General Surgery
Mosul university- College of dentistry-oral & maxillofacial surgery departmentDr. Ziad H. Delemi B.D.S, F.I.B.M.S (M.F.)
General Anaesthesia In Dentistry
GENERAL ANAESTHESIA (G.A.)
Mosul university- College of dentistry-oral & maxillofacial surgery departmentGENERAL ANAESTHESIA (G.A.)
Anaesthesia: (an: no, aesthesia: sensation) so it is a reversible state of unconsciousness during which the reflex response to pain is abolished, &keep the patient a life & prepare optimal possible condition for surgery or diagnosis.Mosul university- College of dentistry-oral & maxillofacial surgery department
Indications of GA for dentistry:
Extent of surgery unsuitable for local anaesthesia. Lack of co-operation: young children, mentally or physically debilitated patients. Extreme nervousness, dental phobia. Local anaesthetic ineffective (infection) or contraindicated (allergy to local anaesthetic or vasoconstrictor).Mosul university- College of dentistry-oral & maxillofacial surgery department
Cardiac disease. Obstructive airways disease. Active or recovering respiratory tract infection. Upper airways obstruction. Diabetes. Anaemia. Obesity. Cerebrovascular disease. Pregnancy.
Contra-indications to outpatient GA:
Mosul university- College of dentistry-oral & maxillofacial surgery department
Assessment is by history, observation, physical examination + laboratory tests, hemoglobin level (Hb.), chest radiograph (CXR),electrocardiograph (ECG), blood group (B.Gp), general urine examination (G.U.E.), fast blood sugar (F.B.S.), serum electrolyte.
Preoperative assessment
Mosul university- College of dentistry-oral & maxillofacial surgery department
All patients should have starved of clear fluids for at least 2 hours and of solids for 6 hours prior to induction of anaesthesia, take shower & cleaning operated site & shaving the area of the operation if there is a hair, emptying bladder, Written consent must have been obtained from the patient, or parent or legal guardian.
Preoperative preparation
Mosul university- College of dentistry-oral & maxillofacial surgery department
I.V. canula as a peripheral line one or more, ECG leads and a pulse oximeter probe which measures oxygen saturation and pulse rate are attached, electocautery shield put under one of the legs, & always check drugs emergency kit.
Intraoperative preparation
Mosul university- College of dentistry-oral & maxillofacial surgery department
I.V. canula
Mosul university- College of dentistry-oral & maxillofacial surgery departmentAnaesthetic drugs
Mosul university- College of dentistry-oral & maxillofacial surgery departmentArtificial airway & IPPV
Mosul university- College of dentistry-oral & maxillofacial surgery departmentStage I Analgesia (cough reflex) Stage II Disinhibition excitation (bad stage) Stage III Surgical anesthesia (working stage) Stage IV Medullary depression (death stage)
Stages of General Anesthesia
Mosul university- College of dentistry-oral & maxillofacial surgery department
1- Sleep induction & loss of consciousness. Skeletal muscle relaxation. Intubation : Orotracheal, Nasotracheal, Tracheostomy Loss of pain responses( analgesia ). 2- Maintenance of anaesthesia 3- Recovery
Technique of general anaesthesia
PHASES OF ANAESTHESIA
Mosul university- College of dentistry-oral & maxillofacial surgery department
Premedications
Mosul university- College of dentistry-oral & maxillofacial surgery departmentSkeletal muscle relaxation drugs
It is used to get muscle relaxation for endotacheal intubation. 1- Depolarizing agents: Suxamethonium (scoline) rapid onset 45sec. Lasts for 5min, No need for antidot. 2- Non depolarizing agents: Tubocurarin (curari), Galamine long acting onset 3min. Lasts for 30 min. it need antidot cholinesterase inhibitor {Neostigmine}so Atropin is needed also.Mosul university- College of dentistry-oral & maxillofacial surgery department
