U2 O1 - Monitoring the critical patient Flashcards
Why are the three major body systems the most important at assessing in an emergency when failure of other body systems can also lead to death?
The three body systems that should be assessed initially in the critically ill/ trauma
patient are the neurological, cardiovascular and respiratory systems. Some sources
will add in the renal system which is, of course, also important. However, with
emergency and critical care cases, the major body systems that are assessed are
those that that can lead to death within minutes and not hours if not functioning.
Why is it important to monitor trends?
Monitoring of trends, especially, is highly effective at identifying the stable versus the unstable patient; and the improving versus the deteriorating
patient. Monitoring trends involves comparing variables over a timescale e.g. respiratory rate, pulse rate, pulse strength, serum lactate etc. (Bradbrook, 2013). If a patient admitted for observation following a road traffic accident, became increasingly dull, with an increasing heart rate, increasing respiratory rate and
weakening/ absent peripheral pulses, the trends would be of concern. This patient does not have stable cardiovascular, respiratory and neurological parameters- there could be an undetected problem e.g. internal haemorrhage. It should be noted that
following a traumatic incident some abnormalities are not always apparent on admission of the patient to the hospital. For example, a patient could develop pulmonary contusions over a period of hours following blunt trauma to the chest.
Ongoing diligent monitoring is vital for the emergency presentation and will often be the task of the registered veterinary nurse.
What are the key principles to guide the care of the small animal ICU patient?
Key principles to guide the care of the small animal
ICU patient.
• Treat the most life‐threatening problem first
• Treat the patient, not the numbers
• Anticipate the worst and be ready for it
• Provide the right treatment, at the right time, in the right amount
• Examine the cause of the problem and the effect on the patient
• Weigh the pros and cons of every drug and procedure
• There is not a drug for every problem – less is best
• If it has not been written down, it has not been done
• Never ignore your gut feeling
• Things are done in the order of importance
What is the aim of Kirbys rule of 20?
Problems within the major organ systems should be anticipated in advance, with appropriate diagnostic, therapeutic, and monitoring efforts employed early, rather than waiting for a problem to surface and reacting to it. The Rule of 20 was developed to assist the critical care team in thoughtfully and carefully assessing these patients.
What are kirbys rule of 20 parameters?
Fluid balance Blood pressure Albumin, COP Glucose Electrolytes Acid – base Oxygenation/ventilation Coagulation Red blood cell status Heart rate, rhythm, contractility Neurological status Urinary tract status WBC, Immune status GI tract status Nutritional status Drug dosing, metabolism Body temperature Pain control Wound and bandage care Nursing care, TLC
The Rule of 20. Each parameter should be assessed regularly in any critically ill dog or cat. The order of importance will vary between individual patients. COP, colloidal osmotic pressure; GI, gastrointestinal,
TLC, tender loving care; WBC, white blood cell.
What history should be ascertained from the owner of a critically ill patient?
Signalment Alert for age, breed and intact reproductive
tract related disorders
Presenting complaint Noted by staff at time of presentation and recorded. Best not to start history with this inquiry in order to control the historical
sequence of the problem
Last normal Inquire when patient was last absolutely
normal, may be abnormal prior to presenting
complaint. Differentiates peracute, acute,
chronic, and acute‐on‐chronic problems
Progression Outline of sequence of changes occurring in the patient from the time of “Last normal”
until the present day
Characterization of problems
Identified problems are characterized (such as volume, rate, consistency, color, sound, intensity, duration). Individual problems in the Rule of 20 are discussed in individual chapters
Systems review Report on problems or systems not discussed related to the current problems and
progression. Examples include: vomiting, diarrhea, coughing, sneezing, nasal or ocular discharge, seizures, fainting, weakness, water
intake, urination frequency and effort, urine color, stool consistency
Past medical history Vaccination, heartworm, and parasite control are listed. Any blood transfusions, problems with anesthesia or sedation are reported. Past medical problems and laboratory results of
concern
Medications List prescribed, over the counter and
supplements given to the animal. Medications
taken by the owner may be important if patient exposure is possible Exposure to toxins or infectious disease Inquire about the patient environment
including outdoor habits, ill animals or people,
groups of animals, new products or people
and other lifestyle habits
Nutrition Inquire about type, quantity, and brand of
food, feeding routine, appetite, access to
water, weight gain or loss
What should be determined when assessing the cardiovascular system?
When examining the cardiovascular system, the focus should be upon determining if there is adequate tissue perfusion.
