Respiratory stimulants, COPD

Unlabeled Uses Urine alkalinization, respiratory stimulant in COPD... 

There is no role for respiratory stimulants in the long-term management of COPD. Agents that have shown some utility in the acute setting include amiltrine and doxapram. However, amiltrine is available only in Europe, and its usefulness is limited by neurotoxicity. Doxapram is available for intravenous use only and may be no better than intermittent NPPV. 

This xanthine derivative is an only a modest bron-chodilator in COPD, and because of its narrow therapeutic range, frequently seen adverse effect and drug interactions, it is becoming less frequently used, some patients experience side effects even within the therapeutic range. The non-bronchodilator effects of theophylline such as systemic and pulmonary vascular dilatation, central nervous system stimulation, improvement of the strength and effectiveness of respiratory muscles and possibly anti-inflammatory effects are of disputed clinical significance at usual therapeutic levels. 

Doxapram is an analeptic that increases the depth of respirations (tidal volume) by stimulating the respiratory center in CNS respiratory rate may increase slightly. It may elevate BP by increasing cardiac output. Respiratory depression from opiates is reversed without affecting pain relief. It is indicated when one requires the stimulation of deep breathing in postoperative patients for reversal of respiratory depression caused by anesthesia (other than muscle relaxants) or drug overdose and as a temporary measure in acute respiratory failure in patients with chronic obstructive pulmonary disease (COPD) who are not undergoing mechanical ventilation. 

In healthy volunteers, stimulation of the phrenic nerves elicits twitch pressures of 31 to 39 cmH20, whereas in patients with severe COPD, twitch pressures average 19 to 20 cmH20 (53,60). Twitch pressures in patients recovering from an episode of acute respiratory failure are about half of those recorded in ambulatory patients with severe COPD (Fig. 5) (59,61,62). This decrease is in keeping with respiratory muscle weakness in most of these patients. Respiratory muscle weakness in mechanically ventilated patients can result from preexisting conditions or from new-onset conditions (63). 

Abbreviations-. TCEMS, transcutaneous electrical muscle stimulation CHF, congestive heart failure COPD, chronic obstructive pulmonary disease Vo2max, peak oxygen consumption NYHA, New York heart association CSA, cross-sectional area Wmax, maximal workload CRQ, chronic respiratory disease questionnaire. 

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