Noninvasive ventilation in acute respiratory failure

Noninvasive PPV has been employed for decades in patients with chronic respiratory failure. Increasing use in patients with acute respiratory failure is a more recent phenomenon, mainly because of advances in noninvasive interfaces and ventilator modes. Noninvasive PPV delivered by nasal or oronasal mask has been demonstrated to reduce the need for endotracheal intubation, decrease lengths of stay in the ICU and hospital, and possibly reduce mortality. In the acute care setting, evidence now demonstrates the efficacy of noninvasive PPV for acute exacerbations of COPD, pulmonary edema, pulmonary contusions, and acute respiratory failure in patients who decline or who are not believed to be candidates for intubation. No firm conclusions can yet be made regarding patients with respiratory failure due to other causes, but studies suggest that noninvasive PPV may also be of benefit in patients with postoperative respiratory insufficiency, chest wall disease, and cystic fibrosis. Several factors are vital to the success of this therapy, including careful patient selection, properly timed intervention, a comfortable, well-fitting interface, patient coaching and encouragement, and careful monitoring. Noninvasive ventilation should be used as a way to avoid endotracheal intubation rather than as an alternative. Accordingly, a trial of noninvasive ventilation should be instituted in the course of acute respiratory failure before respiratory arrest is imminent, to provide ventilatory assistance while the factors responsible for the respiratory failure are aggressively treated. Moreover, the authors favor conservative management with expeditious intubation in patients who have other conditions that place them at risk during use of noninvasive ventilation or in patients failing to respond to noninvasive PPV. Noninvasive PPV clearly represents an important addition to the techniques available to manage patients with acute respiratory failure; however, because most studies have been retrospective and uncontrolled, many issues remain unresolved. Further controlled studies are needed to confirm the safety and efficacy of noninvasive PPV, evaluate the most appropriate selection of patients and timing of intervention, define the best type of interface, and assess the costs of noninvasive PPV in comparison with conventional therapy.     

Noninvasive positive-pressure ventilation for acute respiratory failure in a medical intensive care unit in Singapore

The main advantage of noninvasive ventilation over conventional mechanical ventilation is in the avoidance of endotracheal intubation and its related complications. Currently, the role of noninvasive ventilation in the management of patients with acute respiratory failure is still not firmly established. We conducted a prospective study to evaluate the efficacy of nasal positive pressure ventilation in patients with acute respiratory failure. Thirty-three consecutive patients with acute failure in whom intubation and mechanical ventilation were strongly considered were included in the study. They received ventilatory support by means of BiPAP ventilatory support system and nasal mask. Physical findings and laboratory measurements were documented before and at specific intervals after initiation of support. Eighty per cent (24/30) of patients were successfully supported. Successfully supported patients tolerated the device with improved gas exchange, hence avoiding endotracheal intubation. The mean duration of support was 19.2 hours. There were major associated complications, e.g. gastric distention or aspiration.     

Noninvasive ventilation for postoperative support and facilitation of weaning

Noninvasive ventilation includes continuous positive airway pressure with mask, positive pressure ventilation with mask, and negative pressure body ventilation. Noninvasive ventilation is a ventilatory support mode intermediate in both effectiveness and potential complications between oxygen administration and intubation with mechanical ventilation. The advantages, disadvantages, and experimental results of the use of noninvasive ventilation in patients who have been extubated following recovery from surgery and subsequently experience respiratory difficulties are discussed. In general, noninvasive ventilation seems to provide useful ventilatory support in about three of four patients in whom it is tried. In addition, the use of noninvasive ventilation as an aid to weaning of patients from mechanical ventilation is discussed. This use of noninvasive ventilation has not yet been extensively reported, although it appears to be potentially useful.     

