Noninvasive positive pressure ventilation as treatment for acute respiratory failure in critically ill patients

Our current state of knowledge on noninvasive positive pressure ventilation (NPPV) and technical aspects are discussed in the present review. In patients with chronic obstructive pulmonary disease, NPPV can be considered a valid therapeutic option to prevent endotracheal intubation. Evidence suggests that, before eventual endotracheal intubation, NPPV should be considered as first-line intervention in the early phases of acute exacerbation of chronic obstructive pulmonary disease. Small randomized and non-randomized studies on the application of NPPV in patients with acute hypoxaemic respiratory failure showed promising results, with reduction in complications such as sinusitis and ventilator-associated pneumonia, and in the duration of intensive care unit stay. The conventional use of NPPV in hypoxaemic acute respiratory failure still remains controversial, however. Large randomized studies are still needed before extensive clinical application in this condition.     

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.     

无创呼吸机治疗急性左心功能衰竭的临床疗效

目的研究无创呼吸机治疗急性左心功能衰竭的临床价值。方法对22例经药物治疗后30 min仍无效的急性左心功能衰竭患者采用无创呼吸机通气治疗,观察患者治疗前后临床症状、体征及呼吸频率、心率、脉搏血氧饱和度(SpO2)、动脉血氧分压(PaO2)等的变化。结果经无创呼吸机治疗后有18例症状缓解,有效率达81.8%,呼吸频率(RR)、心率(HR)较治疗前明显下降(P0.01),SpO2、PaO2较治疗前明显上升(P0.01),差异均有统计学意义。结论无创呼吸机通气可作为药物治疗效果不佳的重症急性左心功能衰竭的较好治疗方法。     

Noninvasive ventilation for acute respiratory failure

Noninvasive ventilation refers to any form of ventilatory support applied without the use of an endotracheal tube. It offers the potential to provide primary treatment for acute respiratory failure while avoiding complications associated with mechanical ventilation with endotracheal intubation. Noninvasive ventilation has been most commonly studied in hypercapnic respiratory failure. A review of randomized, controlled studies shows mixed results and methodologic limitations affect the interpretation of current evidence. Patient selection is clearly the most important issue in considering noninvasive ventilation for acute respiratory failure. Unfortunately, patients who benefit from noninvasive ventilation represent only a minority of the total group with any one disease, and thus it is difficult to make broad conclusions concerning applicability of this treatment modality. Future studies are needed to focus on determining the specific patient populations who will benefit the most, evaluating the optimal ventilatory mode and mask for providing noninvasive ventilation, and clarifying its impact on clinical outcomes. This revised version was published online in July 2006 with corrections to the Cover Date.     

Noninvasive ventilation for acute respiratory failure

PURPOSE OF REVIEW: This review critically examines recent literature related to applications of noninvasive ventilation in the acute setting. RECENT FINDINGS: Recent articles have strengthened the evidence supporting the use of noninvasive ventilation for patients with cardiogenic pulmonary edema and exacerbation of severe chronic pulmonary obstructive disease. In the former, however, it remains unclear whether noninvasive ventilation offers any significant advantages over continuous positive airway pressure. The rate of myocardial infarction seems to be no higher when patients with cardiogenic pulmonary edema are treated with noninvasive ventilation rather than continuous positive airway pressure, although caution is still advised in patients with acute coronary syndromes. Noninvasive ventilation also does not seem to increase the risk of dissemination of severe acute respiratory syndrome to health care workers as long as strict isolation procedures are used. Noninvasive ventilation facilitates weaning in patients with chronic obstructive pulmonary disease but should not be used routinely to treat extubation failure, and necessary intubation should not be delayed. Guidelines for the use of noninvasive ventilation can alter caregivers' behavior but have not been clearly shown to improve outcomes. Outcomes do seem to improve, however, as caregivers acquire experience with the technique. SUMMARY: The recent literature has refined some of the current indications for noninvasive ventilation in the acute-care setting, including chronic pulmonary obstructive disease and cardiogenic pulmonary edema. Guidelines for use are now being developed, and outcomes seem to be improving, partly as a consequence of greater caregiver experience and possibly related to technologic advances.     

