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Biomedical subjects

D O Rodenstein

Publications and source records attributed to D O Rodenstein.

At least 55 records · Page 3Linked to original sources
PubMed1996

Glottic aperture and effective minute ventilation during nasal two-level positive pressure ventilation in spontaneous mode.

Our goal was to verify glottic behavior and its effects on effective minute ventilation during intermittent positive pressure ventilation applied at increasing inspiratory pressure levels through a nasal mask (nIPPV) using a two-level positive pressure ventilator (two-level IPPV) in spontaneous mode. Ten subjects were studied while awake. The spontaneous mode was used at three levels of inspiratory positive airway pressure (IPAP): 10, 15, and 20 cm H2O. The expiratory pressure was kept at 4 cm H2O. Records of spontaneous breathing without nIPPV were also performed. The glottis was continuously monitored through a fiberoptic bronchoscope. We measured, breath by breath, the widest inspiratory angle formed by the vocal cords at the anterior commissure, the corresponding tidal volume (with respiratory inductive plethysmography), the respiratory frequency and other indices. Our data during wakefulness show that inspiratory pressures of 10 and 15 cm H2O did not result in increases in effective minute ventilation with respect to spontaneous breathing. Only at 20 cm H2O of IPAP did effective minute ventilation increase. This was due essentially to a decrease in respiratory frequency with increasing pressures, offsetting increases in tidal volume at 10 and 15, but not at 20 cm H2O of inspiratory pressure. Changes in end-tidal CO2 suggest that alveolar ventilation increased due to the change in breathing pattern. Contrary to what we observed previously with either two-level IPPV used in the controlled mode, or nIPPV performed with volumetric ventilators, the glottis did not play any noticeable role in the control of effective minute ventilation.

Adult↗
PubMed1996

Acceptance and long-term compliance with nCPAP in patients with obstructive sleep apnoea syndrome.

Previous studies have generally shown poor effective long-term compliance with nasal continuous positive airway pressure (nCPAP) in patients with obstructive sleep apnoea syndrome (OSAS). We performed a retrospective study of patients treated with nCPAP for more than one year. Compliance was defined as the average number of hours of nCPAP use per day, where hours of use were obtained from the built-in time counter of the nCPAP device, after deduction of the 10% difference between effective use and time counters previously shown by others. We present data on the first 95 patients for whom results were available. The follow-up period was 784 +/- 366 (mean +/- SD) days for the whole group. Compliance was 5 +/- 1.8 h. For a subgroup of 36 patients, we had data on two consecutive follow-up periods (673 +/- 235 and 390 +/- 147 days for the first and second period, respectively). Compliance remained stable (5.2 +/- 1.5 and 5 +/- 2.3 h, respectively). For the whole group, a significant correlation was found between compliance and sleep fragmentation expressed as the movement arousal index (r = 0.226). During a similar 3 year period, 155 patients with a confirmed diagnosis of OSAS were offered a nCPAP trial. CPAP was actually delivered for home use to 117 patients (76%). During this same 3 year period, only 21 patients out of a total of 192 followed-up in our institution quit treatment, mainly due to intolerance or cure. These results indicate that in a nonselected group of obstructive sleep apnoea syndrome patients a high and stable compliance with nasal continuous positive pressure can be achieved, contradicting recent results of other series.

Adult↗
PubMed1996

The single-breath diffusing capacity for carbon monoxide in obstructive sleep apnea and obesity.

BACKGROUND: We have observed high values of single-breath diffusing capacity for carbon monoxide (Dco) in patients with obstructive sleep apnea (OSA). STUDY OBJECTIVES: To confirm this observation and to determine the factors influencing diffusion indices in patients with OSA. As weight excess was found to be the major determinant of increased diffusion indices, the adequacy of various prediction equations was evaluate in obese subjects. DESIGN: Retrospective data collection. SETTING: University hospital. METHODS: DCO was measured in patients with OSA and in nonapneic subjects who served as control SUBJECTS: The results were expressed with respect to our own reference values and also to other prediction equations. RESULTS: In moderate/severe OSA (apnea/hypopnea index [AHI] > or = 30), both DCO and transfer coefficient (KCO) were increased and KCO was positively correlated with AHI and body mass index (BMI). Diffusion indices were not different between patients with moderate/severe OSA and nonapneic control subjects matched for age and BMI. In the latter group, KCO was also correlated with BMI. In our obese patients (BMI, 36.7 +/- 5.6 kg/m2), DCO was about 10% and KCO was 20 to 25% greater than predicted by standard reference equations. CONCLUSIONS: DCO and KCO are increased in a typical population of patients with moderate/severe OSA. This appears to be due to weight excess and not to OSA itself. In obese subjects, whether apneic or not, BMI is a determinant of diffusion indices that are higher than predicted by equations relying on age and stature alone.

