Respiratory sound analysis in the era of evidence-based medicine and the world of medicine 2.0

OBJECTIVE

This paper describes the state of the art, scientific publications, and ongoing research related to the methods of analysis of respiratory sounds.

METHODS AND MATERIAL

Narrative review of the current medical and technological literature using Pubmed and personal experience.

RESULTS

We outline the various techniques that are currently being used to collect auscultation sounds and provide a physical description of known pathological sounds for which automatic detection tools have been developed. Modern tools are based on artificial intelligence and techniques such as artificial neural networks, fuzzy systems, and genetic algorithms.

CONCLUSION

The next step will consist of finding new markers to increase the efficiency of decision-aiding algorithms and tools.

[Vocal cord dyskinesia and/or asthma]

INTRODUCTION

Vocal cord dyskinesia or vocal cord dysfunction (VCD) is characterized by intermittent abnormal adduction of the vocal cords leading to airflow limitation at the level of the larynx, in the absence of local organic disease. It may occur in isolation or in association with asthma. The pathophysiology is complex and poorly understood. Wheeze, stridor or apparent upper airway obstruction are the most common symptoms. It occurs in a wide age range, more commonly in women, and diagnosis is often delayed and leads to unnecessary treatments (intubation, tracheostomy and high dose steroids).

METHODS

A retrospective study of 15 cases of VCD (8 cases of isolated VCD and 7 cases of VCD with associated asthma) describing the main clinical features and the diagnosis strategy.

RESULTS

Apparent upper airway obstruction, with or without associated asthma, requires an ear nose and throat examination with laryngoscopy to confirm the paradoxical adduction of the vocal cords during an acute episode of dyspnoea or during a provocation test with triggers like exercise or exposure to irritants, and for the purpose of differential diagnosis.

CONCLUSIONS

VCD remains under-appreciated and misdiagnosed, often by mimicking asthma with which it can be associated. A delayed diagnosis by emergency specialists, pulmonologists and ear nose and throat surgeons leads to unnecessary treatments and morbidity before specific therapy can be given.

ERS/ESTS clinical guidelines on fitness for radical therapy in lung cancer patients (surgery and chemo-radiotherapy)

A collaboration of multidisciplinary experts on the functional evaluation of lung cancer patients has been facilitated by the European Respiratory Society (ERS) and the European Society of Thoracic Surgery (ESTS), in order to draw up recommendations and provide clinicians with clear, up-to-date guidelines on fitness for surgery and chemo-radiotherapy. The subject was divided into different topics, which were then assigned to at least two experts. The authors searched the literature according to their own strategies, with no central literature review being performed. The draft reports written by the experts on each topic were reviewed, discussed and voted on by the entire expert panel. The evidence supporting each recommendation was summarised, and graded as described by the Scottish Intercollegiate Guidelines Network Grading Review Group. Clinical practice guidelines were generated and finalized in a functional algorithm for risk stratification of the lung resection candidates, emphasising cardiological evaluation, forced expiratory volume in 1 s, systematic carbon monoxide lung diffusion capacity and exercise testing. Contrary to lung resection, for which the scientific evidences are more robust, we were unable to recommend any specific test, cut-off value, or algorithm before chemo-radiotherapy due to the lack of data. We recommend that lung cancer patients should be managed in specialised settings by multidisciplinary teams.

[Preoperative assessment of lung cancer patients before lung resection]

The aim of the functional evaluation of lung cancer patients before lung resection is to evaluate the risk of peri-operative cardio-respiratory complications. The successive steps of the functional assessment are determined according to the predictive value, the invasiveness, and the sophistication of the tests. The cardiovascular risk is evaluated using clinical predictors and ECG findings. If both are negative, the first step of the respiratory function assessment will be FEV1 measurement. Simultaneous measurement of CO diffusing lung capacity (DLCO), which has a high predictive value of complications, is highly recommended by some authors. The second and the third steps will be either exercise testing or split function studies based on quantitative perfusion scan results, the position of the test in the algorithm depending on the authors. Formal exercise testing has been found to be the best predictor of postoperative complications in several studies. However, it does not evaluate the functional contribution of the parenchyma to be resected, which required a perfusion scan. On the other hand, patients with low values of predicted post-operative FEV1 or DLCO should undergo exercise tests. Eventually, clinical, surgical and anesthetic factors should also be taken into account in addition to the functional evaluation to assess the perioperative risk of the patient.

Relationship Between Very High Physical Activity Energy Expenditure, Heart Rate Variability and Self-Estimate of Health Status in Middle-Aged Individuals

In middle-aged persons, moderate physical activity energy expenditure (PAEE) has been shown to be associated with increased vagal-related heart rate variability (HRV) indexes and better health status. The purpose of this study was to determine whether a very high PAEE has greater effect on vagal-related HRV indexes and self-estimates of well-being in middle-aged subjects having distinct long-term physical activity profiles. Forty-four subjects were divided into three groups on the basis of the sport score of the Modified Baecke Questionnaire for Older Adults: sedentary (SED, n = 15), moderately-trained (MT, n = 16), and highly-trained subjects (HT, n = 13). PAEE was estimated by triaxial accelerometry during one week. Time and frequency domain HRV indexes were determined during quiet periods in the morning on 5-min R-R interval segments under controlled breathing. Quality of life was evaluated using the SF-36 health survey questionnaire. PAEE was significantly different for each group (374.5 +/- 13.8, 616.8 +/- 22.4, and 1086.6 +/- 43.2 kcal . day (-1) for SED, MT, and HT, respectively, p < 0.001). MT presented significantly higher vagal-related HRV indexes than SED and HT (p < 0.05). None of the HRV indexes was significantly greater in HT than in SED. MT and HT had similar health status scores, which were significantly higher than for SED. These results indicate that in middle-aged subjects, habitual moderate PAEE is associated with greater vagal tone and self-estimates of well-being compared to low PAEE. In contrast, very high PAEE is associated with similar vagal-related indexes as low PAEE, despite better overall health status.

