Carbon dioxide rebreathing in non-invasive ventilation. Analysis of masks, expiratory ports and ventilatory modes.

BACKGROUND AND AIM: Carbon dioxide (CO2) rebreathing is a complication of non-invasive ventilation (NIV). Our objectives were to evaluate the ability of masks with exhaust vents (EV) to avoid rebreathing while using positive pressure (PP) NIV with different levels of expiratory pressure (EPAP). Concerning volume-cycled NIV, we aimed to determine whether cylindrical spacers located in the circuit generate rebreathing. MATERIALS AND METHODS: 5 healthy volunteers were evaluated. Bi-level PP was used with 3 nasal and 2 facial masks with and without EV. Spacers of increasing volume attached to nasal hermetic masks were evaluated with volume NIV. Inspired CO2 fraction was analyzed. RESULTS: Rebreathing was zero with all nasal masks and EPAP levels. Using facial masks 1 volunteer showed rebreathing. There was no rebreathing while using all the spacers. CONCLUSIONS: In healthy volunteers, nasal and facial masks with EV prevent rebreathing. In addition, the use of spacers did not generate this undesirable phenomenon.

Performance of mechanical ventilators at the patient's home: a multicentre quality control study.

BACKGROUND: Quality control procedures vary considerably among the providers of equipment for home mechanical ventilation (HMV). METHODS: A multicentre quality control survey of HMV was performed at the home of 300 patients included in the HMV programmes of four hospitals in Barcelona. It consisted of three steps: (1) the prescribed ventilation settings, the actual settings in the ventilator control panel, and the actual performance of the ventilator measured at home were compared; (2) the different ventilator alarms were tested; and (3) the effect of differences between the prescribed settings and the actual performance of the ventilator on non-programmed readmissions of the patient was determined. RESULTS: Considerable differences were found between actual, set, and prescribed values of ventilator variables; these differences were similar in volume and pressure preset ventilators. The percentage of patients with a discrepancy between the prescribed and actual measured main ventilator variable (minute ventilation or inspiratory pressure) of more than 20% and 30% was 13% and 4%, respectively. The number of ventilators with built in alarms for power off, disconnection, or obstruction was 225, 280 and 157, respectively. These alarms did not work in two (0.9%), 52 (18.6%) and eight (5.1%) ventilators, respectively. The number of non-programmed hospital readmissions in the year before the study did not correlate with the index of ventilator error. CONCLUSIONS: This study illustrates the current limitations of the quality control of HMV and suggests that improvements should be made to ensure adequate ventilator settings and correct ventilator performance and ventilator alarm operation.

Inspired oxygen fraction achieved with a portable ventilator: determinant factors.

INTRODUCTION: Non-invasive positive pressure ventilation (NIPPV) is an effective treatment in respiratory failure. Continuous positive pressure (CPAP) may also be useful in acute hypoxaemic patients. Supplementary oxygen is usually necessary in both systems. However, the inspired oxygen fraction (FiO2) delivered by a NIV portable ventilator is unknown. The main objectives of this study were to establish the maximal FiO2 that could be achieved by these devices and to analyse the FiO2 determinant factors. METHOD: Ten healthy volunteers were evaluated using a BiPAP ST30 ventilator (Respironics, USA) with a single-limb circuit, expiratory port and nasal mask (Respironics, USA). Oxygen (15 L/min) was administered at two connection points (proximal and distal). Each volunteer carried out a NIPPV (inspiratory pressure 20 cmH2O [1.95 kPa]-expiratory pressure 8 cmH2O [0.78 kPa]) and a CPAP (10 cmH2O [0.981 kPa]) session. FiO2 was analysed by a probe located in the mask. Minute volume (MV) was measured using a pneumotachograph. RESULTS: Maximal FiO2 was obtained with CPAP and distal oxygen connection point (67.39 +/- 15.39%). NIPPV achieved higher MV than CPAP. FiO2 was inversely correlated with MV. CONCLUSIONS: FiO2 obtained while using a NIPPV portable ventilator depends on the ventilatory assistant mode, the oxygen connection point and the MV reached.

