Effects of noninvasive positive pressure ventilatory support in non-COPD patients with acute respiratory insufficiency after early extubation

Objective: To investigate the effects of noninvasive positive pressure ventilation (NPPV) on pulmonary gas exchange, breathing pattern, intrapulmonary shunt fraction, oxygen consumption, and resting energy expenditure in patients with persistent acute respiratory failure but without chronic obstructive pulmonary disease (COPD) after early extubation. Design: Prospective study. Setting: Multidisciplinary intensive care unit of a university hospital. Patients: 15 patients after prolonged mechanical ventilation (> 72 h) with acute respiratory insufficiency after early extubation. Interventions: Criteria for early extubation were arterial oxygen tension (PaO₂) L 40 mm Hg (fractional inspired oxygen 0.21), arterial carbon dioxide tension (PaCO₂) K 55 mm Hg, pH > 7.32, respiratory rate K 40 breaths per min, tidal volume (V_T) L 3 ml/kg, rapid shallow breathing index K 190 and negative inspiratory force L 20 cmH₂O. After extubation, two modes of NPPV were applied [continuous positive airway pressure (CPAP) of 5 cmH₂O and pressure support ventilation (PSV) with 15 cmH₂O pressure support]. Measurements and main results: Oxygenation and ventilatory parameters improved during both modes of NPPV (p < 0.05): increase in PaO₂ of 11 mm Hg during CPAP and 21 mm Hg during PSV; decrease in intrapulmonary shunt fraction of 7 % during CPAP and 12 % during PSV; increase in tidal volume of 1 ml/kg during CPAP and 4 ml/kg during PSV; decrease in respiratory rate 6 breaths/min during CPAP and 9 breaths/min during PSV. Oxygen consumption (15 % during CPAP, 22 % during PSV) and resting energy expenditure (12 % during CPAP, 20 % during PSV) were reduced (p < 0.05). PaCO₂ decreased, whereas minute ventilation and pH increased during PSV (p < 0.05). The median duration of NPPV was 2 days. Two patients had to be reintubated. Conclusions: In non-COPD patients with persistent acute respiratory failure after early extubation, NPPV improved pulmonary gas exchange and breathing pattern, decreased intrapulmonary shunt fraction, and reduced the work of breathing. Received: 14 May 1999 Final revision received: 25 June 1999 Accepted: 6 July 1999     

Ventilatory assist therapy

NPPV has been shown to improve arterial blood gas values, prevent symptoms resulting from alveolar hypoventilation, and decrease hospitalization in patients with chronic respiratory failure with COPD. Regarding acute exacerbation of COPD, the utility of NPPV has been established so NPPV will be regarded first-line therapy as ventilatory assist therapy. On the other hand, with respect to chronic stable COPD, the utility of NPPV isn' t established yet. However NPPV cases have been increasing rapidly in these years, as new home respiratory care technique. From now on, we have to evaluate the objective utility of NPPV from the standpoint of evidence.     

Physiological effects of noninvasive positive ventilation during acute moderate hypercapnic respiratory insufficiency in children

Introduction  A prospective physiological study was performed in 12 paediatric patients with acute moderate hypercapnic respiratory insufficiency to assess the ability of noninvasive positive pressure ventilation (NPPV) to unload the respiratory muscles and improve gas exchange. Materials and methods  Breathing pattern, gas exchange, and inspiratory muscle effort were measured during spontaneous breathing and NPPV. Results  NPPV was associated with a significant improvement in breathing pattern, gas exchange and respiratory muscle output. Tidal volume and minute ventilation increased by 33 and 17%, and oesophageal and diaphragmatic pressure time product decreased by 49 and 56%, respectively. This improvement in alveolar ventilation translated into a reduction in mean partial pressure in carbon dioxide from 48 to 40 mmHg (P = 0.01) and in respiratory rate from 48 to 41 breaths/min (P = 0.01). No difference between a clinical setting and a physiological setting of NPPV was observed. In conclusion, this study shows that NPPV is able to unload the respiratory muscles and improve clinical outcome in young patients admitted to the paediatric intensive care unit for acute moderate hypercapnic respiratory insufficiency. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Iron lung versus mask ventilation in acute exacerbation of COPD: a randomised crossover study

