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Stages of anesthesia
1: analgesia
2: excitement
3: surgical
4: RS & CVS failure
1: regular small TV respiration,
2: irregular respiratory, dilated pupils, absent Eyelash
3:
- phase 1: regular large Tv, pinpoint pupils, absent Eyelid and absent pharyngeal & vomiting reflex
- phase 2: corneal reflex absent
- phase 3: diphramtic respiration and absent larengeal reflex
- phase 4: irregular respiration and absent cranial reflex
4: apnea & widely dilated pupils
Indications for inhalational anesthesia
- Pediatrics
- No accessible veins
- Upper airway obstruction (epiglottis)
- Bronchopulmonary fistula/empyema
- Lower airway obstruction with FB
For 3, 4& 5: to preserve spontaneous ventilation (3), avoid PPV to not displace FB (5)or creat pneumothorax(4)
Complication with inhalational induction
- Slower induction
- Stage 2 problems (laryngospasm, bronchospasm, hiccups).
- Environmental pollution
- Lose of pre-oxygenation advantage
Advantage of TIV and disadvantages
- Avoids complications of inhalational induction (laryngospasm, bronchospasm, and distention of gas filled spaces, diffusion hypoxia, fluoride production).
- safe in MH
- reduces PONV
Disadvantage is plasma concentration not measured and variable in each patient.
Airway assessment: A) oropharyngeal space B) Atlanto-occipital extension/C-spine mobility C) body habits D) others
1) malllampati
- I: soft palate>uvula>fauces>tonsillar
- II: no tonsillar
- III: no fauces
- IV: no soft palate
2) interincisor space normal 3-4.5 cm
3) maxillary prominence “upper lip bite test” correlates with glottic visualization
I: can bite above vermilion
II: can’t reach vermilion
III: can’t bite upper lip (associated with difficult airway)
4) thyromental distance (normal 3 fingers =6-7 cm)
5) sternomental distance (normal 12.5-13.5 cm)
B) < 80 degree ROM predictions of difficult airway
C) BMI > 30 predicts difficult airway & neck circumference > 17 cm
D) beard, edentulous, female, age < 8yrs, displaced airway, overlying neck malformation
Advantage and disadvantages of LMA
Easy to place, HD stability, avoids risk of ETT (bronchospasm, coughing on emergence, airway trauma, sore throat)
Smaller seal leads to ineffective ventilation, no protection against laryngospasm and aspiration. Nerve damage to oropharyngeal (overinflaring cuff with small size), sore throat if used large size.
LMA vs ETT cuff pressure target
LMA 40-60 cm H2O
ETT <25 cm H2O
PPV with LMA < 18- 20 cm H2O
Ideal sniffing position is
80 degrees of Atlantic-occipital angle
+
35 degrees of lower C-spine flextion
BURP maneuver
Backward, Upward, Rightward, Pressure (BURP)
It’s external laryngeal manipulation on thyroid cartilage to improve laryngeal view (not called cricoid pressure)
C/I for light style intubation
Neoplasm of the airway
Airway trauma
C/I for retrograde intubation and complications
Can’t intubate/can’t ventilate (because it takes time to do it)
Anatomical abnormalities (goiter, cancer)
Tracheal stenosis
Coagulopathy
Local infection
C/b
- Bleeding
- Subcetenous emphysema
- Pnumomediastinum
- Pneumothorax
- Post trachea or esophagus injuries
Contraindicated for cricothyrotomy
Laryngeal fx Laryngeal cancer Subglottic stenosis Coagulopathy Unidentifiable neck anatomy
Peds-> should be needle cricothyrotomy never use scaple (surgical cricothyrotomy) because portion of airway and thyroid gland reaches cricothyroid membrane
C/I to percetaneous jet ventilation
Damage to cricoid cartilage or larynx
Complete upper airway obstruction
Relative:
COPD
Coagulopathy
Distorted airway
C/b
- Barotrauma from use high pressure (min pressure < 15 psi should be used and allow sufficient expiration time)
- SC or midistanial emphysema
- Aspiration
- Trechea/esophagus perforation
- Bleeding
Indications for awake intubation
- Difficult mask ventilation and intubation
- Sever aspiration risk
- Facial or airway trauma
- Sever HD instability
- Cervical spine pathology
Airway nerve blocks for intubation
Glossopharyngeal
- innervates: lost&lateraled pharyngeal wall, 1/3 post tongue, vallecula, ant epiglottis
- not done because risk of pharyngeal hematoma and risk injecting into carotid artery.
Sup laryngeal
- lower pharynx, upper larynx, glottic, aryepiglottic
- needle inserted anterio thyrohyoid ligament (walked off Cornu of hyoid bone)
Trans laryngeal
- trachea and vocal cord
Why correct ETT size matter
Because larger tubes cause laryngeal & tracheal mucosal trauma and sore thoat where smaller tubes increases resistance of airway and wob
A 33-year-old woman has been given general anesthesia with inhalational route by desflurane. The anesthesiologist checked the depth of anesthesia by eye examination, He noticed the pupil is partly dilated and the eyeball is roving. The eyelash reflex is absent while eyelid reflex is present. She is in which stage of anesthesia?
