LA Sheet #11 By Valeria Manfalouti

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LA Sheet #11 By Valeria Manfalouti

Post by Sura on 25/12/2011, 10:39 pm

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Re: LA Sheet #11 By Valeria Manfalouti

Post by Shadi Jarrar on 31/12/2011, 6:13 am

Local anesthesia lec.11

21/12/2011

General anesthesia

Sensations

· Peripheral nervous system senses:

Pain, temperature, touch, proprioception, special senses

· Central nervous system( brain and spinal cord) mainly for awareness

Anesthesia according to the context of the term use

In surgery for example it reversibly renders the patient unconscious by drugs for execution of a painful operative procedure- in a titrable and controlled way.

The doc also repeated that what is in bold is the aim of anesthesia in surgery

Surgery

In general surgery is a trauma for the patient, and this trauma leads to stress on the living body.

Metabolic response to stress( how the body reacts to the trauma, incision,…)

1. Neural component: Autonomic system

a. Sympathetic: might lead to tachycardia/ hypertension

b. Parasympathetis

2. Endocrine Component(Hormonal response): usually response in GH, cortisol, glucagon, ADH, Renin - Aldosteron system, etc…

Anesthesia:

Ø Modulates the stress response by blocking the afferent limb of the response .

Ø Pain and awareness are blocked by anesthetic drugs , but other afferent limb factors are not ( e.g. Hypovolemia, hypoxemia, etc)

Drugs affect the pain but if u have other factors that might lead to stress such as hypovolemia and hypoxia, these wont be effected by the medication.

So we need to have complete medical management of the patient……Peri-operative Medical management ( which means: pre-…intra- op…and post-op)

Anesthesia in general have 3 mandatory components:

1. Hypnosis: The state of being asleep (Controlled loss of awareness)..there is special agent used during anesthesia for the induction of hypnosis during the procedure.

2. Analgesia: Pain killer, usually in anesthesia we use the opioids

3. Muscle relaxation: Not all the time we are in need for muscle relaxation during general anesthesia, but if we are in need, we should put the patient under controlled ventilation because when we give a muscle relaxant the patients respiratory system will be stopped; therefore, we need to support our patient with ventilator. In case if the muscle relaxant is not given the patient is left to breath spontaneously (especially during simple procedures).

Detailed:

Hypnosis:

· Pharmacologically induced by giving IV medication or inhalational agents during the procedure

Analgesia: state of freedom from pain

Brought by local or regional technique or drug with the general anesthesia ( to supply analgesia either by local infiltration, regional block, or general anesthesia through IV drugs which r the opioids)

Ø Local infiltration: (e.g. if there is a lipoma in the forearm and we want to do this under local anesthesia, we use infiltration for excision)

Ø Regional anesthesia: ( e.g. 1.a total knee replacement surgery, done by spinal anesthesia through the injection of anesthesia in the CSF(intra thecal), so we can induce analgesia and complete paralysis of the lower limb( from below the umbilicus) by regional anesthesia 2. Surgery in the hand, we do brachial plexus block (which blocks the upper limb))

Ø IV medication which is most commonly used esp. as general anesthesia

What are the opioids that can be used?

Methadine, Morphine, fentanyl, alfentanil, remifentanyl

But they have different potencies ( e.g. Morphine potency is *10 that of Methadine….fentanyl even stronger than morphine)

(Note: I heard it dozen of times and still heard it as Bethedine nt methadine….searched in the net nth was found so it is written with an M here)

The drug is chosen according to the pain

Most commonly used is fentanyl

Muscle relaxant:

Ø Paralyzing the patient’s muscles by use of drugs that block the acetylcholine receptors at the Neuromuscular junction

Ø Purposes:

a. Facilitation of airway management ( In standard situations, we do endo-tracheal intubation when doing general anesthesia, and this can’t be done without paralyzing the patient. In other situations we can give large doses of hypnosis and pain killers, and we can do intubation without relaxation BUT still the RULE : NO INTUBATION WITHOUT MUSCLE RELAXATION bcz the vocal cords are muscles, if not paralyzed, u might injure the vocal cord )

b. Control of Ventilation: using ventilator, tidal volume under a constant rate. The ventilator will show inspiratoy and expiratory…if the patient is not given a muscle relaxant and he is breathing while being connected to the ventilator , the patient will counteract the function of the ventilator…breath in with the ventilator …tidal volume of the breath + the 1 from the ventilator leads to irregular ventilation of the patient. Conclusion: for controlled ventilation we should give muscle relaxants

c. Facilitation of Surgery: ( e.g, in laparotomy, if the muscles of the abdomen are tight the surgeon wont be able to continue)