无创双水平正压通气对不同病因急性呼吸衰竭的治疗评价

目的：研究无创双水平正压通气(BiPAP)对心源性肺水肿和重症社区获得性肺炎所致呼吸衰竭的治疗效果。方法：49例急性呼吸衰竭患者分为心源性肺水肿组(25例)和重症肺炎组(24例)，均应用BiPAP进行治疗，观察两组的治疗效果。结果：两组患者应用BiPAP治疗后早期氧合均得到明显改善；心源性肺水肿组在BiPAP治疗时间、气管插管率、死亡率方面均明显低于重症肺炎组。结论：无创正压通气在早期可以纠正心源性肺水肿和重症肺炎合并呼吸衰竭患者的氧合，但最终的预后因呼吸衰竭的病理类型不同而有很大区别。     

Noninvasive ventilation in acute respiratory failure

BACKGROUND: Noninvasive ventilation has assumed an important role in the management of respiratory failure in critical care units, but it must be used selectively depending on the patient's diagnosis and clinical characteristics. DATA: We review the strong evidence supporting the use of noninvasive ventilation for acute respiratory failure to prevent intubation in patients with chronic obstructive pulmonary disease exacerbations or acute cardiogenic pulmonary edema, and in immunocompromised patients, as well as to facilitate extubation in patients with chronic obstructive pulmonary disease who require initial intubation. Weaker evidence supports consideration of noninvasive ventilation for chronic obstructive pulmonary disease patients with postoperative or postextubation respiratory failure; patients with acute respiratory failure due to asthma exacerbations, pneumonia, acute lung injury, or acute respiratory distress syndrome; during bronchoscopy; or as a means of preoxygenation before intubation in critically ill patients with severe hypoxemia. CONCLUSION: Noninvasive ventilation has assumed an important role in managing patients with acute respiratory failure. Patients should be monitored closely for signs of noninvasive ventilation failure and promptly intubated before a crisis develops. The application of noninvasive ventilation by a trained and experienced intensive care unit team, with careful patient selection, should optimize patient outcomes.     

早期无创正压通气纠正急性左心衰竭所致严重低氧血症效果观察

目的观察早期无创正压通气（noninavasive positive pressure ventilation，NPPV）对急性左心衰竭所致严重低氧血症的治疗效果。方法40例急性左心衰（心功能Ⅳ）患者随机分为NPPV组和常规治疗组，两组均常规给予强心、利尿、镇静、扩血管等对症支持治疗，NPPV组在常规治疗的基础上采用双向气道正压呼吸机（BiPAP）经面罩双向正压通气治疗，常规治疗组则给予普通高浓度吸氧。观察治疗2小时后两组患者心率、呼吸、血压、脉搏、血氧饱和度（SaO2）、血气分析和临床症状体征的变化。结果NPPV组所有患者HR下降，呼吸困难症状缓解，生命体征平稳，PaO2、SaO2明显增高，缺氧程度得到有效改善，治疗总有效率100％（20／20）；常规治疗组总有效率70％（14／20）。结论重度左心衰患者在抗心衰药物治疗的同时使用BiPAP面罩双相气道正压无创通气可以较快纠正机体缺氧状况，改善心功能，缩短病程。     

Noninvasive ventilation in patients with hypoxemic acute respiratory failure

PURPOSE OF REVIEW: To discuss the recent literature concerning the use of noninvasive ventilation for hypoxemic acute respiratory failure. RECENT FINDINGS: The benefits of noninvasive ventilation for patients with hypoxemic acute respiratory failure are unclear. In immunocompromised patients and following thoracic surgery, there is a strong rationale for using noninvasive ventilation to treat acute respiratory failure. Prophylactic continuous positive airway pressure after abdominal or thoracic surgery and prophylactic noninvasive ventilation in patients at risk of extubation failure have proved beneficial. Recent studies show that noninvasive ventilation has a favourable impact in immunocompetent patients with acute lung injury/acute respiratory distress syndrome, but caution is required. In hypoxemic acute respiratory failure after extubation, one study reported excess mortality in patients treated with noninvasive ventilation, possibly related to the delay for intubation. A major issue is avoiding undue noninvasive ventilation prolongation and staying alert for predictors of early noninvasive ventilation failure. Caution, close monitoring, and broad experience are required. SUMMARY: Hypoxemic acute respiratory failure may benefit from noninvasive ventilation or continuous positive airway pressure, but undue prolongation should be avoided. In postextubation respiratory failure there is no evidence for routine use of noninvasive ventilation.     

Noninvasive pressure support versus proportional assist ventilation in acute respiratory failure

Background Although conventional pressure ventilation (PSV) decreases the rate of intubation in acute respiratory failure, patient-ventilator dyssynchrony is a frequent cause of failure. In proportional assist ventilation (PAV), pressure is applied by the ventilator in proportion to the patient-generated volume and flow; therefore, there is automatic synchrony between the patient's effort and the ventilatory cycle.Objective The aim of this study was to compare the effects of PSV and PAV during noninvasive ventilation in the treatment of acute respiratory failure.Design Prospective randomised study.Setting A multidisciplinary 24-bed intensive care unit of an acute-care teaching hospital in Alicante, Spain.Patients This study included 117 consecutive adult patients with acute respiratory failure randomised to noninvasive ventilation delivered by PSV (n = 59) or PAV (n = 58).Measurements and results There were no statistically significant differences between patients assigned to each mode of ventilation with regard to baseline parameters and aetiological diagnoses of acute respiratory failure. With regard to outcome data, no significant differences were observed between PSV and PAV in the frequency of intubation (37% vs 34%), mortality rate (29% vs 28%), and mean length of stay. Subjective comfort (0–10 visual analogue scale) was rated higher and intolerance occurred less frequently (3.4% vs 15%, P = 0.03) in the PAV than in the PSV mode.Conclusions Although PAV seems more comfortable and intolerance occurred less frequently, no major differences exist in terms of physiological improvement or in terms of outcomes when comparing PSV and PAV.An editorial regarding this article can be found in the same issue ()     