A. Stage of analgesia
B. Stage of excitement
C. Stage of surgical anesthesia
D. Stage of impending respiratory and circulatory failure
Guedel described four stages of ether anesthesia dividing the 3rd stage into 4 planes.
Stage 1 is the stage of analgesia, it extends from beginning of anesthesia inhalation to the loss of consciousness.
Stage 2 is stage of excitement, it extends from the loss of consciousness to beginning of regular respiration. There is eyeball roving, partially dilated pupil and loss of eyelash reflex in this stage.
Stage 3 is stage of surgical anesthesia, it extends from beginning of regular respiration to cessation of spontaneous breathing. This stage is further divided into 4 planes.
Plane 1 is from beginning of regular respiration to cessation of eye movement.
Plane 2 is from cessation of eye movement to respiratory paresis.
Plane 3 is from respiratory paresis to respiratory paralysis.
Plane 4 is characterized by intercostal paresis.
Stage 4 is stage of medullary paralysis. There is respiratory arrest and apnea while pupil is fully dilated and fixed. Thus, This patient is in the stage 2, stage of excitement.
A 4-year-old boy is planned to undergo laparoscopic gastrostomy tube placement. He is induced with general anesthesia and intubated with a 4.5 mm cuffed endotracheal tube. The tube is taped 14 cm at the gumline, and the boy is placed on volume control ventilation. Which of the given is the most likely first sight of right mainstem intubation? A. Increased peak inspiratory pressure B. Arterial desaturation C. Hypercapnia D. Hypotension
The correct option is increased peak inspiratory pressure. When migration of an endotracheal tube from an intratracheal position to an endobronchial position occurs, during volume-control ventilation, the first sign of migration is generally an increase in peak inspiratory pressure. Peak inspiratory pressure is a result of the resistance to air in the large airways and the static compliance of the lungs. An endobronchial tube would result in greater resistance being experienced by air flow than in an endotracheal tube.
Arterial desaturation is incorrect as the non-ventilated lung has some reserve of oxygen, which would delay the onset of hypoxemia briefly. Hypercapnia is incorrect as that would develop later on in the patient. Hypotension is incorrect as that would result if the right lung is allowed to hyperinflate, resulting in reduced venous return.
Opioid effect on sleep postoperatively ??
Opioids impair the duration of rapid eye movement (REM) sleep when given during anesthesia. Most anesthetics can lead to an impairment of sleep architecture, such as REM depression and reduced sleep quality during the postoperative period. Opioids have also been found to impair sleep quality and the duration of REM sleep when given during anesthesia. These effects of opioids may be mediated in part by a reduction in the GABAergic transmission in the oral part of the pontine reticular nucleus.
Anesthesia and painful surgical procedures may affect sleep and circadian rhythms for as long as six months, depending on the complexity of the procedure performed. A substantial decrease in REM sleep occurs on the first night after surgery and anesthesia.
This is followed by the REM rebound phenomenon, which is characterized by the lengthening and increasing frequency and depth of rapid eye movement sleep. This phenomenon occurs on the second to fourth postoperative night.
A 19-year-old man presents for right knee arthroscopy and requests spinal anesthesia so that he can watch the procedure on one of the arthroscopy screens. Fifteen minutes after uneventful placement of a bupivacaine spinal, the patient experienced sudden onset of severe hypotension and profound bradycardia, necessitating administration of vasopressors and atropine, and a brief course of cardiac compressions to restore circulation. Which of the following cardiac reflexes is most likely responsible for this event? A. The Carotid Sinus Reflex B. The Chemoreceptor Reflex C. The Bezold-Jarisch Reflex D. The Bainbridge Reflex
The Bezold-Jarish reflex is a paradoxical circulatory response in which cardiovascular depression occurs, with simultaneous relative parasympathetic nervous system activation and sympathetic nervous system depression leading to hypotension and bradycardia. Triggers for the Bezold-Jarish reflex can include reduced cardiac venous return, as in supine inferior vena cava compression during pregnancy, pain and/or fear, myocardial ischemia or infarction, thrombolysis, and during regional anesthesia. It is one of the main proposed mechanism for the bradycardia and hypotension seen during “high spinal” anesthesia. The reflex is believed to be initiated by stimulation of chemo and mechanoreceptors within the left ventricular wall, which then communicate via vagal afferent C fibers to increase parasympathetic tone.
The Carotid Sinus Reflex (or baroreceptor reflex) is responsible for maintaining stable arterial blood pressure. It is mediated by receptors in the carotid sinus and aortic arch, the vagus nerve, the nucleus solitaries in the medulla, and the sympathetic nervous system. Hypotension leads to increased heart rate and contractility, and hypertension causes cardiac depression and slowing of heart rate.
In the Chemoreceptor Reflex, cells in the carotid and aortic bodies respond to changes in blood pH and oxygen tension and signal via a branch of the glossopharyngeal nerve and 10th cranial nerve to the medulla, which then increases ventilator drive.
