Reference equations for specific airway resistance in children: the Asthma UK initiative.

Plethysmographic specific airway resistance (sR(aw)) is a useful research method for discriminating lung disease in young children. Its use in clinical management has, however, been limited by lack of consensus regarding equipment, methodology and reference data. The aim of our study was to collate reference data from healthy children (3-10 yrs), document methodological differences, explore the impact of these differences and construct reference equations from the collated dataset. Centres were approached to contribute sR(aw) data as part of the Asthma UK initiative. A random selection of pressure-flow plots were assessed for quality and site visits elucidated data collection and analysis protocols. Five centres contributed 2,872 measurements. Marked variation in methodology and analysis excluded two centres. sR(aw) over-read sheets were developed for quality control. Reference equations and recommendations for recording and reporting both specific effective and total airway resistance (sR(eff) and sR(tot), respectively) were developed for White European children from 1,908 measurements made under similar conditions. Reference sR(aw) data collected from a single centre may be misleading, as methodological differences exist between centres. These preliminary reference equations can only be applied under similar measurement conditions. Given the potential clinical usefulness of sR(aw), particularly with respect to sR(eff), methodological guidelines need to be established and used in prospective data collection.

How do COPD and healthy-lung patients tolerate the reduced volume ventilation strategy during OLV ventilation.

BACKGROUND: Although a strategy of tidal volume (V(t)) reduction during the one-lung ventilation (OLV) period is advised in thoracic surgery, the influence of the pre-operative respiratory status on the tolerance of this strategy remains unknown. Therefore, the aim of this study was to compare the pulmonary function between chronic obstructive pulmonary disease (COPD) and healthy-lung patients during the operative and the post-operative period. METHODS: Forty-eight patients undergoing a planned lobectomy for cancer and presenting either a healthy lung function (n=24) or a moderate COPD stage (n=24) were ventilated without external positive end-expiratory pressure (PEEP) and received 9 ml/kg V(t) during the two-lung ventilation (TLV) period, secondary reduced to 6 ml/kg during the OLV period. Lung function was assessed by peroperative gas exchange, venous admixture, respiratory mechanical parameters and post-operative spirometric measurements. RESULTS: Although the PaO(2) was superior in the healthy-lung group during the TLV, once the OLV was established, no difference was observed between the two groups. Moreover, the PaO(2)/FiO(2) was proportionally more impaired in the healthy-lung group compared with the COPD group (50 ± 13 vs. 72 ± 19% of the baseline values after exclusion and 32 ± 15 vs. 51 ± 25% after the thoracotomy, P<0.05 for each) as well as the venous admixture. In the post-operative period, a higher decrease was observed in the healthy-lung group for the forced vital capacity and the forced expiratory volume. CONCLUSIONS: Reducing V(t) to 6 ml/kg without the adjunction of external PEEP during OLV is associated with better preservation of lung function in the case of moderate COPD than in the case of healthy-lung status.

Lung size matching for double lung transplantation based on the submammary thoracic perimeter. Accuracy and functional results. The Joint Marseille-Montreal Lung Transplant Program.

The present study evaluates the accuracy of submammary thoracic perimeter for lung size matching between donor and recipient and analyzes the influence of donor lung size discrepancies on functional outcome after double lung transplantation. The population is composed of 18 double lung graft recipients, 16 of whom had cystic fibrosis. The lung size match was assessed by comparison of predicted total lung capacity of donor and recipient: five patients were matched in a 10% confidence interval; four received smaller lungs, and nine received larger ones. The functional outcome was assessed with the spirometric values measured at 3 and 6 months after transplantation. The final functional result was not influenced by the lung size (r = 0.142 for total lung capacity; r = 0.372 for vital capacity; r = 0.378 for forced expiratory volume in 1 second). For larger lungs the final result tended to the recipient's predicted, whereas for smaller lungs, spirometry tended to the donor's predicted (r = 0.906 for total lung capacity; r = 0.875 for vital capacity; r = 0.874 for forced expiratory volume in 1 second). The thoracotomy effect, that is, restrictive syndrome at 3 months that resolves at 6 months, was not correlated with the lung size (r = 0.07 for total lung capacity; r = 0.436 for vital capacity). It is concluded that respiratory functional result is not affected by larger lungs; despite the wide range of error, the submammary thoracic perimeter appeared to be a satisfactory selection parameter in this group of patients.

