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Biomedical subjects

O Marrone

Publications and source records attributed to O Marrone.

At least 37 records · Page 2Linked to original sources
PubMed1995

Pulmonary haemodynamics in obstructive sleep apnoea.

The time course of right ventricular output (RVO) and transmural pulmonary artery pressure (PAP) changes, detected beat-by-beat, were analysed in a sample of obstructive sleep apnoea (OSA) episodes recorded in six patients with OSA syndrome. RVO showed a trend to a decrease during apnoeas, due to a decrease in heart rate, and decreased further in the immediate post-apnoeic period, due to a decrease in right ventricular stroke volume [post-apnoeic RVO = 82.6 +/- 9.3 (SD) % of the value in the immediate pre-apnoeic period; P < 0.01]. Both systolic and diastolic transmural PAP showed a progressive increase throughout apnoeas (from 23.7 +/- 7.3 to 29 +/- 6.9 and from 9.1 +/- 4.4 to 14.3 +/- 3.3 mmHg, respectively, from early to late apnoeic period; P < 0.01), and similarly high values in the late apnoeic and in the immediate post-apnoeic period. Therefore, cardiac output and arterial pressure in the pulmonary circulation undergo simultaneous inverse changes in OSA, similar to what was previously shown in the systemic circulation. Although these data cannot define accurately the behaviour of pulmonary vascular resistance, they suggest that pulmonary vascular resistance could also undergo continuous oscillations in OSA, with recurring peaks detectable between apnoea termination and the immediate post-apnoeic period.

Journal Article↗
PubMed1995

Respiratory sinus arrhythmia during obstructive sleep apnoeas in humans.

Respiratory sinus arrhythmia (RSA) reflects parasympathetic modulation of heart rate (HR) during the respiratory cycle. Since the time-course of RSA during obstructive sleep apnoea (OSA) is not known, an analysis was made of ECG in samples of consecutive OSA recorded in 5 patients during NREM sleep while breathing room air (OSA-AIR, mean lowest SaO2 83.0 +/- 6.5%) or supplemental oxygen (OSA +/- O2, mean lowest SaO2 91.7 +/- 2.2%), respectively. For each breath, HR at the transition from expiration to inspiration (HRei), and HR at maximal inspiration (HRie) were calculated, and the inspiratory increase in HR estimated as the ratio: HRie/subsequent HRie. Similarly, the expiratory decrease in HR was estimated as: HRie/subsequent HRei. RSA was identified by an inspiratory increase in HR (HRei/HRie < 1), and an expiratory decrease in HR (HRie/HRei > 1). OSA-AIR and OSA + O2 did not differ for duration or oesophageal pressure nadir. During OSA-AIR, the inspiratory increase in HR became progressively more marked from the first occluded to the first open breath, whereas during OSA + O2 it remained stable throughout the apnoeic cycle. The expiratory decrease in HR remained constant during the apnoeic phase, but was blunted in the first open breaths irrespective of O2 administration. In summary, hypoxia appeared to affect inspiratory, but not expiratory HR. Instead, the expiratory slowing of HR transiently disappeared in the immediate post-apnoeic phase, suggesting a possible effect of arousal or pulmonary inflation. These data suggest that the parasympathetic system may contribute to cardiovascular regulation during OSA.

Journal Article↗
PubMed1995

[The surgical treatment of obstructive sleep apnea syndrome].

