MindMap Gallery surgical anesthesia
Surgery: During artificial ventilation, the symmetrical rise and fall of the bilateral thorax can be seen, and clear breath sounds can be heard during auscultation of both lungs; the tube wall is clear during inhalation, and obvious "white mist"-like changes can be seen during exhalation; if spontaneous breathing occurs, continue Behind the anesthesia machine, the breathing bag can be seen expanding and contracting with breathing; ETCO2 has a waveform display.
Edited at 2022-09-02 00:07:49El cáncer de pulmón es un tumor maligno que se origina en la mucosa bronquial o las glándulas de los pulmones. Es uno de los tumores malignos con mayor morbilidad y mortalidad y mayor amenaza para la salud y la vida humana.
La diabetes es una enfermedad crónica con hiperglucemia como signo principal. Es causada principalmente por una disminución en la secreción de insulina causada por una disfunción de las células de los islotes pancreáticos, o porque el cuerpo es insensible a la acción de la insulina (es decir, resistencia a la insulina), o ambas cosas. la glucosa en la sangre es ineficaz para ser utilizada y almacenada.
El sistema digestivo es uno de los nueve sistemas principales del cuerpo humano y es el principal responsable de la ingesta, digestión, absorción y excreción de los alimentos. Consta de dos partes principales: el tracto digestivo y las glándulas digestivas.
El cáncer de pulmón es un tumor maligno que se origina en la mucosa bronquial o las glándulas de los pulmones. Es uno de los tumores malignos con mayor morbilidad y mortalidad y mayor amenaza para la salud y la vida humana.
La diabetes es una enfermedad crónica con hiperglucemia como signo principal. Es causada principalmente por una disminución en la secreción de insulina causada por una disfunción de las células de los islotes pancreáticos, o porque el cuerpo es insensible a la acción de la insulina (es decir, resistencia a la insulina), o ambas cosas. la glucosa en la sangre es ineficaz para ser utilizada y almacenada.
El sistema digestivo es uno de los nueve sistemas principales del cuerpo humano y es el principal responsable de la ingesta, digestión, absorción y excreción de los alimentos. Consta de dos partes principales: el tracto digestivo y las glándulas digestivas.
anaesthetization
Preparation before anesthesia and medication before anesthesia
Pre-anesthesia condition assessment
Purpose
Ensure patient safety during anesthesia and reduce complications of anesthesia surgery
content
Comprehensively understand the condition and what examinations or preparations are needed; clarify the deficiencies in organ function, complications that may occur during the operation, and preventive and treatment measures. Surgical methods, positions and possible disruption and damage to physiological functions; estimate the patient's tolerance to anesthesia and surgery; select anesthesia methods, anesthetics and pre-anesthetic medications, and formulate an anesthesia plan
Medical history collection
Atropine should be used with caution in patients with glaucoma, and pethidine should be used with caution in patients taking monoamine oxidase inhibitors.
Physical examination
Adequate airway assessment is a key step to ensure smooth tracheal intubation and respiratory maintenance during anesthesia.
laboratory tests
Routine examinations such as hematuria, liver and kidney function, coagulation function, infection indicators, electrocardiogram and chest X-ray
Physical Status Assessment Class (ASA)
Preparations before anesthesia
mental state preparation
Preoperative visit (medical history review), verbal comfort, sedative medication
physical condition preparation
Improve nutritional status and correct pathophysiological conditions (dehydration, electrolytes, acid-base balance, cardiopulmonary function, diabetes, coagulation mechanism)
Gastrointestinal tract preparation
Avoid gastric reflux, vomiting, aspiration, lung infection, suffocation and other accidents during the perioperative period
Preparation of anesthesia equipment, utensils and drugs
Anesthesia machine, oxygen source, monitor, anesthesia laryngoscope, endotracheal tube, etc. Checking of preoperative treatment medications and intraoperative anesthetic medications
Anesthetic options
Based on the anesthesiologist’s ability, patient condition, surgical method and time, anesthesia monitoring equipment conditions, etc.
informed consent
Pre-anesthetic medication
Purpose
Relieve anxiety and/or produce amnesia; increase pain threshold and enhance analgesia; inhibit respiratory gland activity to prevent aspiration; eliminate adverse neural reflexes
Commonly used drugs
transquillizers
diazepam, midazolam
hypnotics
Phenobarbital
Narcotics
Morphine, pethidine
Anticholinergics
Atropine, scopolamine
drug selection
The type, dosage, administration route and time of medication are selected according to the anesthesia method and the patient's condition.
