Anaesthetics Flashcards
What are the two types of anaesthesia?
General anaesthesia – making the patient unconscious
Regional anaesthesia – blocking feeling to an isolated area of the body (e.g., a limb)
What is malignant hyperthermia?
A severe reaction to certain drugs used for anesthesia.
Symptoms -
Increased body temperature (hyperthermia)
Increased carbon dioxide production
Tachycardia
Muscle rigidity
Acidosis
Hyperkalaemia
What is the treatment of malignant hyperthermia?
Dantrolene
What is the triad of general anesthesia and give examples?
Analgesia - Fentanyl
Muscle Relaxants - Rocuronium bromide, Suxamethonium chloride
Hypnosis - Ketamine, Propofol
In an emergency scenario, where detailed pre-planning is not possible, which procedure is used to gain quick and safe control over the airway via intubation?
Rapid Sequence induction
It is also used in non-emergency situations where the airway needs to be secured quickly to avoid aspiration, such as in patients with gastro-oesophageal reflux or pregnancy.
Which common condition can lead to gastrointestinal bleeding in critically unwell patients in ICU?
Stress related mucosal disease
What do inotropes do?
Increase cardiac contractility
What do vasopressors do?
Increase vasoconstriction
What is the APACHE score used for?
To predict mortality at the time of admission to ITU
What is FiO2?
The fraction of inspired O2
This means the concentration of oxygen in the gas that is being inhaled
Where is the anaesthetic agent injected to achieve spinal anaesthesia?
Into the cerebrospinal fluid in the subarachnoid space
Which other term can be used to describe a spinal anaesthesia / spinal block?
Central neuraxial anaesthesia
What type of catheter is a Swan-Ganz catheter?
Pulmonary Artery Catheter
Inserted into the pulmonary artery used to measure pressure in the right atrium
Which inhaled medication is most commonly used to maintain general anaesthesia?
Sevoflurane
Where are the most common sites for insertion of a central venous catheter?
Internal Jugular Vein
Subclavian Vein
Femoral Vein
What are the two main methods for reducing the risk of venous thromboembolism (VTE) in critically unwell patients?
LMWH ( Enoxaparin )
Intermittent Pneumatic Compression devices
Which intravenous medication is most commonly used to induce general anaesthesia?
Propofol
What adverse effect can epidural anaesthesia have on labour and delivery?
Increased second stage ( Second stage describes the period of time from when the cervix is fully dilated to when the baby is born )
Increased likelihood of instrumental delivery ( Forceps / Ventouse )
Which term refers to the amount that the heart muscle is stretched when filled with blood just before a contraction?
Preload
Where is the anaesthetic agent injected to achieve epidural anaesthesia?
Into the epidural space , layer before dura mater
Which term describes anaesthetic agents that are liquid at room temperature and need to be vaporised into a gas to be inhaled? (1)
What device is used for this purpose? (1)
Volatile
Vaporiser
Which medication is used to reverse the effects of opioids in life-threatening overdose?
Naloxone
What does the term cardiac output refer to?
What is the formula for cardiac output?
The volume of blood pumped out by the heart per minute
CO = SV x HR
Which class of drug is typically used as premedication to relax the muscles and reduce anxiety before a general anaesthetic?
Give an example of this class of drug?
Benzodiazepines
Midazolam , Lorazepam
What methods/masks can be used to deliver different concentrations of oxygen without adding or controlling the pressure?
Nasal cannula
Simple face mask
Venturi mask
Non-rebreather mask
What is the Fio2 and maximum flow rate of a nasal cannula?
24 – 30% O2 (maximum flow rate of 4L/min)
Nasal cannulae (NC) are used for mild hypoxia, typically in non-acute situations.
What is the Fio2 and flow rate of a Simple face mask?
The mask delivers 30 – 40% O2 (flow rate 5-10 L/min)
Simple face masks (also called Hudson masks) are typically used to treat mild to moderate hypoxia.
What is the Fio2 and flow rate of a Non-rebreather mask?
This mask delivers approximately 70% O2 when used with a 15L oxygen flow rate.
Used for significant hypoxia. Non-rebreather masks can deliver high FiO2 concentrations as the oxygen is inhaled from both the reservoir bag as well as the direct oxygen source.
How do you fit a non-rebreather mask?
For the mask to work effectively, the reservoir bag needs to be filled before the mask is fitted to the patient. To fill the reservoir bag, obstruct the valve with your finger until the bag is filled with oxygen.
What are Venturi masks used for?
Venturi masks are designed to deliver constant FiO2 regardless of the patient’s respiratory rate and flow pattern (i.e. a fixed-performance device).
