Use Of Noninvasive Mechanical Ventilation Research Articles

Pneumonia in a Cardiothoracic Intensive Care Unit: Incidence and Risk Factors

The purpose of this study was to determine the incidence, risk factors, and pathogens causing pneumonia in a cardiothoracic intensive care unit (CTICU). A prospective study. "Civili Hospital," Brescia, Italy. One hundred forty consecutive patients in the CTICU for more than 24 hours from October 1, 2006, to September 30, 2007. None. Demographic variables and intrinsic and extrinsic risk factors were analyzed with univariate and multivariate analysis. One hundred forty patients were studied, 128 (91.4%) were surgical and 12 (8.5%) were medical. Cumulative incidence of pneumonia was 28.6% (n = 40); 62.5% (n = 25) had ventilator-associated pneumonia (VAP) and 37.5% (n = 15) had non-VAP. The most common isolated pathogens were Pseudomonas aeruginosa (n = 15), Staphylococcus aureus (n = 5), Escherichia coli (n = 4), and Klebsiella pneumoniae (n = 3). Mortality was 22.2% (n = 31), with 54.8% (n = 17) of patients with pneumonia leading to mortality during CTICU stay (p = 0.0006). On multivariate analysis, independent risk factors for pneumonia were each point of the Sequential Organ Failure Assessment score at CTICU admission (p = 0.006, odds ratio [OR] = 1.39, confidence interval [CI] = 1.09-1.76), every day of mechanical ventilation (p = 0.049, OR = 1.08, CI = 1.00-1.18), noninvasive mechanical ventilation (NIMV) (p = 0.014, OR = 4.83, CI = 1.37-17.03), and bronchoscopy (p = 0.002, OR = 8.14, CI = 2.10-31.55). Pneumonia is a common complication in the CTICU, and the authors recommend the following: the removal of the endotracheal tube as soon as possible, the minimal use of a bronchoscope and only in cases of bronchial obstruction, and the use of NIMV.

Nicht-invasive Beatmung: was gibt es Neues?

Non-invasive mechanical ventilation (NIV) has become an essential therapeutic tool for the management of acute respiratory failure (ARF), but is still underrepresented in many intensive care units. In order to promote its more widespread use in the acute care setting, the German "Clinical Practice Guideline: Non-invasive Mechanical Ventilation as Treatment of Acute Respiratory Failure" has been recently published. NIV should be used selectively depending on the cause of respiratory failure and the clinical presentation. Strong evidence supports the use of NIV in hyper-capnic respiratory failure due to COPD exacerbation, with hyper-capnic coma no longer being a contraindication, as well as in the facilitation of weaning of COPD patients requiring intubation. Evidence for NIV as a first-line therapy is much lower in hypoxemic ARF without pre-existing pulmonary or cardiac insufficiency: only in highly selected patients with immunosuppression and after lung surgery could advantages be demonstrated. In hypoxemic ARF, failure of NIV not only occurs much more often compared to hypercapnic ARF, but NIV failure is also associated with increased mortality in these patients. Therefore, the indication for NIV must be checked more carefully and monitoring must be done more frequently than for hypercapnic ARF. With growing experience in the use of such non-invasive ventilation techniques, it will be increasingly used in the acute care setting. For example, in the prevention of extubation failure in patients at risk, endoscopic interventions in patients with ventilatory insufficiency, preoxygenation and bronchoscopy-guided intubation in severe hypoxemia and in palliative treatment.

