USMLE RX Pulmo Notes

Lofgren Syndrome

A type of acute sarcoidosis Bilateral Hilar Lymphadenopathy + Poly Arthritis *(commonly ankles=> often leads to swelling)* + Erythema Nodosum Associated with a good prognosis,with > 90% of patients experiencing disease resolution within 2 years *Common in women of Scandinavian or Irish descent*

What chromosome is the gene that codes the CFTR gene located on?

Chromosome 7 Cystic (6 letters) ...7..... Fibrosis (8 letters)

What is the drug of choice for treating inhalational anthrax?

Ciprofloxacin is the DOC Doxycycline and Penicillin are also effective

All of the dimorphic fungi follow the rule "Mold in the Cold; Yeast in the Heat". Which is the exception?

Coccidioidomycosis It is a spherule (not yeast) in tissue (37*C)

Name some other drugs asides from aspirin that are most commonly associated w/ acute asthma

Coloring agents such as tartrazine, B-blockers, and sulfating agents. (RX)

Cystic Fibrosis and Contraction Alkalosis

Contraction alkalosis occurs whenever there is a loss in bodily fluid that does not contain HCO3- . In this setting, the extracellular volume contracts around a fixed quantity of HCO3- resulting in a rise in [HCO3-]. Dysfunctional CFTR gene in the sweat gland causes patients to release excessive sodium and chloride along with excess fluid. Sweat under normal conditions and in these patients contain very little bicarbonate. Contraction alkalosis occurs as a result. The volume contraction also causes a secondary hyperaldosteronism, leading to potassium wasting in the sodium and urine, resulting in hypokalemia

What is the most common lethal genetic disease in the Caucasian Population?

Cystic Fibrosis

Hypertonic Saline and Cystic Fibrosis

Cystic Fybrosis is characterized by a decrease in the surface fluid layer of respiratory and intestinal cells. Hypertonic saline increases this liquid layer by osmotically drawing water from inside the epithelial cells

What prenatal ultrasound findings are suspicious for cystic fibrosis?

Cystic fibrosis may be suspected on prenatal ultrasound if there is evidence of meconium peritonitis, bowel dilation, or absent gallbladder.

Nasal Polyps and Cystic Fibrosis

Cystic fibrosis should be suspected in a child with nasal polyps Polyps are usually secondary to repeated or chronic rhinitis, and are unlikely to form in children otherwise.

After you stabilize a patient with a tension pneumothorax, what intervention is still required?

After a needle decompression of a tension pneumothorax, the patient still needs a chest tube.

What is the primary agent used in the management of acute asthma flare?

Albuterol (B2-adrenergic receptor antagonist)

A 22 year old woman presents to the emergency room with complaints of shortness of breath, dizziness and tingling in her extremities. Her past medical history is unremarkable. She denies any history of blood clots in her family. She denies any recent long flight trips. She does not smoke. On examination, pulse is 110/min and respiratory rate is 26/min. She is afebrile and blood pressure is within normal limits. Pulse oximetry reveals 99% on room air. There are no physical abnormalities . A D-dimer level is 50µg/l . An electrocardiogram shows sinus tachycardia without ant ST-T changes. Chest x-ray is unremarkable. Which of the following is the most appropriate next step in management? A) Start Conazepam B) Re-breathing in to a paper bag C) Start Calcium Gluconate D) Re-assure and teach to deliberately slow down respiration E) Admit to ward and start high flow oxygen

Answer. D This patient is suffering an cute attack of Hyperventilation syndrome. Management includes exclusion of pathological conditions followed by reassurance and instruction on techniques to deliberately slow down the respiration. Hyperventilation syndrome is one of the common causes of dizziness in young woman. It presents with rapid breathing, chestpain, dizziness and tingling in the extremities and around the mouth. Rapid breathing results in respiratory alkalosis. Alkalosis causes cerebral vasoconstriction leading to dizziness. Tingling occurs due to reduced ionized calcium resulting from increased binding of calcium to albumin as a result of respiratory alkalosis ( Alkalosis increases negative charges on albumin resulting in increased bound calcium and reduced free, ionized calcium - hence, alkalosis produces tetany). HVS is a diagnosis of exclusion even in patients with a known history of HVS. The symptoms in HVS can resemble serious pathological states such as pulmonary embolism and cardiac disorders. Such disorders must be excluded first before the symptoms are attributed to HVS. Absence of risk factors, low d-dimer, normal chest x-ray and EKG excludes the possibility of any of these serious conditions in this young woman. Once these are excluded, patient should be reassured that the symptoms are secondary to rapid breathing and she should be taught techniques to deliberately slow down her respiration. This will result in improvement of symptoms. Choice A is incorrect. HVS can be associated with panic attacks and panic disorder. However, more than 50% cases of HVS can occur without panic attack. Often, patients with panic attacks have a long history of anxiety and recurrent panic attacks. The clues to diagnosing a panic attack are recurrent episodes with at least of one of such attack followed by persistent concern and anxiety about possible recurrence of such attack. Patient often reports intense fear of dying during the attack and concern about having a heart attack or even dying if such an attack recurred. Even if the patient had a history of panic disorder, she currently is experiencing hyperventilation and this should be adequately addressed before starting any treatment for panic disorder. *Choice B is incorrect. Re-breathing in to paper bag was an old technique to treat the acute attack by breathing in to a paper bag. The rationale of such technique is to increase the arterial CO2 ( Pco2) thereby, reducing cerebral vasoconstriction. This must not be recommended. This technique is often unsuccessful and studies have reported significant hypoxia and deaths with this method. It is important to understand that hyperventilation leads to alkalosis - the oxygen-hemoglobin dissociation curve is shifted to the left resulting in intense binding of hemoglobin to oxygen thereby, reducing O2 delivery to the tissues ( referred to as 'alkalotic O₂ clamping' or the 'Bohr effect') Hence, the tissues become relatively hypoxic. Further restriction of inspired o2 by rebreathing technique will worsen the tissue hypoxia and may be detrimental. *First step should focus on calming down the patient. After reassuring and attempts to deliberately lower the breathing, if the patient does not improve - a secondary cause should be sought and reinvestigated. Option C is incorrect. Calcium gluconate administration may transiently improve tetany and tingling but will not improve other symptoms such as dizziness and hyperventilation. In fact, the drop in the ionized calcium is because of alkalosis and attempts should be made to reverse alkalosis by reducing ventilation by deliberately slowing down the breathing. Option E is incorrect. Patient's oxygen saturation is 99% and work up failed to reveal any underlying serious pathological state behind her hyperventilation. She can be safely reassured and discharged once the symptoms improve.

Most common ocular finding in Sarcoidosis

Anterior uveitis is the most common ocular finding in sarcoidosis, and it presents as blurry vision, pain, and floaters.

High Altitude and Respiratory Alkalosis

Atmospheric oxygen (PO2) DECREASES => DECREASED Pao2 => INCREASED ventilation => DECREASED Paco2 => respiratory alkalosis => altitude sickness.

In addition to its antibacterial properties, what effect does azithromycin have in patients with cystic fibrosis?

Azithromycin is used in patients with cystic fibrosis to reduce lung inflammation.

What are primary inflammatory cells present in asthma vs COPD?

