Development of patient-specific computer simulation tools for endoscopic scoliosis surgery

Endoscopic approaches for anterior correction of idiopathic scoliosis are a relatively new surgical technique. This paper describes the development of patient-specific finite element modelling techniques to investigate the biomechanics of single rod anterior scoliosis correction. Spinal geometry is obtained from pre-operative CT scans and material properties for osteo-ligamentous spinal tissues are based on existing literature. The techniques being developed will allow pre-surgical prediction of stresses, forces and deformations in spinal tissues, rods and screws under post-operative physiological loads.

Good nutrition for good surgery: clinical and quality of life outcomes

Undernutrition is common in patients admitted for surgery and is often unrecognised, untreated and worsens in hospital. The complex synergistic relationship between nutritional status and the physiological responses to surgery puts patients at high nutritional risk. There are clear prospective associations between inadequate nutritional status and the risk of poorer outcomes for surgical patients, including infection, complications and length of stay. However, practically and ethically evidence that nutritional interventions can significantly reduce these poor outcomes is difficult to obtain. Nevertheless health professionals have a duty of care to ensure our patients are properly fed, by whatever means, to meet their physiological requirements.

An epidemiological study of the relationship between time to surgery and health status for elderly patients with a hip fracture

A hip fracture causes permanent changes to life style for older people. Further, two important mortality indicators found post operatively for this group include, the time until surgery after fracture, and pre-operative health status prior to surgery, yet no research is available investigating relationships between time to surgery and health status. The researchers aimed to establish the health status risks for patients aged over 65 years with a non-pathological hip fracture to guide nursing care interventions. A prospective cohort design was used to investigate relationships between time to surgery and measures on pre-operative health status indicators including, skin integrity risk, vigor, mental state, bowel function and continence. Twenty-nine patients with a mean age in years of 81.93 (SD,9.49), were recruited. The mean number of hours from time 1 assessment to surgery was 52.72 (SD,58.35) and the range was 1 hour to 219 hours. At Time 2, the mean scores of vigor and skin integrity risk were significantly higher, indicating poorer health status. A change in health status occurred but possibly due to the small sample size it was difficult to relate this result to time. However the results informed preoperative care prior to surgery, for this group.

The relationship between deformity correction and clinical outcomes after thoracoscopic scoliosis surgery : a prospective series of one hundred patients

Prospective clinical case series of 100 patients receiving thoracoscopic anterior scoliosis correction surgery. The objective was to evaluate the relationship between clinical outcomes of thoracoscopic anterior scoliosis surgery and deformity correction using the Scoliosis Research Society (SRS) outcomes instrument questionnaire. The surgical treatment of scoliosis is quantitatively assessed in the clinic using radiographic measures of deformity correction, as well as the rib hump, but it is important to understand the extent to which these quantitative measures correlate with self-reported improvements in patients’ quality of life following surgery. A series of 100 consecutive adolescent idiopathic scoliosis patients received a single anterior rod via a thoracoscopic approach at the Mater Children’s Hospital, Brisbane, Australia. Patients completed SRS outcomes questionnaires pre-operatively and at 24 months post-operatively. There were 94 females and 6 males with a mean age of 16.1 years. The mean Cobb angle improved from 52º pre-operatively to 25º post-operatively (52%) and the mean rib hump improved from 16º to 8º (51%). The mean total SRS score for the cohort was 99.4/120. None of the deformity related parameters in the multiple regression were significant. However, patients with the lowest post-operative major Cobb angles reported significantly higher SRS scores than those with the highest post-operative Cobb angles, but there was no difference on the basis of rib hump correction. There were no significant differences between patients with either rod fractures or screw-related complications compared to those without complications.

A prospective pilot study evaluating the ‘cardiac decompensation score’ in the setting of intraaortic balloon counterpulsation

The study objective was to determine whether the ‘cardiac decompensation score’ could identify cardiac decompensation in a patient with existing cardiac compromise managed with intraaortic balloon counterpulsation (IABP). A one-group, posttest-only design was utilised to collect observations in 2003 from IABP recipients treated in the intensive care unit of a 450 bed Australian, government funded, public, cardiothoracic, tertiary referral hospital. Twenty-three consecutive IABP recipients were enrolled, four of whom died in ICU (17.4%). All non-survivors exhibited primarily rising scores over the observation period (p < 0.001) and had final scores of 25 or higher. In contrast, the maximum score obtained by a survivor at any time was 15. Regardless of survival, scores for the 23 participants were generally decreasing immediately following therapy escalation (p = 0.016). Further reflecting these changes in patient support, there was also a trend for scores to move from rising to falling at such treatment escalations (p = 0.024). This pilot study indicates the ‘cardiac decompensation score’ to accurately represent changes in heart function specific to an individual patient. Use of the score in conjunction with IABP may lead to earlier identification of changes occurring in a patient's cardiac function and thus facilitate improved IABP outcomes.

