Theophylline improves measurements of respiratory muscle efficiency

Aminophylline increases parasternal muscle action in awake canines

The traditional theophylline bronchodilator, aminophylline, is still widely used, especially in the treatment of COPD. The effects of aminophylline on ventilation and action of the costal diaphragm have been previously defined, but other respiratory muscles - notably the chest wall, are not well determined. Therefore, we investigated the effects of aminophylline on the Parasternal intercostal, a key obligatory inspiratory muscle, examining muscle length, shortening and EMG. We studied 11 awake canines, chronically implanted with sonomicrometer crystals and fine-wire EMG electrodes in the parasternal muscle. Ventilatory parameters, muscle length (shortening), and moving average muscle EMG activity, were measured at baseline and with aminophylline, during resting and hypercapnic stimulated breathing. Experiments were carried out prior to administration of aminophylline (baseline), and 1.5 h after loading and ongoing infusion. Minute ventilation, tidal volume and respiratory frequency all increased significantly with aminophylline, both during resting breathing and at equivalent levels of hypercapnic stimulated breathing. Parasternal baseline muscle length was entirely unchanged with aminophylline. Parasternal shortening increased significantly with aminophylline while corresponding parasternal EMG activity remained constant, consistent with increased contractility. Thus, in awake, intact mammals, aminophylline, in the usual therapeutic range, elicits increased ventilation and increased contractility of all primary inspiratory respiratory muscles, including both chest wall and diaphragm.

Use of theophylline in chronic obstructive pulmonary disease: examining the evidence

PURPOSE OF REVIEW

The role of theophylline in the management of chronic obstructive pulmonary disease remains controversial. This review was undertaken to determine the efficacy of theophylline in patients with stable disease.

RECENT FINDINGS

Twenty-two good quality randomized controlled trials were included in this systematic review. The review showed that theophylline significantly improved forced expiratory volume in 1 s and forced vital capacity (weighted mean difference 0.10 L; 95% confidence interval 0.04-0.16 and weighted mean difference 0.21 L; 95% confidence interval 0.10-0.31, respectively). V also improved with theophylline (weighted mean difference 195.27 mL/min; 95% confidence interval 112.71-277.83), as did Pa and Pa (weighted mean difference 1.45 mmHg; 95% confidence interval 0.26-2.65 and weighted mean difference -1.09 mmHg; 95% confidence interval -1.83 to -0.35, respectively). Patients preferred theophylline over placebo (relative risk 2.27; 95% confidence interval 1.26-4.11). Theophylline increased the risk of nausea, however, compared with placebo (relative risk 7.67; 95% confidence interval 1.47-39.94).

SUMMARY

This review has shown that oral theophylline plays an important role in the management of patients with stable chronic obstructive pulmonary disease by improving lung function, arterial blood gas tensions and ventilatory capacity. Patients also preferred treatment with theophylline when compared with placebo. The benefits of theophylline in stable chronic obstructive pulmonary disease, however, have to be weighed against the risk of adverse effects, particularly nausea.

Effect of acute aminophylline administration on diaphragm function in high cervical tetraplegia: a case report

Theophylline has been shown to have beneficial effects on phrenic nerve and diaphragm activation. This case report involves a C5-C6 chronic tetraplegic patient with acute respiratory failure and ventilator dependence. IV aminophylline was administered in increasing doses (2 mg/kg, 4 mg/kg, and 6 mg/kg) over the course of 1 day. Diaphragm surface electromyography (sEMG), measures of respiration (tidal volume, minute ventilation, and frequency), and serum theophylline levels were captured. Diaphragm sEMG activity increased by a maximum of 50% at therapeutic levels. The rapid shallow breathing index dropped from 112 to 86. The subject was successfully weaned from ventilatory support. We conclude that administration of aminophylline facilitated weaning from ventilatory support in this tetraplegic patient.

Efficacy of theophylline in people with stable chronic obstructive pulmonary disease: a systematic review and meta-analysis

OBJECTIVES

To determine the efficacy of oral theophylline compared with placebo in people with stable chronic obstructive pulmonary disease (COPD).

METHODS

Systematic review of randomized-controlled trials comparing oral theophylline with placebo for a minimum of 7 days in people with stable COPD.