General anesthesia mainly uses sedatives and anticholinergics. If there is severe pain, analgesics will be added. Spinal anesthesia will mainly use sedatives. If the puncture is difficult or tense, analgesics will be added. Atropine will be added for those with possible bradycardia. If the general condition is poor, The dose may be reduced for the elderly, those with cachexia, and hypothyroidism; the dose may be increased for those with young age, hyperthyroidism, and sedatives for coronary heart disease and hypertension; generally intramuscular injection 30-60 minutes before anesthesia;
Classification of anesthesia
general anesthesia
Inhalation anesthesia; intravenous anesthesia; basal anesthesia: rectal injection, intramuscular injection
Local anesthesia
Topical anesthesia; local infiltration anesthesia; regional block; nerve block
neuraxial block
subarachnoid block; epidural block; caudal block
compound anesthesia
general anesthesia
Overview
concept
Anesthetics enter the human body through breathing or intravenous or intramuscular injection, causing suppression of the central nervous system. Clinical manifestations include loss of consciousness, amnesia, loss of pain throughout the body, a certain degree of muscle relaxation and reflex suppression. This anesthesia method is called general anesthesia.
Features
The depth of anesthesia is related to blood drug concentration, can be adjusted, and is completely reversible
Classification (by route of administration)
Inhalational Anesthesia Intravenous Anesthesia
general anesthetic
inhalation anesthetic
Physicochemical properties and pharmacological properties
The oil/gaspartition coefficient, that is, the fat solubility of the anesthetic, is directly proportional to the strength of the anesthetic.
The blood/gas partition coefficient is the water solubility of the anesthetic. The smaller it is, the better the controllability of the anesthetic.
Minimum alveolar concentration (MAC) is the lowest alveolar concentration that can prevent 50% of patients from shaking their heads or moving their limbs during skin incision when a certain inhaled anesthetic is inhaled with pure oxygen at one atmospheric pressure. . The smaller the MAC, the stronger the anesthetic effect
Factors affecting alveolar drug concentration (FA)
FA and FA/FI (rate of rise in drug alveolar concentration) depend on the rate of drug delivery and uptake by the pulmonary circulation
Ventilation effect: The greater the ventilation volume, the faster the FA and FA/FI rise.
Concentration effect: the higher the FI, the faster the FA rises
Cardiac output (CO): The greater the CO, the slower the FA rises
Blood/gas distribution coefficient: The higher the blood/gas distribution coefficient, the slower the FA rises.
The difference in drug concentration between alveoli and venous blood (F A-V) is larger, and the FA rises more slowly.
