Continuous versus bilevel positive airway pressure in a patient with idiopathic central sleep apnea

A 57-yr-old man with idiopathic central apnea is reported. He presented at our hospital complaining of excessive daytime sleepiness. Polysomnography, including esophageal pressure monitoring, confirmed central sleep apnea with an apnea index of 27/h. He had mild non-insulin-dependent diabetes mellitus (NIDDM) but no signs of diabetic neuropathy or other background diseases. The ventilatory responses to hypoxia and hypercapnia tested while he was awake indicated increased respiratory chemosensitivity. We applied nasal continuous positive airway pressure (CPAP) and bilevel positive airway pressure (BPAP) in an attempt to compare the possible difference in therapeutic efficacy. Although nasal CPAP completely reversed central apnea, nasal BPAP adversely affected both apnea length and frequency in an applied pressure-dependent manner. Arterial blood gas analyses while he was being treated indicted alveolar hypoventilation with CPAP and hyperventilation with BPAP. Additionally, administration of a mixed gas containing 5% CO2 through a face mask had a significant effect on the disappearance of central apnea in this patient. These findings support the theory that the arterial PCO2 level is critical in generating idiopathic central apnea and that nasal CPAP therapy may be effective in eliminating central apnea by raising the PaCO2.     

Randomised trial of elective continuous positive airway pressure (CPAP) compared with rescue CPAP after extubation

AIM: To determine if a weaning regimen on flow driver continuous positive airway pressure (CPAP) would decrease the number of ventilator days but increase the number of CPAP days when compared with a rescue regimen. METHODS: Fifty eight babies of 24-32 weeks gestation with respiratory distress syndrome (RDS) were studied prospectively. After extubation they were randomly allocated to receive CPAP for 72 hours (n = 29) according to a weaning regimen, or were placed in headbox oxygen and received CPAP only if present "start CPAP" criteria were met (n = 29, rescue group). RESULTS: There was no difference in successful extubation at 72 hours, 1 and 2 weeks, between the groups in terms of the number of reventilation episodes, reventilation days, or in total days of CPAP. Birthweight, gestational age, race, day of first extubation, antenatal or postnatal steroids, patent ductus arteriosus status and maximal mean airway pressure used were of no value in predicting success or failure at 72 hours, 1, or 2 weeks. CONCLUSION: The weaning regimen did not decrease the number of ventilator days or days on CPAP compared with the rescue regimen. The rescue regimen on flow driver CPAP seems to be a safe and effective method of managing a baby of 24-32 weeks gestation who has been ventilated for RDS or immature lung disease.     

Changes in urinary uric acid excretion in obstructive sleep apnea before and after therapy with nasal continuous positive airway pressure

STUDY OBJECTIVE: To assess the utility of urinary uric acid excretion as a marker of nocturnal hypoxia in patients with obstructive sleep apnea-hypopnea syndrome (OSAHS) before and after the institution of nasal continuous positive airway pressure (CPAP). DESIGN: Prospective, open. SETTING: Sleep Disorders Laboratory, Veterans Affairs Medical Center. PARTICIPANTS: Thirty consecutive male subjects, 20 with OSAHS and 10 without OSAHS. MEASUREMENTS AND METHODS: Spot morning urine and venous blood samples were obtained in all subjects; samples were also obtained after the application of CPAP in those with OSAHS. Uric acid excretion, normalized to creatinine clearance, was calculated as the product of urinary uric acid and serum creatinine concentrations divided by urine creatinine concentration. In patients with OSAHS, uric acid excretion was 0.55+/-0.1 mg/dL before CPAP therapy and decreased to 0.30+/-0.01 mg/dL after CPAP therapy (p < 0.001). The latter value did not differ significantly from the mean value (0.32+/-0.03 mg/dL) in the control group. Uric acid excretion in OSAHS patients correlated significantly with the apnea-hypopnea index (r=0.42; p<0.0003). CONCLUSION: Uric acid excretion is increased in OSAHS patients and normalizes after CPAP treatment, most likely reflecting differences in tissue oxygenation between the two conditions. Further studies in large number of patients may confirm the usefulness of this simple test for diagnosis and follow-up of patients with OSAHS.     

Chymase gene locus is not associated with myocardial infarction and is not linked to heart size or blood pressure

The chymase gene is said to be important for the generation of angiotensin II in the heart and therefore is a candidate gene for heart disease. However, we were unable to find an association between allelic variants of the chymase gene and acute myocardial infarction or linkage between the chymase gene locus and heart size.     

