C Co om mp pa ar ri is so on n o of f c ce er rv vi ic ca al l m ma ag gn ne et ti ic c s st ti im mu ul la at ti io on n a an nd d b bi il la at te er ra al l p pe er rc cu ut ta an ne eo ou us s e el le ec ct tr ri ic ca al l s st ti im mu ul la at ti io on n o of f t th he e p ph hr re en ni ic c n ne er rv ve es s i in n n no or rm ma al l s su ub bj je ec ct ts s We compared cervical magnetic stimulation with conventional supramaximal bilateral percutaneous electrical stimulation in nine normal subjects. We measured oesophageal pressure (Poes), gastric pressure (Pgas) and transdiaphragmatic pressure (Pdi). The maximal relaxation rate (MRR) was also measured. The mean magnetic twitch Pdi was 36.5 cmH 2 O (range 27-48 cmH 2 O), significantly larger than electrical twitch Pdi, mean 29.7 cmH 2 O (range 22-40 cmH 2 O).The difference in twitch Pdi was explained entirely by twitch Poes, and it is possible that the magnetic technique stimulates some of the nerves to the upper chest wall muscles as well as the phrenic nerves. We compared bilateral, rectified, integrated, diaphragm surface electromyographic (EMG) responses in three subjects and found results within 10% in each subject, indicating similar diaphragmatic activation. The within occasion coefficient of variation, i.e. same subject/same session, was 6.7% both for magnetic and electrical twitch Pdi. The between occasion coefficient of variation, i.e. same subject/different days, was 6.6% for magnetic stimulation and 8.8% for electrical. There was no difference between relaxation rates measured with either technique.We conclude that magnetic stimulation is a reproducible and acceptable technique for stimulating the phrenic nerves, and that it provides a potentially useful alternative to conventional electrical stimulation as a nonvolitional test of diaphragm strength.

We report 16 adult men (age, 41 to 75 yr) with neuralgic amyotrophy (NA) who presented with dyspnea due to involvement of the diaphragm. All patients developed breathlessness after a prodrome of acute severe neck and shoulder pain. Bilateral diaphragm paralysis (BDP) was confirmed in 12 patients and unilateral diaphragm paralysis (UDP) in four by the absence of electrical and mechanical responses to percutaneous phrenic nerve stimulation. Global expiratory muscle strength was well preserved in all patients, but inspiratory muscle strength was reduced in proportion to the extent of diaphragmatic involvement. Lung function showed low lung volumes with preservation of carbon monoxide transfer coefficient in all patients. Two BDP patients were hypoxic (PaO2 = 67 and 54 mm Hg, respectively) on daytime arterial blood gas analysis; the latter patient with pre-existing chronic obstructive pulmonary disease and marked obesity also had borderline hypercapnia (PaO2 = 49 mm Hg). Overnight sleep studies in three BDP and two UDP patients showed frequent intermittent arterial oxygen desaturations apparently caused by obstructive sleep apneas, but there was no evidence of alveolar hypoventilation. Follow-up muscle studies in five BDP and four UDP patients between 2 and 4 yr after initial referral showed complete recovery of diaphragmatic function in only two UDP patients, one of whom relapsed a year later. We postulate that NA may be an important but underrecognized cause of diaphragmatic paralysis in otherwise normal patients. Diaphragmatic strength returns very slowly, if at all.

Summary

The effect of the combination fenoterol-ipratropium bromide (Duovent) as a bronchodilator drug versus salbutamol and placebo was investigated in 20 patients with chronic obstructive lung disease in a random cross-over trial. Our study was performed not only to evaluate the bronchodilator response, but especially to quantify the possibly more prolonged action of Duovent versus salbutamol, based on registration of prevention of asthma attacks, time effects and protective activity, management and tolerance. Each patient received therapy for 3 weeks; in each week only one of the preparations: salbutamol, Duovent or placebo was used. Respiratory function tests were determined every week on the 3rd, 5th and 7th days at the same time exactly at 30 and 60 min after drug inhalation. Additionally we registered, for each patient, daily symptomatology (e.g., asthma attacks, cough, additional daily puff use, adverse reactions) by using a personal clinical diary.The results and analysis of the pulmonary tests (especially FEVi and peak expiratory flow) confirmed the bronchodilator effect of both drugs, higher for Duovent but not sufficient to reach statistical significance. Clinical condition, regarding number, severity of asthma crises and additional puff use, showed a significant statistical variation for each symptom either as regards advantage of Duovent and salbutamol versus placebo, or advantage of Duovent versus salbutamol. Therefore, the results of this trial reveal an excellent bronchodilator effect of both drugs and confirm a higher clinical efficacy of Duovent if used in long-term treatment, with good tolerability.