The effect of theophylline with ethylenediamine (aminophylline) on cerebral hemodynamics in the presence of cardiac failure with and without Cheyne-Stokes respiration

Cheyne-Stokes respiration in congestive heart failure

Cheyne-Stokes respiration is an abnormal breathing pattern which commonly occurs in patients with decompensated congestive heart failure and neurologic diseases, in whom periods of tachypnea and hyperpnea alternate with periods of apnea. In the majority of these patients, the ventilatory patterns may not be recognized, and the clinical features are generally dominated by the underlying disease process. Cheyne-Stokes respiration may, however, have profound effects on the cardiopulmonary system, causing oxygen desaturation, cardiac arrhythmias, and changes in mental status. Treatment of Cheyne-Stokes respiration in congestive heart failure with supplemental oxygen or nasal continuous positive airway pressure, in addition to conventional therapy, may improve the overall cardiac function and perhaps the patient's prognosis.

Cheyne-Stokes respiration presenting as sleep apnea syndrome. Clinical and polysomnographic features

This study reports polysomnographic features of five patients with Cheyne-Stokes respiration (CSR). They were referred for evaluation of presumptive sleep apnea syndrome on the basis of history and physical examination, but were found to have predominantly CSR on all-night sleep study. On the initial polysomnographic study, CSR comprised 47 to 86% of all disordered-breathing events. Cheyne-Stokes respiration resulted in considerable oxyhemoglobin desaturation (mean baseline saturation was 95 +/- 4 +/- SD, and lowest saturation was 76 +/- 8). More than one-half of all CSR events resulted in awakenings or arousals. Evidence of upper airway obstruction was noted in the majority of CSR events in three of five patients. Four patients were treated with theophylline; one who refused drug therapy was treated with nasal continuous positive airway pressure (CPAP). Comparison of sleep studies before and after therapy showed a significant decrease in the CSR index (29 +/- 11 versus 2 +/- 2) and in the maximal oxyhemoglobin desaturation associated with CSR (13 +/- 5 versus 3 +/- 2), and an improvement in lowest O2 saturation associated with CSR (76 +/- 8 versus 91 +/- 4). Total disruptions in sleep architecture per hour of sleep improved significantly with therapy (46 +/- 21 versus 20 +/- 8). We conclude that the clinical presentation of CSR can be indistinguishable from that of the "traditional" sleep apnea hypopnea syndrome and can result in major oxyhemoglobin desaturation and sleep fragmentation. Theophylline results in considerable improvement in the disordered breathing of CSR during sleep.

Psychiatric aspects of congestive heart failure: implications for consulting psychiatrists

Abnormalities of mental function are common problems in patients with congestive heart failure, a problem that is often referred to the consulting psychiatrist. These abnormalities become more frequent and more serious as failure of the heart progresses and they can exhibit a wide variety of manifestations. Cardiac output and cerebral blood flow are preserved due to compensatory mechanisms in mild heart failure but can be severely compromised in advanced failure. Drugs used to treat heart failure, especially digitalis, can produce a wide variety of mental aberrations including delirium, usually when these drugs are used in excess. Diuretics can produce electrolyte abnormalities resulting in mental derangements and vasodilator therapy can produce hypotension. Psychotropic drugs are well recognized as having significant cardiovascular effects that need to be considered when these agents are applied to the cardiac patient. Antidepressant and antipsychotic drugs have anticholinergic, antiadrenergic and quinidine-like effects that can produce further cardiac decompensation in heart failure. Antidepressants are generally well tolerated except when toxic levels occur or in the most extremely compromised cardiac patients. Monoamine oxidase inhibitors should be used only in highly reliable patients to avoid the acute hypertensive crises that are well known to occur with these agents. Antipsychotic drugs with limited cardiovascular side effects can be used effectively and safely but care must be taken to avoid toxic levels which could produce excess hypotension or lethal arrhythmias. Lithium can also be used in heart failure if patients are effectively monitored to avoid toxic levels which could occur due to reduction in renal function, use of diuretics or imposition of a low sodium chloride diet. Evaluation and management of patients with mental symptoms and heart failure provides a strong challenge for the consulting psychiatrist.