无创正压通气治疗急性肺损伤/急性呼吸窘迫综合征的观察

目的 评价无创正压通气(NPPV)治疗急性肺损伤(ALI)／急性呼吸窘迫综合征(ARDS)患者的临床效果。方法 对18例ALI/ARDS患者实施NPPV治疗结果进行回顾性总结，分析NPPV治疗前后动脉血氧分压／吸氧浓度(PaO2／FiO2)、呼吸频率(RR)和心率(HR)的变化。结果 NPPV治疗成功率为55.6％(10／18)，8例NPPV治疗失败患者中7例改用气管插管有创通气。总死亡率为33．3％(6／18)。NPPV成功组50％(5／10)为ALI患者，治疗后1～2h PaO2／FiO2、RR和HR较治疗前有显著改善。NPPV失败组均为ARDS患者，治疗后1-2h PaO2／FiO2、RR和HR无明显变化。结论 NPPV对部分ALI／ARDS患者是有效的支持治疗手段，尤其是ARDS早期的ALI阶段可考虑选用NPPV。如NPPV治疗失败，应及时转换为气管插管有创通气。     

Non‐invasive positive pressure ventilation in patients with acute respiratory failure

Non‐invasive positive pressure ventilation is an emerging modality in contemporary critical care practice. Perhaps the most widely utilized and familiar form of non‐invasive positive pressure ventilation is mask continuous positive airway pressure. Other common modes include mask Bi‐level positive airway pressure and mask pressure support ventilation. All feature the delivery of positive airway pressure via a mask (full‐face, naso‐oral or nasal), and a patient‐controlled respiratory cycle. The physiological benefits of non‐invasive positive pressure ventilation suggested by a number of studies include improved oxygenation, decreased work of breathing, improved ventilation and perfusion matching, decreased fatigue, and increased minute ventilation. The utilization of non‐invasive positive pressure ventilation has now been reported for a variety of clinical indications. In most, randomized trials are lacking, and the benefits and preferred mode of non‐invasive positive pressure ventilation are still to be elucidated. In general, in patients that are candidates for endotracheal intubation, non‐invasive positive pressure ventilation should be used as a way to possibly avoid endotracheal intubation rather than as an alternative to endotracheal intubation. Whilst the benefit of non‐invasive positive pressure ventilation appears to be established in patients with chronic obstructive airways disease with hypercapnic acute respiratory failure, one of the major unresolved issues is whether one modality is significantly better than the others. Unfortunately, the question of whether Bi‐level positive airway pressure is better than continuous positive airway pressure in this clinical scenario has not been satisfactorily addressed in any large randomized and controlled clinical trial. Further, there is no ‘gold standard’ for predicting success with non‐invasive positive pressure ventilation, although several studies have looked at this aspect.     

无创正压通气与有创正压通气治疗急性呼吸衰竭的比较研究

目的　比较无创正压通气 (NPPV)和有创正压通气 (IPPV)救治急性呼吸衰竭 (ARF)的临床效果 ,评估NPPV在ARF治疗中的作用。方法　将各种原因所致ARF 5 2例患者随机分为NPPV组 (2 6例 )和IPPV组 (2 6例 ) ,在给予病因治疗同时分别实施NPPV和IPPV。观察分析两组患者在治疗过程中动脉血气变化、并发症的发生率及治疗结果。结果　NPPV组有 7例 (2 6 .9% )治疗失败转为气管插管IPPV ,其中 4例 (15 .4 % )死亡。IPPV组死亡 5例 (19.2 % ) ,两组死亡率无显著差异 (P >0 0 5 )。两组治疗有效患者在分别接受NPPV和IPPV治疗后 6h动脉血气有相似的显著改善。NPPV组患者机械通气时间和住院时间短于IPPV组 (P <0 .0 5 )。NPPV组的并发症发生率低于IPPV组 (P <0 .0 5 )。结论　在经过选择的ARF患者中 ,应用NPPV治疗的临床效果与IPPV相似。实施NPPV可缩短机械通气和住院时间 ,减少并发症。且因为无创伤性 ,NPPV可作为经过选择的ARF患者首选的通气支持治疗手段。     

