Shoulder pain is very common, affecting 14-21 % of the population at some time during their lifetime. The aims of this thesis were to improve the understanding of various aspects concerning the pathogenesis and treatment of subacromial pain and rotator cuff tears. Patients and healthy individuals were examined and compared in five studies: Study I) Seventy patients were retrospectively examined, clinically and with ultrasound, 15 years after arthroscopic subacromial decompression. All patients had an intact rotator cuff at surgery. Ultrasound showed significantly fewer rotator cuff tears compared to the prevalence of asymptomatic tears reported in the literature for the same age group. This indicates that arthroscopic subacromial decompression might protect the rotator cuff. Study II) Forty-two patients were retrospectively examined, clinically and with ultrasound, 39 months (mean) after an acute rotator cuff repair. All patients had pseudoparalysis after trauma, a full thickness tear and no previous history of shoulder symptoms. A delay in surgical treatment of three months and the number of tendons injured did not affect the outcome. Age affected outcome negatively. Study III) Plasma samples from 17 patients with cuff tears and 16 plasma samples from healthy age- and gender-matched controls were collected and analysed regarding the levels of matrix metalloproteinases and their inhibitors, TIMP1-4. Elevated levels of TIMP-1 were found in the patients with cuff tears compared to controls. Higher levels of TIMP-1, TIMP-3 and MMP-9 were found in patients with full-thickness tears compared to patients with partial-thickness tears. Study IV) Ninety-seven patients with longstanding subacromial pain, on the waiting-list for arthroscopic subacromial decompression, were prospectively randomised to specific shoulder exercises or control exercises for three months. Thereafter they were clinically examined and asked if they still wanted surgery. The specific shoulder exercises focusing on eccentric exercise for the rotator cuff and scapula stabilisers were found to be effective in reducing subacromial pain and improving shoulder function, thereby reducing the need for surgery. Study V) All patients including those operated, in Study IV were re-examined after one year using clinical assessment scores. The option of surgery was continuously available up to the one-year follow-up. Ultrasound and radiological examinations performed at inclusion were analysed in relation to the choice of surgery. The positive effects of the specific exercise programme were maintained after one year and significantly fewer patients in this group chose surgery. Surgery was significantly more often chosen by patients who had a low baseline shoulder score, and/or a full thickness rotator cuff tear.  All patients showed significant improvement in the clinical scores one year after inclusion or one year after surgery. These results support the concept that subacromial pain has a multifactorial aetiology and that the first line of treatment should be specific shoulder exercises. When conservative treatment fails, an acceptable result can be achieved with arthroscopic subacromial decompression. The rotator cuff status is important to consider when treating and studying these patients.

Pulmonary aspiration in mechanical ventilation occurs despite appropriate inflation of the tracheal tube cuff. After anaesthesiath is can causep ostoperative and, in critically ill patients, ventilator-associated pneumonia. Cuff over-inflation exerts excessive pressure on the tracheal mucosa causing injury. High volume low pressure (HVLP) cuffs permit wall pressure control as the intracuff pressure (CP) is the tracheal wall pressure (TWP). Unfortunately, at the cuff wall, folds and channels and, therefore, fluid leakage occur. Low volume high pressure (LVHP) cuffs develop neither folds nor associated leakage, but TWP is not easily inferred from CP and excessive pressures can result in tracheal injury. This thesis examines the problem of aspiration in a model, in anaesthetised patients and in the critically ill. In the model, protection against leakage resulted from positive end-expiratory pressure and cuff lubrication. Two tracheal cuff prototypes are introduced. Firstly, the compliant HVLP cuff is one with a tapered shape made of highly compliant material. Within the model this produced a circumferential band at the cuff wall without folds thus effectively eliminating channels and leakage. Secondly, the prototype pressure limited cuff (PLC) is a latex LVHP cuff with inflation characteristics such that TWP can be inferred from CP and maintained at an acceptable level. Within the model the PLC prevented leakage at acceptable TWPs. For clinical use a constant pressure inflation device is required to provide uninterrupted protection, although notably HVLP cuffs allow leakage despite this. The PLC prevented dye aspiration in 100% of tracheally intubated critically ill patients compared with 13% of the control HVLP group (p<0.01). A silicone cuff with similar inflation characteristics, yet improved biocompatability and shelf life, prevented dye aspiration in 100% of patients with tracheostomies compared to 0% of the HVLP control group (p=0.001). HVLP cuff lubrication delayed dye aspiration for 1 to 5 days (p<0.05).