Metabolism and Toxicity:
metabolism
Excreted via the respiratory tract (prototype), excreted via the kidneys (a small amount), metabolized by the liver (CytP450) →kidney
toxicity
Nephrotoxicity is produced by the intermediate metabolite inorganic fluorine (F-). The lower the metabolic rate, the lower the toxicity. [ F-] <50 μmol/L non-toxic; [ F-] 50-100 μmol/L possible toxicity; [ F-] >100 μmol/L toxic
Commonly used inhalation anesthetics
Nitrous oxide (N2O, laughing gas)
Pharmacological characteristics
⒈ The anesthetic effect is extremely weak; ⒉ Mildly inhibits myocardium and has little impact on hemodynamics; ⒊ Mildly inhibits breathing and has no respiratory tract irritation; ⒋ Low liver and kidney toxicity
Clinical application
⒈ Combined application with other anesthetic drugs; ⒉ Severe shock or critically ill patients; ⒊ Labor analgesia
Contraindications
Patients with intestinal obstruction, air stasis, and pneumothorax
Precautions
When continuing to inhale, the oxygen concentration must be >0.3; when stopping inhalation, <br>pure oxygen must be inhaled for 5-10 minutes (diffuse hypoxia)
Sevofluane
It has a fast onset of action and a low incidence of nausea and vomiting. It is suitable for inhalation induction, especially for induction in children and difficult airways. Disadvantages: unstable in the presence of soda lime
Desflurane
It has a weak effect, extremely rapid onset of action, and strong neuromuscular blocking effect. Disadvantages: expensive, requires special vaporizer
intravenous anesthetic
Overview
concept
Drugs that enter the body through intravenous injection and act on the central nervous system through blood circulation to produce general anesthesia are called intravenous anesthetics
advantage
① Fast and stable induction, no airway irritation; ② No environmental pollution, no special equipment required; ③ Does not inhibit HPV (human papilloma virus), suitable for unilateral lung ventilation
Pharmacokinetic characteristics
⒈ After entering the blood, it binds to plasma proteins and has pharmacological activity in the free state; ⒉ It is metabolized by the liver and excreted by the kidneys; ⒊ Some metabolites have pharmacological activity and affect recovery;
Classification
⒈ Barbiturates: thiopental sodium, methylbarbital sodium, etc.; ⒉ Non-barbiturates: ketamine, etomidate, propofol, etc.
Commonly used intravenous anesthetics
Thiopental sodium
Pharmacological characteristics:
⒈ Commonly used concentration is 2.5%, aqueous solution is highly alkaline ph 10-11 ⒉ Rapid onset of action (30 s), short duration of action (15-20 min) ⒊ Reduces cerebral oxygen consumption, cerebral blood flow and intracranial pressure, and has brain protective effect ⒋ Strong cardiovascular inhibitory effect ⒌ Strong respiratory depression, increased throat and bronchial sensitivity ⒍ Repeated use of the drug can cause delayed awakening (transfer from brain tissue to fat, accumulate in fat, and re-enter the blood later)
Ketamine
Pharmacological characteristics
⒈ Quick onset, short action time, strong analgesic effect ⒉ Increase cerebral blood flow, intracranial pressure and brain metabolism ⒊ Exciting sympathetic nerves, but directly inhibiting myocardium ⒋ Mild effect on breathing, large dose inhibition, stimulating saliva secretion ⒌ Isolation Anesthesia (dissociative anesthesia): Ketamine selectively excites the medulla oblongata and limbic system and inhibits the effects of the thalamus. Manifested as feeling separated from the environment; emotional activity inconsistent with disappearance of consciousness; appearance seemingly inconsistent with light anesthesia and deep analgesia
Clinical application
Induction of general anesthesia, 1-2mg/kg iv; combined with other intravenous anesthesia for anesthesia maintenance; basic anesthesia in children and anesthesia for minor surgeries in adults; auxiliary medication for nerve block; bronchial smooth muscle relaxation
Adverse reactions
Transient apnea, hallucinations, nightmares, psychiatric symptoms and increased intraocular pressure
Precautions
① Hypertension ② Increased intracranial pressure ③ Increased intraocular pressure ④ Insufficient myocardial blood supply ⑤ Epilepsy should not be used
etomidate
Pharmacological characteristics
Quick onset, short action time, no analgesic effect; reduces cerebral blood flow, intracranial pressure and metabolic rate; has little impact on the circulatory system, mild coronary dilation; weak respiratory depression; has no significant impact on liver and kidney function
Clinical application
Induction of general anesthesia, especially for critically ill patients with coronary heart disease, poor cardiac function and the elderly and frail
Adverse reactions
Myoclonus, venous irritation, adrenal insufficiency, postoperative nausea and vomiting
midazolam
Pharmacological characteristics
It has strong sedative-hypnotic, anterograde amnesia, anti-anxiety, anti-convulsant and muscle tone-reducing effects; its respiratory depressant effect is related to dose and injection speed.
