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Biomedical subjects

O Marrone

Publications and source records attributed to O Marrone.

12 recordsLinked to original sources
PubMed1992

Acute effects of oxygen administration on transmural pulmonary artery pressure in obstructive sleep apnea.

In order to investigate the role of hypoxia on the cyclic oscillation of transmural pulmonary artery pressure (PAP) in obstructive sleep apnea, oxygen was administered during one half of the night to six patients affected by obstructive sleep apnea syndrome during a nocturnal polysomnographic study. In each patient, transmural PAP measurements were performed on 15 randomly selected apneas recorded while breathing room air, and on 15 during O2 administration. During O2 administration in all patients, apneas were associated with a higher oxyhemoglobin saturation (SaO2), a smaller SaO2 swing, and a higher transcutaneous PCO2. The mean highest level of transmural PAP in the apneic episodes, commonly reached at their end, was significantly lower than while breathing room air in only two patients; however, due to a decrease in the mean lowest PAP level (at the beginning of apneas), the extent of the PAP increase within apneas did not differ between air and O2 breathing; these patients showed the smallest increase in transcutaneous PCO2 in our sample. End-apneic transmural PAP during O2 administration was significantly higher in one subject (for systolic values) and was not significantly different in the remaining three subjects. The extent of the increase in transmural PAP within apneas was greater in one patient; it was smaller in another one, but only for the diastolic values; and it did not differ significantly with respect to the value observed while breathing room air in all of the other subjects. The results suggest that hypoxia in obstructive apneas, at least in some patients, may lead to a steady increase in PAP, detectable both at the beginning and at the end of the episodes; conversely, the increase in PAP within apneas does not seem to be influenced by the simultaneous decrease in SaO2.

Air↗
PubMed1991

Occurrence of breathing disorders during CPAP administration in obstructive sleep apnoea syndrome.

The spectrum of breathing events during sleep in patients with obstructive sleep apnoea syndrome (OSAS) after the abolition of obstructive apnoeas has been extensively studied in tracheostomized patients, but has received much less attention in patients submitted to continuous positive airway pressure (CPAP). We analysed the breathing pattern during sleep in forty patients while CPAP was administered. A regular breathing pattern throughout the sleep study was observed in 15 patients. In the remaining 25 subjects, one or more of the following events was observed: central apnoeas, hypopnoeas, periodic breathing, prolonged oxyhaemoglobin desaturations. Central apnoeas during non-rapid eye movement (NREM) sleep appeared almost exclusively after arousals or wakefulness periods; their prevalence did not significantly differ between subjects who showed and who did not show similar events before CPAP. Central apnoeas in rapid eye movement (REM) sleep had a random occurrence. Hypopnoeas were found only in REM sleep, and, like central apnoeas, occurred randomly; in one patient they had a prolonged duration (up to 110 s). Periodic breathing was observed in only two subjects, one of whom had congestive heart failure: it was limited to NREM sleep and was not associated with arousals or shifts in sleep stage. Prolonged oxyhaemoglobin desaturations were found mainly in REM sleep; most subjects with such abnormalities had daytime blood gas alterations. In conclusion, abnormalities of the breathing pattern of patients with OSAS can be observed during CPAP and after tracheostomy, but periodic breathing is less common than is reported after tracheostomy, and is probably caused by different mechanisms.

Female↗
PubMed1990

Expiratory timing in obstructive sleep apnoeas.

Diaphragmatic electromyogram was recorded during NREM sleep in 4 patients affected by obstructive sleep apnoea (OSA) syndrome in order to evaluate the behaviour of expiratory time (TE) in the course of the obstructive apnoea-ventilation cycle. The two components of TE, i.e. time of post-inspiratory inspiratory activity (TPIIA) and time of expiratory phase 2 (TE2) were separately analysed. TPIIA showed a short duration, with only minor variations, within the apnoea, while its duration was more variable and longer in the interapnoeic periods: the longest TPIIA values were associated with the highest inspiratory volumes in the same breaths. This behaviour seemed regulated according to the need of a more or less effective expiratory flow braking, probably as a result of pulmonary stretch receptors discharge. Conversely TE2 showed a continuous gradual modulation, progressively increasing in the pre-apnoeic period, decreasing during the apnoea and increasing in the post-apnoeic period: these TE2 variations seemed related to oscillations in chemical drive. These data show that TE in the obstructive apnoea-ventilation cycle results from a different modulation in its two components and suggest that both mechanical and chemical influences play a role in its overall duration.