1- Induction (rendering the patient unconscious)1-Inhalational induction: anaesthesia is induced with a mixture of gases, oxygen (minimum 30%) &nitrous oxide &one of the volatile anaesthetics (Halothane) the patient loses consciousness at which stage it is important to prevent airway obstruction with the tongue by lifting the jaw.2-Intravenous induction: following injection of one of the intravenous anaesthetic agents such as (propofol or Na+ thiopental or Ketamine) the patient becomes unconscious in 30-45s. All of these drugs cause respiratory depression and the patient’s respiration may need to be assisted after their use. PHASES OF ANAESTHESIA
Mosul university- College of dentistry-oral & maxillofacial surgery department
2-Maintenance of anaesthesia (keeping the patient unconscious) by inhalation of oxygen, nitrous oxide & vapour, usually Halothane in lower concentrations than those used at induction. However during dental surgery this cannot be given by a full face mask covering the mouth because the operator needs access to the mouth. This problem is overcome by using one of three methods: -Nasal mask Laryngeal mask Endotracheal intubation
PHASES OF ANAESTHESIA
Mosul university- College of dentistry-oral & maxillofacial surgery department
Monitoring the patient’s condition is of vital importance. The patient’s color & respiration & color of blood are observed. The pulse is felt. As well as the ECG & pulse oximetry the blood pressure is measured in longer cases, before starting the procedure put the pharyngeal pack. Monitoring
Mosul university- College of dentistry-oral & maxillofacial surgery department
3- Recovery At the end of the operation the inhaled anaesthetic mixture is replaced with 100% oxygen.. the pharyngeal pack should be removed, The patient is placed on their side with the head down and the jaw well supported. In the recovery area the patient is still at risk of airway obstruction, inhalation of blood/vomit , respiratory depression, arrhythmias and hypotension. Recovery must be supervised by trained staff who look after the patient continually until full consciousness occurs. All patients should be nursed in the recovery position with the jaw supported and with oxygen given by mask and a pulse oximeter attached until they awake. Suction must be available at all times.
Recovery
Mosul university- College of dentistry-oral & maxillofacial surgery department
1-Airway obstruction - caused by the tongue falling back or dental packs. In addition if foreign material touches the vocal cords they may go into laryngospasm. 2-Respiratory depression - all the commonly used anaesthetic drugs may cause respiratory depression. The anaesthetist must be ready to reduce the amount of anaesthetic or assist respiration wherever appropriate. 3-Inhalation of blood and debris - unconscious patient cannot protect their airway due to a depressed cough or gag reflex. The dental pack may not be properly placed or it may become soaked with blood & become ineffective.
Complications
Mosul university- College of dentistry-oral & maxillofacial surgery department
Complications
4-Arrhythmias (abnormal heart rhythm) - these were very common during dental extraction under halothane anaesthesia. 5-Hypotension (low blood pressure) - this is a side-effect of most anaesthetic drugs. The effect is lessened by anaesthetizing the patient in the supine position. Remember that problems associated with anaesthesia such as anaphylaxis, malignant hyperpyrexia, and post-operative nausea and vomiting may occur in the dental surgery too.Mosul university- College of dentistry-oral & maxillofacial surgery department
Rare, genetically susceptible Tachycardia, hypertension, hyperkalemia, muscle rigidity, and hyperthermia Due to massive release of Ca++ Treat with dantrolene (Dantrium), lower elevated temperature, and restore electrolyte imbalance
Malignant Hyperthermia
Mosul university- College of dentistry-oral & maxillofacial surgery departmentHalothane (Fluothane): Volatile liquid Narrow margin of safety Less analgesia and muscle relaxation Hepatotoxic Reduced cardiac output leads to decrease in mean arterial pressure Increased sensitization of myocardium to catecholamines (local anaesthesia carpol)
Major types of G.A. agents
Mosul university- College of dentistry-oral & maxillofacial surgery departmentKetamine (Ketalar): Dissociative anesthesia: analgesia, and amnesia without loss of consciousness Post-op emergence phenomena: disorientation, illusions, vivid dreams Cardiac stimulant