Traumatic tetraplegia: noninvasive respiratory management in the acute setting

A 15-yr-old patient with high-level spinal cord injury developed ventilatory failure 24 hr after hospital admission and required continuous ventilatory support. Although he lost all ventilator-free breathing tolerance, he was managed by receiving noninvasive intermittent positive-pressure ventilation rather than intermittent positive-pressure ventilation via an endotracheal intubation. Cooperative, uncomplicated, acutely injured patients with spinal cord injury who develop ventilatory failure are candidates to use noninvasive intermittent positive-pressure ventilation to avoid intubation.     

Noninvasive ventilation in chronic obstructive lung disease

Noninvasive mechanical ventilation is provided without establishing an endotracheal airway. In acute respiratory failure due to chronic obstructive lung disease, noninvasive positive-pressure ventilation delivered through a nasal or face mask may eliminate the need for intubation and related complications, reduce the duration of hospitalisation and improve survival compared to assisted ventilation through an endotracheal tube. In chronic respiratory failure related to neuromuscular diseases and thoracic deformities, the advent of noninvasive intermittent longterm ventilation is well established. However, it is not clear, whether addition of noninvasive ventilation to standard treatment with medication and longterm oxygen improves symptoms and survival in chronic respiratory failure due to chronic obstructive lung disease. During introduction of noninvasive ventilation, patients must be monitored closely. Patient selection and information, meticulous optimization of the ventilator settings and delivery system, education and experience of the personnel have an important impact on the success of this novel way of providing mechanical ventilatory support.     

Respiratory involvement in primary muscle disorders: assessment and management

Eighty-four patients with primary disorders of muscle were referredfor assessment of respiratory insufficiency between 1978 and1991. The eventual diagnoses were: 'limb girdle syndromes' (18patients), adult onset acid maltase deficiency (14), dystrophiamyotonica (13), inflammatory disorders (10), congenital myopathies(nine), rigid spine syndromes (five), dystrophies (Duchenne(six), facioscapulohumeral (four), Becker (one)) and miscellaneous(four). Presentations were often insidious, with progressivenocturnal hypoventilation culminating in respiratory failureor arrest, recurrent respiratory tract infections, or obstructivesleep apnoea. Respiratory symptoms developed relatively earlyin patients with acid maltase deficiency and inflammatory disordersbut parallelled the development of limb weakness in limb girdle,myotonic and congenital syndromes. Sixty-six patients receivedrespiratory support for a median of 5 years (1-34 years) usingvarious techniques of negative and positive pressure ventilation.Fourteen patients received short-term support for an episodeof respiratory failure before being weaned, 51 required nocturnaldomiciliary ventilation and one was dependent on continuousdomiciliary support. Tracheostomy was performed in 32 patientsand used for domiciliary nocturnal ventilation in 25. Twenty-eightpatients have subsequently died.     

Chronic obstructive pulmonary disease and sleep

The control of breathing in patients with chronic obstructive pulmonary disease (COPD) follows the same basic principles as in normal subjects, both awake and asleep, with an expected lower feedback response during sleep. This impacts nocturnal gas exchange and sleep quality most profoundly in patients with more severe COPD, as multiple factors come into play. Hypoventilation causes the most important gas-exchange alteration in COPD patients, leading to hypercapnia and hypoxemia, especially during rapid-eye-movement sleep, when marked respiratory muscle atonia occurs. The hypoxia leads to increased arousals, sleep disruption, pulmonary hypertension, and higher mortality. The primary mechanisms for this include decreased ventilatory responsiveness to hypercapnia, reduced respiratory muscle output, and marked increases in upper airway resistance. In the presence of more profound daytime hypercapnia, polysomnography should be considered (over nocturnal pulse oximetry) to rule out other co-existing sleep-related breathing disorders such as obstructive sleep apnea (overlap syndrome) and obesity hypoventilation syndrome. Present consensus guidelines provide insight into the proper use of oxygen, continuous positive airway pressure, and nocturnal noninvasive positive-pressure ventilation for those conditions, but several issues remain contentious. In order to provide optimal therapy to patients, the clinician must take into account certain reimbursement and implementation-process obstacles and the guidelines for treatment and coverage criteria.     

High-frequency jet ventilation in weaning the ventilator-dependent patient

Nine ventilator-dependent patients were successfully weaned from mechanical ventilatory support by high-frequency jet ventilation. All patients had been on ventilatory support for at least 2 wk, and had not responded to attempts at weaning by intermittent mandatory ventilation.     

