Initial phase (2 months):
- Isoniazid (INH)
Can cause hepatotoxicity and peripheral neuropathy (give with Vitamin B6, especially in patients at risk for neuropathy - diabetics, alcoholics, HIV, pregnant)
- Rifampin (RIF)
Excreted as a red-orange compound in urine, tears, sweat, and stool
Can cause hepatotoxicity (less common than with INH)
Induces hepatic microsomal enzymes and may increase hepatic clearance of other drugs
- Pyrazinamide
Commonly causes GI upset
Can cause hepatotoxicity and hyperuricemia (can induce gout flares in patient's at risk)
- Ethambutol
Can cause hepatotoxicity and optic neuritis (screen monthly for visual disturbances)
Continuation phase (4 or 7 months):
- INH
- RIF
Follow-up:
- Repeat sputum smear and culture two months after initiation of therapy
- Liver panel
Wednesday, February 3, 2010
Tuesday, February 2, 2010
Pulsus Paradoxus
Definition: Exaggerated drop in systemic blood pressure during inspiration that can cause weakening of peripheral pulses
Causes:
1) Cardiac: tamponade, shock, pericardial effusion
2) Pulmonary: PE, tension pneumothorax, asthma, COPD
3) Misc: anaphylactic shock, SVC obstruction
Measurement:
1) Inflate a sphygmomanometer cuff as if measuring BP. As the cuff is deflating, measure the systolic pressure at which Korotkoff sounds become audible during expiration and inspiration. The difference between these 2 pressures is the pulsus paradoxus.
2) Decrease in the pulse wave amplitude during inspiration seen on an arterial tracing or pulse oximeter waveform
3) Severe pulsus paradoxus can be palpated in the radial, brachial, or femoral pulses as a weakening or disappearance of the pulse during inspiration
Causes:
1) Cardiac: tamponade, shock, pericardial effusion
2) Pulmonary: PE, tension pneumothorax, asthma, COPD
3) Misc: anaphylactic shock, SVC obstruction
Measurement:
1) Inflate a sphygmomanometer cuff as if measuring BP. As the cuff is deflating, measure the systolic pressure at which Korotkoff sounds become audible during expiration and inspiration. The difference between these 2 pressures is the pulsus paradoxus.
2) Decrease in the pulse wave amplitude during inspiration seen on an arterial tracing or pulse oximeter waveform
3) Severe pulsus paradoxus can be palpated in the radial, brachial, or femoral pulses as a weakening or disappearance of the pulse during inspiration
HIDA scan
HIDA (hepatobiliary iminodiacetic acid) nuclear medicine scan
- IV iminodiacetic acid derivative is taken up by hepatocytes and excreted into bile with concentration in the gallbladder. A series of images are taken visualizing the pathway of bile excretion.
- Used to diagnose obstruction (secondary to cholecystitis or cystic duct obstruction), gall bladder perforation, or congenital abnormalities in the bile ducts
- Normal study: gallbladder visualization within an hour
Abnormal: failure to visualize the gallbladder within 4 hours or leakage into the pericholecystic space
- False positives: severe liver disease causing abnormal HIDA uptake, TPN patients with an already distended gallbladder, biliary sphincterotomy causing decreased filling of the gallbladder
- IV iminodiacetic acid derivative is taken up by hepatocytes and excreted into bile with concentration in the gallbladder. A series of images are taken visualizing the pathway of bile excretion.
- Used to diagnose obstruction (secondary to cholecystitis or cystic duct obstruction), gall bladder perforation, or congenital abnormalities in the bile ducts
- Normal study: gallbladder visualization within an hour
Abnormal: failure to visualize the gallbladder within 4 hours or leakage into the pericholecystic space
- False positives: severe liver disease causing abnormal HIDA uptake, TPN patients with an already distended gallbladder, biliary sphincterotomy causing decreased filling of the gallbladder
Skeletal Survey vs Bone Scan
Skeletal Survey:
- X-rays of the major bones of the body, including chest, spine, skull, pelvis, femora, and humeri
- Used to diagnose fractures, bone metastasis, osteomyelitis, assessment after a trauma, degenerative conditions of the bone, child abuse
Bone Scan - nuclear medicine scan:
- Uses a radionuclide tracer (technetium 99m MDP) that accumulates in areas of bone turnover and increased osteoblast activity
- Used to diagnose fractures hard to diagnose on xrays, bone metastases, osteomyelitis, metabolic disorders of the bone (ie: Paget disease of the bone, hyperPTH, renal osteodystrophy), primary bone tumors
Dual energy X-ray absorptiometry (DXA or DEXA scan):
- Measure bone mineral density
- Used to diagnose and follow osteoporosis
- X-rays of the major bones of the body, including chest, spine, skull, pelvis, femora, and humeri
- Used to diagnose fractures, bone metastasis, osteomyelitis, assessment after a trauma, degenerative conditions of the bone, child abuse
Bone Scan - nuclear medicine scan:
- Uses a radionuclide tracer (technetium 99m MDP) that accumulates in areas of bone turnover and increased osteoblast activity
- Used to diagnose fractures hard to diagnose on xrays, bone metastases, osteomyelitis, metabolic disorders of the bone (ie: Paget disease of the bone, hyperPTH, renal osteodystrophy), primary bone tumors
Dual energy X-ray absorptiometry (DXA or DEXA scan):
- Measure bone mineral density
- Used to diagnose and follow osteoporosis
Peaks + Troughs
Peak and trough levels are methods used to establish the effectiveness of a drug.
Peak:
- Highest drug level after distribution
- Drawn after the last dose of drug, usually one hour.
- Commonly obtained with use of aminoglycosides
- Used to change dose
Trough:
- Lowest drug level that is needed to reach therapeutic range
- Drawn before the next dose of drug is given.
- Commonly obtained with use of vancomycin
- Used to change frequency
Peak:
- Highest drug level after distribution
- Drawn after the last dose of drug, usually one hour.
- Commonly obtained with use of aminoglycosides
- Used to change dose
Trough:
- Lowest drug level that is needed to reach therapeutic range
- Drawn before the next dose of drug is given.
- Commonly obtained with use of vancomycin
- Used to change frequency
IRIS
IRIS - Immune reconstitution inflammatory syndrome
Definition:
Worsening of preexisting infectious processes (ie: herpes zoster, TB, MAC, CMV, Cryptococcus) after initiation of HAART treatment secondary to re-activation of the immune system
Management:
- Treat underlying opportunistic infection
- Continue ART treatment unless patient is experiencing life-threatening IRIS requiring hospitalization, intubation, etc
- Consider prednisone (1 mg/kg/day with a 10-14 day taper) to decrease inflammatory response
Definition:
Worsening of preexisting infectious processes (ie: herpes zoster, TB, MAC, CMV, Cryptococcus) after initiation of HAART treatment secondary to re-activation of the immune system
Management:
- Treat underlying opportunistic infection
- Continue ART treatment unless patient is experiencing life-threatening IRIS requiring hospitalization, intubation, etc
- Consider prednisone (1 mg/kg/day with a 10-14 day taper) to decrease inflammatory response
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