Noninvasive management of pediatric neuromuscular ventilatory failure

OBJECTIVE: To evaluate the use of mouth piece/nasal intermittent positive-pressure ventilation (IPPV) as an alternative to intubation or to permit extubation for patients with primarily neuromuscular ventilatory impairment and no ventilator-free breathing ability. DESIGN: A case control study. INTERVENTIONS: Using a protocol in which oxyhemoglobin desaturation was prevented or reversed by the continuous use of noninvasive IPPV and manually and mechanically assisted coughing as needed, patients with neuromuscular ventilatory failure and no ventilator-free breathing ability were managed noninvasively or extubated to continuous use of noninvasive IPPV for ventilatory support on room air. MEASUREMENTS AND MAIN RESULTS: Four of ten patients who presented in acute ventilatory failure were managed without intubation, despite becoming dependent on continuous ventilator use. The six intubated patients were extubated successfully to continuous noninvasive IPPV once normal arterial oxygen saturation levels could be maintained on room air, despite their having no ventilator-free breathing ability. CONCLUSIONS: The use of inspiratory and expiratory aids can decrease the need for intubation for patients with neuromuscular ventilatory failure in the absence of significant lung disease. It can also permit extubation, despite the need for continuous ventilatory support and, thereby, decrease the need to resort to tracheostomy.     

Central alveolar hypoventilation in neurosarcoidosis

Although the lung is almost always involved in sarcoidosis and respiratory failure is not uncommonly caused by intrinsic lung disease, chronic alveolar hypoventilation on the basis of neurosarcoidosis has not been previously described. This report describes the case of a 42-year-old woman with sarcoidosis and documented involvement of the lungs, muscle, peripheral nerves, and skin. She presented with ventilatory failure and a vital capacity of 700mL and required hospitalization for intubation and mechanical ventilation. After failing ventilator weaning attempts and requiring continuous ventilatory assistance, she was extubated to continuous use of noninvasive intermittent positive pressure ventilation (IPPV). She eventually weaned to nocturnal-only use of noninvasive IPPV. However, her PaCO2 remained elevated during daytime hours despite the fact that her vital capacity had returned to 3,600mL. She was not obese, and her oxyhemoglobin saturation (SaO2) was normal on room air. Subsequent attempts to discontinue nocturnal nasal IPPV resulted in marked nocturnal decreases in SaO2 and return of symptoms. This case illustrates successful noninvasive management of an apparently unique occurrence of central alveolar hypoventilation caused by neurosarcoidosis.     

Noninvasive ventilation in neuromuscular disease

The treatment of respiratory failure in patients who have NMD continues to be an evolving process. Negative-pressure ventilation, once prominent in the 1940s and 1950s, gave way to intermittent positive-pressure ventilation with tracheostomy or endotracheal tubes in the 1960s. Now there is a resurgence of noninvasive ventilation, brought about by innovative modes of positive pressure delivered through nasal and facial masks. Although frequently relegated to second-line choices, negative-pressure devices still offer a practical treatment alternative as patient preference still plays a role in selecting a proper mode of ventilation. Studies have shown that noninvasive ventilation can prevent or reverse respiratory failure and improve quality of life and longevity. Despite the seemingly widespread acceptance of noninvasive ventilation in the treatment of respiratory failure, physicians still appear reluctant to use ventilatory assistance in the neuromuscular arena. In 1985, a survey found that respiratory support systems were utilized routinely in only 33% of the 132 responding Muscular Dystrophy Association (MDA) clinics. Bach recently surveyed 273 MDA clinic directors and co-directors from 167 clinics, to evaluate their current use of mechanical ventilation. Ventilatory assistance was recommended and used electively in only 43 (26%) of the 167 clinics. Furthermore, it was the policy in 68 of the clinics to discourage the use of mechanical ventilation. Even more importantly, only 2 physicians who discouraged the use of mechanical ventilation were familiar with the newest noninvasive methods of ventilatory support. Sadly, although our methodologies in the treatment of respiratory failure continue to improve, physician practice has lagged behind. Physicians who treat patients who have NMD need to become cognizant of these new techniques and incorporate them into their present therapeutic armamentarium.     