Effects of nasal continuous positive airway pressure therapy on respiratory parameters of upper airway patency in patients with obstructive sleep apnea syndrome

OBJECTIVES: To assess whether an initial treatment with nasal continuous positive airway pressure (NCPAP) therapy, applied for one night, had any effect on airway patency. METHODS: In 18 patients with obstructive sleep apnea syndrome (OSAS), we measured the total resistance of the respiratory system (Rrs) and their relevant lung functions before and after polysomnography, with and without NCPAP therapy. The Rrs was measured at 3 Hz with the forced oscillation technique. The overnight changes in the specific respiratory conductance (SGrs=reciprocal of the Rrs per unit lung volume) was also calculated in the sitting position. Since many reports have suggested that obesity, through fat deposits around the pharynx, can affect the mechanical and neuromuscular properties of the upper airway, we also investigated if the degree of obesity was related to the magnitude of improvement in these parameters. RESULTS: After the first night of NCPAP therapy, the Rrs decreased (sitting: 4.8+/-0.4 vs 4.3+/-0.4 cm H20/L/s, p < 0.05; lying: 6.5+/-0.4 vs 5.6+/-0.4 cm H20/L/s, p < 0.05) and the maximal voluntary ventilation increased in the morning (sitting: 101.6+/-5.8% vs 106.4+/-4.5%, p < 0.05; lying: 91.2+/-5.4% vs 97.9+/-4.7%, p < 0.05). The overnight difference in the SGrs showed a significant improvement after the initial treatment with NCPAP therapy (p < 0.05). However, the lung volume, flow volume loop, and closing volume in the morning did not change significantly after the therapy. An overnight decrease in the Rrs following NCPAP therapy is significantly correlated with the body mass index (sitting: r=0.54, p < 0.05; lying: r=0.61, p < 0.01). CONCLUSION: The improvements in Rrs without changes in spirometry may reflect improved upper airway patency after NCPAP therapy. The degree of obesity is suggested to be associated with the treatment effect on upper airway in patients with OSAS.     

Cerebral hemodynamic changes in sleep apnea syndrome and effect of continuous positive airway pressure treatment

BACKGROUND AND OBJECTIVE: A clear association among snoring, sleep apnea, and increased risk of stroke has been shown by previous studies. However, the possible role played by sleep apnea in the pathogenesis of cerebrovascular disease is subject to debate. To evaluate the influence of hemodynamic changes caused by obstructive sleep apnea syndrome (OSAS), we investigated cerebrovascular reactivity to hypercapnia in patients with OSAS. METHODS: The study was performed at baseline and after 1 night and 1 month of nasal continuous positive airway pressure (n-CPAP) therapy, with patients in the waking state (8:00 to 8:30 AM and 5:30 to 6:00 PM) with transcranial Doppler ultrasonography. Cerebrovascular reactivity was calculated with the breath-holding index (BHI). RESULTS: In the baseline condition, compared with normal subjects, patients with OSAS showed significantly lower BHI values in both the morning (0.57 versus 1.40, p < 0.0001) and the afternoon (1.0 versus 1.51, p < 0.0001). Cerebrovascular reactivity was significantly higher in the afternoon than it was in the morning in both patients (p < 0.0001) and controls (p < 0.05). In patients, the BHI returned to normal values, comparable with those of control subjects, after both 1 night and 1 month of n-CPAP therapy. CONCLUSIONS: These findings suggest an association between OSAS and diminished cerebral vasodilator reserve. This condition may be related to the increased susceptibility to cerebral ischemia in patients with OSAS, particularly evident in the early morning.     

Acute effects of nasal continuous positive airway pressure on 24-hour blood pressure and catecholamines in patients with obstructive sleep apnea

OBJECTIVE: To estimate the risk for spina bifida associated with the common mutation C677T of the MTHFR gene in a country with a relatively low prevalence of NTDs. DESIGN: Case-control study. SUBJECTS: Cases: 203 living patients affected with spina bifida (173 myelomeningocele and 30 lipomeningocele); controls: 583 subjects (306 young adults and 277 unselected newborns) from northern and central-southern Italy. SETTING: Cases: three spina bifida centres; young adult controls: DNA banks; newborn controls: regional neonatal screening centres. MAIN OUTCOME MEASURES: Prevalence of the C677T genotypes in cases and controls by place of birth; odds ratios for spina bifida and estimated attributable fraction. RESULTS: The prevalence of T/T, T/C, and C/C genotype was 16.6%, 53.7%, and 29.7% in controls and 25.6%, 43.8%, and 30.6% in cases, respectively. We found no differences between type of defect or place of birth. The odds ratio for spina bifida associated with the T/T genotype v C/C plus T/C was 1.73 (95% CI 1.15, 2.59) and the corresponding attributable fraction was 10.8%. No increased risk was found for heterozygous patients (OR=0.79, 95% CI 0.53-1.18). CONCLUSION: This study, as well as the meta-analysis we updated, shows that homozygosity for the MTHFR C677T mutation is a moderate risk factor in Europe, and even in Italy where there is a relatively low prevalence of spina bifida. The estimated attributable fraction associated with this risk factor explains only a small proportion of cases preventable by periconceptional folic acid supplementation. Thus, other genes involved in folate-homocysteine metabolism, their interaction, and the interaction between genetic and environmental factors should be investigated further.     