RESULTS

Twenty randomized-controlled trials were included in this review. The following outcomes showed significant improvement with theophylline compared with placebo: FEV1 and FVC both improved with theophylline (weighted mean difference [WMD] 0.10 L; 95% confidence interval [95% CI] 0.04-0.16 and WMD 0.21 L; 95% CI 0.10-0.32, respectively). VO2 max also improved with theophylline (WMD 195.27mL/ min; 95% CI 112.71-277.83), as did PaO2 and PaCO2 (WMD 3.18 mmHg; 95% CI 1.23-5.13 and WMD -2.36mmHg; 95% CI -3.52 to -1.21, respectively). Patients preferred theophylline over placebo (relative risk 2.27; 95% CI 1.26-4.11). Theophylline increased the risk of nausea compared with placebo (RR 7.67; 95% CI 1.47-39.94).

CONCLUSION

This review has shown that theophylline still has a role in the management of stable COPD, and is preferred by patients over placebo. However, the benefits of theophylline in stable COPD have to be weighed against the risk of adverse effects.

Oral theophylline for chronic obstructive pulmonary disease

BACKGROUND

Oral theophylline has, for many years, been used as a bronchodilator in patients with COPD. Despite the introduction of new drugs, and its narrow therapeutic index, theophylline is still recommended for COPD treatment.

OBJECTIVES

To determine the effectiveness of oral theophylline when compared to placebo in patients with stable COPD.

SEARCH STRATEGY

The Cochrane Airways Review Group and Cochrane Controlled Clinical Registers were searched.

SELECTION CRITERIA

All studies were randomised controlled trials (RCTs).

DATA COLLECTION AND ANALYSIS

Data were independently abstracted and the methodological quality assessed by two reviewers.

MAIN RESULTS

Twenty RCTs met the inclusion criteria. Concomitant therapy varied from none to any other bronchodilator plus corticosteroid (oral and inhaled). The following outcomes were significantly different when compared to placebo. FEV1 improved with treatment: Weighted Mean Difference (WMD) 100 ml; 95% Confidence Interval (95%CI) 40, 160 ml. Similarly for FVC: WMD 210 ml 95%CI 100, 320. Two studies reported an improvement in VO2max; WMD 195 ml/min, 95%CI 113,27). At rest, PaO2 and PaCO2 both improved with treatment (WMD 3.2 mmHg; 95%CI = 1.2, 5., and WMD -2.4 mmHg; 95%CI = -3.5, -1.2, respectively). Walking distance tests did not improve (4 studies, Standardised Mean Difference 0.30, 95%CI -0.01, 0.62), neither did Visual Analogue Score for breathlessness isn two small studies (WMD 3.6, 95%CI -4.6, 11.8). The Relative Risk (RR) of nausea was greater with theophylline (RR 7.7; 95%CI 1.5, 39.9). However, patients' preference for theophylline was greater than that for placebo (RR 2.27; 95%CI = 1.26, 4.11). Very few patient withdrew from these studies for any reason.

REVIEWER'S CONCLUSIONS

Theophylline has a modest effect on FEV1 and FVC and slightly improves arterial blood gas tensions in moderate to severe COPD. These benefits were seen in patients receiving a variety of different concomitant therapies. Improvement in exercise performance depended on the method of testing. There was a very low dropout rate in the studies that could be included in this review, which suggests that recruited patients may have been known by the investigators to be theophylline tolerant. This may limit the generalisability of these studies.

The effect of theophylline on apnoea and hypoxaemic episodes in the premature neonate during the 1st 3 days after birth

Although the effect of theophylline on apnoea is well documented, its influence on hypoxaemic episodes in premature neonates is less well known. To investigate the influence of the drug on both parameters, 37 apnoeic neonates were monitored before and after theophylline treatment. Incidents and densities of pathological apnoea (cessation of nasal airflow > or = 20 seconds) were recorded. A fall of > or = 10% for > 10 seconds in peripheral oxygen saturation was classified as a hypoxaemic episode. Ethical constraints precluded the inclusion of a control group. Each infant served as its own control. Theophylline serum concentrations were 5.6 (3.4), 8 (7.1) and 8 (5.3) mg/l on days 1, 2 and 3, respectively. The apnoea incidents and densities decreased significantly (p = 0.0001) from baseline on all 3 days. The total number of hypoxaemic episodes, as well as those not associated with pathological apnoea, decreased, though not significantly. However, those hypoxaemic episodes associated with pathological apnoea and a fall in pulse rate of > or = 20% decreased significantly from baseline on day 2 only. Throughout the study period, over 80% of hypoxaemic episodes were not associated with apnoea. It is concluded that in the doses used, theophylline was more effective in reducing apnoea than hypoxaemic episodes in premature neonates.