain characteristics for each channel. In 13 further patients, we compared the amplitudes of the PPG signals at five different depths in the oesophagus (30, 25, 20, 15 cm, measured from the upper incisor teeth) to determine an optimal position for reliable SpO2 monitoring. In all patients, we were able to record PPGs with good signal-to-noise ratio from the length of the oesophagus. The amplitudes of the oesophageal PPGs are on average approximately three times larger than those obtained simultaneously from a finger, although there is considerable variability. The PPG signals in the mid to lower region of the oesophagus on average had larger amplitudes at both red and infrared wavelengths than the PPGs recorded in the upper oesophagus. The red and infrared wavelengths used are suitable for pulse oximetry, and these results justify further studies to evaluate the lower oesophagus as a potential site for blood oxygen saturation monitoring in patients with poor peripheral perfusion

Development of Fecal Coliform TMDL Protocols for Bass and Cinder Creeks on Kiawah Island

2008 S.C. Water Resources Conference - Addressing Water Challenges Facing the State and Regio

A system for investigating oesophageal photoplethysmographic signals in anaesthetised patients

The monitoring of arterial blood oxygen saturation in patients with compromised peripheral perfusion is often difficult, because conventional non-invasive techniques such as pulse oximetry (SpO2) can fail. Poor peripheral circulation commonly occurs after major surgery including cardiopulmonary bypass. The difficulties in these clinical situations might be overcome if the sensor were to monitor a better perfused central part of the body such as the oesophagus. A new oesophageal photoplethysmographic (PPG) probe and an isolated processing system have been developed to investigate the pulsatile signals of anaesthetised adult patients undergoing routine surgery. Measurements were made in the middle third of the oesophagus, 25 cm to 30 cm from the upper incisors. The AC PPG signals are sampled by a data acquisition system connected to a laptop computer. The signals recorded correspond to infrared and red AC PPGs from the middle third oesophagus and the finger. Preliminary results from 20 patients show that good quality AC PPG signals can be measured in the human oesophagus. The ratio of the oesophageal to finger AC PPG amplitudes was calculated for the infrared and red wavelengths for each patient. The mean (+/- standard deviation) of this ratio was 2.9 +/- 2.1 (n = 19) for the infrared wavelength and 3.1 +/- 2.4 (n = 16) for the red wavelength. The red and infrared wavelengths used are appropriate for pulse oximetry and this investigation indicates that the mid-oesophagus may be a suitable site for the reliable monitoring of SpO2 in patients with poor peripheral perfusion

Standalone vertex finding in the ATLAS muon spectrometer

A dedicated reconstruction algorithm to find decay vertices in the ATLAS muon spectrometer is presented. The algorithm searches the region just upstream of or inside the muon spectrometer volume for multi-particle vertices that originate from the decay of particles with long decay paths. The performance of the algorithm is evaluated using both a sample of simulated Higgs boson events, in which the Higgs boson decays to long-lived neutral particles that in turn decay to bbar b final states, and pp collision data at √s = 7 TeV collected with the ATLAS detector at the LHC during 2011

Measurements of Higgs boson production and couplings in diboson final states with the ATLAS detector at the LHC

Measurements are presented of production properties and couplings of the recently discovered Higgs boson using the decays into boson pairs, H →γ γ, H → Z Z∗ →4l and H →W W∗ →lνlν. The results are based on the complete pp collision data sample recorded by the ATLAS experiment at the CERN Large Hadron Collider at centre-of-mass energies of √s = 7 TeV and √s = 8 TeV, corresponding to an integrated luminosity of about 25 fb−1. Evidence for Higgs boson production through vector-boson fusion is reported. Results of combined fits probing Higgs boson couplings to fermions and bosons, as well as anomalous contributions to loop-induced production and decay modes, are presented. All measurements are consistent with expectations for the Standard Model Higgs boson

Measurement of the top quark pair cross section with ATLAS in pp collisions at √s=7 TeV using final states with an electron or a muon and a hadronically decaying τ lepton

A measurement of the cross section of top quark pair production in proton-proton collisions recorded with the ATLAS detector at the Large Hadron Collider at a centre-of-mass energy of 7 TeV is reported. The data sample used corresponds to an integrated luminosity of 2.05 fb -1. Events with an isolated electron or muon and a τ lepton decaying hadronically are used. In addition, a large missing transverse momentum and two or more energetic jets are required. At least one of the jets must be identified as originating from a b quark. The measured cross section, σtt-=186±13(stat.)±20(syst.)±7(lumi.) pb, is in good agreement with the Standard Model prediction

Measurement of the top quark-pair production cross section with ATLAS in pp collisions at \sqrt{s}=7\TeV

A measurement of the production cross-section for top quark pairs(\ttbar) in $pp$ collisions at \sqrt{s}=7 \TeV is presented using data recorded with the ATLAS detector at the Large Hadron Collider. Events are selected in two different topologies: single lepton (electron $e$ or muon $\mu$) with large missing transverse energy and at least four jets, and dilepton ($ee$, $\mu\mu$ or $e\mu$) with large missing transverse energy and at least two jets. In a data sample of 2.9 pb-1, 37 candidate events are observed in the single-lepton topology and 9 events in the dilepton topology. The corresponding expected backgrounds from non-\ttbar Standard Model processes are estimated using data-driven methods and determined to be $12.2 \pm 3.9$ events and $2.5 \pm 0.6$ events, respectively. The kinematic properties of the selected events are consistent with SM \ttbar production. The inclusive top quark pair production cross-section is measured to be \sigmattbar=145 \pm 31 ^{+42}_{-27} pb where the first uncertainty is statistical and the second systematic. The measurement agrees with perturbative QCD calculations.Comment: 30 pages plus author list (50 pages total), 9 figures, 11 tables, CERN-PH number and final journal adde

Testing of an oral dosing technique for double-crested cormorants, \u3ci\u3ePhalacocorax auritus\u3c/i\u3e, laughing gulls, \u3ci\u3eLeucophaeus atricilla\u3c/i\u3e, homing pigeons, \u3ci\u3eColumba livia\u3c/i\u3e, and western sandpipers, \u3ci\u3eCalidris mauri\u3c/i\u3e, with artificially weather MC252 oil

Scoping studies were designed to determine if double-crested cormorants (Phalacocorax auritus), laughing gulls (Leucophaues atricilla), homing pigeons (Columba livia) and western sandpipers (Calidris mauri) that were gavaged with a mixture of artificially weathered MC252 oil and food for either a single day or 4–5 consecutive days showed signs of oil toxicity. Where volume allowed, samples were collected for hematology, plasma protein electrophoresis, clinical chemistry and electrolytes, oxidative stress and organ weigh changes. Double-crested cormorants, laughing gulls and western sandpipers all excreted oil within 30 min of dose, while pigeons regurgitated within less than one hour of dosing. There were species differences in the effectiveness of the dosing technique, with double-crested cormorants having the greatest number of responsive endpoints at the completion of the trial. Statistically significant changes in packed cell volume, white cell counts, alkaline phosphatase, alanine aminotransferase, creatine phosphokinase, gamma glutamyl transferase, uric acid, chloride, sodium, potassium, calcium, total glutathione, glutathione disulfide, reduced glutathione, spleen and liver weights were measured in double-crested cormorants. Homing pigeons had statistically significant changes in creatine phosphokinase, total glutathione, glutathione disulfide, reduced glutathione and Trolox equivalents. Laughing gulls exhibited statistically significant decreases in spleen and kidney weight, and no changes were observed in any measurement endpoints tested in western sandpipers