Thomas L Petty's lessons for the respiratory care clinician of today.

Because of the importance of his original contributions and their practical relevance today, Thomas L Petty (1932-2009) was arguably the most important physician in the history of respiratory care. As much as any single individual, he was responsible for the concept of intensive and multidisciplinary respiratory care. In the 1960s and 1970s, he made key observations and introduced pioneering therapies in the ICU and in the home. He was the first to describe and name ARDS and to show how to use PEEP to treat life-threatening hypoxemia. He was one of the first anywhere to organize a pulmonary rehabilitation program and to show the beneficial effects of long-term oxygen therapy in COPD. Dr Petty emphasized the importance of practical, hands-on respiratory care education for both physicians and non-physicians using a collaborative team approach. He targeted educational activities and practical resources specifically to patients, and he showed how researchers and clinicians could interact responsibly with innovators in industry to the benefit of both. His life and career provide 6 important lessons for respiratory clinicians today and in the future: (1) whatever their roles, RTs and other clinicians in this field need to be experts in its core areas, such as mechanical ventilation, ARDS, and COPD; (2) respiratory care is a team activity: every member is important, and all the members need to communicate well and work together; (3) education needs to be targeted to those in the best position to benefit the patient, including primary care providers and family members; (4) everyone in the field needs to understand the important role of the respiratory care industry and to deal with it responsibly; (5) it must never be forgotten that it is all about the patient; and (6) respiratory care should be exciting and fun.

Oxygen in respiratory care: a personal perspective from 40 years in the field.

Oxygen is necessary for all aerobic life, and nothing is more important in respiratory care than its proper understanding, assessment, and administration. By the early 1970s P(aO(2)) had become the gold standard for clinically assessing oxygenation in the body. Since the 1980s the measurement of arterial oxygen saturation by pulse oximetry has also been increasingly used as an adjunct to (but not a replacement for) P(aO(2)). Despite the desirability of measuring tissue oxygenation directly, no reliable and clinically relevant such measure has emerged. The 2 areas in which oxygen has proven most important in respiratory care are long-term oxygen therapy (LTOT) and the management of potentially life-threatening hypoxemia in acute respiratory failure. That LTOT improves survival in appropriately selected patients with COPD was demonstrated by multicenter studies published more than 30 years ago, and their original selection criteria have so far not been improved upon. Severe hypoxemia in acute lung injury and ARDS can be improved by ventilation with PEEP, and also in many patients by various adjunctive techniques and alternative support strategies. However, the latter measures have not brought clear improvements in survival or other patient-relevant outcomes. In addition, the original goals of "normalizing" arterial oxygenation with high tidal volumes and lung-distending pressures have required modification as appreciation for ventilator-related lung injury has emerged. High concentrations of inspired oxygen may play a role in such injury, but aggressive measures to reduce them in order to avoid oxygen toxicity-which dominated ventilator management in previous decades-have been tempered in the present era of lung-protective ventilation. Although some additions and modifications have emerged, much of what we understand today about oxygen in respiratory care is owed to the pioneering work of Thomas L Petty more than 40 years ago.

Obesity and COPD: associated symptoms, health-related quality of life, and medication use.

BACKGROUND: There is little data about the combined effects of COPD and obesity. We compared dyspnea, health-related quality of life (HRQoL), exacerbations, and inhaled medication use among patients who are overweight and obese to those of normal weight with COPD. METHODS: We performed secondary data analysis on 364 Veterans with COPD. We categorized subjects by body mass index (BMI). We assessed dyspnea using the Medical Research Council (MRC) dyspnea scale and HRQoL using the St. George's Respiratory Questionnaire. We identified treatment for an exacerbation and inhaled medication use in the past year. We used multiple logistic and linear regression models as appropriate, with adjustment for age, COPD severity, smoking status, and co-morbidities. RESULTS: The majority of our population was male (n = 355, 98%) and either overweight (n = 115, 32%) or obese (n = 138, 38%). Obese and overweight subjects had better lung function (obese: mean FEV(1) 55.4% ±19.9% predicted, overweight: mean FEV(1) 50.0% ±20.4% predicted) than normal weight subjects (mean FEV(1) 44.2% ±19.4% predicted), yet obese subjects reported increased dyspnea [adjusted OR of MRC score ≥2 = 4.91 (95% CI 1.80, 13.39], poorer HRQoL, and were prescribed more inhaled medications than normal weight subjects. There was no difference in any outcome between overweight and normal weight patients. CONCLUSIONS: Despite having less severe lung disease, obese patients reported increased dyspnea and poorer HRQoL than normal weight patients. The greater number of inhaled medications prescribed for obese patients may represent overuse. Obese patients with COPD likely need alternative strategies for symptom control in addition to those currently recommended.

