Anaesthetics Flashcards

Question 1

Q

NICE pre-operative guidelines: Summarise NICE guidelines on pre-operative investigations.

Answer

A

All types of surgery:

Communication and testing in primary care
Consideration of existing medicines
Check pregnancy status
Sickle cell disease - do not routinely offer testing before surgery
HbA1c testing for those with diagnosed diabetes only
Urine tests (microscopy & culture) only if the presence of UTI would influence the decision to operate
CXR - not routinely
Echocardiography & ECG - only if heart murmur + cardiac symptoms (breathlessness, pre-syncope, syncope or chest pain), or signs and symptoms of heart failure

ASA Grades

ASA 1 - normal health patient
ASA 2 - patient with mild systemic disease
ASA 3 - patient with severe systemic disease
ASA 4 - patient with severe systemic disease that is a constant threat to life

Minor Surgery

FBC - not routine
Haemostasis - not routine
Kidney function - ASA 3/4 at risk of AKI
ECG - ASA 3/4 if no results available from past 12 months
Lung function / ABG - not routine

Intermediate surgery

FBC - ASA 3/4 if CVD or renal disease not recently investigated
Haemostasis - ASA 3 / 4 - chronic liver disease, if taking anticoagulants that need to be modified or if clotting status needs to be tested
Kidney function - ASA 2 if risk of AKI, ASA 3/4 always
ECG - ASA 2 if CVD, renal disease or diabetes and ASA 3/4 always
Lung function / ABG - ASA 3/4 advice from senior anaesthetist if known or suspected respiratory disease

Major Complex Surgery

FBC - yes
Haemostasis - ASA 3/4 - chronic liver disease, if taking anticoagulants that need to be modified or if clotting status needs to be tested
Kidney function - ASA 1 if risk of AKI, ASA 2/3/4 always
ECG - ASA 1 consider for >65yrs with no ECG results from past 12 months, ASA 2/3/4 always
Lung function / ABG - ASA 3/4 advice from senior anaesthetist if known or suspected respiratory disease

Question 2

Q

Peri-operative risk scoring systems: summarise common peri-operative risk scoring systems (ASA and POSSUM).

Answer

A

ASA Grades

ASA 1 - normal health patient
ASA 2 - patient with mild systemic disease
ASA 3 - patient with severe systemic disease
ASA 4 - patient with severe systemic disease that is a constant threat to life

POSSUM - score of 1,2,4,8

Operative severity - minor, intermediate, major, major +
Number of operations within 30 days - 1, __, 2, >2
Blood loss per operation (ml) - <100, 101-500, 501-999, >1000
Peritoneal contamination - none, serous fluid,local pus, free bowel content, pus or blood
Presence of malignancy - none, primary only,nodal metastases, distant metastases
Mode of surgery - elective, ___, emergency resus of 2h possible and operation <24h after admission, emergency (immediate surgery <2h needed)

Question 3

Q

Peri-operative disease management: explain the principles of perioperative management of medical co-morbidities, including diabetes mellitus, hypertension, ischaemic heart disease, asthma, COPD, patients on anti-coagulant medications and sickle cell disease.

Answer

A

Minor Surgery

FBC - not routine
Haemostasis - not routine
Kidney function - ASA 3/4 at risk of AKI
ECG - ASA 3/4 if no results available from past 12 months
Lung function / ABG - not routine

Intermediate surgery

FBC - ASA 3/4 if CVD or renal disease not recently investigated
Haemostasis - ASA 3 / 4 - chronic liver disease, if taking anticoagulants that need to be modified or if clotting status needs to be tested
Kidney function - ASA 2 if risk of AKI, ASA 3/4 always
ECG - ASA 2 if CVD, renal disease or diabetes and ASA 3/4 always
Lung function / ABG - ASA 3/4 advice from senior anaesthetist if known or suspected respiratory disease

Major Complex Surgery

FBC - yes
Haemostasis - ASA 3/4 - chronic liver disease, if taking anticoagulants that need to be modified or if clotting status needs to be tested
Kidney function - ASA 1 if risk of AKI, ASA 2/3/4 always
ECG - ASA 1 consider for >65yrs with no ECG results from past 12 months, ASA 2/3/4 always
Lung function / ABG - ASA 3/4 advice from senior anaesthetist if known or suspected respiratory disease

Question 4

Q

Day Surgery: recall the criteria for the suitability of patients for day stay surgery.

