 Home > Active Ingredient News > Anesthesia Topics > Do not be careless about local anesthesia, and be wary of systemic toxicity!

Do not be careless about local anesthesia, and be wary of systemic toxicity!

 Last Update: 2021-11-11
 Source: Internet
 Author: User

Tags

black rice diabetes

2 4 label

Search more information of high quality chemicals, good prices and reliable suppliers, visit www.echemi.com

Local anesthesia systemic toxicity (LAST) is still common in clinical practice

01 LAST risk factors and risk assessment 01 LAST risk factors and risk assessment

LAST risk factors and risk assessment as in FIG.

Figure 1Risk assessment of patient factors and local anesthesia technology factors LAST

Figure 1The risk assessment of patient factors and local anesthesia technology factors LAST Figure 1

Note: (a) the use of low-dose or low-lipophilic local anesthetics, the risk of ultrasound-guided nerve block; (b) the use of high-dose or high-lipophilic local anesthetics without ultrasound guidance

Local anesthetics

Local Anesthetic Drugs Local Anesthetic Drugs

Increased fat solubility of local anesthetics will lead to increased cardiotoxicity, and also reduce the dose ratio of local anesthetics to arrhythmia and convulsions (CVS/CNS ratio)

dose

Dose dose

The maximum recommended dose of local anesthetics based on ideal body weight can be used to guide the dosage of local anesthetics.

It is worth noting that when the airway is locally infiltrated, the anesthetic is absorbed by aerosol, or the effective drug that eliminates the metabolism and enters the blood circulation through the first pass is significantly reduced, so the maximum limit may be different

Similarly, tumescent anaesthesia combines high-dose (55mg/kg) lidocaine with epinephrine or other drugs.

Studies have shown that the peak of drug absorption of this technology may be 20 hours after injection, so special attention should be paid to outpatient use

Anesthesia site

Anesthesia site anesthesia site

Recent LAST case reports show that the incidence of paravertebral nerve block LAST is the highest .

In clinical practice, paravertebral, intercostal and interpleural block are all high-risk sites for LAST , and continuous catheter infusion of local anesthetics can increase the risk of LAST due to drug accumulation
.
Intrasacral canal, epidural, brachial plexus block and subcutaneous injection of local anesthetics have low blood concentrations, so LAST is not common
.
With the promotion of fascial plane block and ultrasound, the incidence of LAST has decreased
.
Paravertebral, intercostal and interpleural blocks are all high-risk sites for LAST

Existing technology and monitoring methods

Existing technology and monitoring methods

Existing technology and monitoring means Existing technology and monitoring means

Ultrasound-guided nerve block reduces the risk of local anesthetics entering the blood, and reduces the incidence of local anesthetics LAST by nearly 4 times
.
In addition to ultrasound assistance, the use of 3-5ml test doses, withdrawal before injection, and adjuvant adrenaline may also reduce the incidence of LAST
.

Ultrasound-guided nerve block reduces the risk of local anesthetics entering the blood, and reduces the incidence of local anesthetics LAST by nearly 4 times
.
In addition to ultrasound assistance, using a test dose of 3-5ml, withdrawing before injection, and adjuvant adrenaline may also reduce the incidence of LAST
.
Ultrasound-guided nerve block reduces the risk of local anesthetics entering the blood

Being awake does not reduce the risk of LAST.
Because the performance of the central nervous system of LAST cannot be monitored by conventional ECG monitoring, the patient may be aware of LAST earlier when awake, so that LAST can be detected earlier, and the anesthesia should be stopped as soon as possible and treated in time
.

age

Age age

Newborns, infants and the elderly are known to be high-risk groups for LAST
.

Newborns, infants and the elderly are known to be at high risk for LAST
.
Newborns, infants and the elderly are known to be high-risk groups for LAST
.

Cardiovascular diseases

Cardiovascular diseases

Cardiovascular disease, cardiovascular disease

Patients with decreased cardiac contractility, abnormal conduction, or previous arrhythmia, myocardial ischemia, or insufficient cardiac output are the high-risk population of LAST, and the severity may also increase
.