Patient-ventilator interaction.

Patient-ventilator interaction has been the focus of increasing attention from both manufacturers and researchers during the last 25 years. There is now compelling evidence that passive (controlled) mechanical ventilation leads to respiratory muscle dysfunction and atrophy, prolonging the need for ventilatory support and predisposing to a number of adverse patient outcomes. Although there is consensus that the respiratory muscles should retain some activity during acute respiratory failure, patient-ventilator asynchrony is now recognized as a cause of ineffective ventilation, impaired gas exchange, lung overdistention, increased work of breathing, and patient discomfort. Far more common than previously recognized, it also predisposes to respiratory muscle dysfunction and other complications, leads to excessive use of sedation, increases the duration of ventilatory support, and interferes with weaning. Appropriate recognition and management of patient-ventilator asynchrony require bedside assessment of ventilator graphics as well as direct patient observation. Among currently available ventilation modes and approaches, none has been shown to be clearly superior to all the others with respect to patient-ventilator interaction, and strongly held preferences among investigators have led to controversy and difficulties in carrying out appropriate studies evaluating them. As a result, marked practice variation exists among different specialties as well as in different institutions and geographical areas. The respected authorities on mechanical ventilation who participated in this conference differed in the modes they preferred but agreed that proper understanding and use according to the individual patient's needs are more important than which mode is chosen. Conference participants discussed the determinants, manifestations, and epidemiology of patient-ventilator asynchrony, and described and compared several ventilation modes aimed specifically at preventing and ameliorating it. The papers arising from these discussions represent the most thorough examination of this important aspect of respiratory care yet published.

Impact of offering continuing respiratory care education credit hours on staff participation in a respiratory care journal club.

BACKGROUND: Journal clubs are employed by education and healthcare institutions to facilitate learning about study design, to teach critical reading of the literature, and to help trainees and practitioners keep abreast in their fields. Our respiratory care department initiated a journal club that was open to all respiratory therapists in the community. The articles were selected by the journal club coordinator and posted on the club's web site. However, attendance remained poor despite changes in venue, time, and day of the week. In Washington State, respiratory therapists are required to obtain continuing respiratory care education credits (CRCEs), so we hypothesized that offering American Association for Respiratory Care CRCEs for journal club attendance would increase participation. METHODS: We measured journal club attendance during the 8 months preceding and the 8 months following introduction of CRCE credit for journal club attendance. The journal club meetings were held during same time frame, on the same day of the week, and in the same geographic region during the pre-CRCE and CRCE periods. Advertising for the journal club was the same during both periods as well. RESULTS: Pre-CRCE attendance ranged from 5 to 8 persons per meeting (mean ± SD 6 ± 1 persons), and CRCE-period attendance ranged from 7 to 10 persons (mean ± SD 8 ± 1) (P = .01). CONCLUSIONS: Providing CRCE credits for attendance was associated with increased participation in our departmental journal club.

A porcine model for initial surge mechanical ventilator assessment and evaluation of two limited-function ventilators.

OBJECTIVES: To adapt an animal model of acute lung injury for use as a standard protocol for a screening initial evaluation of limited function, or "surge," ventilators for use in mass casualty scenarios. DESIGN: Prospective, experimental animal study. SETTING: University research laboratory. SUBJECTS: Twelve adult pigs. INTERVENTIONS: Twelve spontaneously breathing pigs (six in each group) were subjected to acute lung injury/acute respiratory distress syndrome via pulmonary artery infusion of oleic acid. After development of respiratory failure, animals were mechanically ventilated with a limited-function ventilator (simplified automatic ventilator [SAVe] I or II; Automedx, Germantown, MD) for 1 hr or until the ventilator could not support the animal. The limited-function ventilator was then exchanged for a full-function ventilator (Servo 900C; Siemens-Elema, Solna, Sweden). MEASUREMENTS AND MAIN RESULTS: Reliable and reproducible levels of acute lung injury/acute respiratory distress syndrome were induced. The SAVe I was unable to adequately oxygenate five animals with Pao2 (52.0±11.1 torr) compared to the Servo (106.0±25.6 torr; p=.002). The SAVe II was able to oxygenate and ventilate all six animals for 1 hr with no difference in Pao2 (141.8±169.3 torr) compared to the Servo (158.3±167.7 torr). CONCLUSIONS: We describe a novel in vivo model of acute lung injury/acute respiratory distress syndrome that can be used to initially screen limited-function ventilators considered for mass respiratory failure stockpiles and that is intended to be combined with additional studies to definitively assess appropriateness for mass respiratory failure. Specifically, during this study we demonstrate that the SAVe I ventilator is unable to provide sufficient gas exchange, whereas the SAVe II, with several more functions, was able to support the same level of hypoxemic respiratory failure secondary to acute lung injury/acute respiratory distress syndrome for 1 hr.

