J. Graham Douglas

A FULLY AUTOMATED ALGORITHM FOR THE DETERMINATION OF RESPIRATORY RATE FROM THE PHOTOPLETHYSMOGRAM

Objective. To determine if an automatic algorithm using wavelet analysis techniques can be used to reliably determine respiratory rate from the photoplethysmogram (PPG). Methods. Photoplethysmograms were obtained from 12 spontaneously breathing healthy adult volunteers. Three related wavelet transforms were automatically polled to obtain a measure of respiratory rate. This was compared with a secondary timing signal obtained by asking the volunteers to actuate a small push button switch, held in their right hand, in synchronisation with their respiration. In addition, individual breaths were resolved using the wavelet-method to identify the source of any discrepancies. Results. Volunteer respiratory rates varied from 6.56 to 18.89 breaths per minute. Through training of the algorithm it was possible to determine a respiratory rate for all 12 traces acquired during the study. The maximum error between the PPG derived rates and the manually determined rate was found to be 7.9%. Conclusion. Our technique allows the accurate measurement of respiratory rate from the photoplethysmogram, and leads the way for developing a simple non-invasive combined respiration and saturation monitor.

Pharmacokinetic factors in the modern drug treatment of tuberculosis.

Tuberculosis is increasing in prevalence throughout the world, particularly in sub-Saharan Africa, Asia and Latin America. This resurgence can partly be attributed to increasing poverty, particularly in developing countries, and the human immunodeficiency virus (HIV) pandemic. However, there is also increasing concern at the development of multidrug-resistant tuberculosis caused by the misuse of the agents available.The modern treatment of patients with tuberculosis should start, in most cases, with 4 first-line agents in order to minimise the risk of drug resistance developing. A 6-month drug regimen is usually satisfactory for pulmonary and nonpulmonary tuberculosis, although not for patients with tuberculous meningitis, in whom a longer course of treatment is required. Coinfection with HIV may produce an atypical clinical and radiological presentation, but the treatment regimen is essentially similar to other situations. Several of the first-line agents, in particular rifampicin (rifampin) and isoniazid, are likely to cause clinically significant drug interactions and/or toxicity, particularly in patients with HIV infection.Consideration of the pharmacodynamic and pharmacokinetic interactions between the host, the mycobacterium and the drug may contribute to the development of pharmacokinetically optimised regimens that make best use of the existing range of antituberculosis drugs. However, such idealised regimens need to be tested in prospective clinical trials. The use of therapeutic drug monitoring in selected groups of patients may improve outcomes, avoid drug toxicity and reduce the development of multidrug-resistant tuberculosis.The management of multidrug-resistant tuberculosis requires a high level of clinical expertise and such patients should start on at least 5 drugs to which the organism is thought to be susceptible.Up to 50% of patients with tuberculosis may not adhere to their drug regimen, resulting in persisting infectiousness, relapse or the development of drug resistance. Directly observed treatment with antituberculosis drugs, combined with a serious commitment to tuberculosis control, is required if we are to combat this increasing epidemic.

ABC of chronic obstructive pulmonary disease: Non-pharmacological management

Chronic obstructive pulmonary disease (COPD) is a progressive and largely irreversible disorder. Unsurprisingly, drugs alone cannot ensure optimum short and long term outcomes. As a consequence, there is increasing interest in the role of non-drug strategies and multi-disciplinary team input in the overall management of COPD. Pulmonary rehabilitation should be offered to most patients with COPD A determined attempt should be made to break the vicious circle of worsening breathlessness, reduced physical activity, and deconditioning Depending on local availability, consider referring all COPD patients—irrespective of age, functional limitation, and smoking status—for pulmonary rehabilitation. This is “a multidisciplinary programme of care for patients with chronic respiratory impairment that is individually tailored and designed to optimise physical and social performance and autonomy.” A suitable programme is important in breaking the vicious cycle of worsening breathlessness, reduced physical activity, and deconditioning that many patients experience, and pulmonary rehabilitation plays a major role in restoring patients to an optimally functioning state. For example, early intervention after an acute exacerbation of COPD can produce clinically significant improvements in exercise capacity and health. The ideal programme should consist of several components, including exercise training, education, and nutritional support. View this table: Nutritional advice for COPD patients Exercise training— Outpatient pulmonary rehabilitation programmes typically run for two months, with two or three sessions of supervised exercise each week. Patients are encouraged to exercise at home and record their achievements, so that progress can be monitored. Studies have shown that physiological changes provided by endurance training take place at the level of skeletal muscle, even during sub-maximal exercise. Exercise training can improve exercise tolerance, symptoms, quality of life, peak oxygen uptake, endurance time during sub-maximal exercise, functional walking distance, and peripheral and respiratory muscle strength. Education— This generally comprises various forms of goal directed and systematically applied communication aimed at improving …

Duration of intravenous therapy and hospital stay according to choice of empirical antimicrobial treatment for community-acquired respiratory infection.

A review of patients admitted to medical wards with respiratory infection was undertaken to look for differences in duration of intravenous (IV) therapy and length of patient stay based on the class of IV antimicrobial used in treatment. Data was analysed from 231 patients with community-acquired respiratory infection who were treated empirically for at least 24 h with either an IV cephalosporin (146 patients) or an IV penicillin or macrolide (85 patients). The severity of illness and indication for IV treatment was similar in each group. Those treated with a cephalosporin received IV therapy for a significantly longer period (mean = 4.44 days, SD = 2.6) than those given a penicillin or macrolide (mean = 3.3 days, SD = 1.8): P < 0.001. Patient stay was significantly longer in the cephalosporin group (mean = 11.6 days, SD = 10.4) than the penicillin/macrolide group (mean = 9.4 days, SD = 6.3): P = 0.04. These differences are most readily accounted for by the absence from the hospital formulary of a third generation oral cephalosporin, a drug that might be regarded as an obvious form of follow-on therapy in patients treated empirically with an injectable cephalosporin.

Early supported discharge schemes in older patients with an exacerbation of chronic obstructive pulmonary disease: A real life experience

Chronic obstructive pulmonary disease (COPD) is the most common medical condition necessitating admission to hospital in the UK and has the highest prevalence in the elderly. With an increasingly aged population, the number of older patients e across Europe and in countries with high COPD prevalence e admitted to hospital with an exacerbation is likely to lead to potential financial and bed occupancy concerns. Early supported discharge schemes e whereby patients admitted to hospital with an exacerbation are allowed home sooner than would normally be anticipated e have been shown to be feasible in selected patients in randomised controlled trials. However, few data have evaluated whether they can be successfully used in older patients in a ‘‘real-life’’ setting. In Aberdeen Royal Infirmary, Scotland, UK, we run an early supported discharge service whereby agreeable patients (many of them elderly) admitted with an exacerbation of COPD are identified, treatment is optimised and discharge is arranged (usually within several days) with nurse led community follow-up (involving daily telephone calls or home visits) for up to 2 weeks. Patients with adverse clinical features (e.g. a respiratory acidosis, confusion, extreme breathlessness, undiagnosed chest pain and significant concomitant medical disorders) and undesirable social circumstances (e.g. no telephone, inability to self-care or unfavourable domestic arrangements) are usually considered unsuitable to be entered into the scheme. We performed a retrospective analysis of all patients who had been through our service aged 65 between 2002 and 2007. During this period, 528 different patients were identified and 925 early supported discharges took place. The mean age of patients, number of early supported discharge episodes and proportion of patients needing readmission for each year are shown in the table. All patients readmitted failed to adequately