Answer

A

Minimal blood loss expected
Short operating time (< 1 hour)
No expected intra-operative or post-operative complications
No requirement for specialist aftercare

Question 5

Q

Safety - Nil by mouth policy: explain the principles of nil by mouth policy before surgery.

Answer

A

Preoperative fasting is the practice of a patient abstaining from oral food and fluid intake for a time before an operation is performed. This is intended to prevent pulmonary aspiration of stomach contents during general anesthesia.

The amount of time you have to go without food or drink (fast) before you have your operation will depend on the type of operation you’re having. However, it is usually at least 6 hours for food, and 2 hours for fluids. You’ll be told how long you must not eat or drink for before your operation.

Question 6

Q

Safety - Transfusion reporting - recognize the importance of reporting blood units administered to the transfusion lab.

Answer

A

Ensuring that incidents are reported through the Trust Incident Reporting procedure, in line with the Incident Reporting and investigation Policy, and ensuring there is resultant organisational learning through the divisional structure and more widely across the trust.

Reporting of transfusion reactions or other incidents to the Blood Transfusion Laboratory.

Any unexpected event that has an actual or potential short-term or long-term detrimental effect on a patient must be reported according to the Trust’s Incident Reporting and Investigation Policy and to the Blood Transfusion laboratory.

Incident reporting should include ‘near miss’ episodes involving procedural errors which were detected in time to prevent a serious complication of blood transfusion, for example taking the blood sample for compatibility testing from the wrong patient or labeling the blood sample with another patient’s details.

Question 7

Q

Safety - controlled drugs: recognize the importance of recording the use of controlled drugs in the controlled drug register.

Answer

A

The establishment and operation of procedures to ensure safe management and use of controlled drugs by the healthcare body
Ensuring that an organization or person acting on behalf of (or providing services under arrangements made with) the healthcare body establishes and operates appropriate arrangements for securing the safe management and use of controlled drugs by that organization or person
Ensuring that up-to-date standard operating procedures (SOPs) regarding the management and use of controlled drugs are in place for the healthcare body and any person or organization acting on their behalf or providing services for them (see Box 1).
https: //www.guidelinesinpractice.co.uk/your-practice/receipt-supply-and-storage-of-controlled-drugs-must-be-recorded/309024.article

Question 8

Q

Respiratory - Ventilation: compare the differences between spontaneous ventilation and positive pressure ventilation.

Answer

A

Spontaneous breathing - the movement of gas in and out of the lungs that is produced in response to an individual’s respiratory muscles.

Continuous spontaneous ventilation - any mode of mechanical ventilation where every breath is spontaneous (e.g. patient triggered and patient cycled)

Positive pressure ventilation - a form of respiratory therapy that involves the delivery of air or a mixture of oxygen combined with other gases by positive pressure into the lungs.

Delivered in 2 forms:

Non-invasive positive pressure ventilation ( NIPPV) - e.g. face mask with tight seal
Invasive positive pressure ventilation (IPPV) - e.g. endotracheal tube or tracheostomy

BiPAP - Bi-level Positive Airway Pressure
- 2 levels of pressure - inspiratory positive airway pressure (IPAP) and lower expiratory positive airway pressure (EPAP) for easier exhalation

CPAP - Continuous Positive Airway Pressure

A constant level of pressure above atmospheric pressure is continuously applied to the upper airway
Intended to prevent upper airway collapse or reduce the work fo breathing (e.g. heart failure)

APRV - Airway Pressure Release Ventilation

Used for acute lung injury, ARDS and atelectasis after major surgery
Inverse ratio ventilation - exhalation time is shortened to usually less than 1 second to maintain alveoli inflation
Continuous pressure after a brief release - most efficient, conventional mode for lung-protective ventilation

Question 9

Q

Respiratory - Anaesthetic emergencies: recall the assessment and management of anaesthetic emergencies, including asthma, pneumothorax, haemothorax, anaphylaxis, foreign body aspiration.