The oscillometric method for blood pressure measurement has been known for over a century. It was overshadowed by the classic stethoscope and cuff method until more recently when its ease of automation became useful. It is now found in the automated blood pressure cuffs used in hospitals, doctor's offices, pharmacies, and devices sold for home use. It still challenges accurate blood pressure measurement, however, due to its difficulty in compensating for pregnancy, age, hypo-, and hypertension. Global sensitivity analysis methods were used to develop a model that focuses on the most important system parameters. The most influential biological and design parameters were identified allowing the removal or fixing of less influential parameters, and the replacement of subsystems with linear models, with minimal effect on the overall system accuracy. The developed model allows for the investigation and development of new methods for extracting parameter information from the oscillometric signals. This is illustrated by the development of a method to extract the artery's cross-sectional area from standard oscillometric output. The system design requirements for accurate measurement of blood pressure are examined and discussed with recommendations for system parameter adjustment. The model's performance and usefulness is highlighted with modelled case studies of potential real-world applications for subjects with parameters or inputs for which the oscillometric method would find it difficult to compensate. Through the use of the developed model to compensate for the system errors, the measurement error can be reduced by half. Highlighting the important system parameters allows the engineer to focus on choosing the design parameters over which she or he has control. The system model provides the ability to experiment with the cuff design choices and provides information regarding system performance under conditions that are historically difficult to measure accurately. The developed model's usefulness is illustrated by applying it to parameter extraction, and to the compensation of oscillometric blood pressure readings.

Vagus nerve stimulation (VNS) is an approved therapy for patients suffering from refractory epilepsy. While VNS is currently an open loop system, making the system closed loop can improve the therapeutic efficacy. Electrical recording of peripheral nerve activity using a nerve cuff electrode is a potential long-term solution for implementing a closed-loop controlled VNS system. However, the clinical utility of this approach is significantly limited by various factors, such as poor signal-to-noise ratio (SNR) of the recorded electroneurogram (ENG). In this study, we investigated the effects of (1) modifying the electrode contact dimensions, (2) implementing an external shielding layer on the nerve cuff electrode and (3) exploring shielded bipolar nerve cuff designs on the recorded ENG. Findings from both computer simulations and animal experiments suggest that significant improvements in peripheral nerve recordings can be achieved.

Vagus nerve stimulation (VNS) is an approved therapy for patients suffering from refractory epilepsy. While VNS is currently an open loop system, making the system closed loop can improve the therapeutic efficacy. Electrical recording of peripheral nerve activity using a nerve cuff electrode is a potential long-term solution for implementing a closed-loop controlled VNS system. However, the clinical utility of this approach is significantly limited by various factors, such as poor signal-to-noise ratio (SNR) of the recorded electroneurogram (ENG). In this study, we investigated the effects of (1) modifying the electrode contact dimensions, (2) implementing an external shielding layer on the nerve cuff electrode and (3) exploring shielded bipolar nerve cuff designs on the recorded ENG. Findings from both computer simulations and animal experiments suggest that significant improvements in peripheral nerve recordings can be achieved.

Rotator cuff disorders encompass a range of impairments from tendinopathy to partialor full-thickness rotator cuff tears, and represent the largest subgroup of shoulder pain. Rotator cuff tears, most of which are atraumatic, are common in adults with shoulder pain and are strongly associated with increasing age. Conservative treatment including physiotherapy is the first-line treatment, but some patients do not respond, and ultimately require surgery. Early predictions of response could allow individuals’ care pathways to be optimised, preventing unnecessary delays and suffering and benefiting patients and healthcare providers alike. My primary aim was to develop a prognostic model for the outcome of physiotherapy in adults with painful atraumatic partial-thickness tears (PTTs) of the rotator cuff. This was addressed by a prospective prognostic model study. The study was underpinned by a systematic review of prognostic models in adults undergoing physiotherapy for painful rotator cuff disorders and was further informed and complemented by the following work: the development and validation of the physiotherapy protocol for the prognostic study; the identification, selection and definition of the candidate prognostic factors for the prognostic study; the estimation of the Minimal Important Difference (MID) of the study’s primary outcome measure (the Western Ontario Rotator Cuff Index, WORC); and an exploratory responder analysis of the WORC outcome scores. The prognostic systematic review, prognostic study, MID analysis and responder analysis are original contributions to knowledge. The prognostic systematic review revealed important methodological deficiencies in the five included studies, and no clinically usable model. No study addressed a distinct PTT population. The process of identifying factors for my own prognostic model study revealed a lack of knowledge about the prognostic relevance of factors. All of the candidate models I explored in my prognostic study (n sample = 65, n analysed = 61) had low performance and precision. The estimated MID of the WORC was -300. The responder analysis resulted in different proportions of responders to treatment depending on the responder definition. My results highlight the difficulties involved in predicting outcomes in the field of shoulder pain and rotator cuff disorders, and the need for methodologically sound prognosis research.