Primary alveolar hypoventilation and XXXXY chromosopathy.

The association of primary alveolar hypoventilation (PAH) and chromosomic diseases has not been described previously. A 19 year-old man with Fraccaro's syndrome (XXXXY karyotype) was admitted to evaluate chronic hypercapnic respiratory failure, pulmonary arterial hypertension and cor pulmonale. PAH was diagnosed. As effective treatment, such as non-invasive positive pressure ventilation (NIPPV), is available for this disorder we should intensify the search for PAH in patients with chromosome disease.

[Efficacy of the 6-minute walk test in evaluating ambulatory oxygen therapy]. / Eficacia de la prueba de los 6 minutos de marcha en la valoración de la oxigenoterapia de deambulación.

OBJECTIVE: To compare oxyhemoglobin saturation (SpO2) observed during the 6-minute walk test with that of pulse oximetry carried out during activities of daily living (ADLs). The efficacy of the 6-minute walk test for determining adequate oxygen flow to prevent arterial desaturation during ADLs was also analyzed. PATIENTS AND METHODS: We studied 37 patients diagnosed with chronic obstructive pulmonary disease (COPD)--mean (SD) forced expiratory volume in 1 second, 26% (9%) of predicted--and compared SpO2 values obtained in the 6-minute walk test with those obtained with ambulatory pulse oximetry during ADLs. Eleven of the 20 patients with exercise-induced desaturation agreed to use portable liquid oxygen and were randomized to ambulatory pulse oximetry on 2 consecutive days, both with and without the administration of oxygen. Oxygen flow was adjusted on successive 6-minute walk tests until a mean SpO2 greater than 85% was reached. RESULTS: The mean SpO2 for all patients was 84% (7%) during the 6-minute walk test and 89% (4%) during ADLs (P<.001). Cumulative percentages of time with SpO2 less than 90%, 88%, and 85% were higher during the 6-minute walk test than during ADLs (P<.001). During the walk test, desaturation was detected in 27% of patients, but was not confirmed by ambulatory pulse oximetry during ADLs. In the subgroup of 11 patients using portable liquid oxygen no significant differences were found between SpO2 values recorded during the walk test and during ADLs with the appropriate oxygen flow. CONCLUSION: The 6-minute walk test is an effective method for detecting desaturation during ADLs and for establishing the oxygen flow needed to correct exercise-induced desaturation.

Eficacia de la prueba de los 6 minutos de marcha en la valoración de la oxigenoterapia de deambulación / Efficacy of the 6-minute walk test in evaluating ambulatory oxygen therapy

Objetivo: Comparar la saturación de la oxihemoglobina (SpO2) observada durante la prueba de los 6 min de marcha (P6m) con la SpO2 de la pulsioximetría ambulatoria realizada durante las actividades de la vida diaria (AVD). Se analizó también la eficacia de la P6m en determinar el flujo de oxígeno adecuado para prevenir la desaturación arterial durante las AVD. Pacientes y métodos: Se estudió a 37 pacientes diagnosticados de enfermedad pulmonar obstructiva crónica --valor medio (± desviación estándar) del volumen espiratorio forzado en el primer segundo 26 ± 9% del valor de referencia-- en los que se compararon los valores de SpO2 obtenidos en la P6m y la pulsioximetría ambulatoria. De los 20 pacientes con desaturación al esfuerzo, 11 aceptaron el oxígeno líquido portátil y realizaron la pulsioximetría ambulatoria de forma aleatorizada en 2 días consecutivos con y sin la administración de oxígeno. El flujo de oxígeno se estableció en la P6m con pruebas sucesivas hasta lograr una SpO2 media superior al 85%. Resultados: La SpO2 media en el total de pacientes fue del 84 ± 7% en la P6m y del 89 ± 4% en la pulsioximetría ambulatoria (p < 0,001). Los porcentajes de tiempo acumulado con SpO2 < del 90, del 88 y del 85% fueron superiores en la P6m (p < 0,001). Durante la P6m, en un 27% de los pacientes se detectó desaturación, que no se confirmó con la pulsioximetría ambulatoria. En el subgrupo de 11 pacientes no se observaron diferencias significativas entre la P6m y la pulsioximetría ambulatoria realizadas con el flujo de oxígeno ajustado. Conclusión: La P6m es un método eficaz para detectar la desaturación durante las AVD y establecer el flujo de oxígeno para corregir la desaturación al esfuerzo