In COPD the predominant inflammatory cells are neutrophils, macrophages, and CD8+ (Tc1) lymphocytes whereas eosinophils, mast cells, and CD4+ (T helper 2 cell) lymphocytes predominate in asthma. *COPD: Neutrophils, macrophages, CD8 Asthma:Eosinophils, CD4 (TH2) *

Cystic Fibrosis and Gallstones

In cystic fibrosis problems with bile production can occur. This bile is dehydrated and more acidic than normal bile, and its flow into the small intestine is reduced. Dehydrated bile can collect in the gallbladder and produce gallstones, which can cause inflammation of the gallbladder and symptoms such as pain, fevers, nausea, and vomiting. If this occurs, the gallbladder may need to be removed. The liver is also affected by dehydrated bile that obstructs the bile ducts in the liver. These gallstones are often pigmented and made up of cholesterol*

What is the mechanism of action of ivacaftor in cystic fibrosis treatment?

Ivacaftor is CFTR modulator that enhances the opening of the CFTR ion channel. It is used to treat cystic fibrosis patients that harbor gating mutations in which the opening of the CFTR channel is impaired. The CFTR G551D mutation is an example of a gating mutation.

A patient is found to have asymptomatic sarcoidosis. What is the next best step in management?

Many patients with asymptomatic non-progressive sarcoidosis *do not require treatment and will have spontaneous remission* **VERIFY

An infant fails to pass her meconium for the first 48 hours of life. Hirschsprung's disease is ruled out. What is the most likely diagnosis?

Meconium ileus is highly concerning for cystic fibrosis. Thickened meconium clogs the intestinal tract leading to the *classic radiological finding of a microcolon distal to the obstruction.*

Why are the vast majority of men with cystic fibrosis infertile?

More than 95% of men with cystic fibrosis are infertile because of problems with sperm transport, though they are able to produce normal sperm (spermatogenesis is normal) It is very common in men with CF to have congenital bilateral absence of the vas deferens due to luminal obstruction by thick secretion early in life. Results in azoospemia (absence of sperm in the ejaculate)

N-Acetylcysteine and Cystic Fibrosis

N-Acetylcysteine, (Mucomyst) splits the disulfide linkages between mucoproteins, resulting in a decrease in mucous viscosity.

What is the mnemonic for remembering the disease processes associated with Eosinophilia?

NAACP Neoplasia Allergic processes Asthma Chronic Adrenal Insufficiency Parasites

Do macrolides alter the disease course if given during paroxysmal phase of pertussis?

NO Macrolides such as azithromycin or erythromycin may decrease bacterial shedding but do not alter the disease course if given during paroxysmal (severe coughing) stage. Macrolides can be used for the treatment of pertussis if given during the CATARRHAL stage

Inhaled Corticosteroids are an effective treatment for asthma and are associated with less side effects. However Inhaled Corticosteroids are associated with what oral complications?

Oral Candidiasis/ Thrush

Methylene chloride is a solvent commonly found in _____?

Paint Removers

Psammoma bodies are seen in?

Papillary adenocarcinoma of the thyroid Serous papillary cystadenocarinoma of the ovary Meningioma Malignant Mesothelioma PSaMMoma bodies

Nystatin

Same MOA as AMP B: Binds to ergosterol and forms pores that allow leakage of electrolytes *Too toxic for systemic use (Never given parenterally)* Nystatin may be used by mouth ("Swish and swallow) , in the vagina, or applied to the skin Used for Oral candidiasis, Vaginal Yeast infections, Diaper rashes *According to Fischer Notes, Nystatin swish and swallow is not sufficien to control Esophageal Candidiasis*

The horizontal fissure of the lung, which separates the _______ and ______ lobe, lies at the level of the (#)_______ rib anteriorly?

Separates upper and middle Horizontal Fissure: 4th rib

How do you treat a small (less than 3 cm) primary spontaneous pneumothorax that is not life threatening?

Stable patients with small primary spontaneous pneumothorax (<3cm) on imaging can be given supplemental oxygen & observed as most small pneumothoraces will resolve on their own.

In patients with cystic fibrosis, which microbe most commonly causes recurrent pulmonary infections in: - Infancy? - Adolescence?

Staphylococcus aureus in infants Pseudomonas aeruginosa in adolescents

Infertility vs Sterility

Sterility = it is impossible for a couple to conceive a child. A diagnosis of sterility is given after examination concludes that there is no sperm production and ovulation can't occur. Infertility = a couple is not sterile but for some reason has not been able to conceive a child. There are three conditions that must met for conception to be possible: 1) sperm must be present 2) the fallopian tubes must be open 3) ovulation must be able to occur. If one or more of these conditions is not met, the couple suffers from "true infertility."

What is the immediate management of a sucking chest wound?

Sucking chest wounds are those that visibly can be seen to suck in air, and can lead to a tension pneumothorax. Management is bandaging with an occlusive dressing *taped at only 3 points, which acts as a one-way valve to let air out of the thorax.*

In a tension pneumothorax, compression of ___________ by trapped air, causes increased venous pressure and JVD?

Superior Vena Cava

Presentation of Carbon Monoxide Poisoning

Symptoms *confusion *headache Physical exam *cherry-red skin (this is a rare finding) Chronic low-level exposure may cause flu-like symptoms *nausea *headache *myalgia Patients severely exposed to carbon monoxide typically present with: Neuropsych symptoms: *seizures *delirium Cardiology symptoms *myocardial ischemia *arrhythmias

Which tends to be more severe? Secondary or Primary Spontaneous Pneumothorax?

Symptoms in SSPs tend to be more severe than in PSPs, as the unaffected lungs are generally unable to replace the loss of function in the affected lungs.

Surfactant synthesis begins around week _____? Mature levels of surfactant are not achieved until week ____?

Synthesis begins week 26 Mature levels acheived after week 35

What are 2 reasons that women with cystic fibrosis have reduced fertility?

While women with cystic fibrosis have *anatomically normal genitourinary tracts*, some patients my have reduced fertility due to especially thick cervical mucus and ​amenorrhea (which can be secondary to nutrient deficiencies).

What is another name for Acid Fast Stain?

Ziel-Neelsen Stain

Describe the typical findings in a history of Carbon Monoxide Poisoining

automobile exhaust smoke inhalation barbecues old appliances in poorly ventilated locations gas/keroene heaters house fires *Methylene chloride ingestion* (converts to CO hepatically) (Methylene chloride is a solvent found in many paint removers)

A five year old Caucasian male with recurrent otitis media and sinusitis is found to have a higher that normal nasal transepithelial potential difference. Which of the following process most likely underlies this finding? a)Increase Chloride secretion. b)Increase Na absorption c)Intracellular K depletion d)Increase bicarbonate transport rate e)High mucous water content

b)Increase Na absorption

List some examples of normal tissues that are lined by stratified squamous epithelium?

skin mouth anus vagina esophagus

What are the chest x-ray findings in cystic fibrosis?

the chest x-rays of cystic fibrosis patients may show hyperinflation, bronchiectasis, cyst formation, and flattening of the diaphragms.

Whooping cough is characterized by coughs on inspiration and a whoop during expiration T/F?

