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Biomedical subjects

A K Simonds

Publications and source records attributed to A K Simonds.

At least 55 records · Page 3Linked to original sources
PubMed1995

Outcome of domiciliary nasal intermittent positive pressure ventilation in restrictive and obstructive disorders.

BACKGROUND: Nasal intermittent positive pressure ventilation (NIPPV) is a new technique which has rapidly supplanted other non-invasive methods of ventilation over the last 5-10 years. Data on its effectiveness are limited. METHODS: The outcome of long term domiciliary NIPPV has been analysed in 180 patients with hypercapnic respiratory failure predominantly due to chest wall restriction, neuromuscular disorders, or chronic obstructive lung disease. One hundred and thirty eight patients were started on NIPPV electively, and 42 following an acute hypercapnic exacerbation. Outcome measures were survival (five year probability of continuing NIPPV), pulmonary function, and health status. A crossover study from negative pressure ventilation to NIPPV was carried out in a subgroup of patients. RESULTS: Five year acturial probability of continuing NIPPV for individuals with early onset scoliosis (n = 47), previous poliomyelitis (n = 30), following tuberculous lung disease (n = 20), general neuromuscular disorders (n = 29), and chronic obstructive pulmonary disease (n = 33) was 79% (95% CI 66 to 92), 100%, 94% (95% CI 83 to 100), 81% (95% CI 61 to 100), 43% (95% CI 6 to 80), respectively. Most of the patients with bronchiectasis died within two years. One year after starting NIPPV electively the mean (SD) PaO2 compared with the pretreatment value was +1.8 (1.9) kPa, mean PaCO2 -1.4 (1.3) kPa in patients with extrapulmonary restrictive disorders, and PaO2 +0.8 (1.0) kPa, PaCO2 -0.9 (0.8) kPa in patients with obstructive lung disease. Arterial blood gas tensions improved in patients transferred from negative pressure ventilation to NIPPV. Health status was ranked highest in patients with early onset scoliosis, previous poliomyelitis, and following tuberculous lung disease. In the group as a whole health perception was comparable to outpatients with other chronic disorders. CONCLUSIONS: The long term outcome of domiciliary NIPPV in patients with chronic respiratory failure due to scoliosis, previous poliomyelitis, and chest wall and pulmonary disease secondary to tuberculosis is encouraging. The results of NIPPV in patients with COPD and progressive neuromuscular disorders show benefit in some subgroups. The outcome in end stage bronchiectasis is poor.

Administration, Intranasal↗
PubMed1995

Nocturnal assisted ventilation using bilevel positive airway pressure: the effect of expiratory positive airway pressure.

Increasing expiratory positive airway pressure (EPAP) has theoretical advantages during overnight nasal ventilation. We wanted to evaluate the effect of the addition of EPAP upon the control of nocturnal hypoventilation. Seven patients with neuromuscular/skeletal (NMS) disorder (mean +/- SD forced vital capacity (FVC) 1.06 +/- 0.28 l, arterial oxygen tension (PaO2) 9.1 +/- 0.6 kPa, and arterial carbon dioxide tension (PaCO2) 6.9 +/- 0.9 kPa), and seven patients with chronic obstructive pulmonary disease (COPD) (FEV1 0.46 +/- 0.14 l, PaO2 6.2 +/- 0.6 kPa, and PaCO2 8.4 +/- 1.1 kPa) all underwent full polysomnography on two nights during bilevel positive airway pressure (BiPAP) ventilation, with and without the addition of expiratory positive airway pressure, which was matched to the level of dynamic positive end-expiratory pressure (PEEP) or set at a minimum value of 5 cmH2O. In the group with neuromuscular/skeletal disorders the maximum transcutaneous carbon dioxide tension (PtcCO2) overnight was lower (inspiratory positive airway pressure (IPAP) 8.1 +/- 1.4 kPa, IPAP/EPAP 7.3 +/- 0.9 kPa) and the minimum level of arterial oxygen saturation (SaO2 min) increased (IPAP 77.1 +/- 6.7%, IPAP/EPAP 83.6 +/- 4.2%) when expiratory positive airway pressure was added. There were no differences in mean PtcCO2 or mean oxygen saturation, but sleep quality was worse (non-rapid eye movement (non-REM) sleep IPAP 266 +/- 44 min, IPAP/EPAP 226 +/- 32 min). In the patients with COPD, expiratory positive airway pressure conferred no advantage.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1994

A comparison of different modes of noninvasive ventilatory support: effects on ventilation and inspiratory muscle effort.

