Prevalence and predictive factors of sleep apnoea syndrome in type 2 diabetic patients

AIM

This study aimed to assess the prevalence and characteristics of sleep apnoea syndrome (SAS) in patients hospitalized for poorly controlled type 2 diabetes.

METHODS

An overnight ventilatory polygraphic study was systematically performed in 303 consecutive patients.

RESULTS

Overall, 34% of these patients had mild SAS, as defined by a respiratory disturbance index (RDI) of 5-15; 19% had moderate SAS (RDI: 16-29) and 10% had severe SAS (RDI>or=30). The SAS was obstructive in 99% of the apnoeic patients. The percentage of patients with excessive daytime sleepiness (Epworth sleepiness scale>10), fatigue or nocturia did not significantly differ among patients with severe, moderate or mild SAS versus non-apnoeic patients. The percentage of patients who snored was significantly higher in patients with severe or moderate SAS versus non-apnoeic patients. HbA(1c), duration of diabetes and the prevalences of microalbuminuria, retinopathy and peripheral neuropathy did not significantly differ among patients with severe, moderate or mild SAS versus non-apnoeic patients. However, patients with severe or moderate SAS had significantly higher values for body mass index, waist circumference and neck circumference than non-apnoeic patients.

CONCLUSION

In type 2 diabetic patients with poor diabetic control, obstructive SAS is highly prevalent and related to abdominal obesity, and should be systematically screened for, as it cannot be predicted by the clinical data.

Structural and functional arterial properties in patients with obstructive sleep apnoea syndrome and cardiovascular comorbidities

The increased severity of obstructive sleep apnoea syndrome (OSAS) is associated with a parallel increase in the incidence of cardiovascular events. Whether the increased severity of OSAS is in fact associated with impaired arterial properties has never been thoroughly studied. In patients with OSAS who carry a high burden of cardiovascular risk factors, we investigated whether the severity of OSAS is associated with deterioration in the arterial properties, independent of classical cardiovascular risk factors. In 74 consecutive patients with OSAS, we non-invasively assessed, by means of tonometry and high-resolution ultrasound: carotid intima-media thickness (IMT), carotid diameter and plaques, carotid-femoral pulse wave velocity (PWV), central augmentation index (AI) and central blood pressures. The respiratory disturbance index was an independent predictor of IMT and PWV but not of carotid plaques, carotid diameter, AI or central blood pressures. Several parameters of nocturnal hypoxaemia were independently correlated with carotid IMT and PWV. In conclusion, arterial stiffening and thickening are modulated by the severity of OSAS, independently from age and cardiovascular risk factors.

Nutritional depletion in patients on long-term oxygen therapy and/or home mechanical ventilation

The purpose of this study was to estimate the prevalence of malnutrition in outpatients on long-term oxygen therapy or home mechanical ventilation, to determine the relationships between malnutrition and impairment/disability and smoking and also to identify relevant tools for routine nutritional assessment. In 744 patients (M:F 1.68, aged 65+/-15 yrs) with chronic obstructive pulmonary disease (COPD, 40%), restrictive disorders (27%), mixed respiratory failure (15%), neuromuscular diseases (13%) and bronchiectasis (5%), body mass index (BMI), fat-free mass (FFM), serum albumin, transthyretin, 6-min walking test, forced vital capacity (FVC), forced expiratory volume in one second (FEV1) and blood gases were recorded. FFM was the most sensitive parameter for detecting malnutrition, being abnormal in 53.6% of patients, while BMI was <20 in 23.2%, serum albumin <35 g x L(-1) in 20.7%, and serum transthyretin <200 mg x L(-1) in 20%. FFM depletion predominated in neuromuscular, bronchiectasis and restrictive disorders. BMI and FFM were correlated with FEV1, FVC and 6-min walking test. In multivariate analysis a BMI<20 was related to FEV1 and smoking habits, and a low FFM to smoking, FEV1 and female sex. Malnutrition is highly prevalent in home-assisted respiratory patients and is related to causal disease, forced expiratory volume in one second, smoking and disability. Fat-free mass appeared to be the most sensitive and relevant nutritional parameter according to impairment and disability.

[Sleep apnea syndrome and obesity]

Obesity is a main risk factor for sleep apnea syndrome (SAS). The prevalence of SAS is especially high in massive obesity and in visceral obesity. The mechanisms of obstructive apneas in obesity are poorly known, but an increase in upper airway collapsibility probably plays an important role. Several cardiorespiratory complications of SAS, especially systemic arterial hypertension, diurnal alveolar hypoventilation and pulmonary arterial hypertension, are more frequent and more severe in obese patients. An important weight loss resulting from surgical treatment of obesity is often associated with a dramatic decrease in apnea-hypopnea index in patients with massive obesity. In patients with moderate obesity, dietary weight loss is associated with varying degrees of improvement in SAS. Pharyngoplasty and anterior mandibular positioning devices have a low success rate in patients with massive obesity. Nasal continuous positive airway pressure is often the only effective treatment in obese SAS patients.

[Acute asthma attack]

A severe form of exacerbation of asthma, AAA is defined by the presence of a least one sign of clinical severity during the attack. AAA is often preceded by prodromal symptoms that should indicate the need to increase maintenance treatment and eliminate possible triggering factors. Initial treatment of AAA should be made as early as possible and should associate high-dose oxygen, nebulisations of beta-2-agonists and corticosteroid infusion. The immediate prognosis of AAA is particularly related to the initial response to appropriate treatment. When objective improvement criteria are met, discharge can be considered, with short-term outpatient corticosteroid treatment. In more severe stages, beta-2 agonists and anti-cholinergic agent nebulisations are useful. The interest of using other bronchodilators (adrenalin, theophylline) is debated. In case of very severe asthma attack, inhalation of a mixture of helium and oxygen can avoid the need for intubation and mechanical ventilation. Subsequent to AAA, rehabilitation and pulmonary follow-up are indicated in order to prevent recurrence.