The use of the BiPAP biphasic positive airway pressure system in acute spinal cord injury

Transurethral electrovaporization of the prostate (TVP) is a new minimally invasive procedure for treatment of enlargement of prostate. Between April 1996 and September 1997, TVP was carried out in 109 cases with symptoms of lower urinary tract obstruction. A Stortz spike electrode and a Stortz vapor cutting electrode were used for vaporization electrodes. Efficacy parameters evaluated included International Prostate Symptom Score, peak uroflow and postvoid residual volume. By September 1997, 32 cases (spike electrode) and 33 cases (vapor cutting electrode) could be followed up and evaluated. They have shown both subjective and objective voiding improvement. The improvements in subjective symptom scores and objective voiding parameters were not significantly different between the two electrode groups. Early complications included urinary retention, intraoperative burn, stress incontinence, blood transfusion and postoperative hemorrhage. Late complications included urethral stricture, bladder neck contracture and bladder stone. TVP was found to have several advantages, particularly minimal bleeding and the low incidence of postoperative morbidity. The technique is simple and symptoms improve at an early stage following surgery. This study demonstrates that TVP is a safe and effective modality for treatment of BPH. However, long-term studies with larger numbers of patients are needed.     

Sleep and neuromuscular disease: bilevel positive airway pressure by nasal mask as a treatment for sleep disordered breathing in patients with neuromuscular disease

The Fas receptor (APO-1/CD95) is capable of inducing apoptosis of lymphoid cells and is expressed in some non-Hodgkin's lymphomas (NHLs). Fas expression is up-regulated at the surface of normal B cells upon triggering of the CD40 receptor. In this report, we investigated the sensitivity of NHLs to Fas-mediated apoptosis induced by anti-Fas monoclonal antibodies (MAbs) and its possible modulation by CD40 ligation in 18 NHL biopsy samples of various histological subtypes. Flow cytometric analysis showed that the fraction of Fas-expressing lymphoma cells was highly variable from sample to sample (from 1% to 93%, mean value 46%). The frequency of apoptotic cells was not significantly increased upon treatment with an anti-Fas MAb compared with control MAb in the 18 NHL cases analysed. The sensitivity of lymphoma cells to Fas-mediated apoptosis was correlated neither with the histological subtypes nor with the level of Fas expression. Activation of neoplastic B cells by CD40 ligation resulted in significant increases in Fas expression and Fas-induced apoptosis among the five B-NHL cases tested. The overall increase in apoptotic rates was moderate and remained lower in tumour samples than in control CD40-activated normal tonsil B cells. Altogether, our results indicate that the sensitivity to Fas-induced apoptosis is null or weak in NHL cells, irrespective of their histological subtype, and that it can be increased to a moderate and variable degree by CD40 ligation on neoplastic B cells. This may be an impediment to the development of Fas-based therapies for NHLs.     

Reversal of sinus arrest and atrioventricular conduction block in patients with sleep apnea during nasal continuous positive airway pressure

Sinus arrest and atrioventricular (AV) block have been demonstrated in as much as 30% of patients with sleep apnea (SA). The reversal of heart block after tracheostomy has been shown. Nasal continuous positive airway pressure (nCPAP) now is widely used as the treatment of SA, but little data are available on the effect of nCPAP on heart block in patients with SA. During a 17-mo period 239 patients were found to have SA in an ambulatory study. Heart block was identified in 17 (16 male, one female) of these patients. Standard polysomnography and two-channel long-term ECG before and during nCPAP therapy were performed in order to assess the effect of nCPAP on SA and heart block. Mean age of the 17 patients was 50.7 yr (range, 27 to 78 yr), mean respiratory disturbance index (RDI) was 90/h (SD +/- 36.1) before nCPAP and 6/h (SD +/- 6.2) on the second treatment night. The number of episodes of heart block during sleep decreased significantly (p < 0.001) from 1,575 before therapy to 165 during nCPAP. In 12 patients (70.6%) heart block was totally prevented by nCPAP. In another three patients, there was a 71 to 97% reduction in the number of episodes of heart block on the second treatment night, and in two of them a complete reversal occurred thereafter. Two patients exhibited an increase in block frequency during nCPAP, which was reversed after 4 wk of nCPAP in one but persisted in the other.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of continuous positive airway pressure on obstructive sleep apnea and left ventricular afterload in patients with heart failure