Objective  To compare iron lung (ILV) versus mask ventilation (NPPV) in the treatment of COPD patients with acute on chronic respiratory failure (ACRF). Design  Randomised multicentre study. Setting  Respiratory intermediate intensive care units very skilled in ILV. Patients and methods  A total of 141 patients met the inclusion criteria and were assigned: 70 to ILV and 71 to NPPV. To establish the failure of the technique employed as first line major and minor criteria for endotracheal intubation (EI) were used. With major criteria EI was promptly established. With at least two minor criteria patients were shifted from one technique to the other. Results  On admission, PaO₂/FiO₂, 198 (70) and 187 (64), PaCO₂, 90.5 (14.1) and 88.7 (13.5) mmHg, and pH 7.25 (0.04) and 7.25 (0.05), were similar for ILV and NPPV groups. When used as first line, the success of ILV (87%) was significantly greater (P = 0.01) than NPPV (68%), due to the number of patients that met minor criteria for EI; after the shift of the techniques; however, the need of EI and hospital mortality was similar in both groups. The total rate of success using both techniques increased from 77.3 to 87.9% (P = 0.028). Conclusions  The sequential use of NPPV and ILV avoided EI in a large percentage of COPD patients with ACRF; ILV was more effective than NPPV on the basis of minor criteria for EI but after the crossover the need of EI on the basis of major criteria and mortality was similar in both groups of patients.     

Respiratory pattern during neurally adjusted ventilatory assist in acute respiratory failure patients

Purpose  

To investigate the effect of a wide range of assistance levels during neurally adjusted ventilatory assist (NAVA) and pressure support ventilation (PSV) on respiratory pattern, breathing variability, and incidence of tidal volumes (V _T) above 8 and 10 ml/kg in acute respiratory failure patients.     

Neurally adjusted ventilatory assist in patients with critical illness-associated polyneuromyopathy

Purpose  

Diaphragmatic electrical activity (EA_di), reflecting respiratory drive, and its feedback control might be impaired in critical illness-associated polyneuromyopathy (CIPM). We aimed to evaluate whether titration and prolonged application of neurally adjusted ventilatory assist (NAVA), which delivers pressure (P _aw) in proportion to EA_di, is feasible in CIPM patients.     

Respiratory muscle strength and muscle endurance are not affected by acute metabolic acidemia

Respiratory muscle fatigue in asthma and chronic obstructive lung disease (COPD) contributes to respiratory failure with hypercapnia, and subsequent respiratory acidosis. Therapeutic induction of acute metabolic acidosis further increases the respiratory drive and, therefore, may diminish ventilatory failure and hypercapnia. On the other hand, it is known that acute metabolic acidosis can also negatively affect (respiratory) muscle function and, therefore, could lead to a deterioration of respiratory failure. Moreover, we reasoned that the impact of metabolic acidosis on respiratory muscle strength and respiratory muscle endurance could be more pronounced in COPD patients as compared to asthma patients and healthy subjects, due to already impaired respiratory muscle function. In this study, the effect of metabolic acidosis was studied on peripheral muscle strength, peripheral muscle endurance, airway resistance, and on arterial carbon dioxide tension (PaCO₂). Acute metabolic acidosis was induced by administration of ammonium chloride (NH₄Cl). The effect of metabolic acidosis was studied on inspiratory and expiratory muscle strength and on respiratory muscle endurance. Effects were studied in a randomized, placebo‐controlled cross‐over design in 15 healthy subjects (4 male; age 33·2 ± 11·5 years; FEV₁ 108·3 ± 16·2% predicted), 14 asthma patients (5 male; age 48·1 ± 16·1 years; FEV₁ 101·6 ± 15·3% predicted), and 15 moderate to severe COPD patients (9 male; age 62·8 ± 6·8 years; FEV₁ 50·0 ± 11·8% predicted). An acute metabolic acidemia of BE –3·1 mmol.L^?1 was induced. Acute metabolic acidemia did not significantly affect strength or endurance of respiratory and peripheral muscles, respectively. In all subjects airway resistance was significantly decreased after induction of metabolic acidemia (mean difference –0·1 kPa.sec.L^?1 [95%‐CI: ?0·1 –?0·02]. In COPD patients PaCO₂ was significantly lowered during metabolic acidemia (mean difference –1·73 mmHg [?3·0 –?0·08]. In healthy subjects and in asthma patients no such effect was found. Acute metabolic acidemia did not significantly decrease respiratory or peripheral muscle strength, respectively muscle endurance in nomal subjects, asthma, or COPD patients. Metabolic acidemia significantly decreased airway resistance in asthma and COPD patients, as well as in healthy subjects. Moreover, acute metabolic acidemia slightly improved blood gas values in COPD patients. The results suggest that stimulation of ventilation in respiratory failure, by induction of metabolic acidemia will not lead to deterioration of the respiratory failure.     