[Nutrition and chronic respiratory failure]

Protein calorie malnutrition is frequently observed in patients with chronic obstructive pulmonary disease (COPD). The main mechanism is hypermetabolism essentially resulting from increased oxygen consumption of the respiratory muscles. Malnutrition is associated with poor prognosis, irrespective of age and respiratory function impairment. Malnutrition has several harmful consequences on the respiratory system: atrophy and decreased strength of the respiratory muscles, decreased exercise performance, decreased quality of life, and likely increased risk of community-acquired and nosocomial pneumonia. A long-duration oral supplementation may improve the nutritional status and exercise tolerance in ambulatory COPD patients. The interest of anabolic drugs, especially recombinant growth hormone, has not been demonstrated in malnourished COPD patients.

Pulmonary arterial hypertension in patients with sleep apnoea syndrome

BACKGROUND

Pulmonary arterial hypertension (PAH) in patients with sleep apnoea syndrome (SAS) is classically ascribed to associated chronic obstructive pulmonary disease (COPD). The aim of this retrospective study was to evaluate the possible occurrence of PAH as a complication of SAS in patients without COPD.

METHODS

Right heart catheterisation was performed in 44 patients with SAS and without COPD confirmed by polysomnography (apnoea index >5/h) admitted for the administration of nasal continuous positive airway pressure (CPAP).

RESULTS

Precapillary PAH, defined as mean pulmonary arterial pressure of >20 mm Hg with pulmonary capillary wedge pressure <15 mm Hg, was observed in 12/44 (27%) patients with SAS. There were no significant differences in apnoea index between patients with (PAH+) and those without PAH (PAH-) (42.6 (26.3) versus 35.8 (21.7) apnoeas/h). The PAH+ group differed significantly from the PAH- group in the following respects: lower daytime arterial oxygen tension (PaO(2)) (9.6 (1.1) versus 11.3 (1.5) kPa, p=0.0006); higher daytime arterial carbon dioxide tension (PaCO(2)) (5.8 (0.5) versus 5.3 (0.5) kPa, p=0.002); more severe nocturnal hypoxaemia with a higher percentage of total sleep time spent at SaO(2) <80% (32.2 (28.5)% versus 10.7 (18.8)%, p=0.005); and higher body mass index (BMI) (37.4 (6) versus 30.3 (6.7) kg/m(2), p=0.002). The PAH+ patients had significantly lower values of vital capacity (VC) (87 (14)% predicted versus 105 (20)% predicted, p=0.005), forced expiratory volume in one second (FEV(1)) (82 (14)% predicted versus 101 (17)% predicted, p=0.001), expiratory reserve volume (40 (16)% predicted versus 77 (41)% predicted, p=0.003), and total lung capacity (87 (13)% predicted versus 98 (18)% predicted, p=0.04). Stepwise multiple regression analysis showed that mean pulmonary artery pressure (PAPm) was positively correlated with BMI and negatively with PaO(2).

CONCLUSION

Pulmonary arterial hypertension is frequently observed in patients with SAS, even when COPD is absent, and appears to be related to the severity of obesity and its respiratory mechanical consequences.

A noninvasive diagnostic strategy including spiral computed tomography in patients with suspected pulmonary embolism

We conducted a study to evaluate a noninvasive strategy including spiral computed tomography (CT) in patients with suspected pulmonary embolism (PE). We systematically performed spiral CT, ventilation/perfusion lung scanning, and D-dimer (DD) measurement (VIDAS test), and in some cases (with a normal CT with nondiagnostic lung scan and increased DD) performed venous ultrasonography (US) on 247 consecutive patients with clinically suspected PE in our hospital. Patients in whom PE was deemed absent were not given anticoagulants. All patients were followed for 3 mo. The prevalence of PE in the 228 patients who could be evaluated was 42% (96 of 228). PE was confirmed by spiral CT in 73% of the patients, by a high-probability lung scan in 4%, and by findings on US in 23%. PE was ruled out by a normal lung scan in 14% of the patients, by a normal DD concentration (< 500 ng/ml) in 31%, by an obvious differential diagnosis on spiral CT in 18%, by a similar prior lung scan in 11%, and by the combination of normal spiral CT findings, a nondiagnostic lung scan, a DD concentration > 500 ng/ml, and normal US in 26%. Pulmonary angiography was performed in only two patients, both of whom had a normal spiral CT scan and a high-probability lung scan, and was normal. The 3-mo risk of thromboembolism in patients not given anticoagulants, based on the results of the diagnostic protocol, was 1.7% (95% confidence interval: 1.5 to 2.3%). There were no deaths. The noninvasive strategy of combining spiral CT, lung scanning, DD measurement, and in some cases US, in patients with suspected PE yielded a definite diagnosis in 99% of patients, and appeared to be safe.

[Influence of nutritional status on development of nosocomial pneumonia in case of acute decompensation of chronic obstructive pulmonary diseases]

OBJECTIVE

The aim of this retrospective study was to assess the incidence of nutritional status on the development of nosocomial pneumonia in patients with chronic obstructive pulmonary disease (COPD) suffering an acute episode of respiratory failure requiring ventilatory assistance.

PATIENTS AND METHODS

The study included 48 patients with COPD who were hospitalized in an intensive care unit for acute respiratory failure requiring ventilatory assistance. Nutritional status was assessed within 24 hours of admission to the intensive care unit. Body weight, tricipital skin fold, brachial muscle circumference, creatinuria-waist index, plasma levels of albumin, transferrin, transthyretin and retinol-binding protein, the Multitest and lymphocyte counts were recorded. The diagnosis of nosocomial pneumonia was based on recognized criteria: occurrence more than 48 hours after admission, Andrews' criteria for bacterial pneumonia and bacteriological proof.

