Principles of Anesthesia Week 1 Lecture Notes 3.docx

Principles of Anesthesia Week 1 Lecture Notes Introduction to Anesthesia - **Breadth of Specialty** - Obstetric - Pediatric - Cardiothoracic - Neuro - Outpatient - Pain management - Critical Care - **Types of Anesthesia** - General anes...

Principles of Anesthesia Week 1 Lecture Notes Introduction to Anesthesia - **Breadth of Specialty** - Obstetric - Pediatric - Cardiothoracic - Neuro - Outpatient - Pain management - Critical Care - **Types of Anesthesia** - General anesthesia - Monitored Anesthesia Care (MAC) - Regional Anesthesia - Local Anesthesia - **Ideal Anesthetic Technique** - Optimal patient safety - Patient satisfaction - Excellent operating conditions for surgeon - Allow rapid recovery - Avoid postoperative side effects - Low cost - Early discharge or transfer from PACU (cost) - **Considerations that influence the choice of anesthetic technique** - Patient safety - Patient comfort - Preference - Coexisting conditions - Surgical site - Positioning - Elective vs emergency - Airway - Duration of surgery - Patient age - Recovery time - Post anesthesia care unit discharge criteria - General Anesthesia - Loss of consciousness is the start of general anesthesia - Broad definition- drug induced depression of the CNS resulting in the loss of response to and perception of all external stimuli - ASA continuum of sedation - Is a drug-induced loss of consciousness during which patients are not arousable, even by painful stimulation - Components of Anesthetic State - Unconsciousness - Amnesia - Analgesia - Immobility - Attenuation of autonomic responses to noxious stimulation - General anesthesia all these components are present. In sedation some components will be provided. Things like immobility may not be present. - Phases of general anesthesia - Induction - Maintenance - Emergence - General Anesthetic Type - Inhalation Only - Common in children and some dental procedures - Intravenous Only (aka TIVA) - Total IV anesthetics. - Patient indications - Severe refractory post op nausea - MAC sedation anesthetics - Neuro spine surgery (inhalation drugs may be contraindicated b/c of monitoring devices. Also may increase ICP. - Combination Inhalation/ IV (Balanced Anesthesia) - Most common in modern anesthesia practice - Induction Sequence - Room setup, machine check - SAM TIDE checklist - Suction - Airway - Machine - Tape - IV - Drugs - Equipment - Apply monitors - Patient positioning - Baseline vitals - To provide reference - Possible stop point prior to proceeding - Preoxygenation - Administration of induction agents (IV, inhalation, combination) - Eyelid reflex - Mask ventilation - Neuromuscular blocking agents (+/-) - Airway instrumentation - Pre-induction Monitors - Routine Monitors - ASA standard monitors should be used as minimum standards for all anesthetic techniques. - Special monitors - Consider additional monitoring such as arterial lines when consistent and continuous monitoring of BP needed - Consider CVP - Risk for bleeding, or need to monitor CVP to guide intraoperative fluid management. - Other monitors to consider - BIS, EMG-SSEP, MEP, cerebral oximeter, TEE, Swan-Ganz, clear-Sight, Flo Trac. (do not need to know definitions below, just additional info for future) - EMG- electromyography is used to monitor spontaneous muscle activity or evoked compound muscle action potentials (CAMPs). This is used to monitor nerve integrity in surgery. - SSEP- Somatosensory Evoked Potential is an intraoperative neurophysiological monitoring test that monitors nerve pathways that are responsible for feeling pressure, touch, temperature and pain. - MEP- Motor Evoked Potential is a monitoring modality that offers monitoring of the motor system through transcranial electrical stimulation of the motor cortical structures and recording of myogenic responses in the target muscle groups. - DO NOT MOVE PATINET ON BED UNTIL PATIENT IS STRAPPED DOWN. - TQ- How many breaths are needed for a positive co2? 