Adult↗
PubMed1995

Effects of nasal positive-pressure hyperventilation on the glottis in normal awake subjects.

We have recently observed obstructive apneas during nasal intermittent positive-pressure ventilation (nIPPV) and suggested that they were due to hypocapnia-induced glottic closure. To confirm this hypothesis, we studied seven healthy subjects and submitted them to nIPPV while their glottis was continuously monitored through a fiber-optic bronchoscope. During wakefulness, we measured breath by breath the widest inspiratory angle formed by the vocal cords at the anterior commissure along with several other indexes. Mechanical ventilation was progressively increased up to 30 l/min. In the absence of diaphragmatic activity, increases in delivered minute ventilation resulted in progressive narrowing of the vocal cords, with an increase in inspiratory resistance and a progressive reduction in the percentage of the delivered tidal volume effectively reaching the lungs. Adding CO2 to the inspired gas led to partial widening of the glottis in two of three subjects. Moreover, activation of the diaphragmatic muscle was always associated with a significant inspiratory abduction of the vocal cords. Sporadically, complete adduction of the vocal cords was directly responsible for obstructive laryngeal apneas and cyclic changes in the glottic aperture resulted in waxing and waning of tidal volume. We conclude that in awake humans passive ventilation with nIPPV results in vocal cord adduction that depends partly on hypocapnia, but our results suggest that other factors may also influence glottic width.

Adult↗
PubMed1995

Effects of nasal positive-pressure hyperventilation on the glottis in normal sleeping subjects.

We have previously observed that, in normal awake subjects passively hyperventilated with intermittent positive-pressure ventilation delivered through nasal access (nIPPV), the glottis could interfere with the ventilation. We report on data obtained in the same subjects during stable sleep. In all cases, the glottis was continuously observed through a fiber-optic bronchoscope, and other indexes were also continuously recorded. Mechanical ventilation was progressively increased up to 30 l/min. We have observed during passive nIPPV in stable sleep that increases in delivered minute ventilation (VEd) resulted in progressive narrowing of the glottic aperture, with increases in inspiratory resistance and progressive reductions in the percentage of the delivered tidal volume effectively reaching the lungs. For a given level of VEd, comparisons showed that the glottis was significantly narrower during sleep than during wakefulness and that the glottis was significantly narrower during stage 2 than during stages 3/4 non-rapid-eye-movement sleep. Moreover, when CO2 is added to the inspired air, glottic aperture increased in five of nine trials without changes in sleep stage. We also observed a significant negative correlation between glottic width and the VED, independent of the CO2 level. We conclude that during nIPPV glottis narrowing results in a decrease in the proportion of the delivered tidal volume reaching the lungs.

Adult↗
PubMed1995

Normal pregnancy in primary alveolar hypoventilation treated with nocturnal nasal intermittent positive pressure ventilation.

Nocturnal nasal intermittent positive pressure ventilation (NIPPV) is increasingly used to treat chronic respiratory failure in a wide variety of conditions (myopathies, Ondine's curse, kyphoscoliosis, etc.) and allows a normal everyday life. Some of these diseases affect women of childbearing age. We report on a young woman suffering from primary alveolar hypoventilation, who presented with limitation of daytime activities, severe oxygen desaturation during sleep, polycythaemia and pulmonary hypertension. These abnormalities completely reversed after a few months of NIPPV applied through a nasal mask. Whilst under ventilatory assistance during sleep, she had an uneventful pregnancy and delivery of a normal baby. We suggest that in selected patients requiring NIPPV, pregnancy can be contemplated with a reasonable level of safety both for the mother and the child, provided that adequate mechanical ventilatory assistance during sleep is maintained throughout pregnancy.

Adult↗
PubMed1995

Management of sleep apnoea syndrome.

Obstructive sleep apnoea is a chronic condition characterized by repetitive episodes of upper airway collapse during sleep, leading to sleep fragmentation. The management of sleep apnoea consists of general and specific measures. General measures should include weight loss in overweight patients; avoidance of alcohol during the evening hours; avoidance of any hypnotic drug. Specific measures may range from simple position training in patients with positional sleep apnoea (sleep apnoea appearing only when lying on the back) of slight severity; to oral appliances with the aim of creating a prognathism during sleep, to the introduction of a nasopharyngeal tube during sleep every night. When position training, oral appliances or a nasopharyngeal tube are used, their effect should be monitored by full night polysomnography. The best specific treatment for sleep apnoea is nasal continuous positive airway pressure. The main problem with nasal continuous positive airway pressure is the long-term compliance which should be assessed regularly over the years. In cases where nasal continuous positive airway pressure is not tolerated or compliance is bad, a surgical treatment can be proposed. Uvulopalatopharyngoplasty seems to give disappointing results. By contrast, maxillomandibular surgery is credited with the best results available as far as surgery is concerned, comparable to nasal continuous positive airway pressure.