Use of non-invasive mechanical ventilation in the Emergency Department, clinical outcomes and correlates of failure

Background: Despite several studies having been carried in this organizational context, there is an absence of information about the effectiveness of non-invasive mechanical ventilation (NIV) in Emergency Departments (ED), based on a number of suitable patients with acute respiratory failure (ARF) of different aetiology. In particular, it has not yet been defined as to whether the context of the ED suits the necessary requirement of quality for the correct application of the method and if the obtained results are different from those taken in other studies in general or respiratory intensive care unit. Finally there are few data related to the predictive factors to NIV failure (endotracheal intubation, in-hospital mortality) when applied in the emergency setting. Methods: To answer these questions we have retrospectively studied a population of 210 patients (95 with COPD exsacerbation ; 92 with acute cardiogenic pulmonary oedema; 23 with severe community acquired pneumonia) treated for ARF in the “critical area” of four Italian level II Emergency Departments. For all patients demographic data; some comorbidities (diabetes, dementia, sopraventricular arrhythmias, obesity); the physiological scores (Kelly, SAPS II, Apache II); the need for pharmacological sedation; vital and blood gas parameters (evaluated at entry, after one hour of treatment and before its suspension); the ventilatory modality applied (CPAP or PSV + PEEP) and some parameters of in-hospital stay (duration of the hospitalization in the critical area, duration of ventilation, compliance to the treatment, patient's refusal to continue it, development of skin necrosis, need for endotracheal intubation, in-hospital mortality) were considered. Finally demographic, event of death with Cox regression or to the need for ETI through linear regression analysis. Results: Globally, in-hospital mortality reached 13,3%, the percentage of failure with consequent endotracheal intubation amounted to 10,4% . Considering the single aetiologic groups in the patients with COPD, exsacerbation mortality and ETI percentage were 12,6% and 13,7% respectively; in ACPO patients these data respectively amounted to 3,3% and 4,3%; while for patients with severe CAP they respectively reached 34,7% and 21,7%. The following factors were independently correlated with in-hospital mortality: SAPS II > 35, presence of dementia for COPD patients; SAPS II > 35; presence of dementia, presence of sopraventricular arrhythmias for ACPO patients; SAPS II > 35, presence of sopraventricular arrhythmias, presence of dementia for CAP patients. Considering the whole population of 210 patients, the predictive factors of in-hospital mortality were the following: SAPS II > 35; presence of dementia; presence of sopraventricular arrhythmias; maintenance of a respiratory rate above 24 bpm during tratment. The following were factors independently correlated with the need for endotracheal intubation: male gender, pH < 7,32, respiratory rate > 24 bpm, mean arterial pressure > 96 mmHg, all measured at one hour of treatment, for COPD patients; male gender sex, pH < 7,32 , respiratory rate > 24 bpm, PaCO2> 54,5 mm Hg all measured after one hour treatment for ACPO patients. Given the low number of patients, it was not possible to perform the logistic regression and to calculate the matrix of covariance of the parameter for the CAP group. Considering the whole series of patients, the factors independently correlated to ETI resulting in the following: male gender; diagnosis of COPD; pH < 7,32, respiratory rate > 24 bpm, mean arterial pressure > 96 mm Hg, PaCO2 > 54,5 mm Hg, all measured after one hour treatment. Conclusions: In conclusion, our study shows that NIV is racticable in the ED with safety and clinical results I T A L I A N J O U R N A L O F P U B L I C H E A L T H JPH - Year 6, Volume 5, Number 3, 2008 T H E M E P A P E R S 1 9 9

Physiologic Effects of Noninvasive Ventilation in Patients With Chronic Obstructive Pulmonary Diseas