Studies concerning the anatomical abnormalities of upper airways in patients affected by Obstructive Sleep Apnea Syndrome (OSAS) allowed the corrective surgical treatments in this syndrome. To provide an improvement or a definitive recovery of OSAS, various surgical treatments, i.e. functional nasal surgery, palatal surgery [Partial resection of palate (RPP), Uvulopalatopharingoplasty (UPPP), Palatopharingoplasty (PPP), modified Palatopharingoplasty (modified PPP)], mandibular and base tongue surgery, have been performed in order to obtain an enlargement of upper airways. It has been reported that in RPP, UPPP, PPP and modified PPP partial or total uvula and soft palate resection is conduct; in our research we performed modified PPP. 44 OSAS patients, severe or moderately severe form (polisomnographic diagnosis), underwent surgical treatment: 5 patients underwent functional nasal surgery; 9 patients underwent modified PPP; 29 patients underwent nasal and palatal surgery; only 1 patient underwent base tongue surgery. 32 patients underwent polisomnographic records after surgery (two months later) and we evaluated Apnea Index (I.A.) and a SaO2 low (nadir) with statistic tests. The results have been positive. Therefore, we have now 7 normal, 2 mild form, 7 moderate form, 3 moderately severe form and 13 severe form OSAS patients. If, on the one hand, all these surgical treatments can be considered a good way of therapy, on the other, only tracheostomy represents today the unfailing surgical therapy.

Humans↗
PubMed1994

Time course of right ventricular stroke volume and output in obstructive sleep apneas.

Because the behavior of right ventricular stroke volume (RVSV) in the obstructive sleep apnea syndrome (OSAS) is undefined, we studied the time course of RVSV by right heart catheterization during sleep in five OSAS patients. In 55 obstructive apneas, heart rate (HR) and RVSV were calculated beat-by-beat. RVSV was estimated by integrating the area under the pulmonary arterial (PA) blood velocity signal obtained by a velocity sensor-/micromanometer-tipped catheter. Compared with preapnea, mean RVSV did not change significantly during apnea, but decreased by 15% during postapnea. Analysis of RVSV in the respiratory cycle showed that postapneic RVSV was mostly reduced at maximal inspiration, suggesting a role of increased lung volume in decreasing RVSV. As for HR, it decreased significantly during apnea in four out of five patients. In all patients, HR returned to preapneic values during postapnea. Therefore, right ventricular output decreased slightly in most patients during late apnea because of decreased HR, whereas it decreased in all patients during postapnea because of decreased RVSV. These results, together with the known finding that PA pressure increases towards the end of apneas and remains elevated in the immediate postapnea, suggest that the most relevant changes in the pulmonary circulation occur at the resumption of ventilation, not during the apneic phase.

Adult↗
PubMed1994

The cardiovascular effects of obstructive sleep apnoeas: analysis of pathogenic mechanisms.

Obstructive sleep apnoeas (OSA) exert immediate marked cardiovascular effects, and may favour the development of systemic and pulmonary hypertension in the long-term. As for the pathogenesis of the acute cardiovascular changes, the first studies high-lighted the role of OSA-induced hypoxia and mechanical changes. However, more recent work pointed to the role played by the arousal reaction terminating OSA, and to the activity of the autonomic nervous system during apnoea and inter-apnoeic phase. As for the pathogenesis of chronic cardiovascular changes, recent findings suggest that the link between OSA and systemic hypertension may be through an abnormal function of the carotid body and underline the importance of chronic intermittent hypoxia versus continuous hypoxia in the development of stable systemic hypertension. On the other hand, OSA do not appear to enhance strongly the development of stable pulmonary hypertension. In this review, we analyze OSA-induced cardiovascular changes with particular emphasis on to the interplay of the possible pathogenic mechanisms involved. Acute OSA-induced cardiovascular alterations during the apnoeic phase appear to result mainly from the mechanical effects of OSA, while during the interapnoeic phase they seem mostly determined by chemical factors (hypoxia, hypercapnia) and by the arousal reaction. In addition, the role of reflex changes elicited by resumption of ventilation should be reconsidered, since lung inflation seems to exert a positive effect on the cardiovascular changes occurring at the end of OSA. This would be in contrast with the inhibitory effects described as "lung inflation reflex", and deserves further study.

Blood Pressure↗
PubMed1994

Slow and fast changes in transmural pulmonary artery pressure in obstructive sleep apnoea.