Adult↗
PubMed1989

Transmural pressure measurements. Importance in the assessment of pulmonary hypertension in obstructive sleep apneas.

Seven patients with OSAS were studied during nocturnal sleep in order to assess the trend of PAP throughout apneas and to identify factors possibly associated with such a trend. All patients underwent a polysomnography including the monitoring of PAP and esophageal pressure. While intravascular PAP decreased during apneas and increased at the resumption of breathing, transmural PAP values (ie, corrected for intrathoracic pressure swings) showed a trend toward a progressive increase throughout apneas and toward a decrease once ventilation had been resumed. The measurement of transmural values allowed a reliable assessment of PAP changes occurring during apneas, and different degrees of such changes shown by different patients may be related to a host of factors relevant to wakefulness and sleep, including individual responsivity to hypoxic stimulus.

Adult↗
PubMed1987

Continuous positive airway pressure improves the quality of sleep and oxygenation in obstructive sleep apnea syndrome.

We tested the effects of continuous positive airway pressure (CPAP) in 8 patients with obstructive sleep apnea syndrome (OSAS). The comparison of a nocturnal polygraphic study performed during spontaneous breathing with a study during CPAP administration performed the following night showed a significant reduction in stage 1 and increase in REM, the abolition of obstructive apneas and a significant increase in mean oxyhemoglobin saturation. Most patients reported marked relief of symptoms after the first night of treatment. However 3 patients, though confirming the improvement refused further CPAP. We conclude that CPAP is an effective measure for prevention of apneas in OSAS and that in compliant patients it may be regarded as a short-term measure when a permanent correction of the causes is planned, or as a long-term treatment when the latter is not feasible.

Aged↗
PubMed1986

Effects of almitrine bismesylate on nocturnal hypoxemia in patients with chronic bronchitis and obesity.

In a double-blind placebo controlled randomised study, the effects of almitrine bismesylate on the sleep induced Hb desaturations, associated or not with disorders of breathing, were tested. Patients (37-75 yrs, 8M and 2F) were affected by chronic bronchitis (out of any exacerbation) and obesity (weight excess at least 20%). They were known to have at least one nocturnal episode of hypoxemia (SaO2 fall higher or equal to 10%) with respect to the wakefulness level. Patients received either placebo or almitrine (1.5 mg/Kg/day) for 18 days and nocturnal polysomnography was performed both before and the last day of treatment. Almitrine induced an increase in PaO2 during wakefulness (p less than .05), an increase in mean SaO2 during sleep (p less than .01) and a decrease in the quantity of desaturation (Qd) during sleep, defined as the product of the mean desaturation by the duration of the episodes of desaturation (p less than .025). No clear effect could be observed either on the mean duration of the sleep disordered breathing (SDB) events or on their frequency whereas the desaturations due to them had a decrease.

Adult↗
PubMedDate not supplied

Obesity as a possible cause of respiratory failure in bilateral diaphragmatic paralysis. Case report.

An obese woman with respiratory failure and bilateral diaphragmatic paralysis, was studied in order to investigate the effects of weight loss on respiratory function during wakefulness and sleep. The patient was studied on 5 different occasions during which diurnal blood gas analysis, spirometry, CO2 rebreathing test, nitrogen wash-out test and a nocturnal polysomnographic study were performed. The follow-up period lasted 9 months, during which the patient progressively lost 19 kg. Progressive improvement in awake blood gas tensions (PaO2 + 21 mmHg, PaCO2 - 16 mmHg) as well as in nocturnal oxyhemoglobin saturation and transcutaneous PCO2 were observed; at the same time only minor changes in responsiveness to CO2 and in lung volumes were found. Conversely alveolar efficiency for CO2, obtained with the nitrogen wash-out test, in the supine posture increased from 81.7 to 90.5%, indicating an improvement in ventilation/perfusion ratio as a possible determinant of blood gas tension improvement during wakefulness and, as a consequence, also during sleep. We conclude that obesity is one possible cause of the occurrence of respiratory failure in bilateral diaphragmatic paralysis.

Adult↗