The Bainbridge Reflex is mediate by stretch receptors in the right atrial wall that signal via the vagus nerve when right-sided cardiac filling pressures rise to decrease parasympathetic tone and increase heart rate. (e.g immediate autotransfusion after delivery from blood returning to heart that is coming from the uterus)
A 19-year-old man with a complex history of Crohn’s disease has undergone several operations for bowel obstruction and again presents for an exploratory laparotomy for suspected small bowel obstruction. He has an NG tube in place, distended abdomen, and appears in severe distress. He has been an easy intubation in earlier cases per the electronic medical record. A rapid sequence induction is planned with cricoid pressure. Aspiration can be completely prevented with which of the following?
A. Withdraw the NG tube prior to induction
B. Hold adequate cricoid pressure
C. Suction the NG tube
D. It may still occur
E. Keep the patient’s head up
Option A is incorrect because withdrawing the NG tube, though it may make it easier to mask ventilate (in case of a failed intubation), does not assure that the stomach has actually been emptied.
Option B is incorrect because cricoid pressure has not been shown in CT and MRI studies to actually close the esophagus.
Option C is incorrect because the NG tube may suction out the liquid, but anything larger than the small holes at the end of the NG tube may remain in the stomach.
Option D is correct for the simple reason that NOTHING has been proven to completely prevent aspiration when intubating a patient with a full stomach.
Option E is incorrect because if the patient vomits during induction, it is better to have the head down to prevent aspirate from going down the trachea.
A 75-year-old man with endobronchial cancer is going for a endobronchial ultrasound. The patient states that he cannot lie flat and feels short of breath at rest. The surgeon asks if the patient might benefit from using heliox for the case. You respond?
A. No, patient likely has a laminar flow obstruction and helium mixed with oxygen would not be helpful
B. No, 100% oxygen would be better than heliox since he is short of breath
C. Yes, heliox would be beneficial as it can improve airflow due to its lower density
D. Yes, the reynolds number for the patient’s airways is estimated to be less than 2300
In the bronchial tree, airflow is usually turbulent; as it reaches the smaller airways and alveoli it usually becomes laminar. In the thorpe tubes, at high flows the gas is turbulent; at lower flows the gas flows in a laminar fashion. In this patient the endobronchial mass is likely creating more turbulent flow and friction making it difficult to breathe. Heliox is a mixture of 79% helium with 21% oxygen. It has a density that is much lower than pure oxygen alone. In turbulent flow the density of the gas is the main driver of resistance. Therefore, the use a gas with lower density would lower the resistance in the airway and allow for better ventilation. In laminar flow the viscosity of the gas is the main determinant of resistance.
A and B are incorrect because heliox would, in fact, be helpful due to reasons stated above
D is incorrect because the patient is likely experiencing turbulent flow, not laminar. The Reynolds number is < 2300 in laminar flow and >4000 in turbulent flow. The Reynolds number is calculated by multiplying velocity x density x length of tube / viscosity.
A 19-year-old man received succinylcholine for intubation during general anesthesia induction for arthroscopic repair of R knee medial meniscus tear. However, at the end of surgery, spontaneous ventilation does not return and neuromuscular monitoring reveals that there is no twitch. Three hours after the end of surgery, motor function returns and he begins to breathe spontaneously and he is extubated without further problems. Testing later most likely reveals which of the following:
A. Succinylcholine hydrolysis has been reduced, and therefore its action prolonged, by reduced hepatic synthesis of butyrylcholinesterase, the primary enzyme responsible for breakdown of succinylcholine.
B. Succinylcholine hydrolysis has been reduced because the patient is heterozygous for a genetic variant of butyrlcholinesterase, greatly prolonging the action of succinylcholine
C. The patient’s Dibucaine number is 60
D. The patient’s Dibucaine number is 25
The action of succinylcholine is terminated by hydrolysis by butyrylcholinesterase, an enzyme synthesized by the liver. Renal function has no direct effect on succinylcholine. Severe liver disease can reduce the synthesis of butyrylcholinesterase by up to 20%, but this is sufficient only to prolong the action of succinylcholine from an average of about 3 minutes, to 9 minutes. Severe prolongation of the action of succinylcholine occurs in the presence of an abnormal genetic variant of butyrylcholinesterase. In individuals who are heterozygous for the abnormal gene, the action of succinylcholine is prolonged 50-100%, and in individuals who are homozygous, the action is prolonged 4 to 8 hours.
The dibucaine number refers to a test with the local anesthetic dibucaine, which inhibits normal butyrylcholinesterase more than the abnormal butyrylcholinesterase. The dibucaine number indicates the percentage of inhibition: the normal enzyme is inhibited 70 to 90% (dibucaine number = 70 to 90). The dibucaine number for heterozygous individuals is 30 to 70, and the dibucaine number for homozygotes is about 30. The severe prolongation of the action of succinylcholine in this patient suggests he is homozygous for a b butyrylcholinesterase variant and his dibucaine number will be < 30.