Mechanisms of renal hyporesponsiveness to ANP in heart failure

The atrial natriuretic peptide (ANP) plays an important role in chronic heart failure (CHF), delaying the progression of the disease. However, despite high ANP levels, natriuresis falls when CHF progresses from a compensated to a decompensated state, suggesting emergence of renal resistance to ANP. Several mechanisms have been proposed to explain renal hyporesponsiveness, including decreased renal ANP availability, down-regulation of natriuretic peptide receptors and altered ANP intracellular transduction signal. It has been demonstrated that the activity of neutral endopeptidase (NEP) is increased in CHF, and that its inhibition enhances renal cGMP production and renal sodium excretion. In vitro as well as in vivo studies have provided strong evidence of an increased degradation of intracellular cGMP by phosphodiesterase in CHF. In experimental models, ANP-dependent natriuresis is improved by phosphodiesterase inhibitors, which may arise as new therapeutic agents in CHF. Sodium-retaining systems likely contribute to renal hyporesponsiveness to ANP through different mechanisms. Among these systems, the renin-angiotensin-aldosterone system has received particular attention, as angiotensin II and ANP have renal actions at the same sites and inhibition of angiotensin-converting enzyme and angiotensin-receptor blockade improve ANP hyporesponsiveness. Less is known about the interactions between the sympathetic nervous system, endothelin or vasopressin and ANP, which may also blunt ANP-induced natriuresis. To summarize, renal hyporesponsiveness to ANP is probably multifactorial. New treatments designed to restore renal ANP efficiency should limit sodium retention in CHF patients and thus delay the progression to overt heart failure.

Time-courses in renin and blood pressure during sleep in humans

We previously described a strong concordance between nocturnal oscillations in plasma renin activity (PRA) and the rapid eye movement (REM) and non-REM (NREM) sleep cycles, but the mechanisms inducing PRA oscillations remain to be identified. This study was designed to examine whether they are linked to sleep stage-related changes in arterial blood pressure (ABP). Analysis of sleep electroencephalographic (EEG) activity in the delta frequency band, intra-arterial pressure, and PRA measured every 10 min was performed in eight healthy subjects. Simultaneously, the ratio of low frequency power to low frequency power + high frequency power [LF/(LF + HF)] was calculated using spectral analysis of R--R intervals. The cascade of physiological events that led to increased renin release during NREM sleep could be characterized. First, the LF/(LF + HF) ratio significantly (P < 10(-4) decreased, indicating a reduction in sympathetic tone, concomitantly to a significant (P < 10(- 3) decrease in mean arterial pressure (MAP). Delta wave activity increased (P < 10(-4) 10-20 min later and was associated with a lag of 0-10 min with a significant rise in PRA (P < 10(-4) . Rapid eye movement sleep was characterized by a significant increase (P < 10(-4) in the LF/(LF + HF) ratio and a decrease (P < 10(-4) in delta wave activity and PRA, whereas MAP levels were highly variable. Overnight cross-correlation analysis revealed that MAP was inversely correlated with delta wave activity and with PRA (P < 0.01 in all subjects but one). These results suggest that pressure-dependent mechanisms elicit the nocturnal PRA oscillations rather than common central processes controlling both the generation of slow waves and the release of renin from the kidney.

Non-invasive cardiac output evaluation during a maximal progressive exercise test, using a new impedance cardiograph device

One of the greatest challenges in exercise physiology is to develop a valid, reliable, non-invasive and affordable measurement of cardiac output (CO). The purpose of this study was to evaluate the reproducibility and accuracy of a new impedance cardiograph device, the Physio Flow, during a 1-min step incremental exercise test from rest to maximal peak effort. A group of 12 subjects was evaluated to determine the reproducibility of the method as follows: (1) each subject performed two comparable tests while their CO was measured by impedance cardiography using the new device (COImp1, COImp2), and (2) in a subgroup of 7 subjects CO was also determined by the direct Fick method (COFick) during the second test. The mean difference between the values obtained by impedance (i.e. COImp1-COImp2) was -0.009 l.min-1 (95% confidence interval: -4.2 l.min-1, 4.2 l.min-1), and CO ranged from 3.55 l.min-1 to 26.75 l.min-1 (n = 146). When expressed as a percentage, the difference (COImp1-COImp2) did not vary with increasing CO. The correlation coefficient between the values of COImp and COFick obtained during the second exercise test was r = 0.94 (P < 0.01, n = 50). The mean difference expressed as percentage was -2.78% (95% confidence interval: -27.44%, 21.78%). We conclude that COImp provides a clinically acceptable evaluation of CO in healthy subjects during an incremental exercise.

Sleep deprivation blunts the night time increase in aldosterone release in humans

The aim of this study was to determine the effect of sleep deprivation on the 24-h profile of aldosterone and its consequences on renal function. Aldosterone and its main hormonal regulatory factors, ACTH (evaluated by cortisol measurement) and the renin-angiotensin system [RAS, evaluated by plasma renin activity (PRA) measurement] were determined every 10 min for 24 h in eight healthy subjects in the supine position, once with nocturnal sleep and once during total 24-h sleep deprivation. Plasma Na(+) and K(+) were measured every 10 min in four of these subjects. In an additional group of 13 subjects under enteral nutrition, diuresis, natriuresis and kaliuresis were measured once during the sleep period (23.00--07.00 h) and once during a 23.00--07.00 hours sleep deprivation period. During sleep deprivation, aldosterone displayed lower plasma levels and pulse amplitude in the 23.00--07.00-hour period than during sleep. Similarly, PRA showed reduced levels and lower pulse frequency and amplitude. Plasma cortisol levels were slightly enhanced during sleep deprivation. Overnight profiles of plasma K(+) and Na(+) were not affected. Diuresis and kaliuresis were not influenced by sleep deprivation. In contrast, natriuresis significantly increased during sleep deprivation. This study demonstrates that sleep deprivation modifies the 24-h aldosterone profile by preventing the nocturnal increase in aldosterone release and leads to altered overnight hydromineral balance.

Exercise training with a heart device: a hemodynamic, metabolic, and hormonal study

PURPOSE

The mechanisms of the training-induced improvements in left ventricular assist (LVAD) patients are unknown.

METHODS

We measured the hemodynamic, gas exchange, and metabolic and hormonal effects of 6-wk exercise training in a cardiogenic shock patient who was assisted by an LVAD.