How to read a case report (or teaching case of the month).

Case reports are of minor importance in evidence-based medicine but can nonetheless make meaningful contributions to both knowledge and education. Although many traditional medical journals publish fewer case reports in this era of space constraints and preoccupation with Impact Factors, new Internet-based journals are appearing that focus exclusively on reports of individual cases. Given the variability of documentation, objectivity, and interpretation among the case reports now accessible by clinicians and trainees, it is important to be able to read them critically and to use the information they contain appropriately. This article discusses factors to consider in evaluating individual case reports, and provides a practical semi-quantitative scheme for assessing their potential validity and educational value.

Translating evidence into practice.

Appropriately designed and conducted research is necessary for improving patient care and optimizing health outcomes, but access to best evidence is not enough to make these things happen. In respiratory care, as in other fields, patients do not benefit as much as they should from research findings and evidence-based practice guidelines. Current standards for the diagnosis, staging, and management of chronic obstructive pulmonary disease are based in large part on the results of spirometry, yet most patients carrying this diagnosis have not had this test performed. Despite compelling evidence that it saves lives, reduces complications, and decreases costs in acute respiratory failure complicating chronic obstructive pulmonary disease, noninvasive ventilation is not used in a large proportion of such cases. Lung-protective ventilation for acute lung injury and the acute respiratory distress syndrome also increases survival, decreases complications, and is cost-effective, yet many patients who stand to benefit do not receive it. Clinicians may not be aware of practice guidelines or be familiar with their recommendations; they may not agree with the recommendations, or have insufficient expectation that management according to the guideline will work; they may consider the guideline too complicated or difficult to use in their own practices; patient-related factors may interfere; and changing established practice is often difficult. Overcoming these and other barriers to best practice is the focus of knowledge translation, which recognizes the need for involvement of every aspect of health care and seeks to integrate them effectively. This paper discusses the challenges faced by knowledge translation, provides examples of its successful application in respiratory care, and summarizes what needs to be done if the potential benefits of available evidence are to be realized for both individual patients and the health care system as a whole.

The physiology of dinosaurs: circulatory and respiratory function in the largest animals ever to walk the earth.

The cardiopulmonary physiology of dinosaurs-and especially of the long-necked sauropods, which grew much larger than any land animals before or since-should be inherently fascinating to anyone involved in respiratory care. What would the blood pressure be in an animal 12 m (40 ft) tall? How could airway resistance and dead space be overcome while breathing through a trachea 9 m (30 ft) long? The last decade has seen a dramatic increase in evidence bearing on these questions. Insight has come not only from new fossil discoveries but also from comparative studies of living species, clarification of evolutionary relationships, new evaluation techniques, computer modeling, and discoveries about the earth's ancient atmosphere. Pumping a vertical column of blood 8 m (26 ft) above the heart would probably require an arterial blood pressure > 600 mm Hg, and the implications of this for cardiac size and function have led to the proposal of several alternative cardiopulmonary designs. Diverse lines of evidence suggest that the giant sauropods were probably warm-blooded and metabolically active when young, but slowed their metabolism as they approached adult size, which diminished the load on the circulatory system. Circulatory considerations leave little doubt that the dinosaurs had 4-chambered hearts. Birds evolved from dinosaurs, and the avian-type air-sac respiratory system, which is more efficient than its mammalian counterpart, may hold the answer to the breathing problems posed by the sauropods' very long necks. Geochemical and other data indicate that, at the time the dinosaurs first appeared, the atmospheric oxygen concentration was only about half of what it is today, and development of the avian-type respiratory system may have been key in the dinosaurs' evolutionary success, enabling them to out-compete the mammals and dominate the land for 150 million years.

History and epidemiology of noninvasive ventilation in the acute-care setting.