RESULTS

Nineteen of the 48 patients developed nosocomial pneumonia. The nutritional parameters at admission to intensive care were not significantly different between patients who developed nosocomial pneumonia and those who remained free of lung infection. The duration of ventilatory assistance and total stay in the intensive care unit were significantly longer in patients who developed nosocomial pneumonia.

CONCLUSION

This study showed that in patients with COPD who undergo ventilatory assistance for acute decompensation, the development of nosocomial pneumonia was not correlated with nutritional status admission.

[Body composition in chronic obstructive lung patients. Comparison of bioelectric impedance and anthropometry]

Malnutrition is associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). Body weight is not a reliable evaluation criterium. Body composition which is more useful can be determined routinely using 2 techniques: skinfold thickness anthropometry (Ant) and bioelectrical impedance analysis (BIA). The validity of this last technique has not been demonstrated in patients with COPD. Fat-free mass (FFM) in 58 patients (51 men, 7 women) with stable COPD (FEV1 < 50% of predicted value) was assessed using the 4-skinfold-thickness method (Ant) and BIA (Imp). Statistical analysis included correlation analysis, intraclass correlation coefficient, and the Bland and Altman analysis. Imp-FFM and Ant-FFM correlated well (r = 0.920; p < 0.0001). Intraclass correlation coefficient was high (rI = 0.9065). However, the values were scattered and there was a systematic bias (significant linear regression between the difference in estimates obtained by the 2 methods and the means). As anthropometric measurements are not reliable in the elderly patients, our results suggest that BIA could be a useful tool to determine FFM in patients with COPD. Its validity still has to be tested against a reference method.

Bioelectrical impedance analysis in estimating nutritional status and outcome of patients with chronic obstructive pulmonary disease and acute respiratory failure

OBJECTIVE

To evaluate bioelectrical impedance analysis (BIA) in estimating the nutritional status and outcome of patients with chronic obstructive pulmonary disease (COPD) and acute respiratory failure (ARF) in comparison with measurements of anthropometric parameters and plasma levels of visceral proteins.

DESIGN

Retrospective study.

SETTING

A ten-bed intensive care unit (ICU) in a university teaching hospital.

PATIENTS

51 COPD patients with ARF in whom BIA data, anthropometric parameters, and measurements of visceral proteins were available.

MEASUREMENTS AND RESULTS

BIA results in patients requiring mechanical ventilation (MV) vs. those who did not showed lower active cell mass (ACM; 37.5 +/- 6.5% vs. 42.4 +/- 7.2% body weight, P = 0.01) and a higher extra-/intracellular water volume ratio (ECW/ICW; 1.25 +/- 0.2 vs. 1.04 +/- 0.2, P = 0.0001), suggesting a more severe alteration in the nutritional status among those on MV. Anthropometric data showed the opposite results, since body weight, body mass index (BMI), triceps skinfold thickness (TSF), and fat mass were significantly higher in the invasively ventilated patients, whereas middle-arm muscle circumference (MAMC) did not differ between the two groups. The marked inflation of the extracellular compartment (ECW, ECW/ICW) that was well shown by BIA in the invasively ventilated patients presumably lead to inaccurate anthropometric results (overestimation of TSF and fat mass, and erroneous measure of MAMC). A higher death rate (38% vs. 0%, P = 0.01) was observed in the patients with ACM depletion (ACM < or = 40.6% body weight, n = 26) than in those without ACM depletion (n = 25). Low albumin level (< 30 g/l) was associated with increased mortality (33% vs. 7%, P = 0.04), but the differences in the other biological and anthropometric parameters (prealbumin and transferrin levels, body weight, BMI, TSF, MAMC, fat mass, and fat-free mass) were not associated with mortality.

CONCLUSION

This study suggests that the decrease in BIA-derived ACM is a good indication of malnutrition and of poor outcome in COPD patients with ARF.

[Value of Holter ECG in the diagnosis of sleep apnea syndrome in patients with massive obesity]

OBJECTIVE

Assess the diagnostic contribution of cyclic nocturnal variations in heart rate in sleep apnea syndrome.

PATIENTS AND METHODS

Holter recordings performed in a population of 30 patients with massive obesity defined as a body mass index greater than 40 kg/m2 and sleep apnea syndrome defined by an apnea index greater than 5 apneas per hour were analyzed retrospectively. The control group was composed of 15 patients with massive obesity but without sleep apnea syndrome. High variability in nocturnal heart rate was assessed using a visual criterion defined as repeated episodes of progressive reduction in heart rate followed by a sudden acceleration reaching a difference of 30 bpm between the highest and lowest heart rate and occurring at least 5 times during one consecutive hour of recording.

RESULTS

Increased nocturnal variability in heart rate was evidenced in all the patients with sleep apnea syndrome (30/30) but was not observed in any of the control subjects (0/15).

CONCLUSION

These results suggest that Holter recordings can be a useful tool for the diagnosis of sleep apnea syndrome.

Modern strategy for diagnosis and treatment of pulmonary embolism

Various techniques are available for the diagnosis of pulmonary embolism (PE), including pulmonary angiography, perfusion-ventilation lung scanning, D-dimer measurement, venous ultrasonography and, most recently, helical computerized tomography of the chest. The advantages and disadvantages of these techniques, used alone or in combination, are briefly discussed. Studies have indicated that treatment with low-molecular-weight heparin (LMWH), as well as being more convenient to administer, is as safe and effective as standard heparin therapy in acute PE. However, the efficacy and safety of LMWH in patients with acute PE and haemodynamic instability requires verification. Finally, the indications of inferior vena caval filters and thrombolytic therapy are outlined.