A 45-year-old man presents for emergency surgery. The patient's weight is 200-kg and height is 5'6". His airway exam is reassuring with a recent history of easy intubation. Which of the given is the most appropriate succinylcholine dose for induction of this patient? A. 60 mg B. 75 mg C. 100 mg D. 200 mg
The correct option is 200 mg. Succinylcholine is used to result in short-term paralysis as part of general anesthesia. This helps with tracheal intubation or electroconvulsive therapy. It is usually given IV or IM. Also, it is currently the only drug used in anesthesia, where the induction dose is based on total body weight. The dose of the drug is 1 mg/kg since this is a 200-kg patient; 200 mg should be used.
An Anesthetist performed airway assessment for a 22-year-old man. After examination, he concluded that the patient is in class I of upper lip bite test (ULBT). What does the class I ULBT mean?
A. Intubation is extremely difficult
B. Lower incisors can bite above the vermillion border of upper lip
C. Lower incisors cannot reach vermilion border
D. Lower incisors cannot bite upper lip
The extent of an individuals’ ability to prognath the mandible is an important correlation of visualization of glottic structures during direct laryngoscopy.
The Upper Lip Bite Test(ULBT) is used to assess the ability of patient to prognath the mandible. The Upper Lip Bite Test classification system is as follows.
Class I: Lower incisors can bite above the vermilion border of the upper lip
Class II: Lower incisors cannot reach vermilion border of upper lip
Class III: Lower incisors cannot bite upper lip Class III is associated with a difficult intubation. Class I is associated with relatively normal intubation.
However other conditions like Ludwig’s angina, tumor or masses, scarring due to radiation, previous neck surgery etc can also decrease submandibular compliance and can result in difficult intubation.
A 29-year-old G1P0 parturient with myasthenia gravis (MG) presents at 37 weeks with preeclampsia, complaining of severe headache and blind spots in her vision. Her blood pressure on admission is 173/115 mmHg. Early in the pregnancy, the patient was hospitalized and intubated for a respiratory crisis. Which one of the following plans represents the most appropriate management?
A. Initiation of magnesium sulfate infusion for seizure prophylaxis awaiting surgical delivery at 38 weeks
B. Urgent surgical delivery after the induction of general anesthesia with propofol and rocuronium followed by endotracheal intubation
C. Urgent surgical delivery after epidural placement and slow incremental titration of local anesthetic to achieve a T4-T6 level
D. Immediate surgical delivery after an intrathecal injection of high dose local anesthetic
E. Expectant management in anticipation of spontaneous vaginal delivery to avoid the operative risk of Cesarean section
The anesthetic implications of MG and preeclampsia are both high yield board topics. MG is an autoimmune disorder characterized by muscle weakness and fatigue resulting from destruction of acetylcholine receptors at the neuromuscular junction by autoantibodies. A history of respiratory crisis suggests high severity of the disease, which is often worsened in pregnancy. Because magnesium produces muscle weakness by inhibiting acetylcholine release, it is contraindicated in patients with MG and has been reported to cause death in cases of severe MG. Expectant management is inappropriate given the risk to the patient of progression to eclampsia, especially in the setting of avoiding magnesium prophylaxis.
A neuraxial technique poses less risk to the patient than induction of general endotracheal anesthesia as it avoids the need to intubate a potentially difficult airway and the risk of stroke as a result of laryngoscopy induced hypertension. A slow titration of local anesthetic to achieve a surgical level is preferred to minimize the risk and extent of engendering further respiratory muscle weakness. The practitioner must nevertheless be prepared to escalate to general endotracheal anesthesia to support ventilation in the event of respiratory insufficiency/failure secondary to muscle weakness.
A 52-year-old man presents to the OR urgently for an exploratory laparotomy for suspected bowel ischemia. The emergency department physician’s note details recent cocaine use. Several hours into the procedure, the patient is noted to have marked hypotension, refractory to intravenous fluids. In the patient with recent cocaine use which one of the following statements describes the likely adrenergic response to direct/indirect sympathomimetic drugs?
A. Increased/increased B. Increased/decreased C. Decreased/decreased D. Decreased/increased E. Decreased/no difference
Endogenous catecholamines are cleared from the synaptic cleft primarily by re-uptake into neuronal and non-neuronal tissue. Remaining neurotransmitters are metabolized by degradative enzymes such as monoamine oxidase or catechol O-methyltransferase. Exogenous drugs with molecular structures similar to catecholamines, such as cocaine and tricyclic antidepressants, act as competitive inhibitors of both mechanisms of reuptake and degradation and can significantly alter the typical physiologic response to sympathomimetics.
Cocaine inhibits catecholamine re-uptake. In this setting, administration of a direct-acting sympathomimetic, such as phenylephrine, produces an increased response due to the combined effect of more endogenous catecholamines remaining in the synaptic cleft in addition to the exogenous drug. Conversely, indirect sympathomimetics that depend upon the release of stored endogenous catecholamines will release vesicles with depleted stores of neurotransmitters due to impaired re-uptake and thus have a decreased response.
An anesthesiologist/researcher is studying intraoperative consciousness during general anesthesia using muscle relaxants. His study design consists of placing and inflating a forearm tourniquet above arterial systolic pressure just prior to intravenous injection of propofol to induce general anesthesia and administration of a muscle relaxant. After intubation and transition of the patient to an inhaled anesthetic, at 3 different points during the surgery, the researcher asks the patient to raise the hand on the tourniquet side. Despite appearing anesthetized, the patient raises his arm each time. Postoperatively, the patient has no memory of the operating room after the injection of propofol. Which term(s) most certainly accurately describes what we can definitely say about this patient?