3 breaths - \*\*ASA & AANA Standards of Care\*\* TQ's - American Society of anesthesiologists - standard one - Qualified anesthesia personnel shall be present in the room throughout the conduct of all general anesthetics, regional anesthetics and monitored anesthesia care. - - Standard 2 - During all anesthetics, the patient\'s oxygenation, ventilation, circulation and temperature shall be continually evaluated. - Oxygenation - To ensure adequate oxygen concentration and the inspired gas and the blood during all anesthetics - Inspired gas - during every administration of general anesthesia using an anesthesia machine, the concentration of oxygen in the patient\'s breathing system shall be measured by an oxygen analyzer with a low oxygen concentration limit alarm and use - Blood oxygenation - During all anesthetics a quantitative method of assessing oxygenation such as pulse oximetry shall be employed. When the pulse oximeter is utilized the variable pitch pulse tone and low threshold alarm shall be audible to the anesthesia provider. - Ventilation - Every patient receiving general anesthesia shall have the adequacy of ventilation continually evaluated. - Qualitative clinical signs such as chest excursion, observation of the reservoir breathing bag and auscultation of breath sounds are useful. - When an endo tracheal tube or laryngeal mask is inserted, correct positioning must be verified with clinical assessment and by identification of carbon dioxide. - continual end title carbon dioxide analysis from the time of endotracheal tube/ laryngeal mask placement until extubation or initiating transferred to a postoperative care location shall be performed using a quantitative method such as capnography, capnometry or mass spectroscopy - Shall be a continuous use of a device that is capable of detecting disconnection of components of the breathing system - During regional anesthesia or local anesthesia with no sedation the adequacy of ventilation shall be evaluated by continual observed observation of qualitative clinical signs. For deep sedation adequacy of ventilation shall be observed by qualitative clinical signs and observing for the presence of exhaled carbon dioxide. - Circulation - Every patient receiving anesthesia shall have the electrocardiogram continuously displayed from the beginning of anesthesia it\'s appearing to leave the anesthetizing location. - every patient receiving anesthesia shall have arterial blood pressure and heart rate determined it evaluated at least every five minutes - circulatory function continuously evaluated by at least one of the following palpitation of a pulse, auscultation of heart sounds, monitoring of a tracing of intra-arterial pressure, ultrasound peripheral pulse monitoring, or pulse plethysmography or oximetry. - body temperature - every patient receiving anesthesia shall have temperature monitored when clinically significant changes in body temperature intended, anticipated or suspected. - AANA standards for nurse anesthesia practice - standard one - perform and document a thorough preanesthesia assessment and evaluation - standard 2 - obtain and document informed consent for the planned anesthetic intervention from the patient or legal guardian, or verify that informed consent has been obtained and documented by a qualified professional - standard 3 - formulate a patient specific plan for anesthesia care - standard 4 - Implement and adjust the anesthesia care plan based on the patient\'s physiologic status. continuously assess the patient\'s response to the anesthetic, surgical intervention, or procedure. Intervene as required to maintain the patient and optimal physiologic condition. - standard 5 - monitor, evaluate, and document the patient\'s physiologic condition as appropriate for the type of anesthesia and specific patient needs. When any physiological monitoring device is used, variable pitch and threshold alarms shall be turned on and audible. The crna should attend to the patient continuously until the responsibility of care has been accepted by another anesthesia professional. - Oxygenation - continuously monitor oxygenation by clinical operation and pulse oximetry. If indicated, continually monitor oxygenation by arterial blood gas analysis. - Ventilation - continuously monitor ventilation. Verify intubation of the trachea or placement of other artificial airway devices by auscultation, chest excursion, and confirmation of expired carbon dioxide. Use ventilatory pressure monitors as indicated. Continuously monitor end title carbon dioxide during controlled or assisted ventilation and any anesthesia or sedation technique requiring artificial airway support. During moderate or deep sedation, continuously monitor for the presence of expired carbon dioxide. - Cardiovascular - continuously monitor cardiovascular status via electrocardiogram. Perform auscultation of heart sounds as needed. Evaluate and document blood pressure and heart rate at least every five minutes. - thermoregulation - when clinically significant changes in body temperature are intended, anticipated, or suspected, monitor body temperature in order to facilitate the maintenance of normothermia. - neuromuscular - when neuromuscular blocking agents are administered, monitor neuromuscular response to assess depth of blockade and degree of recovery. - Positioning - monetary