This hot case may come in a variety of flavours, depending on the aetiology of "airway failure". LITFL suggest a list of pathologies which are typically seen in this hot case scenario:
- post-operative surgical patient
- resolved respiratory failure
- head and neck surgical patients
- intra-oral sepsis (Ludwig’s angina)
- upper airway burns
A suggested approach to the assessment for extubation, divorced from the pfuffery of exam technique, is discussed in greater detail elsewhere. The hot case candidate however will need to trudge wearily though the entire examination process in a more formal fashion.
The major goals of this hot case are:
- Establish whether the primary pathology has resolved
- Establish whether extubation is likely to be successful
- Establish the difficulty of reintubation
- Suggest strategies to improve extubation success if the patient is still not ready.
Previous hot cases with this sort of theme to them can be found below.
The standard introduction
Ask examiners about turning up the lights
The physical examination
The details of this section can be seen in the opposite column.
The obs and investigations
The Physical Examination in Brief Detail
Ask the examiners to sit the patient up
Ask the examiners about any language barriers
Ask examiners to lay the patient flat.
- The examiner will give you a history.
- Wash hands.
- Gown and glove.
- Ask, if relevant:
- "Can I turn on all the lights?"
- "Are there any movement restrictions? Can I sit them up, or roll them on their side?"
- "Is there a language barrier?"
- Introduce yourself: “Hi Mr or Mrs Bloggs, I’m Dr So-and-so. I’m going to examine you, to see whether you're ready to get that tube out.”
- Rhythm - AF?
- Rate - tachycardia?
- Morphology: QRS width, ST elevation?
- MAP and abnormal morphology of the arterial waveform
- CVP and abnormal morphology of the CVP waveform
- Ancillary waveforms eg. the PA catheter waveform
- Oxygen saturation measurement, and the quality of the waveform
- End-tidal CO2 waveform and level - is there bronchospasm?
A pacing box?
- Pacing mode
- Set rate
Sensitivity and pacing threshold may not be relevant.
As far as assessment for extubation goes, this is where the money is.
One can ask the examiners the following questions:
- How are we oxygenating this patient?
- How are we ventilating this patient?
One should then establish that the following preconditions for extubation are met:
- The mode of breathing is patient-triggered; eg. PSV
- FiO2 is reasonable: 40% or lower
- PEEP is reasonable: 5-8 cmH2O
One should also ask the examiners to perform some manoeuvres to determine how far this patient is from extubation/decannulation.
Unassisted tidal volume:
The VT with zero PEEP and zero pressure support
Vital capacity (VC):
The maximum inspired volume with zero PEEP and zero pressure support
Maxiumum inspiratory pressure (MIP):
This can be measured by changing the trigger to -15cm H2O. The patient's ability to trigger at such a low pressure demonstrates a reasonable amount of respiratory muscle power. One should adjust the negative pressure trigger until the patient is able to trigger a breath; that level then becomes the maximum inspiratory pressure (MIP)
One should ask to look at the pressure-volume loops.
One should also take particular note of the respiratory rate and the tidal volume, as these values can be used to calculate the rapid shallow breathing index: RSBI = RR/VT.
Thus, to use the Wikipedia example, a patient breathing at a rate of 25 with tidal volumes of 250ml has a RSBI of ( 25/0.25) = 100.
An RSBI less than 105 is generally considered an indication of a readyness to wean from ventilation.
- Unusual colour
There may be surgical drains (what is in them? How much of it?). Asking how much has been coming out may be relevant in a hot case which focuses on the diagnosis of a shock state.
The pleural catheters are also interesting. One should make a mental note of whether the ICCs are on free drainage or on suction. The content of these drains could be informative, especially if one notices blood or chyle.
A CVVHDF or SLEDD process may be in progress. The savvy candidate may wish to ask the following questions:
- Which modality is being used?
- What is the dose of dialysis?
- What is the rate of fluid removal?
- How is the circuit anticoagulated?
- How long has this filter lasted?
These questions may go unanswered.
This stage is critically important. The patient being prepared for extubation should be on minimal sedation, little cardiovascular support, and (duh) not paralysed.
One should observe the following features of an EVD:
- Set height
- Whether it is open or closed
- The CSF colour - eg. is it full of blood?