Noninvasive pressure support ventilation in COPD patients with postextubation hypercapnic respiratory insufficiency

Patients with chronic obstructive pulmonary disease (COPD) who have been intubated and mechanically ventilated may prove difficult to wean. Noninvasive ventilation may be used in an attempt to avoid new endotracheal intubation. The efficacy of administration of noninvasive pressure support ventilation was evaluated in 30 COPD patients with postextubation hypercapnic respiratory insufficiency, compared with 30 historically matched control patients who were treated conventionally. Patients were included in the study if, within 72 h postextubation, they presented with respiratory distress, defined as the combination of a respiratory frequency >25 breaths x min(-1), an increase in the arterial carbon dioxide tension (Pa,CO2) of at least 20% compared with the value measured after extubation, and a pH <7.35. Noninvasive pressure support ventilation was effective in correcting gas exchange abnormalities. The use of noninvasive ventilation significantly reduced the need for endotracheal intubation: 20 of the 30 patients (67%) in the control group required endotracheal intubation, compared with only six of the 30 patients (20%) in the noninvasive-ventilation group (p<0.001). In-hospital mortality was not significantly different between the two groups, but the mean duration of ventilatory assistance for the treatment of the postextubation distress, and the length of intensive care unit stay related to this event, were both significantly shortened by noninvasive ventilation (p<0.01). In conclusion, noninvasive ventilation may be used in the management of patients with chronic obstructive pulmonary disease and postextubation hypercapnic respiratory insufficiency.     

Respiratory insufficiency in neuronopathic and neuropathic disorders

Twenty-nine patients with a neuronopathic or neuropathic disorder were referred for assessment of respiratory insufficiency between 1978 and 1994. Diagnoses included spinal muscular atrophy (6), chronic idiopathic demyelinating neuropathy (4), Vialetto-van Laere syndrome (3), hereditary motor and sensory neuropathy (3) and a miscellaneous group (5). We also describe seven patients with Guillain-Barré syndrome (GBS) who required long-term ventilatory support for over 6 months to 7 years after the initial illness. Respiratory insufficiency occurred as a consequence of respiratory muscle weakness, impaired bulbar function and restrictive lung defects. In some groups presentation was with progressive nocturnal hypoventilation culminating in acute respiratory failure. Five patients with GBS or chronic idiopathic demyelinating neuropathy were weaned from ventilatory support up to 18 months after the initial illness. The remaining 24 patients required continuous or nocturnal ventilatory support using intermittent positive-pressure ventilation (13), negative pressure ventilation (4), nasal-mask-delivered intermittent positive-pressure ventilation (4), nasal-mask-delivered continuous positive-pressure ventilation (3), mouthpiece-assisted ventilation by day (2) and rocking bed (1). None have been weaned from support after a period of ventilation ranging from one month to 10 years. Eight patients have subsequently died.     

Correction of deficiencies in flexible fiberoptic sigmoidoscope cleaning and disinfection technique in family practice and internal medicine offices

We describe a 27-year-old primigravida suffering from cystic fibrosis. Her chest was colonised with Burkholderia cepacia and she was in respiratory failure for which she required constant nasal intermittent positive pressure ventilation. In view of her rapid deterioration, Caesarean section was performed under epidural anaesthesia at 25 weeks gestation. A live 790-g boy was delivered. Post-operatively she made steady progress for 5 days although still requiring nasal ventilatory support. Thereafter she developed pneumonia and required tracheal intubation and ventilation on the eighth day. Her increasing hypoxaemia and pulmonary hypertension failed to respond to any therapy including inhaled nitric oxide and she died on the tenth postoperative day.     

A miniature mechanical ventilator for newborn mice

Transgenic/knockout mice with pre-defined mutations have become increasingly popular in biomedical research as models of human diseases. In some instances, the resulting mutation may cause cardiorespiratory distress in the neonatal or adult animals and may necessitate resuscitation. Here we describe the design and testing of a miniature and versatile ventilator that can deliver varying ventilatory support modes, including conventional mechanical ventilation and high-frequency ventilation, to animals as small as the newborn mouse. With a double-piston body chamber design, the device circumvents the problem of air leakage and obviates the need for invasive procedures such as endotracheal intubation, which are particularly important in ventilating small animals. Preliminary tests on newborn mice as early as postnatal day O demonstrated satisfactory restoration of pulmonary ventilation and the prevention of respiratory failure in mutant mice that are prone to respiratory depression. This device may prove useful in the postnatal management of transgenic/knockout mice with genetically inflicted respiratory disorders.     

