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A Brief Introduction to Critical Care
9
physician’s associate roles to supplement and complement the work done
by regular critical care nurses and doctors. They may take full part in
daily physical assessments of patients, contribute to management plans,
perform procedures and assist with resuscitation.
Other specialists who work closely with ICU include microbiology, pallia-
tive care, transplant surgeons, specialist physicians, pain teams, specialist
nurses in organ donation, chaplains, electrophysiologists, occupational
therapists and perfusionists.
Psychological and psychiatric issues in the ICU
Patients in critical care are vulnerable to both pre- existing psychiatric diagnoses
and acute, ICU-
related problems. Approximately 50% of critically ill patients
suer serious emotional distress (Richard-
Belle, BMJ Open, 2018). Underlying
psychiatric issues may be directly related to the patient’s admission–e.g. drug
overdose, medication compliance issues leading to status epilepticus, adverse
reactions to antipsychotic medications. Psychiatric diagnoses may co-
exist
unrelated to the admitting diagnosis but can make managing patients chal-
lenging. Patients may present to ICU while being treated under a Section of
the Mental Health Act. This is discussed in Case 18.
Acutely, up to 80% of patients develop delirium while in ICU. Delirium can
be hyperactive, hypoactive or mixed. Delirium is discussed further in Case 11.
The psychological sequalae following a critical care admission can include
PTSD, body image issues, poor sleep, depression and psychosocial problems,
including relationship diculties and trouble returning to work. These issues,
which dramatically aect a patient’s long- term physical and psychological health,
can sometimes be directly traced back to traumatic experiences in ICU, e.g. a period
of delirium, a painful experience, a miscommunication. Although many potential
sources of distress cannot be avoided, healthcare workers in ICU can make eorts
to ensure good analgesia, minimise distressing noises and try to reassure and orien-
tate patients with good communication, even when sedated. ICU follow- up clinics
can provide valuable support for patients and useful insights for the healthcare
team. Multidisciplinary input from psychologists, ICU nurses, physiotherapists
and doctors is vital for identifying and managing long- term sequalae.
The admitting clinician should pay attention to any pre- existing psychiatric diag-
noses and review medicine prescriptions. Adverse eects of antipsychotic drugs can
be multisystemic and include hepatic dysfunction (e.g. chlorpromazine), sudden
cardiac death (e.g. thioridazine), prolonged QTc interval (e.g. haloperidol), renal
dysfunction (e.g. risperidone) and blood dyscrasias (e.g. clozapine). The admit-
ting clinician should be aware that some antipsychotics can be administered in
depot form and asenapine is available as a transdermal patch in some countries.
Drug history should also include over- the- counter remedies, smoking, alcohol
and illegal drugs.
Communication
Communication is key in ensuring that the patient’s and relatives’ experience
is as good as possible. Good communication can help to mitigate some of
the negative psychological impacts of an ICU admission. Discussion with the
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Clinical Cases in Critical Care
10
patient themselves or, if incapacitated, their next of kin should be an early
priority. The clinician should try to nd a safe and quiet space, take a col-
league for support, avoid interruptions from phones or bleeps, and document
everything thoroughly. Additional medical history should be obtained from
the patient, next of kin, general practitioner, previous hospital or clinic notes,
and the police/law enforcement if necessary. When providing information, you
must always consider the patient’s right to condentiality. Consult the General
Medical Council’s guidance on using and disclosing patient information and
if in doubt, discuss with the hospital legal team.
If the patient is unconscious, you will most often be communicating with
the next of kin. It is usually wise to begin managing their expectations early
on, given the high overall mortality in the critical care patient population.
Psychological issues amongst ICU staff
The COVID- 19 pandemic highlighted the vulnerability of critical care sta to
PTSD, depression, anxiety and burnout. Psychological support and resilience
training should be available for sta. Hot and cold debrieng sessions can be use-
ful (i.e. at the time of the event and after a timely delay), as can Schwartz rounds
and Balint groups (group sessions where professionals gather to reect upon the
social and emotional aspects of their work). Encouraging the MDT to debrief
together can improve teamwork and help build support networks. Sta should
also be encouraged to take annual leave and maintain their interests outside work.
Infection control
According to the World Health Organization (WHO), approximately 30% of
patients in ICUs in high- income countries are aected by healthcare- associated
infection (HCAI or nosocomial infection). Critical care patients are at particular
risk due to invasive procedures, relative immune suppression and exposure to
broad- spectrum antimicrobials.