Clinical application
Pre-anesthetic medication and auxiliary anesthesia medication (1-2 mg intravenously can help you fall asleep); general anesthesia induction (0.15-0.2 mg/kg)
Propofol (propofol, propofol)
Pharmacological characteristics
⒈ Rapid onset of action (30 s), short action time (3-10 min); ⒉ Reduce cerebral blood flow, intracranial pressure and cerebral metabolic rate, and have a brain protective effect; ⒊ Significant circulation inhibition; ⒋ Significant respiratory inhibition
Clinical application
① General anesthesia induction and maintenance ② Other anesthetic auxiliary drugs (1-2 mg/kg.iv) ③ Outpatient minor surgery
Adverse reactions
Pain at the injection site, respiratory and circulatory depression
muscle relaxants
Mechanism
The conduction process of nerve impulses at the neuromuscular junction: impulse → release of acetylcholine from the presynaptic membrane → binding to postsynaptic membrane receptors → depolarization of the postsynaptic membrane → muscle contraction
The mechanism of action of muscle relaxants: interfering with the conduction of nerve impulses at the neuromuscular junction
Depolarizing muscle relaxants
Mechanism
The molecular structure of this type of drug is similar to acetylcholine, but it has a stronger affinity for postsynaptic receptors and is not easily degraded by cholinesterase. Therefore, it causes continuous depolarization of the postsynaptic membrane without repolarization, resulting in muscle relaxation.
Features
⑴ The postsynaptic membrane is continuously depolarized; ⑵ Fasciculation occurs when the drug is used for the first time; ⑶ Cholinesterase inhibitors cannot antagonize its effect; ⑷ Desensitization occurs when the drug is used repeatedly (Phase II block)
Representative medicine
succinylcholine (succinylcholine,scoline)
non-depolarizing muscle relaxants
Mechanism of action
This type of drug can bind to postsynaptic receptors, but lacks pharmacological activity, preventing acetylcholine from binding to receptors and causing muscle relaxation.
Features
① Can bind to acetylcholine receptors but is inactive ② Does not affect the release of acetylcholine in the preprominent membrane, but makes it ineffective ③ No muscle tremor after the first administration ④ Its effect can be antagonized by cholinesterase inhibitors ⑤ Dose-dependent sex
Representative medicine
Tubocurarine, vecuronium bromide, atracuramide, etc.
Precautions when applying muscle relaxants
① Assist or control breathing, and perform tracheal intubation ② Succinylcholine can cause a temporary increase in blood K, intraocular pressure and intracranial pressure; it is contraindicated in patients with severe trauma, burns, paraplegia, glaucoma, and increased intracranial pressure ③ Combined Patients with neuromuscular junction diseases, such as myasthenia gravis, are prohibited from using non-depolarizing muscle relaxants④ Some muscle relaxants have the effect of releasing histamine (tubocurarine, pancuramide), and should be used with caution by those with asthma and allergies ⑤ It has no sedative and analgesic effect and needs to be used under the action of general anesthesia. ⑥ Hypothermia can prolong its action time; inhaled anesthetics, antibiotics (streptomycin, gentamicin, polymyxin) and magnesium sulfate have enhanced effects.
Narcotic analgesics
morphine
It can increase the pain threshold and relieve pain. It can eliminate tension and anxiety, cause euphoria, and is addictive. It has a significant inhibitory effect on the respiratory center. Mainly used for analgesia and treatment of pulmonary edema caused by left heart failure. Often used as pre-anesthetic medication and anesthetic auxiliary drug
Pethidine (pethidine, Dolantin):
It has analgesic, hypnotic, and smooth muscle spasm relief effects. It has an inhibitory effect on myocardial contractility. There is a feeling of euphoria after taking the drug and it is addictive
fentanyl
The analgesic effect is 75-125 times stronger than morphine. Has respiratory depressant effect. Used as an auxiliary drug for anesthesia, or for induction of anesthesia to alleviate cardiovascular reactions during intubation. Anesthesia commonly used for cardiovascular surgery
remifentanil
Ultra-short-acting analgesics can significantly slow down the heart rate, cause dose-dependent respiratory depression, and have a high incidence of myotonia.
