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Biomedical subjects

A K Simonds

Publications and source records attributed to A K Simonds.

At least 37 records · Page 2Linked to original sources
PubMed2002

Noninvasive ventilation for chest wall and neuromuscular disorders.

Neuromuscular and chest wall disorders are individually uncommon but together form an important group of conditions that can lead to chronic ventilatory failure. This is best recognised in scoliosis, kyphosis, following a thoracoplasty, in muscular dystrophies, such as Duchenne muscular dystrophy (DMD), and myotonic dystrophy, after poliomyelitis and with motor neurone disease (amyotrophic lateral sclerosis). If bulbar function is impaired, tracheostomy ventilation may be required, but in other situations, noninvasive ventilation is preferable. Positive pressure techniques using nasal and face masks are usually the first choice, but negative pressure ventilation is an alternative. There are no randomised-controlled trials regarding the indications for initiating noninvasive ventilation, but this is usually provided if there are symptoms due to nocturnal hypoventilation or right heart failure in the presence of a raised carbon dioxide tension in arterial blood (Pa,CO2) either at night or, more usually, in the daytime as well. There is no evidence that "prophylactic" ventilatory support is of benefit if this is provided before ventilatory failure has appeared. Careful selection of patients is required, especially in the presence of progressive neuromuscular disorders such as DMD and motor neurone disease. There are no randomised-controlled trials concerning the outcome of noninvasive ventilation in these conditions, but studies have shown an improved quality of life, physical activity and haemodynamics, normalisation of blood gases and slight improvement in other physiological measures, such as the vital capacity and maximal mouth pressures. Survival in chest wall disorders is approximately 90% at 1 yr and 80% at 5 yrs, and similar figures have been obtained in nonprogressive neuromuscular conditions. If, however, the underlying disorder is deteriorating, particularly if it involves the bulbar muscles, it may limit survival despite the provision of adequate noninvasive ventilatory support.

Humans↗
PubMed2001

Lung volume reduction surgery in a ventilated patient with severe pulmonary emphysema.

There are a limited number of reports in the literature cocerning lung volume reduction surgery in patients receiving mechanical ventilation. We present a case in which a ventilator-dependent patient with apparent endstage pulmonary emphysema underwent lung volume reduction with a successful outcome. Although the role of this procedure for selected nonventilated patients has been widely discussed its use in ventilated patients is still not clearly defined. We show that lung volume reduction surgery may facilitate ventilatory weaning in such cases and improve functional status.

Female↗
PubMed2001

Impact of age on breathing and resistive pressure in people with and without sleep apnea.

We investigated the effect of age on breathing and total pulmonary resistance (RL) during sleep by studying elderly (>65 yr) and young (25-38 yr) people without sleep apnea (EN and YN, respectively) matched for body mass index (BMI). To determine the impact of sleep apnea on age-related changes in breathing, we studied elderly and young apneic patients (EA and YA, respectively) matched for apnea and BMI. In all groups (n = 11), breathing during periods of stable sleep was analyzed to evaluate the intrinsic variability of respiratory control mechanisms. In the absence of sleep apnea, the variability of the breathing was similar in the elderly and young [mean (+/- SD) coefficient of variation (CV) of tidal volume (VT); wake: EN 21.0 +/- 14.9%, YN 14.7 +/- 5.5%; sleep: EN 14.0 +/- 6.0%; YN 11.5 +/- 6.4%]. In patients with sleep apnea, breathing during stable sleep was more irregular, but there were no age-related differences (CV of VT; wake: EA 22.0 +/- 11.6%, YA 16.7 +/- 11.3%; sleep: EA 32.8 +/- 24.9%, YA 25.2 +/- 16.3%). In addition, EN tended to have a higher RL (n = 6, RL midinspiration, wake: EN 7.1 +/- 3.0; YN 9.1 +/- 6.4 cmH(2)O. l(-1). s, sleep: EN 17.5 +/- 11.7; YN 9.8 +/- 2.0 cmH(2)O. l(-1). s). We conclude that aging per se does not contribute to the intrinsic variability of respiratory control mechanisms, although there may be a lower probability of finding elderly people without respiratory instability.

Adult↗
PubMed2000

Outcome of paediatric domiciliary mask ventilation in neuromuscular and skeletal disease.