Patient should be artificially ventilated

Stages of anesthesia: ( usually these stages are not so clear bcz they are rapid)

1- Stage of analgesia:

Diminished pain perception, verbal contact

maintained, laryngopharyngeal reflexes (reflexes which protect the airway from aspiration)and

voluntary control Present ( reflex is so important bcz if we blunt the reflex we should protect the airway)

2- Stage of uninhibited response (Excitement):

Consciousness lost, verbal contact and voluntary

control lost (uncontrolled, exaggerated, withdrawal

type response to any stimulus)

3- Stage of Surgical Anaesthesia: ( we usually reach this stage in general anesthesia)

Ø Centers of the medulla become progressively depressed

Ø It is the stage at which anaesthesia has depressed both the reticular activating system and perhaps selectively the pain synapses of the spinal cord and is the stage at which operations may be performed

4- stage 4: usually we don’t reach this stage bcz it ends with multiple problems such as: cardiac arrest ,anoxia, arrhythmias, danger of death

Note: if we need deep anesthesia ( general anesthesia) we reach stage 3, if only sedation we reach stage 2..

Anesthesia in Dentistry:

Local anesthesia

Sedation (e.g. extraction of wisdoms)

General anesthesia( e.g. major surgery like mandibular fracture)

Dental procedures requiring sedation or general anesthesia:

1.Oral surgery:

- Removal of impacted teeth

- Multiple Dental extractions

- Preprosthetic Surgery (Vestibuloplasties)

- Insertion of Osteointegrated plants

2.Restorative dentistry:

- Multiple dental restorative procedures

(e.g.Rampant Caries)

- Procedures performed on Mentally Retarded Patients

3.TMJ:

Arthroscopy, Arthroplasty

4.Maxillofacial surgery:

Trauma, tumor and reconstructive surgery.

5.Special patient groups:

- Young Children esp. some with systemic Diseases (hemophilia( to control the hemostasis),CHD)

- Mentally retarded

- Patients with poorly controlled Seizure activity

- Those with an oral septic focus

Problems related to dental anesthesia:

1. In/outpatient selectivity..(most of the procedures are done outpatient because they are simple, but if there is a big surgery it is done inpatient bcz the patient should be sent to the intensive care post op. as there is a big manipulation of the airway …they have big edema in the airway and there is possibility of airway obstruction in the post op . period.

2. Competition for airway by both dentist and anesthetist…as anesthetist we care about endo-tracheal intubation…but we faced lots of problems with the surgeons while they are caring out the procedure they cut the tube by the chisel for example…

3. Patients are often children or mentally handicapped patients

How do we perform the general anesthesia??

1st we should prepare the patient and do the Pre-Operative assessment

-history: medical problems, surgical problems, anesthesia problems and allergy( e.g. for penicillin).

- Medical examination

- Investigations depending on the case ( e.g. patient wants to do a simple wisdom extraction and he came as an outpatient, what type of investigation should we do??? CBC…just in case if we faced any problem to know how to manage it

e.g. patient with heart problem( valve replacement) takes warfarin and wants to do multiple extractions, what we need to do??....INR=2, CBC, electrolyte, ECO( to asses the cardiac function), ECG, chest X-ray….instead of us doing all of this we ask for a cardiology consult. …Does he need prophylactic antibiotics??...Yes, to avoid bacterial endocarditis.

If INR=2.5…u should control the coagulation status of the patient, stop the warfarin for at least 3 days and repeat the INR…but now there is a risk of thrombus formation bcz he has mechanical valve…so u should admit the patient to the hospital give him heparin , stop warfarin and before the patient goes to the surgery we stop heparin bcz it is a short acting anticoagulant (6 hrs b4 the surgery the heparin is stopped)after the surgery continue with warfarin and heparin till the action of warfarin gets back.

- Informed consent: signed by the patient or guardian.