Answer

A

ASTHMA

Assessment:

Spirometry measurement of expiratory volume in 1s (FEV1) expressed as a percentage of predicted normal value
Measurement of peak expiratory flow (PEF)
Pulse oximetry (& ABG in those < 92% sats or FEV1 < 30% without response to treatment)
Potassium levels (hypokalaemia caused by high-dose B-agonist therapy)

While recognizing the poor correlation between clinical signs and physiological measures, an FEV1 of <30% predicted is likely to be present in a patient who is unable to speak more than a few words with an arterial carbon dioxide tension (PaCO2) of >5.3 kPa (40 mm Hg), a quiet chest with the absence of audible wheezing, respiratory rate >30/min or pulsus paradoxus >20 mm Hg.

Management - OSHITME

O - OXYGEN - give via nasal cannula / mask to get O2 sats between 94-985
S - SALBUTAMOL - 2.5-5mg nebulised
H - HYDROCORTISONE - 100mg IV or PREDNISOLONE 40mg oral
I - IPRATROPIUM - 500mcg nebulised
T - THEOPHYLLINE - IV
M - MAGNESIUM SULPHATE - IV
E - ESCALATE CARE - if intubation and invasive ventilation are required

The administration of excessive oxygen is not without potential risks, including atelectasis and increased intrapulmonary shunting, and a reduction in cardiac output and coronary blood flow

NIPPV - useful for those with hypercapnic respiratory failure, as long as airway protection & can tolerate face mask. Will reduce work of breathing, respiratory muscle fatigue, decrease airway resistance, re-expand atelectatic areas of lung, decrease adverse hemodynamic effects of negative inspiratory pleural pressures - buying time for transfer to an ICU / HDU and for pharmacological intervention to take effect.

https://thorax.bmj.com/content/62/5/447

PNEUMOTHORAX & HAEMOTHORAX

Assessment

Clinical assessment
eFAST - extended focused assessment with sonography for trauma) or CXR if respiratory compromise
Immediate CT for those without severe respiratory compromise who are responding to resuscitation or whose haemodynamic status is normal
CXR or US as first-line for children under 16
Do not routinely use CT for first line to assess chest trauma in children under 16

Management
- Perform decompression before imaging only if they have either haemodynamic instability of severe respiratory compromise

ANAPHYLAXIS

Pathway:

Emergency treatment for a suspected anaphylactic reaction
Take timed blood samples for mast cell tryptase testing as soon as possible after emergency treatment, within 1-2 hours from onset of symptoms
Document acute clinical features - rapidly developing, life-threatening problems involving the airway (pharyngeal or laryngeal oedema) and/or breathing (bronchospasm wth tachypnoea) and/or circulation (hypotension, tachycardia) and associated skin and mucosal changes
Observation for 6-12 hours
Refer to specialist allergy service
Offer appropriate adrenaline injector as interim measure before specialist allergy appointment & offer information/support to the patient

FOREIGN BODY INSPIRATION

Presentation:

Sudden onset cough or persistent cough
Pneumonia
Atelectasis
Wheezing - focal monophonic wheezing or decreased air entry
Respiratory failure in severe cases
Witnessed episode of choking

Management:

Neck and CXR
Expiratory CXR - allows visualisation fo air trapped by a valve-like effected due to partial obstruction of bronchial lumen, may see a mediastinal shift
Life-threatening - 5 back blows or abdominal thrusts & chest compressions
Bronchoscopy

Question 10

Q

Respiratory - Observations: recall the measurement and normal values of physiological parameters, including pulse oximetry, capnography and blood gas results.

Answer

A

Pulse Oximetry

Normal 95-100%
COPD 88-92%
<90% abnormally low

Capnography

End-tidal CO2 usually 35-45 mmHg
Shows how much CO2 is present at each phase of the respiratory cycle, normally has a rectangular shape
Measures and displays respiratory rate (12-20 breaths per minute)

Blood Gas Results

pH - 7.35-7.45
PaO2 - 75-100mHg
PaCO2 - 35-45mmHg
HCO3 - 22-26 meq/L

Question 11

Q

Circulation - Blood pressure monitoring: recall the indications for non-invasive and invasive monitoring.