Noninvasive ventilation for acute hypoxemic respiratory failure in patients with COVID-19

AimNoninvasive ventilation (NIV) is known to reduce intubation in patients with acute hypoxemic respiratory failure (AHRF). We aimed to assess the outcomes of NIV application in COVID-19 patients with AHRF.Materials & methodsIn this retrospective cohort study, patients with confirmed diagnosis of COVID-19 and AHRF receiving NIV in general wards were recruited from two university-affiliated hospitals. Demographic, clinical, and laboratory data were recorded at admission. The failure of NIV was defined as intubation or death during the hospital stay.ResultsBetween April 8 and June 10, 2020, 61 patients were enrolled into the final cohort. NIV was successful in 44 out of 61 patients (72.1%), 17 patients who failed NIV therapy were intubated, and among them 15 died. Overall mortality rate was 24.6%. Patients who failed NIV were older, and had higher respiratory rate, PaCO₂, D-dimer levels before NIV and higher minute ventilation and ventilatory ratio on the 1-st day of NIV. No healthcare workers were infected with SARS-CoV-2 during the study period.ConclusionsNIV is feasible in patients with COVID-19 and AHRF outside the intensive care unit, and it can be considered as a valuable option for the management of AHRF in these patients.     

Noninvasive mechanical ventilation as a palliative treatment of acute respiratory failure in patients with end-stage solid cancer

Noninvasive ventilation (NIV) is widely used in the treatment of acute respiratory failure (ARF), but not in patients with end-stage solid cancer in whom any form of mechanical ventilation tends to be avoided. In a prospective study, we investigated the use of NIV in 23 patients with solid malignancies receiving palliative care and who were affected by severe hypoxic or hypercapnic ARF. The most frequent causes of ARF were exacerbations of pre-existing pulmonary diseases and pneumonia. After one hour, NIV significantly improved PaO2/FiO2 (from 154+/-48 to 187+/-55) and the Borg dyspnoea score (from 5.5+/-1.2 to 2.3+/-0.3). NIV also improved pH, but only in the subset of hypercapnic patients. Thirteen of 23 (57%) patients were successfully ventilated and discharged alive, while 10/23 patients (43%) met the criteria for intubation or died after an initial trial of NIV. Only two of these patients accepted invasive ventilation. The mortality rate in this subgroup was 9/10 (90%). A higher Simplified Acute Physiology Score (SAPS II) and a lower PaO2/FiO2 on admission were associated with a lower probability of survival. Patients with ARF and end-stage solid malignancies have an overall ICU and 1-year mortality rate of 39% and 87%, respectively, but despite this, a consistent subset of patients may still be successfully treated with NIV, if the cause of ARF is reversible.     

Noninvasive proportional assist ventilation compared with noninvasive pressure support ventilation in hypercapnic acute respiratory failure

OBJECTIVES: To compare short-term administration of noninvasive proportional assist ventilation (NIV-PAV) and pressure support ventilation (NIV-PSV). DESIGN: Prospective, crossover, randomized study. SETTING: Medicosurgical intensive care unit in a nonteaching hospital. PATIENTS: Twelve chronic obstructive pulmonary disease patients admitted for hypercapnic acute respiratory failure. INTERVENTION: NIV-PSV and NIV-PAV given in a randomized order after baseline evaluation in continuous positive airway pressure. Using a flow-triggering ventilator, NIV-PAV was adjusted using the runaway method and compared with NIV-PSV at similar peak inspiratory airway pressure. MEASUREMENTS AND MAIN RESULTS: Flow, airway pressure, and changes in esophageal pressure were measured and the tidal volume, the patient's inspiratory work of breathing, and the esophageal pressure--time product were calculated. Arterial pH and PaCO(2) were measured and breathing comfort was assessed using a visual analogic scale. Peak inspiratory airway pressure (17 +/- 3 cm H(2)O) and tidal volume were similarly increased with the two modalities with no change in respiratory rate. The change in esophageal pressure was similarly decreased (from 20 +/- 8 cm H(2)O in continuous positive airway pressure to 12 +/- 7 in NIV-PSV and 10 +/- 5 cm H(2)O in NIV-PAV) as well as inspiratory muscle effort indexes. Arterial pH and PaCO(2) were similarly improved. Breathing comfort was significantly improved in NIV-PAV (+38 +/- 38%) but not in NIV-PSV (+11 +/- 23%). The tidal volume was more variable in NIV-PAV (89 +/- 18%) than in NIV-PSV (15 +/- 8%) and changes in tidal volume variability were significantly correlated (p =.02) with changes in breathing comfort. CONCLUSIONS: In chronic obstructive pulmonary disease patients with hypercapnic acute respiratory failure, NIV-PAV was able to unload inspiratory muscles similarly to NIV-PSV but may be more comfortable than NIV-PSV.