Our purpose was to assess how pulmonary artery pressure changes in relation to hypoxia and oesophageal pressure during obstructive sleep apnoeas. Transmural systolic pulmonary artery pressure (Ppa,STM), oxyhaemoglobin saturation (SaO2) and oesophageal pressure were analysed in two samples of consecutive obstructive apnoeas in each of four patients. In the first samples (samples A; probably recorded during non-rapid eye movement (NREM) sleep), SaO2 swings were small and repetitive. In the second samples (samples B; probably recorded during rapid eye movement (REM) sleep), they were large and more variable. Oesophageal pressure oscillated similarly in the two groups of samples. In all cases, transmural systolic pulmonary artery pressure progressively increased throughout apnoeas, and subsequently decreased in the interapnoeic periods. However, both early and end-apnoeic transmural systolic pulmonary artery pressure, remained stable in samples A; whilst they progressively increased in samples B. Transmural systolic pulmonary artery pressure at the beginning of each apnoea was inversely correlated with SaO2 at the end of the preceding apnoea. These results suggest that transmural systolic pulmonary artery pressure is influenced by SaO2, but does not vary at the same speed as SaO2. In all cases, beat-by-beat analysis showed, as expected, that the lower the oesophageal pressure, the higher the transmural systolic pulmonary artery pressure however, at each oesophageal pressure level, transmural systolic pulmonary artery pressure was more variable and higher, in samples B. In conclusion, transmural systolic pulmonary artery pressure in obstructive apnoeas shows rapid changes, which reflect oesophageal pressure variations, and slower changes, which are likely to be caused by SaO2.

Blood Pressure↗
PubMed1993

Thyroarytenoid muscle activity in sleep apneas.

In normal subjects the thyroarytenoid muscle (TA), a vocal cord adductor, has phasic expiratory activity during wakefulness that disappears during non-rapid-eye-movement (NREM) sleep. Fiber-optic studies have reported absent or irregular vocal cord movements during obstructive apneas and vocal cord adduction during central apneas. This study was designed to investigate TA activity during NREM sleep in 14 subjects with sleep apnea by means of intramuscular wire electrodes. During central apneas, which were recorded in three subjects, continuous TA activity was observed. During obstructive apneas, which were recorded in all subjects, two different patterns of TA activity were observed: 1) absence of any activity until arousal and 2) phasic activity throughout the apnea. The first pattern was detected in six subjects, whereas both patterns were observed in the remaining eight subjects. No correlation was found between obstructive apnea characteristics and presence or absence of TA activity. In all subjects TA underwent a marked activation during arousal. While nasal continuous positive airway pressure was applied during NREM sleep TA activity was always absent. The persistence of TA activity during central apneas suggests that they may represent an extreme prolongation of neural expiratory discharge. We speculate that a variable interaction of different stimuli acting during obstructive apnea may activate TA, which, in turn, may contribute to glottic narrowing.

Adult↗
PubMed1993

Catecholamines and blood pressure in obstructive sleep apnea syndrome.

To evaluate the release of catecholamines and their relationship with systemic blood pressure (BP) in normotensive patients with obstructive sleep apnea syndrome (OSAS), diurnal and nocturnal urinary norepinephrine (NE) and epinephrine (E) excretion in 12 normal subjects and in 10 OSAS patients were compared; in addition, nocturnal NE and E excretion were measured in the patients while receiving short-term CPAP. Blood pressure was continuously monitored in the patients during both nights of urine collection. In normal subjects, both NE and E excretion decreased from day to night. In the patients without CPAP, only NE excretion decreased at night, and BP increased from wakefulness to sleep; both NE and E excretion were higher in patients than in normal subjects. With CPAP, which prevented apneas, only E excretion decreased with respect to the previous night, while BP no longer increased during sleep. The extent of nocturnal E decrease with CPAP was not correlated to BP variations. These results suggest that in normotensive OSAS subjects, sympathetic nervous system activity, based on NE excretion, is continuously increased and is not affected by short-term CPAP treatment. Conversely, adrenal activity, based on E excretion, is also increased, but it tends to be normalized by short-term CPAP. No clear relationship could be found between sympatho-adrenal behavior and BP during sleep.

Adult↗
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↗