Peripheral nerve blocks are essential for targeted perioperative analgesia, reducing opioids and enhancing recovery. This guide covers sonoanatomy, local anesthetic pharmacology, common upper/lower extremity blocks, complications like LAST, and evidence-based techniques. Ideal for trainees mastering ultrasound-guided regional anesthesia from basics to advanced clinical practice.
Levosimendan is a calcium sensitizer and KATP channel opener that increases contractility without raising intracellular calcium or myocardial oxygen demand. Its active metabolite lasts ~80 hours. Ideal for low cardiac output with renal failure (no dose adjustment) or when milrinone fails. Key risks: hypotension and prolonged effects.
Milrinone is a PDE-3 inhibitor used in cardiac anesthesia as an inodilator—it increases contractility while reducing afterload and pulmonary vascular resistance. Ideal for right ventricular failure and β-blocked patients. Key risks: hypotension and prolonged half-life in renal failure. Avoid bolus if hypotensive or hypovolemic.
Mephentermine is an indirect sympathomimetic that releases endogenous norepinephrine, increasing both heart rate (β-1) and SVR (α-1). Ideal for spinal-induced hypotension with bradycardia or low cardiac output. Longer-acting than ephedrine but risks tachyphylaxis. Avoid in tachycardic or ischemic patients.
A pure alpha-1 agonist causing veno-arterial constriction. First-line for neuraxial-induced hypotension (especially obstetrics). Rapid onset (30–60 sec), short duration. Key risk: reflex bradycardia and reduced cardiac output, particularly if hypovolemic. Use boluses (40–100 mcg) or infusion (0.5–1 mcg/kg/min). Avoid as monotherapy in cardiogenic shock.
Vasopressin is a vasopressor acting on V1a receptors, making it ideal for vasodilatory shock (sepsis, post-bypass vasoplegia). Unlike catecholamines, it works in severe acidosis without causing tachycardia. Dose: 0.01–0.04 U/min infusion. In cardiac arrest, a single 40 U dose may be used as an alternative to epinephrine.
Succinylcholine is the fastest neuromuscular blocker (30–60s onset, 5–10min duration), ideal for RSI. Its dangers include life-threatening hyperkalemia in denervation/burns, malignant hyperthermia, bradycardia in children, and prolonged paralysis in pseudocholinesterase deficiency. Always scrutinize potassium and MH history before use.
Tactile evaluation of the train-of-four is unreliable—fade is undetectable until the ratio falls below 0.4. Quantitative monitors provide a numeric TOF ratio, enabling objective assessment. Residual paralysis (TOF < 0.9) occurs in 30–40% of PACU patients when relying on qualitative PNS alone. Upgrade your practice. Protect your patients.
Halothane sensitizes the heart to catecholamines, causing arrhythmias even with small epinephrine doses. It triggers malignant hyperthermia and immune-mediated hepatitis after repeat exposure. Though obsolete in high-income countries, its unique pharmacology remains heavily tested and relevant for global anesthesia practice.
Pancuronium is a long-acting, non-depolarizing neuromuscular blocker with significant vagolytic activity, causing dose-dependent tachycardia. Its duration (60–100 minutes) and renal/hepatic elimination limit use today. Unlike vecuronium, it cannot be reversed with sugammadex. Best avoided in coronary artery disease or when hemodynamic stability is desired.