Neuromuscular ventilatory insufficiency: effect of home mechanical ventilator use v oxygen therapy on pneumonia and hospitalization rates

The purpose of this study was to determine rates of pneumonia and hospitalization for patients receiving oxygen therapy, patients having indwelling tracheostomy tubes, and those using tracheostomy or noninvasive methods of home mechanical ventilation. Six hundred eighty-four users of assisted ventilation for 13,751 patient-years or 19.8 years per patient were surveyed by mail and twice by telephone over a span of four years. Pneumonia and hospitalization rates were significantly higher for ventilator users with chronic obstructive pulmonary disease or with neuromuscular ventilatory insufficiency and gastrostomy tubes than for ventilator users with neuromuscular ventilatory insufficiency without gastrostomy tubes. Of the latter group, more than 90% of the pneumonias and hospitalizations were triggered by otherwise benign intercurrent upper respiratory tract infections. Oxygen therapy was associated with a significantly (P < 0.001) higher rate of pneumonias and hospitalizations than that seen for untreated patients after initial episodes of respiratory distress or during the use of either tracheostomy intermittent positive pressure ventilation or noninvasive ventilatory assistance methods. The lowest pneumonia and hospitalization rates (P < 0.001) were by full-time, noninvasive intermittent positive pressure ventilation users. We conclude that oxygen therapy is not an effective substitute for assisted ventilation for patients with primarily ventilatory insufficiency. Noninvasive ventilatory aids can be used effectively for up to full-time ventilatory support for patients with neuromuscular conditions whose bulbar muscle function is adequate to avert the need for gastrostomy tube placement.     

Emergency intubation with the Combitube in a patient with persistent vomiting

Prompt establishment of a patient airway and effective ventilation are the major goals during initiation of cardiopulmonary resuscitation in patients with cardiac arrest. Endotracheal intubation is the definitive method to maintain an optimal airway. However, endotracheal intubation is not always possible, even for the skilled physician. The Combitube has been developed to overcome this disadvantage. Studies have proved the effectivity of ventilation with this device. A case is reported where a patient suffered from acute respiratory failure and attempts at endotracheal intubation failed due to continued vomiting rendering fibre-optical visualisation of the vocal cords impossible. Blind insertion of the Combitube led to successful ventilation, and hence replacement by an endotracheal airway could be performed without danger of aspiration.     

Noninvasive positive pressure ventilation: what is its role in treating acute respiratory failure?

Noninvasive positive pressure ventilation (NIPPV) is a viable option in treating appropriately selected patients with acute respiratory failure. It is often well tolerated, and it avoids endotracheal intubation with its potential complications. Moreover, gas exchange is reportedly improved. Several issues relating to the use of NIPPV are unresolved, however. The optimal interface, best ventilator mode, and patient selection criteria have not been firmly established. Also, studies are needed to compare the efficacy, safety, and cost-effectiveness of NIPPV and standard endotracheal ventilation. Despite these unresolved issues, NIPPV clearly represents an important addition to the techniques available in managing acute respiratory failure. Except in situations in which immediate endotracheal intubation is required, it may become first-line therapy in elderly patients in whom resuscitation status is unsettled.     

Kyphosis secondary to tuberculosis osteomyelitis as a cause of ventilatory failure. Clinical features, mechanisms, and management