and assess patient positioning and protective measures, except for those aspects that are performed by exclusively by one or more other providers. - Standard six - document pertinent anesthesia related information on the patient\'s medical record in an accurate, complete, legible, and timely manner. - standard 7 - evaluate the patient status and determine when it\'s safe to transfer the responsibility of care period accurately report the patient\'s condition, including all essential information, and transfer the responsibility of care to another qualified health care provider in a manner that assures continuity of care and patient safety. - standard 8 - adhere to appropriate safety precautions as established within the practice setting denies their risks of fire, explosion, electric and equipment malfunction. When the patient is ventilated by an automatic mechanical ventilator, monitor the integrity of the breathing system with a device capable of detecting a disconnection by emitting an audible alarm. When the breathing system of an anesthesia machine is being used to deliver oxygen, the crna should monitor inspired oxygen concentration continuously with an oxygen analyzer with a low concentration audible alarm turned on and in use. - Standard 9 - Verify that instructional policies and procedures for personnel and equipment exists within the practice setting. Adhered to infection control policies and procedures as established within the practice setting to minimize the risk of infection to the patient, the crna, and other health care providers. - Standard 10 - participate in the ongoing review and evaluation of anesthesia care to assess quality and appropriateness. - Standard 11 - respect and maintain the basic rights of patients. - Pre-induction preoxygenation - Oxygen application prior to administration of induction sequence - To replace nitrogen in patients' functional residual capacity (de-nitrogenation) - What is the percent O2 in room air? 21% - Why preoxygenation? - Have patient breathe 100% O2 via face mask for a period of 3-5 minutes - 8 vital capacity breaths. - Preoxygenation is especially important in patient's who are a difficult intubation - VENTILATION IS MORE IMPORTANT THAN INTUBATION - Vital capacity= max inhalation and max exhalation - Induction - Administering anesthetic drugs (inhaled or IV) to induce a state of anesthesia - Inducing a state of unconsciousness - Typically induction of General Anesthesia - Intravenous induction of anesthesia - A single ideal intravenous anesthesia induction drug has yet to be developed. However, propofol is pretty close. - Desirable properties for induction agents: - Rapid and smooth onset and recovery - Analgesia - Minimal cardiac and respiratory depression - Antiemetic actions - Lack of toxicity or histamine release - Advantages pharmacokinetics and pharmaceutics - Iv induction: produces a rapid onset of unconsciousness - commonly used anesthetic drugs: - propofol (most commonly used)(sedative hypnotic) - Thiopental (barbiturate) - Brevital (barbiturate) (used for induction, good for ECT (refractory depressive disorder) - Etomidate GABA mimetic/ sedative hypnotic - Ketamine (IV/IM) NMDA receptor antagonist- dissociative - Benzodiazepines - Generally used for adult patients or patients with preexisting IVs - Rapid Sequence Induction of Anesthesia- NO POSITIVE PRESSURE VENTILATION - Intravenous injection of an anesthetic to produce unconsciousness followed immediately by a neuromuscular blocking drug that produces a rapid onset of skeletal muscle paralysis. - cricoid pressure applied prior to loss of consciousness - what situation would necessitate an RSI? - full stomach or high-risk aspiration - trauma patient with unknown NPO status - diabetic with gastro paresis - most common cause of inability to ventilate is the obstruction of soft tissues such as the tongue or the tonsils. - patients with beards or no teeth can be difficult to ventilate - RSI sequence of events - Induction - assess for loss of consciousness - paralytic - DO NOT ventilate!!!!!!!!!!!!! - airway - Post Induction - Ventilation - After loss of consciousness, the anesthetist maintains airway using positive pressure ventilation - with face mask (+/- oral airway) - In what ways can we assess the quality of our ventilation? - Chest rise - Checking for CO2 (end tidal) - Fog in mask - Ease of ventilation - When you squeeze the bag, you are also assessing for lung compliance - Assess for ability to ventilate before giving paralytics - Airway instrumentation - Laryngeal mask airway (no paralytics) - Patient resumes spontaneous ventilation - endotracheal tube - endobronchial tube (one lung ventilation) - Are