RESULTS

After training, the peak power and VO2 increased by 166% and 56%, respectively (80 W and 16.1 mL x min(-1) x kg(-1)), whereas the ventilatory drive decreased. Although the LVAD output increased little with exercise, the systemic cardiac output rose (adequately for the VO2) from 5.91 and 4.90 L x min(-1) at rest to 9.75 and 9.47 L x min(-1) at peak work rate, before and after training, respectively. Thus, the left ventricle ejected again through the aortic valve. Unloading and/or retraining resulted in a left ventricular filling pressure decrease. Although the right ventricular ejection fraction increased with exercise, it decreased again at the maximal load after training. For a given work rate the arterial lactate, the norepinephrine (NE) and epinephrine (E) concentrations fell after training, but the enhanced maximal work rate elicited higher NE and E concentrations (4396 and 1848 pg x mL(-1), respectively). The lack of right ventricular unloading might have kept the atrial natriuretic peptide higher after training, but the blood cyclic GMP and endothelin were lower after training.

CONCLUSION

In an LVAD patient, retraining returns the exercise capacity to the class III level by peripheral and left ventricular hemodynamic improvements, but the safety of maximal exercise remains to be proven in terms of right ventricular function and orthosympathetic drive.

Ultradian rhythms in hydromineral hormones

The maintenance of hydromineral homeostasis depends on the coordinated action of arginine vasopressin (AVP), atrial natriuretic peptide (ANP), the renin-angiotensin-aldosterone system and other recently identified endocrine or paracrine hormones. Several reports have pointed out the changes in urinary excretion and osmolality during the sleep-wake cycle and the rapid eye movement (REM)-non(N)REM sleep cycles. No such changes occur for ANP levels which have a flat profile over 24 h. The pulsatile fluctuations of AVP are described as random. The ultradian rhythm of plasma renin activity (PRA) depends on the regularity of the REM-NREM sleep cycles and the nocturnal curves reflect all disturbances in the internal sleep structure. A study with a shift in the normal sleep time clearly demonstrated that both PRA and aldosterone oscillations are sleep-stage dependent. These hormones could account for the ultradian variations in renal function. The nocturnal oscillations in sympathovagal balance may play an additional role. It is suggested that a central generator synchronizes endocrine, renal, autonomic and sleep processes.

Exercise-induced increase in circulating adrenomedullin is related to mean blood pressure in heart transplant recipients

Adrenomedullin (ADM) is a newly discovered potent vasorelaxing and natriuretic peptide that recently has been shown to be increased after heart transplantation. To investigate the hemodynamic factors modulating its release and the eventual role of ADM in blood pressure regulation after heart transplantation, seven matched heart-transplant recipients (Htx) and seven normal subjects performed a maximal bicycle exercise test while monitoring for heart rate, blood pressure, and circulating ADM. Baseline heart rate and systemic blood pressure were higher in Htx; left ventricular mass index and ADM tended to be higher after heart transplantation and correlated positively in Htx (r = 0.79, P = 0.03). As expected, exercise-induced increase in heart rate was lower in Htx than in controls (60 +/- 11 % vs. 121 +/- 14 %, respectively) and blood pressure increase was similar in both groups. Maximal exercise increased significantly plasma ADM in both groups (from 25.3 +/- 3.1 to 30.7 +/- 3.5 pmol/L, P < 0.05 and from 15.2 +/- 1.4 to 29.1 +/- 4.4 pmol/L, P = 0.02 in Htx and controls, respectively), the hypotensive peptide level remaining elevated until the 30th min of recovery. A significant inverse relationship was observed between peak mean blood pressure and circulating ADM in Htx (r = -0.86, P < 0.02). Besides showing that circulating ADM is increased after heart transplantation, the present study demonstrates a positive relationship between baseline ADM and left ventricular mass index. Furthermore, maximal exercise-induced increase in ADM is inversely related to mean blood pressure in Htx, suggesting that ADM might participate in blood pressure regulation during exercise after heart transplantation.

A new impedance cardiograph device for the non-invasive evaluation of cardiac output at rest and during exercise: comparison with the "direct" Fick method

The objectives of this study were to evaluate the reliability and accuracy of a new impedance cardiograph device, the Physio Flow, at rest and during a steady-state dynamic leg exercise (work intensity ranging from 10 to 50 W) performed in the supine position. We compared cardiac output determined simultaneously by two methods, the Physio Flow (QcPF) and the direct Fick (QcFick) methods. Forty patients referred for right cardiac catheterisation, 14 with sleep apnoea syndrome and 26 with chronic obstructive pulmonary disease, took part in this study. The subjects' oxygen consumption values ranged from 0.14 to 1.19 l x min(-1). The mean difference between the two methods (QcFick - QcPF) was 0.04 l x min(-1) at rest and 0.29 l x min(-1) during exercise. The limits of agreement, defined as mean difference +/- 2SD, were -1.34, +1.41 l x min(-1)] at rest and -2.34, +2.92 l x min(-1) during exercise. The difference between the two methods exceeded 20% in only 2.5% of the cases at rest, and 9.3% of the cases during exercise. Thoracic hyperinflation did not alter QcPF. We conclude that the Physio Flow provides a clinically acceptable and non-invasive evaluation of cardiac output under these conditions. This new impedance cardiograph device deserves further study using other populations and situations.

Lack of acute cyclosporine nephrotoxicity in late heart-transplant recipients

BACKGROUND

Cyclosporine induces daily renal hypoperfusion in subjects with normal atrial natriuretic peptide (ANP) levels, but its acute effects in heart transplant patients with increased ANP remain to be determined.

METHODS

Cyclosporinemia and creatinine clearance were monitored during 7 hours following cyclosporine administration in 6 heart transplant patients.

RESULTS

CONCLUSIONS

No acute cyclosporine-induced decrease in creatinine clearance was observed after heart transplantation. These data suggest that maintenance cyclosporine dose may be less nephrotoxic than suspected and that increased ANP might protect the renal function late after heart transplantation.