Objective: To compare oxyhemoglobin saturation (SpO2) observed during the 6-minute walk test with that of pulse oximetry carried out during activities of daily living (ADLs). The efficacy of the 6-minute walk test for determining adequate oxygen flow to prevent arterial desaturation during ADLs was also analyzed. Patients and methods: We studied 37 patients diagnosed with chronic obstructive pulmonary disease (COPD)--mean (SD) forced expiratory volume in 1 second, 26% (9%) of predicted--and compared SpO2 values obtained in the 6-minute walk test with those obtained with ambulatory pulse oximetry during ADLs. Eleven of the 20 patients with exercise-induced desaturation agreed to use portable liquid oxygen and were randomized to ambulatory pulse oximetry on 2 consecutive days, both with and without the administration of oxygen. Oxygen flow was adjusted on successive 6-minute walk tests until a mean SpO2 greater than 85% was reached. Results: The mean SpO2 for all patients was 84% (7%) during the 6-minute walk test and 89% (4%) during ADLs (P<.001). Cumulative percentages of time with SpO2 less than 90%, 88%, and 85% were higher during the 6-minute walk test than during ADLs (P<.001). During the walk test, desaturation was detected in 27% of patients, but was not confirmed by ambulatory pulse oximetry during ADLs. In the subgroup of 11 patients using portable liquid oxygen no significant differences were found between SpO2 values recorded during the walk test and during ADLs with the appropriate oxygen flow. Conclusion: The 6-minute walk test is an effective method for detecting desaturation during ADLs and for establishing the oxygen flow needed to correct exercise-induced desaturation

[Acute confusional syndrome associated with obstructive sleep apnea aggravated by acidosis secondary to oral acetazolamide treatment]. / Síndrome confusional agudo asociado a apnea-hipopnea obstructiva del sueño y agravado por acidosis metabólica secundaria a acetazolamida oral.

Acute confusional syndrome, or delirium, is a transitory mental state characterized by the fluctuating alteration of awareness and attention levels. We present the case of a patient with acute confusional syndrome associated with obstructive sleep apnea syndrome (OSAS) aggravated by metabolic acidosis induced by oral acetazolamide treatment.A 70-year-old man with no history of neurological disease was referred with a clinical picture consistent with acute confusional syndrome presenting between midnight and dawn. During the admission examination infectious, toxic, and neurologic causes, or those related to metabolic or heart disease were ruled out. Arterial blood gases measured during one of the nighttime episodes of acute confusional syndrome showed mild hypoxia and hypercapnia with mixed acidosis. Signs and symptoms suggestive of OSAS had been developing over the months prior to admission, with snoring, sleep apnea, and moderate daytime drowsiness. Polysomnography demonstrated severe OSAS with an apnea-hypopnea index of 38. Mean arterial oxygen saturation was 83%; time oxygen saturation remained below 90% was 44%. The attending physician ordered the withdrawal of oral acetazolamide, which was considered the cause of the metabolic component of acidosis. Treatment with continuous positive airway pressure was initiated at 9 cm H2O, after a titration polysomnographic study. The patient continued to improve.OSAS, for which very effective treatment is available, should be included among diseases that may trigger acute confusional syndrome.