there exceptions to performing ventilation after induction? - No positive pressure ventilation for RSI patients - Inhalation induction - Most common method for inducing children in Northern American, scheduled for elective case. Why? - Because kids do not typically have an IV to perform IV induction - Also known as mask induction - +/- Mix of 70% Nitrous Oxide and 30% oxygen - Nitrous is a sweet gas so it makes it desirable to children - Desflurane vs. Sevoflurane - Sevoflurane nonpungent & not an irritant. It also helps reduce salivation - Steps - Prime circuit - Monitors (primarily pulse ox) - Mask application- administration of O2/NO2/Sevo - Loss of consciousness - Ventilation (Mask) vigilant monitoring of adequate exchange/ ventilation - PIV placement - Airway Instrumentation (LMA/ETT) - Verify placement - Maintenance - Defined as the management of physiological functions and the maintenance of surgical anesthesia following induction and until emergence - Goals: - Maintain surgical anesthesia - Maintain physiologic homeostasis - Monitoring is needed to ensure that these goals are met - Remain vigilant - Assess adequate ventilation - Do not induce a pediatric patient without someone else present with you - Child with full stomach and needs RSI do not use inhaled anesthetics. Give IV or delay the surgery if it can be delayed. - Provide: unconsciousness, amnesia, analgesia, immobility, muscle relaxation, and control of the sympathetic nervous system response to noxious stimuli (generally talking about a general anesthetic). - Accompanied by a combination of drugs - Inhaled and IV- with or without neuromuscular blockade (procedure dependent) - Drugs administered on basis of specific goal relevant to pharmacologic effect - Prevention of intraoperative awareness - Always requires vigilance of the provider - Incision, manipulating the uterus, etc are all very stimulating - Resecting bowel is not very stimulating - Stimulation will require adjustment in anesthetic depth - Assess need for blood - Maintenance of physiologic homeostasis - Maintain euvolemia for normotensive patients - Fluid management - 4-2-1 rule - Replace fluid - Monitor/chart/estimate and replace blood loss - Monitor urine output - Insensible fluid loss (must replace) ie. Evaporation - Titrate administer and redose medications as necessary (within 20 points of baseline) (critical for patients with uncontrolled hypertension they are left shifted they need higher perfusion pressures to perfuse their organs). - Maintain positioning and monitor pressure points - Positioning can affect maintenance. May need higher ventilation pressures. Consider increased or decreased venous return. - Ventilation - Many points for disconnection on the ventilator - Prevent hypothermia - Stay vigilant - Oxygenation - Vital signs - Anesthetic depth - Level of muscle relaxation - Positioning - Monitoring (standards) - 4-2-1 Rule - Fluid management - 4-2-1 is the hourly maintenance rate - 40+ patient weight in Kilos if patient is over 20kg - Replacement: ½ in first hour, ¼ in second and third hour - Stages of general anesthesia - Analgesia - Delirium - Surgical Anesthesia - Overdose  - Stage 1: Analgesia - Begins with administration of induction agents - Ends with loss of consciousness - Patients response to pain is altered - Stage 2: Delirium - Begins with loss of consciousness - Period of excitation and involuntary movement - In teenagers stage II will look like awake but their movements are non-purposeful. They cannot follow commands. - Signs: - Irregular respirations - Periods of apnea, breath holding - Dilated pupils and divergent gaze - Tachycardia - Hypertension - Delirium - In inhalation induction you will see delirium however, in IV induction you will not see stage II. Your patient will go from stage 1 to stage 3 - Stage 3: Surgical Anesthesia - Begins with onset of regular breathing pattern - Ends with loss of spontaneous respirations - Deep sleep not subject to rousing - Consists of four planes - Most surgical procedures can be safely performed in stage III: planes 1 and 2 - In inhalation - Goes from stage 1 to 2 to 3 - In IV induction - Goes from stage 1 to 3 - We create apnea - **Surgical Anesthesia: Stage 3 plane 1** - Loss of lid reflex - Respirations regular and deeper than normal - Pupils react to light - Swallowing, retching, and vomiting reflexes disappear and reappear in that order - Respiratory response to skin incision decreased - Decreased muscle tone - **Surgical Anesthesia: Stage 3 Plane 2** - Starts when the eyeballs become concentrically fixed - Regular respirations with decreased tidal volume - Respiratory response to skin incision disappears - Moderate loss of muscle tone - Reflex closure of vocal cords begins to disappear - Pupils unreliable - **Surgical Anesthesia: Stage 3 Plane 3:** - Begins with decrease in intercostal muscle activity - Ends with intercostal activity absent and respirations is completely diaphragmatic - Diaphragmatic breathing \> jerking movement - Pupils continue to dilate - **Surgical Anesthesia: Stage 3 Plane 4** - Begins with complete loss of intercostal activity - Ends with loss of spontaneous respiration - Pupils completely dilated - Nonresponsive to light - All muscle tone lost - **Surgical Anesthesia: Stage 3 Plane 5** - AKA respiratory paralysis - AKA too deep - Cessation of respiration due to concentration of anesthetic agent - Ends with circulatory collapse - Anesthesia should be lightened immediately - Emergence - Is a transition process where a patient goes from general anesthesia to awake and spontaneously breathing. - Critical period of recovery from general anesthesia with the return of: - Consciousness - Neuromuscular condition - Airway protective reflexes - A plan of emergence should be developed based on patient's comorbidities and surgeon's needs. - Make sure all 3 critical return are back to normal before extubation - Preparation - Estimate remaining duration of surgical procedure - Decrease anesthetic depth - Administer Reversal - Adequate recovery from neuromuscular blocking agents should be established prior to extubation - Do not readminister muscle relaxants - Awareness - Do not reverse your paralytic while the patient's deep fascia is still open. Patient's intestines will come out of the abdomen. - Pain management - Opioids - Requirements based on: patient's weight, procedure, physiological status, and opioid tolerance. - Respiratory rate can be a useful indicator of adequate analgesia - Administer 100% oxygen for 5-10 minutes - Diffusion hypoxia - Occurs when N20 has been used - Diffuses rapidly from blood into alveoli - Suction - Administer medication to prevention PONV - Titrate analgesia based on patient's respiratory rate - Diffusion hypoxia happens after the nitrous is turned off so patient needs to be taken off nitrous and put on oxygen NOT room air - Address pain before the patient wakes up - Emergence: - Evaluation of signs and stages of anesthesia during emergence - Stage 1: - Extubation performed once stage 1 is reached - Awake extubation - Stage 2: excitement (DO NOT EXTUBATE IN THIS STAGE) - Irregular breathing/breath holding - Possible agitation - Laryngospasm and regurgitation - Stage 3: - Deep extubation - Reverse staging order - Deep extubation performed when the patient is in stage III. They have to be reversed and have to be breathing on their own to be extubated. They do not need to be awake. - If you pull the tube during stage II, they patient will have a laryngospasm. Do not pull the tube in stage II. Look at their pupils and respiratory pattern. If respiratory pattern is not regular, they are still in stage II. If they have breath holding or breathing followed by periods of apnea they are still in stage II. Throw a suction down and see if the patient breath holds. If they hold their breath, they are still in stage II. - Stage I is awake extubation - Deep vs. Awake Extubation - Awake - Trachea is extubated only when the patient responds to simple commands and is breathing spontaneously - Awake Extubation Criteria - Patient conscious and responding to simple commands. - Open your eyes - Squeeze my hand - In full stomach or high risk for aspiration or if difficult intubation extubate only when patient is fully awake - Patient hemodynamically stable, normothermic, not having received massive amounts of fluid - Adequate spontaneous ventilation with tidal volumes \>8ml/kg (per Mrs. Crochet 8ml/kg is ambitious so \>6ml/kg is sufficient). - Adequate reversal of NMB - It is not enough for the patient to be able to lift head off pillow because the smaller muscles of the pharynx may still be affected by NMB. - Deep - Chosen when the presence of an ETT is to be avoided during emergence to prevent "bucking" and straining. - What type of surgery warrants a deep extubation? - Certain neuro procedures, hernia repair, carotid endarterectomy, tummy tuck, plastic procedures, reactive airway disease. - If you want to avoid a potential cardiovascular response - Avoid busking, coughing, straining, response to ETT - Avoid bronchospasm in patients at low risk for aspiration of gastric contents - Who not to deep extubate? - A patient who was a difficult intubation - Patient who is a full stomach - RSI patient - Patients that you struggled to ventilate prior to intubation - Obesity - Risk of regurgitation and/or