Noninvasive positive pressure ventilation delivered by nasal mask or facemask has been used widely in the last decade to manage chronic ventilatory failure in adults with neuromuscular and chest wall disease. However, it has been thought that paediatric patients would not be able to tolerate masks, and previous anecdotal reports on the paediatric application of mask ventilation have not assessed the effects on nocturnal and arterial blood gas control. Domiciliary mask ventilation has been used in 40 children with ventilatory insufficiency due to congenital neuromuscular and skeletal disease aged 9 months-16 yrs. Eighteen patients had symptomatic nocturnal hypoventilation, 17 had diurnal ventilatory failure, three were referred for weaning and two had frequent chest infections associated with sleep-disordered breathing. Thirty eight of the 40 patients tolerated mask ventilatory support long-term. Diurnal mean+/-SD oxygen tension in arterial blood (Pa,O2) increased from 8.5+/-1.8-10.9+/-1.7 kPa (p<0.001) and mean carbon dioxide tension in arterial blood (Pa,CO2) fell from 7.0+/-1.6-5.9+/-0.8 kPa (p=0.01) following initiation of ventilatory support. Mean and minimum nocturnal Pa,O2 and peak transcutaneous carbon dioxide tension (Ptc,CO2) (n=21) improved significantly. Mask ventilation can be used successfully in young children and reverses ventilatory insufficiency due to congenital neuromuscular and skeletal disease.

Adolescent↗
PubMed2000

Nasal ventilation in progressive neuromuscular disease: experience in adults and adolescents.

A nihilistic approach to ventilatory support in progressive neuromuscular disorders is no longer acceptable. Noninvasive ventilation may improve survival and quality of life in some patients. In other situations, worthwhile palliation of symptoms of nocturnal hypoventilation and dyspnoea may be achieved. Noninvasive ventilation combined with cough assistance may obviate the need for tracheostomy ventilation, or can be employed as part of a staged approach. Individual titration of ventilatory support to meet the needs of the individual and family is vital. The participation of the patient, family and carers in decision-making is crucial and advanced directives are likely to be used increasingly.

Adolescent↗
PubMed2000

Non invasive ventilation.

Non-invasive ventilation refers to the technique of providing ventilatory support to a patient without an endo/orotracheal airway. It is a promising and rapidly upcoming new technique and is being used as first line therapy in a wide variety of conditions causing respiratory failure. The major indications for its use include respiratory failure due to a variety of causes (chest wall abnormalities, neuromuscular disease, COPD), weaning and stabilization of cardio-respiratory status before and after surgery. Patients who are candidates for this modality usually have a hypercapnic respiratory failure but are able to protect the airway and cooperate with treatment. The biggest advantage of the technique is its simplicity and avoidance of complications of intubation like trauma, infection and delayed complications like tracheal stenosis. Patient comfort is significantly improved and important functions like speech, swallowing and cough are preserved. Several purpose built ventilators are available for use including pressure preset and volume present machines, each of which have their own advantages and disadvantages in clinical practice. A range of patient interfaces is available. The initiation of non-invasive ventilation is much easier as compared to invasive ventilation and can be done for most patients in an intermediary care unit thereby cutting down treatment costs and saving precious intensive care beds. Titration of ventilatory parameters can usually be done using simple tests like oxymetry and blood gases. Several technique related problems like skin pressure sores, nasal symptoms and abdominal distension can be managed with simple measures. Non invasive ventilation has got a special and evolving role in management of COPD, both in acute exacerbations and chronic respiratory failure. In short, the advantages of this form of ventilation are numerous and physicians must familiarize themselves with this new technique, facilities for which should be available in all hospitals admitting patients with respiratory failure.

Humans↗
PubMed1999

Magnetic resonance navigator echo diaphragm monitoring in patients with suspected diaphragm paralysis.

Real-time magnetic resonance (MR) navigator echo (NE) monitoring of the diaphragm is now possible. Using this technique, temporal changes in diaphragm position can be analyzed in a non-invasive fashion, without x-ray exposure. In this preliminary study, we have optimized three NE parameters (the NE column area, the NE repeat time, and the location of the NE on the diaphragm surface), and demonstrated the clinical application of MR NE diaphragm monitoring in patients with suspected diaphragm paralysis. The NE parameters were defined in 10 healthy volunteers, and diaphragm traces were scored for variance in NE diaphragm position registration. Using the optimal NE column parameters, we investigated four patients with diaphragm paralysis, one of whom required positive pressure ventilation while in the MR scanner, to show the utility of this technique. The NE diaphragm position registration was significantly affected by the area of the NE column, with poor position registration for the smallest column area (2.25 cm2 vs. 4 cm2 vs. 6.25 cm2, variance 6.3 vs. 0.6 vs. 0.3, P = 0.006). Diaphragm position registration was also significantly affected by the NE repeat time, with misregistration for the shortest repeat time (250 msec vs. 500 msec vs. 1000 msec, variance 11.9 vs. 0.6 vs. 1.0, P = 0.02), and data clipping, with loss of end-expiratory and end-inspiratory position registration, for the longest repeat time. Finally, if the NE was positioned too anteriorly, the diaphragm traces were of poor quality (anterior vs. dome vs. posterior, variance 11.8vs. 0.6vs. 3.2, P < 0.001). Application of the technique confirmed diaphragm paralysis in all four patients. The technique can be applied during positive pressure ventilation if necessary. The optimal NE parameters for diaphragm monitoring at 0.5 T were: column area, 400 mm2; NE repeat time; 500 msec; NE column positioned on the diaphragm dome. MR NE diaphragm monitoring provides a safe, non-invasive method of assessing diaphragm motion in patients with suspected diaphragm paralysis and may prove useful for long-term follow-up and monitoring of therapeutic interventions in these subjects.