What should be assessed when checking the cardiovascular system?
The patient’s mentation should be judged as
appropriate or not - decreased cerebral perfusion will result in behaviour changes
e.g. the patient is obtunded or stuporous etc. Mucous membranes should be assessed regularly to ensure that they are a normal, pink colour and the capillary
refill time (CRT) is normal (1-2 seconds). Both an abnormally slow and an abnormally rapid CRT would be a significant finding.
Central and peripheral pulses should be regularly palpated to ensure that they are
strong and synchronous. Any change from normal should prompt further investigation of the cardiovascular system e.g. in a dog a palpable femoral pulse but absent dorsal pedal pulse would be a significant finding that should prompt thorough
re-evaluation of the cardiovascular system, including arterial blood pressure monitoring
Auscultation of the heart is important to detect the heart rate and rhythm. Additional
finding such as muffled or abnormal heart sounds e.g. murmurs should be recorded.
What does an ECG monitor?
ECG uses the electrical impulses generated by the cardiac conduction system to create a tracing which can be used for monitoring both the heart rate and rhythm.The ECG monitors and transmits electrical activity at the body surface to create the ECG trace.
What does an ECG not assess?
It does not, however, give any indication of heart function i.e. the ability of the
myocardium to contract nor if the patient is in heart failure.
What common ECG disturbances can be seen in critically ill patients?
Common ECG disturbances, in critically ill patients, include sinus tachycardia, sinus bradycardia, accelerated idioventricular (pertaining to the cardiac ventricle alone) rhythm, premature ventricular complexes and ventricular tachycardia. ECG
manifestations of hyperkalaemia (spiked T waves, prolonged PR interval, loss of P waves and widening of the QRS) may occur in patients with urinary tract dysfunction resulting in decreased urine output e.g. bladder rupture or urethral obstruction
Why is it important to perform an ECG on an animal with hyperkalemia?
Hyperkalaemia can cause a fatal cardiac arrythmia so prompt recognition of ECG
changes suggestive of it are crucial.
What factors depend on whether cardiac dysrhythmias require treatment?
The need to treat and choice of treatment for cardiac dysrhythmias is dependent on various factors- heart rate, clinical signs, evidence of perfusion abnormalities, underlying cause and presence of specific ECG changes e.g. multiform complexes or the ‘R on T’ phenomenon.
How do you determine if a patient has an accelerated idioventricular rhythm on an ECG?
It is likely that a dog has an accelerated idioventricular rhythm if there are four or more consecutive ventricular ectopic beats/ ventricular premature contraction (VPCs) but the heart rate is ≤ ~ 140 beats per minute.
Does an accelerated idioventricular rhythm on an ECG require treatment?
In the absence of perfusion abnormalities attributed to this rhythm, definitive treatment with an antidysrhythmic is not warranted as the treatment may lead to serious side-effects. Maintenance of
euvolaemia (normal blood volume), adequate oxygenation, and normal acid-base and electrolyte status is indicated.
Dysrhythmias resulting in decreased perfusion, as evidenced by clinical signs (e.g. depression, syncope, poor pulse quality, pale mucous membranes, cool extremities, prolonged CRT) or objective means (hypotension, hyperlactataemia) will required
additional treatment following correction of hypovolaemia and hypoxaemia.
What is blood pressure a marker for?
Blood pressure can be used as a surrogate marker of blood flow to tissues e.g. low blood pressure would indicate decreased perfusion.
Why might a patient with decreased perfusion have a normal blood pressure reading?
Blood pressure can be used as a surrogate marker of blood flow to tissues e.g. low blood pressure would indicate decreased perfusion. However, in some patients, intense peripheral vasoconstriction because of compensatory mechanisms in response to e.g. blood loss may result in an ‘adequate’ blood pressure reading (Thomovsky, 2013). This patient would, however, have minimal perfusion/ blood flow to the periphery despite a normal blood pressure reading- thus it is important to record blood pressure alongside other observations for it to be meaningful. Different vascular beds in the body may have differing blood flow (perfusion) at the same blood pressure.
What is the normal systolic blood pressure for a dog?
Systolic pressures of ~110-160 mmHg
What is the normal diastolic blood pressure for a dog?
Diastolic pressures of~ 55-110 mmHg
What is the normal mean blood pressure for a dog?
Mean pressure of ~100 mmHg
What is the normal systolic blood pressure for a cat?
Systolic pressures of ~120-170 mmHg
What is the normal diastolic blood pressure for a cat?
