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10 Cards in this Set
- Front
- Back
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Intraop Hypotension definition |
There is no uniform definition for IOH
Frequently used definitions include SAP below 80 mmHg, a decrease in SAP of more than 20% below baseline, and a combination of definitions consisting of an absolute SAP below 100 mmHg and/or 30% decrease below baseline. MAP values below 65 mmHg and MAP values 20% below preoperative baseline. |
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Causes |
Preload
True hypovolemia
-ongoing hemorrhage -inadequate fluid replacement -preexisting hypertension -fluid sequestration - vomiting/diarrhea -osmotic/diuretic polyuria
Relative hypovolemia
- PPV -Tension pneumothorax/tamponade - Caval compression - PE/pulmonary hypertension - head up position - valvular disease
After load
- Neuraxial -Anaphylaxis/transfusion reaction - systemic inflammation/sepsis -Liver failure - Hypothyroidism - Drugs... Antihypertensives, antiarrhythmics, anticonvulsants, anesthetic agents
Contractility
- MI -Dysrrhythmia - CHF - Hypothermia - Hypothyroidism - MH - Hypocalcemia - Severe acidosis - Drugs...Ca channel and beta blockers blockers, anti arrythmics, anesthetic agents (benzo, barbiturates) , LAST
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Risk factors |
older age high ASA class male sex lower pre-induction SAP general anaesthesia with propofol the combination of general and regional anaesthesia the duration of surgery emergency surgery antihypertensive medications |
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Intraop hypotension Postop outcomes |
-myocardial injury -acute kidney injury -death The risk for acute kidney and myocardial injury markedly increased below lowest intraoperative MAP values of 55–60 mmHg. Even short durations (i.e., 1–5 minutes) of an intraoperative MAP less than 55 mmHg were associated with acute kidney and myocardial injury. |
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Treatment |
On going debate in which Tmt modality actually improves outcomes, larger studies needed. -Vasoactive agents -Fluid -Blood products Pneumatic leg compressions have been shown to improve intraop Hypotension in minor surgeries, but whether they can be replicated to major surgeries is still unknown |
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Which PTS needs higher MAP |
Chronic hypertension Raised ICP Beach chair position Carotid endarterectomy |
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Intraop HTN causes |
Pre existing causes - pre existing undiagnosed or poorly controlled HTN
Increased sympathetic tone -Inadequate anesthesia and analgesia -Hypoxemia -Airway manipulation during laryngoscopy, extubation -Hypercapnia
Drug overdose - Adrenaline, Ketamin, ergometrine
Others - MH, pheochromocytoma, Thyroid crisis, raised ICP , hypervolemia, aortic cross clamping |
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Troubleshooting of causes |
Intubation - Lidocaine can blunt airways Inadequate anesthesia - Beware of empty vaporizers - sweating , tears, tachycardia, movement, grimace Hypercapnia - watch out for inadequate TV, depleted absorbent, disconnection in breathimg circuit, inadequate frash gas flow Hypoxia - increases cardiac output - late sign of hypoxia |
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BP lowering agents |
Nitroprusside- 0.5-10mcg/kg/min, 30-60sec onset, lasts 1-5mins Nitroglycerine- 0.5-10mcg/kg/min, 1min onset, lasts 3-5 mins Beta blockers -esmolol- 0.5mg/kg in 1 min, 50-300mcg/kg/min infusion, onset 1 min, 12-20min duration -labetolol- 5-20mg, 1-2 mins onset, 4-8 hrs duration -propanalol- 1-3 mg, 1-2 mins onset, 4-6hrs duration Hydralazine- 5-20mg, 5-20mins onset, 4-6 hrs duration Nifidipine sL- 10mg, 5-10mins onset, 4hrs duration Methyldopa- 250-1000mg, 2-3 hrs onset, 6-12 hrs duration Nicardipine- 0.25-0.5mg, 1-5mins onset, 3-4hrs duration |
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Specific scenarios |
Urgent reduction - NTG, Nitroprusside or esmolol infusion HTN + Ischemia+ poor LV function - NTG infusion HTN + ischemia + tachycardia - esmolol, labetolol HTN + HF - enalapril HTN+ pheochromocytoma - labetolol, phentolamine |
