Gary Mills | The University of Sheffield (original) (raw)

Papers by Gary Mills

Computer Methods and Programs in Biomedicine, Aug 1, 2010

c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 9 9 ( 2 0 1 0 ) 195... more c o m p u t e r m e t h o d s a n d p r o g r a m s i n b i o m e d i c i n e 9 9 ( 2 0 1 0 ) 195-207 Arterial blood gas Intensive care unit Shunt Dead space Neuro-fuzzy modelling ANFIS a b s t r a c t Arterial blood gas (ABG) analyses are essential for assessing the acid-base status and guiding the adjustment of mechanical ventilation in critically ill patients. Conventional ABG sampling requires repeated arterial punctures or the insertion of an arterial catheter causing pain, haemorrhage and thrombosis to the patients. Less invasive and non-invasive blood gas analysers, with a technology still in transition, have offered some promise in the recent years. SOPAVent (Simulation of Patients under Artificial Ventilation) is a five compartment blood gas model which captures the basic features of respiratory physiology and gas exchange in the human lungs. It uses ventilator settings and routinely monitored physiological parameters as inputs to produce steady-state estimates of the patient's ABG.

Proceedings of the Fifth Iasted International Conference Biomedical Engineering, Feb 14, 2007

... 35. [35] HJ Smit, ML Handoko, A. Vonk Noordegraaf, TJC Faes, PE Postmus, PM de Vries, and A. ... more ... 35. [35] HJ Smit, ML Handoko, A. Vonk Noordegraaf, TJC Faes, PE Postmus, PM de Vries, and A. Boonstra, "Electrical impedance tomography to ... 61. [61] JA Victorino, JB Borges, VN Okamoto, GF Matos, MR Tucci, MP Caramez, H. Tanaka, FS Sipmann, DC Santos, CS Barbas ...

Excessive noise is becoming a significant problem for intensive care units (ICUs). This paper fir... more Excessive noise is becoming a significant problem for intensive care units (ICUs). This paper first reviews the impact of noise on patients’ sleep in ICUs. Five previous studies have demonstrated such impacts, whereas six other studies have shown other factors to be more important. Staff conversation and alarms are generally regarded as the most disturbing noises for patients’ sleep in ICUs. Most research in this area has focused purely on noise level, but work has been very limited on the relationships between sleep quality and other acoustic parameters, including spectrum and reverberation time. Sound-absorbing treatment is a relatively effective noise reduction strategy, whereas sound masking appears to be the most effective technique for improving sleep. For future research, there should be close collaboration between medical researchers and acousticians.

The first objective of this study is to observe how the clinicians adjust ventilator settings in ... more The first objective of this study is to observe how the clinicians adjust ventilator settings in simulatedmechanically ventilated patients. This information was then used to construct the fuzzy rule-bases of a ventilatoradvisory system. A simulator of patients on artificial ventilation was developed using theMATLAB/SIMULINK environment based on a grey-box mathematical model of the human respiratory system.A graphic user interface (GUI) was designed to improve its usability. Eleven simulated patients wereconstructed. Each simulated patient consists of 7 to 44 tuned simulated events based on the data recorded in theintensive care unit (ICU) patient data management system (PDMS). Four ICU consultants were invited toparticipate in the simulation study. The fuzzy input partitions for the rule-bases were derived from theprobability distribution of the acceptable input values defined by the clinicians. The rules were derived aftercorrelation analysis of the simulation results and supplemen...

A model of the human respiratory system, the SOPAVent (Simulation of Patient under Artificial Ven... more A model of the human respiratory system, the SOPAVent (Simulation of Patient under Artificial Ventilation), is used in a model-based decision support system for intensive care ventilators. The model parameters, including the shunt and the deadspace, vary among patients and vary with time. In order to achieve adaptive control, the parameters have to be estimated on-line. The current method of parameter estimation is time-consuming and unreliable. An alternative method of parameter estimation was investigated in this study. The shunt was estimated using a linear regression model based on one of the hypoxaemia indices, the respiratory index, i.e. the ratio of the alveolar-arterial oxygen difference (P A-a O 2) to the arterial oxygen tension (PaO 2). Results of 117 sets of arterial and mixed venous blood gas measurement from 9 patients were retrieved from the Intensive Care Unit database. The ventilation settings and the patient's other measurements (cardiac output, body temperature...

Critical Care, 2015

Patients admitted to intensive care following surgery for faecal peritonitis present particular c... more Patients admitted to intensive care following surgery for faecal peritonitis present particular challenges in terms of clinical management and risk assessment. Collaborating surgical and intensive care teams need shared perspectives on prognosis. We aimed to determine the relationship between dynamic assessment of trends in selected variables and outcomes.

International journal of obstetric anesthesia, 1996

Occupational exposure to nitrous oxide may be increased in confined working environments where ve... more Occupational exposure to nitrous oxide may be increased in confined working environments where ventilation and scavenging are either ineffective or unavailable. This is particularly the case on the labour ward. To assess the exposure of midwives working on the labour ward, midwives were asked to wear personal nitrous oxide samplers during their shift periods. The nitrous oxide exposure during a total of 242 midwife shift periods was monitored in two hospitals. Seven (3%) of these midwife shifts demonstrated mean exposure levels of over 500 parts per million (ppm), the highest reaching 1638 ppm. Fifty-six (23%) had NZO levels over 100 ppm and 129 (53%) had levels above 25 ppm. During the 111 midwife shift periods where midwives did not work in a room where Entonox was in use, their mean exposure was 22 ppm (median 12 ppm), however in four of these midwife shift periods the mean exposure level exceeded 100 ppm. Chronic exposure to high levels of nitrous oxide which exceed the recently...