[The value of biological and clinical signs of pulmonary embolism]

Pulmonary embolism (PE) is often underdiagnosed, mainly because it is not thought of. Its clinical signs are not highly specific and are encountered in a wide range of pulmonary diseases. Certain symptoms and signs, particularly when combined, are suggestive of PE: unexplained dyspnea, pleuretic pain with or without hemoptysis, tachypnea, etc. but they are not pathognomonic. Routine laboratory investigations such as arterial blood gas analysis, total blood cell count, serum LDH, etc. ... contribute poorly to making the diagnosis. D-dimers are fibrin degradation products. It has now been made possible to rule out PE in almost 20% of suspected cases, when plasma D-dimers levels are lower than 500 ng/ml, using the ELISA technique, with a very high sensitivity rate (98%). On the other hand, their specificity and positive predictive value are low (< 50%) and under no circumstances should their measurement be used to confirm the diagnosis of PE. This test is time-consuming, but new faster techniques seem to be promising.

[Spontaneous bilateral chylothorax revealing disseminated tuberculosis complicated by massive pulmonary embolism]

We report a case of bilateral chylothorax revealing diffuse tuberculosis. The clinical presentation was complicated by the apparition of a massive acute pulmonary embolism and an acute respiratory distress syndrome. Mycobacterium tuberculosis was isolated from the cultures of the bronchi aspiration of the bronchoscopic examination. With antituberculous chemotherapy, the course of the chylothorax was satisfactory.

[Methods of nutritional assessment in chronic obstructive lung diseases]

A poor nutritional state is often encountered in the course of chronic obstructive lung disease (COLD) and worsens the prognosis. The methods used to assess nutritional status proposed in the literature vary greatly. We detail here the methods used in clinical practice and in research, describing results obtained in patients with COLD. Appropriate routine tests are discussed. Body weight should be followed in this population, but weight loss may be masked by sodium-water retention. Bioelectric impedancemetry or biphotonic absorptiometry are used to define body composition in patients with COLD. Lean mass can be measured with the creatinine/height index but is difficult in the ambulatory patient. Plasma levels of visceral proteins are often normal and do not appear to be useful markers in these patients. Immunology tests (delayed hypersensitivity, total lymphocyte counts) are not sensitive screening tests. An evaluation of skeletal muscle function using the walking test or an exercise test is recommended before starting a renutrition program and to evaluate its efficacy.

[Pulmonary embolism. The role of computed tomography angiography]

NONINVASIVE PROCEDURE: Helical CT angiography is a noninvasive procedure whose only relative contraindications are renal insufficiency and iodine allergy. MASSIVE PULMONARY EMBOLISM: If a massive pulmonary embolism is suspected, helical CT angiography is the examination of choice because of its high accuracy in detecting proximal thrombi and its safety profile. NON-MASSIVE PULMONARY EMBOLISM: If a non massive pulmonary embolism is suspected, helical CT angiography, because of its high specificity, can be the first examination instead of scintigraphy. If a thrombus is depicted by CT, the diagnosis of pulmonary embolism is confirmed and treatment is started. If no thrombus is visualized by CT, pulmonary embolism can be ruled out in most cases. In case of doubt, another noninvasive procedure should be performed. Angiography should be the exception and seldom is needed.

Hyperlactatemia during acute severe asthma

OBJECTIVE

To evaluate arterial lactate levels during treatment of acute severe asthma (ASA) and the prognostic value of arterial hyperlactatemia in ASA.

DESIGN

Prospective study.

SETTING

A respiratory intensive care unit (ICU) of a university hospital.

PATIENTS

29 consecutive patients admitted to the ICU for ASA not intubated on admission and with a peak expiratory flow (PEF) < 150 l/min or an arterial carbondioxide tension (PaCO2) > 40 mm Hg. All patients received standardized treatment during the first 24 h including i.v. and nebulized salbutamol, i.v. theophylline, and dexamethasone.

MEASUREMENTS AND RESULTS

Arterial lactate levels were serially measured by an enzymatic method during the first 24 h following admission. On admission, the mean arterial lactate level was 3.1 +/- 0.38 mmol/l (range 1.1-10.4); 17 patients (59%) had arterial hyperlactatemia with a lactate level > 2 mmol/l. No difference was found in lactate levels between patients with progressively worsening asthma and those with an acute onset of severe asthma. No correlation was found between arterial lactate levels on admission, on the one hand, and respiratory rate (RR), heart rate, PEF, pH, PaCO2, arterial oxygen tension, potassium, phosphorus, creatine kinase, or transaminase values on admission, on the other hand. All patients developed an important but transient increase in arterial lactate levels during treatment, with a peak at 7.72 +/- 0.46 mmol/l and a mean elevation of 4.62 +/- 0.45 mmol/l (range 0.4-12.1), from the initial admission value contrasting with a significant clinical improvement assessed by RR, PEF, and arterial blood gas parameters.

CONCLUSION

This study suggests that, in ASA, arterial hyperlactatemia is frequently present on admission to the ICU. Delayed hyperlactatemia is a constant finding during treatment of ASA. Initial or delayed hyperlactatemia seems of no prognostic value because none of the patients required mechanical ventilation. The effects of therapy for acute asthma on lactate metabolism still need to be studied.

