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Biomedical subjects

John R Bach

Publications and source records attributed to John R Bach.

At least 19 recordsLinked to original sources
PubMed2006

Breathing intolerance index: a new indicator for ventilator use.

OBJECTIVES: The purpose was to study the efficacy of a proposed breathing intolerance index for justifying ventilator use by patients with pulmonary or chest wall diseases and to compare with values obtained from healthy controls. DESIGN: A total of 42 patients with lung/chest wall disease, including 11 ventilator users and 25 age-matched controls, were studied. The breathing intolerance index was defined as (Ti/Ttot) x (Vt/VC), where Ti = inspiratory time of one breath (in seconds), Ttot = total time of one breath (in seconds), Vt = tidal volume (in milliliters) at rest, and VC = vital capacity (in milliliters). A digital spirometer with custom computer software was used. RESULTS: The examinations were completed uneventfully. The mean breathing intolerance index values of the 25 healthy volunteers, the 31 nonventilator user patients, and the 11 users of nocturnal noninvasive positive-pressure ventilation were 0.050 +/- 0.009 (mean +/- standard deviation), 0.087 +/- 0.022, and 0.186 +/- 0.038, respectively. The breathing intolerance indices of the ventilator users were significantly greater (P < 0.0001) than those of the other nonventilator user groups, and there was no overlap in values. CONCLUSIONS: Ventilator users have a significantly higher breathing intolerance index than nonventilator users. The index may be useful for justifying ventilator use.

Adult↗
PubMed2006

Expiratory flow maneuvers in patients with neuromuscular diseases.

OBJECTIVES: To compare cough peak flows (CPF), peak expiratory flows (PEF), and potentially confounding flows obtained by lip and tongue propulsion (dart flows, DF) for normal subjects and for patients with neuromuscular disease/restrictive pulmonary syndrome and to correlate them with vital capacity and maximum insufflation capacity. DESIGN: A cross-sectional analytic study of 125 stable patients and 52 normal subjects in which CPF, PEF, and DF were measured by peak flow meter and vital capacity and maximum insufflation capacity by spirometer. RESULTS: In normal subjects and in patients, the DF significantly exceeded PEF and CPF (P < or = 0.001). For normal subjects, PEF and CPF were not significantly different. For patients with neuromuscular disease/restrictive pulmonary syndrome, the CPF significantly exceeded PEF (P < 0.05). No normal subjects but 14 patients had DF lower than CPF. Thirteen of these 14 had the ability to air stack (maximum insufflation capacity greater than vital capacity), indicating greater compromise of mouth and lip than of glottic muscles. For 14 of 88 patients, maximum insufflation capacity values did not exceed vital capacity, mostly because of inability to close the glottis (inability to air stack). Nonetheless, for 11 of these 14 patients, the DF were within a standard deviation of the whole patient group; thus, bulbar-innervated muscle dysfunction was not uniform. CPF and PEF correlated with vital capacity (r = 0.85 and 0.86, respectively), and with maximum insufflation capacity (r = 0.76 and 0.72, respectively). CONCLUSIONS: Measurements of CPF, PEF, and DF are useful for assessing bulbar-innervated, inspiratory, and expiratory muscle function. Care must be taken to not confuse them.

Adolescent↗
PubMed2005

High pulmonary risk scoliosis surgery: role of noninvasive ventilation and related techniques.

OBJECTIVE: There is little awareness among surgeons of the potential for noninvasive mechanical ventilation as an alternative to prolonged endotracheal intubation or tracheostomy for patients with neuromuscular scoliosis and ventilatory failure. These methods have not been reported for the perioperative management of scoliosis correction in patients with an inability to sustain their alveolar ventilation. METHODS: Five children with flaccid scoliosis secondary to muscular dystrophy or spinal muscular atrophy who had very high pulmonary risk were preoperatively trained in the use of noninvasive intermittent positive-pressure ventilation (IPPV) and mechanically assisted coughing prior to spinal fusion. RESULTS: All patients were extubated by the third postoperative day to noninvasive IPPV despite continuous ventilator dependence. No patient developed any postoperative pulmonary complications or required a tracheotomy. CONCLUSIONS: It is critical for the orthopedic surgeon to be aware of these noninvasive options to tracheotomy to decrease the tendency to avoid surgery for these otherwise high-risk surgical patients.

Adolescent↗
PubMed2004

Effect of lung mechanics on mechanically assisted flows and volumes.