They are used to deliver oxygen to patients with chronic obstructive pulmonary disease (COPD) due to the risk of type 2 respiratory failure.
The green venturi mask MUST be on a flow rate of 12-15L to work
Which term describes the situation where pain is experienced with sensory inputs that do not normally cause pain (e.g., light touch)?
Allodynia
What is the first-line medication for managing trigeminal neuralgia?
Carbamazepine
Which term refers to the resistance that the heart must overcome to eject blood from the left ventricle, through the aortic valve and into the aorta?
Afterload
What are the two groups of nerve fibres that transmit pain? (2)
Which of these is myelinated? (1)
Which has a larger diameter? (1)
C Fibres and A-delta fibres
A-fibres and myelinated and have a larger diameter
Which term refers to pain and restriction when opening the jaw?
Trismus
What is the most extreme form of respiratory support, where respiratory failure is not adequately managed by intubation and ventilation?
Extracorporeal Membrane Oxgenation
How is the size of an oropharyngeal (Guedel) airway measured to ensure the correct size for the patient?
From the centre of the mouth to the angle of the jaw
An oropharyngeal airway (also known as an oral airway, OPA or Guedel pattern airway) is a medical device called an airway adjunct used in airway management to maintain or open a patient’s airway. It does this by preventing the tongue from covering the epiglottis, which could prevent the person from breathing.
Which term refers to the resistance in the systemic circulation that the heart must overcome to pump blood around the body?
Systemic Vascular Resistance
What are the two categories of muscle relaxants that may be used during a general anaesthetic? (2)
Give examples of each. (2)
Depolarising - Suxamethonium Chloride
Non-depolarising - Rocuronium Bromide
What is the method of action of Ondansetron?
Which kind of patients should it be avoided in?
5HT3 Receptor Antagonist
Those at risk of a prolonged QT Interval
What type of line is inserted into a peripheral vein and fed through the venous system until the tip is in a central vein (the vena cava)?
Peripherally Inserted Venous Catheter ( PICC Line)
What is the difference between CPAP and non-invasive ventilation (or BiPAP)?
CPAP provides continuous positive pressure through the mask and into the airway, which helps to keep the airway open -> Type 1 Respiratory Failure
BiPAP/NIV provides both high and low pressure to aid inhalation and exhalation ( Ventilation ) -> Type 2 Respiratory Failure
What is the name of the extra hole on the side of the tip of an endotracheal tube that gas can flow through should the main opening become occluded?
Murphy’s Eye
How is the size of a nasopharyngeal airway measured to ensure the correct size for the patient?
From the nostril to the tragus of the ear
When would you use a nasopharyngeal airway instead of a oropharyngeal airway?
In a deeply unresponsive/unconscious patient, an oropharyngeal airway is safe to use because the gag reflex will be depressed. Another advantage of the nasopharyngeal airway is that it can be used in patients with mouth trauma, where an oropharyngeal airway cannot or should not be used.
Give an example of an alpha-2-adrenergic agonist that may be used as premedication before a general anaesthetic to reduce pain?
Clonidine
What is sugammadex used for?
To reverse the effects of nondepolarizing muscle relaxants e.g Rocuronium
How long should patients not have clear fluids before surgery?
2 hours of no clear fluids (fully “nil by mouth”)
Why must patients be NBM during the surgery?
The purpose of fasting is to make sure they have an empty stomach, to reduce the risk of the stomach contents refluxing into the oropharynx (throat), then being aspirated into the trachea (airway). Gastric contents in the lungs creates an aggressive inflammatory response, causing pneumonitis (inflammation of the lung tissue).
It protects the airway
What are the types of airways ?
Laryngeal Mask ( LMA )
Nasopharyngeal airway
Orophayngeal airway
Endotracheal intubation (ETA) - Protection against aspiration and gastric insufflation. More effective ventilation and oxygenation. Facilitation of suctioning.
What does intubation mean?
Inserting a tube into the body
What is preoxygenation?
Before being put under a general anaesthetic, the patient will have a period of several minutes where they breathe 100% oxygen.
This gives them a reserve of oxygen for the period between when they lose consciousness and are successfully intubated and ventilated (in case the anaesthetist has difficulty establishing the airway).
What medications are given prior to surgery to help reduce anxiety and relax the patient?
Benzodiazepines e.g Midazolam
What medications are given prior to surgery to reduce pain and reduce the hypertensive response to the laryngoscope?
Opiates e.g Fentanyl
Why is Rapid Sequence Induction more risky?