Rehabilitación en pacientes con enfermedades neuromusculares y con deformidades de la caja torácica / Rehabilitation in patients with neuromuscular and chest wall diseases

No disponbile (AU)

Errores en la administración de medicamentos por vía oral en dos centros sociosanitarios / Errors in the oral administration of medicines in two health centres

Objetivo: Conocer cómo se administran los medicamentos, detectar si se producen interacciones con los alimentos y qué tipo de errores se cometen con más frecuencia. Métodos: Se realizó un estudio descriptivo en dos centros sociosanitarios, en el que se evaluó si los medicamentos por vía oral se administraban correctamente. Se utilizó la información de las fichas técnicas y/o de los prospectos de los medicamentos. Resultados: Se evaluó la medicación administrada en un día, a 40 pacientes, en dos hospitales. Se administraron 274 y 238 medicamentos, respectivamente en los hospitales A y B, correspondientes a 344 y 330 dosis por vía oral. En el hospital A se cometieron 138 (23,4 por ciento) errores y se detectaron 65 posibles equivocaciones, que se desconoce si se llegaron a producir ya que no sabemos si la medicación se tomó correctamente. En el hospital B se cometieron 95 (25,0 por ciento) errores. No se observaron otros posibles errores. Los errores cometidos con más frecuencia fueron: no disolver o diluir la medicación en agua, administrar el medicamento con leche y/o antiácidos, dar la medicación con alimentos en vez de con el estómago vacío, no advertir al paciente de tragar el medicamento sin masticar. Otras equivocaciones fueron las referentes a la administración de la medicación con relación a las comidas. Discusión: Muchos de los errores que se cometen al administrar los medicamentos son debidos a una falta de conocimientos sobre su correcta utilización o a una deficiente difusión de la información (AU)

[Errors in the oral administration of medicines in two health centres] / Errores en la administración de medicamentos por vía oral en dos centros sociosanitarios.

OBJECTIVE: To know how medicines should be administered, to detect if there are any interaction whith food and the most frequent errors. METHOD: A descriptive study has been carried out in two health centres where we have evaluated if the oral medicines have been correctly dispensed. So as to do this, the summary of medicines' characteristics and/or medicine prospects were used. RESULTS: The daily administered medication for 40 patients was evaluated during one day in two different hospitals. We administered 274 medicines in hospital A and 238 medicines in hospital B wich correspond to 344 and 330 oral dosis. In hospital A 138 (23,4%) mistakes were made and another 65 potential errors were detected. It is unsure if these potential errors were made or not as we do not know if the medication was taken correctly by the patient. In hospital B 95 (25,0%) errors were committed. No other possible errors were observed. The most frequent errors that have been commited are: not to dilute the medication with water, to administer the medicine with milk and/or antiacid medicine, to take medicine with meals instead of taking them in abstinence. Not warning the pacient to swallow medicines without chewing them. Other errors were concerning the relationship between medication and meals. DISCUSSION: Many of the mistakes that are made when taking medicines are due to the lack of knowledge of the correct usage or lack of information.

International approaches to the prescription of long-term oxygen therapy.

While there is broad agreement about who should receive long-term oxygen therapy (LTOT), there is little information available on how clinicians should decide on the oxygen prescription itself, at rest, during sleep and during exercise. The authors describe the results of an international survey that was undertaken to compare how respirologists prescribed oxygen. A questionnaire was sent to 100 respirologists in each of seven countries. The questionnaire identified whether resting flow rates were derived in a standard manner or by individualized patient testing. Test targets were ascertained for rest, exercise and sleep, as was the percentage of time that each test target had to reach for the test to be accepted. The majority of respondents individualized the oxygen prescription at rest (81%). Resting arterial oxygen saturation (Sa,O2) was most commonly targeted at 90-91%. The approach to night prescription varied (p<0.001). Respirologists in Canada and the USA increased the resting Sa,O2 by 1-2 L x min(-1) during sleep, while those in Spain used the resting (awake) flow for the night prescription (62%). Respirologists in the Netherlands, France, and Italy individualized the night prescription more frequently. Although oxygen during exercise was individualized in most countries (74%), significant differences remained among countries (p<0.001). The majority of respirologists (62%) aimed to achieve an Sa,O2 of 90-91% during exercise, while 70% of all respirologists tried to achieve the desired Sa,O2 for 90% of the test. There were substantial differences among countries as to how the oxygen prescription was written. This survey highlights the need for multicentre studies that improve the effectiveness of long-term oxygen therapy utilization.