Noninvasive mechanical ventilation has been of use in the treatment of some forms of chronic and acute respiratory failure. However, the benefits of its use in patients in the stable phase of severe chronic obstructive pulmonary disease (COPD) remain unclear. A combination of continuous positive airway pressure (CPAP) and pressure support ventilation (PSV) may improve respiratory mechanics and alveolar ventilation, and reduce inspiratory muscle effort. In this study, we analyzed the physiologic effects of differing levels of CPAP and CPAP plus PSV in patients with stable severe COPD. Work of breathing, breathing pattern, oxygen saturation measured by pulse oximetry, PaO2, and PaCO2 were analyzed in a group of 18 patients under the following conditions: a) baseline; b) CPAP, 3 cm H20; c) CPAP, 6 cm H20; d) CPAP 3 cm H20 plus PSV 8 cm H20; and e) CPAP 3 cm H20 plus PSV 12 cm H20. CPAP at pressures of 3 and 6 cm H20 was associated with an increase in tidal volume (VT) from a mean (SD) baseline value of 0.52 (0.04) L to 0.62 (0.04) and 0.61 (0.03) L, respectively. Minute ventilation increased from 8.6 (0.5) L/min to 10.8 (0.6) and 10.9 (0.5) L/min, respectively. Mean inspiratory flow (VT/Ti) increased from 0.35 (0.02) L/s to 0.44 (0.02) and 0.41 (0.02) L/s, respectively, and dynamic intrinsic positive end-expiratory pressure (PEEPi,dyn) was reduced from 1.63 (0.7) cm H20 to 1.1 (0.06) and 0.37 (0.4) cm H20, respectively. CPAP did not reduce the work of breathing. Association of CPAP at 3 cm H20 with PSV of 8 or 12 cm H20 increased VT to 0.72 (0.07) and 0.87 (0.08) L, respectively, while minute ventilation increased to 12.9 (0.8) and 14.9 (1.1) L/s, respectively. Mean inspiratory flow also increased to 0.50 (0.03) and 0.57 (0.03) L/s, respectively. Work of breathing was reduced from 0.90 (0.01) J/L to 0.48 (0.06) and 0.30 (0.06) J/L, respectively, while PEEPi,dyn increased to 1.30 (0.02) and 2.42 (0.08) cm H20, respectively. With combined CPAP of 3 cm H20 and PSV of 12 cm H20, PaCO2 was reduced from a baseline value of 41.2 (1.5) mm Hg to 38.7 (1.9) mm Hg. All of the changes were statistically significant (P< .05). CPAP of 3 cm H20 in combination with PSV improved breathing pattern, increased alveolar ventilation, and reduced work of breathing. These results offer a rational basis for the use of noninvasive mechanical ventilation in the treatment of patients with stable severe COPD.

The use of noninvasive mechanical ventilation in COPD with severe hypercapnic acidosis

To compare the effect of noninvasive mechanical ventilation (NIV) in severely acidotic with mildly acidotic patients with acute hypercapnic chronic obstructive lung disease (COPD). Comparison of NIV in consecutively enrolled patients with acute hypercapnic COPD with mild (pH 7.25-7.35) or severe (pH<7.25) acidosis on time to normalise pH and improve PaCO(2), duration of NIV treatment, length of stay in hospital and survival. Results (meadian (IQR)): Twenty-nine patients had 36 episodes of acute hypercapnic respiratory failure: Seventeen with pH<7.25 and 19 with pH 7.25-7.34. Compared with the mildly acidotic group, the severely acidotic group took a similar length of time for pH to normalise and PaCO(2) improve (12 (6-34) vs 12 (4-28)h, respectively, P=0.42), with similar duration of NIV treatment (60 (35-96) vs 68 (36-48)h, respectively, P=0.25) and hospital length of stay (8 (7-18) vs 9 (5-17) days, respectively, P=0.61). Overall survival was 89%, with 95% in the mild and 82% in the severely acidotic groups. Noninvasive ventilation is effective in the treatment of patients with severe acidosis due to acute hypercapnic COPD.

Effect of non‐invasive ventilation on survival, quality of life, respiratory function and cognition: A review of the literature

Symptoms of nocturnal hypoventilation may negatively influence the quality of life (QoL) of ALS patients long before respiratory failure ensues. Non-invasive mechanical ventilation (NIV) is considered a treatment option for nocturnal hypoventilation. The primary objective of NIV is improving quality of life (QoL). It may also prolong life by several months. A systematic review of the literature was performed to analyse what is known of the effect of NIV on survival, QoL and other outcome measures. A computerized literature search was performed to identify controlled clinical trials and observational studies of treatment of ALS-associated nocturnal hypoventilation from 1985 until May 2005. Twelve studies fulfilled the inclusion criteria. Four studies were retrospective, seven prospective and in one study randomization was used. All studies reported beneficial effects of NIV on all outcome measures. In seven studies NIV was associated with prolonged survival in patients tolerant for NIV, and five studies reported an improved QoL. In conclusion, studies on the use of NIV in ALS differ in study design and endpoint definitions. All studies suggest a beneficial effect on QoL and other outcome measures (Evidence level Class II-III). Well-designed randomized controlled trials comparing the effect on QoL and survival have not been performed.

