Recommendations for the prevention and diagnosis of asthma in children: Evidence from international guidelines adapted for Mexico.

BACKGROUND: With the availability of high-quality asthma guidelines worldwide, one possible approach of developing a valid guideline, without re-working the evidence, already analysed by major guidelines, is the ADAPTE approach, as was used for the development of National Guidelines on asthma. METHODS: The guidelines development group (GDG) covered a broad range of experts from medical specialities, primary care physicians and methodologists. The core group of the GDG searched the literature for asthma guidelines 2005 onward, and analysed the 11 best guidelines with AGREE-II to select three mother guidelines. Key clinical questions were formulated covering each step of the asthma management. RESULTS: The selected mother guidelines are British Thoracic Society (BTS), GINA and GEMA 2015. Responses to the questions were formulated according to the evidence in the mother guidelines. Recommendations or suggestions were made for asthma treatment in Mexico by the core group, and adjusted during several rounds of a Delphi process, taking into account: 1. Evidence; 2. Safety; 3. Cost; 4. Patient preference - all these set against the background of the local reality. Here the detailed analysis of the evidence present in BTS/GINA/GEMA sections on prevention and diagnosis in paediatric asthma are presented for three age-groups: children with asthma ≤5 years, 6-11 years and ≥12 years. CONCLUSIONS: For the prevention and diagnosis sections, applying the AGREE-II method is useful to develop a scientifically-sustained document, adjusted to the local reality per country, as is the Mexican Guideline on Asthma.

Can a normal peak expiratory flow exclude severe chronic obstructive pulmonary disease?

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is underdiagnosed. One barrier to diagnosis is the limited availability of spirometry testing, but in adults at risk for COPD, a normal pre-bronchodilator (pre-BD) peak expiratory flow (PEF) may rule out clinically significant COPD. OBJECTIVE: To identify post-BD airway obstruction using data from 13 708 individuals aged >or=40 years from the PLATINO and BOLD studies. METHODS: We evaluated different cut-off points of pre-BD. The PEF was obtained from a diagnostic-quality spirometer (not a mechanical PEF meter). At least one of the following COPD risk factors was present in 77% of the subjects: chronic respiratory symptoms; exposure to tobacco smoke, biomass smoke or dust in the workplace; or a previous diagnosis of asthma, COPD, emphysema or chronic bronchitis. RESULTS: Although the positive predictive value was low as expected, a pre-BD PEF of >or=70% predicted effectively ruled out Stages III and IV COPD of the Global Initiative for Chronic Obstructive Lung Disease. Among those with at least one risk factor, only 12% would require confirmatory spirometry using this criterion. CONCLUSIONS: Adding PEF measurement to a screening questionnaire may rule out severe to very severe COPD without the need for pre- and post-BD spirometry testing. Confirmation is needed from a study using inexpensive PEF meters or pocket spirometers with a staged screening protocol.

Preoperative continuous positive airway pressure compliance in children with obstructive sleep apnea syndrome: assessed by a simplified approach.

INTRODUCTION: The frequency of diagnoses of obstructive sleep apnea syndrome (OSAS) in children is increasing and more and more adenotonsillectomies (A&T) are being performed on severely ill children who have a higher perioperatory risk. The objective of the present study was to describe preoperative compliance in the use of continuous positive airway pressure (CPAP) in children with OSAS, when this treatment was prescribed as a means of preventing complications. PATIENTS AND METHODS: We describe data from children with severe OSAS caused by hypertrophy of the adenoids and tonsils, but with no craniofacial abnormalities. CPAP pressure was adjusted either during diurnal polysomnography with sleep deprivation or by self-adjusting devices. Follow-up was conducted through weekly interviews and the downloading of data recorded by the equipment. RESULTS: 48 children were included; 73% of them used a CPAP machine > or =3h per night, and 31% used it for > or =6h per night. The variables associated with good equipment compliance included higher BMI, higher pressure levels in the devices, and a higher number of episodes of apneas and hypopneas. Children who weighed > or =30kg used CPAP for > or =3h per night more often (OR 16, 95% CI 1.9-137). Compliance levels with fixed and self-adjusting CPAP were similar, and side effects in both cases were slight and limited to those caused by the pressure of the masks on patients' skin. One case of excessive bleeding was the only complication reported during A&T. CONCLUSIONS: The mean preoperative use of CPAP equipment by children with severe OSAS was 4.5+/-2.6h. Seventy-three percent of subjects used the equipment for >/=3h.

[Descriptors of breathlessness in Mexican Spanish]. / El lenguaje de la disnea. Una visión desde el español de México.