Scrupulous infection control is mandatory. GPICS V2.1 recommends that all
sta in ICU observe the WHO ‘Five Moments For Hand Hygiene’. There should
be documentation and audit systems in place for infection control practices,
particularly with regard to invasive procedures, antibiotic stewardship, sur-
veillance for nosocomial infection, and environmental infection control (e.g.
surface and fomite cleaning, deep cleaning). Many units observe ‘gloves and
aprons’ and ‘bare below the elbows’ policies.
Cross- infection screening is advised, particularly where patients have been
transferred between healthcare institutions, including care homes and rehabilita-
tion facilities. Microbes implicated in cross- infection include methicillin-resistant
Staphylococcus aureus (MRSA), carbapenemase- producing organisms (CPO),
Clostridium dicile (C. di) and Acinetobacter. There have been deadly outbreaks
of these organisms in ICUs and infections are dicult to treat. There is consider-
able associated morbidity and mortality. ‘Care bundles’ have been used to reduce
the incidence of certain nosocomial infections such as ventilator- associated
pneumonia and catheter- related site infection (e.g. Matching Michigan).
Space between beds should be sucient to prevent cross- infection and ICUs
should have isolation areas available for patients with contagious diseases such
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A Brief Introduction to Critical Care
11
as tuberculosis (TB) and inuenza. Isolation rooms should have pressurised
antechambers to oer protection from the environment for vulnerable, immu-
nocompromised patients, or to protect the environment from contagions.
There should be clear protocols for managing incidences of sta exposure–for
instance, exposure to blood-
borne viruses, measles or TB.
Clinical governance and quality assurance
The UK Department of Health (DoH) stated in 1998 that clinical governance is the
‘framework through which healthcare organisations are accountable for continu-
ously improving the quality of their services and safeguarding high standards of
care by creating an environment in which excellence in clinical care will ourish’.
Standards are set by organisations such as the DoH UK, WHO, Faculty of
Intensive Care Medicine (FICM) and the Intensive Care Society (ICS). The ICS
publishes the Guidelines for the Provision of Intensive Care Services; version
2.1was published in 2022: GPICS V2.1.
There should be local leads (consultant and nurse) for audit and quality
improvement. Local clinical governance meetings allow presentation and
discussion of clinical audit, quality improvement and morbidity and mortality
data. In addition to local audit meetings, there are larger organisations such
as the Intensive Care National Audit and Research Centre (ICNARC) which
regularly publishes reports on national data.
Most hospitals have systems in place to facilitate incident reporting (e.g.
Datix). In addition, certain issues warrant root-
cause analysis or After Action
Review, e.g. cases of cross- infection with MRSA.
Various signals have been considered as quality- of- care indicators in the
ICU, e.g. incidences of ventilator- associated pneumonia (VAP), accidental
extubation or pulmonary thromboembolism. However, there is no consensus
regarding this.
It can be a challenge to keep up to date with current trends in critical care
medicine while working a busy job. Journal clubs are a useful way to share
knowledge, encourage critical thinking and develop skills in analysis. Not all
clinicians need to carry out research, but all should be able to understand the
process and appraise the results.
The GRADE system can be used to assess the quality of evidence– Grading
of Recommendations, Assessment, Development and Evaluation. GRADE
reviews limitations, internal validity, inconsistency, indirectness, impre-
cision and publication bias. Quality will then be graded as very low, low,
moderate or high.
The hierarchy of evidence can be stratied as follows:
Ia Systematic review or meta-
analysis of randomised controlled trials (RCT)
Ib At least one RCT
IIa At least one well- designed controlled study without randomisation
IIb At least one well designed quasi-
experimental study (e.g. cohort study)
III Well-
designed, non- experimental descriptive studies (e.g. case–control
and case series)
IV Expert opinion
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Clinical Cases in Critical Care
12
Recommendations are subsequently graded as follows:
A Based on hierarchy I
B Based on hierarchy II or extrapolated from hierarchy I
C Based on hierarchy II or extrapolated from hierarchy I or II
D Based in hierarchy IV or extrapolated from hierarchy I, II or III
A full discussion of evidence-
based medicine is beyond the scope of this
book. However, it is worth noting that it is possible to nd contradictory evi-
dence for almost anything in medicine! While is it important to keep up to date
and well apprised of current literature and recommended guidelines, every
patient is unique and may not t neatly into a management protocol. There
is no substitute for making a detailed clinical assessment. Armed with your
medical knowledge, your understanding of the patient’s unique set of problems
and an awareness of the available evidence, you can take an individualised
approach to managing each critical care patient.