VO(2) kinetics reveal a central limitation at the onset of subthreshold exercise in heart transplant recipients

Because the cardiocirculatory response of heart transplant recipients (HTR) to exercise is delayed, we hypothesized that their O(2) uptake (VO(2)) kinetics at the onset of subthreshold exercise are slowed because of an impaired early "cardiodynamic" phase 1, rather than an abnormal subsequent "metabolic" phase 2. Thus we compared the VO(2) kinetics in 10 HTR submitted to six identical 10-min square-wave exercises set at 75% (36 +/- 5 W) of the load at their ventilatory threshold (VT) to those of 10 controls (C) similarly exercising at the same absolute (40 W; C40W group) and relative load (67 +/- 14 W; C67W group). Time-averaged heart rate, breath-by-breath VO(2), and O(2) pulse (O(2)p) data yielded monoexponential time constants of the VO(2) (s) and O(2)p increase. Separating phase 1 and 2 data permitted assessment of the phase 1 duration and phase 2 VO(2) time constant (). The VO(2) time constant was higher in HTR (38.4 +/- 7.5) than in C40W (22.9 +/- 9.6; P < or = 0. 002) or C67W (30.8 +/- 8.2; P < or = 0.05), as was the O(2)p time constant, resulting from a lower phase 1 VO(2) increase (287 +/- 59 vs. 349 +/- 66 ml/min; P < or = 0.05), O(2)p increase (2.8 +/- 0.6 vs. 3.6 +/- 1.0 ml/beat; P < or = 0.0001), and a longer phase 1 duration (36.7 +/- 12.3 vs. 26.8 +/- 6.0 s; P < or = 0.05), whereas the was similar in HTR and C (31.4 +/- 9.6 vs. 29.9 +/- 5.6 s; P = 0.85). Thus the HTR have slower subthreshold VO(2) kinetics due to an abnormal phase 1, suggesting that the heart is unable to increase its output abruptly when exercise begins. We expected a faster in HTR because of their prolonged phase 1 duration. Because this was not the case, their muscular metabolism may also be impaired at the onset of subthreshold exercise.

Interrupter technique versus plethysmography for measurement of respiratory resistance in children with asthma or cystic fibrosis

The purpose of the present study was to compare measurements of respiratory system resistance by the interrupter method (Rrsint) with those of airway resistance by plethysmography (Raw) in nonobstructed children with asthma or cystic fibrosis (ratio of forced expiratory volume in 1 sec to vital capacity, FEV(1)/VC >/=80% with a forced expiratory flow rate between 25-75% of forced vital capacity, FEF(25-75) >/=75% of normal values) and in obstructed children with the same diseases (FEV(1)/VC <80% and/or FEF(25-75) <75% of normal values). Eighty-one children (47 asthmatics and 34 suffering from cystic fibrosis) aged 5-18 years (mean 11.2 +/- SD 3.4 years) were included in the study. For the overall group, we observed generally lower values for Raw (4.7 +/- 2. 8 cmH(2)O.L(-).s) than for Rrsint20 (extrapolation of the mouth pressure during occlusion to 40 ms after interruption) (5.6 +/- 1.7 cmH(2)O.L(-1).s) (P < 0.02), or for Rrsint40 (extrapolation of the mouth pressure during occlusion to 60 ms after interruption) (6.6 +/- 2.2 cmH(2)O.L(-1).s) (P < 0.001), but there was no difference between Rrsint20 and Raw in the obstructed subgroup. Moreover, we observed a correlation between the difference (Rrsint20 - Raw) expressed in percentage of predicted values and the degree of obstruction estimated by FEV(1)/VC (r = 0.56, P < 0.001). The differences between the specific resistances (sRrsint20 - sRaw, sRrsint40 - sRaw) were also correlated with the severity of the obstruction (r = 0.65, P < 0.001 and r = 0.57, P < 0.001, respectively). We observed also that the tendency to underestimate resistance by Rrsint in obstructed children was not the same in children with asthma and cystic fibrosis. We conclude that the tendency of Rrsint, as measured with our method, to underestimate airway obstruction appears to increase in proportion to the severity of the airway obstruction.

[Do patients with squamous cell carcinoma or adenocarcinoma of the lung have different smoking histories?]

Adenocarcinoma of the lung is now the most frequent histological subtype of lung cancer in North America. The increase in cases of adenocarcinoma of the lung has begun since the seventies and has been attributed to the changes in smoking habits and to the rise of lung cancer incidence in females who preferentially develop adenocarcinoma. In France, squamous cell carcinoma of the lung still predominates, but a recent increase in adenocarcinoma has been observed. We performed a comparative study of the smoking habits of patients referred to the chest diseases or to the thoracic surgery departments of the University Hospital of Strasbourg for either a squamous cell carcinoma or an adenocarcinoma, between march 1st, 1995 and april 30th, 1998. The statistical analysis, based on conditional logistic regression, was performed after matching one adenocarcinoma with one squamous cell carcinoma. The matching factors were age, gender and the date of diagnosis. Patients with adenocarcinoma were significantly younger when they started smoking and when they quitted smoking. In these patients, there was also a trend towards a more frequent deep inhalation and use of filter cigarettes. On the other hand, patients with a squamous cell carcinoma smoked more frequently hand-rolled cigarettes. There was no difference with respect to environmental tobacco smoke exposure.