Answer

A

Invasive:

Induced, on-going or anticipated hypotension or wide variations in blood pressure
End-organ disease requiring precise pressure regulation
Need for frequent or multiple blood gas measurements

Non-invasive:
- Patients who are at risk of haemodynamic instability

Question 12

Q

Circulation - IV fluids: explain the rationale of fluid administration and the difference between colloids and crystalloids.

Answer

A

Colloids

A phase-separated mixture in which one substance of microscopically dispersed insoluble or soluble particles are suspended throughout another substance
Particles are too large to pass semi-permeable membranes so they stay in the intravascular spaces longer than crystalloids
E.g. albumin, dextran, hydroxyethyl starch

Crystalloids

Low-cost salt solutions with small molecules, which can move around easily when injected into the body
E.g. saline
Do not use crystalloids for patients with active bleeding

Adults (>16) - 1 unit of plasma to 1 unit of red blood cells to replace fluid volume

Children (<16) - 1 part plasma to 1 part red blood cells and base volume on child’s weight.

Question 13

Q

Circulation - Blood transfusion: recall the triggers for giving a blood transfusion.

Answer

A

Symptomatic anaemia - SOB, dizziness, congestive heart failure, decreased exercise tolerance
Acute sickle cell crisis
Acute blood loss of more than 30% of blood volume
Hb <8 g/dL (or <80)

Question 14

Q

Pain relief - Multi-modal analgesia: recall the principles of multimodal analgesia.

Answer

A

Combination of regional anaesthesia (single-shot or continuous central neuraxial or peripheral nerve blocks or local infiltration analgesia), opioid analgesics and non-opioid systemic analgesics (paracetamol, NSAIDs).

Question 15

Q

Pain relief - Pain: summarise approaches to the management of acute and chronic pain.

Answer

A

https://midessexccg.nhs.uk/about-us/the-library/medicines-management/clinical-pathways-and-medication-guidelines-1/chapter-4-central-nervous-system-2/3345-acute-and-chronic-combined-pain-guidelines-august-2019/file

Question 16

Q

Pain relief - WHO pain ladder: explain the WHO pain ladder.

Answer

A

Mild pain
- Non-opioid + adjuvant therapy

Mild to Moderate pain
- Weak opioid or multimodal + non-opioid + adjuvant therapy

Moderate to Severe Pain
- Strong opioid + non-opioid + adjuvant therapy

Severe to Very Severe Pain
- Interventional treatments + non-opioid + adjuvant therapy

Question 17

Q

Pain relief - Regional analgesia/anaesthesia: explain the rationale and management of regional analgesia/anaesthesia

Answer

A

Regional anaesthesia may be classified anatomically as follows: (a) infiltration anaesthesia (extravascular or intravascular); (b) peripheral nerve blockade (minor or major nerve block); and (c) central neural blockade (epidural or subarachnoid block).

The local anaesthetic agents commonly employed for regional anaesthesia may be classified according to their relative potency and duration of activity into: (1) agents of low potency and short duration, e.g. procaine and chloroprocaine; (2) agents of moderate potency and duration, e.g. lignocaine (lidocaine), mepivacaine and prilocaine; and (3) agents of high potency and long duration, e.g. amethocaine (tetracaine), bupivacaine and etidocaine.

In general, the onset, duration and quality of regional anaesthesia are enhanced by an increase in dose achieved by either an increase in concentration or in the volume of anaesthetic solution, and by the concomitant use of a vasoconstrictor drug, adrenaline (epinephrine). However, the local anaesthetic properties of the intrinsically more potent and longer acting agents are influenced less by the addition of adrenaline, particularly when such agents are employed for central neural blockade of the epidural type.

Question 18

Q

Pain relief - Analgesic Drugs: recall dosage, mode of administration, indications and contraindications of common analgesic drugs.