High-frequency pulsation (HFP) in a patient with Guillain-Barré syndrome

A patient with Guillain-Barré syndrome (GBS) developed a respiratory crisis despite recurrent treatment with plasma exchange. Thus mechanical ventilatory support became necessary. As an alternative to conventional ventilatory techniques high-frequency pulsation (HFP), a modified high-frequency jet-ventilation technique was used. According to the observations HFP may be a valuable technique for the continuous adaptation to the patient's individual respiratory demands in GBS.     

Strapless oral-nasal interface for positive-pressure ventilation

A custom-fabricated strapless oral-nasal interface (SONI) is described. It was used in the long-term administration of intermittent positive-pressure ventilation (IPPV) by 18 patients with paralytic or restrictive pulmonary insufficiency. This interface is an acrylic shell which is firmly fixed to an orthodontic bite plate; it is designed to form a seal over the nose and mouth for the entry of IPPV. Eight patients were ventilator dependent 24 hours a day. The ten patients who required only nocturnal aid had improvement in daytime arterial blood gases. Although nine of these patients could manage less than 15 minutes of unassisted breathing (free time) supine, all slept supine on SONI IPPV. The 13 patients who underwent sleep monitoring maintained a mean oxygen saturation of 95.3% +/- 1.7% and acceptable end-tidal pCO2 (30 to 45 mmHg). These 13 patients have used SONI IPPV for an average of 22 months (range = 3 to 63 months). Impediments to successful long-term use of a SONI include the presence of a hyperactive gag reflex or stimulation of excessive oral secretions. When combined with mouth IPPV, glossopharyngeal breathing, the intermittent abdominal pressure ventilator, or the cuirass ventilator for daytime use, SONI IPPV is an option for the patient who prefers total ventilatory support by noninvasive means.     

Use of the rocking bed in the treatment of neurogenic respiratory insufficiency

We describe 53 patients who received ventilatory support witha rocking bed. Diagnoses included previous poliomyelitis (30),muscular dystrophy (12), motor neurone disease (4), adult-onsetacid maltose deficiency (4) and a miscellaneous group (3). Patientspresented with respiratory insufficiency characterized by diaphragmweakness, progressive nocturnal hypoventilation and/or acuteor chronic respiratory failure. Domiciliary rocking beds wereused by 43 patients for a mean of 16.0 years (range 1 monthto 35 years). Most patients were able to breathe adequatelyby day when sitting or standing, but needed assistance by rockingbed for 6–11 h when lying down for sleep. The rockingbed was well-tolerated, and associated with both symptomaticrelief and amelioration of arterial blood gas abnormalities.Seventeen of these 43 patients discontinued its use, eitherbecause of discomfort (9) or increasing respiratory insufficiency(8). The rocking bed is a valuable adjunct in the managementof the respiratory insufficiency associated with neuro-musculardisease.     

Weaning from mechanical ventilation: successful use of modified inspiratory resistive training in muscular dystrophy

An 18-yr-old man with Duchenne muscular dystrophy and ventilatory failure could not be weaned from mechanical ventilation using a T-piece method, despite repeated attempts over 3 months. Subsequently, we weaned the patient using inspiratory muscle resistive training (IRT), modified by the concurrent delivery of intermittent mandatory ventilation (IMV). During the training program, the sessions were gradually prolonged from 5 min to a maximum of 30 min, the IMV rate was gradually decreased, and the magnitude of the resistive load was gradually increased. After 45 days of training, his vital capacity had increased from 380 to 850 ml, his maximal inspiratory airway pressure from -28 to -50 cm H2O, and his tolerance of T-piece breathing, from less than 10 min to over 16 h. After an additional 2 wk of nocturnal mechanical ventilation, he was successfully weaned. We conclude that IRT with IMV can be an effective method of weaning patients who have severe ventilatory failure.     

Extubation criteria after weaning from intermittent mandatory ventilation and continuous positive airway pressure

The "traditional" weaning criteria, arterial blood gases, and a number of other physiologic variables were measured in 47 patients to evaluate to what extent reduced ventilatory reserves or extrapulmonary organ dysfunction affect successful extubation. All patients had been weaned from continuous positive airway pressure (CPAP) and from mechanical ventilation according to the intermittent mandatory ventilation (IMV) method; at the time of study, all patients had compromised arterial oxygenation relieved by supplemental inspired oxygen. No significant difference between patients successfully extubated and those who required reintubation was found using the traditional weaning criteria or blood gases. On the other hand, patients who required reintubation had significantly lower urine volume (p less than 0.01), lower respiratory quotient values (p less than 0.05), and a higher incidence of positive blood culture (p less than 0.05). These 3 variables also correlated best to the patients' outcome after extubation.     