The Use of Noninvasive Mechanical Ventilation for the Treatment of Acute Exacerbations of Copd in Canada

Noninvasive mechanical ventilation (NIMV) is accepted as a life-saving treatment for patients presenting to the emergency department and other acute care settings with severe exacerbations of chronic obstructive pulmonary disease (COPD). It was hypothesized that there is marked national variability in the use of NIMV. Therefore, the use of NIMV for COPD exacerbations in urban centres across Canada was evaluated. All Canadian hospitals affiliated with a university training program were surveyed, and a request for involvement in this survey was posted on the Canadian Society of Respiratory Therapy professional practice listserv. Survey information was received from all 33 sites (100%) that were contacted. Marked differences in the application of NIMV were identified across all regions in Canada, ranging from requiring extensive monitoring in the intensive care unit to application on a general internal medical unit with intermittent noninvasive blood pressure monitoring. There were sites that rarely used NIMV for COPD exacerbations and others where it was routine practice. NIMV is a life-saving treatment for acute exacerbations of COPD. Despite clear clinical evidence, its use has not penetrated throughout all the larger urban hospitals in Canada. This may be more problematic in sites without 24 h respiratory therapy support. There are barriers to the routine application of NIMV that can be overcome using established guidelines and available evidence.

Treatment of Acute Exacerbations of Chronic Respiratory Failure: Integrated Use of Negative Pressure Ventilation and Noninvasive Positive Pressure Ventilation

Acute respiratory failure (ARF) can be treated with either invasive mechanical ventilation (IMV) or noninvasive mechanical ventilation (NIMV), which can spare the complications of artificial airways. To evaluate the efficacy of an integrated approach using negative pressure ventilation (NPV) with iron lung and noninvasive positive pressure ventilation (NPPV), we performed a prospective study in a group of patients admitted to our respiratory ICU (RICU) for ARF due to exacerbation of chronic respiratory failure (CRF). RICU at "R. Silvestrini" Hospital in Perugia, Italy. One hundred fifty-two consecutive patients were included in the study and treated with iron lung as first choice or, when contraindicated or not tolerated, with NPPV using a nasal or facial mask. After 2 h of noninvasive mechanical ventilation (NIMV), the patients were reevaluated; in case of clinical deterioration, patients receiving NPV were switched to NPPV. When NPPV as a first or second line of treatment failed the patients were intubated. One hundred fifty-two patients received NIMV, 97 with iron lung as the first choice of treatment, and 55 with NPPV. Six patients treated with NPV were switched to NPPV during the first 2 h of treatment. Twenty-five patients required IMV. The success rate of the integrated use of NIMV (NPV plus NPPV) was 81.6%, compared to that of NPV (83.5%) and NPPV (70.5%). Twenty-one patients (13.8%) required tracheostomy; the duration of hospital stay was significantly lower in patients treated with NIMV only. Thirty patients required mechanical ventilation at home. Few severe complications were observed in patients receiving IMV. The integrated use of two NIMV techniques is effective in patients with acute exacerbation of CRF. In most cases intubation and tracheostomy were avoided, thus reducing the complication rate of mechanical ventilation.

Noninvasive mechanical ventilation in clinical practice: a 2-year experience in a medical intensive care unit.