F Coughs on Expiration Whoop on Inspiration "Whoop" is the sound used to describe the deep breath taken after a bout of coughs during expiration

Bouts of multiple coughs in a single breath followed by a deep inspiration is characteristic of Dyptheria T/F?

F The description is characteristic of Whooping Cough

Oral Candidiasis must be present if a patient has Esophageal Candidiasis T/F?

F Oral Candidiasis need not be present in Esophageal candidiasis. One does not automatically follow from the other.

When hemoglobin levels become less than 70%, oxygen saturation levels are less than 95% T/F?

F! *The hemoglobin content of the blood will never affect a patient's oxygen saturation levels. Saturation levels are always a reflection of oxygen's ability to get into the blood stream, not the amount of hemoglobin in the blood*

What is the first symptom that typically occurs as a result of CO poisoning? If the poisoning is severe enough to cause an acid base abnormality, what would it be most likely to cause?

Headache (usually the first symptom) Metabolic acidosis in severe poisoning (lactic acidosis due to end organ ischemia)

What is the triad of symptoms classically seen in Aspirin Induced Asthma?

1) Asthma 2) Chronic rhinosinusitis with *nasal polyps*, 3) Asthma and rhinitis attacks in response to aspirin and other NSAIDs

What is the classic triad of symptoms associated with Kartagener's Syndrome?

1) Bronchiectasis 2) Situs Inversus 3) Chronic Sinusitis

What is a spontaneous pneumothorax? How are the different types of spontaneous pneumothorax classified?

A spontaneous pneumothorax is *a pneumothorax that occurs without any inciting event (such as trauma).* There are two types of spontaneous pneumothorax that are classified based upon whether or not there is a known underlying lung disease.

Physical Exam findings of Tension Pnemothorax

A tension pneumothorax can present with all the signs & symptoms of a spontaneous pneumothorax, as well as SHOCK/HYPOTENSION and JVD due to compression of the superior vena cava.

Why is a Tension Pneumothorax considered to be a medical emergency?

A tension pneumothorax is a medical emergency because positive pressure in the pleural space displaces and compresses the other structures in the mediastinum (most notably cardiovascular structures). This can interfere with venous return to the heart, causing cardiovascular collapse and shock.

Primary vs Secondary Pneumothorax

A primary spontaneous pneumothorax (PSP) occurs in individuals with no known lung diseases. *In most cases, the affected individual has a previously unrecognized lung disease and the pneumothorax originates from the rupture of a subpleural bleb (aka bullae). The typical patient affected by a PSP is a tall male between the ages of 20 and 40 (a PSP is rare in individuals over 40).* *A secondary spontaneous pneumothorax occurs in individuals with lung disease (ex: COPD).​* Two of the most common cause of 2ndary Spontaneous Pneumothorax = CF and COPD (emedicine)

Situs Inversus

* complete left-> right reversal of all organs and blood vessels in the body *50% of individuals with Primary Cilia Dyskinesia present with Situs Inversus *most people with situs inversus have no medical symptoms or complications resulting from the condition *Situs Inversus incompletus is when the reversal is only limited to the heart and this is much more debilitating* * * * Normal CXR on right; Situs Inversus on left

A 10-month-old girl is brought to the physician by her father because she does not seem to be gaining weight despite an increased appetite. He says that she passes 8 to 10 stools daily. She has no history of major medical illness, but during the past winter she had several infections of the ear and respiratory tract that were treated with antibiotics. She appears malnourished but is in no apparent distress. She is at the 5th percentile for length and weight. Diffuse crackles are heard over the lower lung fields on auscultation. Her sweat chloride concentration is 69 mmol/L. Which of the following is the most likely underlying cause of these findings? (A) Abnormal cystic fibrosis transmembrane conductance regulator gene function (B) Acid phosphatase deficiency (C) Atypical conjugation of arylsulfatase A, B, and C (D) α-l-Fucosidase deficiency (E) Impaired production of phosphatidylcholine (lecithins)

(A) Abnormal cystic fibrosis transmembrane conductance regulator gene function

A 23-year-old man is seen in the ED for sud-den-onset, right-sided pleuritic chest pain that developed 30 minutes ago while he was watching television. The patient also complains of difficulty breathing. He has no prior medical history, denies smoking and intravenous drug use, and does not take any medications. His temperature is 37.3 °C (99.1°F), blood pressure is 130/82 mm Hg, pulse is 92/min and regular, respiratory rate is 20/min and shallow, and oxygen saturation is 98% on room air. He is 196 cm (6 ft 5 in) tall with a body mass index of 18 kg/m2 . Diminished breath sounds, hyperresonance, and decreased tactile fremitus are prominent in the right lung field. The trachea is midline. X-ray of the chest shows a 10% pneumothorax on the right. Which of the fol-lowing is the most appropriate initial manage-ment? (A) Observation with supplemental oxygen (B) Open thoracotomy with oversewing of the pleural blebs and scarification of the pleura (C) Needle decompression (D) Thoracoscopy with stapling of blebs (E) Tube thoracostomy with doxycycline pleurodesis

(A) Observation with supplemental oxygen *In Primary spontaneous pneumothorax the most appropriate initial management is Observation with supplemental oxygen.* The initial treatment for patients with pneumothoraces occupying > 15% of the hemithorax is Needle decompression The indications for thoracoscopy include failure of aspiration treatment, failure of lung reexpansion after 3 days of tube thoracostomy, persistence of bronchopleural fistula after 3 days, and recurrent pneumothorax after pleurodesis.

An 11-year-old girl with cystic fibrosis is admitted to the hospital 18 hours after the onset of shortness of breath. During the past 11 years, she has had more than 20 episodes of respiratory exacerbations of her cystic fibrosis that have required hospitalization. Current medications include an inhaled bronchodilator, inhaled corticosteroid, oral pancreatic enzyme, and oral multivitamin. Her temperature is 38°C (100.4°F), pulse is 96/min, respirations are 28/min, and blood pressure is 92/68 mm Hg. Diffuse wheezes and crackles are heard bilaterally. A sputum culture grows Burkholderia cepacia. Which of the following is the most likely cause of this patient's recurrent respiratory tract infections? (A) Immune suppression (B) Impaired clearing of airway secretions (C) Increased exposure to infectious organisms (D) Interstitial fibrosis (E) Restrictive changes of the small airways

(B) Impaired clearing of airway secretions

A 47-year-old man presents to your office complaining of progressively worsening episodes of shortness of breath. He has a history of asthma that has been well controlled with inhaled steroids, which he takes daily, and an albuterol inhaler, which he only needs to take approximately once to twice per month. He was hospitalized 6 weeks ago for new-onset stable angina and was discharged with sublingual nitroglycerine and low-dose aspirin, which he takes daily. Shortly after his discharge, he states that he began having increasing nasal and sinuscongestion, which soon progressed to episodes of wheezing, dry cough, and shortness of breath. He is now having these episodes about four times a week. In addition, he has had these symptoms at night three times in the past month. On physical examination, patient is afebrile, and lung examination reveals prolonged expiration with bilateral expiratory wheezes. He has nasal polyps. The peak expiratory flow is 85% of predicted. Which of the following would be the most appropriate management of this patient's condition? (A) Increased dose of inhaled steroids (B) Add a long-acting beta-agonist (C) Add theophylline (D) A short course of oral steroids tapering over 4 weeks (E) Add a leukotriene modifier

(E) Add a leukotriene modifier

Carbon Monoxide Poisoning

* * * * * *

Cystic Fibrosis and Pulmonary Manifestations

* *Bronchiectasis *Cor pulmonale

Cystic Fibrosis and Pancreatic Disease Biliary DIsease biliary cirrhosis?