Pulmonary function changes 100 days and one year after bone marrow transplantation.

The pulmonary function of patients receiving autologous or allogeneic bone marrow transplantation (BMT) was studied before, 100 days after and 1 year after BMT. The 117 patients studied before transplantation showed a slight reduction in average total lung capacity (TLC) and transfer coefficient (KCO). These reductions were related to haematological disease, previous pulmonary disease or irradiation, or use of toxic lung chemotherapy. Studies 100 days after BMT showed TLC and KCO decreases of 5% and 8%, respectively. These decreases were related to different factors in autologous and allogeneic BMT. The results were influenced by previous pulmonary status in autologous BMT patients and the occurrence of GVHD in allogeneic BMT patients. Seventy patients underwent pulmonary function testing 1 year after BMT. The decrease in TLC values was greater in autologous BMT than in allogeneic BMT patients (107 +/- 3% to 100 +/- 3% versus 113 +/- 3% to 112 +/- 2%, respectively) although TLC remained normal in both groups. KCO values dropped significantly in both populations. Relapse of the initial disease was an important factor impairing lung function in the autologous group. TLC and KCO changes were strongly related to mortality in both groups. These results emphasise the need for frequent pulmonary function tests after BMT to detect and quantify lung function changes.

Development of lymphocytotoxic antibodies among lung transplant recipients: preliminary results.

The aim of this study was to evaluate the incidence of postoperative lymphocytotoxic antibodies (LA) formation and to assess their potential utility in immunologic monitoring after lung transplantation. We determined prospectively the percentage LA against a reference panel reactive antibody in a complement-dependent microlymphocytotoxicity test in 137 sequential serum samples obtained from 14 consecutive lung transplant recipients who survived over the first postoperative year. Four patients developed high titers of LA (greater than 10% panel reactive antibody reactivity in at least 3 consecutive samples) by 2 to 24 months after surgery. Antibodies were mostly immunoglobulin M isotype, without any specificity against the donor's human leukocyte antigen and were correlated with the development of bronchiolitis obliterans syndrome (p=.01) and with chronic bronchial infectious colonization (p=.03). In conclusion, a polyclonal immunoglobulin M antibody production can be detected in serum samples from lung transplant recipients and seems to be involved in the progression of chronic rejection process. These preliminary results incline to carry on the cytotoxicity screening of a panel of lymphocytes to better understand the significance of such reactivity.

Cholinergic responsiveness of respiratory and vascular tissues in two different rat strains.

The airway and systemic arterial smooth muscle responsiveness to cholinergic agents of two strains of rats, Rat Albino (RA) and Brown Norway (BN), was compared in vivo and in vitro. In vivo, we measured the doses of carbachol that induced a 100% increase in lung resistance (PD100 RL), a 50% decrease in dynamic lung compliance (PD50 Cdyn), and the value of systolic blood pressure at the carbachol dose of 10 micrograms (Pa 10 micrograms). In vitro airway smooth muscle and systemic arterial smooth muscle responsiveness was assessed by measuring the maximal response to acetylcholine, the slope of the linear portion of the dose-response curve, and the negative logarithm of the molar concentration of acetylcholine producing 50% of the maximal response (pD2). PD100 and PD50 were about four times greater in BN rats than in RA rats. In contrast, Pa 10 micrograms was 1.5 lower in the BN rats. These differences persisted after bivagotomy. Tracheal pD2 was 25% greater in the RA than in the BN strain. The mean dose-response curve of parenchymal strips of RA rats was situated upward and to the left of the BN curve, but the reverse was observed for aortic smooth muscle dose-response curves. Thus 1) airway smooth muscle responsiveness to cholinergic agents is greater in RA strain than in BN, but the reverse is true for systemic arterial smooth muscle responsiveness; and 2) these differences are not due to factors extrinsic to the smooth muscle, since they occurred in vitro and may depend on different densities of muscarinic receptors.

Tonic activity in inspiratory muscles and phrenic motoneurons by stimulation of vagal afferents.

