Blue Boxes III

Question 1

rib dislocation

Answer 1

Displacement of costal cartilage from sternum (sternocostal joint).
From impact.

Interchondral joint displacement can occur with false ribs (8, 9, 10) and may damage diaphragm or liver, while leaving a lump at site of displacement.

Question 2

rip separation

Answer 2

Dislocation of costochondral junction between rib and anterior costal cartilage.
Causes rib to move superiorly over rib above.

Question 3

intercostal nerve block

Answer 3

local anesthesia of intercostal space.
Anesthetic injection between paravertebral line and the area of required anesthesia.
Dermatome overlap requires 2+ contiguous intercostal nerves to be blocked to achieve complete loss of sensation.

Question 4

pulmonary collapse

Answer 4

Normal lung remains distended even with open airways due to visceral pleura adhering to parietal pleura on inner surface of thoracic wall (negative intrapulmonary pressure).

Negative intrapulmonary pressure causes air to enter interpleural space if it is perforated. Surface tension between pleura will fail to hold lung in a distended state, causing collapse by its own elastic recoil (secondary atelectasis).

Collapsed lung will appear on radiography as a mediastinal shift toward affected side, with diaphragm elevation and narrowing of intercostal space.

Question 5

hemothorax

Answer 5

caused by damage to an intercostal or internal thoracic vessel, or from internal lung hemorrhage.

Question 6

pneumothorax

Answer 6

Caused by penetrating wound to parietal pleura, from rupture of a pulmonary lesion into the pleural cavity (bronchopulmonary fistula) or from fractured ribs tearing the visceral pleura.

Question 7

hydrothorax

Answer 7

caused by pleural effusion

Question 8

hemopneumothorax

Answer 8

can be seen by horizontal air-fluid interface on xray

Question 9

thoracentesis

Answer 9

Insert needle into pleural cavity to sample fluid or remove blood/pus.
With pt upright, fluid accumulates in costodiaphragmatic recess (9th intercostal space).
Insert needle along midaxillary line, angled superiorly to avoid piercing diaphragmatic parietal pleura and diaphragm above liver.

Question 10

chest tube

Answer 10

For draining severe hemothorax, pneumothorax, or hydrothorax.
Incision at 5th/6th intercostal space (nipple level) at midaxillary line for tube insertion.
Angle superiorly toward cervical pleura (cupola) for pneumothorax, or inferiorly (toward costodiaphragmatic recess for hydro/hemothorax.

Question 11

lung auscultation/percussion

Answer 11

Auscultation will assess airflow through the tracheobronchial tree.
Percussion will show if the tissue is air-filled (resonant sound), fluid-filled (dull sound) or solid (flat sound).

“Base of lung” may refer to inferoposterior part of inferior lobe, auscultated in T10 intervertebral space on the posterior thoracic wall.

Question 12

bronchoscopy

Answer 12

view down trachea to carina.
Carina can be distorted, posteriorly widened and immobilized by bronchiogenic carcinoma that has metastasized to tracheobronchial lymph nodes.
Aspirated objects tend to fall into right lung bc R bronchus is straighter, wider, more vertical.

Question 13

Cough reflex

Answer 13

Mucous membrane covering carina causing choking/coughing when solid objects or fluid come into contact, assisting in bronchial expulsion.

Question 14

mediastinal shifts

Answer 14

Transverse thoracic plane (divides superior/inferior mediastinum) does not shift with gravity, only the viscera do.

Question 15

mediastinal shifts: supine

Answer 15

Viscera spread horizontally, pushing them superiorly.
Aortic arch superior to transverse thoracic plane.
Tracheal bifurcation inferior to transverse thoracic plane.
Central tendon of diaphragm lies at xiphisternal junction (T9)

Question 16

mediastinal shifts: standing

Answer 16

Aortic arch transected by transverse thoracic plane.
Tracheal bifurcation inferior to transverse thoracic plane.
Central tendon of diaphragm lies at mid-xiphoid process (T9-10)

Question 17

widening of mediastinum

Answer 17

Common from trauma causing hemorrhage after great vessel laceration or from malignant lymphoma enlarging mediastinal lymph nodes.
Congestive heart failure (venous return rate > cardiac output) can cause myocardial hypertrophy, showing an enlargement of the inferior mediastinum.

Question 18

pericarditis

Answer 18

Inflammation to the pericardium causing chest pain, roughening of the serous pericardium causing a pericardial friction rub, audible on auscultation of the left sternal border.