Answer

A

NON-OPIOIDS

Paracetamol

No demonstrable anti-inflammatory activity
Less irritant to stomach
Overdose causes hepatic damage not apprent for 4-6 days

Aspirin
Indications: Headache, transient MSK pain, dysmenorrhoea, pyrexia, anti-platelet
Contraindications: Gastric irritation (can se enteric coated preparations), warfarin sodium interaction

Other NSAIDS

Chronic disease + pain + inflammation
Short-term treatment of mild to moderate pain
Dysmenorrhoea, secondary bone tumours, post-operative analgesia

OPIOIDS + NON-OPIOIDS

Reduce scope for effective titration of individual components in management of pain of varying intensity
E.g. 8mg codeine phosphate + paracetamol / aspirin
Full dose opioid - e.g. 60mg codeine phosphate
SE: N&V, constipation, drowsiness, respiratory depression, dependence

ADDITION OF CAFFEINE

Stimulant
Enhances analgesic effect
SE: Alerting effect, mild habit-forming effect, provocation of headache

MORPHINE

Most valuable opioid analgesic for severe pain
SE: N&V, euphoria, mental detachment
Given regularly every 4 hours, or every 12-24 hours as modified-release preparations

BUPRENORPHINE

Opioid agonist and antagonist properties
Withdrawal symptoms, pain, abuse potential, dependence
Longer duration of action than morphine - 6-8 hours
Partially reversed by naloxone hydrochloride

DIAMORPHINE HYDROCHLORIDE (Heroin!)

Less nausea and hypotension
Palliative care!
Effective doses injected in smaller volumes

ALFENTANIL, FENTANYL, REMIFENTANIL

Injection for intra-operative analgesia
Available in transdermal drug delivery system as a self-adhesive patch changed every 72 hours

METHADONE HYDROCHLORIDE

Less sedating than morphine, acts for longer periods
Do not administer more than twice daily to avoid the risk of accumulation and opioid overdose
Used instead of morphine in occasional patient who experiences excitation or exacerbation of pain with morphine

OXYCODONE HYDROCHLORIDE

Efficacy and side-effect profile similar to that of morphine
Second-line drug if morphine is not tolerated or does not control the pain

PENTAZOCINE

Agonist and antagonist properties and precipitates withdrawal symptoms - e.g.pain in patients dependent on other opioids
Avoided after MI as may increase pulmonary and aortic blood pressure as well as cardiac work

PETHIDINE HYDROCHLODIRDE

Prompt but short-lasting analgesia
Less constipating
Higher doses is less potent
Used in labour, but morphine or diamorphine hydrochloride is preferred for obstetric pain

TAPENTADOL

Opioid receptor agonist
Inhibits noradrenaline reuptake
N&V & constipation less likely to occur

TRAMADOL HYDROCHLORIDE

Opioid effect
Enhancement of serotonergic and adrenergic pathways
Fewer side effects, psychiatric reactions have been reported though

CODEINE PHOSPHATE
- Relief of mild to moderate pain where other painkillers such as paracetamol or ibuprofen have proved ineffective

DIHYDROCODEINE TARTRATE

Similar efficacy to codeine phosphate
Higher doses provide additional pain relief at the cost of more nausea and vomiting

MEPTAZINOL

Low incidence of respiratory depression
Onset 15 minutes, length of action 2-7 hours

NB: Post-operatively - morphine most widely used.

Question 19

Q

Pain relief - Anti-emetic drugs: recall dosage, mode of administration, indications and contraindications of common anti-emetic drugs.

