Q&A: Investigating for Suspected Respiratory Failure

Respiratory failure is commonly defined as respiratory dysfunction resulting in abnormalities of oxygenation and/or carbon dioxide (CO2) elimination and is classified as either hypoxemic (type I) or hypercapnic (type II), or a combination of both. These distinctions are clinically important and have diagnostic and therapeutic implications.

Q&A: Complications Of Acute Respiratory Failure

Respiratory failure results from inadequate gas exchange by the respiratory system due to various causes, such that arterial oxygen, carbon dioxide or both are not maintained at normal levels resulting in hypoxemia, hypercapnia or both. Respiratory failure is classified as either Type 1 or Type 2, based on carbon dioxide levels, and can be either acute or chronic. Respiratory failure may result in altered mental status due to cerebral ischemia. The normal partial pressure reference values are: oxygen PaO2 more than 80 mmHg (11 kPa), and carbon dioxide PaCO2 less than 45 mmHg (6.0 kPa).

Q&A: Evaluation of Lung Function (Pulmonary Function Test)

Evaluation of pulmonary function is important in many clinical situations, both when the patient has a history or symptoms suggestive of lung disease and when risk factors for lung disease are present, such as occupational exposure to agents with known lung toxicity. The European Respiratory Society and the American Thoracic Society have published guidelines for the measurement and interpretation of pulmonary function tests (PFTs).

Q&A: Evaluation of Acute Breathlessness and Wheeze

Wheezing is a common manifestation of respiratory illness in adults. While wheezing typically brings to mind airway obstruction from bronchoconstriction or excessive mucus production and/or poor clearance due to asthma or chronic obstructive pulmonary disease (COPD), wheezing is also caused by a spectrum of other processes that cause airflow limitation. These processes may be present on their own or may coexist with asthma or COPD, contributing to difficult to control symptoms. When evaluating wheezing, it may be helpful to recall the adage, "All that wheezes is not asthma [or COPD]; all that wheezes is obstruction."

Q&A: Diagnosis of Progressive Weakness

Many patients who complain of weakness are not objectively weak when muscle strength is formally tested. A careful history and physical examination will permit the distinction between lassitude, motor impairment due to pain or joint dysfunction, and true weakness.

Q&A: Oral Glucose Tolerance Test Interpretation

Tests that can be used to screen for type 2 diabetes are measurement of fasting plasma glucose, a glycated hemoglobin (A1C or HbA1C), and a two-hour plasma glucose during an oral glucose tolerance test (OGTT). However, because of its inconvenience, OGTT is not commonly used for screening, except in pregnant women.

Q&A: Complications Of Coronary Angioplasty

Complications seen during percutaneous coronary intervention (PCI) include those related to cardiac catheterization and diagnostic coronary angiography, and those that occur as a consequence of the specific equipment (eg, wires) required for the intervention or the intervention itself (eg, distal embolization leading to myocardial ischemia).

Q&A: Pathophysiology Of Parkinson's Disease

Parkinsonism is a clinical syndrome presenting with any combination of bradykinesia, rest tremor, rigidity, and postural instability. The most common form of parkinsonism is Parkinson disease (PD), a chronic, progressive disorder caused by degenerative loss of dopaminergic neurons in the brain and characterized clinically by asymmetric parkinsonism and a clear, dramatic, and sustained benefit from dopaminergic therapy.

Q&A: Evaluation of Cerebral Ischaemia

The symptoms of brain ischemia may be transient, lasting seconds to minutes, or may persist for longer periods of time. Symptoms and signs remain indefinitely if the brain becomes irreversibly damaged and infarction occurs. Unfortunately, neurologic symptoms do not accurately reflect the presence or absence of infarction, and the tempo of the symptoms does not indicate the cause of the ischemia. This is a critical issue because treatment depends upon accurately identifying the cause of symptoms.

Q&A: Autonomic Receptors and Post-Receptor Mechanisms of Action

The autonomic nervous system regulates many of the internal organs through a balance of two aspects, or divisions. Along with the endocrine system, the autonomic nervous system is instrumental in homeostatic mechanisms in the body. The two divisions of the autonomic nervous system are the sympathetic division and the parasympathetic division. The sympathetic system is associated with the fight-or-flight response, and parasympathetic activity is referred to by the epithet of rest and digest. Homeostasis is the balance between the two systems. Most organs in the body are innervated by both divisions and usually they have antagonistic effects. For example, the heart receives connections from both the sympathetic and parasympathetic divisions. One causes heart rate to increase, whereas the other causes heart rate to decrease.