Chronic inflammation can cause calcification or pericardial effusions (may cause cardiac tamponade) - non inflammatory effusions can resule from congestive heart failure (decreased cardiac output causes right cardiac hypertension

Question 19

cardiac tamponade

Answer 19

Heart compression due to pericardial effusion limiting cardiac output. Hemopericardium can result in status post-MI or after cardiac surgery causes rapid compression leading to circulatory failure, jugular venous distension (blood backup from SVC).
Pneumothorax can dissect CT, causing pneumopericardium.

Question 20

pericardiocentesis

Answer 20

Used to drain pericardial effusions to relieve cardiac tamponade.
Two methods of entry: (1) insert a needle thru 5th/6th intercostal space close to sternum with needle entering bare area made by cardiac notch of left lung.
(2) Insert a needle angled upwards thru infrasternal angle

Question 21

valvular heart disease: Stenosis

Answer 21

valve does not open fully.

Question 22

valvular heart disease: regurgitation

Answer 22

Valve does not close fully. Increases cardiac workload.
Reduces cardiac output.
Causes blood turbulence heart as murmurs and sometimes felt as thrills.

Question 23

mitral valve prolapse/insufficiency

Answer 23

Flaps extend back to LA during systole, allowing blood to regurgitate back to LA during LV contraction

Question 24

pulmonic valve stenosis

Answer 24

Valve cusps fuse forming a dome with a narrow opening, restricting RV outflow and causing RV hypertrophy

Question 25

Infundibular pulmonary stenosis

Answer 25

Underdevelopment of conus arteriosus (conical ouch formed by the upper left angle to the right ventricle before the pulmonary trunk) causes restricted flow to pulmonary artery.

Question 26

pulmonic valve incompetence

Answer 26

Valve lunules (edges of cusps) become inflexible, causing valvular insufficiency, allowing retrograde flow back to the RV during diastole.

Question 27

aortic valve stenosis

Answer 27

Commonly caused by degenerative calcification or rheumatic fever.
Causes LV hypertrophy.
Seen age >60.

Question 28

aortic valve insufficiency

Answer 28

Aortic regurgitation back to the LV causing a murmur and collapsing pulse (rapidly diminishing forcible pulse).

Question 29

coronary artery disease

Answer 29

Coronary occlusion, resulting in any of the following:
acute MI
coronary atherosclerosis
angina pectoris

Question 30

acute MI

Answer 30

Region of myocardium perfused by occluded coronary artery become infarcted, most commonly due to LAD stenosis, followed by RCA and Circumflex branch of the LCA.

Question 31

coronary atherosclerosis

Answer 31

Lipid deposition of arterial intima.
Causes slow stenosis with compensatory expansion of collateral arteries (often insufficient during exercise) leading myocardial ischemia and MI

Question 32

angina pectoris

Answer 32

Severe, constricting chest pain due to transient ischemia and MI that does not induce infarction.
Ischemia triggers limited anaerobic metabolism, causing lactic acid accumulation, that triggers pain response. Common with exercise, cold exposure, or stress.
Pain relieved by 1-2 min of rest or sublingual nitroglycerin to dilate coronary arteries.
Pain may radiate in T1/2/3 distributions.

Question 33

CABG

Answer 33

Coronary Artery Bypass Graft.
Grafting of a vein (great saphenous) or redundant artery (radial, internal thoracic) from the aortic arch (or proximal to the stenosis) to a point distal to the coronary stenosis.

Use of the internal thoracic artery does not require it to be detached entirely, it can simply be surgically anastomosed distal to the stenosis.

Question 34

coronary angioplasty

Answer 34

Percutaneous transluminal coronary angioplasty passes a catheter into the stenosed artery, inflating a balloon to flatten the plaque and stretch the vessel.
Thrombokinase can be injected to dissolve a thrombotic embolus.
After vessel dilation, a stent is placed to maintain luminal patency.

Question 35

cardiac referred pain

Answer 35

Afferent pain fibers run centrally in the middle and inferior cervical branches and thoracic cardiac branches of the sympathetic trunk to T1-T5 (especially on left side).
Angina carried by lateral brachial, lateral antebrachial cutaneous nerves with t2-T3 intercostobrachial nerves because T1-T3 carries the visceral afferent fibers for the coronary arteries.
Visceral referred pain transmitted by visceral afferent fibers which accompany sympathetic fibers, felt in the regions of distribution covered by the spinal root into which they enter.