BACKGROUND: The objectives of this study were to determine the effects of continuous positive airway pressure (CPAP) on blood pressure (BP) and systolic left ventricular transmural pressure (LVPtm) during sleep in congestive heart failure (CHF) patients with obstructive sleep apnea (OSA). In CHF patients with OSA, chronic nightly CPAP treatment abolishes OSA and improves left ventricular (LV) ejection fraction. We hypothesized that one mechanism whereby CPAP improves cardiac function in CHF patients with OSA is by lowering LV afterload during sleep. METHODS AND RESULTS: Eight pharmacologically treated CHF patients with OSA were studied during overnight polysomnography. BP and esophageal pressure (Pes) (ie, intrathoracic pressure) were recorded before the onset of sleep and during stage 2 non-rapid eye movement sleep before, during, and after CPAP application. OSA was associated with an increase in systolic BP (from 120.4+/-7.8 to 131.8+/-10.6 mm Hg, P<0.05) and systolic LVPtm (from 124.4+/-7.7 to 137.2+/-10.8 mm Hg, P<0.05) from wakefulness to stage 2 sleep. CPAP alleviated OSA, improved oxyhemoglobin saturation, and reduced systolic BP in stage 2 sleep to 115.4+/-8.5 mm Hg (P<0.01), systolic LVPtm to 117.4+/-8.5 mm Hg (P<0.01), heart rate, Pes amplitude, and respiratory rate. CONCLUSIONS: In CHF patients with OSA, LV afterload increases from wakefulness to stage 2 sleep. By alleviating OSA, CPAP reduces LV afterload and heart rate, unloads inspiratory muscles, and improves arterial oxygenation during stage 2 sleep. CPAP is a nonpharmacological means of further reducing afterload and heart rate during sleep in pharmacologically treated CHF patients with OSA.     

Long-term evolution of daytime somnolence in patients with sleep apnea/hypopnea syndrome treated by continuous positive airway pressure

We demonstrated in a previous study that excessive daytime sleepiness (EDS) in patients who have sleep apnea/hypopnea syndrome (SAHS) and are undergoing continuous positive airway pressure (CPAP) treatment improved differently in two groups of patients: in group I, multiple sleep latency tests (MSLT) were normalized after 50 days of treatment (individual value > 10 minutes), whereas they remained low (individual value < 10 minutes) in group II, with a significant difference between groups. To evaluate the long-term evolution of daytime somnolence under nasal CPAP treatment, five patients from group I and seven patients from group II underwent a new polysomnography and MSLT 4 years after the previous study. Clinical, polysomnographic and MSLT results obtained at baseline before treatment (T1), after the initial 50-day period of CPAP treatment (T2), and after 4 years (T3) were compared. The significant difference in mean MSLT value between the two groups previously observed at T1 and T2 disappeared at T3 (group I: 12.4+/-5.9 minutes; group II: 9.7+/-5.9 minutes). We found that this long-term improvement in excessive daytime somnolence was independent of the initial MSLT value, the severity of SAHS, and the initial MSLT changes under nasal CPAP. Long-term MSLT evolution was significantly correlated to CPAP compliance. These results demonstrate that even in the absence of a significant increase in MSLT at the beginning of CPAP treatment, further improvement is still possible several years later, which may encourage the regular, long-term use of nasal CPAP by patients.     

Evaluation of continuous measurement of cardiac output with thermodilution in critical patients

Pregnant women with inflammatory bowel disease and their physicians should be aware of factors that may affect the outcome of the pregnancy. Proper patient education, along with a physician team approach, usually ensure completion of an uneventful pregnancy.     

Sleep apnea syndrome in patients with diabetes. Effectiveness of treatment for respiratory assistance at night with continuous positive airway pressure

The group of 30 patients with OSA and diabetes type I or II has been examined. After the first test with MESAM 4, 5 patients with considerable nocturnal desaturation and heart rate disorders during sleep have been found. All diabetes type II. Two polisomnographic studies (the first diagnostic polisomnography and the second study for the settlement of treatment with CPAP) have been performed in the patients. After 6 months of applying CPAP all the patients have been examined again. The apnoea index was decreased (from 87.5 to 11.2) and a better control of both systemic arterial pressure and glycaemia, saturation > 80% has been obtained.     

