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Diagnostic Methods: Respiratory Tests

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5 kinds of Respiratory tests
Thoracentesis: Pleural effusion/tranfusion; Interstitial Lung Dz (ILD), Cancer, Absestosis/pneumocosis
Sputum: PNA and TB ( & mycoses)
Pharyngeal: Bordetella, RSV
Throat & Nasal: Strep, Flu and Mono
Sputum test categories, follow-up tests
TB, CA, PNA
CA: Abnormal cells, Marker ABs/enz.s
PNA: Gram stain: G+: Pneumococcus;
G-: MPP, Klebsiella, HiB, Legionnaire's, Serratia
TB: Acid-fast stain
Sputum collection
Deep cough or suction
Throat culture use & technique
Collect at tonsilar pillars. New swab for each pathogen
Lab: 2-3 days, Strep, Mono, 'Flu
Rapid Test: same day, only 70% sensitive
Nasopharyngeal culture use & technique
Insert swab thru nostril to pharynx.
BEST test for Bordatella in first 2 weeks
RSV in infants can be fatal. Check early!
Bedside thoracentesis/bronchoalveolar lavage use & technique
Bronchoalveolar lavage w/ 150 mL saline. Collect w/ bronchoscope and do Gram, cytology (CA), & fluid analysis
Exudate vs Transudate: When & How
IF pleural effusion suspected or seen on CXR:
EXUDATE--> Cancer, PNA, Trauma, Asbestos, (PE). Exudate will be milky or bloody. LDH ELEVATED at >0.6 X serum and PROTEINS elevated at >0.5 X serum
TRANSUDATE --> CHF, Cirrhosis, Nephrosis, Hypoalbuminemia, Constrictive pericarditis, PE. Transudate may be clear (ascites/edema/CHF) or cloudy, from neutrophils and cellular debris. LDH is NOT ELEVATED
PPD
Purified Protein Derivative used in Mantoux test for TB
Detects EXPOSURE, not Ix. Read induration @ 48-72 hr. If positive, order CX & begin tx w/ isoniazid &/or rifampin
Two-step PPD
Double negative needed on Mantoux.
2nd test 1-2 weeks after 1st, given in same area. Positives are usually "boosted" responses from previous Infection.
Mantoux (PPD) 5mm positive criteria
HIV+
Direct exposure to TB pt
IV user w/ UNKNOWN HIV status
Mantoux (PPD) 15 mm criteria
No risk factors
Mantoux (PPD) 10 mm criteria
HIV-neg IV user, foreigner, low socio-economic, extended care, kids <4yrs, immuno-compromised, healthcare givers
Familial COPD S/s, test & use/limitation
S/s: FamHx, cyanosis, dyspnea unaffected by albuterol, finger clubbing.
Test: Alpha-1 Antitrypsin (AAT). Protease inhibitor that protects lower airways. Collect in Red cap tube (serum)
Deficiency is familial, increases risk for COPD in 20s-30s.
Acute phase product, like ESR & CRP: may elevate during infections
Alpha 1 Antitrypsin-associated diseases
COPD is main disease. Others: Cirrhosis and Panniculitis- nodular inflammation of subcutaneous tissues.
Cystic Fibrosis (CF) test
Pilocarpine iontophoresis test- known as Sweat Chloride test"
GOLD STANDARD test; 2 tests on 2 days
Cl- ions are tested:
Normal: <40
Borderline: 40-60
Positive CF: >60. 30% Caucasians are carriers
PFT/Spirometry definition. What 3 classes of conditions does it identify?
Pulmonary Function Test. Distinguishes chronic RESTRICTIVE, chronic OBSTRUCTIVE, and PERFUSION conditions
Obstructive lung diseases
1)COPD = emphysema & chronic bronchitis;
2) Asthma
Distinguishing COPD from Asthma
1) Asthma responds to albuterol, COPD doesn't
2) Asthma is episodic, COPD is chronic.
Restrictive lung diseases
1) Chronic Interstitial Lung Disease = Sarcoidosis & Pulmonary Fibrosis;
2) Adult Respiratory Distress Syndrome [ARDS];
3) Muscular Dystrophy [MD] and Amyotrophic Lateral Sclerosis [ALS],
4) Obesity;
Pulmonary perfusion disorders
1) Pulmonary Embolism
2) Pulmonary vasculitis
3) R->L shunts [e.g., Tetralogy of Fallot]
Spirometry predictive factors
Gender, ht, wt, age, race.
Caucasians have 20% greater values
80% predicted values are used for normal
ABG stands for what? Normal values?
Arterial Blood Gas
Normals:
pH: 7.35-7.45
PaCO2: 35-45 mm Hg
PaO2: 80-95 mm Hg
HCO3: 22-26 mEq/L
O2 Sat 95-99%
TB signs & symptoms, when to test
Productive cough, hemoptysis, night sweats, weight loss; also if recent TB contact or new immigrant.
Three classes of Spirometry tests
1) Flow rates;
2) Volumes (Capacities);
3) Gas exchange
Effect of vomiting on ABGs
Towards Metabolic Alkalosis
Effect of Diarrhea on ABGs
Towards Metabolic Acidosis
Vital Capacity
IRV + TV + ERV, where:
IRV = Inspiratory reserve volume,
TV = Tidal volume
ERV = Expiratory reserve volume
TLC
VC + RV, where:
-VC = Vital capacity
-RV = Residual volume
Inspiratory capacity
TV + IRV, where
-TV = tidal volume
-IRV = Inspiratory Reserve Volume
FEF definition and how it's derived
Forced Expiratory Flow is the middle of FEV1: average forced flow rate
Effect of OBSTRUCTIVE diseases on Lung Volumes. What causes this effect?
Increases TLC, RV, & FRC, because air's trapped INSIDE, increasing all the static volumes.
Effect of RESTRICTIVE diseases on Lung Volumes. What causes this effect?
Decreases TLC, RV, FRC, because air cannot be drawn in, so static values are reduced.
FEV1 : FVC in OBSTRUCTIVE dz
FEV1 : FVC compares volume expelled in 1 sec to total expelled. DECREASED w/ obstruction
FEV1 : FVC effect of RESTRICTIVE disease
Even though both values decrease, the FEV1 : FVC ratio is normal to increased
Vital Capacity in OBSTRUCTIVE dz
REDUCED, (Larger initially). Use only a portion of capacity because of obstruction
Vital Capacity in RESTRICTIVE dz
REDUCED. Restricted filling lowers space used.
Volume/Time in OBSTRUCTIVE dz
Smaller volume/sec
Volume/Time in RESTRICTIVE dz
Unimpeded volume/sec, but ratio increased