If an EVD is present, one should take careful note of the level of consciousness. Is this patient going to be awake enough to maintain their airway after extubation? Has ICP management been difficult?
The physical examination
Ideally, one should get the patient sitting up to 30-45°. This may not be possible. However, one should still ask for it.
Ideally, the patient should be exposed from the waist up. The candidate can then stand back and look for anything externally obvious:
- Skin colour, eg. jaundice or the discolouration of chronic renal failure
- Muscle wasting, obesity
- The evidence of trauma, wound dressings, etc
- The pattern of breathing (eg. whether there is a characteristic chest flail)
Performing the GCS should be the first step.
The level of consciousness then determines how you go about examining the rest of the patient. It is also one of the pre-conditions for extubation. The successul extubatee will be crisply awake, waving all four limbs enthusiastically.
A traditionalist, who is examining Mr Bloggs, would approach the GCS in the following manner:
- Grab hold of both of the patient's hands.
- "Mr Bloggs!" One pauses to observe for eye opening.
- "Can you squeeze my hands?"
- If hand squeezing and eye opening is not observed, one administers a painful nail bed stimulus to both hands, to observe the response to pain.
One has just performed a GCS assessment; one is still holding the hands.Now, time to look at them more closely.
Given that the case focuses on the airway, this part of the examination may be performed with slightly less emphasis than is usual.
- Assess whether the hands are warm or cold.
- Look at the nail signs.
- Look for muscle wasting.
- Feel the radial pulses.
Tone of the upper limbs
Move up from the hands. While you are still holding the hands, you can perform a sort of gross examination of tone by pronating and supinating the wrists, and by flexing and extending the elbows.
In the conscious patient, it may be possible to assess asterixis by asking the patient to hold both their arms up with the wrists dorsiflexed.
This gives you an idea about their proximal muscle strength, and helps identify hepatic encephalopathy or hypercapnea.
Examine the cubital fossa for
- Peripheral lines
- Evidence of multiple venepunctures
- Lymph nodes
- Brachial pulse
- The presence of an obvious AV fistula
- Inspect any central lines
- Look again at the CVP
Palpate the neck:
- Trachea: is it midline? Is there a new tracheostomy there?
- Thyroid gland
- Cervical lymph nodes
- Carotid pulse - one side at a time!
- Submandibular lymph nodes
- Pre- and post-auricular lymph nodes
A massive submandibular abscess which has not settled down even after drainage would be a deal-breaker.
If the patient is conscious and there is no concern regarding CNS injury, one may omit the higher cranial nerve examination.
The mouth, airway, and swallowing apparatus are all important parts of this assessment for extubation
The Yankeur sucker is used to probe the posterior pharynx, on both sides. A gag reaction should result from this.
This collectively tests CN X and IX.
While on the subject of CN X, one may test the cough reflex by suctioning the trachea.
This tests CN X.
This is also a convenient time to ask about the volume and character of the secretions.
The conscious patient is asked to protrude their tongue, and move it from side to side.
This tests CN XII.
The uvula deviates away from the lesion.
This tests CN X and IX.
The cuff leak, by its presence, is a reasonable predictor that post-extubation stridor will not occur. Its absence, however, is not a very strong predictor of stridor.
One should ask about the quantity and character of secretions.
While at the face, one should ask whether the NGT has been suctioned dry, and how long the feeds have been stopped for.
One puts both their hands on the chest to assess the symmetry of chest expansion.
One might wish to percuss the chest. If this is done in a slick fashion, it can be forgiven.
Changes in percussion resonance may be worth commenting on.
One may begin by auscultating the apices anteriorly. Then, one should auscultate as posteriorly as possible. The money is in the bases. If one discovers bilateral atelectasis or large effusions, the question of extubation may be solved.
The clever candidate will make a big show of palpating both the apex and the right sternal edge.
One should auscultate in the following sequence:
- Left sternal edge, lower
- Left sternal edge, upper
- Right sternal edge, lower
- Left sternal edge, upper
- Both carotids
The various clicks and murmurs one encounters are discussed elsewhere.
For this, one should ask to lay the patient flat.
- Take a moment to behold the abdomen. One may ask the examiners to look under any surgical dressings; one is likely to be denied this part of the examination (they will tell you the wound looks clean and dry).
- All quadrants should be palpated.