Lung membrane diffusing capacity, heart failure, and heart transplantation

The pulmonary diffusing capacity for carbon monoxide (DLCO) is reduced in chronic heart failure and remains decreased after heart transplantation. This decrease in DLCO may depend on a permanent alteration after transplantation of one or the other of its components: diffusion of the alveolar capillary membrane or the pulmonary capillary blood volume (Vc). Therefore, we measured DLCO, the membrane conductance, and Vc before and after heart transplantation. At the time of hemodynamic measurements, the Roughton and Forster method of measuring DLCO at varying alveolar oxygen concentrations was used to determine the membrane conductance, Vc, DLCO/alveolar volume (VA), the membrane conductance/VA and thetaVc/VA (theta = carbon monoxide conductance of blood, VA = alveolar volume) in 21 patients with class III to IV heart failure before and after transplantation, and in 21 healthy controls. Transplantation normalized pulmonary capillary pressure and increased cardiac index. DLCO was decreased before transplantation (7.11 vs 10.0 mmol/min/kPa in controls), but DLCO/VA was normal (1.67+/-0.44 vs 1.71+/-0.26 mmol/min/kPa/L in controls). DLCO/VA remained unchanged after transplantation, because the decrease in Vc (82+/-30 vs 65+/-18 ml before and after transplantation) and thetaVc/VA was not compensated by the changes in membrane conductance (11+/-4 vs 12+/-5 mmol/min/kPa before and after transplantation, respectively) and membrane conductance/VA. We conclude that the decrease in DLCO in patients with chronic heart failure is due to a restrictive ventilatory pattern because their DLCO/VA remains normal; the decrease in the membrane conductance is compensated by the increase in Vc. After transplantation, the decrease in Vc due to normalization of pulmonary hemodynamics is not completely compensated for by an increase in membrane conductance. Because the membrane conductances, measured before and after transplantation, are negatively correlated with duration of heart failure, its abnormal pulmonary hemodynamics may have irreversibly altered the alveolar capillary membrane.

Aldosterone release during the sleep-wake cycle in humans

The aim of this study was to assess the relative influence on the 24-h aldosterone profile of the adrenocorticotropic system, primarily modulated by a circadian rhythmicity, and the renin-angiotensin system, which is influenced by sleep. Cortisol, plasma renin activity (PRA), and aldosterone were measured for 24 h in healthy subjects under basal conditions, once with nocturnal sleep and once with a night of sleep deprivation followed by 8 h of daytime sleep. The sleep period displayed high mean aldosterone levels, pulse amplitude, and frequency that were reduced during waking periods. During sleep, aldosterone pulses were mainly related to PRA oscillations, whereas they were mainly associated with cortisol pulses during waking periods. Cross-correlation analysis between sleep electroencephalographic activity in the delta band and aldosterone levels yielded significant results, aldosterone following delta waves by approximately 30 min. This study demonstrates that the 24-h aldosterone profile is strongly influenced by sleep processes. A dual influence, by the renin-angiotensin system during sleep and by the adrenocorticotropic system during wakefulness, is exerted on aldosterone pulses throughout the 24-h period.

Enhanced brain natriuretic peptide response to peak exercise in heart transplant recipients

We investigated the atrial (ANP) and brain natriuretic peptides (BNP), catecholamines, heart rate, and blood pressure responses to graded upright maximal cycling exercise of eight matched healthy subjects and cardiac-denervated heart transplant recipients (HTR). Baseline heart rate and diastolic blood pressure, together with ANP (15.2 +/- 3.7 vs. 4.4 +/- 0.8 pmol/l; P < 0.01) and BNP (14.3 +/- 2. 6 vs. 7.4 +/- 0.6 pmol/l; P < 0.01), were elevated in HTR, but catecholamine levels were similar in both groups. Peak exercise O2 uptake and heart rate were lower in HTR. Exercise-induced maximal ANP increase was similar in both groups (167 +/- 34 vs. 216 +/- 47%). Enhanced BNP increase was significant only in HTR (37 +/- 8 vs. 16 +/- 8%; P < 0.05). Similar norepinephrine but lower peak epinephrine levels were observed in HTR. ANP and heart rate changes from rest to 75% peak exercise were negatively correlated (r = -0.76, P < 0.05), and BNP increase was correlated with left ventricular mass index (r = 0.83, P < 0.01) after heart transplantation. Although ANP increase was not exaggerated, these data support the idea that the chronotropic limitation secondary to sinus node denervation might stimulate ANP release during early exercise in HTR. Furthermore, the BNP response to maximal exercise, which is related to the left ventricular mass index of HTR, is enhanced after heart transplantation.

Normal short-term renal response to acute volume expansion in heart transplant recipients: a role for atrial natriuretic peptide?

BACKGROUND

The breakdown of blood pressure and body fluid homeostasis observed in heart transplant (Htx) recipients may partly be due, as in heart failure, to a blunted renal response to elevated atrial natriuretic peptide (ANP).

METHOD

This possibility was addressed through determination of the relationship between ANP, the urinary cyclic guanosine monophosphate (cGMP), a biologic marker of ANP renal activity, and the early renal responses to 10 mL/kg isotonic saline infusion over 30 minutes in 8 control subjects and 8 matched Htx recipients.

RESULTS

Urine flow, natriuresis, and urinary cGMP excretion increased similarly in both groups, resulting in elimination of, respectively, 1/2 and 2/3 of the sodium and the water load during the experiment that lasted 4 hours and 30 minutes. Plasma renin and aldosterone decreases were similar in both groups. Elevated ANP further increased in Htx after saline infusion (from 19.5 +/- 3.7 to 33.8 +/- 5.6 pmol/L, P < .001). Plasma cGMP paralleled ANP in both groups (r = 0.81; P < .001). Significant correlations were observed between plasma ANP and urinary cGMP excretion (r = 0.48, P < .025 and r = 0.43, P < .05 in Htx recipients and control subjects) and between plasma ANP and urinary sodium excretion (r = 0.64, P < .001 in Htx recipients).

CONCLUSION

In spite of a relative renal hyporesponsiveness to the cardiac hormone, with higher plasma ANP being not associated with increased renal excretions in Htx recipients, ANP is likely to participate in the appropriate short-term renal response to acute volume expansion in Htx recipients.

Dynamic heart rate variability: a tool for exploring sympathovagal balance continuously during sleep in men

We have recently demonstrated that the overnight profiles of cardiac interbeat autocorrelation coefficient of R-R intervals (rRR) calculated at 1-min intervals are related to the changes in sleep electroencephalographic (EEG) mean frequency, which reflect depth of sleep. Other quantitative measures of the Poincaré plots, i.e., the standard deviation of normal R-R intervals (SDNN) and the root mean square difference among successive R-R normal intervals (RMSSD), are commonly used to evaluate heart rate variability. The present study was designed to compare the nocturnal profiles of rRR, SDNN, and RMSSD with the R-R spectral power components: high-frequency (HF) power, reflecting parasympathetic activity; low-frequency (LF) power, reflecting a predominance of sympathetic activity with a parasympathetic component; and the LF-to-HF ratio (LF/HF), regarded as an index of sympathovagal balance. rRR, SDNN, RMSSD, and the spectral power components were calculated every 5 min during sleep in 15 healthy subjects. The overnight profiles of rRR and LF/HF showed coordinate variations with highly significant correlation coefficients (P < 0.001 in all subjects). SDNN correlated with LF power (P < 0.001), and RMSSD correlated with HF power (P < 0.001). The overnight profiles of rRR and EEG mean frequency were found to be closely related with highly cross-correlated coefficients (P < 0. 001). SDNN and EEG mean frequency were also highly cross correlated (P < 0.001 in all subjects but 1). No systematic relationship was found between RMSSD and EEG mean frequency. In conclusion, rRR appears to be a new tool for evaluating the dynamic beat-to-beat interval behavior and the sympathovagal balance continuously during sleep. This nonlinear method may provide new insight into autonomic disorders.