To evaluate the feasibility and outcome results of noninvasive mechanical ventilation (NIV) in daily clinical practice outside any prospective protocol-driven trial. An observational retrospective cohort study. A 22-bed medical intensive care unit in a university hospital. A consecutive cohort of 124 patients who underwent 143 NIV trials, regardless of the indication, over two consecutive years (1997-1998). None. A total of 604 acute respiratory failure patients underwent mechanical ventilation, and 143 NIVs were performed in 124 patients. The overall prevalence of NIV use was 143 of 604 patients (24%) in three groups: hypoxemic acute respiratory failure (29.5%), hypercapnic acute respiratory failure (41%), and weaning/postextubation (29.5%). Intubation was avoided in 92 of 143 of the NIVs performed (64%), 19 (13%) after changing the initial NIV mode (i.e., a success rate of 62%, 51%, and 86% in the three groups, respectively). A total of 35 of 51 intubated patients (69%) required intubation during the first 24 hrs of NIV. Intensive care unit stay was 12 +/- 10 days for the overall population, and mortality, when NIV failed, was 13 of 124 patients (10.5%). Arterial pH (p =.0527) and the Pao2/Fio2 ratio (p =.0482) after 1 hr were the only independent predictive factors for NIV failure by multivariate analysis. This study confirms the results of controlled trials and demonstrates the feasibility and efficacy of NIV applied in daily clinical practice. These results suggest that NIV should be considered as a first-line ventilatory treatment in various etiologies of acute respiratory failure and as a promising weaning technique and postextubation ventilatory support. However, NIV should certainly be performed by a motivated and sufficiently trained care team.

Respiratory support in spinal muscular atrophy type I: a survey of physician practices and attitudes.

To determine whether there is variability in the attitudes and practices of physicians regarding treatment of respiratory failure in children with spinal muscular atrophy type I (SMA type I) and, if so, whether this variation is associated with professional training. This was a descriptive, cross-sectional survey mailed to a randomly selected subset of the Child Neurology Society, pediatric members of the Society of Critical Care Medicine and to the membership of the Pediatric Interest Section of the American Academy of Physical Medicine and Rehabilitation. A scenario of a child with SMA type I in respiratory distress was followed by questions that explored practices and attitudes regarding mechanical ventilation. Fifty-seven percent of intensivists (75 of 132), 39% physiatrists (61 of 155), and 34% of neurologists (61 of 155) responded. Specialists differed as to whether they offered and/or recommended respiratory support to patients with SMA type I. Intensivists were less likely to offer and recommend tracheostomy than physiatrists. Intensivists were also significantly less likely than physiatrists to agree with statements supporting the ethical necessity of noninvasive mechanical ventilation (NIMV) and intubation in the setting of an acute respiratory illness, and NIMV and tracheostomy in the setting of chronic respiratory failure. Although parallel differences were found between physiatrists and neurologists regarding their attitudes toward mechanical ventilation, no significant differences were detected between intensivists and neurologists. Finally, physicians who reported that a high percentage of their patients with SMA type I received "comfort care only" also tended to view mechanical ventilation, ie, use of NIMV for chronic respiratory failure, use of intubation for an acute respiratory infection, and use of tracheostomy for chronic respiratory failure as an unreasonable intervention in most circumstances. We found a wide variation in physician practice regarding the mechanical ventilation of patients with SMA type I. This study suggests a wide variation not only in what is recommended but also in what is actually offered to families of these children. Furthermore, the study suggests that physician training and attitudes affect recommendations regarding mechanical ventilation and ultimately family decision making.

Very early extubation and non invasive ventilation after lung transplantation

In recent years non invasive mechanical ventilation (NIV), delivered through facial or nose mask, has been successfully used as an effective treatment for acute respiratory failure and as a technique for weaning [1,2,3]. The aim of this study was to evaluate the use of NIV after very early extubation in lung transplanted patients.