Methylxanthines: toxicity to humans. 3. Theobromine, paraxanthine and the combined effects of methylxanthines

This review provides a brief overview of known information on the human toxicity of theobromine and paraxanthine. Theobromine has some pharmacological effects, although these activities are considerably weaker than those of theophylline and/or caffeine, described in parts 1 and 2 of this series (Stavric, Fd Chem. Toxic. 1988, 26, 541 & 645). Paraxanthine, which is not found in plants or foods, is the major metabolite of caffeine in humans, in whom its toxicological potency appears to be very low. This paper gives a brief retrospective view of possible toxicological effects when methylxanthines are taken simultaneously or are present in combination as a result of metabolic transformation. Critical review of toxic manifestations due to exposure to relatively large doses of caffeine and theophylline indicates that such combined exposure may potentiate the toxic effects of either drug.

Mechanism of respiratory effects of methylxanthines

Neural respiratory responses to theophylline, aminophylline and ethylenediamine were determined in paralyzed, vagotomized and glomectomized cats whose end-tidal PCO2 and brain temperature were kept constant. Intravenous theophylline and aminophylline similarly stimulated respiration, but ethylenediamine had no effect. The following did not cause the response: muscular and mechanical factors, carotid body and vagal reflexes, spinally mediated mechanisms arising below C7, changes of arterial PCO2 or medullary ECF pH, changes of whole body metabolic rate or release of substances from the adrenal glands. Absence of suprapontine brain did not prevent the response. Pretreatment with a serotonin antagonist did not affect the response but two different dopamine antagonists caused its attenuation. When administered into the third ventricle, theophylline did not stimulate respiration, but both aminophylline and ethylenediamine, due to the latter's ability to mimic the inhibitory effects on neurons of gamma-aminobutyric acid (GABA), caused significant depression of respiration. We conclude that the neural respiratory response to systemically administered theophylline is mediated at the level of the brainstem, and somehow involves the action of the neurochemical dopamine. The failure of cerebroventricularly administered theophylline to stimulate respiration must be related to its inability to reach the appropriate neurons from the cerebrospinal fluid.

Ventilatory dysfunction resulting from bilateral anterolateral high cervical cordotomy. Dual beneficial effect of aminophylline

Because of metastatic pain resistant to medical treatment after left pneumonectomy for squamous cell carcinoma, a 46-year-old patient underwent a bilateral cervical cordotomy at the C1-C2 anterolateral level, in two phases. The second intervention was followed by severe ventilatory problems requiring mechanical ventilation, and at a later stage, the implantation of a phrenic pacemaker on the right side. Analysis of the ventilatory pattern during spontaneous breathing and during phrenic pacing and measurement of the transdiaphragmatic pressure during phrenic nerve stimulation revealed the existence of a beneficial effect of aminophylline on both the regulation of ventilation and diaphragmatic contractility.

Paroxysmal nocturnal dyspnoea and periodic respiration

Patterns of breathing at night were recorded in 4 patients with heart-failure. 2 had periodic breathing while awake and in 2 it developed after they fell asleep. In all 4 the phase of hyperventilation disturbed sleep. These cases also illustrate other problems caused by periodic respiration in heart-failure, which range from tiredness during the day to an inability to sleep for more than a few minutes. Nocturnal waking in the hyperventilation phase of Cheyne-Stokes breathing should be differentiated from paroxysmal nocturnal dyspnoea caused by episodes of pulmonary oedema at night.

Experimentally induced Cheyne-Stokes breathing

We have studied the propensity for periodic breathing to occur in cats anaesthetized with pentobarbitone breathing either spontaneously or with the aid of a 'servo-respirator' governed continuously by the efferent phrenic nerve activity. Sustained periodic breathing could be induced increasing 'controller gain', either by increasing the gain of the respirator, or by lung deflation, which reflexly increased controller responses to both hypoxia and hypercapnia. Periodic breathing was potentiated both by hypoxia and by diminishing the central (CO2, H+)-drive by focal cooling at the ventral surface of the medulla, two procedures which increase the relative influence of hypoxic drive. Less hypoxia was needed to produce periodic breathing at high rather than low controller gains. Reducing controller gain to zero by constant artificial respiration always abolished periodic breathing. Periodic breathing was also eradicated when the relative importance of CO2 drive was enhanced by breathing the cats with CO2-enriched gas mixtures or with 100% O2. The results are consistent with theoretical predictions for the occurrence of oscillations in the mechanisms for the chemical control of breathing and indicate that increasing controller gas can produce periodic breathing. The results further emphasize the importance of the (CO2, H+)-drive in preserving ventilatory stability.