Patient has not fasted - increased risk of aspiration
Anaesthetist has not been able to plan for individual problems e.g difficult airway
What is Cricoid Pressure?
Pressing down on the cricoid cartilage to compress the oesophagus and prevent reflux of stomach contents into pharynx.
Which types of medications are commonly used to induce and then to maintain anaesthesia?
Commonly, an intravenous medication will be used as an induction agent (to induce unconsciousness), and inhaled medications will be used to maintain the general anaesthetic during the operation.
Why are I.V medications quicker to induce a patient?
Inhaled medications need to diffuse across the lung tissue and into the blood, where it takes a while for them to reach an effective concentration. IV agents have a head start, as they are infused directly into the blood and so can quickly reach an effective concentration.
What is Total intravenous anaesthesia (TIVA) ?
When both induction and maintenance of anesthesia is done via IV medications.
Usually Propofol
Gives a nicer wake up
How do muscles relaxants work?
Muscle relaxants block the neuromuscular junction from working. Acetylcholine (the neurotransmitter) is released by the axon but is blocked from stimulating a response from the muscle.
What are the common opioids used for the Analgesia part of the triad?
Fentanyl
Alfentanil
Remifentanil
Morphine
What are commonly given post op to reduce N+V?
Ondansetron (5HT3 receptor antagonist) – avoided in patients at risk of prolonged QT interval
Dexamethasone (corticosteroid) – used with caution in diabetic or immunocompromised patients
Cyclizine (histamine (H1) receptor antagonist) – caution with heart failure and elderly patients
What is emergence?
Waking up of the patient
Before waking the patient, the muscle relaxant needs to have worn off. It is not good for the patient to regain consciousness whilst still paralysed (“awareness under anaesthesia”).
What might be used to determine whether the muscle relaxant has work off?
Nerve stimulator , commonly of ulnar nerve watching for thumb movement (twitches)
Can also test facial nerve, stimulated at the temple while watching for movement in the orbiculares oculi muscle at the eye. This involves a train-of-four (TOF) stimulation, where the nerve is stimulated four times to see if the muscle responses remain strong (indicating it has worn off) or whether they get weaker with additional stimulation (indicating it has not fully worn off).
Can be reversed by Neostigmine
Can be reversed by Sugammadex (only non-depolarising muscle relaxants (rocuronium and vecuronium).
When is the patient extubated?
When the muscle relaxant and anaesthesia wears off and they are breathing for themself
What are the risks of anaesthesia?
Accidental awareness (waking during the anaesthetic)
Aspiration
Dental injury, mainly when the laryngoscope is used for intubation
Anaphylaxis
Cardiovascular events (e.g., myocardial infarction, stroke and arrhythmias)
Malignant hyperthermia (rare)
Death
Which agents increase the likelihood of malignant hyperthermia?
Volatile anaesthetics (isoflurane, sevoflurane and desflurane)
Suxamethonium
What are the benefits of only anaesthetising the area required for surgery?
Better pain relief
Fewer medication side effects
Smoother recovery
What is a peripheral nerve block?
A local anaesthetic is injected around specific nerves, causing the area distal to the nerves to be anaesthetised.
The injection is performed under ultrasound guidance, sometimes with the help of a nerve stimulator, so that it can be accurately applied to the area around the targeted nerve.
When is a spinal block used?
Caesarean sections
Transurethral resection of the prostate (TURP)
Hip fracture repairs
Where is a spinal block inserted?
L3/4 or L4/5 spaces.
Must be injected below where the spinal cord terminates. The anesthesia is felt in the nerves below the level of injection.
What is used to test whether a spinal block has worked?
Cold spray on the area that should be affected
Takes 1-3 hours to wear off
What is an epidural?
An epidural involves inserting a small tube (catheter) into the epidural space in the lower back. This is outside the dura mater, separate from the spinal cord and CSF. Local anaesthetic medications are infused through the catheter into the epidural space, where they diffuse to the surrounding tissues and spinal nerve roots,
What medication is used for an epidural?
Levobupivacaine is often used, with or without fentanyl.
What are the risks of an epidural?
Headache if the dura is punctured, creating a hole for CSF to leak from (“dural tap”)
Hypotension
Motor weakness in the legs
Nerve damage (rare)
Infection, including meningitis
Haematoma (may cause spinal cord compression)
What is local anesthesia?
Local anaesthesia is used to numb a very specific area where a procedure is being performed. The local anaesthetic (e.g., lidocaine) is usually injected by the person performing the procedure (rather than involving an anaesthetist). This is usually used for smaller operations and procedures.
When would you use local anesthesia?