Answer

A

ANTIHISTAMINES - e.g. promethazine
- Vomiting during pregnancy

PHENOTHIAZINES

Dopamine antagonists
Act centrally by blocking CTZ
For N&V associated with diffuse neoplastic disease, radiation sickness, emesis caused by opioids, GA, cytotoxics
E.g. prochlorperazine, perphenazine, trifluoperazine, chlorpromazine hydrochloride
Can be administered by rectal suppositories, buccal tablets

HALOPERIDOL & LEVOMEPROMAZINE
- In terminal illness - antipsychotic drugs

METOCLOPRAMIDE HYDROCHLORIDE

Acts directly on GI tract
Superior to phenothiazines for emesis associated with gastroduodenal, hepatic and biliary disease

DOMPERIDONE

Acts at CTZ
Less likely to cause sedation and dystonic reactions as doesn’t cross BBB
Used to treat nausea caused by dopaminergic drugs in Parkinson’s

GRANISETRON & ONDANSETRON
- In patients receiving cytotoxics and post-operative N&V

PALONOSETRON

Moderately or highly emetogenic cytotoxic chemotherapy
Combination with netupitant (neurokinin 1-receptor antagonist)

DEXAMETHASONE

Associated with cancer chemotherapy
Used alone or in combination with metoclopramide hydrochloride, prochlorperazine, lorazepam, 5HT3-receptor antagonist

APREPITANT & FOSAPREPITANT & ROLAPITANT

Neurokinin 1-Receptor Antagonists
Aprepitant - chemotherapy
Fosaprepitant - prevention of cisplatin-based chemotherapy
Rolapitant - chemotherapy prevention
Given with dexamethasone + 5HT3-receptor antagonist

NABILONE

Synthetic cannibinoid
Add on treatment for chemotherapy-induced nausea and vomiting unresponsive to conventional anti-emetics

PREGNANCY

Antihistamine - e.g. promethazine
Prochlorperazine or metochlopramide hydrochloride alternative
24-48 hours without symptoms settling then seek specialist opinion
Hyperemesis gravidarum - regular antiemetic therapy, IV fluids, electrolytes, nutritional support, thiamine

POST-OP

5HT3-receptor antagonists
Droperidol
Dexamethazone
Phenothazines - e.g. prochlorperazine
Antihistamines - e.g. cyclizine

MOTION SICKNESS

Hyoscine hydrobromide
Antihistamines
Promethazine (if require sedative effect)
Cyclizine or Cinnarizine - less sedating

NB: Domperidone, metochlopramide hydrochloride, 5HT3-receptor antagonists, phenothiazines ineffective in motion sickness.

VESTIBULAR DISORDERS

Betahistine dihydrochloride - analogue of histamine
Vertigo, tinnitus, hearing loss associated with Meniere’s disease
Diuretic combined with salt restriction - vertigo associated with Meniere’s disease (also antihistamines - cinnarizine, phenothiazines - prochlorperazine)

Question 20

Q

Temperature control - Homeostasis: recall the normal homeostatic control of temperature and explain how this is affected by anesthesia.

Answer

A

Perioperative hypothermia develops in three distinct phases:

(1) anaesthetic-induced vasodilation during induction of anaesthesia results in core-to-peripheral redistribution of body heat and decreases core temperature 1–1.5°C during the first hour of general anaesthesia
(2) subsequently core temperature decreases linearly as heat loss to the environment exceeds metabolic heat production
(3) after 3–5 h of anaesthesia, core temperature often stops decreasing.

This core temperature plateau results from reactivation of thermoregulatory vasoconstriction which decreases cutaneous heat loss and constrains metabolic heat to the core thermal compartment.

Perioperative hypothermia is associated with numerous complications such as myocardial ischaemia, increased risk of wound infection and coagulopathy. On the other hand temperatures only 1–3°C below normal provide substantial protection against cerebral ischaemia and hypoxaemia in numerous animal species. Consequently, most anaesthesiologists believe mild hypothermia is indicated during operations likely to cause cerebral ischaemia such as carotid endarterectomy and neurosurgery or cardiac procedures.

Question 21

Q

Temperature control - Warming devices: recall methods of warming patients during surgery, including warm air blanket, fluid warmers and heat moisture exchangers.

Answer

A

WARM AIR BLANKET
Filters air and then forces warm air through a disposable blanket which covers the patient before, during and after surgery

FLUID WARMERS
A medical device used in healthcare facilities for warming fluids, crystalloid, colloid, or blood product, prior to being administered (intravenously or by other parenteral routes) to body temperature levels in order to prevent hypothermia in physically traumatized or surgical patients.