- Then, feel for the liver edge; observe respiratory excursion
- Then, feel for the spleen.
- Then, try to ballot the kidneys. Enquire about renal tenderness.
- This can double as a test for peritonism.
- If there is some suspicion of ascites, one may ask to roll the patient, so shifting dullness can be better appreciated. The examiners may not permit this test.
- One should spend a good length of time on this, if one suspects bowel obstruction or ileus.
The pelvic content would have been palpated during the abdominal examination.
The more important part of this examination is the groin.
At this stage, the patient should be re-draped - cover them from the waist up, and uncover their legs.
Observation and palpation of the pelvis:
- There may be a rash of thrush, or a groin haematoma, or an external fixation device.
- The posterior pelvis and sacrum should ideally be palpated for pitting oedema.
Examination of the lines
- One should take notice of anything going into or coming out of the femoral vessels.
- There may be a vascath, a PiCCO catheter or some sort of angiography sheath. These are important clues. Why did this patient get an angiogram? What is the PiCCO for?
Examination of the genitals and rectum
- A complete examination would call for the palpation of the testes, and a comment on their size. However, this may not be practical.
- One should take note of any sort of waste management devices, eg. rectal tube, SPC or IDC.
- One should definitely ask about performing a PR.
- If one is forbidden from performing the PR, one should ask about the following features:
- Anal sphincter tone
- Size and quality of the prostate
- Presence of melaena or hard stool
Once one is finished with the pelvis, one should cover it again, so that only the legs are sticking out.
One should ask to remove TEDs and compression stockings.
- One should observe whether the lower limbs are mottled, and whether they are of the same size (assymetrical swelling leads one to suspect lymphoedema or DVT)
- One should palpate the larger muscles. Muscle wasting - especially of the quads- is an important feature of malnutrition. Additionally, one gets to appreciate the temperature difference between the limbs, which could be important in the assessment of peripheral vascular disease.
- Pitting oedema should be palpated.
Leg muscle tone
The best way to test muscle tone is by holding the knee. Roll the knee gently to distract the patient; then try to lift it off the bed. In the presence of increased tone, the leg will remain straight and the whole thing will lift up; with normal or decreased tone, only the knee will bend
In the conscious patient, one might be able to assess whether a gentle calf squeeze produces the characteristic pain which suggests a DVT may be present.
This brings one to the feet, and to the beginning of the neurological examination.
The feet would have already been palpated to assess their temperature, and to look for pitting oedema.
Observation of the feet
One should look specifically for changes suggestive of chronic diabetic foot disease, or chronically poor vascular supply.
Palpation of the feet
This should consist of palpating the dorsalis pedis and posterior tibial pulse.
One should test the Babinsky bilaterally.
One should attempt to assess clonus in both feet.
The neurological examination of this patient is mainly to establish whether there will be sufficient muscle strength in the proximal groups to assist the muscles of respiration.
Power of the muscle groups may be tested in the following sequence:
- Ankle dorsi and plantarflexion
- Knee flexion and extension
- Hip flexion, extension, adduction and abduction.
- Hand grip
- Wrist dorsiflexion/palmarflexion
- Elbow flexion/extension
- Shoulder adduction / abduction
One should ask to perform direct or videolaryngoscopy.
When the examiners refuse, one should ask about the previous grade of intubation.
Ask to see the obs chart. If it is not allowed, ask for the following:
- Trends of blood pressure and heart rate
- Drain output
- Urine output
One may also wish do demonstrate an interest in the trends of any sort of advanced haemodynamic monitoring, eg. cardiac index as measured by PAC or PiCCO
One needs to show an interest in the following labs:
- Routine bloods
- Culture results
- Case-specific bloods, eg. CK, troponin, LFTs, pancreatic enzymes, inflammatory markers...
One should always ask for the following:
You sometimes want to see the following:
- CSF analysis
- CT or MRI results
Case presentation and discussion:
"Mr Bloggs is [ready/not ready] for extubation."
"I have come to this conclusion on the basis of the following findings: [insert clinical findings here]"
"I would like to perform further investigations before I reach a firm decision: [insert appropriate investigations]"
"I would like to optimise my chances of extubation success by using the following strategies [sedation weaning, diuresis, physiotherapy, dexamethasone]"
"I would also like to prepare for reintubation in the event of unexpected extubation failure."