An experimental study of different ventilatory modes in piglets in severe respiratory distress induced by surfactant depletion

In 19 anesthetized piglets 3 ventilatory modes were studied after inducing pulmonary insufficiency by bronchoalveolar lavage by the method of Lachmann. The lavage model was considered suitable for reproduction of severe respiratory distress. This model was reproducible and stable with respect to alveolar collapse, decrease in static chest-lung compliance and increase in extravascular lung water. The ventilatory modes studied were volume-controlled intermittent positive-pressure ventilation (IPPV), pressure-controlled inverse ratio ventilation (IRV), and pressure-controlled high-frequency positive-pressure ventilation (HFPPV). The 3 ventilatory modes were used in random sequence for at least 30 min to produce a ventilatory steady state. Ventilation with no PEEP, permitting alveolar collapse, was interposed between each experimental mode. The ability to open collapsed alveoli, i.e. alveolar recruitment, was different. The recruitment rate for IPPV was 74%, but for IRV and HFPPV it was 95%, respectively. Although IRV provided the best PaO₂, this was at the expense of high airway pressures with circulatory interference and reduced oxygen transport. In contrast to this, HFPPV provided lower airway pressures, less circulatory interference and improved oxygen transport. In the clinical setting there might be negative effects on vital organs and functions unless the ventilatory modes are continuously and cautiously adapted to the individual requirements in different phases of severe respiratory distress. Therefore, one ventilatory strategy could be to open the airways with IRV, but then switch to HFPPV in an attempt to maintain the airways open with lesser risk of barotrauma and with improved oxygen transport.This study was supported by the Swedish Medical Research Council (projects 4252 and 2710), Sweden     

Kyphoscoliosis ventilatory insufficiency: noninvasive management outcomes

OBJECTIVE: To determine the effects on symptoms, pulmonary function, sleep, and other clinical variables of treating kyphoscoliosis-associated chronic alveolar hypoventilation with nocturnal nasal ventilation. DESIGN: Sixteen patients with kyphoscoliosis were treated with nocturnal nasal ventilation delivered by volume-cycled (seven patients) and pressure-cycled (nine patients) ventilators. Dyspnea, morning headaches, fatigue, hypersomnolence, and perceived sleep quality were assessed. RESULTS: All pretreatment symptoms improved significantly with nasal ventilation. Likewise, PaO2 (mm Hg), PaO2/FlO2, PaCO2 (mm Hg), pH, and forced vital capacity (in milliliters and as a percentage of predicted normal) significantly improved with treatment. Maximum inspiratory pressures and maximum expiratory pressures also significantly increased. Tidal volumes increased significantly and breathing frequency decreased (not significant). Although perceived sleep quality improved, as well as sleep oxyhemoglobin saturation, there was no significant change in sleep architecture. Hospitalization days for respiratory difficulties also decreased from 10.9 +/- 13.3 days in the 6 mo before intermittent positive-pressure ventilation to 0 days during the first 6 mo of treatment. CONCLUSIONS: Although not apparently affecting sleep architecture, nocturnal nasal ventilation can significantly improve nocturnal and daytime blood gases, pulmonary function, and symptoms of hypoventilation for patients with severe kyphoscoliosis.     

Guillain-Barré syndrome

Guillain-Barré syndrome (GBS) is a group of autoimmune syndromes consisting of demyelinating and acute axonal degenerating forms of the disease. Nerve conduction study helps differentiate the heterogeneous subtypes of GBS. Patients exhibit a progressive paralysis that reaches a plateau phase. In most patients, resolution is complete or near complete. Mortality from GBS most often is associated with dysautonomia and mechanical ventilation. GBS usually is associated with an antecedent infection by one of several known pathogens. Cross-reactivity between the pathogen and the nerve tissue sets up the autoimmune response. Treatment consists of supportive care, ventilatory management (in about one third of patients), and specific therapy with intravenous immunoglobulin or plasmapheresis. Consultation with a neurologist is suggested.     