Non-invasive positive pressure ventilation in acute respiratory failure: providing competent care

Non-invasive positive pressure ventilation (NPPV) has been used as an alternative strategy to provide ventilatory support for patients with acute respiratory failure. Most studies demonstrate that the use of NPPV in acute respiratory failure results in a reduction in the need for endotracheal intubation and an overall survival advantage. However, current evidence, in the form of randomized controlled trials, suggests that these benefits may be restricted to patients suffering from acute exacerbation of chronic obstructive pulmonary disease (COPD).

The clinical application of NPPV involves the development of competence in delivering the particular intervention. Clinical outcomes and thus valid comparisons with alternate methods of ventilatory support can only be made if attention is paid to the clinical indications for the application of NPPV and patient subgroups it is used to treat and the level of competence of care givers in its application and delivery. One essential element of competence is the establishment of an appropriate knowledge base and the development of clinical practice guidelines. This literature review identifies the current indications for NPPV and the relevant information for developing clinical practice guidelines for the management of this form of ventilatory support.     

Noninvasive positive pressure ventilation reverses acute respiratory failure in select "do-not-intubate" patients

OBJECTIVE: To determine the outcome from the use of noninvasive positive pressure ventilation (NPPV) in "do-not-intubate" (DNI) patients in acute respiratory failure. DESIGN: Prospective observational study. SETTING: University-affiliated large medical center. PATIENTS: All patients with DNI status who received NPPV for a 1-yr period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic, physiologic, and laboratory data were collected before initiation, 2 hrs after initiation, and each morning and evening for as long as NPPV was provided. Data were recorded on 137 episodes of acute respiratory failure in 131 DNI patients. Hospital mortality rate was 37.5% in 24 patients with an exacerbation of chronic obstructive pulmonary disease (COPD), 39% in 28 patients with acute cardiogenic pulmonary edema, 68% in nine patients with non-COPD hypercapnic ventilatory failure, 77% in 13 post-extubation respiratory failure patients, and 86% in 57 patients with hypoxemic respiratory failure. Advanced cancer was present in 40 patients and was associated with increased risk of death (85% mortality rate, p = .002). A score based on the Simplified Acute Physiology Score (SAPS) II and serum albumin level calculated before NPPV was predictive of hospital outcome. CONCLUSIONS: NPPV is successful in reversing acute respiratory failure and preventing hospital mortality in DNI patients with COPD and cardiogenic pulmonary edema but not in patients with post-extubation failure, hypoxemic respiratory failure, or end-stage cancer. An easy-to-calculate score combining SAPS II and serum albumin level is a good prediction of outcome in DNI patients receiving NPPV.     