Cardiorespiratory consequences of sleep apnoea syndrome in patients with massive obesity

Assessment of cardiorespiratory consequences of sleep apnoea syndrome (SAS) is difficult owing to confounding factors, especially obesity, that are strongly associated with SAS. This study was designed to assess the cardiorespiratory consequences of SAS by comparing the results of a comprehensive cardiorespiratory evaluation in apnoeic and nonapnoeic patients with massive obesity. In a retrospective chart-review study, we studied 60 patients with massive obesity defined by a body mass index (BMI) >40 kg.m(-2), presenting no chronic respiratory disease, who underwent an extensive assessment of cardiorespiratory consequences of obesity, including overnight polysomnography, lung function tests, arterial blood gas analysis, evaluation of vascular risk factors, myocardial scintigraphy with dipyridamole stress-test, isotopic ventriculography, Doppler echocardiography and Holter electrocardiogram recording. SAS defined by an apnoea + hypopnoea index (AHI) > or = 10 was diagnosed in 42% of patients (25 out of 60). Mean+/-SD AHI of SAS-positive (SAS+) patients was 38+/-24. Age, BMI, ventilatory function parameters, prevalence of smoking history and diabetes mellitus did not differ significantly in SAS+ versus SAS-negative (SAS-) groups. The following complications were observed more frequently in SAS+ than in SAS- patients: daytime hypoxaemia (35 vs 9%, p<0.02), pulmonary arterial hypertension (36 vs 7%, p<0.05) and increased interventricular septal thickness (50 vs 15%, p<0.03). No association was found between SAS on the one hand and systemic arterial hypertension, coronary artery disease, left ventricular dysfunction and nocturnal cardiac arrhythmias on the other. Nocturnal apnoeas in massive obesity may thus be associated with moderate daytime hypoxaemia, mild pulmonary arterial hypertension and moderate left ventricular hypertrophy, but not with severe cardiorespiratory complications.

A comparison of low-molecular-weight heparin with unfractionated heparin for acute pulmonary embolism. The THESEE Study Group. Tinzaparine ou Heparine Standard: Evaluations dans l'Embolie Pulmonaire

BACKGROUND

Low-molecular-weight heparin appears to be at least as effective and safe as standard, unfractionated heparin for the treatment of deep-vein thrombosis, but only limited data are available on the use of low-molecular-weight heparin to treat acute symptomatic pulmonary embolism.

METHODS

We randomly assigned 612 patients with symptomatic pulmonary embolism who did not require thrombolytic therapy or embolectomy to either subcutaneous low-molecular-weight heparin (tinzaparin) given once daily in a fixed dose or adjusted-dose, intravenous unfractionated heparin. Oral anticoagulant therapy was begun between the first and the third day and was given for at least three months. We compared the treatments at day 8 and day 90 with respect to a combined end point of recurrent thromboembolism, major bleeding, and death.

RESULTS

In the first eight days of treatment, 9 of 308 patients assigned to receive unfractionated heparin (2.9 percent) reached at least one of the end points, as compared,with 9 of 304 patients assigned to low-molecular-weight heparin (3.0 percent; absolute difference, 0.1 percentage point; 95 percent confidence interval, -2.7 to 2.6). By day 90, 22 patients assigned to unfractionated heparin (7.1 percent) and 18 patients assigned to low-molecular-weight heparin (5.9 percent) had reached at least one end point (P=0.54; absolute difference, 1.2 percentage points; 95 percent confidence interval, -2.7 to 5.1). The risk of major bleeding was similar in the two treatment groups throughout the study.

CONCLUSIONS

Under the conditions of this study, initial subcutaneous therapy with the low-molecular-weight heparin tinzaparin appeared to be as effective and safe as intravenous unfractionated heparin in patients with acute pulmonary embolism.

Role of the thermic effect of food in malnutrition of patients with chronic obstructive pulmonary disease

Malnutrition in patients with chronic obstructive pulmonary disease (COPD) is classically ascribed to an increased resting energy expenditure (REE) secondary to high cost of breathing. However, malnutrition correlates only weakly with the severity of respiratory dysfunction, which suggests other mechanisms. The aim of the present study was to determine the possible role of diet-induced thermogenesis (DIT). Therefore, we evaluated the relationship between DIT and nutritional status, in particular fat-free mass (FFM) estimated by bioelectrical impedance analysis in 26 patients with stable COPD (mean FEV1 +/- SEM = 36.5 +/- 3.8% of predicted). Ten patients were undernourished (weight < 90% of ideal body weight [IBW] and/or FFM < 69% of IBW), and 16 were normally nourished. Diet-induced thermogenesis was determined by comparing postprandial energy expenditure and REE, the latter being measured after an overnight fast and the former over 4 h after a mixed test meal of 0.4 times REE load. No statistical difference in DIT was found between undernourished and eutrophic patients. There was no relationship between DIT and nutritional or functional parameters, notably FFM. These results suggest that malnutrition is not a consequence of an increased DIT.

[Value of plasma D-dimer assays in the diagnosis of venous thromboembolism]

The diagnostic usefulness of measuring plasma D-dimers using the ELISA method and the latex agglutination test has been prospectively evaluated in 117 patients hospitalized for suspicion of acute venous thrombo-embolism (AVTE): pulmonary embolism was suspected in 80 patients and the remaining 37 had a suspicion of deep vein thrombosis of the lower limbs. The diagnosis of AVTE was confirmed in 50% of the patients, all of whom underwent gold standard invasive investigation i.e. pulmonary angiography and/or contrast venography. The sensitivity, specificity, negative predictive value and positive predictive value of a D-dimers plasma concentration exceeding 500 ng/ml for the diagnosis of AVTE were respectively 98, 58, 97 and 70% when using the ELISA method, and 86, 71, 84 and 75% when using the latex assay. In 47 patients whose lung scans yielded abnormalities of indeterminate probability of pulmonary embolism, the sensitivity of the ELISA method was very high (94%), but that of latex assay was low (67%). Our results demonstrate that measuring the plasma D-dimers by the latex assay should not be used in the diagnosis of AVTE. On the other hand, the ELISA method might be of great interest in the diagnostic strategy of AVTE, as a normal concentration of D-dimers rules out almost definitely the diagnosis of AVTE, and hence, spares from performing invasive investigations.