Key resources are often quoted in this book. Review these sources for
yourself so that you can understand how to apply the evidence to your
own practice.
Further reading
The Faculty of Intensive Care Medicine and the Intensive Care Society publish
Guidelines for the Provision of Intensive Care Services. Version 2.1 was published in
2022. GPICS V2.1 is available online at www.cm.ac.uk and www.ics.ac.uk.
The King’s Fund publishes an especially useful overview document called Critical
Care Services in the English NHS. This is available online at www.kingsfund.org.uk.
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Clinical Cases in Critical Care, First Edition. Alice Myers and Theophilus Samuels.
© 2023 John Wiley & Sons Ltd. Published 2023 by John Wiley & Sons Ltd.
Intubation
of the Critically
Unwell Patient
2
T
he aim of this section is to provide an overview of the main issues to con-
sider when approaching intubation and initial ventilation in the critically
unwell patient. The following is not intended to be a comprehensive guideline–
rather, it reects the experiences of the authors. As always, clinical judgement
should be used to modify techniques and individualise management strategies.
There is no ‘one size ts all’ when it comes to critical care.
Why?
Airway protection– the patient is at risk of:
airway obstruction, e.g. swelling secondary to anaphylaxis
aspiration, e.g. due to reduced GCS
trauma to the airway, e.g. burns or penetrating laryngeal injury.
Gas exchange
Failure to oxygenate, e.g. pneumonia.
Failure to ventilate, e.g. bronchospasm.
Apnoea.
Exhaustion or weakness
Neuromuscular disorders, e.g. myasthenia gravis.
Fatigue, e.g. respiratory compensation for metabolic acidosis.
Facilitate management
Patients unable to comply with treatment may require sedation and
airway protection to facilitate management, e.g. a uraemic patient
may be encephalopathic and intolerant of vascular access and hemo-
filtration.
Patients requiring emergency bronchoscopy or isolation of one lung
(e.g. pulmonary abscess).
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Clinical Cases in Critical Care
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Why not?
There may be occasions where it is not in the patient’s best interests to intubate
them, e.g. they have previously refused intubation and intensive care admission,
or they have a terminal condition which means they would not survive intensive
care. Talk to the patient if you can, review the clinical notes and previous esca-
lation plans if available. Ask about Advance Decision documentation.
When?
Now
The patient is in extremis. There is usually time to preoxygenate as a
minimum (while assistants gather drugs and equipment).
If delay will lead to deterioration, the airway must be secured as a
matter of urgency.
Later
There is a risk of deterioration when electing to postpone intubation
once the decision has been made that it is required. Clinical judge-
ment must always be used to evaluate the risks and benefits.
Consider whether you have time to bring loved ones in to see the
patient before you intubate. It is not always possible or practical and
it should never delay emergency management. However, even a brief
moment can make an enormous difference to patients and their
relatives.
Reasons to delay intubation include the following:
Optimisation of clinical condition–if the patient is cardiovascularly
unstable, they may benet from uids or vasopressors and further mon-
itoring with an arterial line prior to induction.
Acquiring appropriate equipment and sta–for example, when a new-
born requires intubation and the most experienced person available has
limited paediatric experience. In this case, it may be safest to wait for
experienced help.
Transferring the patient to a more appropriate location–for example,
when a patient has deteriorated on a general medical ward but the safety
benets of intubating them in critical care outweigh the risks of delaying
intubation by the time it takes to transfer them there.
Where?
Remote location– sometimes there is no choice but to intubate in a
remote location. If the patient is unsafe to transfer, then they must be
stabilised in situ.
Make the environment as safe as possible by asking a trained assistant
to bring monitoring, drugs and equipment.
Position the patient as optimally as possible (may prove difficult in
the angiosuite or MRI scanner).
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Intubation of the Critically Unwell Patient
15
Ensure there is a good supply of oxygen (use cylinders in the absence
of piped oxygen).
Ask ward staff to assist or to minimise distractions.
Familiar environment, e.g. ICU, operating theatres or ED resuscitation–a
routine preintubation checklist is useful. It should not be assumed that
monitoring is attached and equipment is available.