无创通气在机械通气撤离中的作用

目的 探讨无创通气(Noninvasive positive pressure Ventilation,NNPV)在多种原因导致的急性呼吸衰竭机械通气患者撤机流程中的有效性.方法 前瞻性分析2007年1月至2008年12月浙江大学医学院附属邵逸犬医院ICU人选的71例急性呼吸衰竭机械通气患者.经气管插管机械通气治疗48 h后,达到临床撤机条件,但末能完成自主呼吸试验,排除NPPV禁忌证,将患者随机(随机数字法)分成无创通气序贯撤机(NPPV组,n=36)和传统撤机方法(IPPV组,n=35)两组.NPPV组拔管前予提高压力支持水平休息30 min,拔管后立即给予NPPV作为撤机方法;IPPV组传统方法撤机.观察两组患者自主呼吸试验前后呼吸力学参数、动脉血气、循环指标的变化,以及分组后两组机械通气2 h后的心肺参数,同时比较两组患者的转归.结果 分绀后机械通气2 h后心肺参数差异无统计学意义.与IPPV组相比,NPPV组机械通气时间、ICU住院时间、总住院时间明显缩短,分别为[(14.88 ±3.76)d vs.(20.68±2.79)d,P<0.01);(14.16±3.45)d vs.(2.57±7.71)d,P<0.01);IPPV组分别为(23.39±5.19)d vs.(33.89±8.58)d,P<0.01)],NPPV组并发症发生率明显低于IPPV组(22.9%vs.72.2%,P<0.01),特别是肺部感染发生率较低(6.1%vs.36.1%,P<0.01).结论 NPPV适用于多种原因导致的呼吸衰竭的撤机过程.把握无创通气NPPV的适应证,以及在撤机过程中及早进行NPPV干预,可以提高NPPV住序贯撤机中的成功率.     

Non-invasive negative and positive pressure ventilation in the treatment of acute on chronic respiratory failure

Objective To investigate in clinical practice the role of non-invasive mechanical ventilation in the treatment of acute respiratory failure on chronic respiratory disorders.Design An 18 months prospective cohort study.Setting A specialised respiratory intensive care unit in a university-affiliated hospital.Patients A total of 258 consecutive patients with acute respiratory failure on chronic respiratory disorders.Interventions Criteria for starting non-invasive mechanical ventilation and for endotracheal intubation were predefined. Non-invasive mechanical ventilation was provided by positive pressure (NPPV) ventilators or iron lung (NPV).Results The main characteristics of patients (70% with chronic obstructive pulmonary disease) on admission were (mean, SD or median, 25th–75th centiles): pH 7.29 (0.07), PaCO₂ 83 mm Hg (19), PaO₂/FiO₂ 198 (77), APACHE II score 19 (15–24). Among the 258 patients, 200 (77%) were treated exclusively with non-invasive mechanical ventilation (40% with NPV, 23% with NPPV, and 14% with the sequential use of both), and 35 (14%) with invasive mechanical ventilation. In patients in whom NPV or NPPV failed, the sequential use of the alternative non-invasive ventilatory technique allowed a significant reduction in the failure of non-invasive mechanical ventilation (from 23.4 to 8.8%, p=0.002, and from 25.3 to 5%, p=0.0001, respectively). In patients as a whole, the hospital mortality (21%) was lower than that estimated by APACHE II score (28%).Conclusions Using NPV and NPPV it was possible in clinical practice to avoid endotracheal intubation in the large majority of unselected patients with acute respiratory failure on chronic respiratory disorders needing ventilatory support. The sequential use of both modalities may increase further the effectiveness of non-invasive mechanical ventilation.Electronic Supplementary Material Supplementary material is available in the online version of this article at http://dx.doi.org/10.1007/s00134-003-2145-9     

Long term oxygen therapy and mechanical ventilation for patients with COPD

Non-drug treatments such as long term oxygen therapy (LTOT) and non-invasive positive pressure ventilation (NPPV) are thought important for patients with chronic obstructive pulmonary disease (COPD). It is reported that LTOT can improve the prognosis of patients with COPD, particularly who have severe respiratory failure. NPPV attracted attention to avoid endotracheal intubation and high efficacy in patients with acute exacerbation of COPD. In chronic phase of COPD, NPPV may improve the quality of life in patients with hypercapnia, selected carefully.     

The evidence for noninvasive positive-pressure ventilation in the care of patients in acute respiratory failure: a systematic review of the literature