STUDY OBJECTIVES: To investigate the relationship of thoracic kyphosis following tuberculosis to the development of ventilatory failure and to assess the efficacy on nocturnal noninvasive ventilatory support. DESIGN: Retrospective consecutive case series with crossover from a phase without noninvasive ventilatory support to a phase with this treatment. SETTING: The Respiratory Support and Sleep Centre, Papworth, Hospital, Cambridge, England. PATIENTS: Seven patients with thoracic kyphosis following tuberculous osteomyelitis which had been contracted by the age of 4 years were studied. Their mean age was 53 (SD 7.1) years and the mean angle of kyphosis was 113.60. All patients were in ventilatory failure. INTERVENTIONS: The patients were treated with nocturnal noninvasive ventilation with either an individually constructed cuirass shell and a negative pressure pump or nasal intermittent positive pressure ventilation using a volume preset ventilator. MEASUREMENT AND RESULTS: Each patient underwent an initial clinical assessment along with radiologic studies of the spine, pulmonary function tests, daytime arterial blood gas tensions, and overnight recordings of arterial saturation, and transcutaneous carbon dioxide tension. They were reassessed in detail at a mean of 5 years after starting ventilatory support. Symptoms, vital capacity, daytime carbon dioxide tension, and overnight oximetry had all improved following treatment. Temporary withdrawal of ventilatory support led to severe sleep fragmentation in four patients and the appearance of central apneas and hypopneas in the other three. Six of the 7 patients were alive at a mean of 5.7 years after starting nocturnal ventilation. CONCLUSION: These results show that ventilatory failure may develop, after an interval of many years, in patients with a severe thoracic kyphosis due to tuberculosis in childhood. Noninvasive nocturnal ventilatory support can control the symptoms of ventilatory failure, improve the physiologic abnormalities, and is associated with prolonged survival.     

Apoptosis of undifferentiated progenitors and granule cell precursors in the postnatal human cerebellar cortex correlates with expression of BCL-2, ICE, and CPP32 proteins

This article reviews the literature of noninvasive positive pressure ventilation (NPPV) in patients with acute respiratory failure. The article divides acute respiratory failure into the categories of primary ventilation failure and oxygenation failure, and examines various diagnostic groups within these categories. Although the use of NPPV for patients with acute respiratory failure of other etiologies requires further study, the authors conclude that there is sufficient evidence to support the use of NPPV in acute, severe exacerbations of chronic obstructive pulmonary disease.     

Respiratory failure based on pulmonary tuberculosis sequelae and its management

According to the complexity of pathological change of pulmonary tuberculosis sequelae (TB seq), on which respiratory failure based shows the higher incidence of marked degree of hypoxemia and hypercapnia than that based on chronic pulmonary emphysema (CPE). In TB seq, pulmonary artery mean pressure is higher, nocturnal oxyhemoglobin desaturation is much lower than in CPE. Also hypoxemia on exercise is lower, and oxygen inhalation for this hypoxemia is more effective than in CPE. The most effective therapy is continuous oxygen therapy. Home oxygen therapy has improved the prognosis and quality of life (QOL) of patients with respiratory failure based on TB seq. Artificial positive pressure ventilation (TIPPV) with intubation or tracheotomy is carried out for patients with severe hypercapnia and respiratory acidosis. Recently, early application of nasal mask ventilation (NPPV) on patients with TB seq has prohibited acute exacerbation of chronic respiratory failure. And also for patients with severe hypercapnia, NPPV with BIPAP method is effective for their QOL. Comprehensive respiratory rehabilitation is also successfully applied for their management.     

Study of the use of noninvasive ventilation of the lungs in acute respiratory insufficiency due exacerbation of chronic obstructive pulmonary disease