Pregnancy

Pregnancy

Pregnancy pregnancy

During pregnancy, the alpha-1 acid glycoprotein decreases and the cardiac output increases, leading to the rapid absorption of free local anesthetics into the blood, and the blood concentration increases
.
Elevated progesterone increases the sensitivity of nerves to local anesthetics, so high block is prone to occur
.
In addition, the reduction in the volume of the epidural and subarachnoid space means that the dose of local anesthetics should be reduced accordingly
.
Therefore, pregnant women should pay special attention to the dose of local anesthetics and use the smallest effective dose of local anesthetics
.

Liver and kidney disease

Liver and kidney disease

Liver and Kidney Diseases Liver and Kidney Diseases

When hepatic blood flow is reduced or liver function is impaired, the metabolism of amide local anesthetics (lidocaine, ropivacaine, etc.
) slows down
.
In liver failure, ɑ-1 acid glycoprotein can still be synthesized, and it may be accompanied by uremia and acidosis.
Therefore, the blood concentration of local anesthetics increases and the risk of LAST increases
.

Metabolic disease

Metabolic disease

Diabetes , mitochondrial diseases, carnitine deficiency, and malnutrition are considered risk factors for LAST
.
Women seem to have a higher risk of disease than men
.

Diabetes , mitochondrial diseases, carnitine deficiency, and malnutrition are considered risk factors for LAST
.
Women seem to have a higher risk of disease than men
.
diabetes

Non-operating room nerve block

Non-operating room nerve block

Nerve block in non-operating roomNerve block in non-operating room

Stomatology, pain medicine, urology, dermatology, and emergency departments often require local anesthesia and nerve block.
When the patient has neurological and cardiovascular changes, especially progressive hypotension, bradycardia or cardiac arrest, be alert LAST, stop the drug in time and give corresponding treatment
.
Especially in the case of progressive hypotension and bradycardia or cardiac arrest, you should be alert to LAST, stop the drug in time and give corresponding treatment
.

02 LAST prevention measures

02 LAST prevention measures 02 LAST prevention measures

The solutions for LAST risk factors are shown in Table 1
.

The solutions for LAST risk factors are shown in Table 1
.
Table 1

Table 1 Prevention plan for LAST risk factors

Table 1 Prevention plan for LAST risk factors Table 1 Prevention

Selection of local anesthetic drugs and methods

Selection of local anesthetic drugs and methods

Selection of local anesthetic drugs and methods Selection of local anesthetic drugs and methods

Try to choose the least cardiotoxic local anesthesia (such as lidocaine) or the method that requires the lowest dose of local anesthesia (such as intraspinal anesthesia)
.

Blocking factors

Blocking factors

Blocking factor Blocking factor

Dosage: Individuals evaluate the administered dose and use 95% of the minimum effective dose (ED95) as much as possible while ensuring the duration of anesthesia and analgesia
.
High-risk populations (children and populations with low local anesthetic clearance) need to be closely monitored during repeated administration or continuous catheter administration
.

Location: Adjuvant adrenaline is applied to the high-risk areas of LAST to reduce local anesthetics into the blood
.

Location: Adjuvant adrenaline is applied to the high-risk areas of LAST to reduce local anesthetics into the blood
.
Location:

Existing technical factors: ultrasound guidance can significantly reduce the risk; use of test doses; withdrawal of drugs; auxiliary application of epinephrine; use of NRFit technology; early detection of LAST in conscious patients; avoiding excessive sedation
.

Patient factors: Children, liver and kidney dysfunction, and patients with metabolic diseases should reduce the dose of local anesthetics.
Those with cardiovascular disease, especially severe ventricular dysfunction, should also reduce the dose, or even avoid nerve block
.
For the elderly, it should be reduced by 10%-20%; pregnant women should use the minimum effective dose of local anesthetics
.