Bronchial hyperresponsiveness following acute severe asthma

OBJECTIVE

To evaluate bronchial hyperresponsiveness (BHR) early after recovery from acute severe asthma (ASA).

DESIGN

Prospective study including all patients admitted to the intensive care unit (ICU) for ASA over a 12-month period.

SETTING

University teaching ICU and pneumonology department.

PATIENTS

41 consecutive patients admitted to the ICU for ASA. Results were compared with those of a control group with stable asthma and no history of ASA or steroid therapy, matched for sex and age.

MEASUREMENT AND RESULTS

Of the 41 patients, 40 completed respiratory function tests 10 days after ICU admission, and the minimal dose of acetylcholine inducing a fall in forced expiratory volume in 1 s (FEV1) of 20% or more (PD AC) could be determined safely by a novel method in 26 patients with an FEV1 above 60% predicted. PD AC (micrograms) was found to be significantly lower in ASA than in control patients. Very severe BHR (PD AC < or = 100 micrograms) was found in 18 ASA patients, but not in the control patients; 5 ASA versus 12 control patients had marked BHR (100 > PD AC < or = 500 micrograms); and 3 ASA versus 14 control patients had moderate BHR (> 500 micrograms). A similar level of BHR was found in ASA patients with progressive or acute worsening. No correlation was found between PD AC and admission PaCO2 value, admission peak expiratory flow (PEF) value, delay in improvement of PEF, delay in PD AC determination, or prechallenge FEV1 value.

CONCLUSION

BHR measurement is safe soon after an episode of ASA if done with caution. At this time, patients who are free of clinical symptoms and have no significant objective bronchial obstruction appear to have severe bronchial hyper-responsiveness.

[Mechanisms of diurnal hypercapnia in sleep apnea syndromes associated with morbid obesity]

OBJECTIVES

The prevalence and mechanisms of diurnal hypercapnia in subjects with sleep apnea syndrome are not well known, particularly in the morbidly obese.

METHODS

We studied a group of 24 subjects with sleep apnea syndrome and morbid obesity defined as a body mass index greater than 40 kg/m2 and free of chronic respiratory disease.

RESULTS

Hypercapnia (PaCO2 > 42 mmHg) was found in 50% of the subjects. Age, body mass index, waist/hip ratio, apnea index, ratio of maximum forced expiratory volume in one second (FEV1) to vital capacity and expiratory reserve volume were not significantly different between hypercapnic and normocapnic subjects. Total pulmonary capacity, vital capacity and FEV1 were significantly lower in hypercapnic subjects than in normocapnic subjects.

CONCLUSION

These findings suggest that ventilatory restriction plays an important role in the development of diurnal alveolar hypoventilation in subjects with sleep apnea syndrome and morbid obesity.

[Value of the determination of D-dimers in the diagnostic approach of venous thrombo-embolic disorders]

The aim of this study is to evaluate the usefulness of plasma measurements of D-dimer using ELISA method and latex agglutination test in the diagnostic approach of venous thromboembolism. Among 126 patients suspected of pulmonary embolism (80 pat.) or deep venous thrombosis of the legs (46 pat.), the diagnosis of acute venous thromboembolism has been confirmed using gold standard invasive techniques (pulmonary angiography and/or contrast venography) in 49% of them. The sensitivity, specificity, negative predictive value and positive predictive value of a D-dimer plasma concentration above 500 ng/ml, on admission day, for the diagnosis of venous thromboembolism are 98%, 66%, 97%, 74% respectively when using the ELISA method, and 87%, 70%, 85%, 74% respectively when using the latex assay. In the 51 patients with a lung scan showing an indeterminate probability of pulmonary embolism, the sensitivity of the ELISA method is very high (94%) but that of the latex assay is low (67%). The repetition of D-dimer measurement on days 2 and 4 following admission has no significant effect on the sensitivity of the ELISA and latex assays. Our results demonstrate that the measurement of plasma D-dimer concentration using latex assay should not be used in the diagnostic approach of venous thromboembolism because the sensitivity of this test is insufficient for ruling out the presence of the disease. On the opposite, a low concentration of plasma D-dimer measured by the ELISA method might be used to rule out acute venous thromboembolism, and avoid invasive radiological techniques, especially in patients with an indeterminate probability lung scan.

[Artificial nutrition in patients with chronic respiratory insufficiency undergoing surgery]

Denutrition is a common finding in patients with chronic respiratory failure (CRF). Preoperative denutrition increases the risk of nosocomial pneumonia and difficulties in weaning from mechanical ventilation. A preoperative nutritional support may have beneficial effects on respiratory muscles performance. However, prospective studies need to be carried out in patients with CRF to substantiate this hypothesis. Postoperative nutritional support is indicated if weaning from the ventilator is expected to require more than several days, in order to preserve the diaphragmatic function. Lipid-enriched nutrition may have a beneficial effect, when energy supply is high, as the resulting decrease in CO2 production may facilitate the weaning from the ventilator. A beneficial effect of branched-chain amino acid-enriched solutions has not been demonstrated in patients with CRF.

Mycobacterium kansasii infection presenting as an endobronchial tumor in a patient with the acquired immune deficiency syndrome

We report a case of Mycobacterium kansasii endobronchial infection presenting as a tumor obstructing 2 segmental bronchi in a patient with the acquired immune deficiency syndrome. Biopsies of the lesions revealed granuloma with acid-fast organisms. Culture grew M. kansasii. To our knowledge, this is the first case of M. Kansasii infection presenting with endobronchial mass.