****

Cystic Fibrosis

*AR *mutations in CFTR gene (chloride channel) on chromosome 7 *commonly a deletion of Phe508 *May appear at birth to years later * * * * * * * *Meconium Ileus is often the first sign of cystic fibrosis *Azoospermia and infertility are found in 95% of the males who survive to adulthood; congenital bilateral absence of the vas deferens

What immune cells stimulate the development of the granulomas characteristic of sarcoidosis?

*CD4+ T-helper cells* release cytokines which cause development of noncaseating granulomas.

What are the risk factors for hyponatremia in a patient with Cystic Fibrosis?

*Excessive breast/formula feeding *High temperature environments and exercise * * *

What bacteria commonly cause lung infection in cystic fibrosis patients?

*Haemophilus influenzae - common in early childhood *Staphylococcus aureus - common in early childhood *Pseudomonas aeruginosa - more prevalent later in life *Burkholderia cepacia

Sarcoidosis

*Idiopathic/no cause known *Multisystem disease characterized by noncaseating granuluomas in a variety of organs *Lungs most commonly involved organ *Smoking does NOT increase risk *Beryllium exposure very closely mimics *Many times asymptomatic and discovered incidentally when chest x-ray displays bilateral hilar lymphadenopathy *definitive diagnosis is based on lymph node biopsy *More common in African american females *Pulmonary function tests often display a RESTRICTIVE pattern* *Cardiac involvement of sarcoidosis can result in RESTRICTIVE cardiomyopathy.* *

Clinical Presentation of Sarcoidosis

*Many are asymptomatic and are diagnosed incidentally upon finding bilateral hilar lymphadenopathy on CXR *General feelings of malaise/fever/loss of appetite and weight loss *Chronic non productive cough * * * *

Meconium Ileus

*Meconium ileus is a bowel obstruction of the distal ileum due to an abnormally thick meconium. *In cystic fibrosis, the meconium can form a black-green mechanical obstruction in a segment of the ileum. *Below this level, the bowel is a narrow and empty *micro-colon*. *Above the level of the obstruction, there are several loops of hypertrophied bowel distended with fluid. *No meconium is passed, and abdominal distension and vomiting appear soon after birth * Often the first sign of cystic fibrosis*

Cromolyn

*inhibits mast cell degranulation and release of histamine. *due to short duration of action, requires 3-4 times dosing* *used only for asthma prophylaxis and is not effective during an acute episode *Adverse effects are minor and include cough, irritation, and unpleasant taste.

Desquamative Interstitial Pneumonia (DIP)

*primarily seen in smokers *no desquamation of alveolar epithelium is present *alveoli are filled with pigment laden macrophages *Much better prognosis than UIP with 10-year survival 70% to 100% * *

A 4-year-old Caucasian girl previously diagnosed with asthma presents with recurrent sinusitis, otitis media, and clubbing of the nail bed. Family history is significant for a distant cousin with cystic fibrosis. A "sweat test" is performed and comes back normal. What additional diagnostic test would be helpful in establishing a diagnosis? 1. Nasal transepithelial potential difference 2. Chest radiograph 3. Skeletal survey 4. Complete blood cell count 5. Urinalysis

1. Nasal transepithelial potential difference The clinical picture and family history is suspicious for a diagnosis of cystic fibrosis (CF). When a sweat test is negative, but clinical suspicion for CF is high, a useful diagnostic adjunct is a nasal transepithelial potential difference. The nasal transespithelial potential difference measures the voltage difference across the nasal epithelium, comparing the difference between charges on the respiratory epithelial surface and the interstitial fluid. *In individuals affected with CF, this measurement is significantly more negative than normal, due to increased luminal sodium absorption.*

In order of most severe to least severe, what are the three types of pneumothorax?

1. Tension pneumothorax 2. Secondary spontaneous pneumothorax 3. Primary spontaneous pneumothorax (*less severe than secondary because patients have better lung reserve*)

What is the major complication of a spontaneous pneumothorax?

A spontaneous pneumothorax can progress to a tension pneumothorax.

Pathogenesis of a Tension Pneumothorax

A tension pneumothorax occurs when the visceral pleura or parietal pleura are involved in *a tissue defect that forms a one-way valve that lets air into the pleural space (but not back out). This results in trapping of the air in the pleural cavity.*

What is the immediate treatment of a tension pneumothorax?

A tension pneumothorax should be treated immediately with a *needle decompression (aka needle thoracostomy)*.

What is the typical age of onset of Sarcoidosis

20-30 years

You are a surgeon serving in the military overseas. You are caring for patients on the front line. Suddenly you get a new admission transferred by helicopter. The patient is a 25-year-old male. He has been shot in the right lower chest and has been stable for the past two hours. He has been getting progressively more short of breath. Vitals reveal temperature 37 degrees Celsius, heart rate of 121, blood pressure of 100/70, respiratory rate 23, and oxygen saturation of 89% on room air. You hear diminished breath sounds on the right side. His oxygen saturation is dropping. A bedside x-ray is taken and reveals the following in Figure A.What is the next step in management? 1. Insert a chest tube 2. Place the patient on oxygen and insert a chest tube 3. Perform a needle thoracostomy 4. Obtain an arterial blood gas 5. Perform a thoracotomy

3. Perform a needle thoracostomy The patient presents with tension pneumothorax after a traumatic gun shot wound. The appropriate next intervention is needle thoracostomy. In tension pneumothorax, the key physical examination findings are similar to spontaneous pneumothorax: ipsilateral decreased breath sounds and hyperresonance to percussion. Tension pneumothorax usually occurs in the setting of trauma or lung infection and is a medical emergency. Air is able to enter the pleural space, but not exit, usually secondary to a ball-valve mechanism. This generates a persistently positive pleural pressure that increases thoracic pressure and impedes venous return. Clinically, this may present as tachycardia, elevated jugular venous pulse and hypotension. Tension pneumothorax requires emergent intervention with needle decompression followed by chest tube insertion, because left untreated, it will result in hemodynamic collapse. At times, CXR can be helpful to differentiate if clinical signs are otherwise absent, as extreme tracheal and mediastinal deviation to the contralateral side suggest tension pneumothorax.