Long-term effects of outpatient rehabilitation of COPD: A randomized trial.

OBJECTIVE: To examine the short- and long-term effects of an outpatient pulmonary rehabilitation program for COPD patients on dyspnea, exercise, health-related quality of life, and hospitalization rate. SETTING: Secondary-care respiratory clinic in Barcelona. METHODS: We conducted a randomized controlled trial with blinding of outcome assessment and follow-up at 3, 6, 9, 12, 18, and 24 months. Sixty patients with moderate to severe COPD (age 65 +/- 7 years; FEV(1) 35 +/- 14%) were recruited. Thirty patients randomized to rehabilitation received 3 months of outpatient breathing retraining and chest physiotherapy, 3 months of daily supervised exercise, and 6 months of weekly supervised breathing exercises. Thirty patients randomized to the control group received standard care. RESULTS: We found significant differences between groups in perception of dyspnea (p < 0.0001), in 6-min walking test distance (p < 0.0001), and in day-to-day dyspnea, fatigue, and emotional function measured by the Chronic Respiratory Questionnaire (p < 0. 01). The improvements were evident at the third month and continued with somewhat diminished magnitude in the second year of follow-up. The PR group experienced a significant (p < 0.0001) reduction in exacerbations, but not the number of hospitalizations. The number of patients needed to treat to achieve significant benefit in health-related quality of life for a 2-year period was approximately three. CONCLUSION: Outpatient rehabilitation programs can achieve worthwhile benefits that persist for a period of 2 years.

Predicting the result of noninvasive ventilation in severe acute exacerbations of patients with chronic airflow limitation.

OBJECTIVE: To analyze prospectively the factors related to the success of noninvasive ventilation (NIV) in the treatment of acute exacerbations of chronic airflow limitation (CAFL) and to generate a multiple regression model in order to detect which patients can be successfully treated by this method. SETTING: A respiratory medicine ward of a referral hospital. METHODS AND PRINCIPAL RESULTS: Initially, we examined 44 episodes of acute respiratory failure in 36 patients with CAFL in whom mechanical ventilation was advisable. In 34 of 44 episodes (77%), NIV was used successfully. Patients in whom NIV succeeded had a lower FEV(1) prior to admission, a higher level of consciousness (LC), and significant improvements in PaCO(2), pH, and LC after 1 h of NIV. A logistic regression model consisting of baseline FEV(1) and PaCO(2) values, initial PaCO(2), pH, and LC values on admission, and PaCO(2) values after 1 h of NIV allowed us to correctly classify > 95% of the 44 episodes in which the outcome was successful. In the second part of the study, we prospectively validated the equation in another 15 consecutive CAFL patients with acute hypercapnic respiratory failure. NIV successfully treated 12 patients (80%), and the model correctly classified 14 patients (93%). CONCLUSION: Good LC at the beginning of NIV and improvements in pH, PaCO(2), and LC values after 1 h of NIV are associated with successful responses to NIV in COPD patients with acute hypercapnic respiratory failure. Our validated multiple regression model confirms that these variables predict the result of NIV in acute hypercapnic failure in CAFL patients.

[Neuro-cognitive condition of 8 year old children with congenital hypothyroidism treated early]. / Estado neurocognitivo en niños de 8 años con hipotiroidismo congénito tratado precozmente.