Physiologic Evaluation of 4 Weeks of Nocturnal Nasal Positive Pressure Ventilation in Stable Hypercapnic Patients with Chronic Obstructive Pulmonary Disease

Background: The long-term daily use of noninvasive mechanical ventilation (NIMV) to treat chronic respiratory failure in chronic obstructive pulmonary disease (COPD) patients is not widely recommended, partly because of a lack of clear clinical results and partly because the physiological mechanisms by which the daily application of NIMV would be helpful in these patients have not yet been clarified. Objectives: We designed a physiological study in order to assess the effects of supervised long-term NIMV on gas exchange, respiratory muscle function, pulmonary mechanics and to ascertain the possible effect of the treatment in responders and nonresponders. Methods: Fourteen consecutive inpatients with stable hypercapnic COPD (pH = 7.37 ± 0.01; PaCO₂ = 56.73 ± 6.48 mm Hg) underwent 4 weeks of nocturnal NIMV delivered with a bilevel ventilator ‘physiologically’ set to reduce tidal transdiaphragmatic pressure (Pdi) by at least 50% and the amount of dynamic intrinsic positive end-expiratory pressure by 70%. Various measurements were compared with those obtained in a control group of consecutive patients with comparable baseline characteristics who refused NIMV and underwent breathing exercises for the same period of time. Results: By the end of the 4 weeks NIMV had induced a slight but significant (p < 0.01) reduction in resting PaCO₂ (53.78 ± 5.64 mm Hg) associated with a decrease in the pressure time product of the diaphragm per minute (from 172 ± 60 to 136 ± 61 cm H₂O/l/s; p < 0.05). This latter value was primarily due to a significant shortening of the inspiratory duty cycle, while Pdi and lung mechanics were not modified. Eight of the 13 NIMV-treated patients (1 dropped out for nonmedical reasons) had a clear reduction in PaCO₂ (>3 mm Hg or >5% from enrollment) and were classified as responders. The acute reduction in PaCO₂ during the first trial with NIMV resulted to be a strong index of the final response. The subgroup of responders had a significantly increased maximal Pdi (from 41 ± 19 to 49 ± 23 cm H₂O, p < 0.05) and an enhanced ability of the ventilatory pump to clear CO₂ (9.7 ± 3.4 vs. 7.2 ± 2.9 cm H₂O × s/min; p < 0.01). No significant changes were observed in the control group. Conclusions: These results suggest that in a remarkable and identifyable proportion of patients with stable hypercapnic COPD, nocturnal NIMV may decrease resting PaCO₂, reraising the role of chronically supporting the respiratory pump.

Non-invasive mechanical ventilation in status asthmaticus.

To evaluate our clinical experience with the use of non-invasive mechanical ventilation (NIMV) in patients with an acute asthmatic attack. Seven-year period retrospective observational study. General intensive care department (ICU) of a county hospital. From 1992 to 1998, we documented clinical data, gas exchange and outcome of every asthmatic patient admitted to our ICU because of status asthmaticus (SA) refractory to initial medical therapy. Clinical charts were reviewed and patients were allocated to two groups according to their suitability as participants in an NIMV trial. Patients who arrived in respiratory arrest and those who ultimately improved with medical management alone were not considered candidates for NIMV. For the present analysis, the rest of the patients were considered candidates for NIMV, while the decision to start a NIMV trial or to perform endotracheal intubation (ETI) remained at the discretion of the attending physician. When patients failed to improve with NIMV, standard mechanical ventilation (MV) with ETI was initiated. Fifty-eight patients were included in the study. Twenty-five patients (43%) were not eligible for NIMV: 11 patients (19%) because of respiratory arrest on their arrival at the Emergency Room and 14 patients (24%) because of improvement with medical management (bronchodilators, corticoids and oxygen). The remaining 33 patients were eligible for NIMV (57%): 11 patients (33%) received invasive MV and 22 patients (67%) were treated with NIMV. Three NIMV patients (14%) needed ETI. We compared data at baseline, 30 min, 2-6 h and 6-12 h after the onset of ventilatory support. Significant differences were observed in arterial blood gases on admission to the Emergency Room between MV and NIMV: PaCO2 (89 +/- 29 mmHg vs 53 +/- 13 mmHg, p < 0.05), pH (7.05 +/- 0.21 vs 7.28 +/- 0.008, p < 0.05) and HCO3- level (22 +/- 5 mmol/l vs 26 +/- 6 mmol/l, p < 0.05). No differences were found in the median length of ICU stay (4.5 vs 3 days), median hospital stay (15 vs 12 days) and mortality (0 vs 4%). Face mask NIMV appears to be a suitable method for improving alveolar ventilation and can reduce the need for intubation in a selected group of patients with SA.