HEAT AND MOISTURE EXCHANGER
Devices used in mechanically ventilated patients intended to help prevent complications due to drying of the respiratory mucosa, such as mucus plugging and endotracheal tube (ETT) occlusion.

Question 22

Q

Emergence: recognise the requirements for emergence from anaesthesia and the indications for ongoing sedations.

Answer

A

Receptors:

Gamma-aminobutyric acid type A (GABAA) receptors
N-methyl D-aspartate (NMDA) receptors
α2 receptors
Opioid receptors
Neuronal hyperpolarization-activated cyclic nucleotide-gated (HCN) family channels
Two-pore domain potassium (K2P) channels.

Functionally, the drug-receptor interaction leads to several changes in cortical and subcortical signals, inducing alterations in the connectivity across brain regions. Complex mechanisms underlie alterations of cortico-cortical and cortical-subcortical functional connectivity. The different general anesthetics activate different molecular patterns, expressed as different functional alterations in brain connectivity and different electrophysiological correlates.

Volatile agents, for instance, interfere with frontal-posterior connectivity and this effect reverberates on the gamma (20–60 Hz) oscillations which have a pivotal role in arousal and maintenance of consciousness.

Again, propofol provokes a quick anteriorization of alpha rhythms (8–12 Hz) and promotes the propagations of slow-delta oscillations across the cortex, inducing a functional disruption of the connectivity between distinct cortical areas.

Yet, dexmedetomidine impairs the thalamo-cortical functional connectivity mostly expressed as spindle waves (12–16 Hz) in the frontal area.9 The matter is extremely complex, as alterations in connectivity within distinct brain regions lead to different depths of anesthesia.

Thus, changes in thalamic-cortical connectivity lead to the induction of the loss of consciousness (LoC) whereas changes in the cortico-cortical functional connectivity and a further impact on cortico-subcortical functioning induce the completion of the induction mechanism and the maintaining of the surgical anesthesia status.

During the AE phase, mechanisms responsible for LoC and anesthesia maintenance are gradually reversed. Nevertheless, these “passive” processes are associated with specific awakening mechanisms.

Of note, these active processes include several ascending arousal brain pathways where the thalamus plays a key role.

Apart from the thalamus, other arousal-promoting brain regions such as the substantia nigra, the ventral and laterodorsal tegmental areas of the midbrain, the dorsal raphe, and the locus ceruleus (LC) as well as the basal forebrain (BF), and lateral hypothalamus are involved. Thus, it has been postulated the existence of a mesencephalic arousal pathway.

The hypothalamus is also implicated in these wake-promoting processes. Orexin also known as hypocretin, is an endogenous wakefulness-promoting substance.

Hypothalamic orexinergic neurons are involved in both the sleep-to-wake transition and maintenance of wakefulness.

This orexinergic system is functionally connected with other structures such as basal ganglia that regulate the awakening processes during the AE. Interestingly, serotonergic neurons in the dorsal raphe nucleus receive projections from orexinergic neurons, concurring in sleep-wakefulness modulation.

Among these complex arousal networks, there are the LC norepinephrine (LCNE) system and posterior hypothalamic histaminergic tuberomammillary nuclei (TMN). In particular, the LCNE is the main structure of the so-called LCNE arousal system which includes the posterior cingulate cortex, thalamus, and basal ganglia. Another arousal pathway is the brainstem ascending reticular arousal system (ventral and dorsal pathways) which originates from the pontine/midbrain regions and develops cholinergic cortical projections through interactions with the thalamus, hypothalamus, and the BF region.

In summary:

i) AE is not just a passive process due to a cessation of the action of general anesthetics
ii) the arousal mechanisms at the end of GA are produced by structures deeper in the brain, rather than being activated within the neocortex
iii) rather than a single awakening system, it is more correct to refer to an arousal network. It is composed by the cholinergic basal forebrain, dopaminergic ventral tegmental area, anterior cingulate cortex, orexinergic hypothalamic, serotonergic raphe, LCNE, and histaminergic TMN neurons.

Question 23

Q

Recovery - Observations: recall the observations measured in recovery.