In anesthetized rabbits, direct and integrated phrenic neurogram (Ephr) and electromyograms from the diaphragm (Edi) and intercostal (Eic) (2nd space) and transversus abdominis muscles (Etr) were simultaneously recorded in two protocols. 1) In animals breathing spontaneously, we used infinite inspiratory (RI) or expiratory (RE) resistive load and intravenous injections of carbachol, histamine, or phenyl diguanide (PDG). All circumstances except RE evoked tonic activities in Ephr, Edi, and Eic but never in Etr. Intravenous atropine abolished carbachol-induced bronchoconstriction and associated tonic inspiratory activities, but this effect persisted with RI, histamine, and PDG. Selective procaine block of conduction in thin vagal fibers (with persistence of the Breuer-Hering inflation reflex) reduced or suppressed the tonic response, which was abolished in all cases after vagotomy. 2) In rabbits artificially ventilated with open chest, passive deflation of the lung or intravenous injections of histamine or PDG also produced tonic discharge in Ephr and often in Eic. The present results demonstrate that 1) stimulation of vagal afferents and mostly thin sensory fibers elicits tonic inspiratory discharges, 2) bronchoconstriction is not necessary for the induction of the response, and 3) reflexes from the chest wall do not mediate this response in rabbits.

Bronchial challenge with carbachol in 3-6-year-old children: body plethysmography assessments.

Several studies of airway responsiveness in young children (3-6 years old) have been reported, but few have attempted measurements of airway resistance by body plethysmography. Therefore, we decided to study nonspecific bronchial responsiveness following cumulative doses of inhaled carbachol in 44 children with clinical asthma (CA group), 44 children with chronic cough (CC group), 38 children with wheezy bronchitis in the first 2 years of life (WB group), and 40 controls. Specific airway resistance (sRaw) was measured in a body plethysmograph, and specific airway conductance (sGaw=1/sRaw) was calculated. Two parameters were used to assess individual bronchial responses: 1) PD100 (the dose of carbachol which induced a 100% increase in sRaw), and 2) bronchial reactivity (BR), i.e., the slope of the log-dose sGaw response to carbachol. Significant differences were observed in PD100 and BR between the control group and the three groups of young patients (P < 0.001). Moreover, PD100 of the CA group was significantly lower than in the CC group (83.1 +/- 7.8 microg vs. 108.0 +/- 10.2 microg, respectively, P < 0.05), but was similar to the WB group PD100 (94.4 +/- 8.5 microg). BR in the CA group was significantly higher than in both the CC and WB groups (0.127 +/- 0.009 cm H2O-L.sec(-1) x log microg(-1) vs. 0.073 +/- 0.006 cm H2O(-1) x sec(-1) x log microg(-1) and 0.082 +/- 0.006 cm H2O(-1) x sec(-1) x log microg(-1), respectively, P < 0.001). Repeatability and coefficients of variation were always acceptable. Continuous SaO2 monitoring in some children of the CA group demonstrated the safety of the method, which is proposed as a technique in future studies.

Impairment of muscle energy metabolism in patients with sleep apnoea syndrome.

Impairment of muscle energy metabolism has been demonstrated in normal subjects with chronic hypoxaemia (altitude chronic respiratory failure). The purpose of this study was to verify the hypothesis that a comparable condition could develop in patients with sleep apnoea syndrome (SAS), considering that they are exposed to prolonged and repeated hypoxaemia periods. Muscle metabolism was assessed in 11 patients with SAS performing a maximal effort on cycloergometer. In comparison with normal subjects, SAS patients reached lower maximal loads [144 +/- 7 vs. 182 +/- 10 W (P < 0.005)] and lower peak oxygen uptakes [26.4 +/- 1.2 vs 33.2 +/- 1.4 ml kg-1 min-1 (P < 0.005)]. Abnormal metabolic features were found: maximal blood lactate concentration was significantly lower than in normal subjects [0.034 +/- 0.004 vs. 0.044 +/- 0.002 mmol l-1 W-1 (P < 0.05)]; and lactate elimination rate, calculated during a 30-min recovery period, was reduced [0.127 +/- 0.017 vs, 0.175 +/- 0.014 mmol l-1 min-1 (P < 0.025)]. The extent of these anomalies correlated with the severity of SAS. The patients also showed higher maximal diastolic blood pressures than normal subjects [104 +/- 5 vs. 92 +/- 4 mmHg (P < 0.05)]. These results can be interpreted as indications of an impairment of muscle energy metabolism in patients with SAS. Decrease in maximum blood lactate concentration suggests an impairment of glycolytic metabolism, while decrease in the rate of lactate elimination indicates a defect in oxidative metabolism. Since no respiratory pathology apart from SAS was found in this group of patients, it seems legitimate to link the genesis of these impairments to repeated bouts of nocturnal hypoxaemia.