Basic structure and application of anesthesia machine
Gas supply: cylinder, central gas supply.
Evaporator
anesthetic breathing circuit
open circuit; semi-closed or semi-open circuit; closed circuit
Respirator (ventilator): fixed volume type, constant pressure type
endotracheal intubation
Purpose
① Keep the patient's respiratory tract open during anesthesia, prevent foreign bodies from entering, and facilitate sputum suction and blood accumulation; ② Facilitate artificial and mechanical ventilation: used for respiratory failure, resuscitation, poisoning, and neonatal asphyxia; ③ Facilitate inhalation of general anesthetics
How to confirm the location of the catheter
During artificial ventilation, the symmetrical rise and fall of the bilateral thorax can be seen, and clear breath sounds can be heard during auscultation of both lungs; the tube wall is clear during inhalation, and obvious "white mist"-like changes can be seen during exhalation; if there is spontaneous breathing, after connecting to the anesthesia machine It can be seen that the respiratory sac expands and contracts with breathing; ETCO2 has a waveform display
Complications of endotracheal intubation
Injuries to the teeth, oral cavity, throat, nasal cavity, etc., joint dislocation; severe choking, larynx and bronchial spasm, cardiovascular reflexes; respiratory tract obstruction caused by the inner diameter being too small or too large, too soft or deformed; accidentally entering one side of the bronchus or prolapse of the tube ; Long-term inflatable compression causes local mucosal and ciliary ischemia, mucosal shedding, cessation of ciliary activity, local ulcers, and cartilage softening and necrosis.
Administration of general anesthesia
induction of anesthesia
The process of taking a patient from an awake state to a state in which consciousness disappears or is insensitive to pain after the administration of anesthetic drugs.
① Inhalation induction method: open drip method, mask inhalation method; ② Intravenous induction method: rapid, comfortable and pollution-free
Anesthesia maintenance
Using drugs to keep the patient under anesthesia
① Inhalation anesthetic maintenance, ② Intravenous anesthetic maintenance, ③ Combined General Anesthesia
After recovering from anesthesia to consciousness, the body's pain sensation and reflexes return to their normal state.
The inhibitory process of general anesthetics on the central nervous system (consciousness, pain perception, reflex activities, muscle relaxation, breathing and circulation)
Complications of general anesthesia and their management
① Regurgitation and Aspiration; ② Airway Obstruction: upper airway obstruction, lower airway obstruction; ③ Hypoventilation; ④ Hypoxia Hypoxemia; ⑤ Hypotension; ⑥ Hypertension; ⑦ Arrhythmia; ⑧ Malignant hyperthermia, convulsions and convulsions; ⑨ Delayed awakening or unconsciousness
Local anesthesia
Pharmacology of local anesthetics (PHARMACOLOGY)
Chemical Structure and Classification
⒈Structure: Contains aromatic ring, amine group and intermediate chain ⒉Classification: Divided into esters and amides according to the intermediate chain
Physicochemical properties and anesthetic properties
⒈Dissociation constant (pKa): ①The larger the pKa, the longer the onset time; ②The larger the pKa, the worse the dispersion performance
⒉ Fat solubility: The higher the fat solubility, the stronger the anesthetic effect.
⒊Protein binding rate: The higher the plasma protein binding rate, the longer the action time
Absorption, distribution, biotransformation and clearance
Factors affecting drug absorption: ① drug dose ② blood supply at the site of action ③ drug performance ④ vasoconstrictor
Distribution: blood → lungs → organs with rich blood supply → organs with poor blood supply
Biotransformation and clearance: Amides are degraded by mitochondrial enzymes in the liver, esters are degraded by pseudocholinesterase, and a small amount of the prototype is excreted by the kidneys.