Analysis of cardiac and epileptic signals using higher order spectra

The theory of nonlinear dyamic systems provides some new methods to handle complex systems. Chaos theory offers new concepts, algorithms and methods for processing, enhancing and analyzing the measured signals. In recent years, researchers are applying the concepts from this theory to bio-signal analysis. In this work, the complex dynamics of the bio-signals such as electrocardiogram (ECG) and electroencephalogram (EEG) are analyzed using the tools of nonlinear systems theory. In the modern industrialized countries every year several hundred thousands of people die due to sudden cardiac death. The Electrocardiogram (ECG) is an important biosignal representing the sum total of millions of cardiac cell depolarization potentials. It contains important insight into the state of health and nature of the disease afflicting the heart. Heart rate variability (HRV) refers to the regulation of the sinoatrial node, the natural pacemaker of the heart by the sympathetic and parasympathetic branches of the autonomic nervous system. Heart rate variability analysis is an important tool to observe the heart's ability to respond to normal regulatory impulses that affect its rhythm. A computerbased intelligent system for analysis of cardiac states is very useful in diagnostics and disease management. Like many bio-signals, HRV signals are non-linear in nature. Higher order spectral analysis (HOS) is known to be a good tool for the analysis of non-linear systems and provides good noise immunity. In this work, we studied the HOS of the HRV signals of normal heartbeat and four classes of arrhythmia. This thesis presents some general characteristics for each of these classes of HRV signals in the bispectrum and bicoherence plots. Several features were extracted from the HOS and subjected an Analysis of Variance (ANOVA) test. The results are very promising for cardiac arrhythmia classification with a number of features yielding a p-value < 0.02 in the ANOVA test. An automated intelligent system for the identification of cardiac health is very useful in healthcare technology. In this work, seven features were extracted from the heart rate signals using HOS and fed to a support vector machine (SVM) for classification. The performance evaluation protocol in this thesis uses 330 subjects consisting of five different kinds of cardiac disease conditions. The classifier achieved a sensitivity of 90% and a specificity of 89%. This system is ready to run on larger data sets. In EEG analysis, the search for hidden information for identification of seizures has a long history. Epilepsy is a pathological condition characterized by spontaneous and unforeseeable occurrence of seizures, during which the perception or behavior of patients is disturbed. An automatic early detection of the seizure onsets would help the patients and observers to take appropriate precautions. Various methods have been proposed to predict the onset of seizures based on EEG recordings. The use of nonlinear features motivated by the higher order spectra (HOS) has been reported to be a promising approach to differentiate between normal, background (pre-ictal) and epileptic EEG signals. In this work, these features are used to train both a Gaussian mixture model (GMM) classifier and a Support Vector Machine (SVM) classifier. Results show that the classifiers were able to achieve 93.11% and 92.67% classification accuracy, respectively, with selected HOS based features. About 2 hours of EEG recordings from 10 patients were used in this study. This thesis introduces unique bispectrum and bicoherence plots for various cardiac conditions and for normal, background and epileptic EEG signals. These plots reveal distinct patterns. The patterns are useful for visual interpretation by those without a deep understanding of spectral analysis such as medical practitioners. It includes original contributions in extracting features from HRV and EEG signals using HOS and entropy, in analyzing the statistical properties of such features on real data and in automated classification using these features with GMM and SVM classifiers.

Effectiveness of nurse-led preoperative assessment services for elective surgery : a systematic review

Background--The admission and assessment of patients for elective procedures is a task faced by all healthcare organisations that provide elective surgical services. Several different strategies have been used to facilitate the management of these tasks. Nurse-led preadmission clinics or services have been implemented in many health services as one of these management strategies; however their effectiveness has not been established. Objectives--The objective of this review was to examine the available research on the effectiveness of nurse-led elective surgery preoperative assessment clinics or services on patient outcomes.--Results--Of the 19 included articles, there were 10 audits of patient and hospital data, 3 surveys or questionnaires, 3 descriptive studies, 1 action research design, 1 prospective observational study and 1 RCT. Five of ten studies reporting data on cancellations rates found that nurse-led preadmission services reduced the number of day-of-surgery cancellations. Non-attendance for surgery was also reduced, with nine studies reporting decreases in the number of patients failing to attend. Eight studies reporting data on patient or parent satisfaction found high levels of satisfaction with nurse-led preadmission services. Three of four studies investigating the effect of the nurse-led preadmission service on patient anxiety found a reduction in reported anxiety levels. Three studies found that preoperative preparation was enhanced by the use of a nurse-led preadmission service.--Conclusions--While all included studies reported evidence of effectiveness for nurse-led preadmission services on a wide range of outcomes for elective surgery patients, the lack of experimental trials means that the level of evidence is low, and further research is needed.--Implications for practice--Nurse-led preadmission services may be an effective strategy for reducing procedural cancellations, failure to attend for procedures, and patient anxiety, however currently the evidence level is low.