The aims of noninvasive ventilation include the correction of hypoventilation and unloading of inspiratory muscles. Volume cycled flow generators, bi-level positive airway pressure and continuous positive airway pressure techniques have all been used with face and nasal masks. We have compared these modes of ventilatory support, administered by a nasal mask in stable, awake outpatients with chronic obstructive pulmonary disease or neuromusculo-skeletal disease in respect of their effects on ventilation, inspiratory muscle effort and oxygen saturation. There were no clinically significant differences between the volume cycled flow generator and bi-level positive airway pressure methods; compared to spontaneous ventilation, oxygen saturation increased and inspiratory muscle effort decreased. Tidal volume increased and respiratory rate reduced, the largest changes occurring with bi-level positive airway pressure. Only the volume cycled flow generator increased minute ventilation significantly. Ventilation and inspiratory muscle effort were unaffected by continuous positive airway pressure but oxygen saturation was lower than during spontaneous ventilation. In awake, stable outpatients acclimatised to nasal ventilation there were no clinically significant differences between volume cycled flow generator and bi-level positive airway pressure techniques, but continuous positive airway pressure was less effective.

Aged↗
PubMed1993

Nasal intermittent positive pressure ventilation in neuromuscular and chest wall disease.

The short- and long-term physiological, functional and economic benefits of NIPPV in patients with chronic chest wall and stable neuromuscular disease have been confirmed and its advantages over non-invasive negative pressure ventilation outlined. Current research should help provide guidelines for patient selection and the most appropriate use of NIPPV in progressive neuromuscular disorders.

Home Care Services↗
PubMed1992

Domiciliary nocturnal nasal intermittent positive pressure ventilation in hypercapnic respiratory failure due to chronic obstructive lung disease: effects on sleep and quality of life.

BACKGROUND: Domiciliary assisted ventilation, using negative or positive pressure devices, is an effective treatment for respiratory failure due to chest wall deformity and neuromuscular disease. Negative pressure ventilators have been used with some success in patients with chronic obstructive lung disease in hospital, but attempts to continue treatment at home have been disappointing. This study evaluates the practicalities of nasal intermittent positive pressure ventilation at home in patients with chronic obstructive lung disease and the effect on sleep and quality of life. METHODS AND RESULTS: Twelve patients with chronic obstructive lung disease and hypercapnic respiratory failure received nasal intermittent positive pressure ventilation at home during sleep. At six months eight were continuing with the ventilation. One patient had died and three had withdrawn because they were unable to sleep with the equipment. Full polysomnography performed during ventilation in patients continuing treatment at six months showed an increase in mean PaO2 of 11% (+2% to +23%) and lower mean transcutaneous carbon dioxide tensions (by -2.7 (-1.3 to -5.1) kPa) overnight compared with spontaneous breathing before the start of nasal intermittent positive pressure ventilation. Total sleep time and sleep efficiency changed during ventilation by +72.5 (+21 to +204) minutes and +5% (-3% to +30%) respectively; sleep architecture and the number of arousals were unchanged. Quality of life did not change but was no worse during ventilation. At one year seven patients were still using the ventilator and PaCO2 and bicarbonate ion concentration during the day had improved further by comparison with the values at six months (change from baseline -1.7 (-2.1 to -0.6) kPa, p less than 0.05, and -6.3 (-11.9 to -4) mmol/l, p less than 0.05). CONCLUSIONS: Nasal intermittent positive pressure ventilation can be used effectively at home during sleep in selected patients with chronic obstructive lung disease. Its future place in management can be established only by formal comparison with long term oxygen therapy.

Female↗
PubMed1992

Nasal ventilation to facilitate weaning in patients with chronic respiratory insufficiency.

BACKGROUND: The non-invasive technique of nasal intermittent positive pressure ventilation (NIPPV) has an established role in providing domiciliary nocturnal ventilatory support in patients with chest wall disorders, neuromuscular disease, and chronic obstructive lung disease. NIPPV was used to simplify ventilatory management and assist the return of spontaneous breathing in patients with chronic respiratory insufficiency who had failed to wean from conventional intermittent positive pressure ventilation (IPPV). METHODS: A trial of NIPPV was carried out in 22 patients with weaning difficulties. Nine patients had chest wall disorders or primary lung disease, six had neuromuscular conditions, and seven had cardiac disorders with additional pulmonary disease. Conventional IPPV via an endotracheal tube or tracheostomy had been continued postoperatively in nine patients and 13 had been ventilated after acute cardiorespiratory decompensation. RESULTS: Conventional IPPV had been continued for a median of 31 days (range 2-219). Eighteen patients were successfully transferred to NIPPV and discharged home a median of 11 days (range 8-13) after starting this type of ventilation. Sixteen patients remain well 1-50 months after hospital discharge and 10 of these continue on domiciliary nocturnal NIPPV. Seven patients have returned to work. CONCLUSION: NIPPV can be used to facilitate the return of spontaneous breathing and to reduce the need for intensive care accommodation in patients with an acute exacerbation of chronic respiratory insufficiency that requires intubation and IPPV.

Adult↗
PubMed1990

Aerosol therapy in AIDS.

