Gilbert E. D’Alonzo

Effect of Emphysema Severity on the Apnea–Hypopnea Index in Smokers with Obstructive Sleep Apnea

RATIONALE The presence of obstructive sleep apnea (OSA) in patients with chronic obstructive pulmonary disease (COPD) is referred to as the OSA-COPD overlap syndrome. While lung inflation has been shown to be an important factor in determining upper airway stability, its role in determining OSA severity in smokers, including those with emphysema, has not been evaluated. OBJECTIVES To evaluate the importance of lung inflation on OSA severity (apnea-hypopnea index [AHI]) in smokers with suspected OSA. METHODS Fifty-one smokers (18 males; mean [±SD] age, 59 ± 9 yr; body mass index [BMI], 32 ± 9 kg/m(2)) who were part of the Genetic Epidemiology of COPD (COPDGene) project were studied. Patients underwent a full-night polysomnography for suspected OSA. Other testing included spirometry and volumetric chest computed tomography (CT) for quantitative measurement of CT-derived percent emphysema and CT-derived percent gas trapping. MEASUREMENTS AND MAIN RESULTS For the group overall, there was evidence of obstructive airway disease by spirometry (FEV1, 1.4 ± 0.5 L, 58 ± 14% predicted) and emphysema by quantitative CT (CT-derived percent emphysema, 11 ± 13%; CT-derived percent gas trapping, 31.6 ± 24.1%). Twenty-nine (57%) of the patients had OSA (AHI, 18 ± 12 events/h). Patients with OSA had a higher BMI but were younger than those without OSA (BMI, 35 ± 9 kg/m(2) vs. 29 ± 7 kg/m(2), respectively [P = 0.007]; age, 56 ± 8 yr vs. 62 ± 9 yr, respectively [P = 0.01]). There was an inverse correlation between the AHI and the CT-derived percent emphysema and CT-derived percent gas trapping, both for the entire group (r = -0.41 [P < 0.01] and r = -0.44 [P < 0.01], respectively) and when just those patients with OSA were evaluated (r = -0.43 [P = 0.04] and r = -0.49 [P = 0.03], respectively). Multiple linear regression revealed that, in addition to CT-derived percent emphysema and CT-derived percent gas trapping, sex and BMI were important in determining the AHI in these patients. CONCLUSIONS In smokers with OSA, increased gas trapping and emphysema as assessed by CT are associated with a decreased AHI. Along with sex and BMI, these measurements may be important in determining the severity of OSA in patients with COPD and may offer a protective mechanism in patients with more advanced disease.

Treatment of sleep disordered breathing in congestive heart failure

In patients with congestive heart failure, sleep disordered breathing occurs commonly and is associated with an increased mortality. In addition to central sleep apnea (Cheyne–Stokes respiration), obstructive sleep apnea is more prevalent in patients with congestive heart failure than in the general population. As a result, a number of treatments have been investigated, with varying results. While many therapies may improve the severity of sleep disordered breathing, only positive pressure ventilation has been shown to improve cardiac function. Newer forms of positive pressure ventilation, such as adaptive servo-ventilation, appear to be even more effective at correcting central sleep apnea. Whether any of these treatments have an effect on transplant-free survival is presently unknown and awaits further study.

Management of Massive Pulmonary Embolism

Define massive pulmonary embolism (MPE). Understand the hemodynamic and pulmonary gas exchange abnormalities associated with MPE. Recognize the different treatment options available for patients with MPE.

Wegener’s Granulomatosis

Granulomatosis with Polyangiitis (GPA), formerly known as Wegener’s Granulomatosis, is a multisystem disease that predominantly involves the respiratory tract and the kidneys. The pathological hallmarks are necrotizing granulomatous lesions and vasculitis of small and/or medium vessels. It is difficult to diagnose because its presentation is similar to many common diseases such as upper respiratory tract infections, pneumonia, and asthma. Understanding the signs and symptoms, laboratory findings, and biopsy results are key to making the diagnosis of Granulomatosis with Polyangiitis. A heightened degree of clinical suspicion for this rare disease will often lead to the correct diagnosis.

Prophylactic Regimens in the Intensive Care Unit

Identify risk factors associated with the development of deep vein thrombosis and its consequence, pulmonary embolism. Understand the indications and contraindications for medical, mechanical, and inferior vena cava filter prophylaxis, and describe the available methods for each. Identify the major physiologic mechanism associated with stress-induced gastritis and ulceration, and identify the risk factors associated with this condition. Know the methods used for prophylaxis of stress-induced gastritis and ulceration and the potential complications of the medical therapies used for this condition. Identify the nosocomial infections common in the intensive care unit and the causative organisms responsible. Discuss the various risk factors associated with the development of iatrogenic or preventable infection in critically ill patients. Employ a variety of effective prophylactic regimens to nosocomial infection in the intensive care unit: healthcare/ventilator associated pneumonia (VAP), catheter-related bloodstream infection, and genitourinary tract infection in critically ill patients.

Critical Care Neurology

After studying this chapter, you should be able to: Recognize the signs and symptoms of selected neurologic conditions, and the approach to diagnosis. Discuss treatments used in selected neurologic conditions. Appreciate the diverse array of neurologic diseases that may be encountered in the intensive care unit. Recognize ethical aspects of selected neurologic disorders.

Endoscopy in the Intensive Care Unit

After studying this chapter, you should be able to do the following: Understand the indications for both respiratory and gastrointestinal (GI) endoscopy in critically ill patients. Describe the contraindications and potential complications that are associated with endoscopy and endosurgery.

The effect of theophylline on the chronobiology of inflammation in asthma

Asthma is an inflammatory disease of the airways. It appears that the inflammatory environment responds differently at night when the asthmatic patient should be asleep as compared to other times during the day. The reason for this difference is multifactorial and likely very complex. Sustained-release theophylline therapy has proven to be an antiasthmatic therapy with impressive efficacy for the control of asthma and nocturnal asthma, the latter especially if administered once-daily in the evening. In that theophylline is a “weak” bronchodilator, it is possible that theophylline works through non-bronchodilator anti-asthmatic mechanisms. Therefore, it may be that theophylline’s principal anti-asthmatic effects are antiinflammatory in character. Recent data suggesting that theophylline has certain immunomodulating properties opens a whole new area for clinical investigation with this medication, a therapy that is literally decades old. In that theophylline therapy is relatively low in cost and convenient to take, this new investigative challenge should be taken seriously.