Electrostatic charge on spacer devices and salbutamol response in young children.

Electrostatic charge on plastic spacer devices may affect the efficacy of inhaled drugs, but its consequences have never been evaluated in asthmatic children with airflow limitation. At the end of a positive metacholine challenge, 64 children (51.3+/-12.9 months, 32 boys, specific airway resistance (SRaw) 257.1+/-56.7% and forced expiratory volume in 1s (FEV(1)) 64.2+/-17.9% of the predicted value) inhaled one puff of hydrofluoroalkane-134a (HFA-134a) salbutamol (Ventoline((R))), and 15min later two other puffs (total dose of 300 microgram), delivered through either a new static Babyhaler((R)) (n=21), a detergent-coated, reduced static, Babyhaler((R)) (n=20), or a metal NES-Spacer((R)) (n=23) equipped with facemask. SRaw and FEV(1) were measured after each treatment and compared between groups by a Kruskal-Wallis test. The first 100 microgram salbutamol induced a 151.7+/-43.9% decrease in SRaw and a 19.9+/-10.6% increase in FEV(1). Additional 200 microgram salbutamol allowed a supplementary decrease of 35.1+/-25.7% in SRaw and increase of 12.1+/-11.8% in FEV(1), without significant difference between the spacer devices. Electrostatic charge on spacer devices does not affect bronchodilation with HFA-134a salbutamol in metacholine-challenged pre-school children. This could be in part explained by the use of supramaximal doses of salbutamol.

Increased diaphragmatic strength and tolerance to fatigue after bilateral lung transplantation: an electromyographic study.

We evaluated the diaphragmatic function of seven patients with severe chronic respiratory failure before and after a bilateral lung transplantation (BLT), with follow-up at one year of pulmonary function tests, maximal inspiratory mouth pressure (MIP) and surface diaphragmatic electromyogram (Edi). The patients were asked to sustain target inspiratory pressures at -15, -30, and -50 cmH(2)O. We measured the endurance time (Tlim) to sustain inspiratory efforts and the power spectrum density function of Edi at each inspiratory maneuver. The Edi power spectra was analysed in terms of median frequency (MF), total power (TP) and energies in high-and low-frequency bands (EL and EH). Before BLT, a defect of the diaphragmatic function was evident: MIP was 62+/-7% of the predicted value and the Tlim measured at each inspiratory effort was very short ( 13+/-1 s, 10+/-1 s and 8+/-1 s at pressures of -15, -30, and -50 cmH(2)O, respectively). One month after BLT, the Tlim began to increase at all target inspiratory pressures and at 6 months MIP recovered to normal values. One month after BLT, there was a significant decrease in TP measured at the beginning of each inspiratory efforts and also an increase in the concomitant MF value. BLT markedly accentuated the maximal variations of TP, MF and low-frequency Edi energy. Some hypotheses are raised to explain this dramatic improvement in diaphragmatic function after BLT.

[Shrinking lung syndrome and systemic auto-immune disease]. / Le syndrome des poumons rétractés et les maladies auto-immunes.

INTRODUCTION: Shrinking lung syndrome usually manifest in dyspnea, decreased lung volume associated with elevated diaphragm. It reports with systemic autoimmune disease and physiopathological mechanism is controversial. EXEGESIS: We report three shrinking lung syndrome observations in which two cases were diagnosed at the time to onset of autoimmune disease. The three patients were treated with corticosteroid, two of them necessitated theophylline. Review of the literature highlight 60 cases and permit to discuss physiopathological mechanisms which remain uncertain. Diaphragmatic dysfunction (because of myositis or neuropathy) represented by abnormal transdiaphragmatic pressures is actually discussed. CONCLUSION: Shrinking lung syndrome is rare but must be considered in patient with autoimmune disease and dyspnea. The diagnosis can be difficult because of clinical, pathological and functional features which are controversial. The optimum treatment is unknown.

[Gastroesophageal reflux and respiratory manifestations: diagnostic approach, therapeutic indications and results]. / Reflux gastro-oesophagien et manifestations respiratoires: attitude diagnostique, indications thérapeutiques et résultats.