Adverse reactions of local anesthetics
toxic reactions
reason
① A single dose exceeds the patient's tolerance ② Injection into the blood vessel by mistake ③ The site of action is rich in blood vessels ④ The patient has poor physical constitution, poor tolerance, and hypersensitivity reaction
Influencing factors
PaCO2, temperature, pH, drug interactions
Performance
Mainly manifested in the central nervous and cardiovascular systems
prevention
① The dosage at one time should not exceed the limit; ② Withdraw before injecting, and inject while inserting the needle; ③ Individualized medication, reduce the dosage in areas with rich blood supply; ④ Add epinephrine if there are no contraindications; ⑤ Use diazepam and barbiturates for preoperative medication Drug-like
treat
① Stop the drug and inhale oxygen; ② For mild cases, diazepam 0.1 mg/kg can be given intravenously or intramuscularly; ③ In the event of convulsions or convulsions, propofol 1-2 mg/kg can be given intravenously; ④ Hypotension: ephedrine or metahydroxylamine; Slow heart rate: atropine; ⑤ Respiratory and cardiac arrest: cardiopulmonary resuscitation, and intravenous administration of 20% fat emulsion 1.5mL/kg, and continuous infusion of 0.25mL/kg/min if necessary
allergic reaction
Performance
Urticaria, throat edema, bronchospasm, and decreased BP occur
treat
Intravenous injection of epinephrine 50-100 μg, demimethamine 20-40 mg, and antihistamines such as diphenhydramine 10-25 mg, oxygen inhalation
Local anesthesia method
topical anesthesia
A painless state produced by contacting a local anesthetic with strong penetration into the local mucosa, allowing it to penetrate the mucosa and block superficial nerve endings.
Commonly used topical anesthetics and anesthesia methods
Ocular surface anesthesia: commonly used 0.5-1% tetracaine, 2% lidocaine
Surface anesthesia of the nasal cavity, throat, trachea and bronchi: 1-2% tetracaine or 2-4% lidocaine can be used
Urethral topical anesthesia
local infiltration anesthesia
Local anesthetic is injected in layers along the surgical incision line to block nerve endings in the tissue.
regional anesthesia
Inject local anesthetic around the surgical area and at the bottom to block the nerve trunks and nerve endings entering the surgical area
neuraxial anesthesia
Overview
concept
Anesthesia of the lower body or area produced by injecting local anesthetic into the subarachnoid space or epidural space is called neuraxial anesthesia
Features
⒈The patient is conscious; ⒉The analgesic effect is accurate and the muscle relaxation effect is good; ⒊The visceral stretch reflex cannot be completely eliminated; ⒋It may cause physiological disorders
Anatomical basis of neuraxial anesthesia
spine and spinal canal
Four physiological curvatures: when lying on your back, C3 and L3 are the highest, and T5 and S4 are the lowest.
The adult spinal cord terminates at the lower edge of the L1 vertebral body or the upper edge of L2, and in newborns at the lower edge of L3; the lumbar puncture should be below L2 in adults, and in the gap below L3 in children.
ligament
From outside to inside, they are the supraspinal ligament, interspinous ligament and ligamentum flavum.
Spinal cord, meninges and cavities
lower end of spinal cord
L1 lower edge or L2 upper edge
meninges
dura mater, arachnoid mater, pia mater
lacunar
epidural space, subdural space, subarachnoid space
Root dura mater, root arachnoid membrane and root pia mater
That is, the part of the dura mater, arachnoid mater, and pia mater extending along the spinal nerve to both sides to wrap around the spinal nerve root. It has a villus structure and functions to drain cerebrospinal fluid and remove particulate matter in the subarachnoid space.
sacral canal
The part of the spinal canal located within the sacrum is the part used for sacral canal block.
spinal nerve
There are 31 pairs in total (8 for the neck, 12 for the chest, 5 for the waist, 5 for the sacral, and 1 for the tail), which are formed by the merger of the front and rear roots. The anterior root is composed of motor and sympathetic afferent fibers, and the posterior root is composed of sensory and sympathetic afferent fibers.