OBJECTIVE: Breathlessness is the most common symptom of cardiovascular or pulmonary disease. The term encompasses a wide range of descriptors used by patients, however. Identifying those descriptors can be useful for analyzing symptoms and understanding how they arise. The aim of this study was to characterize the descriptors of breathlessness used in Mexican Spanish and to consider their association with various states of respiratory distress and cardiovascular or pulmonary disease. MATERIAL AND METHODS: A questionnaire was based on 21 descriptors of breathlessness, some of which had no equivalents in English. The subjects included 15 healthy individuals during a cardiopulmonary stress test, 13 healthy subjects after a carbon dioxide rebreathing procedure, and 10 healthy women during pregnancy. We also included 16 patients with confirmed heart disease in stable condition, 15 patients during exacerbation of asthma, 20 with stable chronic obstructive pulmonary disease, and 15 with diffuse interstitial lung disease also in stable condition. Descriptors of breathlessness were then grouped based on the results of cluster analysis. RESULTS: Seven clusters of phrasal descriptors were identified as possibly representative of types of dyspnea. These clusters of descriptors were categorized as follows: agitation, suffocation, smothering, inhalation, exhalation, panting, and rapidity. Associations between types of dyspnea and the groups of participants were identified based on how frequently they used the terms. CONCLUSIONS: At least 7 clusters or groups of descriptors of breathlessness were identified as equivalent to 7 types of dyspnea; some items have no equivalent in English. Healthy subjects with respiratory distress or certain groups of patients with cardiovascular or pulmonary disease are associated with certain types of dyspnea.

[Reproducibility of spirometry in Mexican workers and international reference values]. / Reproducibilidad de espirometrías en trabajadores mexicanos y valores de referencia internacionales.

OBJECTIVE: To describe spirometric function and adjustment to foreign prediction equations in Mexican workers claiming work related disability. MATERIAL AND METHODS: We reviewed 5771 spirometries done at the Mexican National Institute of Respiratory Diseases performed with equipment and methods proposed by the American Thoracic Society. With the spirometries we generated multiple regression equations separated for men and women based on age and height, compared to other in common use reported by Knudson and Hankinson in North America and by Quanjer in europeans. RESULTS: 80% of the tests were reproducible for FVC and FEV1 according to ATS, whereas 10% were reproducible for neither. Mean FVC in men was 12% above values reported by Quanjer, 22% above Knudson, 3% above Hankinson and 6% above Rodriguez-Reynaga, whereas similar values for women were 18%, 10%, 0% and 1%. Excluding obese and those who had less than 2 acceptable maneuvers, the numbers increase by 1-2%. FEV1 was also above predicted. CONCLUSIONS: Most workers requesting disability are able to generate a reproducible spirometry. However for the same gender, age and height, workers had a FEV1 and a FVC above normal values reported by Knudson and Quanjer and are more similar to those reported by Hankinson in Mexican-Americans. While a set of appropriate reference values are obtained, regression equations obtained from the studied group will generate less error in the evaluation of disability in mexican workers. The English version of this paper is available at: http://www.insp.mx/salud/index.html.

[Estimation of gasometric values at different altitudes above sea level in Mexico]. / Estimación de los valores gasométricos en diferentes alturas sobre el nivel del mar en México.

We calculated reference values for arterial blood gases at different altitudes in Mexico assuming that sea level PaCO2 is 40 Torr, and in Mexico City (2.24 km. above the sea level) is 31.13 Torr, average of reported reference values. With the previous two points, it is possible to calculate a linear regression: PaCO2 = 40-3.96(altitude in km.). The equation is very similar to that calculated from reports in alveolar gas in North-Americans (Fitzgerald < 5 km): PACO2 = 39.3-3.11(altitude in km), and from subjects acclimatized to acute altitude exposure (< 5 km): PACO2 = 38.3-2.5 (altitude in km). It is also similar to a alinear equation that can be calculated assuming that hyperventilation in permanent habitants of moderate altitudes is inversely proportional to inspired molar concentration of O2: PaCO2 = PIO2/3.74. On the other hand, the equation is very different than that obtained from Andean natives (Hurtado): PaCO2 = 40.4-1.35(altitude in km). The proposed linear equation for Mexico gives very similar results (< 2 Torr difference) than a complex curvilinear equation by Morris et al. appropriate only up to 2.3 km. Evidence from acute exposure to altitude (acclimatized) and in North-Americans (alveolar gas) supports a reasonably accurate linear relationship up to 4 km. and also that the increase in ventilation in response to moderate altitudes in adult permanent residents is inversely proportional to molar concentration of O2. PAO2 was calculated with alveolar gas equation and resting the P(A-a)O2 we obtained PaO2. In conclusion, according to reference values in Mexico City, PaCO2 decreases about 4 Torr per km of altitude above the sea level. The decrease is similar to that reported in North-Americans and in acute exposure to altitude (acclimatized), but much less than that reported in native Peruvians. Ventilation is inversely proportional to the molar concentration of O2 at least up to an altitude where SaO2 is at or above 90%.