The authors report a study of 140 patients presenting with a non-allergic respiratory tract disease (121 cases of asthma--19 cases of spasmodic cough). Gastro-oesophageal reflux was detected by 24-hour pHmetry in 86 of these patients. In 34 of them (i.e. 40% of cases), the gastro-oesophageal reflux appeared to be responsible for the initial respiratory tract symptoms. These 34 patients were submitted to a therapeutic trial of high dose anti-H2 therapy for at least two months. Only those patients in whom a marked improvement or even complete resolution of the respiratory tracts symptoms was observed underwent anti-reflux surgery. Out of the 13 patients undergoing surgery, there were two failures and 11 good results after a follow-up of more than 18 months.

[Study of tracheobronchial healing after lung and heart-lung transplantation. Apropos of 64 anastomoses]. / Etude de la cicatrisation trachéo-bronchique après transplantations pulmonaires et cardio-pulmonaires. A propos de soixante-quatre anastomoses.

The authors report an analysis concerning the healing of tracheo-bronchial anastomoses after lung- and heart-lung transplantation. The present study includes 64 anastomoses selected from a total of 80 cases. Sixteen had to be excluded because of early post-operative death; none of these deaths was related to an air-way complication. Bronchial healing was assessed by bronchoscopic follow-up; the appearance of the suture-line was classified according to Couraud's grades. The initial reference was the examination at 2 weeks, which was compared to subsequent follow-up. At the initial assessment, 42 anastomoses were grade I, 4 were grade II, and 18 were grade III. The subsequent anatomic result was satisfactory for 52 sutures (81%). The complications were malacia in 2 cases, stenoses treated with a stenting device in 4 cases, dehiscence in 6 cases. The duration of ischemia and post-operative mechanical respiratory support, as well as the proximal or distal site of the anastomosis appeared to be of significant prognostic value.

[Tracheobronchial healing after lung and heart-lung transplantations. Apropos of 64 anastomoses]. / Etude de la cicatrisation trachéo-bronchique après transplantations pulmonaires et cardio-pulmonaires. A propos de 64 anastomoses.

The authors report an analysis concerning the healing of tracheo-bronchial anastomoses after lung- and heart-lung transplantation. The present study includes 64 anastomoses selected from a total of 80 cases. Sixteen had to be excluded because of early post-operative death; none of these deaths was related to an air-way complication. Bronchial healing was assessed by bronchoscopic follow-up; the appearance of the suture-line was classified according to Couraud's grades. The initial reference was the examination at 2 weeks, which was compared to subsequent follow-up. At the initial assessment, 42 anastomoses were grade 1, 4 were grade II, and 18 were grade III. The subsequent anatomic result was satisfactory for 52 sutures (81%). The complications were malacia in 2 cases, stenoses treated with a stenting device in 4 cases, dehiscence in 6 cases. The duration of ischemia and postoperative mechanical respiratory support, as well as the proximal or distal site of the anastomosis appeared to be of significant prognostic value.

[Bronchial provocation tests. Comparison of 2 inhalation methods]. / Tests de provocation bronchique. Comparaison de deux méthodes d'inhalation.

This study was performed to compare two methods of aerosols delivery and inhalation in a bronchial provocation test with carbachol : the stocked method (S) where the aerosol is previously stocked in a spirometer bell before inhalation and the dosimeter method (D) where the aerosol is directly inhaled after nebulization. Fourteen subjects (seven normal and seven asthmatic) underwent bronchial challenges with the two techniques. Bronchial sensitivity was calculated on SRaw-dose response curves to carbachol. SGaw-dose response curves were also constructed and the slopes of these curves were used to measure bronchial reactivity. Within subjects sensitivity values were lower with the D method than with the S method (40 +/- 5 micrograms (S E) versus 450 +/- 50 micrograms respectively in asthmatics, 340 +/- 30 micrograms versus 2350 +/- 130 micrograms respectively in healthy subjects). Reactivity values were higher with the dosimeter method (2,7 +/- 0,7 x 10(-5) versus 27 +/- 4 x 10(-5) in healthy and 10 +/- 1 x 10(-5) versus 106 +/- 16 x 10(-5) in asthmatics). The dosimeter method had greater efficacy, was less time consuming and appeared to be a useful method for carrying out standardised non-specific bronchoprovocation test.

