Lecture 6 Flashcards
Pleural Space Disease
Pneumothorax* = air Chylothorax* = lymph Pyothorax* = pus Hemothorax = blood Hydrothorax = "water" - pure transudate Diaphragmatic hernia = organs
Radiographic signs of pleural effusion
- Gravity dependent soft tissue opacity
2. Fissure lines in the lungs
Pleural space
- Pleura: thin layer of mesothelial cells
- visceral pleura covers lung surface
- parietal pleura lines thoracic wall, diaphragm, mediastinum
- small amount of fluid between layers normally (helps lungs expand when thorax expands)
- Pleural fluid volume determined by:
- Starling’s forces (hydrostatic and oncotic pressure)
- Lymphatic drainage
- Mesothelial cells
Potential pleural effusion mechanisms
- Increased venous hydrostatic pressure (ie. CHF, thrombosis)
- Decreased oncotoic pressure
- Impairment of lymphatic drainage (increased venous pressure, lymphatic trauma, neoplasia, lung lobe torsion)
- Increased vascular permeability
Pleural effusion: physical exam
Pattern of dyspnea:
- RESTRICTIVE
Auscultation
- Muffled ventrally (gravity dependent fluid)
Pneumothorax: muffled dorsally, echo-like (air bubble rises)
Pleural Effusion: other physical exam parameters
- Other cardiopulmonary abnormalities (including jugular pulses)
- Thoracic compression (ie. cat mediastinal mass)
- Peripheral LN
- Abdominal palpation: masses, pain, ascites
- Fever
- Mucous membranes
- Cranial nerves (space occupying mass putting pressure on nerves causing Horner’s syndrome)
- BCS/muscle condition
Pleural Effusion (first step)
- Respiratory distress?
==> Yes = thoracocentesis
==> No = Thoracic imaging, minimum database
Thoracocentesis
- Sternal (ideal, not required; gravity dependent fluid will be symmetrical)
- Insert
- ~7-9th intercostal space- Air: aim for 2/3rd the way up between CCJ and spine
- Fluid: may need to aim closer to CCJ
- Insert needle in front of rib (vessels and nerves lie caudal to ribs!!)
- Ultrasound-guidance helpful for effusions
(often you can make a patient feel a lot better by just tapping one side)
Thoracocentesis
- Insert needle bevel up
- W/ needles:
- Once in chest, raise hand UP (allows needle to rest against body wall w/ bevel OUT - allows fluid to be pulled in)
Thoracocentesis: volume removed
- Save samples of effusion
- Note total volume removed
- EDTA tube: preserves cell morphology for cytology
- Red top: various biochemical tests
- Culture tubes (aerobic and anaerobic)
- +/- PCV if hemorrhagic (if peripheral PCV is same as effusion PCV, indicates bleeding into pleural space - hemothorax)
Effusion Classification
- Transudate
- Protein ~0.0 g/dL
- TNCC < 2500/uL
- Modified transudate
- Protein ~2.5 g/dL
- TNCC ~2500 - 5000/uL
- Exudate
- Protein > 5 g/dL
- TNCC > 5000/uL
Pleural effusion: transudates
Transudates:
1. Low protein, low cellular pleural fluid
2. Usually caused by low oncotic pressure
- Hypoalbuminemia
DDx: Hepatopathy (decreased liver function), PLE, PLN
3. *Or increased hydrostatic pressure from early heart failure
- Over time the heart failure transudates turn into modified transudates
Pleural effusion: modified transudates
Modified transudates
- Transudates that have been “modified” by the addition of: cells, protein, and/or chyle
- Right sided heart failure, pericardial disease
- Neoplasia (lymphoma, mesothelioma, carcinoma, etc)
- Chylothorax
- Lung lobe torsion
- Idiopathic
Pleural effusion: exudates
Exudates:
- High protein, high cellular effusions
- Predominant cell type depends on underlying cause
- Infectious (bacterial, fungal)
- Neoplasia
- FIP
- Chylothorax
- Lung lobe torsion
Biochemical tests
- Triglycerides
- Definitive dx of chylothorax: fluid TG > serum TG
(chyle = fat and WBC’s)
- Definitive dx of chylothorax: fluid TG > serum TG
- Glucose
- Low in septic effusions
- pH
- Low in septic effusions
Thoracic imaging
- Radiographs
- Confirm pleural effusion (masks soft tissue lesions!)
- sometimes you may want to do thoracocentesis, drain the fluid and repeat radiographs
- May help determine etiology (cardiomegaly, mediastinal mass, lymphadenopathy)
- Confirm pleural effusion (masks soft tissue lesions!)
- Thoracic ultrasound
- Pleural fluid acoustic window
- Pleural thickening, masses, abscess
- Thoracic CT
- Neoplasia, abscesses, foreign body
Pleural fluid and neoplasia
Neoplasia is a frequent cause of pleural effusion!*
- Tumors affecting any one of the following locations
- Visceral/parietal pleura, lungs, mediastinum, LN/lymphatics
- Varied fluid types: modified transudate (or exudate), chylous
Pleural fluid and neoplasia: Dx
Dx: identify cells on fluid cytology
- Most common w/ round cell neoplasia (lymphoma - they usually flake off the best)
- Absence of a dx on fluid cytology
- Imaging (ultrasound - thorax AND abdomen, CT)
NOTE: abdomen is easier to biopsy/aspirate than is the thorax
- +/- surgery for exploration and biopsy
- thoracoscopy
- thoracotomy
Hemothorax
- Hemorrhage into the pleural space
- Causes
- Trauma
- Neoplasia
- COAULOPATHY (rodenticide!!!)*
- Vessel rupture
- lung lobe torsion, heartworms, Spirocerca lupi (all not super common)
Hemothorax: dx
- Effusion PCV roughly equals peripheral PCV
- Effusion should NOT clot (platelets and clotting factors get taken back up by pleural surfaces quite quickly!)
- Effusion contains:
- Macrophages
- NO platelets
Hemothorax: tx
- Only tap if necessary to alleviate dyspnea
- Body will absorb RBC’s
- May make worse if coagulopathy present
- Assess coagulation status
- PT and PTT
- Treatment depends on underlying cause
- Vit K and blood products for rodenticide toxicity
- Surgery may be indicated if bleeding mass
