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Biomedical subjects

P Levi-Valensi

Publications and source records attributed to P Levi-Valensi.

At least 19 recordsLinked to original sources
PubMed1992

Survival in COPD patients with a daytime PaO2 greater than 60 mm Hg with and without nocturnal oxyhemoglobin desaturation.

There have been few studies examining the relationship between NOD and mortality in patients with COPD and none examining this relationship in those patients with a daytime PaO2 greater than 60 mm Hg. Is NOD related to early death, and if so, should nocturnal supplemental oxygen be considered as therapy for altering survival? We examined survival in 169 COPD subjects. Two definitions were used to classify subjects as NOD and non-NOD, one considering episodic desaturation associated mainly with REM sleep (definition 1) and one considering greater than 30 percent of time in bed spent below an SaO2 of 90 percent (definition 2) to be significant. Survival corrected for age was significantly better in non-NOD subjects. However, when stratified for supplemental oxygen use, survival remained better only in subjects separated by definition 1. There was a trend toward increased survival in 35 oxygen-treated vs 38 non-oxygen-treated NOD subjects (definition 1), but this difference was not statistically significant.

Circadian Rhythm↗
PubMed1992

[Kidney function and chronic respiratory insufficiency: relation to the ventilatory method. A physiopathological hypothesis apropos of a case].

The authors report the case of a patient with chronic obstructive pulmonary disease (COPD) whose renal function depends on the ventilatory pattern. The data appeared in opposition with the standard physiopathological notions with an improvement of renal function during mechanical ventilatory assistance and a degradation while spontaneous breathing. The authors suggest an original hypothesis based upon the increase of oxygen cost of breathing (OCB) with a redistribution of the intravascular blood flow to the diaphragm.

Acute Kidney Injury↗
PubMed1992

Sleep-related oxygen desaturation and daytime pulmonary haemodynamics in COPD patients.

It has been hypothesized that in chronic obstructive pulmonary disease (COPD), sleep-related hypoxaemia could lead to pulmonary hypertension (PH) and cor pulmonale, even in patients with only mild daytime hypoxaemia. We investigated the relationships between sleep variables and daytime pulmonary haemodynamics in 40 COPD patients with daytime arterial oxygen tension (PaO2) between 60-70 mmHg (8-9.3 kPa). Patients were considered as desaturators if they spent at least 30% of the sleep recording time with a transcutaneous O2 saturation (StcO2) less than 90%. Daytime arterial blood gases and pulmonary volumes could not discriminate desaturators "D" (n = 18) from non-desaturators "ND" (n = 22), but awake baseline StcO2, measured just prior to the onset of sleep, was lower in group D. Pulmonary artery mean pressure was significantly higher in group D (19.1 +/- 4.7 vs 16.8 +/- 1.9 mmHg, p less than 0.05) and all patients with PH (6 out of 40) belonged to group D. PH was observed in 6 of the 15 patients whose mean nocturnal StcO2 was less than 90% but in none of the 25 with a mean nocturnal StcO2 greater than 90%. The PH patients (n = 6), all desaturators, differed from the desaturators with no PH (n = 12), and from ND (n = 22) in having higher numbers of desaturation dips, longer durations of dips, and lower mean nocturnal arterial oxygen saturation (SaO2). We conclude that a causal relation between nocturnal desaturation and permanent PH is very likely. Further studies are needed to see whether oxygen therapy can prevent PH in these patients.

Blood Gas Monitoring, Transcutaneous↗
PubMed1990

Nocturnal hypoxemia and long-term oxygen therapy in COPD patients with daytime PaO2 60-70 mmHg.

Six European treatment centers contributed to a controlled trial to study nocturnal hypoxemia in COPD patients having daytime PaO2 of 60-70 mmHg. The trial is composed of two parts: first, patients inclusion, taking men aged under 70 years, excluding sleep apnea syndrome and all other concomitant pathologies leading to nocturnal desaturation. We described this population and determined the frequency and degree of nocturnal desaturation. Correlations between different daytime and sleep parameters have also been established. The second part concerns the study of the two sub-populations of nocturnal desaturators and nondesaturators. This is followed by random allocation of the desaturators to oxygen or no oxygen treatment. We defined significant nocturnal desaturation as cumulated unsaturation period, exceeding 30% of total time, in bed spent under SaO2 lower than 90%. Twenty out of 46 patients were desaturators (43%). Only the first part is dealt with in this article.