Q&A: Risk Factors for Nocardiosis Infection

Nocardia was first identified by Nocard in 1888 in bovine farcy. The first human disease was described by Eppinger in 1890. Nocardia is a gram-positive, branching, filamentous, weakly acid-fast bacterium. These organisms are not part of normal flora and are very rarely laboratory contaminants. Pathogenic Nocardia are members of the family Nocardiaceae, the aerobic Actinomycetes. Nocardia asteroides is the principal cause of nocardiosis in the United States (responsible for 80% of human infection). Nocardia is ubiquitous in the soil and decaying vegetables and is found worldwide.

Q&A: Guideline Management of Ring-Enhancing Lesions in Immunocompromised Host

The differentials for peripheral or ring enhancing cerebral lesions includes cerebral abscess, tuberculoma, neurocysticercosis, metastasis, glioblastoma, subacute infarct/haemorrhage/contusion, demyelination (incomplete ring), tumefactive demyelinating lesion (incomplete ring), radiation necrosis, postoperative change, lymphoma - in an immunocompromised patient, leukaemia, thrombosed aneurysm, and necrotising leukoencephalopathy after methotrexate.

Q&A: Ring Enhancing Brain Lesions in Immunocompromised Individuals

The differentials for peripheral or ring enhancing cerebral lesions includes cerebral abscess, tuberculoma, neurocysticercosis, metastasis, glioblastoma, subacute infarct/haemorrhage/contusion, demyelination (incomplete ring), tumefactive demyelinating lesion (incomplete ring), radiation necrosis, postoperative change, lymphoma - in an immunocompromised patient, leukaemia, thrombosed aneurysm, and necrotising leukoencephalopathy after methotrexate.

Q&A: Ring Enhancing Brain Lesions in Immunocompetent Individuals

The differentials for peripheral or ring enhancing cerebral lesions includes cerebral abscess, tuberculoma, neurocysticercosis, metastasis, glioblastoma, subacute infarct/haemorrhage/contusion, demyelination (incomplete ring), tumefactive demyelinating lesion (incomplete ring), radiation necrosis, postoperative change, lymphoma - in an immunocompromised patient, leukaemia, thrombosed aneurysm, and necrotising leukoencephalopathy after methotrexate.

Q&A: Drugs Causing Arrhythmia As Side Effects

An arrhythmia is any rhythm that is not normal sinus rhythm with normal atrioventricular (AV) conduction. Normal sinus rhythm originates from the sinus node in the upper portion of the right atrium. During sinus rhythm, the heart rate is in the normal range, the P waves are normal on the electrocardiogram (ECG), and the rate is stable.

Q&A: Examination Findings Following Chest Xray With Absent Lung Markings

Chest x-ray review is a key competency for medical students, junior doctors and other allied health professionals. Chest radiographs are frequently performed and a fantastic tool for making diagnoses of acute and chronic conditions, as well as acting as a tool for follow-up.

Q&A: Clostridium Difficile Toxin in Stool Following Watery Diarrhea

Clostridioides (formerly Clostridium) difficile is an important cause of treatment-associated diarrhea and one of the most common health care-associated pathogens. Its clinical manifestations range from asymptomatic colonization or mild diarrhea to fulminant disease characterized by ileus, toxic megacolon, hypotension, or shock. C. difficile infection is less common in children than adults, but the incidence of C. difficile infection in children is increasing.

Q&A: The Body's Response to Injuries and Infections (Innate Immunity)

Humans live in an environment teeming with micro-organisms and could not exist as a species without highly effective mechanisms of host defense. The innate immune system constitutes the first-line barrier, the rapid-response mechanism, to prevent microbial invasion. Its components are inherited from parent to child and directed against molecules expressed only by micro-organisms. These host defense components are evolutionarily ancient, found in all multicellular organisms, and expressed in humans as conserved elements (homologs) shared with other vertebrates and, in some form, with insects and plants.

Q&A: Clinical Conditions Associated With Aortic Stenosis

Aortic valve stenosis (AS) is the most common cause of left ventricular outflow obstruction in children and adults; less common causes are subvalvular or supravalvular disease. Surgical aortic valve replacement (AVR) and transcatheter aortic valve implantation (TAVI) are the only effective treatments for severe aortic stenosis. Recommendations for surgical valve replacement for AS are based upon comparisons of the natural history of patients with AS to outcomes after surgical AVR.

Q&A: Clinical Conditions Associated With Varicoceles

The spectrum of conditions that affect the scrotum and its contents ranges from incidental findings that require patient reassurance to acute pathologic events that necessitate expeditious diagnosis and treatment. The most common nonacute scrotal conditions include varicocele, hydrocele, epididymal cyst and spermatocele, testicular cancer, chronic epididymitis, and cryptorchidism.