Although noninvasive ventilation (NIV) was first used to treat patients with acute respiratory failure in the 1940s, the history of this mainstay of today's respiratory care armamentarium has mainly been written in the last 20 years. There is now a robust evidence base documenting the efficacy of NIV in exacerbations of chronic obstructive pulmonary disease, cardiogenic pulmonary edema, and acute respiratory failure in immunocompromised patients, and evidence in support of NIV in other settings, such as hypoxemic acute respiratory failure and the management of patients who decline endotracheal intubation, is accumulating rapidly. Efficacy as demonstrated in clinical trials does not necessarily translate to clinical effectiveness in practice, however, and important barriers need to be overcome if NIV is to realize for the average patient the potential it has shown in research studies. However, although the expansion of its use in everyday patient care has lagged behind the growth of its evidence base, an increasing number of studies document the steadily expanding use of NIV in the acute-care setting. This article reviews the history of NIV as applied in acutely ill patients and summarizes the studies of NIV outside the research setting during the last decade.

Tracheal rupture resulting in life-threatening subcutaneous emphysema.

We present a case of a patient with severe chronic obstructive pulmonary disease who developed dramatic mediastinal and subcutaneous emphysema, without pneumothorax, following a difficult intubation. Misdiagnosis of tracheal rupture as barotrauma from alveolar overdistention initially delayed intervention and caused persistence of subcutaneous emphysema. Despite efforts to minimize tidal volume and airway pressure, the large airway disruption and positive-pressure ventilation resulted in tension subcutaneous emphysema with near-fatal hemodynamic compromise, oliguria, and respiratory acidosis. Decompression with subcutaneous vents immediately reversed the life-threatening circulatory and respiratory compromise and stabilized the patient until surgical correction of the tracheal tear could be accomplished.

Clinical practice guidelines for chronic obstructive pulmonary disease: a review and comparison of current resources.

The first clinical practice guidelines (CPGs) for the assessment and management of patients with chronic obstructive pulmonary disease (COPD) were published 30 years ago. These and subsequent CPGs issued by professional societies and other groups prior to 2000 were consensus recommendations based on expert opinion and available studies, and they have been criticized for being inconsistent and not explicitly evidence-based. The Global Initiative for Chronic Obstructive Lung Disease (GOLD), a joint project of the National Heart, Lung, and Blood Institute and the World Health Organization, released the first of a new generation of rigorous, evidence-based COPD guidelines in 2001. Since that time several other CPGs, notably those developed jointly by the American Thoracic Society (ATS) and the European Respiratory Society (ERS), and by the British National Collaborating Center for Chronic Conditions and Institute for Clinical Excellence, have also become available. While previous COPD guidelines had different severity-grading systems and differed in their therapy recommendations, the new CPGs are remarkably consistent and have very few areas of clinically relevant discrepancy. All are available free via the Internet, provide for regular revision and updating, and include materials for patients and the public, as well as for health-care providers. Although the GOLD and ATS-ERS guidelines both have international authorship and are intended for worldwide use, implementation of many of their recommendations (such as the requirement for spirometry in diagnosis and staging, an escalating management scheme that includes expensive inhaled medications and pulmonary rehabilitation, and consideration for lung-volume reduction surgery) remains beyond the reach of many patients and health care systems.

Respiratory considerations in the patient with renal failure.

Lung and kidney function are intimately related in both health and disease. Respiratory changes help to mitigate the systemic effects of renal acid-base disturbances, and the reverse is also true, although renal compensation occurs more slowly than its respiratory counterpart. A large number of diseases affect both the lungs and the kidneys, presenting most often with alveolar hemorrhage and glomerulonephritis. Most of these conditions are uncommon or rare, although three of them--Wegener's granulomatosis, systemic lupus erythematosus, and Goodpasture's syndrome--are not infrequently encountered by respiratory care clinicians. Respiratory complications of chronic renal failure include pulmonary edema, fibrinous pleuritis, pulmonary calcification, and a predisposition to tuberculosis. Urinothorax is a rare entity associated with obstructive uropathy. Sleep disturbances are extremely common in patients with end-stage renal disease, with sleep apnea occurring in 60% or more of such patients. The management of patients with acute renal failure is frequently complicated by pulmonary edema and the effects of both fluid overload and metabolic acidosis. These processes affect the management of mechanical ventilation in such patients and may interfere with weaning. Successful lung-protective ventilation in patients with acute lung injury and renal failure may require modification of hemodialysis in order to combat severe acidemia. Hemodialysis-related hypoxemia, which was once believed to be the result of pulmonary leukostasis and complement activation, is explained by diffusion of CO2 into the dialysate, with concomitant alveolar hypoventilation in the process of maintaining a normal P(aCO2). Like acute lung injury, renal failure is a common complication of critical illness. An increasing body of evidence also supports the notion that the kidneys, like the lungs, are susceptible to injury induced as a result of positive-pressure mechanical ventilation.

Tracheostomy and weaning.