Effects of nasal continuous positive airway pressure on breathing pattern and respiratory drive in patients with obstructive sleep apnea syndrome

To examine the influence of continuous positive airway pressure (CPAP) therapy on respiratory center drive in patients with obstructive sleep apnea syndrome (OSAS), 20 normocapnic OSAS patients (group 0) and 20 simple snoring patients were studied. In the first night, diagnostic polysomnography (PSG) was performed. Before and after PSG monitoring, mouth occlusion pressure (P0.1), tidal volume (VT), minute ventilation (VE), respiratory rate (RR), inspiratory time (Ti), expiratory time (Te), total cycle duration (Ttot), inspiratory duty cycle (Ti/Ttot), mean inspiratory flow (VT/Ti) and effective inspiratory impedance (P0.1/VT/Ti, Ieff) were measured while they were breathing room air. In the following night the OSAS patients were treated with nasal CPAP and PSG monitoring and the above mentioned measurements were repeated. The results showed that pre-PSG values of P0.1, RR and P0.1/VT/Ti in the OSAS patients were significantly higher than those in the snoring patients, while VT, Ti, Te and Ttot values were lower. In the first night, the post-PSG P0.1 value in the OSAS patients increased markedly as compared with the pre-PSG. After overnight nasal CPAP therapy, the respiratory disorder index in the OSAS patients decreased markedly, the nadir SaO2 increased markedly, but the post-PSG P0.1 value did not increase significantly. It is concluded that, before sleep, OSAS patients exhibit a higher respiratory drive and a shallow and frequent breathing pattern as compared with simple snoring patients. After nocturnal sleep, the respiratory drive of OSAS patients increases significantly, the breathing pattern becomes more shallow and frequent. Nasal CPAP may effectively relieve the sleep apnea and hypopnea as well as the resulting hypoxemia and therefore correct the changes in breathing pattern and respiratory drive through nocturnal sleep in patients with OSAS.     

Nasal-continuous positive airway pressure in the treatment of near-drowning in freshwater

In patients who have experienced near-drowning, hypoxemia is the major clinical consequence. We report two cases of patients who have experienced near-drowning in freshwater who were successfully treated with nasal-continuous positive airway pressure (N-CPAP) plus oxygen therapy. Both patients presented a radiographic appearance of bilateral pulmonary edema. We suggest the use of N-CPAP as an easier and less costly alternative to tracheal intubation for treating near-drowning in patients who are breathing spontaneously and who have not experienced loss of consciousness.     

A genetic propensity to high factor VII is not associated with the risk of myocardial infarction in men

Interictal brain SPECT is useful for the localization of a seizure focus. Concomitant hypoperfusion of the ipsilateral thalamus on interictal SPECT has been noted for temporal lobe epilepsy. In this study, we aimed to evaluate the prevalence of thalamic hypoperfusion ipsilateral to temporal hypoperfusion (ipsilateral thalamic hypoperfusion) and to assess the usefulness of this finding for the lateralization of epileptic foci on interictal SPECT for temporal lobe epilepsy patients. METHODS: Forty-six patients with refractory temporal lobe epilepsy underwent interictal brain SPECT after intravenous injection of 555-740 MBq of 99mTc-ECD. Perfusion impairments in the brain, especially the temporal lobe and thalamus, were evaluated. The localization of seizure foci was determined in conjunction with scalp, ictal and cortical electroencephalography, MRI and clinical outcomes. Ictal SPECT was performed for 5 of the 12 patients. RESULTS: Concomitant decreased perfusion in both the temporal lobe and the ipsilateral thalamus was observed for 12 (26%) of 46 temporal lobe epilepsy patients on interictal brain SPECT. Seven patients showed hypoperfusion in the left temporal lobe and ipsilateral thalamus. Five patients showed hypoperfusion in the right temporal lobe and ipsilateral thalamus. In addition, hypoperfusion in the ipsilateral basal ganglia (ten patients) or contralateral cerebellum (four patients) was observed. CONCLUSION: Ipsilateral thalamic hypoperfusion is not uncommon in temporal lobe epilepsy. The exact mechanism causing ipsilateral thalamic hypoperfusion is uncertain; however, corticothalamic diaschisis may be an important factor. This finding may aid in the lateralization of seizure foci on interictal brain SPECT.