Question 36

thoracic duct laceration

Answer 36

Thin walled, white/colorless alongside the azygous vein and feeding into the L venous angle commonly damaged during surgery in the posterior mediastinum.
Damage causes leakage of lymph/chyle into the thoracic cavity, causing chylothorax and requiring thoracentesis with possible ligation of the duct (rerouting flow to a point superior to ligature via the venous system).

Question 37

acending aorta aneurysm

Answer 37

The aorta is only reinforced with a fibrous pericardium at the beginning of the arch. The acending region more proximal to the heart is weaker, thus the high pressure in aorta during systole may cause an aneurysm.
Commonly presents as chest pain radiating to the back, and may exert pressure on the trachea, esophagus, and recurrent laryngeal nerve causing dysphagia and dyspnea.

Question 38

aortic corarctation

Answer 38

Stenosis of the aortic arch diminishing flow to the inferior parts of the body.
Commonly occurs at the ligamentum arteriosum, either before it (preductal coarctation) or after it (postductal coarctation).

Question 39

postductal coarctation

Answer 39

Allows good collateral circulation to develop between aorta proximal and distal to the coarctation via the intercal thoracic a, which causes enlargement of this artery and the intercostal arteries (visible on radiograph, causing rib notching)

Question 40

preductal coarctation

Answer 40

Congenital malformation that reduces flow to the lower part of the body, but does not develop good collateral circulation, causing poor lower body development and cyanosis.

Question 41

probe-patent foramen ovale

Answer 41

small opening in adult fossa ovalis.
Often clinically insignificant.
(osteum secundum defect)

Question 42

Cor trilocurlare biventriculatum

Answer 42

congenital absence of atrial septum

Question 43

sinus venosus defect

Answer 43

improper development of septum secundum, leaving an opening above the fossa ovalis.

Question 44

cor triloculare biatriatum

Answer 44

congenital absence of ventricular septum

Question 45

retroesophageal right subclavian artery

Answer 45

Right subclavian originates proximal and inferior to the left subclavian off the aortic arch, crossing behind the esophagus, causing dysphagia.

Question 46

persistent truncus arteriosus

Answer 46

Failure to form a trunoconal septum at all due to abnormal neural crest cell migration.
Includes ventricular septal defect (no membranous interventricular septum).
Causes mixing of oxygenated/deoxygenated blood.

Question 47

transposition of the great vessels

Answer 47

Due to failure of the truncoconal septum to spiral.
Causes left ventricle to empty into pulmonary circulation and the right ventricle to empty into systemic circulation, causing cyanotic heart disease.
Not immediately fatal if there is mixing of blood thru patent foramen ovale or ductus arteriosus.

Question 48

tetralogy of Fallot

Answer 48

Due to formation of truncoconal septum too far toward pulmonary (anterior) side of truncus arteriosus.

1) pulmonary stenosis: due to decreased size of pulmonary trunk, with enlarged aorta.
2) Ventricular septal defect: misalignment of truncoconal septum prevents fusion with muscular ventricular septum prevents fusion with the muscular ventricular septum, so no membranous ventricular septum forms.
3) Overriding aorta: aorta extends over right ventricle from the left ventricle.
4) Right ventricular hypertrophy: due to excess blood sent to RV from the higher pressure LV system.

The deoxygenated blood erroneously pumped into aorta from RV causes severe cyanosis.

Question 49

Variations of great a. (anomalies of branches off arch of aorta)

Answer 49

branches of arch of aorta

• could have L comm carotid originating of brachiocephalic trunk
• could have no formation of brachiocephalic trunk –> each of 4 a.s (R/L comm. carotid and subclavian a/) originate independently from arch of aorta
• could have L vertebral a. originating from arch of aorta
• could have retroesophageal R subclavian a. as last branch of arch of aorta (crosses posterior to esophagus to reach R upper limb –> dysphagia)
• could have an accessory a. to thyroid gland (thyroid ima a.) arising from arch of aorta or brachiocephalic a.

Question 50

Variations of great a. (anomalies of arch of aorta)

Answer 50

• sometimes arch curves over the root of the right lung and passes inferiorly on the right side, forming a right arch of the aorta
• arch could pass over root of R lung, pass posterior to esophagus to reach usual position on L.
• double arch (vascular ring around esophagus and trachea)