No hypothesis relating to respiratory care in the intensive care unit has proved more difficult to study in an objective fashion than the commonly held belief that tracheostomy hastens weaning from ventilatory support. Tracheostomy might facilitate weaning by reducing dead space and decreasing airway resistance, by improving secretion clearance, by reducing the need for sedation, and by decreasing the risk of aspiration. Available evidence indicates that dead space and airway resistance are in fact reduced, although whether the magnitude of these reductions explains the clinical observation of more rapid weaning after tracheotomy is less certain. Most of the data on this subject come from laboratory experiments and short-term physiologic studies on clinically stable patients, and the available evidence from clinical trials with weaning as a primary end point is scant. One large multicenter trial showed no advantage to early tracheotomy but demonstrated how difficult it is to get clinicians to manage their patients with regimens that go against their strongly held opinions. The most recent clinical trial found that percutaneous dilational tracheotomy performed in the first 2 days in patients projected to need > 14 days of ventilatory support greatly reduced ventilator and intensive care unit days, and decreased both the incidence of pneumonia and overall mortality, in comparison with tracheostomy done after day 14. Conducting such trials is difficult because of investigator and clinician bias, the inability to predict which patients will actually require prolonged mechanical ventilation, and several other factors discussed in this article. Tracheotomy probably does aid in liberating some patients from ventilatory support, but this may be as much from its effect on clinician behavior as from any physiologic impact.

Changing pattern of ventilator settings in patients without acute lung injury: changes over 11 years in a single institution.

STUDY OBJECTIVES: To determine whether the widely accepted concept of using lower tidal volume (Vt) values in patients with ARDS or obstructive lung disease has affected the pattern of ventilator settings in mechanically ventilated patients who do not have one of these conditions. DESIGN AND PATIENTS: We performed a retrospective chart review of all patients who had experienced out-of-hospital cardiac arrest and had received ventilatory support for > or = 1 day at a university-affiliated county hospital during the years 1990, 1991, 1992, 1995, 1998, 1999, and 2000. RESULTS: In 139 such patients, the mean final Vt values used on the first day of mechanical ventilation were 11.7, 12.4, 11.3, 9.6, 9.7, 9.2, and 9.8 mL/kg in those years, respectively. Multivariate analysis revealed that increasing year (beta-coefficient = -0.24; p = 0.001) and the presence of pulmonary edema (beta-coefficient = -1.2; p = 0.001) were independent predictors of the use of lower Vt values. Patients managed with a low Vt (ie, < 10 mL/kg; mean [+/- SD] Vt, 8.4 +/- 1.3 mL/kg) had a significantly higher incidence of atelectasis than the patients who were managed with traditional, larger Vt values (ie, > or = 10 mL/kg; mean Vt, 11.8 +/- 1.5 mL/kg) [61.1% vs 36.7%, respectively; p = 0.02]. Multivariate analysis revealed that the mean Vt used on days 1, 2, and 3 (<10 mL/kg or > or = 10 mL/kg) was the only predictor of the development of atelectasis during the first 3 days of mechanical ventilation (odds ratio, 0.33; p = 0.015). There was no difference in the incidence of pneumonia, the number of days spent receiving mechanical ventilation, Pao(2)/fraction of inspired oxygen ratio, or respiratory system compliance between the low Vt group and the traditional Vt group. CONCLUSION: Currently, physicians at our hospital use lower Vt values than they have in the past. This is associated with the increase in the incidence of atelectasis in the patients who received ventilation using low Vt values.

Case reports in respiratory care.

The information in a case report should be viewed cautiously in terms of generalization beyond the reported example. Appropriately written and interpreted, however, a case report can be a valuable contribution to medical knowledge and educational for both author and reader. This article discusses the essential components of a case report, important issues of patient confidentiality, and how authorship should be determined. It then describes 10 common pitfalls in case report writing. These are inexperience, insufficient documentation of the case, insufficient awareness of practice beyond one's own clinical setting, describing substandard care, illogical or unphysiologic intervention, poor focus of presentation and discussion, inappropriate manuscript format, poor writing, ineffective illustrations, and poor use of references. The article then presents 10 specific ways to avoid or deal with these pitfalls, with the aim of increasing the likelihood that a prospective author's manuscript will be accepted for publication. These ways include seeking appropriate assistance with writing, documenting the case as thoroughly as possible, and carefully justifying any new technique or intervention. Authors are urged to expend the time and effort required to prepare the manuscript properly, using the journal's guidelines and paying special attention to illustrations and references, and also to have the manuscript read by a local colleague before formal submission. After submission, authors should view the receipt of reviewers' comments and subsequent manuscript revision as necessary and positive steps toward successful publication.