[The surgical risk in sleep apnea: the implications for tonsillectomies]. / Riesgo quirúrgico en la apnea del sueño: implicaciones para las amigdalectomías.

Hypertrophy of tonsils or adenoids is the commonest cause of obstructive sleep apnea (OSA) in children. Adenotonsillectomy (AT) is frequently curative in children with OSA but riskier than the same procedure without OSA. It is crucial to identify OSA among the patients programmed for AT because they require a detailed evaluation, frequently including total or limited polysomnogram. Patients with OSA need a continuous surveillance before, during, and after surgery, ideally in a referral hospital.

[Normal ventilatory response to hypoxia and hypercapnia at an altitude of 2240 meters]. / Respuesta ventilatoria normal a hipoxia e hipercapnia a una altitud de 2240 metros.

OBJECTIVE: To evaluate the ventilatory response to hypoxia and hypercapnia in healthy residents of Mexico City at 2240 m above sea level. METHODS: 15 healthy subjects, 10 women and 5 men, were studied (mean age 38; range 26-76). All completed one or two tests of ventilatory response to hypoxia and hypercapnia as described by Rebuck-Campbell and Read, respectively. The results were analyzed by linear regression using the minute ventilation as the dependent variable and SaO2 (hypoxia) or PCO2 (hypercapnia) as the independent variables. RESULTS: Seven subjects had very low or no response to hypoxia. The mean hypoxia slope was 0.7 +/- 0.6 L/min/% (+/- SD) and the hypercapnia slope was 3.0 +/- 1.4 L/min/mmHg. The intercepts were 176 +/- 278 for SaO2 and 3.0 +/- 7 for PCO2. CONCLUSIONS: A low respiratory response to hypoxia was found in Mexico City Healthy residents. The response to hypercapnia was similar in slope to other studies but had an intercept shifted to lower values. The Mexico City residents showed a behavior typical of patients with chronic hypoxemia or of dwellers at high altitudes.

[Diagnostic usefulness of bronchoalveolar lavage in nosocomial pneumonia associated with mechanical ventilation in patients undergoing antibiotic treatment]. / Utilidad diagnóstica del lavado broncoalveolar en la neumonía nosocomial asociada con ventilación mecánica en pacientes bajo tratamiento antibiótico.

We evaluated the diagnostic utility of the colony forming units (CFU) count in bronchoalveolar lavage (BAL) cultures from patients with nosocomial pneumonia associated with mechanical ventilation (PAMV) and treatment with systemic antibiotics. Cultures with greater than 10(4) CFU/ml were considered positive, while the absence of cultures was considered negative. Cultures with < or = 10(3) CFU/ml were classified as contaminated. The gold standard was defined by clinical, bacteriological, and histological criteria. We studied 12 patients suspected of having PAMV, and six controls who had no evidence of pneumonia or infection of any kind. Positive cultures were found in all patients suspected of having PAVM, while all controls had negative cultures. One patient was eliminated because we were unable to corroborate the final diagnosis. Using the gold standard, nine patients had PAVM, and eight did not have PAVM. The sensitivity of the test was 100%, and the specificity was 75%, while the positive predictive value was 88%, and the negative predictive value 100%. We conclude that the CFU count in BAL cultures is a useful method for the diagnosis of PAMV in patients treated with systemic antibiotics.

[Tuberculosis associated with HIV infection]. / Tuberculosis asociada a infección por el virus VIH.

Tuberculosis and human immunodeficiency virus (HIV) infection are two important linked public health problems in the world of today. Tuberculosis in HIV infected patients is frequently atypical in its clinical and radiological findings and commonly has an extrapulmonary dissemination. Atypical mycobacteriosis have also been reported in patients with HIV infection. We review here all the patients admitted from 1986 to 1991 with definitive diagnosis of tuberculosis and HIV infection at the National Institute of Respiratory Diseases in Mexico City. Out of 220 patients with HIV infection and pulmonary complications, 19 had proven tuberculosis. Their mean age was 34 +/- 8 years and seven were homosexual males. In 16 patients (84%), respiratory symptoms (cough with sputum) and fever were the first manifestations of the HIV infection. Only two patients had the typical cavitary lesions but also coexisting with miliary tuberculosis. The rest had several types of non cavitated pulmonary opacities or other thoracic or pleural alterations. Eleven patients (58%) had, in addition, extrapulmonary tuberculosis. Mycobacterium tuberculosis was cultured in 11 of 12 patients but no atypical mycobacteria were isolated. Only seven of the 19 patients completed at least six months of treatment and two of them relapsed. Three patients died in their first admission; the rest were lost in the follow up. Our results show that the clinical features of tuberculosis associated to HIV infection are similar to those described in other countries.