aspiration of gastric contents is a concern - Monitored Anesthesia Care (MAC) - MAC does not describe the continuum of depth of sedation, rather it describes "a specific anesthesia service in which an anesthesiologist has been requested to participate in the care of a patient undergoing a diagnostic or therapeutic procedure". - If the patient loses consciousness and the ability to respond purposefully, the anesthesia care is a general anesthetic, irrespective of whether airway instrumentation is required. - The provider of monitored anesthesia care must be prepared and qualified to convert to general anesthesia when necessary. - May require varying levels of sedation, analgesia and anxiolysis - Desirable end points to provide patient comfort, maintain cardiorespiratory stability, improve operating conditions and prevent recall of unpleasant perioperative events. - Ideally patient should be able to communicate during procedure - Therapy should be administered to treat pain, anxiety and agitation - Combination Local/MAC - MAC anesthesia= all monitors are on - MAC requires education to your patient about what they can expect - Do not make promises about hearing or feeling things. Especially in MAC and regional anesthetics. - During monitored anesthesia care the anesthesia provider performs a number of services: - Diagnosis and treatment of clinical problems that occur during the procedure - Support of vital functions - Administration of sedatives, analgesics, hypnotics, anesthetic agents, or other medications as necessary for patient safety - Psychological support and physical comfort - Provision of other medical services as needed to complete the procedure safely - Local anesthetic - Which drug - Characteristics/knowledge - Recommended dose - Max dose - Concentration (know how to figure this out) - With/without preservatives - Local anesthetics have max doses. They can have cumulative effects so you need to know what is being given between the surgeon and the anesthesia provider. - Who is not a good candidate? - Children - Confused - Uncooperative - Unable to follow commands - Patients with tremors/ RLS - Patients unable to lie down flat - "An analysis of the ASA closed claims project database focusing on MAC likewise revealed that oversedation and respiratory collapse most frequently lead to claims". - Extra advice: - Be vigilant have airway equipment present. Do not perform MAC without proper equipment. Be prepared to convert to general if needed. - Minimal Sedation (Anxiolysis) - Is a drug induced state during which patients respond normally to verbal commands. Although cognitive function and physical coordination may be impaired, airway reflexes, and ventilatory and cardiovascular functions are unaffected. - Moderate Sedation/ Analgesia (Conscious Sedation) - Is a drug induced depression of consciousness during which patients respond purposefully to verbal commands, either alone or accompanied by light tactile stimulation. No interventions are required to maintain a patent airway, and spontaneous ventilation is adequate. Cardiovascular function is usually maintained. - Reflex withdrawn from a painful stimulus is **NOT** considered a purposeful response - Deep Sedation/Analgesia - Is a drug induced depression of consciousness during which patients cannot be easily aroused but respond purposefully following repeated or painful stimulation. The ability to independently maintain ventilatory function may be impaired. Patients may require assistance in maintaining a patent airway, and spontaneous ventilation may be inadequate. Cardiovascular function is usually maintained. Principles of Anesthesia Week 1 Notes From Handouts **American Society of Anesthesiologists** **Continuum of Depth of Sedation:** **Definition of General Anesthesia and Levels of Sedation/ Analgesia** - Minimal Sedation Anxiolysis - Responsiveness- Normal response to verbal stimulation - Airway- Unaffected - Spontaneous Ventilation- Unaffected - Cardiovascular Function- Unaffected - Moderate Sedation/ Analgesia - Responsiveness- Purposeful response to verbal/ tactile stimuli - Airway- No intervention required - Spontaneous Ventilation- Adequate - Cardiovascular Function- Usually maintained - Deep Sedation/ Analgesia - Responsiveness- Purposeful response following repeated or painful stimuli - Airway- may need intervention - Spontaneous Ventilation- may be inadequate - Cardiovascular Function- Usually maintained - General Anesthesia - Responsiveness- Unarousable - Airway- Intervention often required - Spontaneous Ventilation- Frequently inadequate - Cardiovascular Function- May be impaired **Introduction to Anesthesia The Principles of Safe Practice** -