Skeletal muscle response to short endurance training in heart transplant recipients

OBJECTIVES

We sought to examine the effects of endurance training on the ultrastructural characteristics of skeletal muscle in heart transplant recipients (HTRs) and age-matched control subjects (C).

BACKGROUND

Deconditioning is one of the factors involved in the peripheral limitation of exercise capacity of HTRs, and training has proven to be beneficial.

METHODS

Biopsies of the vastus lateralis muscle, analyzed by ultrastructural morphometry, and quadriceps muscle cross-sectional area, assessed by computed tomography (CT), were performed in 12 HTRs and 7 age-matched C before and 6 weeks after an endurance training program. Maximal oxygen uptake (peak VO2) was determined by an incremental exercise test. Additionally muscle biopsies were performed before and after a 6-week control period in four HTRs to check for spontaneous improvement.

RESULTS

Training resulted in similar increases in peak VO2 (11% in HTRs, 8.5% in C), ventilatory threshold (23% in HTRs, 32% in C) and total endurance work (54% in HTRs, 31% in C). Volume density of total mitochondria increased significantly (26% in HTRs, 33% in C) with a predominant increase of subsarcolemmal mitochondrial volume density (74% in HTRs, 70% in C). The capillary/fiber ratio increased by 19% in C only. In the nontrained group, none of the structural markers was spontaneously modified.

CONCLUSIONS

Six weeks of endurance training in HTRs and C led to similar improvements of aerobic work capacity. However, the decreased muscular capillary network in HTRs remained unchanged with training. Immunosuppressive therapy might be responsible for the discrepancy between the normal mitochondrial content and the reduced capillary supply of these patients.

Oscillations in sympatho-vagal balance oppose variations in delta-wave activity and the associated renin release

To determine the potential role of the sympathetic nervous system in the generation of the oscillations in PRA over the 24-h period, we used the autocorrelation coefficient of RR interval (rRR), a new tool to evaluate the sympatho-vagal balance continuously. We determined the influence of the sympathetic nervous system both on the nocturnal PRA oscillations associated to increases in delta-wave activity and on the daytime oscillations that occur randomly in awake subjects. PRA and rRR were determined every 10 min during 24 h in nine healthy subjects under continuous bed rest. Electroencephalographic spectral analysis was used to establish the variations in delta-wave activity during sleep, from 2300-0700 h. The overnight profiles in PRA, rRR and delta-wave activity were analyzed using a modified version of the pulse detection program ULTRA. The temporal link among the profiles of rRR, PRA, and delta-wave activity was quantified using cross-correlation analysis. During sleep, large oscillations in PRA were strongly linked to variations in delta-wave activity. They were preceded by opposite oscillations in rRR, decreases in rRR reflecting predominant vagal activity, and increases in rRR reflecting sympathetic dominance. During the waking periods, the levels of rRR were higher, with smaller variations. The daytime PRA oscillations were not associated with any significant changes in rRR, and conversely, significant oscillations in rRR were not followed by any significant changes in PRA. In conclusion, the sympathetic nervous system is not directly involved in the generation of renin oscillations observed under basal conditions. During sleep, the oscillations in sympatho-vagal balance are inversely related to the variations in delta-wave activity and the associated renin release. The processes that give the intermittent signal for concomitant increases in slow wave activity and renin release from the kidney remain to be identified.

Prognostic value of histology in patients with non-small cell lung cancer

To evaluate the impact of non-small cell lung cancer (NSCLC) histological subtypes on survival, we performed a retrospective multivariate analysis of survival in 361 patients with a NSCLC diagnosed in 1987 and 1988 at the University Hospital in Strasbourg, France. There were 262 (73%) squamous cell carcinomas (SQ), 59 (16%) adenocarcinomas other than bronchioloalveolar carcinoma (ADOBAC), 24 (7%) bronchioloalveolar carcinoma (BAC) and 16 (4%) large cell carcinomas (LC). The proportion of metastatic disease was significantly higher in the ADOBAC group than in the SQ group (30% vs. 15%, P < 0.001). In operated patients, only extent of disease and age were independent prognostic factors. In patients with unresectable NSCLC, extent of disease had also the heaviest impact on survival. However, in these unresected patients, ADOBAC had a pejorative impact on survival, in contrast to BAC which was of better prognosis. If these results are confirmed by prospective studies, this will support stratification according to histological subtypes in clinical trials involving inoperable NSCLC patients.

A phase II trial of radiochemotherapy with daily carboplatin, after induction chemotherapy (carboplatin and etoposide), in locally advanced nonsmall-cell lung cancer: final analysis

PURPOSE

To evaluate feasibility and efficacy of concomitant radiochemotherapy (CRCT) in Stage IIIB nonsmall-cell lung cancer (NSCLC), two induction chemotherapy cycles combining etoposide and carboplatin were first delivered, followed by CRCT with daily radiation fraction in association with carboplatin.

METHODS AND MATERIALS

Forty patients with biopsy-proven, locally advanced unresectable nonmetastatic NSCLC were enrolled. Induction chemotherapy consisted of two cycles (day 1 and day 28) of etoposide (VP16:100 mg/m2, days 1 to 3) and carboplatin (CBDCA:350 mg/m2, day 1). Irradiation starting at day 56, delivered 66 Gy in 2 Gy daily fraction, 5 days a week, along with a daily dose of CBDCA (15 mg/m2) given intravenously 2 to 4 h before radiation. In nonprogressive patients under induction chemotherapy, two additional cycles of VP16-CBDCA were administered 4 weeks after the completion of CRCT.