Currently, rotator cuff injuries are the most common problem for the shoulder and accounted for 4.1 million physicians visits. Partial and full thickness tears are more common in people over the age of 50. The increased prevalence of rotator cuff injuries in the United States population certainly affects the working population and often represents a significant economic burden for employers. Few studies have examined outcomes in worker compensation patients or considered biopsychosocial predictive variables for rotator cuff repairs. The current study aimed to characterize injured workers who have undergone rotator cuff repairs across a number of pre- and postprocedural variables, evaluate multidimensional functional and quality of life outcomes, and examine biopsychosocial variables predictive of success and failure in this sample. The current study examined 93 injured workers who had undergone at least one rotator cuff repair within the past five years. Participants were solicited through the Worker’s Compensation Fund of Utah (WCF) computerized database. The current study used a retrospective cohort design, patients’ medical charts were reviewed, and various preprocedural variables were coded for analysis including age at the time of the rotator cuff repair, lawyer involvement in the claim, prior shoulder surgery history, and quantity of other compensation claims. Of the total sample, 47 patients (50.5%) were contacted and completed outcome surveys that assessed patient satisfaction, shoulder functional impairment, disability status, and general physical and mental health functioning. Findings revealed that approximately one third of the patients were totally disabled (29.8%), had poor shoulder specific functioning (36.2%), and were dissatisfied with their current shoulder condition (31.7%). A multivariate regression model was utilized in predicting patient outcomes. Specifically, the number of WCF claims of the patient was a robust predictor of multidimensional outcomes, while age and gender were less predictive of outcomes, and the presence of a prior shoulder surgery reflected no predictive power. Results of descriptive, correlational, and regression analyses are compared to existing data for rotator cuff repair patients when available or to other surgical procedures with similar populations. The study limitations are discussed, such as small sample size, the retrospective design, and lack of matched controls.

No description available.

No description available.

<p>Over-inflation of an endotracheal tube (ETT) cuff may lead to tracheal necrosis, whereas under- inflation increases the risk of pulmonary aspiration. The objectives of this 2-phase study were to 1) identify the frequency of abnormal ETT cuff inflation in anesthetized dogs, 2) evaluate ETT cuff inflation with 3 devices (regular syringe, Tru-CuffTM syringe, AG Cuffill syringe) in achieving proper cuff pressure (20-30 cmH2O). Dogs undergoing general anesthesia at Purdue Veterinary Medicine Teaching Hospital (PVMTH) were included. The standard operating procedure (SOP) of PVMTH was used for ETT size selection and cuff inflation. The results of objective 1 showed that 50 of the 80 dogs required ETT cuff inflation. Among these 50 dogs, only 14% had proper cuff inflation; 76% of the cuffs were over-inflated and 10% were under-inflated. For objective 2, 90 dogs were equally assigned to the 3 devices for ETT cuff inflation and cuff pressure was assessed with an aneroid manometer. The results showed that 80% of the ETT cuffs were over-inflated with the regular syringe, whereas only 6.7% and 3.3% ETT cuffs were over-inflated with the Tru-CuffTM and AG Cuffill syringes, respectively. The AG Cuffill syringe treatment group had a significantly higher percentage of proper inflated ETT cuffs (86.7%; both p < 0.05) compared to the other two groups (regular [3.3%]; Tru-CuffTM [50%]). We concluded that there was a high frequency of improper ETT cuff inflation when using SOP coupled with a regular syringe. The use of an AG Cuffill syringe significantly reduced improper ETT cuff inflation.</p>