Skin sutures in A&E after a skin laceration
Minor surgery to remove skin lesions
Dental procedures
Hand surgery (e.g., carpal tunnel syndrome surgery)
Performing a lumbar puncture
Inserting a central line
Percutaneous procedures (e.g., percutaneous coronary intervention)
What does hyperventilation result in on an ABG?
Respiratory Alkalosis
Breathing in excess quantities removes CO2 quicker from the lungs -> reduced PaCO2
What is the management of a patient on Warfarin peri-operatively?
Stop Warfarin bridge with treatment dose low molecular weight heparin (LMWH) 5 days prior to surgery
Heparin is more easily reversible in the event of significant bleeding so is preferred
What are the ASA Grades?
ASA grade I is defined as normal healthy patients, who are non-smokers and with no/minimal alcohol intake.
ASA grade II is defined as patients with mild systemic disease e.g. well controlled diabetes or hypertension, current smoker, obesity (BMI 30-40), and mild lung disease.
ASA grade III is defined as patients with severe systemic disease e.g. poorly controlled diabetes or hypertension, COPD, morbid obesity (BMI >40), history of ACS/stroke/TIA >3 months ago.
ASA grade IV is defined as patients with severe systemic disease that is a constant threat to life e.g. MI/stroke/TIA within 3 months, severe valve dysfunction, severe reduction in ejection fraction, sepsis.
ASA grade V is defined as moribund patients not expected to survive the operation e.g. ruptured abdominal aortic aneurysm, massive bleed, intracranial haemorrhage with mass effect.
ASA grade VI is defined as a patient declared brain-dead whose organs are being removed for donation.
How do you insert an oropharyngeal airway?
Insert an oropharyngeal airway, initially upside down then rotated
Used for patients whose gag isn’t intact ( unconscious )
Commonly used before securing a more secure airway via intubation
What is the order for securing an airway?
Head tilt/ Chin lift maneuver whilst awaiting airway adjuncts
Airway adjuncts - Oropharyngeal airway insertion or Nasopharyngeal airway insertion
If these fail then use i-Gel or Laryngeal mask airway insertion
What is reading is used to confirm intubation?
End-tidal CO2
It measures the partial pressure of CO2 at the end of expiration. It is built into the ventilators used in anaesthetics.
What is Suxamethonium apnoea?
Suxamethonium apnoea occurs in individuals who have a defect in the plasma cholinesterase enzyme which normally breaks down suxamethonium. They are unable to break down suxamethonium and the patient will struggle to breathe on their own due to relaxation of the respiratory muscles
What must be stopped when starting a WHO Pain Ladder Step 3 drug?
Any Step 2 drugs
What is local anaesthetic systemic toxicity (LAST)?
LAST occurs when local anaesthetics are inadvertently absorbed into the systemic circulation, leading to CNS and cardiovascular manifestations.
What is a cluster headache?
Cluster headaches are usually severe, with associated watering of the eye. The eye is often bloodshot. The headache is unilateral, typically worse around the eye and attacks often come in clusters with multiple episodes over a short period.
What is the treatment for cluster headaches?
100% oxygen and subcutaneous sumatriptan
What is an epidural haematoma?
Epidural haematomas are a rare but serious complication of epidural anaesthesia. Symptoms and signs are classically consistent with those of cord compression, involving compression of upper motor neurons of both sensory and motor tracts
Hypereflexia
Hypertonia
Loss of continence
What is the treatment for local anesthetic toxicity?
20% intralipid infusion
Lipids bind to the local anaesthetics and reverse effects of local anaesthetic toxicity.
What is the inheritance of Malignant Hyperthermia?
Malignant hyperthermia is an autosomal-dominant-inherited disorder of skeletal muscle with mutations in the Ryanodine receptor 1. It causes hyper-metabolism (thus hyperthermia), increased oxygen uptake, increased carbon dioxide production, hyperkalaemia, tachycardia and a metabolic acidosis.
What does treatment with opioids involve?
Background dose ( given every 24 hours )
Rescue dose (1/6 of background dose)
What is the rescue dose for opioids?
The rescue dose is usually 1/6 of the background 24-hour dose. For example, if the patient is getting 30mg in 24 hours of modified-release morphine (15mg every 12 hours), each rescue dose will be 5mg, given every 2-4 hours as required.
Why is adequate pain control post-op important?
Mobilise
Ventilate their lungs fully (reducing the risk of chest infections and atelectasis)
Have an adequate oral intake
What is chronic pain?
Persists longer than 3 months
What are the different types of chronic pain?