机械通气治疗连枷胸合并呼吸衰竭16例

目的探讨连枷胸致呼吸衰竭的病理生理、机械通气治疗的指征、模式参数调节及撤离.方法总结16例采用机械通气治疗的连枷胸合并呼吸衰竭病例的临床治疗过程及转归.结果其中13例经机械通气4～14d后一次性成功脱机,转普通病房继续治疗5～1 3d后出院;3例死亡病例分别死于重度颅脑损伤及失血性休克.结论连枷胸如有机械通气指征,应尽早使用.机械通气模式可选用SIMV(同步间歇指令通气)+PSV(压力支持),宜选择偏高潮气量(10～12ml/kg),PEEP(呼气末正压)有利于病情恢复.浅快呼吸指数(f/VT)是目前撤机最有预测价值的指标.     

Management of mitochondrial disease on an intensive care unit

Patients with mitochondrial disease may present to the IntensiveCare Unit (ICU) with a variety of neurological and general medicaldisorders. Eleven patients were admitted to a neurological ICUbetween 1970 and 1992 because of respiratory insufficiency,status epilepticus and/or metabolic encephalopathy associatedwith mitochondrial disease. Respiratory impairment occurredin eight patients and was associated with nocturnal hypoventilationdue to respiratory muscle weakness, aspiration due to bulbarweakness and abnormalities of central control leading to a reducedCO₂ drive, irregular respiratory patterns and sleep apnoea.Seven patients received continuous respiratory support duringthe acute illness; three were subsequently weaned to domiciliaryventilation, and four died. Five patients had stroke-like episodes,which in two were recurrent. Four patients developed tonic-clonicgrand mal epilepsy associated with myoclonic fits (2 patients),absences (2), focal fits (1) and status epilepticus (2). Encephalopathywas associated with recurrent lactic acidosis (2 patients),cardiac failure (2), hyponatraemia (2), renal abnormalities(3) and complete heart block (1). Although rare, mitochondrialdisease should be considered in any patient with unexplainedrespiratory failure, intractable epilepsy, lactic acidosis orrecurrent stroke.     

Noninvasive ventilation in acute exacerbations of chronic obstructive pulmonary disease in patients with and without home noninvasive ventilation

OBJECTIVE: The frequency of home ventilation has increased greatly. The objective of the study was, first, to compare the outcome of episodes of acute exacerbation of chronic obstructive pulmonary disease treated with mask intermittent positive-pressure ventilation (MIPPV) in patients with home MIPPV and in patients without home ventilatory support and, second, for each category of patients, to compare patients successfully ventilated with MIPPV with those who failed with MIPPV. DESIGN: Prospective, controlled, nonrandomized clinical study. SETTING: Medical intensive care unit of a university hospital. PATIENTS: In the groups with and without home MIPPV, respectively, 31 and 78 episodes of acute exacerbations of chronic obstructive pulmonary disease were studied. INTERVENTIONS: MIPPV was performed in a sequential mode and delivered through a full-face mask with a bilevel positive airway pressure system. MEASUREMENTS AND MAIN RESULTS: The clinical and functional characteristics of the two groups, at admission, were similar. In groups with and without home ventilation, respectively, success rates were 68% and 72% (p =.68), length of intensive care unit stay was 8 +/- 6 and 10 +/- 4 days (p =.02), and intensive care unit deaths were 13% and 8% (p =.30). In survivors and in groups with and without home ventilation, respectively, the total time of ventilatory assistance in intensive care unit was 5 +/- 4 and 8 +/- 4 days (p =.004), and the length of intensive care unit stay was 7 +/- 5 and 10 +/- 4 days (p =.003). A greater correction of pH, after 45 mins of MIPPV with optimal settings, was recorded in the success patients than in the failure patients, respectively; in the group with home MIPPV, the pH after 45 mins was 7.34 +/- 0.04 vs. 7.31 +/- 0.04 (p =.06), and in the group without home MIPPV, pH was 7.34 +/- 0.04 vs. 7.30 +/- 0.04 (p =.001). CONCLUSION: MIPPV may also be favorable during episodes of acute exacerbations in patients with chronic obstructive pulmonary disease. Experience with MIPPV could benefit selected patients in the management of acute respiratory failure.     