A 57-year-old male reports feeling dizzy and nauseous for several days. He also states he has been experiencing intermittent headaches and complains that his "muscles ache all over." The patient lives alone. He states the only recent changes in his home environment are that his dog has been spending more time indoors since the weather has gotten colder recently. Physical exam is significant for a male appearing his stated age in mild distress. He states that he believes his skin color has become more flushed recently compared to normal, with an increased reddish hue distributed diffusely over his entire body surface. Which of the following diagnostic assessments would be most likely to confirm this patient's diagnosis? 1. Pulse oximetry 2. Serum lead level 3. Environmental allergen panel 4. Co-oximetry 5. Rapid Detection Influenza Test

4. Co-oximetry This patient's presentation of nausea, dizziness, myalgias, headache, and cherry-red skin on physical exam suggest carbon monoxide (CO) poisoning. *Levels of carboxyhemoglobin are assessed by co-oximetry.* *Diagnosis is made through high suspicion on history and physical exam in addition to carboxyhemoglobin levels greater than 5% in nonsmokers or 10% in smokers.*

A pneumothorax is defined as a collection of air in the __________

A pneumothorax is a *collection of air in the pleural space, between the lung and chest wall. *

A 1-year-old child who was born outside of the United States is brought to a pediatrician for the first time because she is not gaining weight. Upon questioning, the pediatrician learns that the child has had frequent pulmonary infections since birth, and on exam the pediatrician appreciates several nasal polyps. Genetic testing is subsequently ordered to confirm the suspected diagnosis. Testing is most likely to show absence of which of the following amino acids from the protein involved in this child's condition? 1. Histidine 2. Leucine 3. Lysine 4. Valine 5. Phenylalanine

5. Phenylalanine The most common mutation in cystic fibrosis is the 3-base pair deletion in the CFTR gene that removes phenylalanine at amino acid position 508.

What percent of individuals with Primary Cilia Dyskinesia present with Situs Inversus?

50%

A 6-year-old boy with cystic fibrosis is brought to the physician by his mother because his skin has been cool and clammy for 30 minutes. Earlier in the day, he had been playing outdoors, and the temperature was 99 F. When returning indoors, he was thirsty and restless. His blood pressure is 70/40 mm Hg, and pulse is 120/min. Examination shows dry mucous membranes. Serum sodium level is 128 mEq/L, and serum chloride level is 87 mEq/L. Which of the following is the most likely explanation for these findings? A) Excessive sweat electrolyte level B) Excessive sweat volume C) Excessive urinary output D) Excessive vasopressor secretion E) Inadequate sweat production

A) Excessive sweat electrolyte level

A 20-year-old man comes to the physician because of a 3-month history of occasional chest tightness with exertion and with cold exposure. He has no medical history except eczema and mild seasonal allergies. He takes no medications. His temperature is 37.0 C (98.6 F), blood pressure is 120/70 mm Hg, pulse is 73/min, and respirations are 13/min. Physical examination shows scattered wheezes bilaterally and a prolonged expiratory phase. Which of the following is the most appropriate medical management at this time? A. Albuterol B. Cromolyn sodium C. Inhaled steroids D. Ipratropium bromide E. Zafirlukast

A. Albuterol http://www.usmleforum.com/files/forum/2007/2/208910.php

What are the classic chest X-ray findings in sarcoidosis?

About 1/2 of all cases of sarcoidosis are asymptomatic and are found incidentally on chest x-ray (CXR). Classically, CXR reveals bilateral hilar adenopathy ("potato nodes") and interstitial infiltrates.

What is the leading cause of death in patients with Cystic Fibrosis?

According to RX, Pulmonary infection with alginate producing P.Aeruginosa is the leading cause of death in patients with CF

Shortened QT interval Sarcoidosis

According to RX, the shortened QT interval is a manifestation of hypercalcemia secondary to increased 1,25-dihydroxyvitamin D ADD MOREEE

A 25-year-old man with cystic fibrosis comes to the physician because of a 3-day history of fever, cough, and progressive shortness of breath. His temperature is 38°C (100.4°F), and respirations are 32/min. Bilateral crackles and rhonchi are heard on auscultation of the chest. A nutrient agar plate seeded with bronchial secretions grows an aerobic, oxidase-positive, gram-negative rod that forms slimy colonies and produces pyocyanin. The organism does not ferment lactose. Treatment with multiple appropriate antibiotics has not led to eradication of the causal organism. Which of the following is the most likely explanation for the persistent colonization of this patient by this organism? A) Bacteriophage superinfection B) Biofilm formation in the lower respiratory tract C) Overgrowth of acapsular strains D) Pyocyanin synthesis E) Synthesis of exotoxin A

B) Biofilm formation in the lower respiratory tract Pseudomonas bacteria in the lungs of patients with cystic fibrosis form colonies on a biofilm composed of a mucoid exopolysaccharide called alginate.

Which of the following abnormalities is associated with Cystic Fibrosis? A)Hyperkalemic Acidosis B)Hypokalemic Alkalosis C)Hypokalemic Acidosis D)Hyperkalemia Alkalosis

B)Hypokalemic Alkalosis

A 5 y/o boy is seen in the office because he has developed nocturnal cough and wheezing over the past two wks.He is started on inhaled albuterol, but this only partially relieves his symptoms.He has a history of atopic eczema and allergic rhinitis.What is the most suitable "Long Term" medication for further management of this child's condition? A-Oral Theophilline B-Inhaled sodium cromolyn C-Oral zafirleukast D-Oral prednisone E-Ipratropium inhalations

B-Inhaled sodium cromolyn Asthma accompanied by other allergic disorders like allergic rhinitis and eczema, mast cell stabilizers are the agents of choice

Bronchitis histologically displays mucus secreting gland hyperplasia or hypertrophy?

BOTH

Pathogenesis of Aspirin Induced Asthma

By inhibiting the COX pathway, aspirin diverts arachidonic acid metabolites to the LO pathway. This also leads to a decrease in the levels of prostaglandin (PG) E2, the anti-inflammatory PG, along with an increase in the synthesis of cysteinyl leukotrienes (LTs). *Imbalance between Prostaglandins and Leukotrienes* LT-modifying drugs are effective in blocking the bronchoconstriction provoked by aspirin and are used in the treatment of this condition.

An anxious young woman presents to the emergency department with an acute onset of severe abdominal pain. She states that she "partied a little bit last night" and consumed approximately 8 or 9 alcoholic drinks. She also admits to using diuretics to "lose water weight." Her stool is guaiac-negative, but she has periumbilical tenderness to palpation. An arterial blood gas study shows that her pH is 7.55 and her bicarbonate level is 21 mEq/L, with a partial pressure of carbon dioxide of 25 mm Hg. Her serum shows normal sodium chloride levels. Which of the following is the origin of her acid-base disturbance? A A build-up of unmeasured anions due to hepatic metabolism of alcohol B Electrolyte imbalance due to diuretic use C Hyperventilation secondary to pain and anxiety D Hypoventilation due to the respiratory depression caused by alcohol ingestion E Vomiting due to alcohol toxicity