A. He had intraoperative awareness only
B. He had intraoperative awareness, episodic recall and responsiveness
C. He was unconscious
D. He had intraoperative responsiveness only
Terminology regarding memory, consciousness, and responsiveness during “general anesthesia” is often confused in the literature, by anesthesiologists, and by patients. Because various experiences and responses may have very different implications, both for postoperative patient treatment and for development of means to monitor for and prevent adverse patient experiences, it is important to be as precise as possible. General anesthesia is largely the “science of unconsciousness”. Awareness itself is the subjective experience of an individual. Persons who are “unaware” do not have a subjective experience of themselves or their surroundings. . Awareness is uncoupled from recall - a person can be aware, but not remember their experience later. Responsiveness is a measure of whether a person can and does act in response to an experience. Responsiveness is dependent not only on a person’s ability to perceive and experience, but their ability to act-the presence of a muscle relaxant may prevent an awake patient from responding to a verbal or surgical stimulus, even though they are aware of it and have recall of it later. Recall is the ability to remember events after they have happened and is uncoupled from awareness: a person can be aware of an event at the time of its occurrence, but unable to recall it later.
Memory is a complex set of functions-there are multiple memory systems, each of which can be present without the others, and depend upon different functional areas of the brain. Episodic memory is the recollection of events with a clear spatiotemporal context (who, what, when, where). Semantic memory is the recall of facts without spatiotemporal context (i.e. the ability to remember the names of the 7 highest mountain peaks on the globe, even if the person cannot remember where or when they acquired the knowledge). Other memory various memory functions include familiarity (e.g. recognizing a face without being able to contextualize the person), short term memory, and emotional memory. In this case, the patient had a subjective experience that he can recall and describe (he remembers conversation in the operating room) and he was, therefore, aware and not unconscious for at least part of the procedure. In addition, by isolating the forearm with a tourniquet and protecting it from the effects of neuromuscular blockade, the patient was responsive. The patient may additionally have retrograde amnesia for some events: but this is difficult to judge, since we don’t know the total extent of his consciousness and awareness. This patient certainly demonstrates awareness, episodic recall, and responsiveness.
A 1-week old neonate is brought to the OR for repair of an incarcerated hernia. In which one of the following ways does heat loss and heat conservation in the pediatric patient compare to that seen in the adult?
A. Shivering is a more effective heat conservation method for infants
B. Non-shivering thermogenesis is a mechanism of heat production exclusive to infants
C. Compared to adults, children depend less on sweating for heat regulation
D. Compared to infants, the relative increase in heat production by non-shivering thermogenesis is lower for adults
E. Unlike in adults, infants lose more heat from their head than from an equal amount of surface area on the trunk
Brown fat and skeletal muscle, which generate heat through the uncoupling of oxidative phosphorylation, is a major source of non-shivering thermogenesis at all ages, although the relative increase in heat production is higher in infants than adults. Shivering, by contrast, is not an effective method of thermogenesis until after early childhood. In adulthood, however, shivering can increase metabolic heat production by 50% to 100%.
Compared to adults, children depend more on sweating for heat regulation, and are therefore more susceptible to hyperthermia after poisoning with muscarinic antagonists. It is a false perception that, surface areas being equal, heat loss from the head is greater than any other part of the body; heat loss is, in fact, simply proportional to body surface area.
A 50-year-old patient develops stridor and difficulty breathing upon extubation after a complicated total thyroidectomy. The surgical site is seen to be normal. Which of the following is the most likely etiology of the patient’s presentation?
A. Bilateral superior laryngeal nerve injury (external branch)
B. Bilateral superior laryngeal nerve injury (internal branch)
C. Bilateral recurrent laryngeal nerve injury
D. Hematoma
The correct option is bilateral recurrent laryngeal nerve injury. The recurrent laryngeal nerve innervates all the muscles of the larynx except for the cricothyroid. Unilateral damage to this nerve will result in hoarseness, but bilateral damage will result in respiratory distress. Visualization of the vocal cords will show a paramedian position of the cords. Bilateral superior laryngeal nerve injury (external branch) is incorrect as that will only result in hoarseness, whereas unilateral damage will have minimal effect on the voice. Bilateral superior laryngeal nerve injury (internal branch) is incorrect as that will not result in stridor and dyspnea as it must be noted that the internal branch is sensory. Hematoma is incorrect as that results within the first few hours after surgery (generally within 6-24 hours). Also, this patient is not presenting with any signs of a hematoma.
An 18-year-old woman, ASA 2 for chronic sinusitis, presents to the operating room for an endoscopic sinus surgery. After an uneventful intubation, the patient appears to have experienced bronchospasm demonstrated by high peak pressures on the ventilator and difficulty with manually ventilating the patient. This resolves after treatment. Which of the following innervation is responsible for bronchospasm?