Noninvasive Mechanical Ventilation for Children and Adolescents with Spinal Cord Injuries

Many children and adolescents with SCI have impairment of respiratory function because of decreased innervation to muscles of respiration. This article discusses the anatomy and physiology of respiration, evaluation following SCI, indications for use of noninvasive mechanical ventilation (NMV) following SCI, types of NMV, and the use of assisted cough and the exsufflator.

Bilateral Diaphragm Paralysis Secondary to Central von Recklinghausen's Disease

Bilateral paralysis of the diaphragm is either idiopathic or associated with several medical conditions, including trauma or thoracic surgery, viral infections, and neurologic congenital or degenerative disorders. We describe the case of a 36-year-old man with a history of neurofibromatosis who developed severe bilateral diaphragmatic paralysis from involvement of the phrenic nerve roots with neurofibromas. The patient manifested progressive exertional dyspnea and debilitating orthopnea requiring the use of noninvasive mechanical ventilation at night. A review of the literature reveals that neurofibromatosis is an unrecognized cause of diaphragmatic paralysis.

Use of Noninvasive Mechanical Ventilation in AcuteHypercapnic versus Hypoxic Respiratory Failure

연구배경: 기존의 양압환기법은 기관내관이나 기관절개술을 통해서만 시행되어 왔으나 최근 이러한 인공기도에 의한 기도합병증을 피하기 위한 방법으로 안연 또는 코마스크를 환자~인공환기기 사이의 매체로 이용하는 비침습적 환기법 (noninvasive positive pressure ventilation, 이하 NIV라 함)이 시도되고 있다. 이에 저자 등응 급성호흡부전 환자들에서 NIV의 적용 가능성, 치료성공율 및 치료성공과 연관된 지표를 알아보고자 본 연구를 시행하였다. 방법: 대상응 급성 환기부전 (acute vemilarory failure, 이하 VF : $PaCO_2$ > 43 mrn Hg & pH $PaO_2/FIO_2$ $pH{\geq}7.35$ )으로 기계호흡이 필요했던 환자 106 예 중 NIV 시도가 가능한 환자 26명이었으며, 총 VF 19예 중 11 예 (57.9%) (남 : 여 =7 : 4, $55.4{\pm}14.6$ 세), 총 OF 87예 중 15 예 (17.2%) (남 : 여 =12 : 3, $50.6{\pm}15.6$ 세)에서 NIV 시도가 가능하였다. 결과: 1. 기관내삽관 없이 NIV로 기계호흡 이탈까지 성공한 환자는 VF에서 81.8% (9/11), OF에서 40%(6/15)였다. NIV 의 합병증은 코부위 피부괴사와 가스성 위장 팽대 각 1예씩 이었다. 2. 환기부전 환자의 NIV 성공 예 에서 분당호흡 수는 기저치에 비해 NIV 시작 12시간 후(각각 $34{\pm}9$ 회, $26{\pm}6$ 회, p=0.045)에 유의한 감소를 보였다. $PaCO_2$ 와 pH는 모두 기저치에 비해 NIV 시작 24시간 후( $PaCO_2$ 각각 $87.3{\pm}20.6$ , $81.2{\pm}9.1$ mm Hg, p $7.26{\pm}0.04$ , $7.32{\pm}0.02$ , p $PaCO_2$ 는 NIV 시작전 (각각 $59.8{\pm}9.2$ , $76.0{\pm}22.8$ mm Hg), NIV 시작 후 30분 (각각 $121.5{\pm}20.2$ , $99.6{\pm}35.8$ mm Hg,), 6시간 (각각 $100.0{\pm}26.4$ , $76.2{\pm}22.3$ mm Hg) 및 12시간 ( $88.7{\pm}28.7$ , $74.3{\pm}16.7$ mm Hg)에 서로 유의한 차이가 없었으나 (모두 p > 0.05), $PaO_2/FIO_2$ 비는 NIV 성공 예에서는 각각 $120.0{\pm}19.6$ , $218.9{\pm}98.3$ , $191.3{\pm}55.2$ 및 $232.8{\pm}17.6$ mm Hg (p=0.0211)로 상승한 반면, 실패 예에서는 $127.9{\pm}63.0$ , $116.8{\pm}24.4$ , $100.6{\pm}34.6$ 및 $129.8{\pm}50.3$ mm Hg (p=0.5319)로 유의한 상승이 관찰되지 않았다. 