Aged↗
PubMed1989

[Chronic obstructive bronchopneumopathies. Changes in carbon dioxide pressure during sleep in environmental air and with oxygen].

The effects of oxygen administration were studied in 10 patients with severe obstructive lung disease. Sleep variable and gas exchanges were measured during two nights: one when they were breathing environmental air, the other when they were receiving oxygen. Carbon dioxide saturation and partial pressure measured by the transcutaneous method were continuously recorded. Sleep was perturbed in all patients, but despite wide interindividual variations its amount and quality were improved by oxygen. None of the patients had sleep apnoea syndrome. Oxygen administration was accompanied by a nocturnal increase in carbon dioxide pressure that was about twice as high as that observed under environmental air. Thus, in patients with chronic obstructive lung disease without concomitant infection suppression of the hypoxic stimulus by oxygen therapy seems to result in an increase in carbon dioxide partial pressure identical with the increase produced by sleep alone. Correlations between diurnal and nocturnal oxygen saturation and carbon dioxide partial pressure indicate that patients with the highest degree of hypoxia and hypercapnia in daytime have the most severe nocturnal blood gas disorders.

Blood Gas Monitoring, Transcutaneous↗
PubMed1989

The SaO2/t diagram as a useful means to express nocturnal hypoxemia.

The computerization of SaO2 recording during polysomnographic monitoring allows the construction of a diagram expressing the percentage of TIB spent at different steps in saturation. We studied the value of this diagram in three groups of male patients: (1) nine healthy subjects (all volunteers); (2) 25 patients with COPD who had a mean daily SaO2 of 92.3 +/- 1.3 percent; and (3) 25 patients with SAS who had a mean daily SaO2 of 92.1 +/- 1.4 percent. The results show the existence of a discriminating quality in the diagram's morphology, the existence of strong correlations (p less than 0.01) between the percentage of TIB spent at SaO2 less than 85 percent, and the total duration of the desaturation dips.

Aged↗
PubMed1989

Selection of patients for long-term oxygen therapy (LTO).

Serial blood gas measurement must be made for at least three months following an acute exacerbation of chronic obstructive pulmonary disease, to secure stable arterial oxygen tension (PaO2) values. The borderline indications of oxygen therapy concern the patients who have PaO2 over 8 kPa (60 mmHg), but have nocturnal hypoxaemia and/or pulmonary hypertension. The indications of specific drugs such as almitrine are still subject to discussion. The presence of obstructive sleep apnoeas together with ventilatory troubles related to chronic obstructive lung disease (overlap syndrome), is associated with many diagnostic and therapeutic problems.

Blood Gas Analysis↗
PubMed1986

Three-month follow-up of arterial blood gas determinations in candidates for long-term oxygen therapy. A multicentric study.

One hundred seventeen patients with severe chronic obstructive pulmonary disease whose PaO2 in a stable clinical state ranged from 41 to 59 mmHg, were included in a multicentric controlled study on the effects of long-term O2 therapy (LTO), and the results of the 3-month probationary period are given here. Arterial blood gases were checked every month in order to assess the stability of hypoxemia. Time 0 represented the beginning and T3 the end of the probationary period. Patients whose PaO2 at T3 was still between 41 and 59 mmHg could be accepted for the long-term study (Group A), whereas patients whose PaO2 had increased over 59 mmHg were excluded (Group B). Only 77 patients could be followed up regularly from T0 to T3 (40 patients were lost to follow-up, missed some visits, or suffered from acute exacerbations of the disease) and 23 of them had a PaO2 at T3 that exceeded 59 mmHg (Group B), allowing the inclusion of 54 patients (Group A) in the long-term study. Patients in Groups A and B did not differ with regard to pulmonary volumes, PaCO2 at T0 or a past history of right heart failure. Arterial O2 tension at T0 was slightly and significantly (p less than 0.02) lower in Group A (51.3 +/- 5.5 mmHg) than in Group B (54.5 +/- 3.8 mmHg), but there was an important overlapping of individual results from one group to another.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