OBJECTIVE: To correlate the air flows generated by mechanical insufflation-exsufflation as a function of pressure delivery in a lung model at two pulmonary compliance and three airway resistance settings. DESIGN: With each combination of pulmonary compliances of 25 and 50 ml/cm H2O and airway resistances of 6, 11, and 17 cm H2O/liter/sec, ten cycles of mechanical insufflation-exsufflation were applied using pressure deliveries of 40 to -40, 50 to -50, 60 to -60, and 70 to -70 cm H2O. The resulting peak exsufflation flows and volumes were recorded. RESULTS: In a multivariate analysis, the pulmonary compliance, airway resistance, and pressure delivery were all found to significantly affect exsufflation flows and volumes such that a decreased pulmonary compliance or an increased airway resistance produced a decrease in exsufflation flow and volume, whereas an increased pressure delivery produced greater exsufflation flow and volume. CONCLUSION: Although mechanical insufflation-exsufflation pressures of 40 to -40 cm H2O are generally adequate for most patients with normal lung compliance and airway resistance, higher settings are often required when compliance decreases, by obesity or scoliosis, and possibly when airway resistance is increased.

Airway Resistance↗
PubMed2004

Effects of mechanical insufflation-exsufflation on respiratory parameters for patients with chronic airway secretion encumbrance.

STUDY OBJECTIVES: To analyze the physiologic effects and tolerance of mechanical insufflation-exsufflation (MI-E) for patients with chronic ventilatory failure of various etiologies. DESIGN: Prospective clinical trial. SETTING: Rehabilitation unit of a university hospital. PATIENTS OR PARTICIPANTS: Thirteen patients with amyotrophic lateral sclerosis (ALS), 9 patients with severe COPD, and 7 patients with other neuromuscular disorders (oNMDs) with chronic airway secretion encumbrance and decreases in oxyhemoglobin saturation (Spo(2)). INTERVENTIONS: Pressures of MI-E of 15 cm H(2)O, 30 cm H(2)O, and 40 cm H(2)O were cycled to each patient, with 3 s for insufflation and 4 s for exsufflation. One application was six cycles at each pressure for a total of three applications. MEASUREMENTS AND RESULTS: We continuously evaluated respiratory inductance plethysmography (RIP) and Spo(2) during every application. Peak cough flow (PCF) and dyspnea (Borg Scale) were also measured before the first and after the last application. The technique was well tolerated in all patient groups. Median Spo(2) improved significantly (p < 0.005) in all patient groups. Median PCF improved significantly (p < 0.005) in the ALS and oNMD groups from 170 to 200 L/min and from 180 to 220 L/min, respectively, and dyspnea improved significantly in the patients with oNMDs and patients with COPD from 3 to 1 and from 2 to 0.75, respectively. Breathing pattern characteristics (RIP) did not deteriorate after MI-E in any patient groups. Inspiratory flow limitation significantly decreased at the highest MI-E pressures for the ALS group. CONCLUSIONS: Our results confirm good tolerance and physiologic improvement in patients with restrictive disease and in patients with obstructive disease, suggesting that MI-E may be a potential complement to noninvasive ventilation for a wide variety of patient groups.

Adult↗
PubMed2003

Pulmonary physical medicine interventions for elderly patients with muscular dysfunction.

The respiratory consequences of respiratory muscle impairment, with or without bulbar muscle weakness, usually involve inadequate ventilation and airway secretion encumbrance and may progress to respiratory failure. This article focuses on muscular dysfunction of the bulbar and respiratory musculature in elderly patients with neuromuscular diseases or central nervous system disorders. In addition, the article discusses application of pulmonary physical medicine principles for patients with predominantly restrictive pulmonary disorders caused primarily by muscular dysfunction. Diagnostic evaluation, respective clinical courses and responses to therapy, and the use of noninvasive ventilatory support outside of an acute care setting are also reviewed.

Aged↗
PubMed2003

Threats to "informed" advance directives for the severely physically challenged?

The neuromuscular diseases, such as infantile spinal muscular atrophy, Duchenne's muscular dystrophy, and amyotrophic lateral sclerosis, are widely considered to be terminal illnesses. However, as with many neuromuscular and neurologic diseases, morbidity and mortality are caused by dysfunction of inspiratory, expiratory, and bulbar musculature. This article will discuss how inspiratory and expiratory musculature can be supported by simple, noninvasive means that are rarely considered when, as with the general population, individuals with disabilities are counseled about advance directives. Failure to use noninvasive aids almost invariably results in respiratory failure, intubation, and tracheostomy or death. When noninvasive aids are available, invasive measures referred to in advance directives (eg, intubation) are often needed only temporarily. Yet, ill-informed patients are often advised to refuse intubation and die or to be intubated and left to decide whether to undergo tracheostomy for long-term ventilatory support. Further, despite severe disability, ventilator users with neuromuscular disease report normal life satisfaction. Health care professionals, on the other hand, tend to ignore the patient's life satisfaction and consider quality of life measures not designed for the disabled to justify withholding life-saving interventions. Advance directives, although sometimes appropriate for patients with irretractable pain and advanced cancer, are inappropriate for patients with severe disability because of muscle weakness, and virtually no patients are appropriately counseled about all therapeutic options.