Thrombotic primary pulmonary hypertension in an HIV+ patient

We report a case of severe primary pulmonary hypertension occurring in an HIV+ patient in whom lung biopsy and post-mortem examination were consistent with thrombotic pulmonary arteriopathy. To the best of our knowledge, this histological pattern has not been previously reported in HIV+ patients with primary pulmonary hypertension.

[Respiratory function in massive obesity]

Massive obesity may be accompanied by severe and sometimes lethal respiratory complications. The restrictive ventilatory deficit which results from a decrease in thoracic wall compliance and perhaps also from diaphragmatic dysfunction is more severe in males and in subjects with abdominal obesity. Diurnal hypoxaemia results from 2 mechanisms: diminution of the ventilation/perfusion ratio at the base of the lung, and alveolar hypoventilation. Hypercapnia is a fairly frequent complication of massive obesity. Although usually moderate, hypercapnia is a major indicator as it is very often associated with sleep apnoea syndrome. The most severe respiratory complication of massive obesity is this syndrome which must be looked for systematically by questioning the patient and her husband or his wife before serious cardiopulmonary and neuropsychic disorders appear. The effects of weight loss of nocturnal apnoea are inconsistent and variable. Continuous positive pressure ventilation by means of a nasal mask is the choice treatment of sleep apnoea syndrome, especially since the results of rhino-laryngeal surgery are often disappointing.

[Cardio-respiratory complications of sleep apnea in obese patients]

The cardio-respiratory complications of sleep apnea syndrome have been prospectively assessed in 60 patients with massive obesity and free of chronic obstructive lung disease while the associated cardiovascular diseases and the alterations of pulmonary function were taken into account. These cardio-respiratory complications were observed only in patients with a number of apneas per hour of sleep greater than 20. The sleep apneas induced nocturnal hypoxemia that is frequently severe and independently correlated to the apnea index, diurnal hypoxemia and hypercapnia that are usually moderate, and presumably left ventricular hypertrophy that is not related to the development of daytime hypertension. However the nocturnal apneas were not associated with the development of an impairment of right or left ventricular function, or with the occurrence of cardiac arrhythmias or conduction disturbances. The absence of severe cardiac complications in this study may be related to the fact that the patients were relatively young and that the sleep apnea syndrome was diagnosed at an early stage of evolution. The findings of this study could help to define a more rationale approach in several therapeutic indications of sleep apnea syndrome.

Nutritional status of patients with chronic obstructive pulmonary disease and acute respiratory failure

The prevalence and features of malnutrition in COPD patients have been studied extensively in stable conditions but are poorly defined in the presence of acute respiratory failure (ARF). Nutritional status was prospectively assessed, on hospital admission, in 50 consecutive COPD patients presenting with ARF, 27 of them requiring mechanical ventilation (MV). Malnutrition, defined on a multiparameter nutritional index, was observed in 60 percent (30/50) of all patients, and in 39 percent (13/33) of those whose body weight was equal to or above 90 percent ideal body weight (IBW). Malnutrition was more frequent in those patients who required MV than in those who did not (74 percent vs 43 percent, p < 0.05). Subcutaneous fat stores were decreased (triceps skinfold thickness [TSF] < 80 percent pred) in 68 percent of patients, and markedly depleted (TSF < 60 percent pred) in 52 percent of them. The indices of lean body mass, ie, mid-arm muscle circumference (MAMC) and creatinine height index (CHI) were decreased in, respectively, 42 percent and 71 percent of patients, but MAMC was severely depressed (< 60 percent pred) in only 6 percent of them. A severe decrease of prealbumin (< 100 mg/L), retinol-binding-protein (< 20 mg/L), and albumin (< 20 g/L) serum concentrations was observed in, respectively, 22 percent, 28 percent, and 4 percent of patients. These results suggest that an assessment of nutritional status using a multiparameter approach should be systematically performed in COPD patients with ARF, especially in those requiring MV, as malnutrition may have deleterious effects on weaning off MV.

[Respiratory complications of massive obesity]

Massive obesity may lead to serious, and sometimes fatal, respiratory complications. Alterations of ventilatory mechanics and function are well known; they include a decrease in respiratory compliance, an increase in ventilatory work and a restrictive pulmonary disease. Hypoxemia is rather due to an impaired ventilation/perfusion ratio than to alveolar hypoventilation. Sleep Apnea Syndrome (SAS) is very frequent in excessively obese patients. These subjects with daytime hypersomnolence should be systematically screened for SAS before the occurrence of life-threatening complications. Continuous positive airway pressure ventilation through a nasal mask is the treatment of choice of SAS especially since the results of body weight reduction and ENT surgery are inconstant and variable in these patients.

[Severe methotrexate poisoning]

Methotrexate toxicity is rare but extremely severe. When complete, it consists of ulcerations of the gastrointestinal mucosae responsible for necrotizing enteritis, erythroderma, bone marrow aplasia, interstitial pneumonia, hepatitis and organic renal failure with diuresis. Toxicity is facilitated by pre-existing renal impairment, third sector and abstention or underdosage of foliculinic acid prescribed as antagonist. The diagnosis rests on serum assays, the results of which must be interpreted taking into account the assay method and the time elapsed between the injection of methotrexate and its assay in serum. The multivisceral pathology observed may totally regress, as in the case reported here. Treatment is based on symptomatic measures, starting with maintenance of an abundant and alkaline diuresis, and on the parenteral administration of folinic acid in doses that vary with the authors.