Diastolic pressure of ~70-120mmHg
What is the normal mean blood pressure for a cat?
Mean pressure of ~ 135 mmHg
When does hypertension become a concern?
Hypertension becomes a concern when systolic pressure increases above 170 mmHg, or diastolic pressure is greater than 110 mmHg.
Following trauma what would be a concern with blood pressure and heart rate which could indicate intracranial pressure?
Following head trauma, a systolic blood pressure recording of greater than 140 mmHg (with a heart rate of less than 100 beats per minute) could be an
indication of increased intracranial pressure (ICP).
What detrimental effects could hypertension cause in the body?
Hypertension can cause end-organ injury including retinal detachment and
glomerular damage.
What could elevations in arterial blood pressure be a result of?
Elevations in arterial blood pressure result from pain, fear, raised intracranial pressure, metabolic and endocrine diseases, renal and cardiac disease, and
various medications
At what low level blood pressure should be addressed?
Systolic blood pressure of less than 100 mmHg or mean arterial pressure of less than 65 mmHg should be addressed. The lower the value the more
serious the condition.
In the trauma patient what can low blood pressure be a result of?
In the trauma patient, low blood pressure can result from reduced cardiac output secondary to hypovolaemia, myocardial failure and dysrhythmias
What two categories can arterial be measured by?
Options include direct arterial blood pressure monitoring, which requires the insertion
of a catheter into an artery; or more commonly, indirect blood pressure monitoring.
What does indirect blood pressure monitoring involve?
It relies on the inflation of a cuff to occlude an artery and therefore temporarily prevent blood flow in it; followed by measurement of the pressure at which blood flow returns when the cuff is gradually deflated. The inflatable cuff is attached to a sphygmomanometer or, directly, to an oscillometric blood pressure monitoring
system.
What position should the patient be in to get the most accurate reading for direct blood pressure monitoring?
The patient should be kept still, in lateral recumbency, to get the most accurate readings with the cuff level with the right atrium
What are the benefits of indirect blood pressure monitoring?
Non-invasive blood pressure monitoring is readily available, relatively cheap and
easy to use
How do you select the correct cuff size for patient for indirect blood pressure monitoring?
Appropriate cuff size selection is important; the cuff should be 40% of the circumference of the limb for dogs; the cuff width should be 30- 40% of the width of
the limb in cats
How might results be inaccurate if the cuff size for indirect blood pressure monitoring is too large?
Cuffs that are too large will give falsely low pressure readings.
How might results be inaccurate if the cuff size for indirect blood pressure monitoring is too small?
Cuffs that are too small will generate falsely high pressure readings.
How does a doppler measure blood pressure?
This uses ultrasound waves to detect arterial blood flow and turns it into an audible signal. Earphones should be used to avoid the noise of the ultrasound causing increased patient stress
A 10-MHz ultrasound probe is placed over an artery distal to the cuff. The Doppler
sounds become audible when pressure in the cuff is less than pressure in the artery.
What type of blood pressure does a doppler measure?
Doppler ultrasonographic determination of blood pressure is thought to provide a systolic blood pressure measurement and can be used in all small animals. In cats it is thought to be closer to the mean arterial blood pressure.
What common arteries are used for doppler blood pressure?
Common arteries used for Doppler blood pressure measurement include the dorsal metatarsal, the plantar metatarsal, the palmar metacarpal, the ulnar and the coccygeal arteries.
How does oscillometric blood pressure measurement work?
These monitors utilise vibrations, conducted to adjacent tissues by the return of
blood flow to the occluded artery, to measure mean arterial blood pressure. The
machine uses algorithms to calculate systolic and diastolic blood pressure from the
mean arterial blood pressure. Oscillometry is often incorporated into multi-parameter
patient monitors where the blood pressure is recorded and the pulse is shown on the
screen. The cuff must fit snugly so that the
oscillometric blood pressure monitor is able to detect tissue vibrations.
What is the main advantage to using oscillometric blood pressure monitoring?
One advantage of oscillometry is that is automated – this means there is less
reliance on user technique being correct and it can be less stressful for the patient.
What areas can oscillometric cuffs be placed?
The oscillometry cuff can be placed on the forelimb, hindlimb or the tail - midantebrachium and the metatarsus. Bradbrook (2013) reports that using the
metatarsus is more reliable than the metacarpus.
What could cause oscillometric readings to be unreliable?