Other non-technical factors

Other non-technical factors

Other non-technical factors Other non-technical factors

Training of LAST-related knowledge for medical staff, including assessment of high-risk groups, LAST clinical manifestations, treatment plans, and LAST first aid kits; avoiding the combined use of multiple local anesthetics or techniques; avoiding excessive local anesthetics during the perioperative period
.

It is worth noting that about 53% of LAST occurred within 10 minutes after administration, 19% occurred within 1 hour after administration, 8% occurred within 1-12 hours after administration, and 8% occurred within 10 minutes after administration.
After the last 12 hours, 11% did not report the time of onset
.

35% of patients showed dual effects of central nervous system symptoms including dizziness, tinnitus, numbness of the mouth and tongue, muscle twitches, convulsions, and disturbances in consciousness, as well as cardiovascular symptoms such as circulatory abnormalities .
32% had only central nervous system symptoms, 24 % Manifested only as cardiovascular symptoms
.

35% of patients showed dual effects of central nervous system symptoms including dizziness, tinnitus, tongue and tongue numbness, muscle twitching, convulsions, disturbances of consciousness, etc.
and cardiovascular symptoms such as circulatory abnormalities , 32% only had central nervous system symptoms, 24 % Manifested only as cardiovascular symptoms
.
35% of patients showed dual effects of central nervous system symptoms including dizziness, tinnitus, numbness of the tongue, muscle twitches, convulsions, disturbance of consciousness, and cardiovascular symptoms such as circulatory abnormalities

When LAST occurs, the administration should be stopped immediately and effective airway management and fluid resuscitation should be carried out.
Fat emulsions should be infused early to prevent hypoxia and hypercapnia (factors that exacerbate LAST).
If respiratory and cardiac arrest occurs, it should be immediately For cardiopulmonary cerebral resuscitation, the use of large doses of epinephrine can increase the success rate of cardiopulmonary cerebral resuscitation
.

03Future development direction

03 Future Directions 03 Future Directions

Suggestions for future improvements of LAST are shown in Table 2
.

Suggestions for future improvements of LAST are shown in Table 2
.
Table 2

Table 2 LAST improvement direction

Table 2 LAST improvement direction table 2

Medical education: conduct LAST related courses and professional training for anesthesiologists, surgeons and nursing staff, and conduct multi-disciplinary simulation training
.

Medical education: conduct LAST related courses and professional training for anesthesiologists, surgeons and nursing staff, and conduct multi-disciplinary simulation training
.
Medical education:

Medical system: Design an electronic drug chart that can automatically calculate the maximum safe dose; design a computerized automatic alarm system for drug overdose; develop a non-operating room LAST treatment guide
.

Novel techniques include a local anesthetic dose restriction technologies; novel apparatus for intravascular injection needle can be detected; treatment algorithms research international standardization
.

Drug improvement : In addition, some physical or chemical treatments of the existing more toxic local anesthetics can ensure the local anesthetic/analgesic effect while prolonging the action time of the local anesthetics and reducing systemic toxicity.
It is also an improvement direction
.

references:

Macfarlane AJR, Gitman M, Bornstein KJ, et al.
Updatesin our understanding of local anaesthetic systemic toxicity: a narrative review[J]Anaesthesia.
2021 Jan;76 Suppl 1:27-39.

Macfarlane AJR, Gitman M, Bornstein KJ, et al.
Updatesin our understanding of local anaesthetic systemic toxicity: a narrative review[J]Anaesthesia.
2021 Jan;76 Suppl 1:27-39.

Leave a message here

This article is an English version of an article which is originally in the Chinese language on echemi.com and is provided for information purposes only. This website makes no representation or warranty of any kind, either expressed or implied, as to the accuracy, completeness ownership or reliability of the article or any translations thereof. If you have any concerns or complaints relating to the article, please send an email, providing a detailed description of the concern or complaint, to service@echemi.com. A staff member will contact you within 5 working days. Once verified, infringing content will be removed immediately.