Computed tomography and magnetic resonance findings in lipoid pneumonia

A case of exogenous lipoid pneumonia was documented by computed tomography and magnetic resonance imaging. Although strongly suggesting the presence of fat on T1 weighted images, magnetic resonance does not produce images specific for this condition. Computed tomography is the best imaging modality for its diagnosis.

[Diagnosis of pulmonary artery hypertensions]

The clinical signs of pulmonary arterial hypertension (PAH) lack specificity and do not permit an early diagnosis. Right heart catheterization is still the reference method to confirm the diagnosis of PAH and assess its severity. Numerous non-invasive methods have been used to evaluate PAH. The value of conventional non-invasive methods is limited by a high failure rate (standard echocardiography in patients with chronic respiratory disease), a mediocre sensitivity, notably in detecting moderate PAH (electrocardiography, radiography of the chest, myocardial thalium scintigraphy) or a poor specificity (isotopic angiography). Nowadays, Doppler-echocardiography is the most interesting method since it has a significant success rate and high sensitivity and specificity in detecting PAH. However, this method fails to predict very accuratly the pulmonary arterial pressure in individual patients. The systematic combination of several Doppler ultrasound methods should improve the efficacy of Doppler-echocardiography in evaluating the severity of PAH.

[Monitoring of small cell bronchopulmonary cancer by bronchial biopsies]

This retrospective study of 149 patients with small cell lung cancer highlights the value of bronchial endoscopies combined with biopsies for the follow-up of these cases. A control endoscopy performed during the third month showed that macroscopic lesions had completely disappeared in 42 percent of the patients. Each subsequent endoscopy offered a probability rising from 20 to 50 percent of diagnosing a recurrence in the patients explored. Our study particularly demonstrates the usefulness of bronchial biopsy at the initial site of the lesion, even when the bronchial mucosa seems to have returned to normal, since this biopsy is positive in 4.5 percent of the cases.

Continuous infusion of high-dose metoclopramide: comparison of pharmacokinetically adjusted and standard doses for the control of cisplatin-induced acute emesis

Metoclopramide was administered by continuous infusion to two groups each of 14 patients on chemotherapy, randomized to receive either doses adjusted to individual pharmacokinetic parameters or doses adjusted as usual to body weight. The mean plasma concentration at the end of the infusion in the adjusted group was 1.01 mg.l-1, close to that aimed for (1.20 mg.l-1). It was significantly different from that in the other group. v 0.54 mg.l-1. Antiemetic efficacy, defined as less than or equal to 2 emetic events in the 24 h following cisplatin, was similar in both groups (being found in 12/14 (86%) and 10/14 patients (71%), respectively). Analysis of the cumulative percentage of responders according to plasma concentration showed a clear plasma concentration-effect relationship. Routine MCP pharmacokinetic dosage adjustment is not indicated, but this therapeutic approach can be used to optimize antiemetic therapy in poor responder patients.

Doppler echocardiographic evaluation of pulmonary artery pressure in chronic obstructive pulmonary disease. A European multicentre study. Working Group on Noninvasive Evaluation of Pulmonary Artery Pressure. European Office of the World Health Organization, Copenhagen

The feasibility, reproducibility and reliability of Doppler echocardiography in evaluation of pulmonary artery pressure in patients with chronic obstructive pulmonary disease (COPD) were determined in a multicentre study. In 100 COPD patients with mean pulmonary artery pressure ranging from 10 to 62 mmHg at cardiac catheterization, pulmonary pressure estimation was attempted by four Doppler echocardiographic methods. These methods comprised the calculation of transtricuspid and transpulmonary pressure gradients from Doppler-detected tricuspid or pulmonary regurgitation, the evaluation of right ventricular outflow tract velocity profiles with the measurement of right ventricular systolic time intervals and the measurement of the right ventricular isovolumic relaxation time. In 98 (98%) patients at least one of the methods could be employed. A tricuspid regurgitation jet was detected in 47 (47%) patients but its quality was adequate for measurement in 30 (30%). Pulmonary regurgitation jet velocity was measured only in five cases. The standard error of estimate in testing intra- and interobserver reproducibility of Doppler systolic time intervals was less than 5%. The predictive value of right ventricular outflow tract acceleration time less than 90 ms in the identification of patients with mean pulmonary artery pressure greater than 20 mmHg was 80%. Of Doppler echocardiographic data, best correlations with mean pulmonary artery pressure were found for the transtricupid gradient (r = 0.73, SEE = 7.4 mmHg), for the right ventricular acceleration time (r = 0.65, SEE = 8 mmHg) and right ventricular isovolumic relaxation time (r = 0.61, SEE = 8.5 mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)

[Quantitative analysis of systolic function of the right ventricule by Doppler echocardiography]

The recording of the velocity of tricuspid valve regurgitation by continuous wave Doppler enables the calculation of the instantaneous systolic pressure gradient between the right ventricle and right atrium. As right atrial pressure is relatively constant, the rate of acceleration of the regurgitant jet reflects the quality of the rise in pressure in the right ventricle in early diastole, and therefore right ventricular contractility. The authors studied 3 Doppler parameters of the rate of velocity increase of the tricuspid regurgitation; the maximum rate of acceleration (dV/dt max), the maximum derivative of the pressure (dP/dt max) and the mean rate of increase in pressure (T). The interobserver variability of these indices is low (r greater than 0.96); reproducibility is good in patients with sinus rhythm but mediocre in atrial fibrillation. The comparison of the Doppler indices with the right ventricular isotopic fraction in 26 patients with tricuspid regurgitation showed a good correlation (dV/dt max, r = 0.79, p less than 0.0001; dP/dt max, r = 0.69, p less than 0.0001; T, r = 0.60, p = 0.0012). These results show that right ventricular systolic function can be evaluated by continuous wave cardiac Doppler by recording the spectral envelope of tricuspid regurgitation.