Agitation and Sedation

Question 1

Give some causes of acute confusion in the postoperative patient

Answer 1

Pain, anxiety and disorientation
Sepsis: systemic infection, or localised to chest, urinary
tract,wound
Hypoglycaemia, or hyperglycaemia with ketoacidosis
Respiratory failure, leading to hypoxaemia and/or
hypercarbia: precipitating causes apart from chest infection include acute pulmonary oedema, pneumothorax,pulmonary embolism, and sputum retention/atelectasis
Hypotension of any cause: e.g. bleeding,myocardial
infarction, or arrhythmia leading to reduced cerebral
perfusion
Acute renal or hepatic failure
Electrolyte disturbance: most commonly hypo or
hypernatraemia
Water imbalance: both dehydration and water overload
Acute urinary retention – especially in the elderly
Drugs: opiate analgesia, excess sedative drugs,
anticholinergics

Question 2

Which investigations should you perform?

Answer 2

A full history and examination
Arterial blood gas analysis: which determines the base
excess and respiratory function
Serum glucose
Full blood count
Serum electrolytes: sodium, potassium, calcium,
phosphate, magnesium, lactate (strictly speaking,
a metabolite), urea and creatinine
Liver function tests
Sepsis screen: blood cultures, wound swab, urine and
sputum cultures
Radiology: such as a chest radiograph
ECG: for arrhythmias or myocardial infarction

Question 3

What is the purpose of sedation in the critical care setting?

Answer 3

A reduction in the level of consciousness, but
with retention of verbal communication.

From a practical perspective in the intensive care
setting, they are used to permit tolerance of endotracheal
tubes, oral suction and other bed-side procedures

Light sedation for minor procedures
Anxiolytic and light sedative can be used premedication before major surgery
For confused patients on the ward (take care to investigate the cause)
For ET intubation

Question 4

How is the level of sedation determined?

Answer 4

The most commonly
employed of these is the Ramsay scoring system that
describes six levels of sedation
Level 1: The patient is anxious and agitated or restless or
both
Level 2: The patient is co-operative, orientated and
tranquil
Level 3: Responds to commands only
Level 4: Asleep. Brisk response to glabellar tap or loud
auditory stimulus
Level 5: Asleep. Sluggish response to glabellar tap or loud
auditory stimulus
Level 6: Asleep. No response to glabellar tap or loud
auditory stimulus
The ideally sedated patient attains levels 2–4.

Question 5

Which class of drugs may be used?

Answer 5

Benzodiazepines
Inhalation anaesthetic
Opiate analgesic

Question 6

Which of these are the most commonly used for sedation in critical care?

Answer 6

The most commonly used sedative drugs are propofol, benzodiazepines
and the opioid analgesics

Question 7

Define anxiolysis

Answer 7

The relief of apprehension and uneasiness without alteration of awareness

Question 8

Define amnesia

Answer 8

Loss of memory of an event or period (retrograde or antegrade)

Question 9

Define sedation

Answer 9

Depression of a patient’s awareness of the environment and reduction of his/her responsiveness to external stimulation

conscious sedation is light sedation in which the patient maintains his or
her airway reflexes and ability to cooperate
• deep sedation is a more profound depression of the response to stimulation
in which airway reflexes are not maintained

Question 10

Define analgesia

Answer 10

Relief of pain without sedation (some analgesics may have a sedative effect)

Question 11

Define anaesthesia

Answer 11

A state of unconsciousness with no perception of noxious stimuli

Question 12

How do benzodiazepines work?

Answer 12

act by stimulating GABA receptors in

the CNS -> chloride influx, hyperpolarization and decreased neuronal excitation

Question 13

What are the main actions of benzodiazepines

Answer 13

Anxiolysis and sedation
Amnesia (most profound with midazolam)
Anticonvulsant
Respiratory and cardiovascular depression

Question 14

Midazolam

Answer 14

Most commonly used benzodiazepine for minor procedures
• Water soluble
• Short half-life
• Profound amnesic effect in many patients
• Rapid onset
• Metabolized by hepatic microsomal system, so suitable for use in renal failure
• In overdose can cause respiratory and cardiac depression
• All patients having midazolam sedation should have intravenous access and
pulse oximetry (see ‘Pulse oximetry, Chapter 118, page 491); ECG monitoring
and resuscitation facilities should be available (including flumazenil). Patients
should not drive or operate heavy machinery for 48 hours afterwards

Question 15

Lorazepam

Answer 15

Water soluble
• Intermediate half-life
• Intermediate onset
• Suitable for infusion as little accumulation
• Cleared by hepatic conjugation.

Question 16

Diazepam

Answer 16

Not water soluble – usually prepared in glycerol
• Intermediate to long half-life
• Can be given intravenously, orally or rectally
• Good anticonvulsant acutely
• Hepatic metabolites are active and have long half-lives, so not suitable for
infusion.

Question 17

Propofol

Answer 17

Non-barbiturate sedative
Substituted isopropyl phenol compound prepared in a 10 per cent lipid
emulsion (white emulsion)
• Anaesthetic induction agent: some short operations can be performed solely on
propofol without the use of a volatile agent
• Rapid onset and short half-life
• Clearance not affected by renal or hepatic dysfunction
• Respiratory and cardiovascular depressant
• Good agent for sedation in patients receiving mechanical ventilation
• Prolonged infusion in paediatrics is associated with lactic acidosis.

Question 18

Etomidate

Answer 18

Non-barbiturate imidazole
• Commonly used on rapid induction intubation alongside a muscle relaxant such
as suxamethonium
• Rapid onset of action and a short but dose-dependent duration of action
• Cardiovascular effects minimal
• Can be used as a short-term sedative for procedures
• Depresses adrenal cortex in the long term – not suitable for infusion.

Question 19

Opioids

Answer 19

Opioids are agents that induce systemic analgesia, some anxiolysis and mild sedation.
They do not induce amnesia of any significance. Examples: morphine, fentanyl.
• Main type of analgesic used in surgery
• Rapid onset and usually intermediate half-life
Can cause respiratory depression in overdose
• Can be given intravenously, intramuscularly, intrathecally, transdermally or orally
in some cases
• Reversal using naloxone (see below)
• Given as titrated bolus in acute pain
• Commonly used in PCA
• Long-acting opioids (fentanyl patches or MST Continus) given in palliative care
or chronic pain.

Question 20

What is the competitive antagonist of the opioid class of drugs.

Answer 20

Naloxone

Question 21

What is the competitive antagonist of the benzodiazepine class of drugs

Answer 21

Flumazenil