Noninvasive positive pressure ventilation (NPPV) is a life-saving procedure in acute respiratory failure (ARF), but its technique is not yet in routine use in many respiratory centers. We carried out a prospective randomized study comparing the combination of NPPV with conventional therapy (oxygen, bronchodilators, steroids, and theophylline) with conventional therapy alone in patients with acute respiratory failure caused by exacerbation of chronic obstructive pulmonary disease (COPD). A total of 58 patients were recruited from a large group of patients admitted to our hospital between September 1995 and March 1997. Twenty-nine patients were randomly assigned to the NPPV group and 29 to the conventional (non-NPPV) group. The patients were matched for demographic and physiological norm values (mean age 63.4 +/- 5.5 vs. 66.2 +/- 7.1 years, mean FEV1 0.68 +/- 0.15 vs. 0.74 +/- 0.16 L, PaO2 51.4 +/- 6.8 vs. 52.3 +/- 6.5 mm Hg, PaCO2 63.4 +/- 10.9 vs. 64.9 +/- 9.7 mm Hg, and pH 7.28 +/- 0.07 vs. 7.26 +/- 0.06). The outcome end points were needed for endotracheal intubation, length of hospital stay, and incidence of complications. NPPV was administered using BiPAP ventilatory device (Respironics, Inc.) by spontaneous and spontaneous/timed modes via nasal and facial masks. The mean time of NPPV was 29 +/- 25 h. Three patients refused from NPPV because of intolerance of mask or ventilation procedure. Two of them were eventually intubated and one of them died. In patients administered NPPV, we observed a significant rise of pH and fall of PaCO2 after 1 h of ventilation, in contrast to the non-NPPV group (7.34 +/ 0.09 vs. 7.21 +/- 0.08, p < 0.05; 53.2 +/- 10.7 vs. 71.4 +/- 10.2 mm Hg, p < 0.01, respectively). The need in intubation was lower in the NPPV group as compared to the reference group (12 vs. 28%, p = 0.18), mortality rate was higher in the non-NPPV group (31 vs. 8%, p = 0.03), and hospital stay was shorter in NPPV patients (26 +/- 7 vs. 34 +/- 10 days). The incidence of complications was lower in the NPPV group, they were less significant, and did not involve discontinuation of ventilation. Hence, NPPV is a first-line therapy in patients with ARF caused by COPD exacerbation, due to obvious advantages over conventional methods of treatment.     

Respiratory muscles and ventilatory failure: 1993 perspective

Some conditions that predispose to ventilatory failure increase the work of breathing (chronic obstructive pulmonary disease [COPD], obesity, kyphoscoliosis), whereas others cause severe respiratory muscle weakness. Specific reasons for muscle weakness include critical illness (electrolyte imbalance, acidemia, shock, sepsis), chronic illness (poor nutrition, cachexia), and neuromuscular diseases. Inspiratory muscle weakness from mechanical disadvantage to the diaphragm is characteristic of asthma and COPD. The increased work of breathing combined with muscle weakness increases the pressure needed to inspire a breath and decreases maximal inspiratory pressure. When this pressure exceeds 0.4, dyspnea and inspiratory muscle fatigue ensue. One way to lower this pressure and avert fatigue is to lower the tidal volume. Ventilatory drive is high, not low, in ventilatory failure. Concomitant shortening of inspiration and breath duration cause the small tidal volume and increased respiratory rate. Gas exchange is compromised by ventilation/perfusion imbalance, and the ratio of dead space to tidal volume is also increased by rapid, shallow breathing. Reduction in tidal volume minimizes dyspnea, but the small tidal volume is inadequate for gas exchange. Acute treatment of respiratory muscle failure involves respiratory muscle rest through mechanical ventilation and removal of noxious influences (infection, metabolic disarray), whereas chronic treatment involves rebuilding the contractile apparatus by nutritional repletion and training.     

Intracerebral bispecific ligand-antibody conjugate increases survival of animals bearing endogenously arising brain tumors

Noninvasive ventilation (NIV) is the provision of ventilatory support to a spontaneously breathing patient without endotracheal intubation. In this review, we detail concerns related to endotracheal intubation and summarize the physiologic effects and clinical application of NIV. We then address the use of NIV in 5 conditions of particular interest to the practitioner of emergency medicine: exacerbated chronic obstructive lung disease, severe asthma, patients who are not candidates for endotracheal intubation, pneumonia, and pulmonary edema.     

Involvement of a 70-kb plasmid of the epidemic Shigella dysenteriae type 1 (Dt66) strain in drug-resistance, lipopolysaccharide synthesis, and virulence

During recent years home ventilation has been shown to be useful for a growing number of patients with neuromuscular diseases and respiratory insufficiency caused by weakness of the respiratory muscles. Despite its technical simplicity, home ventilation leads to a number of social, ethical, medical and infrastructural problems. This consensus paper discusses the special situation of patients with neuromuscular diseases in home ventilation and describes the current thinking in the following topics: (1) definition of home ventilation; (2) aims of home ventilation; (3) indications and preconditions of home ventilation; (4) techniques and forms of home ventilatory support; (5) preparation for and practical questions of home ventilation; (6) stopping home ventilation.