A. Vagus nerve B. Glossopharyngeal nerve C. Alpha 1 adrenergic receptors D. Beta 2 adrenergic receptors E. T1-4 Sympathetic activity
Bronchospasm is a protection mechanism of the upper airway to protect the lungs from aspiration. Some triggers include intubation, history of asthma, light anesthesia or extubation.
Option A is the correct answer. The tracheobronchial tree is innervated by the vagus nerve (cranial nerve X) and the vagus mediates bronchoconstriction and increases bronchial secretions. The vagus nerve is responsible for sensation to the airway below the level of the epiglottis. The branches of the vagus nerve are the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). The SLN divides into an external (motor) nerve and internal (sensory) nerve innervating the larynx between the epiglottis and the vocal cords. The RLN innervates the area between the vocal cords and the trachea.
Option B is incorrect as the glossopharyngeal nerve (Cranial nerve IX) innervates the roof of the pharynx, tonsils and undersurface of the soft palate and does not participate in bronchospasm activity.
Option C is incorrect because sympathetic activity T1-4 provides bronchodilation and decreases secretions. (Think fight or flight ? want bronchodilation in order to breathe better in order to fight or escape).
Options D and E are incorrect because although there are alpha 1 and Beta 2 adrenergic receptors in the pulmonary vasculature, they have minimal effect on tone. Alpha 1 causes vasoconstriction and Beta 2 mediates vasodilation.
Which one of the following indicators is the most reliable assessment of adequate reversal of drug-induced neuromuscular blockade on an awake, extubated patient following general endotracheal anesthesia?
A. 5 seconds of sustained tetanus to 100-Hz stimulation
B. Bedside assessment of grip strength
C. 5-second sustained head lift
D. Ability to strongly oppose the incisor teeth against a tongue depressor
E. Ability to lift the legs off the bed
In the anesthetized patient, 5 seconds of sustained tetanus to 100-Hz stimulation is the most reliable indicator of adequate reversal of drug-induced neuromuscular blockade. However, in an awake patient, the application of painful train-of-four or tetanic stimulation is not greeted with a positive patient interaction. Therefore, clinical assessment of reversal of neuromuscular blockade is preferred. This includes grip strength, tongue protrusion, the ability to lift the legs off the bed, and the ability to lift the head off the bed for a full 5 seconds.
Of the clinical assessment maneuvers, the 5-second sustained head lift has been considered by some to be the standard, reflecting not only generalized motor strength but, more importantly, the patient’s ability to maintain and protect the airway. However, the ability to strongly oppose the incisor teeth against a tongue depressor is a more reliable indicator of pharyngeal muscle tone. This maneuver correlates with an average train-of-four ratio of 0.85 as opposed to 0.60 for the sustained head lift.
What’s the mortality rate from solely anesthesia complications?
Perioperative mortality involves multiple factors, including but not limited to patient co-morbidities, surgical complications, and anesthesia complications. Anesthesia mortality can be measured in different ways:
1) perioperative mortality, or the number of deaths following anesthesia within a certain period of time (usually 30 days),
2) anesthesia-related mortality, in which the anesthetic is the sole or partial cause of mortality, and
3) anesthesia sole-cause mortality, in which the anesthetic itself is the cause of death.
Studies of anesthesia-associated deaths can be designed to examine any of these or a combination of them, and specific statistics, therefore, can sometimes appear to be conflicting. Several things are known, however. Many studies have demonstrated that over time, anesthesia associated mortality has fallen. Between 1960 and 1984, for example, one study demonstrated that the rate of anesthesia-attributable deaths fell from 1 in 5500 to 1 in 26,000; and the rate of anesthesia-attributable death is believed to be significantly lower today than in 1984. Prospective studies of complications associated with anesthesia in France demonstrated that pulmonary complications, and postoperative respiratory depression in particular, were responsible for the largest number of post-anesthesia deaths, followed by cardiovascular events. A British study of 1 million anesthetics found that the anesthetic was the sole cause of death in 1 out of 185,000 surgeries. Both increasing age and ASA status are associated with increased mortality; one study shows that the rate of anesthesia-related deaths for ASA 3 patients is 1 to 2 per 10,000 surgical cases. One approach to this that usually sets patients’ minds at ease is to say “the most dangerous part of the operation is the drive to the hospital”.
SOURCE: Holland R. Anaesthetic mortality in New South Wales. Br J Anaesth 1987; 59:834-41. Tiret L, Desmonts JM Hatton F, Vourc’h G. Complications associated with anaesthesia-a prospective survey in France. Can Anaesth Soc J. 1986; 33(3 Pt 1):336-44.
60-year-old woman is undergoing D & C (dilation and curettage) for uterine bleeding. She suffers additionally from severe gastroesophageal reflux but is otherwise completely healthy. She did not tolerate an office procedure and fears spinal anesthesia, so it is determined that she should undergo brief general anesthesia with endotracheal intubation for airway protection during this procedure. What are the American Society of Anesthesiologists’ standards with regard to ventilator monitoring for this case?