Advance Directives↗
PubMed2003

Spinal muscular atrophy type 1 quality of life.

OBJECTIVE: To compare healthcare professionals' assessment of the quality of life of spinal muscular atrophy type 1 children with that of the care providers for the children. DESIGN: The care providers of all 53 surviving spinal muscular atrophy type 1 children managed in one neuromuscular disease clinic were sent Likert-scale surveys of six quality of life issues and ten polar-adjective pairs. The quality of life estimations were compared with those of 67 clinicians and with those of 30 parents considering their unaffected children. RESULTS: One hundred care providers from 46 out of the 53 families (87%) responded. Although the clinicians' mean estimate of the children's quality of life was 2.85 +/- 0.2/10, the care providers' estimate was 7.81 +/- 0.2/10 (P < 0.0001). The care providers also found life with the children to be satisfying (6.0 +/- 0.2/7), interesting (6.6 +/- 0.1/7), friendly (6.1 +/- 0.1/7), enjoyable (6.3 +/- 0.1/7), worthwhile (6.7 +/- 0.1/7), full (6.6 +/- 0.1/7), hopeful (5.9 +/- 0.2/7), and rewarding (6.4 +/- 0.1/7), and they estimated the children to be happy (8.5 +/- 0.2/10) and their lives worth living (9.6 +/- 0.1/10). However, 69 of 104 felt that their lives were hard rather than easy, and 56 of 104 reported feeling tied down rather than free. Although the effort they felt for raising the child was high (8.3 +/- 0.3 by comparison with 5 for an unaffected child), the burden they felt in doing so was not (5.8 +/- 0.3/5). When asked whether they would or would not recommend ventilator use, 31 clinicians (45.5%) indicated they would, 24 (36.4%) would not, and 12 (18.2%) chose not to respond to this question. Care provider responses did not differ significantly from the responses of the parents of unaffected children except for the easy/hard semantic differential (care providers, 3.80 +/- 1.75 controls, 5.27 +/- 1.14, < 0.001). CONCLUSIONS: Although there is a widespread perception that spinal muscular atrophy type 1 children have a poor quality of life, this perception is not shared by their care providers.

Adult↗
PubMed2003

Successful pregnancies for ventilator users.

This case series describes full-term pregnancies despite no autonomous ability to breathe due to poliomyelitis or ventilatory insufficiency due to severe kyphoscoliosis. Three women with postpoliomyelitis who were continuously dependent on noninvasive intermittent positive pressure ventilation and one woman who developed ventilatory insufficiency due to severe kyphoscoliosis became pregnant and delivered healthy, full-term babies. They had vital capacities of 240, 250, 280 (5% of normal), and 880 ml (14% of normal), respectively, when becoming pregnant. The up to continuous use of noninvasive intermittent positive pressure ventilation can permit the natural completion of pregnancies of women with little or no ability to breathe unaided.

Adult↗
PubMed2003

Noninvasive interface for transtracheal mechanical ventilation for patients with severe cervical spine deformity.

This article describes a custom-molded patient-to-ventilator interface that permits mechanical ventilation via a tracheostomy site for patients for whom tracheostomy tubes can not be used because of severe cervical deformity. The nocturnal delivery of intermittent positive-pressure ventilation resulted in normalization of oxyhemoglobin saturation and end-tidal CO2 and alleviation of symptoms of alveolar hypoventilation. Thermoplastic patient-ventilator tubing interfaces can be constructed to permit ventilatory assistance for patients with tracheostomies who can not use tracheostomy tubes.

Adult↗
PubMed2003

Prevention of pectus excavatum for children with spinal muscular atrophy type 1.

To demonstrate the elimination of pectus excavatum and promotion of more normal lung growth and chest wall development by the use of high-span positive inspiratory pressure plus positive end-expiratory pressure (PIP+PEEP), patients with spinal muscular atrophy type 1 with paradoxical breathing were placed on high-span PIP+PEEP when sleeping from the point of diagnosis of spinal muscular atrophy. Although the appearance of pectus excavatum is ubiquitous in untreated infants with spinal muscular atrophy type 1, after institution of high-span PIP+PEEP, pectus resolves and lungs and chest walls grow more normally. High-span PIP+PEEP is indicated for all infants diagnosed with spinal muscular atrophy who demonstrate paradoxical breathing for the purpose of promoting more normal lung and chest development.

Child↗