We should decide if the patient is under risk: (numbers show the mortality rate)

Ø ASA I : A normal Healthy patient 0.06-0.08%

Ø ASA II : A patient with mild systemic disease 0.27-0.40%

e.g. 40 yrs old diabetic patient taking oral hypoglycemic drugs, FBS is controlled, Hba1c is normal…so the disease is controlled

Ø ASA III: A patient with severe systemic disease 1.8 - 4.3%

e.g. a 70 yrs old patient, who is diabetic , have high blood pressure and ischemic heart disease with ejection fraction 35 , Hba1c=10, Blood sugar 170/100..this patient is not well controlled

ejection fraction: is the fraction of blood pumped out from the ventricles. normal =60%...if it was low then the patient has heart failure so the patient is risky

Ø ASA IV: A patient with severe systemic disease that is a constant threat to life (e.g. diabetes, hypertension with ejection fraction 25 and came to do laparoscopic colectomy 7.8 - 23%

Ø ASA V: Moribund patient who is not expected to survive without the operation( e.g. 70 yrs old patient with atrial fibrillation, IHD,hypertensive,diabetic,complete gangrenous bowel due to mesenteric thrombosis …so suspect that the patient will die during 24hrs either we did the operation or not 9.4-51%

Ø ASA VI: A declared brain dead patient whose organs are being removed for donor purposes(usually used for transplantation)

Ø “E” For Emergency surgery

e.g. ASA I E…. patient is healthy but came for appendectomy…so we cant wait for this case so we put the E.

Q:70 yrs old patient with dental abscess, they wrote his name in the emergency and the patient is diabetic and hypertensive BP 160/100 FBS 185??!!

ASA III E

If the same patient had FBS 400…BP 200/120 then ASA IV E





2nd Intra-operative management

- Establishing monitoring: heart rate, non invasive Blood pressure(cuff), ECG,Pulse oxymetry, End tidal CO2 monitor ( expired CO2) it shows that we did a proper intubation ( e.g. if by mistake the tube was put in the esophagus instead of the trachea the monitor wont give any reading)….also we can know if we have enough ventilation . Normal arterial CO2 40 mmHg ±4 while the end tidal CO2 is less than the arterial CO2 by3- 5 mm Hg ( e.g. end tidal volume 33 is normal)

Hyperventilation will show less end tidal CO2 e.g. 27mmHg

Hypoventilation will show higher end tidal volume e.g. 43mmHg

Check slide 25 in the H.O( ascending is for expiration and descending for inspiration)

Note: invasive BP when we put arterial line and connect it to a monitor which is used in certain operations

3rd Post-operative management

Maintenance of Anestheisa:

- Intravenous drug infusion for short acting

drugs

- Inhalational Agents for Hypnosis:

(e.g. Halthane,Sevoflurane,Isoflurane , Enflurane,desflorane, Nitrous Oxide, etc.. )

- Intermittent doses for intermediate or long acting muscle relaxants and analgesics ( bcz they have a certain half life and if not maintained the patient will feel pain after time)

Securing the airway:

We use endotracheal Cuffed tube and we insert it through the oral cavity or nasally ( why nasally is used?? Bcz in oral surgey we need the oral cavity to be empty for better vision)

Through the pilot we can blow the cuff, in this way it secures the airway from aspiration.


















Sometimes we use the laryngeal mask airway :

- Have different sizes just like the endotracheal tube

- Can be used in children and adults ( as endotracheal tube)

- The idea is that we enter it blindly without using the laryngoscope while the endotracheal tube should be entered under vision

- It cannot completely protect the airway , so it might not prevnt the aspiration

- Usually it is used for spontaneously breathing patients not for controlled ventilation

Intra- operative issues:

Ø Loose Teeth

Ø Surgical Debris

Ø Bleeding

Ø Secretions

Ø Use of Throat Pack (prevent debris and secretion to go down)

Ø Endocarditis Prophylaxis

Post – operative period:

- Patient should go to the recovery room….keep the patient in lateral position to prevent secretions from going back

- Anti-dote for muscle relaxant is Neostigmine

- Monitor the patient in the recovery room

- Assessment of patient before discharge

- We can manage some complications like giving painkillers in case of pain

- prescribing oral analgesic drugs if patient is sent home

- Advice NOT to Drive or operate machinery for 24 hours at least







END

Done by: Valeria Manfalouti

Good luck J
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Shadi Jarrar
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