Wallach's Interpretation of Diagnostic Tests: Pathways to Arriving at a Clinical Diagnosis (570 page)

Suggested Readings

Clark B, Unsworth DJ. HLA and kidney transplantation.
J Clin Pathol.
2010;63(1):21–25.

Murphey CL, Forsthuber TG. Trends in HLA antibody screening and identification and their role in transplantation.
Expert Rev Clin Immunol.
2008;4(3):391–399.

Tait BD, Süsal C, Gebel HM, et al. Consensus guidelines on the testing and clinical management issues associated with HLA and non-HLA antibodies in transplantation.
Transplantation.
2013;95(1):19–47.

UNOS Policy.
http://optn.transplant.hrsa.gov/PoliciesandBylaws2/policies/pdfs/policy_7.pdf

UNOS, OPTN, Appendix D to Policy 3.
http://optn.transplant.hrsa.gov/PoliciesandBylaws2/policies/pdfs/policy_109.pdf

¹
The HLA Testing in Kidney Transplantation section was contributed by Neng Yu, MD.

Chapter
13

Respiratory, Metabolic, and Acid–Base Disorders

Lokinendi V. Rao and Michael J. Mitchell

Respiratory Disorders

Cough

Pulmonary Diseases Associated with Cough

Infectious Respiratory Diseases

Acute Bronchitis

Croup (Laryngotracheitis)

Pertussis (Whooping Cough)

Noninfectious Respiratory Diseases

Sarcoidosis

Upper Airway Cough Syndrome

Dyspnea

Pulmonary Diseases Associated with Dyspnea

Bronchiolitis

Legionella Infection (Legionnaires Disease)

Bacterial Pneumonia

Pneumocystis Pneumonia (PCP)

Viral Pneumonia

Tuberculosis

Noninfectious Pulmonary Diseases Associated with Dyspnea

Aspiration Pneumonia

Asthma

Cardiac Heart Failure

Chronic Obstructive Pulmonary Disease

Cystic Fibrosis

Pulmonary Embolism

Drug-Induced Pulmonary Diseases

Chemical Pneumonitis

Carcinoma of the Lung

Evaluation of Pleural Effusions

Rhinitis/Pharyngitis

Disorders of the Nose and Throat Associated with Rhinitis/ Pharyngitis

The Common Cold

Pharyngitis

Acute Rhinosinusitis

Diphtheria

Noninfectious Respiratory Disorders

Allergic Rhinitis

Acid–Base Disorders

Buffer Systems (Bicarbonate– Carbonic Acid)

Respiratory and Metabolic Systems in Acid–Base Regulation

Analyzing Acid–Base Disorders

Respiratory Alkalosis

Respiratory Acidosis

Metabolic Alkalosis

Metabolic Acidosis

Lactic Acidosis

Mixed Acid–Base Disturbances

Pearls

   
RESPIRATORY DISORDERS

Respiratory diseases include diseases of the lung, pleural cavity, bronchial tubes, trachea, and upper respiratory tract and diseases of the nerves and muscles of breathing. These conditions range from mild and self-limiting such as the common cold to life threatening such as bacterial pneumonia or pulmonary embolism. The symptoms of respiratory disease differ depending on the disease. Common symptoms are cough with or without the production of sputum, hemoptysis, and dyspnea, which usually occurs with exercise, chest pain, noisy breathing (either wheeze or stridor), somnolence, loss of appetite, weight loss, cachexia, and cyanosis. In some cases, respiratory disease is diagnosed in the absence of symptoms during the investigation of another disease or through a routine check.

Respiratory diseases can be classified in many different ways: by the organ involved, by the pattern of symptoms, or by the cause of the disease.

   
Obstructive lung diseases
are diseases of the lung in which the bronchial tubes become narrowed, making it difficult to move air in and especially out of the lung.

   
Restrictive lung diseases
(also known as interstitial lung diseases) are a category of respiratory diseases characterized by a loss of lung compliance, causing incomplete lung expansion and increased lung stiffness.

Respiratory tract infections can affect any part of the respiratory system. They are traditionally divided into upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs). The most common URTI is the common cold. However, infections of specific organs of the upper respiratory tract such as sinusitis, tonsillitis, otitis media, pharyngitis, and laryngitis are also considered URTIs.
Streptococcus pneumoniae
is the most common cause of severe, community-acquired bacterial pneumonia. Worldwide, TB is an important cause of pneumonia, usually presenting as a chronic infection. Other pathogens such as viruses and fungi can cause pneumonia, for example, severe influenza and
Pneumocystis
pneumonia. Tumors of the respiratory tract are either malignant or benign. Benign tumors are relatively rare causes of respiratory disease. Malignant tumors, or cancers of the respiratory system, particularly lung cancers, are a major health problem responsible for 15% of all cancer diagnoses and 29% of all cancer deaths. The majority of respiratory system cancers are attributable to smoking tobacco.

There are a wide range of symptoms due to the intrathoracic effects of various respiratory diseases, the most common of which are dyspnea, cough, and infections.

COUGH

Cough is a forced expulsive maneuver, usually against a closed glottis and which is associated with a characteristic sound. It is a natural respiratory defense mechanism to protect the respiratory tract and one of the most common symptoms of pulmonary disease. Most cases of troublesome cough reflect the presence of an aggravating factor (asthma, drugs, environmental, gastroesophageal reflex, upper airway pathology) in a susceptible individual. A cough can be classified by its duration, character, quality, and timing and is somewhat arbitrary. A cough lasting <3 weeks is termed “acute,” between 3 and 8 weeks is “subacute,” and one lasting >8 weeks is defined as “chronic.”

   Acute Cough

Acute cough is defined as a cough lasting <3 weeks. Most frequently, it presents in primary care settings and is commonly associated with URTIs. In most cases, it is benign and self-limiting and most commonly related to virus induced, postnasal drip, throat clearing secondary to laryngitis or pharyngitis. It is frequently associated with acute exacerbations and hospitalizations with asthma and COPD. Symptoms associated with acute cough that require further investigation include hemoptysis, breathlessness, fever, chest pain, and weight loss. Common serious conditions presenting with isolated cough include neoplasms, infections (e.g., TB), foreign body inhalation, acute allergy–anaphylaxis, and interstitial lung disease.

   Subacute Cough

Subacute cough is defined as a cough lasting 3−8 weeks. The gray area between 3 and 8 weeks of cough is difficult to define etiologically, since all chronic cough will have started as acute cough, but the diagnostic group of chronic cough is diluted by the patients with postviral cough (a URTI cough lingering for >3 weeks). Cough after infection is the most common cause of subacute cough (48%), postnasal drip is the second most common (33%), and cough variant asthma is the third most common (16%). In a significant percentage of patients, subacute cough (34%) is self-limited and will resolve without treatment. Most patients with subacute cough that spontaneously resolves had a postinfection cough.