RESULTS

Out of the 40 patients enrolled (38 males, 2 females), 37 (93%) received induction chemotherapy as scheduled, with 38% Grade 3-4 hematological toxicity. Response rate to induction chemotherapy was 11% (4/37). No tumor became resectable. CRCT was delivered to 32 of these 37 patients, with full doses given to 91% of them. Clinical and hematological Grade 3-4 toxicity rates were 21 and 13%, respectively. Additional chemotherapy was delivered in 12 of 26 nonprogressive patients. At final evaluation, performed 3 months after the end of CRCT, 38% of 26 evaluable patients were responders (4 complete and 6 partial), leading to a 25% (10 of 40) overall objective response rate. Of these 10 responders, 8 became responders after CRCT only. Overall, the 1-year local control rate was 28% (11 of 40). The median survival time was 9 months and the 1-year and 2-year overall survival rates were 38 and 15%, respectively. Thirty-six patients died from local progression (25 patients), distant metastasis (9 patients), or pulmonary fibrosis (2 patients).

CONCLUSION

Concomitant CRCT with CBDCA is feasible with acceptable induction chemotherapy-related toxicity and a 1-year local control rate of 28%. Response rate to induction chemotherapy was low and better chemotherapy combination should be used to reduce distant failure probability and to improve local response rate before CRCT.

International differences in epidemiology of lung adenocarcinoma

In Europe, the squamous cell carcinoma is the most frequent non-small cell lung cancer (NSCLC) subtype and until now, no increase in incidence of lung adenocarcinoma (ADC) has been described (except in the Netherlands), in contrast to North America where ADC predominates. Our aim was to compare the percentage of ADC in Montreal (MTL), Canada, with that in Strasbourg (STBG), France. We prospectively identified patients with NSCLC in MTL and in STBG over an 8-month period and described the distribution of NSCLC by sex, age, subtype and smoking history. A total of 172 patients in MTL and 166 in STBG were identified. The male/female ratio was significantly different in STBG (12:1) and in MTL (2:1). The percentage of ADC was significantly higher in MTL (40%) than in STBG (30%). This difference is partly due to the higher number of women with NSCLC in Montreal combined with the predominance of ADC in women. The proportion of ADC decreased with age in STBG, but was similar in each age category in MTL. In STBG, most women with NSCLC had never smoked (69%), in contrast to MTL where only 16% of women had never smoked. In conclusion, ADC is more frequent in MTL than in STBG. This is partly due to the higher number of women with NSCLC in MTL combined with the predominance of ADC in women. The greatest proportion of ADC subtype in the youngest cohorts of men in STBG suggests that ADC may be on the rise in this city.

The increasing incidence of lung adenocarcinoma: reality or artefact? A review of the epidemiology of lung adenocarcinoma

Lung adenocarcinoma is the most common cell type in females (smokers or non-smokers) and in non-smoking males. Its incidence has been increasing in younger cohorts of males and females until very recent years. Changes in classification and in pathological techniques account for some of this increase. In females and non-smoker males, the increase could be partly due to a detection bias in former studies. Nevertheless, successive cohorts over time seem more likely to develop adenocarcinoma and less likely to develop squamous cell carcinoma. These differences between birth cohorts suggest that the increasing incidence of adenocarcinoma is not only due to changes in pathological diagnosis. Geographical differences are also observed: in Europe, the squamous cell type still predominates and an increase in incidence of adenocarcinoma has only been reported in the Netherlands. In Asia, in the 1960s and 1970s, the proportion of adenocarcinoma was higher than in North America or Europe and seems to be increasing. To what extent these differences are due to differences. In establishing diagnosis remains unknown. Despite these biases in temporal and geographical trends detailed in this review, there has probably been a true increase in incidence of adenocarcinoma. An explanation for this should be sought in studies on detailed smoking history and passive smoking exposure, occupational exposure, diet and cooking, pollution and other environmental factors.

Moderate endurance training has no effect on the parathyroid function of heart transplant patients

The benefit of retraining for heart transplant recipients (HTR) is now well established. The rehabilitation of these patients can be compromised by osteopenia and bone fractures. The resting levels of parathyroid hormone (PTH) and exercise-induced increases are higher in HTR than in healthy controls. To evaluate the effect of a moderate endurance training programme on parathyroid activity, six HTR, an average of 18 months after transplant, and seven healthy sedentary controls have been studied. None of the subjects had a history of bone disease. Two exercise tests (square wave endurance exercise tests, SWEET) with identical work rates were performed before and after training. Intact PTH, ionized calcium (Ca2+), phosphorus (Pi) and pH were measured at rest, during exercise and in the recovery periods. Training consisted of a 45-min SWEET three times a week for 6 weeks. Levels of Ca2+, Pi and PTH showed a significant increase during the exercise session in both groups. Ca2+ and Pi levels decreased rapidly after the cessation of exercise whereas PTH reached a peak at the 10th min of the recovery in both groups. This increase in PTH was significantly higher in HTR than in controls. However, despite a significant improvement of total endurance work (+ 28% in HTR, +29% in controls) this endurance training had no effect on resting levels of PTH, plasma Ca2+ or Pi, nor on their exercise-induced variations. The exercise-induced decrease in pH was less pronounced after training which is evidence of training. We conclude that a short endurance training programme does not alter the moderate hyperparathyroidism of HTR. The effect of such a training programme on bone mass and bone mineral density needs now to be evaluated.

The concept of Raynaud's phenomenon of the lung revisited

PURPOSE

Having observed that a cold pressor test (CPT) induces a decrease in carbon monoxide single breath diffusing capacity (DLco) in normal subjects contrary to the findings of Fahey et al (Am J Med. 1984; 76:263-269), we compared the response to CPT for the two types of Raynaud's phenomenon.

PATIENTS

Two groups of 8 patients suffering from primary or secondary Raynaud's phenomenon were examined.