Who?
Roles should be allocated within the team according to skills and experience
and this should be clearly communicated. Know who to call for additional help
and how to contact them. Verbalise the plan before commencing.
First and second intubator–usually the second person to attempt intu-
bation should have more airway management experience than the rst.
If a dicult airway is anticipated or repeated instrumentation is likely
to cause complications, then the most experienced person should make
the rst attempt.
Administering drugs–ideally, an experienced doctor with an under-
standing of the relevant pharmacology will take this role. Once induction
drugs are given, this team member should be ready to administer drugs
for blood pressure augmentation and possibly additional sedation.
Trained assistant–this team member assists the intubator by passing
equipment and administering cricoid pressure if requested.
Someone on the pulse–if invasive blood pressure monitoring is unavail-
able, any other health professional can be allocated this vital role. This
person palpates a central pulse (usually femoral) and informs the team
whether the pulse is feeling weaker or stronger, allowing the team
member administering the drugs to titrate vasopressors until invasive
arterial monitoring is established.
Runner –this team member can fetch equipment, gas cylinders,
emergency help, make telephone calls, etc.
How?
Minimising the time between loss of consciousness (administration of
induction agents) and securing the airway is crucial. Critically unwell patients
are often quick to desaturate, and oxygen saturations may be poor even despite
preoxygenation.
The classic rapid- sequence induction (RSI) technique involving thiopentone
and suxamethonium is now rarely used by intensivists due to the potential for
cardiac instability, the side- eects of suxamethonium, and the availability of
newer drugs. Many favour a modied RSI approach which may bear little resem-
blance to the classic technique aside from sharing an end goal of securing the
airway as quickly as possible. There are a multitude of ways to achieve this safely.
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Clinical Cases in Critical Care
16
Assessment
In patients who need to be emergently intubated, a full airway
assessment can be impractical. However, a basic assessment of the
airway by an experienced operator can be performed in only a few
seconds if needed.
A MACOCHA score 3 predicts difficult intubation and is the only
validated airway assessment tool in the critically ill (Table1).
Pre- emptive assessment of patients on admission to critical care may
help identify potentially difficult airways and allow appropriate strat-
egies to be devised.
Setting up
We recommend using the Dicult Airway Society’s DAS ICU Intubation
Guidelines preintubation checklist.
Monitoring–minimum standards include ECG, pulse oximetry, end-
tidal carbon dioxide monitoring and non- invasive blood pressure.
Consider establishing intra- arterial blood pressure monitoring prior
to induction in patients at risk of haemodynamic instability.
Intravenous access–ensure that reliable IV access (usually at least
20 G) is available for administration of medications. Additional IV
cannulae or central venous access are likely to be required once
the patient is anaesthetised. Ensure cannulae are secured as they
can easily be dislodged during positioning, especially if the patient
is sweating.
Positioning
Usually the optimal position is approximately 30° head up, helping
to reduce the risk of aspiration through passive regurgitation and
improving functional residual capacity (FRC). Use pillows to facilitate
the anatomic sniffing position.
Table 1: MACOCHA score used for airway assessment
in
critically ill patients. The score ranges from 0 (easy) to 12
(very dicult). A
score ≥ 3 predicts dicult intubation
in
critically ill patients.
Factors Points
Factors related to the patient
Mallampati class III or IV 5
Obstructive sleep Apnoea syndrome 2
Reduced mobility of Cervical spine 1
Limited mouth Opening <3 cm 1
Factors related to pathology
Coma 1
Severe Hypoxaemia (SpO
2
< 80%) 1
Factor related to operator
Non- Anaesthetist 1
Total 12
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Intubation of the Critically Unwell Patient
17
During a trauma call, the patient should be kept flat with manual
inline stabilisation of the cervical spine.
There are cases where a patient’s condition is improved in recumbent
position, e.g. platypnoea-
orthodeoxia syndrome due to atrial septal
defect or hepatopulmonary syndrome.
Oxygen
Preoxygenation aims to wash out alveolar nitrogen and replace it
with oxygen. It is achieved by applying 100% oxygen for either 3min-
utes or for eight maximal inspirations and expirations. This increases
oxygen in the FRC. While, in health, this technique can prolong the
time until desaturation occurs by up to approximately 8minutes, it
may buy only seconds in the critically unwell patient.