Answer

A

HR
RR
SpO2
BP
Temperature
Sedation Score - AVPU, Michigan sedation score, GCS
Pain Score
Nausea Score

Physical assessment:

Airway, Breathing, Circulation & Disability Assessment
Baseline Observations including RR, Resp effort, SpO2, HR, BP, Temp
O2 requirements
IV fluids
Analgesia
Urine output
Reportable blood loss
Assessment of wound sites / dressings
Presence of drains and patency of same
NGT in situ

Question 24

Q

Recovery - Discharge: recall the criteria for discharge from recovery.

Answer

A

PACU Discharge Criteria:

Clinical observations within age-appropriate limits
Observations which fall within shaded areas of clinical observation chart, should be managed following the Medial Emergency Response Procedure
Core temperature >36 degrees or >36.6 degrees for neonates
Sedation score 2 or less (UMSS)
No active vomiting
Pain Managed

Question 25

Q

Recovery - Hand-over techniques: explain effective staff hand-over techniques.

Answer

A

Phoning a senior:

Prepare what you want to say in advance
Identify yourself at the start of the call
Have relevant information at hand
Deliver the key relevant information
Speak clearly at all times
Offer to repeat information
Check the information is heard and understood
Clarify instructions by paraphrasing
Document the call

SBAR:

Situation - identify yourself (name and role), patient, Dr you are handing over to
Background - reason for admission, relevant history, background since admission, current status
Assessment - vital signs, clinical impression, concerns
Recommendation - explain specifically what you need / request for guidance & time frame, make suggestions, clarify expectations

Question 26

Q

Post-operative documentation - Early warning scores: recall clinical parameters documented in the peri-operative period and recognize the value of early warning scores.

Answer

A

EWS2 is used across the NHS in England. It’s used by all ambulance trusts and 76% of acute trusts.

The NEWS2 scoring system measures 6 physiological parameters:

respiration rate
oxygen saturation
systolic blood pressure
pulse rate
level of consciousness or new-onset confusion
temperature.

Question 27

Q

Post-operative complications - explain the assessment and management of postoperative complications, including pain, tachycardia, hypotension, low urine output, confusion, low oxygen saturation and reduced conscious level.

Answer

A

GENERAL POST-OPERATIVE COMPLICATIONS

IMMEDIATE

Primary haemorrhage (starting during surgery) or reactionary haemorrhage (following postoperative increase in blood pressure) - replace blood loss and may require return to theatre to re-explore the wound.
Basal atelectasis: minor lung collapse.
Shock - blood loss, acute myocardial infarction, pulmonary embolism or septicaemia.
Low urine output: inadequate fluid replacement intra-operatively and postoperatively.

EARLY

Pain.
Acute confusion: exclude dehydration and sepsis. May also be due to other various causes, including pain, sleep disturbance, medication or metabolic disturbances.
Nausea and vomiting: analgesia or anaesthetic-related; paralytic ileus.
Fever (see ‘Postoperative fever’, below).
Secondary haemorrhage: often as a result of infection.
Pneumonia.
Wound or anastomosis dehiscence.
DVT.
Acute urinary retention.
Urinary tract infection (UTI).
Postoperative wound infection.
Pressure sores.
Bowel obstruction due to fibrinous adhesions.
Paralytic Ileus.

LATE

Bowel obstruction due to fibrous adhesions.
Incisional hernia.
Persistent sinus.
Recurrence of reason for surgery - eg, malignancy.
Keloid formation.
Cosmetic appearance - depends on many factors (best discussed with surgeon).

POST-OPERATIVE FEVER

0-24 hours

Tissue damage and necrosis at the operation site.
Haematoma.
Pre-existing infection.

24-72 hours

Pulmonary atelectasis.
Chest infection.
Specific infections related to the surgery - eg, biliary infection following biliary surgery, UTI following urological surgery.
Blood transfusion or drug reaction.

Days 3-7

Bronchopneumonia.
Sepsis.
Wound infection.
Drip site infection or phlebitis.
Abscess formation - eg, subphrenic or pelvic, depending on the surgery involved.
Anastomosis leak.

After 7 days

DVT.
Pulmonary embolus.

Question 28

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