Chronic primary pain – where no underlying condition can adequately explain the pain
Chronic secondary pain – where an underlying condition can explain the pain
What is the treatment of ARDS
Respiratory support
Prone positioning (lying on their front)
Careful fluid management to avoid excess fluid collecting in the lungs
What are the benefits of prone positioning
Reducing compression of the lungs by other organs
Improving blood flow to the lungs, particularly the well-ventilated areas
Improving clearance of secretions
Improving overall oxygenation
Reducing the required assistance from mechanical ventilation
What are the FiO2s of the different methods of oxygen therapy?
Oxygen can be delivered by several methods. The FiO2 (concentration of oxygen) will depend on the oxygen flow rate:
Nasal cannula: 24 – 44% oxygen
Simple face mask: 40 – 60% oxygen
Venturi masks: 24 – 60% oxygen
Face mask with reservoir (non-rebreather mask): 60 – 95% oxygen
What increases Positive End Expiratory Pressure? (PEEP)
High-flow nasal cannula
Non-invasive ventilation
Mechanical ventilation
What are the benefits of high flow oxygen?
Increasing the concentration of oxygen breathed per breath
It adds some positive end-expiratory pressure to help prevent the airways from collapsing at the end of exhalation
Dead space washout. The physiological dead space is the air that does not contribute to gas exchange because it never reaches the alveoli. Dead space air remains in airways and oropharynx, not adding anything to respiration and collecting carbon dioxide. High-flow oxygen effectively clears this and replaces it with oxygen, improving patient oxygenation.
What are the phases in BiPAP?
IPAP (inspiratory positive airway pressure) is the pressure during inspiration – where air is forced into the lungs
EPAP (expiratory positive airway pressure) is the pressure during expiration – stopping the airways from collapsing
How do you do NIV?
Non-invasive ventilation (NIV) involves using a full face mask, hood (covering the entire head) or a tight-fitting nasal mask to blow air forcefully into the lungs and ventilate them.
What is the best type of cannula for emergency?
Large Bore Cannula e.g 16G (Grey) or 14G (Orange)
What is the usual size cannula for IV fluids/drugs and Blood transfusion?
20G (Pink)
Which cannula would be recommended for rapid I?V fluid bolus
For rapid fluid resuscitation, a larger bore such as green (18G) would be the minimum recommended, which offers the balance between ease of insertion in an acute setting and speed of infusion.
What is the reversal agent for Tricyclic antidepressant overdose?
Sodium Bicarbonate
How early must COCP be stopped prior to surgery?
4 weeks
What can be useful in reducing ICP?
Short-term hyperventilation can be useful in lowering ICP. It reduces pCO2, which causes vasoconstriction of the cerebral arteries, leading to a rapid reduction in ICP.
How do you stabilise the C Spine and diagnose a C Spine injury?
Maintain neutral neck position and CT spine
Which antiemetic is best for PONV?
Ondansetron
A GCS score under what should be considered for intubation to secure the airway?
Less than 8, intubation must be considered to secure the airway
What is the next step step after IV cannulation has failed for rapid fluid resus in a cardiac arrest?
IV access is difficult due to severe hypotension
Call a trained individual for Intraosseous access
Most commonly in the proximal tibia
What should you swap Warfarin for prior to surgery?
LMWH
Shorter acting therefore more easily reversible in the case of bleeding
When is the Time Out performed on the WHO checklist?
Before the first incision is made
What are the guidelines for patients on antidiabetic medications the day of surgery?
Should be omitted the day before surgery
Omit on the day of surgery
Exception is morning surgery in patients who take BD - they can have the afternoon dose
Which anaesthetic drug acts as both a hypnotic and anti-emetic?
Propofol
What is capnography used to check for?
Accidental oesophageal intubation
Will show flat trace on the end-tidal carbon dioxide
Which drug is most commonly associated with Malignant Hyperthermia?
Suxamethonium
What type of inheritance is Malignant Hyperthermia?
Autosomal Dominant
Which imagine is best for diagnosing Anastomotic Leak?
CT Abdomen
Which agent is the choice for inducing a RSI?
Suxamethonium
When is bowel prep required for coloscopy?
The day before surgery
What is the treatment for a deep wound dehiscence?
A large sterile swab soaked in 0.9% saline can be used while waiting for senior help to arrived as this is an emergency
What electrolyte imbalance can be caused by Suxathemonium?
Hyperkalaemia
What is a complication of long term ventilation? e.g more than 7 days
Tracheo-oesophageal fistula formation
What are three types of regional anesthesia?
Spinal block (Into subarachnoid space)
Epidural ( Into epidural space
Peripheral nerve block ( Injected close to nerve )