INTRODUCTION: Congenital hypothyroidism is the most important cause of preventable mental retardation. Since the use of programmes for early detection, mental retardation due to cretinism has been abolished and current investigations seek to detect subtle damage due to foetal hypothyroidism and strategies to minimize such deficits. OBJECTIVE: This study presents the results of neurocognitive assessment of a group of 19 children aged 8 in the Cuban Programme for the early detection of Congenital Hypothyroidism. PATIENTS AND METHODS: The programme is based on the use of umbilical cord serum levels of thyrotropin (TSH), using the Elisa ultramicro method (SUMA) and substitutive treatment with sodium levothyroxine and a programme of neuropsychiatric stimulation until 5 years old. RESULTS: The results showed that the intelligence quotients of children with hypothyroidism were not statistically different from paired controls, and thus demonstrate the efficacy of the programme. On evaluation using computerized techniques for the detection of subtle disorders of the maintenance of attention, deficiencies were found. Analysis of the conventional EEG showed that in 13 cases recordings were normal, 4 had generalized cortical damage, 1 had cortico-subcortical damage and the remainder had signs of focal irritation. On the quantitative EEG, correlation between the attention variables and absolute values (MV2/Hz) were calculated for each derivation and associations found mainly in the right parietal and left frontal regions. CONCLUSION: The effect of stimulating development in these patients is discussed.

Quality of life in patients with chronic respiratory disease: the Spanish version of the Chronic Respiratory Questionnaire (CRQ)

The aim of this study was to translate the Chronic Respiratory Questionnaire (CRQ) into Spanish and to test its measurement properties. The study was performed in 60 patients with chronic obstructive pulmonary disease (forced expiratory volume in one second (FEV1) mean+/-SD 35+/-14% of reference value). A rigorous process of forward and back translation and review produced an easily comprehensible questionnaire, which was administered together with measures of pulmonary function and exercise capacity. The patients were randomly allocated to one of two groups: 30 received respiratory rehabilitation and the other 30 received standard community care only. Weak to moderate statistically significant correlations (0.2-0.38) were found between the domains of the CRQ and pulmonary function and exercise measures. For the three CRQ domains that measure differences between patients at a point in time, Crohnbach's alpha and intraclass correlation coefficients were: fatigue 0.80 and 0.80; emotional function 0.86 and 0.68; and mastery domains 0.84 and 0.67, respectively. Scores remained stable in patients who were deemed clinically stable, and showed large statistically significant improvement (p<0.0001) in patients in the rehabilitation programme. Only low correlations were found between the changes in CRQ and the changes in pulmonary function and exercise capacity. The index of responsiveness was 0.92 for fatigue, and 0.91 for dyspnoea, emotional function and mastery. In conclusion, the Spanish translation of the Chronic Respiratory Questionnaire is likely to be useful for measuring differences between patients, and particularly for measuring the effects of intervention on quality of life in chronic respiratory disease.

[Better at home: a continuous health care program for patients with advanced chronic respiratory disease]. / Mejor en casa: un programa de asistencia continuada para los pacientes con enfermedad respiratoria crónica avanzada.

The objective of this study was to analyze the effect of continuous health care on the frequency of readmissions of patients with advanced chronic respiratory disease. The study was prospective, enrolling 26 patients (16 with COPD, 7 with bronchiectasis and 3 with pachypleuritis) who had been admitted at least 3 times within the past year. The patients were assigned to 3 groups: group A was the ambulatory monitoring group, with 8 patients who were able to travel to the hospital for monthly outpatient checkups; group B was the ambulatory pulmonary rehabilitation group, with 10 patients who were able to travel to the hospital and who needed rebreathing training (one weekly group session); and group C was the home care group, with 8 patients who were unable to travel to the hospital and who received weekly or biweekly house calls. All patients had telephone contact with the program team. Mean lung function values for the whole population were FVC 40 (11)%, FEV1 23 (7)% of reference, PaO2 55 (7) and PaCO2 55 (10) mmHg. A significant decrease in number of admissions (79 versus 18, p < 0.0001) was observed in both the first and second halves of the year in all three treatment groups: A, 25 to 2; B, 28 to 8; and C, 26 to 8 (p < 0.001). The reduction in health care costs over the previous year's expenditure was calculated to be 22,751,402 pesetas. We conclude that specialized health care that is continuous and personalized reduces the number of hospital readmissions of patients with advanced chronic respiratory disease. Moreover, the overall cost of care, without the need to make house calls to all patients.