A. The presence of expired carbon dioxide must be continuously documented, unless invalidated by the patient, procedure or equipment
B. Quantitative capnography, capnometry or mass spectroscopy must be used to provide continual carbon dioxide analysis from the time of intubation to extubation
C. A breathing system disconnect detection device must be present if a ventilator is in use and must have continuous visible display if the audible alarms are turned off
D. It is sufficient to continually monitor the patient’s adequacy of ventilation via clinical signs such as chest excursion, observation of the reservoir breathing bag and auscultation of breath sounds
In interpreting monitoring standards, it is important first of all to appreciate the difference between “continual” (happening at frequent intervals) versus “continuous” (happening without interruption). The ASA committees are careful to use these terms explicitly in guidelines and standards statements. An arterial line, for example, provides continuous monitoring of blood pressure, whereas a blood pressure cuff provides continual monitoring. In the case of ventilator monitoring, the ASA Standard requires continual and not continuous monitoring of the adequacy of ventilation throughout a general anesthetic. If the patient is under general anesthesia via mask, the ASA Standard requires continual clinical assessment via chest excursion, observation of the reservoir breathing bag and/or auscultation of breath sounds. However, during cases utilizing a laryngeal mask airway (LMA) or tracheal intubation, the standard is raised to require in addition continual end-tidal carbon dioxide analysis form the time of LMA placement or endotracheal intubation, until extubation or removal of the LMA. It is never sufficient to have respiratory and/or ventilator and breathing circuit audible alarms turned off, and the ASA Standard explicitly requires that the be at all-time audible to the anesthesia care team.
A healthy patient is under general anesthesia with an endotracheal tube. Which of the following methods is most commonly employed to detect CO 2 in patients under general anesthesia?
A. IR absorption B. Mass spectrometry C. Polarographic analysis (Clark electrode) D. Paramagnetic analysis E. Colorimetric analysis
Answer A is correct because IR absorption is the most commonly utilized form of CO2 monitoring. It is straightforward, reliable and relatively inexpensive compared to other choices. Mass spec is older technology used for inhaled gases. C and D are used for oxygen. E can be used for CO2 but it does not quantify it.
Correct placement of LMA is
If situated correctly, the LMA distal tip rests over the upper esophageal sphincter, the wide cuff base rests against the base of the tongue and the lateral cuff walls rest over the pyriform fossae.
healthy 18-year-old patient undergoes monitored anesthesia care for a hernia repair. Which level of anesthesia is best represented by the following statements from the ASA practice guidelines for sedation: purposeful response to mild tactile or verbal stimulation, no airway intervention required, adequate spontaneous ventilation, and cardiovascular status typically maintained?
A. No sedation B. Minimal sedation C. Moderate sedation D. Deep sedation E. General anesthesia
C. Moderate sedation
Explanation:
The ASA practice guidelines describe 4 levels of sedation: minimal sedation, moderate sedation, deep sedation, and general anesthesia. These levels of sedation are on a continuum, whereby patients can easily progress to a deeper level of anesthesia than intended. It is thus important to have continuous patient monitoring when administering sedation and be prepared if the patient enters into a deeper level of anesthesia than anticipated. The statements listed above represent a patient under moderate sedation.
As defined by the ASA, minimal sedation is a patient who has normal response to verbal stimulation with unaffected airway, ventilation, and cardiovascular function.
Deep sedation is defined as purposeful response following repeated or painful stimulation with possible airway intervention required, possible inadequate ventilation, but typically maintained cardiovascular function.
General anesthesia is defined as a patient who is unarousable with airway intervention often required, frequently inadequate spontaneous ventilation, and possible impairment of cardiovascular function.
Why ETT cuff pressure kept below 25
The correct option 25-30 mmHg. Instances where patients are intubated with cuffed endotracheal tubes, tracheal capillary arteriolar pressure has to be kept in mind. If the endotracheal cuff exerts a pressure greater than the capillary arteriolar pressure, tissue ischemia may result. Tracheal ring destruction and tracheomalacia will result due to persistent ischemia. Endotracheal tubes with low-pressure cuffs are indicated in patients who are to be intubated for greater than 48 hours as this reduces the chances of development of tissue ischemia.
ASA Class
The current ASA risk classification system is an attempt to classify the risk associated with anesthesia and surgery. It is intended to give a subjective risk based on the patient's preoperative medical history. The type of procedure is not considered in the classification scheme. ASA III patients have significant or severe systemic disease limiting normal activity, such as renal failure on dialysis or class 2 congestive heart failure. This systemic disease poses a significant impact on daily activity. ASA I is a healthy patient without biochemical or psychiatric disease. ASA II is a patient with mild systemic disease, such as mild asthma or well-controlled DM. This disease state does not pose an impact on daily activity. ASA IV describes a severe disease that is a constant threat to life or requires intensive therapy such as an intervention for an acute myocardial infarction. Such a disease state has a major impact on anesthesia and surgery. ASA V is a patient who is equally likely to die in the next 24 hours with or without surgery.
What weight you consider not using LMA and intubate instead
The LMA classic has an oval-shaped silicon mask with cuff that sit in laryngopharynx and help to make a seal around periglottic tissue. It contents airway tube which has a standard 15 mm diameter which is attached to anesthesia circuit or to bag valve device. The seal around the laryngeal inlet allows for delivery of oxygen and inhaled agent which permits PPV up to 20 cmH20.
