The usual questions for this hot case are "why is this patient having such trouble weaning from ventilation", and "what strategies might accelerate this process".
Problems with weaning might be caused by:
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.
Sit the patient back up again
During this period, look around the room. One might find various cubicle cues to suggest that the patient has taken up permanent residence in the ICU. Are there family pictures and religious paraphernalia hanging everywhere, is the patient's favourite blanky from home draped all around them?
A pacing box?
Sensitivity and pacing threshold may not be relevant.
One can ask the examiners the following questions:
One should ask about the following parameters:
One should ask to look at the pressure-volume loops.
NAVA may be in use. One should look at the Edi and the NAVA assist level, to track the progress of the patient's weaning. The use of this srategy may point the candidate in the direction of neurological testing; this patient's weaning process may have been frustrated by muscle weakness.
Ask about the trigger settings.
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.
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)
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:
These questions may go unanswered.
This stage is critically important. The drug and fluid infusions which are currently in progress give a clue as to what problem is currently being addressed. One should not neglect the labelled bags; the choice of antibiotics gives one some idea of where the source of sepsis is thought to be.
A specific interesting infusion to look for would be IV immunoglobulin, which might suggest that some sort of autoimmune disease is playing havoc with the myelin or the neuromuscular junction.
Lastly, there may not be any infusions! The patient's long stay in ICU may be purely related to the ventilation problem.
The presence of an EVD may alert you to the idea that central control of respiration is somehow impaired. This opens new topics for discussion at the end, and also mandates a thorough neurological examination.
One should observe the following features of an EVD:
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:
Performing the GCS should be the first step, unless you notice that a neuromuscular junction blocker is among the infusions. The level of consciousness then determines how you go about examining the rest of the patient.
A traditionalist, who is examining Mr Bloggs, would approach the GCS in the following manner:
One has just performed a GCS assessment; one is still holding the hands.
Now, time to look at them more closely.
First, one should spent a second assessing whether they are warm or cold.
Then, one can focus on the nails. Nail signs are numerous and deserve their own page.
In brief, the nail signs one could look for are as follows:
Vertical nail ridges
Horisontal nail ridges
Done with the nails, one may want to briefly consider (and maybe even comment upon) the presence of any sort of characteristic deformities, eg. assymetrical wasting of the small muscles, or the joint changes of rheumatoid arthritis.
Next comes the pulse. While one still has both of the patient's hands, one ought to try to compare the radial pulses. It would be worthwhile to look up at the arterial line trace at this stage; abnormalities such as the widened pulse pressure of aortic regurgitation may not have been noticed until this stage.
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 also doubles as a good screening test for muscle power. if the patient is unable to raise their arms, there may be a serious muscle weakness, and one should be particularly interested in the neurological examination.
Examine the cubital fossa for
One should then palpate the axillary lymph nodes.
Palpate the neck:
Generally speaking, one cannot avoid a detailed examination of the cranial nerves in this hot case, because intracranial and neuropathic causes of slow weaning are important, and one would not wish to miss a disabling CNS disease in their assessment.
This section can be divided into three broad groups:
|The paralysed patient||The unconscious patient||The awake patient|
A Snellen chart is ideal, but probably will not be available.
The extubated patient should be able to read the time on the clock in the room.
One performs this test with each eye individually.
This tests CN II.
Ask the examiners to dim the room lights.
Open both eyes. Each eye is exposed to light. The opposite pupil should constrict consensually.
This tests CN II (afferent) and CN III (efferent).
The cornea (not the sclera) is touched lightly with a moistened corner of a piece of gauze.
A normal reflex is to blink.
This tests CN V (afferent) and CN VII (efferent)
The conscious patient will be able to follow the tip of the candidate's finger.
The pattern of movements should be tracing the six cardinal points: superior left, inferior left, superior center, inferior center, superior right, inferior right.
This tests CNs III, IV and VI.
Typically, this is performed by putting some pressure on the superior orbital notch.
The patient should either open their eyes or localise.
This tests CN V.
The conscious patient will be able to perform a series of grimaces to assess the bilateral motor control of facial muscles:
In the comatose patient, as the head is moved from left to right, the eyes should move in the opposite direction. A fixed unchanging gaze is a negative test; the reflex is not working.
This tests CNs III, IV, VI, and most importantly VIII.
Cold water is funneled into the patient's ear. A positive reflex consists of the eyes turning towards the chilled ear. This is a more potent stimulus for CN VIII than the oculocephalic reflex.
Now that one has finished with the upper cranial nerves, one can move on to the mouth, airway, and swallowing apparatus.
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 conscious patient is asked to shrug their shoulders against resistance.
This tests CN XI.
Thus, the whole process should look like this:
During the cranial nerve examination, one will inevitably end up tripping over the endotracheal tube. One should note whether there is anything unusual there; for instance, is there a dual-lumen tube, or a bronchial blocker?
With the ETT, one should ask how long it has been in situ.
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. One does not want to miss the atelectatic bases, or the presence of large pleural effusions.
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:
The various clicks and murmurs one encounters are discussed elsewhere.
If the patient has massive cardiomegaly and severe CCF, one needs to detect this.
For this, one should ask to lay the patient flat.
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:
Examination of the lines
Examination of the genitals and rectum
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.
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.
Now is the time to properly start the neurological examination of this patient. This should be performed thoroughly, as it might reveal some sort of muscle weakness, a juicy topic fo discussion later.
Power of the muscle groups may be tested in the following sequence:
The patient has spent most of this time flat and supine. Time to sit them back up again.
Power of the upper muscle groups may be tested in the following sequence:
Now that one is back to the upper limb, one may as well start their reflex tests there.
The reflexes may be tested in the following order:
After testing the ankle jerk reflex, one is again back to the feet.
At this stage, with a conscious patient, one may wish to test light touch sensation.
The following order (with corresponding dermatomes) is suggested:
Ask to see the obs chart. If it is not allowed, ask for the following:
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:
One should always ask for the following:
"Mr Bloggs' difficuly in weaning from the ventilator is due to [insert clever diagnosis here]."
"I have come to this conclusion on the basis of the following findings: [insert clinical findings here]"
"I would like to confirm my diagnosis with the following investigations: [insert appropriate investigations]"
"The current management issues are as follows: [a brief list of management priorities]"
"I would approach the management of these issues in the following manner: [list of management strategies; it helps to organise this into an A,B,C,D,E approach if one has a complex multisystem problem to manage]"
"Overall, my weaning strategy will consist of [insert sensible strategy]".
”Mr Bloggs' difficult ventilator weaning is likely multifactorial."
"Factors which may be contributing include [primary respiratory failure, weakness, delirium, decreased level of consciousness]"
"I have identified clinical findings which support this hypothesis: namely, [insert list of findings]."
"The possible aetiologies responsible for this could include [list of differentials]"
"In order to discriminate between these differentials, I would like to perform the following investigations: [list of investigations]"
"I also note the following organ failures: [list organ problems]."
"Given the complex nature of this illness, I would like to enlist the help of the following specialties [insert list of consults], for whom I will have the following specific requests/questions: [what questions will you ask these specialist teams]"
"Otherwise, my weaning strategy will consist of [insert sensible strategy]".