METHODS

Single breath diffusing capacity, mean pulmonary artery pressure (PAP), cardiac output (CO), pulmonary capillary wedge pressure (PwP), and pulmonary vascular resistance (PVR) were measured before and 30 minutes after CPT, which consisted of immersing both hands in a water bath at 12 degrees C for 2 minutes.

RESULTS

Cold pressor testing induced no change in DLco or cardiovascular parameters in patients with secondary Raynaud's phenomenon. Conversely, in patients with the primary form, it induced a significant decrease in DLco (16%), PAP (20%), and PVR (27%), whereas CO and PwP remained unaltered.

CONCLUSIONS

The concept of pulmonary Raynaud's phenomenon had to be reconsidered, as it is also observed in normal subjects, and is due to a vasodilatation and not to a vasoconstriction of the pulmonary artery (Frans et al, J Appl Physiol. 1994; 76:750-755). In patients with primary Raynaud's phenomenon, the decrease in DLco is not only a physiological response, but a pathological response to a CPT, as it is significantly more marked in patients than in control subjects (16% versus 10% for controls, same reference). The contribution by Fahey et al remains important, however, in that it allows assessing whether a patient with Raynaud's phenomenon suffers from the primary or secondary form of the disease.

Structure of skeletal muscle in heart transplant recipients

OBJECTIVES

This study sought to define the ultrastructural characteristics of skeletal muscle in heart transplant recipients (HTRs) in relation to exercise capacity compared with that in age-matched control subjects.

BACKGROUND

Muscle structural features seem to play an important role in the limitation of exercise capacity of HTRs long after transplantation.

METHODS

The structure of the vastus lateralis muscle was analyzed by ultrastructural morphometry in 16 HTRs and 20 healthy control subjects. Maximal oxygen consumption (peak Vo2) was determined by an incremental exercise test.

RESULTS

Peak Vo2 was significantly lower (by 35%) in HTRs. Fiber size, volume density of mitochondria and intramyocellular lipid deposits were not significantly different between HTRs and control subjects. In contrast, the capillary density and the capillary/fiber ratio were both significantly reduced in HTRs (by 24% and 27%, respectively).

CONCLUSIONS

A normal volume density of mitochondria and a reduced capillary network are the main characteristics of muscle ultrastructure in HTRs by 10 months after transplantation. The muscle structural abnormalities and reduced exercise capacity might be related to immunosuppressive therapy with cyclosporine and corticosteroids as well as deconditioning.

[Passive smoking and bronchial cancer: a difficult relation to establish]

There is a certain controversy over whether there is a relationship between passive smoking and bronchogenic cancer. The first epidemiology studies has found a small increase in the relative risk. Experimental work in animals have demonstrated that the smoke produced by a burning cigarette contains more cancerogenic agents than the smoke inhaled by a smoker. In man where only epidemiology studies are possible, the problem lies in quantifying exposure to passive smoking. Questionnaires or assay of markers such as CO and HbCO, thiocyanates, nicotine and its metabolite cotinine and certain adduits have been used. There are many possibilities for bias in such studies including classification of smokers among non-smokers, confounding factors (age, profession, eating habits), subjects' memory, and data collection errors. Meta-analyses have attempted to overcome the lack of power in many studies. Some of these meta-analyses have used correction factors to take into account publication bias. Meta-analyses have led to the conclusion that the risk for women exposed to their husband's tobacco smoke is somewhat increased compared with a non-smoking non-exposed population. The relative risk is about 2-fold higher and has been observed in Greece. The existence of a dose-intensity relationship has not been confirmed. Likewise, it is impossible to conclude concerning the role of passive smoking in children due to the small amount of data available.

Early alternating chemotherapy and radiotherapy schedule in limited disease stage small cell lung cancer

44 patients with limited small cell lung cancer were treated with six cycles of chemotherapy (cisplatinum 60 mg/m2 day 1, doxorubicin 40 mg/m2 day 1, etoposide 100 mg/m2 days 1-3) alternating with three courses of mediastinal irradiation, the first one starting 7 days after the first day of chemotherapy. A total dose of 55 Gy was delivered. Prophylactic cranial irradiation (30 Gy after the third cycle of chemotherapy) was left to the physician's discretion. 4 patients had radical surgery before combined modality treatment. 29 patients finished the scheduled program. The complete response rate (bronchoscopically confirmed) was 25.6% after two cycles of chemotherapy and 41% at the end of treatment. Median survival time was 17.2 months, with an estimated survival of 32% at 2 years. Main toxicity was haematological with one early toxic death and six premature interruptions of treatment. We conclude that this treatment modality is feasible and efficacious. Prospective studies comparing chemotherapy with alternating or concurrent early radiotherapy schedules in limited disease small cell lung cancer are needed to determine the best treatment modality.

[Monoclonal antibodies and bronchial cancer]

Techniques of production of monoclonal antibodies (MoAb) have provided powerful tools to study biological lung cancer behavior. Immunochemistry is more sensitive than conventional light microscopy examination to detect tumour cells in sputum or pleural effusion, or small cell lung cancer metastases in bone marrow. Immunochemistry is also helpful for the differential diagnosis of carcinoma versus lymphoma or sarcoma, using antibodies directed against antigens such as cytokeratins, vimentin, EMA, LCA, SP100, CEA. In lung cancer, immunochemistry may detect neuroendocrine differentiation, or help to distinguish metastatic carcinoma from primary lung cancer. A positive immunostaining with CEA, Leu-M1, SP1, B72-3 supports the diagnosis of pleural metastatic adenocarcinoma versus mesothelioma. Immunoscintigraphy is a non invasive imaging technique which allows local and distant disease evaluation and could replace in the future the present staging work up. To evaluate the potential therapeutic efficacy of MoAbs in Lung cancer, phase I studies have been performed. Therapeutic effect is based on: 1) indirect cytotoxicity (cells are killed by ADCC or K cells) or direct cytotoxicity (MoAb are carriers of toxins, radioisotopes or drugs). 2) Immune response modulation by anti-idiotypic Ab. 3) Interferences with growth factors. Results of most of phase I trials are disappointing. Improvement of MoAb selectivity, improvement of conjugates stability, reduction of humoral response to MoAb, enhanced tumour localisation, and reduction of nonspecific captation should lead to a better efficacy.