C Hyperventilation secondary to pain and anxiety The correct answer is C. According to her lab data, this young woman has an acute respiratory alkalosis. Respiratory alkalosis is caused by a loss of CO2, which is balanced by an increased excretion of HCO3−. Hence, a low CO2 and low HCO3− level indicate respiratory alkalosis. The key to this question is to recognize that respiratory alkalosis can be caused only by an increase in ventilation, which can be caused by low oxygen (in high altitudes) or by sympathetic stimulation such as anxiety, panic attack, or pain. In this case, the patient is described as anxious and presents with severe abdominal pain, which is most likely the result of acute alcohol-induced pancreatitis. Both the anxiety and the pain could be causing her to hyperventilate. Answer A is incorrect. An increase in anions would be consistent with anion-gap metabolic acidosis. Metabolic acidosis is indicated by the presence of a low pH with a low plasma HCO3− and a low CO2, and an increased anion gap, measured by ([Na+] - [Cl−] - [HCO3−]), which is normally between 10 and 16 mEq/L. Answer B is incorrect. Diuretic use can cause metabolic alkalosis by volume contraction. This causes the kidney to compensate by reabsorbing sodium and excreting hydrogen ions. A metabolic alkalosis would present with elevated pH, elevated CO2, and elevated HCO3−. Answer D is incorrect. Hypoventilation causes a reduction in pH due to CO2 retention. This will lead to a respiratory acidosis with a low pH, a high CO2, and a high HCO3−. The compensatory mechanism for respiratory acidosis is an increase in HCO3− retention by the kidneys to normalize the pH. Answer E is incorrect. Vomiting causes a metabolic alkalosis secondary to the loss of acid and chloride from the stomach. If this were the cause, this patient's lab results would show a high pH, a high HCO3−, and (with respiratory compensation) a high CO2. The causes of metabolic alkalosis include vomiting, diuretic therapy, and chloride restriction. The compensation for metabolic alkalosis is hypoventilation.

A 16-year-old boy with cystic fibrosis is brought to the physician because of shortness of breath and ankle edema over the past 2 days. He is below the 5th percentile for height and weight. His temperature is 37°C (98.6°F), blood pressure is 130/80 mm Hg, pulse is 82/min, and respirations are 25/min and labored. Examination shows mild perioral cyanosis, jugular venous distention, and bilateral pitting ankle edema. There is mild right upper quadrant tenderness. S1 is normal, and S2 is increased. Which of the following is the most likely cause of this patient's symptoms? A) Decreased systemic arterial pressure B) Increased plasma colloid oncotic pressure C) Increased pulmonary vascular resistance D) Portal hypertension E) Reduced left ventricular ejection fraction

C) Increased pulmonary vascular resistance Cor Pumonale Explain

A 19-year-old man comes to the physician because of a 6-month history of two to three daily episodes of foul-smelling diarrhea, he has had a 9-kg (20-Ib) weight loss during this period despite adequate food intake. He has had a chronic cough, recurrent sinusitis, and recurrent pseudomonal bronchitis over the past 2 years. He appears thin and cachectic. Vital signs are within normal limits. There is hyperresonance to percussion of the chest. Diff use rhonchi are heard throughout all lung fields. An x-ray film of the chest shows hyperinflation of the lungs and chronic bronchiectatic changes in both upper lung fields. Which of the following is most likely to be decreased in this patient? A) Residual lung volume B) Serum bicarbonate level C) Sperm count D) Stool fat E) Sweat chloride

C) Sperm count More than 95% of men with cystic fibrosis are infertile because of problems with sperm transport, though they are able to produce normal sperm (spermatogenesis is normal) It is very common in men with CF to have congenital bilateral absence of the vas deferens due to luminal obstruction by thick secretion early in life. Results in azoospemia (absence of sperm in the ejaculate)

How does cystic fibrosis lead to right heart failure?

Progressive obstructive lung disease and hypoxia can eventually lead to chronic pulmonary hypertension and then to right heart failure in CF patients.

A 12-year-old boy presents with complaints of chronic cough and inability to keep up with his schoolmates during physical education class. The patient's mother states that he has just recovered from his fourth bout of pneumonia in the past 5 months. On examination, digital clubbing, hyperresonance to percussion, and basilar crackles are noted. The boy's sweat chloride concentration is 87 mEq/L. Which of the following agents would most likely serve to alleviate his chronic signs and symptoms? A. Dextromethorphan (PO) B. Ipratropium (aerosolized) C. N-acetylcysteine (aerosolized) D. Pentamidine (aerosolized) E. Vancomycin (IV)

C. N-acetylcysteine (aerosolized) The primary goals of treatment include thinning the mucus secretions, keeping the airways open, and treating recurrent infections. Thinning of mucus can be achieved with mucolytics such as N-acetylcysteine. N-Acetylcysteine, (Mucomyst) splits the disulfide linkages between these mucoproteins, resulting in a decrease in mucous viscosity. It is indicated as adjuvant therapy in the treatment of abnormal viscid or inspissated mucus secretions in CF, chronic lung disease, post-traumatic chest complications, and atelectasis secondary to mucus obstruction. Inhaled bronchodilators are used to open the airways. Furthermore, prednisone has been shown to increase pulmonary function and increase body weight. The definitive treatment is lung transplantation.

What is the normal, physiological action of CFTR in the body? Consider differences among tissue locations.

CFTR is a channel that has different actions depending on the site the cells are located. The actions are as follows: *Lungs and GI tract: Secretes Cl- Sweat glands: Absorbs Cl-* In the *lungs and GI* tract, failure of CFTR results in *retained* Cl- throughout cells in the epithelia. Na+ is absorbed to compensate, drawing water in and thickening mucus secretions. In the *sweat glands*, failure of CFTR results in *excess* Cl- (and therefore Na+) in the sweat.

CFTR

CFTR is an ATP-gated chloride channel talk about ncreased camp.

What are 3 reasons why tissue hypoxia occurs during CO poisoning?

Carbon monoxide poisoning causes tissue hypoxia as a result of a "triple whammy": 1)Hemoglobin (Hgb) can't bind to O2 because Hb has a much higher affinity for CO than O2 2)Hgb can't unload O2, because CO causes a left shift in the oxyhemoglobin dissociation curve 3)CO binds to cytochrome c oxidase, which disrupts oxidative phosphorylation at the tissues (with what already limited oxygen is delivered)

A 32-year-old fire fighter is brought to the emergency department by ambulance after sustaining major injuries while on the job. He was the first responder to a fire in a large apartment building and suffered severe inhalation burns. On physical exam the patient's skin and oral mucosa appear bright red, and the patient is disoriented and complains that he has difficulty seeing clearly. Which of the following is a characteristic of the most likely cause of his current condition? A) It can lead to metabolic alkalosis B) The first symptom is usually seizure C) It affects cellular respiration at the level of the TCA cycle D) It inhibits the electron transport chain E) It causes a right-shift in the O2 binding curve

D) It inhibits the electron transport chain The man in this vignette is showing signs of CO toxicity. His presenting symptoms include headache (which is usually the first sign), dyspnea, altered mental status and cherry red pigmentation of the skin. CO poisoning has dramatic effects on O2 levels in 3 major ways. It causes a left shift (not a right shift) in the O2 binding curve, making oxygen less likely to be delivered to tissue. It also competes with O2 for binding sites on hemoglobin, and binds to hemoglobin with 240 times higher affinity than O2. This means that CO will fill hemoglobin O2 binding spots instead of O2, which will thereby decrease O2 saturation. Finally, CO inhibits cytochrome c oxidase in the electron transport chain (it does not affect the TCA cycle). Hypoxia leads to metabolic acidosis, not alkalosis.