Noninvasive positive-pressure ventilation (NPPV) is increasingly being used in the care of patients suffering acute respiratory failure. High-level evidence supports the use of NPPV to treat exacerbation of chronic obstructive pulmonary disease (COPD). NPPV has also been successfully used with selected patients suffering acute hypoxemic respiratory failure and to allow earlier extubation of mechanically ventilated COPD patients. The evidence for NPPV for acute cardiogenic pulmonary edema is inconclusive. With selected patients NPPV decreases the rate of intubation, mortality, and nosocomial pneumonia. Predictors of NPPV failure include greater severity of illness, lower level of consciousness, lower pH, more air leak around the patient-mask interface, greater quantity of secretions, poor initial response to NPPV, and the presence of pneumonia. NPPV obviates intubation in > 50% of appropriately selected patients. Both nasal and oronasal interfaces have been successfully used to apply NPPV, but the oronasal interface is often preferred for acute respiratory failure. Any ventilator and ventilator mode can be used to apply NPPV, but portable pressure ventilators and pressure-support mode are most commonly used. Inhaled bronchodilators can be administered during NPPV, and NPPV can be delivered with helium-oxygen mixture. Institution-specific practice guidelines may be useful to improve NPPV success.     

Respiratory pattern of diaphragmatic breathing and pilates breathing in COPD subjects

BACKGROUND:

Diaphragmatic breathing (DB) is widely used in pulmonary rehabilitation (PR) of patients with chronic obstructive pulmonary disease (COPD), however it has been little studied in the scientific literature. The Pilates breathing (PB) method has also been used in the rehabilitation area and has been little studied in the scientific literature and in COPD.

OBJECTIVES:

To compare ventilatory parameters during DB and PB in COPD patients and healthy adults.

METHOD:

Fifteen COPD patients (COPD group) and fifteen healthy patients (healthy group) performed three types of respiration: natural breathing (NB), DB, and PB, with the respiratory pattern being analyzed by respiratory inductive plethysmography. The parameters of time, volume, and thoracoabdominal coordination were evaluated. After the Shapiro-Wilk normality test, ANOVA was applied followed by Tukey''s test (intragroup analysis) and Student''s t-test (intergroup analysis; p<0.05).

RESULTS:

DB promoted increase in respiratory volumes, times, and SpO₂ as well as decrease in respiratory rate in both groups. PB increased respiratory volumes in healthy group, with no additional benefits of respiratory pattern in the COPD group. With respect to thoracoabdominal coordination, both groups presented higher asynchrony during DB, with a greater increase in the healthy group.

CONCLUSIONS:

DB showed positive effects such as increase in lung volumes, respiratory motion, and SpO₂ and reduction in respiratory rate. Although there were no changes in volume and time measurements during PB in COPD, this breathing pattern increased volumes in the healthy subjects and increased oxygenation in both groups. In this context, the acute benefits of DB are emphasized as a supporting treatment in respiratory rehabilitation programs.     

Noninvasive positive pressure ventilation in patients with COPD]

There is sufficient clinical evidence to justify the use of long-term NPPV in selected patients with COPD who have daytime hypercapnia complicated by nocturnal hypoventilation that can be reversed with NPPV. In those patients, NPPV can improve their arterial blood gases and symptoms, reduce their hospital stay, and increase their QOL. In selected COPD patients with acute exacerbation, NPPV can decrease rates of tracheal intubation leading to reduced mortality. For maximal effectiveness, NPPV must be used early in the course of the respiratory failure (less severe levels of acidosis).     

Sequential use of noninvasive pressure support ventilation for acute exacerbations of COPD

Objectives: To compare the efficacy of noninvasive pressure support ventilation (NIPSV) in acute decompensation in chronic obstructive pulmonary disease (COPD) by means of a bi-level positive airway pressure support system (BiPAP) in a sequential mode with medical therapy alone; to assess the short-term physiologic effects of the device on gas exchange; and to compare patients successfully ventilated with NIPSV with those in whom NIPSV failed. Design: A prospective case series with historically matched control study. Setting: A general intensive care unit (ICU) of a university hospital. Patients: We evaluated the efficacy of administration of NIPSV in 42 COPD patients and compared this with standard treatment in 42 matched historical control COPD patients. Interventions: NIPSV was performed in a sequential mode, i. e., BiPAP in the spontaneous mode was used for at least 30 min every 3 h. Between periods of ventilation, patients could be systematically returned to BiPAP when the arterial oxygen saturation was < 0.85 or when the respiratory rate was > 30 breaths/min. Measurements and results: Success rate, mortality, duration of ventilatory assistance, and length of ICU stay were recorded. Eleven of the 42 patients (26 %) in the NIPSV group needed tracheal intubation compared with 30 of the 42 control patients (71 %). The 31 patients in whom NIPSV was successful were ventilated for a mean of 6 ± 3 days. In-hospital mortality was not significantly different in the treated versus the control group, but the duration of ventilatory assistance (7 ± 4 days vs 15 ± 10 days, p < 0.01) and the length of ICU stay (9 ± 4 days vs 21 ± 12, p < 0.01) were both shortened by NIPSV. BiPAP was effective in correcting gas exchange abnormalities. The pH values, measured after 45 min of BiPAP with optimal settings, in the success (7.38 ± 0.04) and failure (7.28 ± 0.04) patients were significantly different (p < 0.05). Conclusions: NIPSV, performed with a sequential mode, may be used in the management of patients with acute exacerbations of COPD. Received: 10 February 1997 Accepted: 14 July 1997     