Alcohol Drinking↗
PubMed1995

Nasal continuous positive airway pressure in the perioperative management of patients with obstructive sleep apnea submitted to surgery.

Anesthetic, sedative, and analgesic drugs have been shown in animals and humans to selectively impair upper airway muscle activity. In patients with an already compromised upper airway, these drugs may further jeopardize upper airway patency, especially during sleep. Thus, patients with obstructive sleep apnea syndrome (OSAS) are at high risk for surgery because of the use of the aforementioned drugs in the perioperative period. It has been recommended that such drugs should be avoided or used with extreme caution in patients with OSAS submitted to surgery. We report herein on 16 adult patients with documented OSAS undergoing various types of surgical procedures, including coronary artery bypass surgery. Anesthesia was carried on with the usual type of drugs for each type of surgery. Postoperative opioid analgesia and sedation were not restricted. The first patient, whose OSAS was diagnosed but not treated, died after various complications, including a respiratory arrest in the ward. The second patient experienced serious postoperative complications until a treatment for OSAS with nasal continuous positive airway pressure (N-CPAP) was instituted, and thereafter he made an uneventful recovery. The 14 following patients were started on N-CPAP before surgery, were put on N-CPAP as soon as extubated, on a near-continuous basis, for 24 to 48 h and thereafter for all sleep periods. None of them had major complications. The intensive care unit and hospital stays were the normal ones for each type of surgery in our institution. We conclude that N-CPAP started before surgery and resumed immediately after extubation allowed us to safely manage a variety of surgical procedures in patients with OSAS, and to freely use sedative, analgesic, and anesthetic drugs without major complications. Every effort should be made to identify patients with OSAS and institute N-CPAP therapy before surgery.

Adult↗
PubMed1993

Maximum respiratory pressures in trumpet players.

We studied whether experienced trumpet players can develop higher pressures with their inspiratory and expiratory muscles than untrained subjects. Twelve male trumpet players (mean age, 22.4 +/- 3.3 years) participated in the study. All of them had played the trumpet for at least 4 years and were nonsmokers. Twelve healthy male subjects (mean age, 23.3 +/- 3.1 years) participated as a control group. There were no differences in spirometric parameters between both groups. Maximum respiratory pressures were higher in the trumpet player group (trumpet players: Pmax 151.3 +/- 19.8 cm H2O; Pemax, 234.6 +/- 53.9 cm H2O; control group: Pemax, 106.7 +/- 10.4 cm H2O; Pemax, 189.6 +/- 14.6 cm H2O). We concluded that in young trumpet players, maximum respiratory pressures are higher than in young people who do not play wind instruments. This is most probably a consequence of respiratory muscle training with a wind instrument.

Adult↗
PubMed1993

Management of simple snoring in adults.

The management of simple snoring in adults is reviewed. Snoring is associated with oscillations of the soft palate and adjacent structures, as a consequence of a critically reduced pharyngeal cross-sectional area under conditions of sleep-induced flow limitation. Anatomical and physiological factors resulting in upper airway collapse and snoring are reviewed. The conservative treatment of snoring encompasses weight loss, alcohol and sedatives avoidance, as well as smoking cessation. Nasal obstruction should be relieved, either medically or surgically. If these measures fail, polysomnography should be performed. Patients with obstructive sleep apnoea should be offered nasal continuous positive airway pressure therapy. Uvulopalatopharyngoplasty can be proposed to nonapnoeic snorers, with a good chance of success, as far as reported snoring is concerned. Unfortunately, this has not been confirmed by objective recordings, and long-term results have not been adequately studied.

Humans↗
PubMed1992

Assessment of uvulopalatopharyngoplasty for the treatment of sleep apnea syndrome.

Uvulopalatopharyngoplasty (UPPP) consists in the surgical removal of the uvula, part of the muscular portion of the soft palate and redundant palatal and pillar mucosa, and the tonsils. Since 1981, UPPP has been proposed for the treatment of sleep apnea syndrome. Polysomnographic studies have shown that in about half of the patients submitted to UPPP there is a 50% or greater reduction in apnea index. Attempts to identify presurgically those patients more likely to benefit from UPPP have yielded inconsistent results. Limited retrospective follow-up data suggest that UPPP does not modify the increased mortality associated with moderate and severe sleep apnea syndrome. Patients submitted to UPPP report subjective improvement, irrespective of the objective polysomnographic postsurgical results. It is suggested that polysomnographic evaluation of UPPP results should be mandatory; that any patient with 20 or more apnea/hypopneas per hour of sleep or sleep fragmentation after UPPP should be considered a treatment failure and be offered alternative therapy; and that UPPP should be performed only as part of prospective clinical trials including long-term follow-up.

Cause of Death↗
PubMed1992

Treatment of relapse of small cell lung cancer in selected patients with the initial combination chemotherapy carboplatin, etoposide, and epirubicin.