In this case patient is adult with age above 100 kg so size 6 SGA should be used. Once a patient starts going above 100 kg, prudence would dictate you intubate this patient since they are an aspiration risk.
What nerve mediates bronchospasm
The tracheobronchial tree is innervated by the vagus nerve (cranial nerve X) and the vagus mediates bronchoconstriction and increases bronchial secretions. The vagus nerve is responsible for sensation to the airway below the level of the epiglottis. The branches of the vagus nerve are the superior laryngeal nerve (SLN) and the recurrent laryngeal nerve (RLN). The SLN divides into an external (motor) nerve and internal (sensory) nerve innervating the larynx between the epiglottis and the vocal cords. The RLN innervates the area between the vocal cords and the trachea.
although there are alpha 1 and Beta 2 adrenergic receptors in the pulmonary vasculature, they have minimal effect on tone. Alpha 1 causes vasoconstriction and Beta 2 mediates vasodilation.
Factors influencing MAC
Several physiological and pathological factors can bring about a variation in MAC of an inhalational anesthetic drug. Hyperthermia (option B) is the correct answer as an increase in the body temperature increases the requirement of an anesthetic drug. Other options are incorrect as they all act to lower MAC. Factors that increase MAC include fever, hyperthermia, stimulants acting on central nervous system (CNS), chronic alcoholism, cocaine use, and hypernatremia. Some studies also show that color of hair can influence MAC and having red hair increases MAC. Infants are also known to have higher anesthetic requirements (highest at the age of 6 months).
Factors that decrease MAC include hypothermia, hyponatremia, CNS depressants, sedatives, PaCO2 > 90 mmHg, PaO2 <40 mmHg, pregnancy, acute alcohol abuse and advancing age. Studies show that there is a 6% decrease in MAC with every additional decade of life.
Factors having little or no effect on MAC include duration of anesthesia, gender, height, and weight of the patient.
A 65-year-old male is undergoing open-heart surgery and the surgeon requests a dose of heparin. Which one of the following is a side effect of heparin when administered during cardiopulmonary bypass surgeries?
A. Thrombocytosis B. Increased SVR C. Hypothermia D. Increased pulmonary vascular resistance E. Decreased antithrombin activity
Heparin resistance, an inability to achieve therapeutic anticoagulation, has been described in as many as 22% of patients undergoing open-heart surgeries. Paradoxically, patients who receive intermittent or continuous therapy with heparin manifest a progressive reduction of antithrombin activity to values that are approximately one-third of normal. Thus, a heparin-induced decrease in the activity of antithrombin may paradoxically increase the thrombotic tendency in humans.
Thrombocytopenia due to heparin administration can be divided into 2 syndromes. The most common syndrome is mild, occurring in 30% to 40% of heparin-treated patients manifesting as platelet counts of less than 100,000 cells/mm3. This mild thrombocytopenia is attributed to drug-induced platelet aggregation. It typically manifests between 3 to 15 days after initiation of therapy (median 10 days) but has been reported to begin within hours in patients previously exposed to heparin. The platelet count usually returns to baseline within 4 days after heparin is discontinued. A second, more severe and even life-threatening syndrome develops in 0.5% to 6% of patients, manifesting as severe thrombocytopenia (50,000 cells/mm3), often with associated resistance to the effects of heparin and the occurrence of thrombotic events.
This severe response typically develops after 6 to 10 days of heparin therapy and is probably due to the formation of heparin-dependent antiplatelet antibodies that trigger platelet aggregation, resulting in thrombocytopenia. Heparin is obtained from animal tissues; thus, caution should be used in its administration to a patient with a preexisting history of allergies. Indeed, fever, urticaria, and even cardiopulmonary changes occasionally occur after administration of heparin.
Rapid IV infusion of large doses of heparin (300 U/kg) as administered before cardiopulmonary bypass may cause modest decreases in mean arterial pressure and pulmonary artery pressure. These changes principally reflect decreases in systemic vascular resistance, perhaps due to a direct heparin-induced relaxant effect on vascular smooth muscles.
Oculocardiac reflex
The correct answer is trigeminal and vagus nerves. The reflex involved in the described patient is the oculocardiac reflex. It consists of vagally-mediated bradycardia and hypotension with pressure on eye globe. The afferent limb of oculocardiac reflex is the ophthalmic branch of trigeminal nerve which transmits the impulses through the gasserian ganglion to the main trigeminal sensory nucleus. The efferent limb is the vagus nerve that inhibits the sinoatrial node at the left atrium leading to bradycardia.
The oculocardiac reflex is triggered by any stimulus that causes direct pressure on the eye globe, traction to the extraocular muscles, ocular manipulation, and ocular pain. It is also activated in cases of orbital bone fracture or orbital tumors. The reflex is more pronounced in children and young healthy adults, and it tends to wane with age. Therefore, it is commonly encountered with pediatric anesthesiologists during strabismus surgery as the case mentioned in this question.
