Comprehensive Anesthesia: History, Pharmacology, and Physiological Foundations

What is the primary goal of modern anesthesia?

To block consciousness, interrupt sensory integration, attenuate stress responses, and preserve physiological stability during surgery.

What does anesthesia involve?

Maintaining equilibrium in physiology, optimizing organ function, safeguarding awareness, and ensuring a smooth recovery.

What ancient civilizations experimented with methods to control suffering?

Egypt, Greece, India, and China.

What substances were used in ancient anesthesia practices?

Opium extracts, alcohol, mandrake root, cannabis, and cold temperatures.

Who is known for using a herbal mixture called malfeasant for operations in ancient China?

Hua Tuo.

What marked the official beginning of modern anesthesia?

William T. G. Morton using ether vapor during a neck surgery in 1846.

What anesthetic agent did James Young Simpson introduce for childbirth?

Chloroform.

What is nitrous oxide commonly known as?

Laughing gas.

What is the significance of the Clower ether inhaler and Boyle's machine?

They allowed doctors to control gas flow and oxygen delivery.

Who is recognized as the first scientific anesthetist?

John Snow.

What are the classifications of anesthetic agents based on their route of administration?

Inhalation (volatile), IV anesthetics, local & regional anesthetics, adjunctive drugs, and neuromuscular blockers.

What are some examples of inhalation anesthetics?

Sevoflurane, desflurane, isoflurane, halothane, and nitrous oxide.

What is the primary mechanism of action for local and regional anesthetics?

They block voltage-gated sodium channels, preventing nerve depolarization.

What is the role of GABA in anesthetic pharmacology?

GABA is a neurotransmitter that slows brain activity, and many anesthetics enhance its effect.

What is the effect of NMDA receptor inhibitors in anesthesia?

They block excitatory signals, slowing brain activity and resulting in dissociative anesthesia.

What is the significance of context-sensitive half-time in anesthesia?

It indicates how long it takes plasma levels of a drug to drop after stopping an infusion.

How do inhaled anesthetics affect the cardiovascular system?

They cause dose-dependent vasodilation and mild myocardial depression.

What is the effect of propofol on the cardiovascular system?

It reduces preload and afterload.

What is the effect of ketamine on heart rate and blood pressure?

It increases heart rate and blood pressure through catecholamine release.

How do volatile anesthetics affect the respiratory system?

They decrease tidal volume and increase respiratory rate but blunt the oxygen drive.

What are some examples of adjunctive drugs used in anesthesia?

Opioids (like fentanyl), benzodiazepines (like midazolam), and neuromuscular blockers (like succinylcholine).

What is the primary method of elimination for volatile anesthetics?

They are primarily eliminated through the lungs on exhalation.

What is the role of pharmacokinetics in anesthesia?

It involves the uptake, distribution, and elimination of anesthetic agents.

What is the impact of blood solubility on inhalation anesthetics?

Lower blood solubility leads to faster uptake and quicker action in the brain.

What is the effect of cardiac output on anesthetic gas distribution?

Higher cardiac output can carry gas away from the lungs faster, affecting the speed of anesthetic action.

What is the significance of the term 'context-sensitive half-time'?

It refers to the duration of effect of a drug based on how long it takes for plasma levels to drop after stopping an infusion.

What is the effect of inhaled anesthetics on the cardiovascular system?

They cause dose-dependent vasodilation and mild myocardial depression.

How does propofol affect the cardiovascular system?

Propofol reduces preload and afterload, leading to decreased stroke volume and blood pressure.

What is the impact of volatile anesthetics on respiratory function?

They decrease tidal volume and increase respiratory rate but blunt the oxygen drive.

How do IV anesthetics like propofol and barbiturates affect respiration?

They cause dose-dependent respiratory depression.

What is the unique respiratory effect of ketamine?

Ketamine preserves spontaneous ventilation and airway reflexes.

What is the Meyer-Overton correlation?

It suggests that anesthetics dissolve in neuronal membranes, altering their fluidity.

What does the Protein Receptor Hypothesis propose?

It suggests that anesthetics bind directly to specific protein sites in the brain.

What is the concept of Neural Network Disruption in anesthesia?

It refers to the interruption of information integration required for conscious experience.

What is the effect of general anesthetics on myocardial contractility?

Most general anesthetics depress myocardial contractility by reducing intracellular calcium availability.

How does ketamine affect myocardial oxygen supply and demand?

Ketamine acts as a sympathomimetic, increasing heart rate and blood pressure.

What is the role of nitric oxide in vascular tone regulation?

Nitric oxide relaxes blood vessels, lowering blood pressure.

What happens to cerebral blood flow under anesthesia?

Most anesthetics reduce cerebral blood flow, but some inhaled anesthetics can increase it.

How do volatile anesthetics affect cerebral autoregulation?

Volatile agents weaken cerebral autoregulation.

What is the function of positive end-expiratory pressure (PEEP) during anesthesia?

PEEP helps maintain alveolar recruitment and prevent desaturation.

What is the impact of excessive PEEP?

Excessive PEEP can reduce venous return and cardiac output.

What is the significance of Bispectral Index (BIS) monitoring?

BIS monitoring estimates how 'asleep' the patient is to prevent awareness or over-sedation.

How do volatile anesthetics cause immobility?

They block signal transmission in the spinal cord, stopping movement in response to pain.

What is the difference between immobility and unconsciousness?

Immobility is controlled by the spinal cord, while unconsciousness involves the brain.

What is the effect of opioids like fentanyl on sympathetic responses?

Opioids blunt sympathetic responses while preserving myocardial oxygen balance.

What is the effect of inhaled anesthetics on blood vessels?

Inhaled anesthetics cause blood vessels to release more nitric oxide, leading to relaxation.

What is the risk associated with anesthetic-induced muscle relaxation?

It increases the risk of airway obstruction, especially in supine patients.

How does the brain's oxygen demand relate to anesthetic use?

Most anesthetics reduce the brain's oxygen demand, which also decreases blood flow.

What happens to functional residual capacity (FRC) after induction?

FRC decreases, promoting alveolar collapse and impaired oxygen exchange.

What is the role of catecholamines in the action of ketamine?

Ketamine releases catecholamines, increasing heart rate and blood pressure.

How does anesthesia affect the sensitivity of medullary chemoreceptors?

Anesthesia decreases the sensitivity of chemoreceptors to CO2, blunting ventilatory response.