결론: 비침습적 환기법은 급성 환기부전군에서 급성 산소화부전에 비해 적용성과 성공율이 높으며, 환기부전의 NIV 성공 예에서는 분당호흡수의 감소가 선행하고 $PaO_2$ 와 pH의 호전이 뒤따랐고 산소화부전에서는 NIV 시작 30분 후의 $PaO_2/FIO_2$ 비가 성공적 NIV 적용 여부의 한 예측 지표가 될 수 있을 것으로 사료되었다. 【Background : We prospectively evaluated the applicability and effect of noninvasive ventilation (NIV) in acute respiratory failure and tried to find out the parameters that could predict successful application of NIV. Methods : Twenty-six out of 106 patients with either acute ventilatory failure (VF: $PaCO_2$ > 43 mm Hg with pH $PaO_2/AO_2$ $pH{\geq}7.35$ ) requiring mechanical ventilation were managed by NIV (CPAP + pressure suppon, or BiPAP) with face mask. Eleven out of 19 cases with VF (57.9%) (M : F=7 : $55.4{\pm}14.6$ yrs) and 15 out of 87 cases with OF (17.2%) (M : F=12 : 3, $50.6{\pm}15.6$ yrs) were s uilable for NIY. Respiratory rates, arterial blood gases and success rate of NIV were analyzed in each group. Results: 81.8% (9/11) of YF and 40% (6/15) of OF were successfully managed on NIV and were weruled from mechanical ventilator without resorting to endotracheal intubation. Complications were noted in 2 cases (nasal skin necrosis 1, gaseous gastric distension 1). In NIV for ventilatory failure, the respiration rate was significantly decreased at 12 hour of NIV ( $34{\pm}9$ /min pre-NIV, $26{\pm}6$ /min at 12 hour of NIV, p=0.045), while $PaCO_2$ ( $87.3{\pm}20.6$ mm Hg pre-NIV, $81.2{\pm}9.1$ mm Hg at 24 hour of NIV) and pH ( $7.26{\pm}0.04$ , $7.32{\pm}0.02$ , respectively, p $PaCO_2$ were not different between the successful and the failed cases at pre-NIV and till 12 hours after NIV. The $PaO_2/FIO_2$ ratio, however, significantly improved at 0.5 hour of NIV in successful cases and were maintained at around 200 mm Hg (n=6 : at baseline, 0.5h, 6h, 12h : $120.0{\pm}19.6$ , $218.9{\pm}98.3$ , $191.3{\pm}55.2$ , $232.8{\pm}17.6$ mm Hg, respectively, p=0.0211), but it did not rise in the failed cases (n=9 : $127.9{\pm}63.0$ , $116.8{\pm}24.4$ , $100.6{\pm}34.6$ , $129.8{\pm}50.3$ mm Hg, respectively, p=0.5319). Conclusion : From the above results we conclude that NIV is effective for hypercapnic respiratory failure and its success was heralded by reduction of respiration rale before the reduction in $PaCO_2$ level. In hypoxic respiratory failure, NIV is much less effective, and the immediate improvement of $PaO_2/FIO_2$ ratio at 0.5h after application is thought to be a predictor of successful NIV.】