Breathing pattern and additional work of breathing in spontaneously breathing patients with different ventilatory demands during inspiratory pressure support and automatic tube compensation

Objective: We designed a new ventilatory mode to support spontaneously breathing, intubated patients and to improve weaning from mechanical ventilation. This mode, named Automatic Tube Compensation (ATC), compensates for the flow-dependent pressure drop across the endotracheal tube (ETT) and controls tracheal pressure to a constant value. In this study, we compared ATC with conventional patient-triggered inspiratory pressure support (IPS). Design: A prospective, interventional study. Setting: A medical intensive care unit (ICU) and an ICU for heart and thoracic surgery in a university hospital. Patients: We investigated two groups of intubated, spontaneously breathing patients: ten postoperative patients without lung injury, who had a normal minute ventilation (V_E) of 7.6 ± 1.7 l/min, and six critically ill patients who showed increased ventilatory demand (V_E = 16.8 ± 3.0 l/min). Interventions: We measured the breathing pattern [V_E, tidal volume (V_T), and respiratory rate (RR)] and additional work of breathing (WOB_add) due to ETT resistance and demand valve resistance. Measurements were performed under IPS of 5, 10, and 15 mbar and under ATC. Results: The response of V_T, RR, and WOB_add to different ventilatory modes was different in both patient groups, whereas V_E remained unchanged. In postoperative patients, ATC, IPS of 10 mbar, and IPS of 15 mbar were sufficient to compensate for WOB_add. In contrast, WOB_add under IPS was greatly increased in patients with increased ventilatory demand, and only ATC was able to compensate for WOB_add. Conclusions: The breathing pattern response to IPS and ATC is different in patients with differing ventilatory demand. ATC, in contrast to IPS, is a suitable mode to compensate for WOB_add in patients with increased ventilatory demand. When WOB_add was avoided using ATC, the patients did not need additional pressure support. Received: 24 April 1996 Accepted: 17 February 1997     

Clinical evaluation of diminished early expiratory flow (DEEF) ventilation in mechanically ventilated COPD patients

Objective To evaluate the cardiopulmonary effects, especially the end-expiratory lung volume (EEV) and ventilation inhomogeneity during diminished early expiratory flow ventilation (DEEF), which resembles pursed-lips breathing, with the conventional intermitent positive pressure ventilation (IPPV) in postoperative mechanically ventilated patients with chronic obstructive pulmonary disease (COPD).Design A prospective study measuring cardiopulmonary parameters during IPPV, DEEF, and positive end-expiratory pressure (PEEP) as a control mode. In the PEEP mode, PEEP values were chosen such that the mean airway pressure during a breath cycle was equal to that during the DEEF mode, which was higher than the conventional IPPV mode.Setting Surgical intensive care unit of a university hospital.Patients 20 postoperative mechanically ventilated COPD patients who were optimally pretreated and had normal blood oxygenation.Interventions Measurements were started in the IPPV (IPPV₁) mode, continued in a randomized order with DEEF or PEEP, and completed with a second IPPV (IPPV₂) mode, with 1 h equilibration time in each mode before each measurement.Measurements and results A multi-breath indicator gas wash-out test was used to calculate the EEV and ventilation inhomogeneity. There was a 9% increase (p<0.05) in the mean EEV during both the DEEF and PEEP mode compared to IPPV. No significant changes in the ventilation inhomogeneity and deadspace fractions or the hemodynamic parameters were found during the different ventilatory modes.Conclusions There was no improvement in pulmonary and hemodynamic parameters during the DEEF mode in comparison to the IPPV mode. The small increase in EEV during DEEF was probably caused by the slightly higher mean expiratory pressures as in the PEEP mode. However, this had no effect on the hemodynamic parameters. As we could not observe any improvement with the DEEF ventilation in our optimally pretreated postoperative COPD patients, we do not advise applying this therapy in this group of patients, since this mode of ventilation may cause barotrauma if not monitored adequately.     