Continuing Education in Anaesthesia, Critical Care & Pain, 2010

This article describes the features of carcinoid tumours and the challenges involved in the anaes... more This article describes the features of carcinoid tumours and the challenges involved in the anaesthetic management and post-operative care of patients undergoing surgery for carcinoid.

2010 5th IEEE International Conference Intelligent Systems, 2010

One of the main advantages of Granular Computing and Fuzzy Logic is the transparency and interpre... more One of the main advantages of Granular Computing and Fuzzy Logic is the transparency and interpretability features that are available to the user. In this paper we present a systematic data granulation algorithm for the elicitation of Fuzzy rules and show how the granular data and relational information extracted during the data mining process can be translated into Fuzzy Logic statements with enhanced interpretability. Notions of granular cardinality, distribution and distance are used to apply linguistic hedges to two-sided Gaussian Fuzzy membership functions. The proposed methodology is applied to a biomedical dataset relating to Electrical Impedance Tomography (EIT) measurements of lung ventilation showing good agreement and interpretability between the captured knowledge and the theoretical and physiological expectations.

Spine, 1986

The role of liquid crystal thermography (LCT) in the investigation of nerve root compression due ... more The role of liquid crystal thermography (LCT) in the investigation of nerve root compression due to lumbosacral lateral spinal stenosis was evaluated using a quantitative analysis technique. In 28 healthy volunteers, normal lower limb dermatomal asymmetry was found to follow a Gaussian distribution, with a normal range of less than 1.0 degree for the lower limbs and less than 1.9 degrees for the feet. The results of LCT from a patient group were compared with those from other investigations, with the following results: clinical assessment (107 patients), 53% agreement; myelography (60 patients), 45% agreement; computerized tomography (35 patients), 46% agreement; electromyography (27 patients), 41% agreement; and surgical findings (19 patients), 53% agreement. Each method of investigation was compared against the surgeon's final overall assessment. Clinical assessment agreed in 76%, myelography in 71%, computerized tomography in 71%, and electromyography in 70%. However, agreement could be demonstrated in only 48% of cases using LCT; therefore, it would appear that LCT is by far the least reliable of these techniques in the diagnosis of nerve root compression.

Physiological Measurement, 2011

This paper describes a method for estimating lung density, air volume and changes in fluid conten... more This paper describes a method for estimating lung density, air volume and changes in fluid content from a non-invasive measurement of the electrical resistivity of the lungs. Resistivity in Ω m was found by fitting measured electrical impedance tomography (EIT) data to a finite difference model of the thorax. Lung density was determined by comparing the resistivity of the lungs, measured at a relatively high frequency, with values predicted from a published model of lung structure. Lung air volume can then be calculated if total lung weight is also known. Temporal changes in lung fluid content will produce proportional changes in lung density. The method was implemented on EIT data, collected using eight electrodes placed in a single plane around the thorax, from 46 adult male subjects and 36 adult female subjects. Mean lung densities (±SD) of 246 ± 67 and 239 ± 64 kg m(-3), respectively, were obtained. In seven adult male subjects estimates of 1.68 ± 0.30, 3.42 ± 0.49 and 4.40 ± 0.53 l in residual volume, functional residual capacity and vital capacity, respectively, were obtained. Sources of error are discussed. It is concluded that absolute differences in lung density of about 30% and changes over time of less than 30% should be detected using the current technology in normal subjects. These changes would result from approximately 300 ml increase in lung fluid. The method proposed could be used for non-invasive monitoring of total lung air and fluid content in normal subjects but needs to be assessed in patients with lung disease.

PAIN, 1984

myelography and objective surgical findings. Methods: 107 consecutive patients evaluated by a sin... more myelography and objective surgical findings. Methods: 107 consecutive patients evaluated by a single orthopaedic surgeon were referred for thermography, 60 also had myelography and 27 electromyography. 19 patients had surgery. The thermograms were assessed using a quantitative analysis technique to demonstrate corresponding dermatomal temperature difference in the lower limbs. A normal population sample (n=28) was also evaluated to determine the corresponding dermatomal tempature difference.From this data a positi;e result was recorded in the study group when the difference was)/1 0 c.

Journal of Hospital Infection, 2010

an appropriate antibiotics use improved the resistance rate of PA, it did not reduce the number o... more an appropriate antibiotics use improved the resistance rate of PA, it did not reduce the number of patients with PA and the total detectable amount of PA. Objective: To reduce detectable amount of PA and the number of patients infected with PA and MDRP through a complete hospital environment maintenance. Method: The condition of the area around a water connection and a sterilized area of all hospital wards was supervised by the Infection Control Team (ICT). The equipments which do not have the required facility criteria were improved by the construction. Moreover, the education about the clean maintenance was provided to the local by the ICT. The detectable amount of PA and MDRP of culture specimen as well as the number of patients were reported monthly before and after the hospital environment maintenance. Result: The monthly average of PA of culture specimen was reduced by half from 119.5 cases to 59.5 cases after the hospital environment maintenance, and the number of patients infected with PA was reduced to 10 patients or less three months later. The number of patients infected with MDRP was reduced from 9.3 to 1.8 after the hospital environmental maintenance, and there was no patients infected with MDRP 3 months later. Total cost for the maintenance was 28.000 dollars.