BACKGROUND: Relapse of small cell lung cancer is not usually treated with further chemotherapy as results are considered to be disappointing. METHODS AND RESULTS: Six patients with relapse of small cell lung cancer after a complete initial response and remission of more than one year responded to repeat treatment with the initial chemotherapy comprising carboplatin, etoposide, and epirubicin. The second remission ranged from six months to more than 15 months. CONCLUSION: In patients with a relapse of small cell lung cancer after a complete initial response and prolonged remission retreatment with the initial combination chemotherapy cannot be dismissed and requires further study.

Aged↗
PubMed1992

Diurnal and nocturnal diuresis and natriuresis in obstructive sleep apnea. Effects of nasal continuous positive airway pressure therapy.

Excessive nocturnal diuresis and natriuresis have been reported in patients with sleep apnea. The mechanisms responsible for these alternations in nocturnal renal function have not been clearly identified. To gain further insight into this matter, we studied 12 patients (one woman) with a mean +/- SD age of 50 +/- 9 yr and body mass index of 36.9 +/- 8.6 kg/m2. Polysomnography showed in all a sleep apnea syndrome with an apnea-hyponea index (AHI) of 81.3 +/- 41.7. Treatment with nasal continuous positive airway pressure (nCPAP) resulted in an AHI of 19.4 +/- 13.7 and in normalization of sleep characteristics. Diurnal renal function was normal in all subjects. Although untreated, patients showed an abolition of the well-known decrease in diuresis and natriuresis during the night (diurnal and nocturnal diuresis 56.3 +/- 26.8 and 77.2 +/- 33.4 ml/h, respectively, p = NS; diurnal and nocturnal fractional urinary Na+ excretion 0.42 +/- 0.09 and 0.70 +/- 0.55 ml/100 ml glomerular filtration [GF], respectively, p = NS). Results of nocturnal studies under nCPAP therapy showed a significant decrease in diuresis and natriuresis (nocturnal diuresis before and under nCPAP, respectively: 90.4 +/- 27.3 and 70.6 +/- 25.1 ml/h, p less than 0.02; nocturnal fractional urinary sodium excretion before and under nCPAP, respectively: 0.76 +/- 0.53 and 0.44 +/- 0.37 ml/100 ml GF, p less than 0.03). Morning blood levels of renin, aldosterone, antidiuretic hormone, epinephrine, and atrial natriuretic factor showed no significant difference before and under nCPAP, whereas norepinephrine significantly decreased from 309.5 +/- 104.2 before to 230.4 +/- 88.4 pg/ml under nCPAP (p less than 0.02).(ABSTRACT TRUNCATED AT 250 WORDS)

Circadian Rhythm↗
PubMed1992

Upper airway anesthesia induces airflow limitation in awake humans.

Upper airway receptors are thought to contribute to upper airway stability by reducing collapsing forces. Their activity can be abolished by topical anesthesia. We have measured in 16 healthy volunteers (mean +/- SD age, 23.7 +/- 1.6 yr) specific airway conductance (SGaw), maximal inspiratory (MIFR) and expiratory (MEFR) flow rates before and 15, 35, and 45 min after extensive upper airway anesthesia (UAA) with 10% lidocaine. Average values of MIFR decreased (p less than 0.01) 15 min after UAA, but they returned to or near to control values at 45 min: MIF25 (4.8 versus 6.0 L/s); MIF50 (5.1 versus 6.2 L/s); MIF75 (4.4 versus 5.3 L/s). Transient decreases in flow (V) rates, reaching zero flow in some subjects, were observed in 13 subjects during forced inspiratory vital capacity (FIVC) maneuvers and in seven subjects during forced expiratory vital capacity (FEVC) maneuvers. MEFR at 25, 50, and 75% FVC, SGaw, and FVC did not change after anesthesia. Simultaneous measurements of supraglottic pressure, V, and lung volume in 12 of the 16 subjects showed that the site of flow limitation was localized at the level of the glottis in all except one subject in whom there was both a glottic and a supraglottic obstruction. We conclude that extensive upper airway anesthesia induced a profound but transitory upper airway obstruction during FIVC and FEVC maneuvers. These findings are compatible with the concept of reflex regulation of upper airway caliber.

Adult↗
PubMed1991

Upper airway obstruction during nasal intermittent positive-pressure hyperventilation in sleep.

Episodes of apnoea for up to 1 min were observed in association with hypocapnia caused by passive nasal intermittent positive-pressure mechanical hyperventilation in 3 of 4 patients during sleep. Apnoea seemed to be caused by complete upper airways obstruction; we suggest that this finding was caused by active glottic closure. Avoidance of excessive hypocapnia during positive-pressure ventilation might help to avoid central-nervous-system mediated apnoeic episodes.

Adult↗