Nitrite in exhaled breath condensate as a marker of nitrossative stress in the airways of patients with asthma,COPD, and idiopathic pulmonary fibrosis

Background: Nitrite and nitrate are exhaled in droplets of an aerosol during breathing and can be assayed in the exhaled breath condensate (EBC) as markers of nitrossative stress in the airways of patients with asthma, COPD, and idiopathic pulmonary fibrosis (IPF). Subjects and methods: Using HPLC with fluorescence detection, nitrite and nitrate were assayed in EBC of 14 atopic patients with mild‐to‐moderate stable asthma, 18 atopic asthmatics with exacerbation, 14 COPD patients without exacerbation, 18 patients with exacerbated COPD, 13 patients with active IPF, and in 29 healthy subjects. Results: The geometric mean [exp(mean±SD)] EBC concentrations of nitrite (micromol/l) in patients with asthma [5.1(2.1–12.3)], exacerbation of asthma [5.1(2.8–9.6)], exacerbation of COPD [5.3(3.2–8.7)], and with IPF [5.5(2.9–10.2)] were higher (P<0.05) compared with those of healthy subjects [2.9(1.6–5.3)] and patients with stable COPD [3.0(1.3–6.7)]. Nitrite concentration increased with decreased lung function of patients with asthma (r_s=?0.31, P<0.02). Presumably owing to the contamination of the EBC sample with nitrate during collection, nitrate levels were highly variable among healthy subjects and higher compared with all groups of patients. Conclusion: EBC nitrite is a suitable marker of nitrossative stress in adult patients with lung diseases but cannot differentiate controlled and exacerbated asthma. Further improvements to the methods of EBC collection and sample handling are warranted. J. Clin. Lab. Anal. 24:317–322, 2010. © 2010 Wiley‐Liss, Inc.     

Effectiveness of non-invasive positive pressure ventilation differs between decompensated chronic restrictive and obstructive pulmonary disease patients

OBJECTIVE: To compare the efficiency of non-invasive positive pressure ventilation (NPPV) in decompensated patients with either chronic obstructive pulmonary disease (COPD) or chronic restrictive pulmonary disease. DESIGN: Retrospective study. SETTING: A 17-bed intensive care unit in a university teaching hospital. SETTING: Sixty-four patients with COPD (age: 70+/-13 years, sex ratio: 37 male to 27 female patients, forced expiratory volume in 1 s: 31+/-13% predicted) and 20 patients with chronic restrictive pulmonary disease (age: 75+/-9 years, sex ratio: 9 male to 11 female patients, total lung capacity: 57+/-17% predicted) consecutively treated with NPPV (facial mask, pressure support ventilation (PSV) +/- PEEP) for acute respiratory failure. MEASUREMENTS AND RESULTS: There were no statistically significant differences between COPD and patients with chronic restrictive pulmonary disease in terms of cause of exacerbation, use of oxygen therapy or NPPV at home, severity of acute respiratory failure (ARF), mean delay from intensive care admission to initiation of NPPV and total duration of NPPV. Patients with chronic restrictive pulmonary disease had a lower success rate on NPPV (without need of tracheal intubation) than COPD (35% vs 67%, p=0.01). Causes of NPPV failure were not different between COPD and patients with restrictive disease. After 12 h of NPPV, restrictive patients who succeeded with NPPV had similar respiratory rate, minute ventilation and arterial blood gas to COPD patients. At the 3rd and 12th h of NPPV, improvements in pH and PaCO(2) were predictive of NPPV success in COPD, but not in restrictive patients. CONCLUSION: The results of this retrospective study suggest that the effectiveness of NPPV for acute decompensation is less in patients with chronic restrictive pulmonary disease as compared to COPD.