无创正压通气治疗SARS的临床评价

目的 :分析无创正压通气 (NIPPV)对严重急性呼吸综合征 (SARS)患者的氧合作用 ,并初步探讨机械通气时机把握问题。方法 :对 2 5例 SARS合并呼吸功能不全而使用 NIPPV治疗 2 4 h后患者的生理指标和氧合功能进行分析 ,然后再将他们分为生存组与死亡组 ,比较两组患者 NIPPV前后急性生理学与慢性健康状况 (APACHE )评分、改良呼吸指数 (PO2 / Fi O2 ,MRI)的变化。结果 :虽然 NIPPV 2 4 h内多数患者呼吸困难有不同程度缓解、心率 (HR)和呼吸频率 (RR)明显减慢 (P均 <0 .0 5 )、脉搏容积血氧饱和度 (Sp O2 )和 MRI显著升高 (P均 <0 .0 5 ) ,但死亡组患者从发病到 NIPPV治疗的平均时间明显晚于生存组患者 ,且死亡组患者经NIPPV2 4 h后 APACHE 、RR仍显著高于生存组 (P均 <0 .0 5 ) ;Sp O2 、MRI明显低于生存组 (P均 <0 .0 5 )。结论 :对重症 SARS患者而言 ,NIPPV是机械通气的选择方式 ,但它无法替代有创机械通气治疗。治疗 SARS时不能错过 NIPPV或有创机械通气治疗时机 ,且绝不能拘泥于现行的无创或有创通气指征。     

Noninvasive ventilation

Noninvasive positive-pressure ventilation (NPPV) is the delivery of mechanical-assisted breathing without placement of an artificial airway such as an endotracheal tube or tracheostomy. During the first half of 20th century, negative-pressure ventilation (iron lung) provided mechanical ventilatory assistance. By the 1960s, however, invasive (ie, by means of an endotracheal tube) positive-pressure ventilation superseded negative-pressure ventilation as the primarily mode of support for ICU patients because of its superior delivery of support and better airway protection. Over the past decade, the use of NPPV has been integrated into the treatment of many medical diseases, largely because the development of nasal ventilation. Nasal ventilation has the potential benefit of providing ventilatory assistance with greater convenience, comfort, safety, and less cost than invasive ventilation. NPPV is delivered by a tightly fitted mask or helmet that covers the nares, face, or head. NPPV is used in various clinical settings and is beneficial in many acute medical situations. This article explores the trends regarding the use of noninvasive ventilation. It also provides a current perspective on applications in patients with acute and chronic respiratory failure, neuromuscular disease, congestive heart failure, and sleep apnea. Additionally, it discusses the general guidelines for application, monitoring, and avoidance of complications for NPPV.     

Eight-month prospective study of 14 patients with hospital-acquired severe acute respiratory syndrome

OBJECTIVE: To define the clinical characteristics and clinical course of hospital-acquired severe acute respiratory syndrome (SARS). PATIENTS AND METHODS: This 8-month prospective study of 14 patients with hospital-acquired SARS in Taipei, Taiwan, was conducted from April through December 2003. RESULTS: The most common presenting symptoms in our 14 patients with hospital-acquired SARS were fever, dyspnea, dizziness, malaise, diarrhea, dry cough, muscle pain, and chills. Lymphopenia and elevated serum levels of lactate dehydrogenase (LDH) and C-reactive protein (CRP) were the most common Initial laboratory findings. Initial chest radiographs revealed various pattern abnormalities and normal results. Five of the 14 patients required mechanical ventilation. The need for mechanical ventilation was associated with bilateral lung involvement on the initial chest radiograph and higher peak levels of LDH and CRP. Clinical severity of disease varied from mild to severe. At 8 months after disease onset, patients with mild or moderate SARS had normal findings or only focal fibrosis on chest high-resolution computed tomography. However, bilateral fibrotic changes remained in the 4 patients who had recovered from severe SARS, 1 of whom had mild restrictive ventilatory impairment. One patient with severe SARS died; she was elderly and had other comorbidities. Five additional patients had reduced diffusing capacity. CONCLUSION: The clinical picture of our patients presenting with hospital-acquired SARS revealed atypical pneumonia associated with lymphopenia, elevated serum levels of LDH, rapid clinical deterioration, and lack of response to empirical antibiotic therapy. Substantially elevated levels of LDH and CRP correlated with severe illness requiring mechanical ventilatory support. In those receiving mechanical ventilation, pulmonary function was only mildly reduced at 6 to 8 months after acute illness, consistent with the natural history of acute respiratory distress syndrome due to other causes.     

A simple functional marker to predict the need for prolonged mechanical ventilation in patients with Guillain-Barré syndrome

Introduction  

Patients suffering from Guillain-Barré syndrome (GBS) may frequently develop an acute respiratory failure and need ventilatory support. Immune therapy using plasma exchange or immunoglobulins has modified the natural course of the disease and by decreasing the length of the plateau phase, may induce a rapid improvement in ventilatory function. However a substantial proportion of patients still require prolonged mechanical ventilation (MV) and tracheotomy. The present study was designed to search for simple functional markers that could predict the need for prolonged MV just after completion of immune therapy.