The mechanism and physiology of spinal anesthesia
cerebrospinal fluid
The total volume for adults is 120-150ml, and the subomental space is 25-30ml; physical properties: transparent, pH7.35, specific gravity 1.003-1.009
drug action site
The main site of action is the spinal nerve roots, followed by the surface of the spinal cord. Drug diffusion route: Subarachnoid space block acts directly on the spinal cord; epidural block may be: ① Entering the subarachnoid space at the root through the arachnoid villi ② The drug liquid leaks out of the intervertebral foramen and blocks the spinal nerves at the paravertebral side ③ Directly penetrates the dura mater and arachnoid mater and acts on the surface of nerve roots and spinal cord
Blockade and plane of anesthesia
The effects produced after each nerve is blocked - analgesia; Sympathy - reduce visceral stretch reaction; Movement - muscle relaxation
The order in which each nerve is blocked: sympathetic > sensory > motor
The plane at which each nerve is blocked: sympathetic > sensory (2-4) > motor (1-4)
Anesthesia level: the range of skin pain loss measured by acupuncture after the sensory nerve is blocked
Effects of spinal anesthesia on the body
Respiration: mainly depends on the level of anesthesia, especially the range of motor nerve block
cycle
Sympathetic nerve block → peripheral vasodilation → decreased blood return to the heart → decreased blood pressure
Sympathetic block → vagal tone ↑ → bradycardia
Others: nausea and vomiting, urinary retention
Methods of spinal anesthesia
subarachnoid block
Classification
⑴According to the proportion of local anesthetic: heavy specific gravity solution, equal specific gravity solution, light specific gravity solution ⑵According to the anesthesia plane: high plane>T4>mid plane>T10>low plane ⑶According to the administration method: single method and continuous method
lumbar puncture
Position: lying on the side, flexion position or sitting position; puncture gap: adult L3-4 gap
Factors affecting the level of anesthesia
① local anesthetic dose ② drug volume ③ drug specific gravity ④ puncture gap ⑤ patient position ⑥ injection speed
complication
intraoperative complications
⑴ Drop in blood pressure ⑵ Respiratory depression ⑶ Nausea and vomiting
Postoperative complications
⑴ Headache ⑵ Urinary retention ⑶ Cranial nerve palsy ⑷ Adhesive arachnoiditis ⑸ Cauda equina syndrome ⑹ Suppurative meningitis
Indications: Surgery on the lower abdomen, pelvis, lower limbs and anus-perineum within 2-3 hours.
Contraindications
① Central nervous system diseases: meningitis, increased intracranial pressure, etc.; ② shock; ③ skin infection at or near the puncture site; ④ sepsis; ⑤ spinal trauma or tuberculosis; ⑥ acute heart failure or coronary heart disease attack
Epidural anesthesia
epidural puncture
(1) Position: side lying and flexion; (2) Puncture reach: hard external cavity; (3) Method: straight entry method, lateral entry method;
Indications: disappearance of resistance (feeling of loss), positive capillary negative pressure, no cerebrospinal fluid aspiration, and no resistance to gas injection. Catheter indwelling length: 3-4cm
Injection method
Test volume: 1%-2% lidocaine 3-4 ml, observe for 5 minutes for signs of spinal anesthesia. First dose: 2% lidocaine 7-10 ml
Adjustment of anesthesia level
①Local anesthetic volume ②Puncture gap ③Catheter direction ④Injection method ⑤Others: patient conditions, etc.