The accuracy of the readings is limited in patients
with peripheral vasoconstriction, patients who are moving/ shivering or patients with dysrhythmias. The cuff may also not fit snugly enough in very hairy patients to obtain accurate readings.
What is considered to be gold standard for the determination of blood pressure in veterinary patients?
Direct arterial blood pressure (invasive) measurement is considered the gold standard for the determination of blood pressure in human and veterinary patients
What information does direct arterial blood pressure invasive give you?
It enables continuous reading of systolic, diastolic and
mean arterial blood pressure, giving beat by beat information and enabling rapid
response to changes. This technique is mainly used for ECC patients requiring
intensive care
When is invasive direct arterial blood pressure indicated?
it is mainly ‘indicated in patients with severe haemodynamic abnormalities to assess the response to therapy and to monitor for any deterioration’
When is the placement of invasive arterial blood pressure contraindicated?
It is invasive and there are several potential
complications to be aware of. Direct arterial blood pressure monitoring is not indicated in healthy patients that are ambulatory due to the associated risks of the
procedure. There is a greater likelihood that a mobile patient could disconnect the line or remove the catheter, causing arterial haemorrhage
Arterial catheter placement is absolutely contraindicated in a patient with a
coagulopathy, or an injury/ wound on the limb of the proposed placement site; it is relatively contraindicated in a patient that is ambulatory or a patient that will not be monitored continually on a 1:1 basis due to the risk of serious blood loss.
Where is the catheter placed for direct arterial blood pressure measurement?
Direct arterial blood pressure measurement involves catheterisation of a peripheral artery. Whilst possible in cats, it is more technically demanding
If necessary, a cut down to the
dorsal metatarsal or femoral artery can be performed.
Describe the technique for placement of an arterial catheter for direct blood pressure measurement?
The arterial catheter is connected to a pressure transducer via a fluid-filled tubing system. Non-compliant tubing must be used to avoid dampening of the pressure signal
• The pressure transducer converts the mechanical signals induced by pulsatile
arterial pressure to electrical signals that are then recorded, quantitated and
displayed graphically.
• Most commercially available arterial blood pressure recording systems
provide a continuous delivery of a heparinised, isotonic solution, at 1-3mL/hr,
to prevent catheter occlusion.
• A catheter is most often placed in the dorsal metatarsal artery - although the
femoral, auricular, plantar metatarsal and plantar metacarpal arteries may
also be used. Some anaesthetists use the coccygeal artery in cats
(Bradbrook, 2013).
• Local anaesthetic cream (EMLA™) should be used in the conscious patient
as this can be a painful procedure
• The site should be aseptically prepared and the patient adequately restrained.
• After palpation of the metatarsal pulse, the catheter should be advanced through the skin and directed towards the artery. The angle is steeper than
when placing a peripheral venous catheter- insertion into the artery is normally achieved at an angle up to 45 degrees. Once the artery is punctured
with the catheter stylet, a flash of arterial blood will be seen in the hub of the stylet and it should fill readily due to arterial blood pressure. The entire
catheter and stylet should be advanced forward 1-2 mm to allow the distal tip of the catheter to penetrate the vessel lumen. At this point, the angle of the catheter to the artery is decreased and the catheter advanced off the stylet into the artery.
• Once the catheter is in the artery, it should be connected to the pressure monitoring system or a length of low compliance IV extension tubing, flushed
with saline, and occluded with an injection cap. The arterial catheter is then taped very securely and labelled as “arterial” so that it is not mistakenly used
for the administration of fluids or medications.
What type of blood pressure monitoring is the most reliable in hypoperfused patient and patients with peripheral vasoconstriction?
Direct arterial blood pressure measurement is reliable in hypoperfused patients and
patients with peripheral vasoconstriction, though placing an arterial catheter during
these situations is more technically challenging.
What are some do’s and don’t’s for using an arterial blood pressure catheter?
Direct arterial blood pressure measurement is reliable in hypoperfused patients and
patients with peripheral vasoconstriction, though placing an arterial catheter during
these situations is more technically challenging.
An arterial catheter may be used to obtain blood for arterial blood gas determination
- a strict aseptic technique must be performed.
What does central venous pressure represent?
CVP represents the hydrostatic pressure in the intrathoracic vena cava and provides
an assessment of right-sided preload. The CVP is equal to the pressure in the right atrium which, in turn, is equal to the pressure in the right ventricle as the tricuspid valve opens (e.g. end-diastolic pressure). CVP is therefore, an indirect reflection of intravascular volume- the pressure decreases as the blood volume decreases and vice versus