Preoxygenation can be achieved using a Waters breathing circuit
(Mapleson C) with a closely applied facemask. This has the added
benefit of allowing positive end-
expiratory pressure (PEEP) to be
applied using the adjustable pressure limiting (APL) valve.
When the facemask is continually applied after cessation of
breathing, apnoeic oxygenation can help maintain saturations. In
health, during apnoea, approximately 250 mL/min O
2
diffuses from
alveoli into capillaries, but only 10–20 mL/min of CO
2
diffuses back
into alveoli (although CO
2
production remains around 200 mL/min).
This deficit results in a pressure difference, creating the potential
for mass flow of gas from pharynx to alveoli. Movement of gases
during apnoeic oxygenation can also be aided by cardiac oscilla-
tions. Consider using high- flow nasal oxygen (HFNO) throughout,
particularly during intubation attempts when the facemask has
been removed.
Call for help–even the most experienced intensivist may appreciate
skilled back- up during intubation of the critically unwell patient.
Drugs–there is no set recipe. Intensivists usually develop their own
techniques, and most will adjust their approach for individual patients.
The following list is not exhaustive, and agents can be used in various
combinations:
Opioids – used as co- induction agents, opioids can obtund the
laryngeal response, reduce requirement for other sedative drugs,
promote cardiovascular stability and minimise changes in intracra-
nial pressure.
Fentanyl–around 100 times more potent than morphine. Rapid
onset. Duration of action is approximately 30 minutes.
Alfentanil–onset of action is three times faster than fentanyl, but
duration of action can be several hours.
Hypnotics
Propofol–frequently used in combination with an opioid for
induction of anaesthesia in elective surgical patients. Propofol
causes signicant cardiovascular depression and so the standard
dose should be reduced when the patient is unstable. Caution is
required as even small doses in critically unwell patients can cause
catastrophic hypotension.
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Clinical Cases in Critical Care
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Ketamine–causes direct sympathetic stimulation and,
in healthy patients, there may be a small transient dose-
dependent increase in blood pressure on administration. It is
often preferred by prehospital specialists for this reason. How-
ever, ketamine also acts as a direct negative inotrope so cau-
tion should be employed in critically unwell patients where
endogenous catecholamines may be deplete. In some cases,
administration can result in reduced cardiac output and even
myocardial ischaemia. Ketamine has bronchodilator properties
and is useful in the management of life-
threatening asthma.
Doses can be titrated when used in infusion for sedation, bron-
chodilation or analgesia. Complications include hallucinations
and raised intracranial pressure.
Thiopentone–this rapid and short- acting barbiturate has a pre-
dictable onset and rapid oset time. This made thiopentone integral
to the original RSI technique. The anticonvulsant properties make
it a useful option for induction of anaesthesia in cases of status
epilepticus. However, it should be used with caution in critically
unwell patients as it can result in signicant hypotension.
Alternative strategy–to preserve cardiovascular stability, some cli-
nicians avoid these hypnotic agents at induction of unstable critical
care patients in favour of combining a fast- acting benzodiazepine
with a high- dose, fast- acting opioid.
Neuromuscular blockers
Rocuronium–this non- depolarising muscle relaxant has now
largely replaced suxamethonium as part of modied RSI. It has
a rapid onset of action, approximately 45
seconds, when given at
a dose of 1–1.5
mg/kg. It has a long duration of action but can be
rapidly reversed using sugammadex, a modied gamma cyclodex-
trin which chelates rocuronium, thereby inactivating it. Rarely, it
can cause bronchospasm or anaphylaxis.
Suxamethonium–rarely used in critical care now due to its side-
eect prole, suxamethonium (succinylcholine) has a rapid onset
of action and short duration. It is given at a dose of 1–2 mg/kg. This
depolarising muscle relaxant can cause hyperkalaemia, leading to
life-
threatening arrhythmias and cardiac arrest.
Others
Midazolam–can be given in combination with other agents to
promote greater haemodynamic stability at induction. As a ben-
zodiazepine, it is particularly useful in patients with intractable
seizures. It induces anterograde amnesia.
Lidocaine–can be used at induction to blunt the airway responses
to laryngoscopy and endotracheal intubation. It also supplements
the anaesthetic eects of the induction agent.
Vasoactive drugs
Metaraminol and phenylephrine–both have alpha- 2 and minimal
beta- adrenergic activity so are given to treat hypotension. Both
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