[Medical history of severe respiratory insufficiency]. / Histoire médicale des insuffisants respiratoires graves.

To evaluate retrospectively health care in severe chronic respiratory failure, we interviewed 38 patients, admitted for the first time to a pulmonary intensive care unit for an acute episode. A standardised questionnaire was devoted to establishing if the patients were aware of chronic respiratory disease prior to admission, if they had visited a general practitioner or a chest clinic, and had undergone a lung function evaluation. Six patients were unaware of any respiratory disease prior to the acute episode. Six others realised they had suffered from a respiratory disease, but had failed to visit a physician. Among the remaining 26 patients, two-thirds had visited a chest physician. Fourteen of them had undergone spirometry and arterial blood gas measurements. One third had visited a general practitioner but spirometry was performed in only 3 and arterial blood gas analysis in only 1. Thus, chronic respiratory failure is sometimes ignored, and most of the time diagnosed with delay and inadequately evaluated.

[Trial of a new technic of transcutaneous diaphragmatic electrostimulation in man]. / Essai d'une nouvelle technique d'électrostimulation diaphragmatique transcutanée chez l'homme.

A new method of diaphragmatic pacing by transcutaneous electrical stimulation, using alternative currents with frequency and amplitude modulations, was tested in 12 subjects: 3 were normal and awake (group I); 4 were studied in acute respiratory failure while under mechanical ventilation and central apnea (group II) and 5 were studied while anaesthetized for peripheral venous surgery and breathing spontaneously (group III). Stimulation was performed either during spontaneous ventilation (groups I and II) or during short periods of respiratory depression (group III). Tidal volume was measured by pneumotachography. A positive correlation was found between stimulus intensity and inspired volume. This effect was not due to voluntary control alone, since diaphragmatic stimulation could support 24% of the theoretical minute ventilation in group II subjects and 64% in group III subjects. These preliminary results demonstrate the relative efficacy of this new method of diaphragmatic pacing using computerized alternative currents.

[Induced sputum as a new approach of the assessment of inflammation in asthma]. / L'analyse de l'expectoration induite dans l'asthme permet une nouvelle approche de l'inflammation.

Asthma is an inflammatory condition. Traditionally bronchoalveolar lavage and bronchial biopsies obtained by bronchoscopy have been used to demonstrate inflammation. Induced-sputum is a non-invasive, reliable, reproducible and safer technique for monitoring inflammatory activity in patients with asthma. Studies have shown that induced-sputum measures aspects of inflammation distinct to that measured by bronchoalveolar lavage or bronchial biopsies. Numerous studies have suggested that induced-sputum is a potentially useful tool for early diagnosis of exacerbation, monitoring of therapy, identification of the lowest effective dose and assessing compliance in asthmatics. In this respect, we suggest that this test can be routinely used in the management of difficult asthmatics.

[Lung transplantation and respiratory function tests. Functional outcome in the presence and absence of chronic rejection]. / Transplantations pulmonaires et EFR. Evolution fonctionnelle en présence ou en l'absence de rejet chronique.

Between may 1988 and march 1993, twenty five double lung transplants were performed and five heart/lung transplants. Lung function tests (EFR) were performed on these patients for a period of 19.2 +/- 3.4 months. The aim of this study was two-fold. First, to report our overall results and to estimate the role of the single breath nitrogen washout test (N2 slope) in the early detection of chronic rejection (RC). Secondly, to assess the diagnostic value of EFR in the discrimination of acute rejection (RA) and of cytomegalovirus pneumonitis (PCMV). There were 41 episodes of RA and 21 episodes of PCMV and they were analysed as a function of the presence or absence of RC. In the absence of RC, RA produced no change in EFR and PCMV was accompanied by a pure restrictive ventilatory defect. On the otherhand, RA and PCMV lead to a worsening of obstruction and an hypoxaemia which characterises RC. The diagnosis of RC was made, on average, 14.4 +/- 2.9 months after surgery. However, from the sixth month the nitrogen slope was significantly increased and other parameters of EFR (particular maximal flows at low lung volume) remained normal. Thus, our results suggest that the N2 slope, measured in the absence of any evidence of acute rejection, constitutes an early test for chronic rejection. When its pathological rise is compared to the results of histology (presence or absence of RC), it shows a sensitivity of 0.94 and a specificity of 0.93.