complication
intraoperative complications
① Total spinal anesthesia, ② Local anesthetic poisoning, ③ Blood pressure drop, ④ Respiratory depression, ⑤ Nausea and vomiting
Postoperative complications
① Nerve injury ② Epidural hematoma ③ Epidural abscess ④ Anterior spinal artery syndrome
Indications
Various abdominal, lumbar and lower extremity surgeries below the diaphragm as well as neck, upper extremity and chest wall surgeries
Contraindications
① Central nervous system diseases: meningitis, increased intracranial pressure, etc.; ② shock; ③ skin infection at or near the puncture site; ④ sepsis; ⑤ spinal trauma or tuberculosis; ⑥ acute heart failure or coronary heart disease attack
sacral block
Sacrocanal puncture: Position: lying on the side or prone, puncture point: sacral hiatus
Complications: local anesthetic poisoning, total spinal anesthesia
Indications: Rectal, anal and perineal surgery
Contraindications: Infection at the puncture site and sacral deformity
Perioperative testing and management
Monitoring and management during anesthesia
Respiratory function monitoring: respiratory type, amplitude, frequency and rhythm, PaO2, PaCO2, blood pH, SpO2 and ETCO2
Respiratory management: tongue drop, excessive secretions, aspiration and suffocation, laryngospasm and bronchospasm, operational errors
Circulatory function monitoring: blood pressure, heart rate, pulse, peripheral circulation, urine output, central venous pressure (CVP), pulmonary capillary wedge pressure (PCWP)
Others: consciousness, body temperature, electrolytes, blood sugar
Monitoring and management of anesthesia recovery period
Monitoring: ECG, BP, respiratory rate and consciousness, SpO2
Treatment of delayed awakening after general anesthesia:
Analysis of reasons: too deep anesthesia, residual muscle relaxants, liver and kidney dysfunction, low temperature, advanced age, electrolyte imbalance, high or low blood sugar
Treatment: Maintain ventilation, stabilize circulation, increase temperature, correct abnormalities, and antagonize anesthetic residues
Keep the respiratory tract open: suction, support the jaw, oropharyngeal airway; pressurize oxygen with a mask; open wounds in emergency situations
Keep circulation stable
Causes of hypotension: hypovolemia, venous return disorder, decreased vascular tone; decreased cardiac output, etc.
Causes of hypertension: postoperative pain, urinary retention, hypoxemia, hypercapnia, intracranial hypertension, hypertension
feel sick and vomit:
Cause: drugs, hypotension, etc.
Treatment: droperidol, metoclopramide, ondansetron
controlled blood pressure reduction
Methods that use drugs or/and anesthesia techniques to reduce and control arterial pressure at a certain level to facilitate surgical operations, reduce surgical bleeding, and improve hemodynamics. must be reversible
The basic principle
Ensure blood perfusion of tissues and organs to meet basic metabolic needs; mainly reduce peripheral vascular resistance
Blood pressure standard: SBP is not less than 80mmHg, or MAP is 50-65mmHg, or 30% lower than the basic blood pressure.
Position: Try to keep the surgical field in the highest position or lower limbs (15o)
Close monitoring: ECG, SpO2, urine output, BP, body temperature, CVP, arterial blood gas
method
⒈Inhalation anesthetics: suitable for short-term blood pressure reduction, ⒉vasodilators
Indications
① Reduce blood vessel tension to facilitate surgery, such as intracranial artery retention; ② Reduce blood leakage in the surgical field and reduce bleeding, such as hip joint and posterior fossa surgery; ③ Control blood pressure during anesthesia, such as myocardial ischemia and acute pulmonary edema
Contraindications
Serious organ disease (heart, brain, liver, kidney), acid-base imbalance, shock, and severe anemia
complication
Delayed awakening, reactive bleeding, postoperative blurred vision, acute renal failure, thrombosis
whole body hypothermia
Reduce the body temperature to a certain level in order to reduce the body's metabolism and maintain or delay the body's cell activity to meet the needs of treatment and surgery. Shallow low temperature: 36-34℃; Medium low temperature: 34-26℃; Deep low temperature <26℃
physiological effects
Early stage of cooling: mainly stress response, manifested as sympathetic excitement
Late stage of cooling: cerebral blood flow ↓ cerebral oxygen consumption ↓ intracranial pressure ↓ heart rate ↓ liver metabolism ↓
Indications
Extracorporeal circulation cardiovascular surgery, complex cranial surgery, brain resuscitation
physiological effects
Ice water immersion method, ice pack method, variable temperature blanket and extracorporeal circulation method; shallow hypothermia can be used under various anesthesia, and deep hypothermia is performed under general anesthesia