Dornase alfa (DNAse) and Cystic Fibrosis

Dornase alfa is ahighly purified solution of recombinant human deoxyribonuclease I (rhDNase), an enzyme which selectively cleaves DNA. Dornase alfa hydrolyzes the DNA present in sputum/mucus of cystic fibrosis patients and reduces viscosity in the lungs, promoting improved clearance of secretions

According to RX, what is the most common presenting symptom of Sarcoidosis?

Dyspnea

If there is a high level of clinical suspicion, how can the diagnosis of a pneumothorax be confirmed?

Diagnosis of a pneumothorax is usually highly suspected based on a thorough history and physical exam, and *can be confirmed with a chest x-ray.*

Name two agents that can be used to thin mucus in cystic fibrosis and compare their mechanisms

Dornase alfa (DNAse) : DNA degradation of mucus N-Acetylcysteine: splits the disulfide linkages between mucoproteins

An elderly couple present to the emergency room, the woman with headache and dyspnea, the man with headache, dyspnea, and dizzy spells. Their skin has a cherry-red discoloration. What set of the following findings would you expect from these two patients? A) Decreased SaO2, increased PaO2, left shifted oxygen binding curve B) Decreased SaO2, no effect on PaO2, right shifted oxygen binding curve C) Increased SaO2, increased PaO2, left shifted oxygen binding curve D) Increased SaO2, no effect on PaO2, right shifted oxygen binding curve E) Decreased SaO2, no effect on PaO2, left shifted oxygen binding curve

E) Decreased SaO2, no effect on PaO2, left shifted oxygen binding curve Of note, pulse oximetry may give falsely normal readings of O2 saturation since it is not able to distinguish between oxyhemoglobin and carboxyhemoglobin. Similarly, because carboxyhemoglobin reflects red light (like oxyhemoglobin), the mucous membranes and skin of patients with CO poisoning can appear "cherry red" on a physical exam. In reality, however, O2 saturation is markedly reduced. This will not have any affect on oxygen concentration in the blood, which is independent of hemoglobin binding of oxygen, and only depends on the ability of oxygen to diffuse through the pulmonary capillaries. The couple will thus have decreased oxygen saturation, normal PaO2, and a left shifted oxygen binding curve. It should also be remembered that CO binds to cytochrome oxidase of the ETC, and thus also causes lactic acidosis.

A 9-year-old boy is brought to the physician by his mother because of a 1 -year history of cough productive of mucoid sputum, wheezing, and shortness of breath with exertion. He has a history of recurrent upper respiratory tract and sinus infections since birth. He is at the 25th percentile for height and weight. The mother says that his younger sibling is beginning to develop similar problems. Physical examination shows mild clubbing of the fingers. Laboratory studies show markedly increased sweat chloride and sodium concentrations. A defect of which of the following in this patient's bronchial epithelium is most likely causing these symptoms? A) Adrenoreceptors B) Membrane receptors C) Nuclear receptors D) Protein regulation E) Protein structure

E) Protein structure The most common mutation in CF is a deletion of Phenylalanine at the 508th position which prevents proper folding of the nascent protein, so it is then targeted for proteasomal degradation rather than for transport to the plasma membrane.

A 13-year-old white girl with a past medical history of nasal polyps develops severe bronchoconstriction and wheezing after taking a large dose of aspirin, having mistaken it for a cold medication. After presenting to the emergency department, she is found to have a past history of aspirin allergy. Which of the following medications can be used effectively to stop the bronchoconstriction resulting from her aspirin allergy? (A) Cromolyn (B) Dopamine (C) Methylxanthines (D) Prednisone (E) Zileuton

E. Zileuton

While O2 is the mainstay of COPD treatment, why is it possibly dangerous to give high concentrations of oxygen to COPD patients with hypercapnia?

In healthy individuals, increase in PaCO2 stimulates the central recceptors and increases the ventilation to get rid of excess CO2, so, PCo2 is the major stimulator of respiration and even a slight chage into that will effect the respiration rate. Here, minor changes in O2 play less role. However, in prolonged hypercapnia such as in long standing COPD, this increase in PaCO2 ceases to stimulate the medullary respiratiory center and respiratory drive. In such pts, resp. is stimualted by hypoxia (low PaO2) is sensed by peripheral chemorecceptors. Rapid increase in the fraction of inspired O2 (in cases of O2 supplementation) will lead to respiratory failure in these pts. because they loose the resp. stimulation by low O2. In summary: in chronic hypercapnia, high conc O2 may suppress their respiratory hypoxic drive--> resp failure

In most cases of primary spontaneous pneumothorax how does the pneumothorax originate?

In most cases, the affected individual has a previously unrecognized lung disease and the pneumothorax originates from the rupture of a subpleural bleb (aka bullae).

What is the treatment of Carbon Monoxide Poisoning?

Initial treatment includes 100% oxygen, followed by hyperbaric oxygen if symptoms persist. The hyperbaric oxygen displaces carbon monoxide from hemoglobin.

How does the Nasal Transepithelial Potential change in patients with Cystic Fibrosis?

Patients with Cystic Fibrosis exhibit a more NEGATIVE transepithelial potential The nasal transespithelial potential difference measures the voltage difference across the nasal epithelium, comparing the difference between charges on the respiratory lumen and the interstitial fluid The negative transepithelial potential difference is due to increased luminal sodium absorption (less sodium outside + more sodium inside = larger potential difference).

What are the physical exam findings in a patient with a pneumothorax?

Physical exam typically reveals: *Unilateral absence of breath sounds *(on the affected side) *Hyper-resonant sounds upon percussion of the lungs* *Tachycardia* *Tachypnea* In some cases, a deviated trachea Venous congestion of the head/upper extremities (JVD) (in a tension pneumothorax) Symptoms typically include pleuritic chest pain, dyspnea

What medication is used to augment sweat chloride testing?

Pilocarpine Pilocarpine (a muscarinic agonist) is used to *induce sweating and augment the chloride sweat test.*

What is the most common cause of Ventilator Associated Pneumonia?

Pseudomonas Aeruginosa (RX)

What are the most common abnormal pulmonary function testing results for a patient with sarcoidosis?

Pulmonary function tests may demonstrate a restrictive pattern, however they can also be normal in some patients.

How does Sarcoidosis affect DLCO?

Reduced Diffusion **VERIFY

A 79-year-old male is admitted to the intensive care unit for severe hospital acquired pneumonia requiring positive-pressure mechanical ventilation. The nurse calls you to the bedside for the following vital signs: temperature 37 degrees Celsius, heart rate 120 beats per minute, blood pressure 70/50 mmHg, respiratory rate 12 (set by the ventilator), and oxygen saturation of 89% on while breathing a fraction of inspired oxygen of 0.7. On physical exam, you note absence of lung sounds on the right. Neck exam is similar to that seen in the patient in Figure A. Which of the following is true regarding this acute presentation? 1. The gold standard for diagnosis of the illness is CT with a PE protocol 2. Chest X-ray should be performed before any intervention is attempted 3. The patient should be immediately treated with needle thoracostomy 4. The next step in management is to order a serum D-dimer 5. Chest X-ray would show tracheal deviation towards the side of the lesion

Tachycardia, distended neck veins, hemodynamic instability and decreased breath sounds suggest tension pneumothorax in this patient on positive-pressure mechanical ventilation. Immediate needle thoracostomy is required to prevent possible progression to cardiac arrest. A pneumothorax is considered to cause tension when intrapleural pressure becomes high enough to compress the lung and mediastinal structures to a degree that causes clinically-signficant changes in oxygenation and hemodynamics. Causes of tension pneumothorax vary from mechanical ventilation/barotrauma to other forms of thoracic trauma. Clinically, patients will present with tachycardia, tachypnea, and hypotension secondary to decreased venous return (preload), which results from increased intrathoracic pressure. Physical exam may show distended neck veins, tracheal shift away from the lesion, decreased breath sounds on the affected side, hyperresonance to percussion, and ipsilateral chest-wall rise. High suspicion for pneumothorax in an unstable patient in the appropriate clinical setting warrants decompression of the pleural space with needle thoracostomy, even prior to imaging confirmation, as progression to cardiovascular collapse can be fatal.

