Management of chronic ventilatory insufficiency with electrical diaphragm pacing.

We have had experience with diaphragm pacing in 24 patients at the Toronto Western Hospital. Fourteen patients have undergone bilateral implants to treat chronic ventilatory insufficiency (CVI) caused by traumatic tetraplegia at the C1/2 level (eight patients), neurogenic apnea (five) and one case of neonatal apnea. Unilateral stimulators for nocturnal pacing have been implanted in five patients with central alveolar hypoventilation (sleep apnea) and five patients who suffered CVI resulting from various etiologies. Of the patients who were ventilatory dependent, 80% were successfully weaned and in the entire series, 58% of the patients are living. Diaphragm pacing was successful in 67%, partially successful in 8% and ineffective in 25%. The major complications were: death by pneumonia, failure of the radio receivers, and infection. Diaphragm pacing is the treatment of choice for patients who are ventilator dependent and tetraplegic from upper cervical trauma or in some cases of neurogenic apnea; it may be life saving for patients who suffer central alveolar hypoventilation.

Diaphragm pacing and continuous positive airway pressure.

The effect of changes in continuous positive airway pressure (CPAP) on the tidal volume generation by the diaphragm during electrical stimulation of the phrenic nerves in a quadriplegic patient is presented. Measurements of tidal volume, end-tidal PCO2, arterial PCO2, oxygen consumption, physiologic dead space to tidal volume ratio, diaphragm length, and thoracic and abdominal dimensions were made at values of CPAP from 0 to 20 cm H2O during periods of diaphragm pacing. Total respiratory compliance (TRC) was measured during controlled ventilation with incremental positive end-expiratory pressure (PEEP) from 0 to 20 cm H2O. A significant negative correlation was found between increasing CPAP and generated tidal volumes. This correlation was seen to occur even when TRC was constant at degrees of CPAP from 0 to 7.5 cm H2O. When phrenic nerve stimulation was commenced, oxygen consumption rose significantly from values obtained during controlled ventilation, but there was no significant correlation between changes in CPAP and the rise in oxygen consumption. Using inductance methods, thoracic and abdominal diameters were seen to rise as CPAP was increased. As suggested by the decrease in the length of the vertical and horizontal portions of the diaphragm in the chest roentgenogram, the conformation of the diaphragm also changed. It is suggested that the operating length and conformation of the diaphragm are principal factors affecting tidal volume generation during electrical stimulation of the phrenic nerves.

Effect of chest wall vibrations on pulmonary function in chronic bronchitis.

Manual chest wall vibration is one physiotherapeutic technique frequently employed in the management of respiratory disease. A clinical study was undertaken to examine the effects of manual chest wall vibrations on pulmonary function and arterial oxygen saturation in patients with chronic bronchitis. Twelve patients participated in a three-day experimental design where the factors of three different days and three different treatments were randomized and balanced. On one day, deep-breathing exercises were given; on another, deep-breathing exercises with vibrations; and on the remaining day, no treatment was given. Lung volumes were measured before and after each maneuver, and arterial oxygen saturation was monitored continuously. There was a significant decrease in the expiratory reserve volume (ERV) immediately following the deep-breathing exercises alone, which remained constant after the 15-minute rest period (p = 0.032). The remaining outcome parameters do not appear to be significantly affected. Chest wall vibrations do not decrease the ERV in patients with chronic bronchitis.

A comparison of three means of pressurized aerosol inhaler use.

The bronchodilator response to 200 micrograms of fenoterol hydrobromide using 3 different methods of inhalation from a pressurized aerosol metered-dose inhaler, was studied in 13 asthmatic patients. On 4 separate days and in random order, patients received either placebo aerosol or fenoterol aerosol delivered by the patients' own technique, delivered under supervision by a trained member of our staff, and delivered with a spacer device (Aerochamber) attached to the pressurized canister. There was no significant difference in the response to the 3 methods of active drug administration, but there was a significant difference (p less than 0.05) from the placebo control values. Thus, in this group of asthmatics the patients' own method of inhalation, using the standard dose of 200 micrograms of fenoterol from a pressurized aerosol metered-dose inhaler, appears to be as effective a means of bronchodilation as the other techniques used in this study.

Lung function in diaphragm pacing.

Electric stimulation of the diaphragm via the phrenic nerve to induce ventilation has recently been used for the long-term management of chronic ventilatory insufficiency. Since 1973 three patients with inadequate alveolar ventilation have been treated with diaphragm pacing at the Toronto Western Hospital. Two, who had quadriplegia due to lesions of the spinal cord in the upper cervical region and a severe restrictive ventilatory defect, were treated with continuous diaphragm pacing. The third patient required assisted nocturnal ventilation because of primary alveolar hypoventilation. All three patients tolerated the diaphragm pacing well, and pulmonary function tests showed satisfactory gas exchange with the patients breathing room air. This form of therapy seems to be a practical clinical method of managing chronic ventilatory failure in patients with lesions of the upper cervical cord or primary alveolar hypoventilation.

Survey of the clinical use of pressurized aerosol inhalers.

Questions as to the use of pressurized aerosol inhalers were asked of 130 persons presenting for routine pulmonary function studies who had used such a device in the previous year. After spirometry was conducted the subjects used the inhaler; they were unaware that their technique of use was being observed. Only 10.8% performed correctly all 11 maneuvers suggested for the proper use of the inhalers, and 24.7% failed to perform more than 5 satisfactorily. There were significant differences in performance according to referral diagnosis (chronic obstructive lung disease v. asthma) and regularity of use of inhalers.

Primary alveolar hypoventilation treated with nocturnal electrophrenic respiration.

A case of primary alveolar hypoventilation is described. Despite characteristic clinical findings, the diagnosis was delayed for 4 years. Alleviation of nocturnal hypoxemia and hypercapnia initially by a rocking bed and subsequently by phrenic nerve stimulation was accompanied by reversal of cor pulmonale and polycythemia. Electrophrenic respiration is an effective form of long-term management in primary alveolar hypoventilation.

A study of inhaled beclomethasone dipropionate therapy in asthma.

Fourteen patients with asthma have been followed in a long term clinical trial of the inhaled synthetic corticosteroid, beclomethasone dipropionate. All the patients were corticosteroid-dependent, with significant corticosteroid adverse effects. Twelve of the patients were able to stay on long term beclomethasone dipropionate therapy. Eight were able to discontinue use of systemic corticosteroids. There was a statistically significant reduction in the use of systemic corticosteroids (P<0.01) for the group when they were transferred to beclomethasone dipropionate. There was also an improvement of corticosteroid adverse effects in ten patients, but no significant change in their symptom scores. Several points of caution are stressed concerning long term clinical use of this promising drug.

Immunofluorescent staining of lung biopsy in fibrosing alveolitis.

There is a group of lung diseases, as yet of unknown cause, which are characterized by a pathologic picture of alveolar wall fibrosis with an intra-alveolar exudate containing large cells. A case is reported with this clinicopathological picture in which immunofluorescent studies of the biopsied lung tissue revealed no tissue-bound immunoglobulins, complement component (beta(1) C) or fibrinogen. The literature on the immunofluorescent studies of biopsied lung tissue in this group of lung diseases is reviewed. The reports are scant and varied, making it impossible to conclude that autoallergic mechanisms are solely responsible as the pathogenetic mechanism in this group of lung diseases.