Anesthesia
The mind is a collection of mental states, thoughts, feeling, emotions and perceptual experience. Neural processes in the brain somehow generate the qualities of the mind and consciousness is an aspect of the mind that involves awareness of these mental states. Perturbation of the brain's active chemistry brings about functional changes in the brain's circuitry which changes in behavior. Anesthetically induced changes in the brain's circuitry likely reflect the strengthening and weakening of synapses through mechanisms such as changes in the number of activated and available receptors, changes in the amount of neurotransmitter released, and changes in intracellular biochemical pathways that are activated by membrane receptors. Anesthetics bring about homeostatic changes in brain physiology that allow surgery to occur.
The objective of anesthesia for functional surgery are to produce the effects of unconsciousness, sedation (amnesia), analgesia (pain relief) and immobility through muscle relaxation (paralysis, partial paralysis or no paralysis). Anesthetics are the vehicle that produce a state in which a surgery can be tolerated. It is commonly accepted that general anesthetics cause immobility by depressing spinal neurons and amnesia and hypnosis by acting on neurons in the brain; there are a long list of molecular targets. GABA type A receptors are involved in the actions of the intravenous anesthetics etomidate and propofol.
An anesthesiologists focus is primarily on patient safety. They accomplish the line of amnesia and awareness through medical management and monitoring of physiologic homeostasis; pulse oximetry, blood pressure. Their goal is to keep the patient unaware, immobile, asleep and plan for them to wake up. They are trying to achieve a balanced blood pressure that reduces blood loss but also allows perfusion to the brain and peripheral structures to avoid blindness or brachial plexus palsy.
The theory of anesthesia is brainstem depression, a blockade of sensory inputs at the thalamus and subsequent cortical information processing; synaptic inhibition. Thalamic blockade keeps the patient asleep, spinal cord blockage keeps the patient from moving by acting at the neuromuscular junction. The physiological effects of anesthesia such as blood pressure.
Stages of Anesthesia
Stage 1 - Induction; the initiation phase of anesthesia where the patient is being put to sleep, typically beginning with inhalation of oxygen and subsequent introduction of intravenous or inhalation anesthetics. The patient may experience dizziness or a state of spastic unrest combined with a heightened sense of hearing and intensified responses to noise, a sense of unreality and a lessening sensitivity to touch and pain proprioception. Intravenous anesthetics usually cause unconsciousness in less than 1 minute. Inhalation agents can also act quickly but they must be inhaled for a short time before they cause unconsciousness.
Stage 2 - Excitement; the patient's physiology shows the effects of anesthetic stimulation where potential responses of muscular fasciculation (sometimes violent), delirium and perturbation of vital signs all could be observed.
Stage 3 - Surgical Anesthesia; the patient's skeletal muscles relax, their breathing becomes regular and eye movements slow and come to a stop, surgery can begin.
This stage is divided into 4 planes:
Plane 1 - The patient still has blink and swallowing reflexes and has regular respiration with good chest motion, they are considered "light"
Plane 2 - The patient's blink reflexes subside and the pupils become fixed, respiration is regular
Plane 3 - The patient's breathing becomes shallow and assisted ventilation is introduced, they are considered "deep"
Plane 4 - Respiratory effort may cease and is required to be controlled by the anesthesiologist.
Stage 4 - Medullary Paralysis; the respiratory centers in the medulla oblongata of the brainstem that control breathing and other vital functions cease., death can result if the patient cannot be revived quickly. This stage should never be reached and careful control of the amounts of anesthetics administered prevent it.
Stage 5 - Anesthesia Maintenance; anesthesia personnell maintain an anesthetic equilibrium while monitoring a patients respiration, heart rate, blood pressure, and other vital functions during surgery. On board anesthetics are adjusted based on patient responses and feedback during the procedure.
Stage 8 - Emergence; the procedure is completed, wound is closed and the anesthetic is stopped. The patients body clears the surgical anesthetic medicines from their system, and autonomic body functions begin to return. The speed of emergence depends on the titrated anesthetics during surgery.
The objective of anesthesia for functional surgery are to produce the effects of unconsciousness, sedation (amnesia), analgesia (pain relief) and immobility through muscle relaxation (paralysis, partial paralysis or no paralysis). Anesthetics are the vehicle that produce a state in which a surgery can be tolerated. It is commonly accepted that general anesthetics cause immobility by depressing spinal neurons and amnesia and hypnosis by acting on neurons in the brain; there are a long list of molecular targets. GABA type A receptors are involved in the actions of the intravenous anesthetics etomidate and propofol.
An anesthesiologists focus is primarily on patient safety. They accomplish the line of amnesia and awareness through medical management and monitoring of physiologic homeostasis; pulse oximetry, blood pressure. Their goal is to keep the patient unaware, immobile, asleep and plan for them to wake up. They are trying to achieve a balanced blood pressure that reduces blood loss but also allows perfusion to the brain and peripheral structures to avoid blindness or brachial plexus palsy.
The theory of anesthesia is brainstem depression, a blockade of sensory inputs at the thalamus and subsequent cortical information processing; synaptic inhibition. Thalamic blockade keeps the patient asleep, spinal cord blockage keeps the patient from moving by acting at the neuromuscular junction. The physiological effects of anesthesia such as blood pressure.
Stages of Anesthesia
Stage 1 - Induction; the initiation phase of anesthesia where the patient is being put to sleep, typically beginning with inhalation of oxygen and subsequent introduction of intravenous or inhalation anesthetics. The patient may experience dizziness or a state of spastic unrest combined with a heightened sense of hearing and intensified responses to noise, a sense of unreality and a lessening sensitivity to touch and pain proprioception. Intravenous anesthetics usually cause unconsciousness in less than 1 minute. Inhalation agents can also act quickly but they must be inhaled for a short time before they cause unconsciousness.
Stage 2 - Excitement; the patient's physiology shows the effects of anesthetic stimulation where potential responses of muscular fasciculation (sometimes violent), delirium and perturbation of vital signs all could be observed.
Stage 3 - Surgical Anesthesia; the patient's skeletal muscles relax, their breathing becomes regular and eye movements slow and come to a stop, surgery can begin.
This stage is divided into 4 planes:
Plane 1 - The patient still has blink and swallowing reflexes and has regular respiration with good chest motion, they are considered "light"
Plane 2 - The patient's blink reflexes subside and the pupils become fixed, respiration is regular
Plane 3 - The patient's breathing becomes shallow and assisted ventilation is introduced, they are considered "deep"
Plane 4 - Respiratory effort may cease and is required to be controlled by the anesthesiologist.
Stage 4 - Medullary Paralysis; the respiratory centers in the medulla oblongata of the brainstem that control breathing and other vital functions cease., death can result if the patient cannot be revived quickly. This stage should never be reached and careful control of the amounts of anesthetics administered prevent it.
Stage 5 - Anesthesia Maintenance; anesthesia personnell maintain an anesthetic equilibrium while monitoring a patients respiration, heart rate, blood pressure, and other vital functions during surgery. On board anesthetics are adjusted based on patient responses and feedback during the procedure.
Stage 8 - Emergence; the procedure is completed, wound is closed and the anesthetic is stopped. The patients body clears the surgical anesthetic medicines from their system, and autonomic body functions begin to return. The speed of emergence depends on the titrated anesthetics during surgery.