Adult↗
PubMed1999

A three-centre prospective pilot study to elucidate the effect of uvulopalatopharyngoplasty on patients with mild obstructive sleep apnoea due to velopharyngeal obstruction.

In this paper we describe the outcome of a prospective study designed to investigate the role of uvulopalatopharyngoplasty in the management of mild obstructive sleep apnoea. A group of 21 patients fulfilling strict inclusion and exclusion criteria underwent uvulopalatopharyngoplasty performed by a single surgeon using a modified technique. Specifically designed daily pain questionnaires were completed by the patients for 2 weeks after surgery and the morbidity associated with the procedure was assessed at 2, 6 and 12 weeks after operation. Thirteen of the 21 patients underwent a postoperative sleep study at 3 months after operation. The outcome measures used were the apnoea/hypopnoea index, the minimum O2 saturation, the sleep arousal index, the sleep architecture the Epworth Sleepiness Scale score, the subjective improvement in both the patient's and their partner's sleep and the morbidity associated with uvulopalatopharyngoplasty. We conclude that the patients with mild obstructive sleep apnoea most likely to obtain significant benefit from uvulopalatopharyngoplasty are those with a body mass index of between 27 and 30 with no cephalometric disproportion, those with frequent arousals not associated with periodic limb movements, those whose sleep related breathing disorder is not positional and most importantly those with symptomatic day time sleepiness.

Adult↗
PubMed1998

Nasal ventilation.

Nasal intermittent positive pressure ventilation is likely to have an increasing role in the management of acute ventilatory failure, weaning, and chronic ventilatory problems. Further improvements in ventilator and mask design will be seen. Appropriate application is likely to reduce both mortality and admissions to intensive care, while domiciliary use can improve life expectancy and/or quality of life in chronic ventilatory disorders. As with any new technique, enthusiasm should not outweigh clear outcome information, and possible new indications should always be subject to careful assessment.

Acute Disease↗
PubMed1998

Impact of nasal ventilation on survival in hypercapnic Duchenne muscular dystrophy.

BACKGROUND: Respiratory failure is the commonest cause of death in patients with Duchenne muscular dystrophy (DMD). Life expectancy is less than one year once diurnal hypercapnia develops. This study examines the effects of nasal intermittent positive pressure ventilation (NIPPV) on survival in symptomatic Duchenne patients with established ventilatory failure. METHODS: Nocturnal NIPPV was applied in 23 consecutive patients with DMD of mean (SD) age 20.3 (3.4) years who presented with diurnal and nocturnal hypercapnia. RESULTS: One year and five year survival rates were 85% (95% CI 69 to 100) and 73% (95% CI 53 to 94), respectively. Early changes in arterial blood gas tensions following NIPPV occurred with mean (SD) PO2 increasing from 7.6 (2.1) kPa to 10.8 (1.3) kPa and mean (SD) PCO2 falling from 10.3 (4.5) kPa to 6.1 (1.0) kPa. Improvements in arterial blood gas tensions were maintained over five years. Health perception and social aspects of SF-36 health related quality of life index were reported as equivalent to other groups with nonprogressive disorders using NIPPV. CONCLUSIONS: Nasal ventilation is likely to increase survival in hypercapnic patients with Duchenne muscular dystrophy and should be considered as a treatment option when ventilatory failure develops.

Adolescent↗
PubMed1998

Weaning difficulties.

All units providing ventilatory support will experience patients with weaning difficulties. The factors which contribute to weaning problems include the pathophysiology of the illness, the extent of underlying chronic disease, and equipment, physician-related and organisational issues. In this article ways to resolve these problems are outlined.

Female↗