Aminophylline increases cerebral metabolic rate and decreases anoxic survival in young mice

In weanling mice treated with pharmacologic doses of aminophylline, the concentrations of adenosine 3',5'-monophosphate and guanosine 3',5'-monophosphate in the brain increased 44 and 36 percent, respectively, and the cerebral metabolic rate was three times that in controls. In neonatal mice, therapeutic doses of aminophylline greatly decreased the rate of anoxic survival in vivo and the duration of gasping of the isolated head. The findings suggest caution in the use of this drug and other methylxanthines in hypoxic human newborns.

Physiologic changes induced by theophylline in the treatment of apnea in preterm infants

Ten preterm infants (birth weight 0.970 to 2.495 kg) with apnea due to periodic breathing (apneic interval = 5 to 10 seconds) or with "serious apnea" (greater than or equal to 20 seconds) were studied before and after the administration of theophylline. We determined the incidence of apnea, respiratory minute volume, alveolar gases, arterial gases and pH, "specific" compliance, functional residual capacity, and work of breathing. Theophylline decreased the incidence of apnea (P less than .05), increased respiratory minute volume (P less than 0.001), decreased (PACO2 (and PaCO2 P less than 0.001), increased the slope of the CO2 response curve (P less than 0.02) with a significant shift to the left (P less than 0.02). These findings suggest that the decreased incidence of apnea after theophylline is associated with an increase in alveolar ventilation and increased sensitivity to CO2 with a pronounced shift of the CO2 response curve to the left. These data are consistent with the idea that apnea is a reflection of a depressed respiratory system.

RA 642, a pyrimido-pyrimidine-derivative with vasodilating and hypertensive potency

2,2'-[(4,8-bis(diethylamino)-pyrimido[5,4-d]-pyrimidine-2,6-diyl)di-(2-methoxyethyl)imino]diethanol), RA 642, combines hypertensive and vasodilating effects. In anaesthetized animals arterial blood pressure was increased by i.v. doses of 0.25-4 mg/kg in cats and 0.025-0.25 mg/kg in dogs. In conscious dogs, 25 mm increase of mean blood pressure was achieved with 0.2 mg/kg i.v. and 18.8 mg/kg p.o. Cerebral blood flow was enhanced and calculated cerebral vascular resistance was reduced by RA 642. Total peripheral resistance was diminished by 0.25-1.0 mg/kg i.v. A vasodilatation of femoral and coronary vessels was shown after intraarterial injection. This effect as well as a BaCl2-antagonism in the isolation ileum is explained by a papaverine-like relaxant effect on smooth muscle. Activity on peripheral adrenergic receptors was excluded. Hypertension was abolished in spinalized cats, indicating a central mechanism of this effect.

Cheyne-Stokes respiration: an oximeter study

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A comparison of the cerebral hemodynamic response to aramine and norepinephrine in the normotensive and hypotensive subject

Previous observations have demonstrated a depression in cerebral blood flow during controlled hypotension with ganglionic blocking agents. Cerebral blood flow is also decreased when normotensive individuals are made hypertensive by the administration of vasopressor agents. The opposite response is observed when hypotensive individuals are made normotensive by the administration of these same agents, in which circumstance cerebral blood flow is increased.

Studies of the cerebral circulation and metabolism in congestive heart failure

In a study of the cerebral circulation and metabolism in congestive heart failure, using Kety's nitrous oxide technic, it was found that no significant alterations of the cerebral circulation were present when the quantities measured were compared with values determined for a control group. A decrease in cerebral blood flow and oxygen consumption below values established for normal young individuals was demonstrated to be secondary to the presence of arteriosclerosis and not to cardiac decompensation as had previously been concluded. It was also found that in the series studied the increased venous and cerebrospinal fluid pressures were not of sufficient magnitude to affect the cerebral circulation. The factor of a decreased arterial carbon dioxide tension as a cause for diminished cerebral blood flow in cardiac decompensation was similarly considered and dismissed.