A 16-year-old boy comes to the emergency department complaining of severe headache, dizziness, and difficulty concentrating. The patient has been working as a painter for the summer. He had been working in a well-ventilated bedroom, but he mistakenly spilled some paint remover on himself. About 2 hours later, he began developing a severe headache. He brought the paint remover with him and you look on the label and see that methylene chloride is listed as one of the solvents. His blood pressure is 110/80 mm Hg, pulse is 65/min, and respirations are 14/min. A neurological examination is normal. His lips are very red and there is evidence of cyanosis of his fingers. Pulse oximetry, however, shows an oxygen saturation of 100% on room air. An arterial blood gas shows a carboxyhemoglobin level of 42% by co-oximetry. The most appropriate next step in management is to A. administer methylene blue, intravenously B. begin continuous positive airway pressure ventilation C. give him hyperbaric oxygen therapy immediately D. give him 100% supplemental oxygen by non-rebreather mask E. intubate him and provide pressure support ventilation

The correct answer is C. This is a case of severe carbon monoxide poisoning from methylene chloride exposure. Methylene chloride is a solvent found in many paint removers and is readily absorbed through exposed areas of the skin. Once in the bloodstream, methylene chloride is metabolized in the liver and one by-product of its metabolism is carbon monoxide. Carbon monoxide poisoning typically presents with vague neurological complaints and history of exposure. In severe cases, carbon monoxide poisoning can lead to seizure, coma, or death. Cherry-red lips are a classical physical finding associated with this condition. A routine pulse oximeter cannot distinguish carboxyhemoglobin from normal hemoglobin. Carboxyhemoglobin levels must be measured by co-oximetry, which can detect the spectral differences between carboxyhemoglobin and hemoglobin. Treatment consists of administering 100% supplemental oxygen. Patients with carboxyhemoglobin levels greater than 40% require hyperbaric oxygen therapy to improve tissue oxygenation and reduce carboxyhemoglobin levels. Methylene blue (choice A) is the treatment of choice for severe methemoglobinemia. It has no use in carbon monoxide poisoning. Continuous positive airway pressure (choice B) can improve oxygenation by recruiting alveoli and stent open airways. It is useful in pulmonary causes of hypoxia, but does not treat the underlying carboxyhemoglobinemia. *For routine cases of carbon monoxide poisoning, 100% supplemental oxygen (choice D) is the treatment of choice. However, this patient has very high carboxyhemoglobin levels and requires hyperbaric oxygen treatment. * The patient is able to maintain his airway and breathe on his own. If there are more severe complications of carbon monoxide poisoning like seizure or coma, intubation (choice E) may be required.

How is the diagnosis of carbon monoxide poisoning confirmed?

The diagnosis of carbon monoxide poisoning is confirmed by CO-oximetry, which measures the amount of carboxyhemoglobin in the blood

What drugs are especially useful for aspirin-induced asthma?

The leukotriene receptor blockers 1. montelukast 2. zafirlukast Zileuton may also be helpful

How are the majority of cystic fibrosis cases initially detected in the US?

The majority of cystic fibrosis cases in the United States are now detected through newborn screening. All infants undergo initial screening, commonly using a serum immunoreactive trypsin (IRT) assay.

What is the most common genetic mechanism of CFTR failure in cystic fibrosis?

The most common genetic mechanism of CFTR failure in cystic fibrosis is *protein misfolding and subsequent absence of CFTR on the cell membrane*. CFTR is absent on the cell membrane because misfolding renders it *unable to exit the RER*.

Describe the Pathophysiology of Cystic Fibrosis

The most common mutation in CF is a deletion of Phenylalanine at the 508th position which prevents proper folding of the nascent protein, so it is then targeted for proteasomal degradation rather than for transport to the plasma membrane. CFTR is an ATP chloride conductance channel that also regulates other channels, most importantly being the sodium channel ENaC *ENac normally uptakes sodium from the lumen* The functions of CFTR are tissue specific and therefore the impact of a CFTR is also tissue specific **Respiratory, Intestinal Epithelium* *CFTR secretes Cl into the lumen *CFTR normally inhibits ENac* *In CF, there is decreased or loss of Cl secretion. Also CFTR no longer inhibits ENac and therefore sodium absorption is also increased *Result of increased sodium and chloride intraceullarly is increased passive water reabsorption *=>decreased surface fluid layer/dehydration and thickening of body secretions **Sweat Glands* *CFTR reabsorbs luminal Cl *CFTR normally augments ENac* *In CF, there is decreased reabsorption of sodium and chloride and production of hypertonic sweat

What is the most common mutation seen in cystic fibrosis?

The most common mutation is delta F508 (deletion of the three bases coding for phenylalanine, which is the 508th amino acid in the CFTR protein).

What is the most important test to diagnose Cystic FIbrosis?

The most important test to diagnose cystic fibrosis is sweat chloride testing. A normal sweat chloride test can rule out cystic fibrosis, while *a chloride concentration of greater than 60 mEq/L is diagnostic.*

2 Mechanisms by which a pneumothorax occurs

There are 2 ways this generally occurs: 1)Air enters the pleural space through the chest wall as a result of trauma 2)Air enters the pleural space from the lung parenchyma through the visceral pleura

Which direction is the trachea deviated in a tension pneumothorax?

Tracheal deviation is a critical clue to determining if a pneumothorax is tension or spontaneous. *In a tension pneumothorax, the trachea deviates away from the affected lung, due to increased pressure on that side.*

What are the the typical treatment modalities for Cystic Fibrosis?

Treatment of CF varies based on the specific mutation and severity of disease, but typically includes: Short-acting inhaled beta-2 agonists Inhalation of hypertonic saline Prophylactic antibiotics Chest physiotherapy Dornase alfa A high protein/high calorie diet Pancreatic enzyme replacement therapy

Name two Side Effects listed in First Aid that are associated with LABAs? (long acting beta agonists)

Tremor and Arrythmias

A needle decompresion is performed by placing a needle catheter at the bottom of the _______ intercostal space at the midclavicular line.

bottom of 2nd intercostal space This location avoids the intercostal nerves & vessels, as well as the subclavian vessels.

Congenital absence of the vas deferens is typical of CF and leads to ____________ (infertility/sterility)

infertility but not sterility

What is the normal FEV1/FVC Ratio?

normal FEV1 = 4 L normal FVC = 5 L normal ratio = 80%