Pneumocystis carinii pneumonia (PCP) is the most common presenting symptom in patients with the acquired immunodeficiency syndrome (AIDS). Clinical trials have shown that inhaled pentamidine, delivered by nebulizer, is an effective prophylaxis for PCP in high-risk patients, and can be used to treat mild to moderate episodes. Side effects are minor, in marked contrast to the parenteral route of administration. The choice of nebulizer system will determine both alveolar delivery of pentamidine and the incidence of cough related to deposition of droplets on large conducting airways. Radioaerosol studies have suggested that optimum nebulizer systems for inhaled pentamidine deliver the majority of the aerosol mass in droplets smaller than 2 microns diameter, ideal for alveolar penetration.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Role of nocturnal hypoxaemia in the genesis of systemic hypertension.

Two groups of patients with nocturnal arterial oxygen desaturation were compared. The degree of nocturnal oxygen desaturation, as reflected by the percentage of total sleep time spent with an oxygen saturation less than 90 and 80%, was similar in patients with the obstructive sleep apnoea syndrome (OSAS) and in those with nocturnal hypoventilation (NH) secondary to restrictive chest wall disease. Systemic hypertension was present in 16 of the 24 OSAS patients but in only 6 of the 24 with NH (p less than 0.005). Multiple regression analysis demonstrated that this difference remained significant even after adjustment for age, sex, weight and history of smoking. It is likely that factors other than nocturnal hypoxaemia are important in the aetiology of systemic hypertension in patients with sleep-related breathing disorders.

Female↗
PubMed1990

Alveolar targeting of aerosol pentamidine. Toward a rational delivery system.

Nebulizer systems that deposit a high proportion of aerosolized pentamidine on large airways are likely to be associated with marked adverse side effects, which may lead to premature cessation of treatment. We have measured alveolar deposition and large airway-related side effects (e.g., cough, breathlessness, and effect on pulmonary function) after aerosolization of 150 mg pentamidine isethionate labeled with 99mTc-Sn-colloid. Nine patients with AIDS were studied using three nebulizer systems producing different droplet size profiles: the Acorn System 22, Respirgard II, and Respirgard II with the inspiratory baffle removed. Alveolar deposition was greatest and side effects least with the nebulizer producing the smallest droplet size profile (Respirgard II), whereas large airway-related side effects were prominent and alveolar deposition lowest with the nebulizer producing the largest droplet size (Acorn System 22). Values for alveolar deposition and adverse airway effects were intermediate using the Respirgard with inspiratory baffle removed, thus indicating the importance of the baffle valve in determining droplet size. Addition of a similar baffle valve to the Acorn System 22 produced a marked improvement in droplet size profile. Selection of a nebulizer that produces an optimal droplet size range offers the advantage of enhancing alveolar targeting of aerosolized pentamidine while reducing large airway-related side effects.

Acquired Immunodeficiency Syndrome↗
PubMed1989

The effect of intermittent positive-pressure hyperinflation in restrictive chest wall disease.

The effects of intermittent positive-pressure hyperinflation on lung volumes, arterial blood gas tensions and respiratory muscle performance have been assessed in 10 patients with severe scoliosis (vital capacity 22-43% predicted). Hyperinflation was carried out 2-3 times a day for 5 min aiming to double the spontaneous tidal volume with each delivered breath. A volume-preset, time-cycled device was used in 6 patients and a pressure-cycled, patient-triggered machine in 4 cases. Progressive reduction in lung volume was reversed by the volume-preset device which increased the mean vital capacity from 29 to 33% predicted after 3 months (p less than 0.05) with improvement maintained after 9 months. This machine offered a significant advantage over the pressure-cycled device which at maximum or near maximum inflation pressures produced less hyperinflation and had no beneficial effect on lung volumes. The improvement in vital capacity was correlated with the degree of hyperinflation (r = 0.65; p less than 0.05). The effect of hyperinflation on arterial blood gas tensions was transient and not accompanied by an increase in accessible alveolar volume.

Adult↗
PubMed1989

Effect of protriptyline on ventilatory responses to hypercapnia and asphyxia in normal subjects.

A double-blind crossover study was undertaken to assess the effect of protriptyline on ventilatory responses in normal subjects. Seven subjects received in random order placebo, 10 mg and 20 mg protriptyline daily for 2 weeks. Measurements of hypercapnic ventilatory response (HCVR) and asphyxial hypoxic ventilatory response (HVR) were made before treatment, 6-8 h after the first dose, and after 2 weeks treatment. Mean HCVR and HVR following 10 mg and 20 mg protriptyline did not differ significantly from measurements on placebo, neither for the single dose study or after 2 weeks.

Adult↗
PubMed1988

Use of negative pressure ventilation to facilitate the return of spontaneous ventilation.

Negative pressure ventilation was used to facilitate the return of spontaneous ventilation in 10 patients with severe, chronic respiratory disability. All patients had required tracheal intubation and intermittent positive pressure ventilation, and conventional weaning techniques had failed. Details of the method are described. It permits extubation before spontaneous ventilation can be sustained indefinitely and thus assists the return of normal speech, sleep pattern and nutrition. The lack of flexible control of ventilatory variables and absence of access to the trachea for sputum clearance limit its widespread application.

Adolescent↗