2. Introduction
In a critically ill patient, the history is often incomplete, physical
examinations are frequently inconclusive and the signs on which the clinical
diagnosis depend often disappear when the patient approaches death making
the diagnosis difficult to establish. So, management of these patients in general
wards becomes difficult.
An Intensive Care Unit (ICU) is fully equipped with monitoring and
technical facilities and patient can receive continuous expert nursing care and
the constant attention of appropriately trained medical staffs, which is not
possible in general wards.
Objectives while managing these
patients:
To sustain life.
To prevent, reverse or minimize damage to vital organs.
3. Whom to label as Critically Ill?
The identification of the at risk patient or those patient who could
benefit from intensive care treatment is largely based on scoring
systems. The most frequently used scoring system is APACHE II (Acute
Physiology Assessment and Chronic Health Evaluation), which is based
on evaluation of 12 physiological variables which are altered in response
to stress or disease process. The physiological parameters are:
1. Temperature - core 10. Hematocrit.
2. Mean arterial pressure 11. White blood cell count.
3. Heart rate 12. Glasgow coma score.
4. Respiratory rate.
5. Oxygenation
6. Arterial pH
7. Serum sodium
8. Serum potassium
9. Serum creatinine
4. Monitoring of critically ill
Monitoring of physiological responses to stress or disease not only
allows the assessment of the physiological reserve of the patient but
will also give a baseline against which the effectiveness of any applied
treatment can be judged. No single parameter is significant. Changing
parameters of trends are more significant.
Monitoring of Cardiovascular System:
1. ECG:
Gives information about rate and rhythm changes, but is not useful to
monitor ischaemic changes.
Modified form – lead CM5 can be used to detect both ischaemic
changes and arrhythmias.
2. Blood pressure:
May be monitored intermittently with sphygmomanometer.
Continuous monitoring with line placed in radial artery is preferable.
5. 3. Central Venous Pressure (CVP):
Monitored by placing a catheter in either subclavian or internal jugular
vein.
Useful means of assessing the circulating volume and determining the
appropriate rate of intravenous fluid replacement.
4. Pulmonary Artery Occlusion Pressure (PAOP):
More beneficial than CVP in critically ill patient, right ventricular
dysfunction and pulmonary vascular disease.
Measures the left ventricular end diastolic pressure.
5. Cardiac Output:
Most commonly measured by thermodilution technique.
Cold 5% Dextrose is injected in central vein and after admixture with
total venous return in right ventricle, temperature of blood is measured
in pulmonary artery with a thermistor.
6. Fluid balance:
By maintaining strict input/output chart
7. 7. Temperature:
Gradient between core and peripheral temperature is a better
indicator of peripheral perfusion.
8. Haematocrit and Haemoglobin concentration:
Hct of 35% and Hb% of 12-14 gm/dl is thought to be optimal
because reduction of viscosity of blood is thought to enhance tissue
perfusion.
9. Gastric tonometry:
Indirect means to measure gastric mucosal intracellular pH.
PCO2 of gastric content is estimated using a silicon balloon attached
to the tip of nasogastic tube. (Since PCO2 of luminal content is
thought to equilibriate with gastric mucosal intracellular PCO2).
Localised intracellular acidosis may be due to:
o Decreased oxygen supply to these cells.
o Impaired oxygen utilization by these cells.
May be the earliest index of impaired core tissue perfusion with
oliguria and arterial acidaemia developing later on.
8. Monitoring of Respiratory System:
1. Oxygen saturation by Pulse Oximetry:
Probe is attached to finger or ear lobule.
Spectrophotometric analysis.
Normal >97%.
Not effective when peripheral perfusion is reduced.
Cannot differentiate Carboxyhaemoglobin form Oxyhaemoglobin.
2. Arterial blood gas analysis:
Especially beneficial in ventilated patient.
Helps to adjust inspired oxygen and minute volume to achieve a desired
PaO2 an PaCO2 respectively.
Also useful to monitor acid-base balance.
9. Monitoring of Renal System:
1. Urinary flow:
Sensitive measure of renal perfusion.
Measured by simply placing a self retaining catheter.
Should not fall below 0.5ml/kg body weight/hour.
2. Serum Electrolytes, Urea and Creatinine
Monitoring of Central Nervous System:
1. Intracranial pressure (ICP):
ü Normal <10mm of Hg.
ü Indicated in patients with head injury, subarachnoid haemorrhage, hepatic
encephalopathy, brain tumours and encephalitis.
ü Made by placing a device within a cranial vault by making a small burr
hole in parietal or frontal areas of non dominant hemisphere.
ü Cerebral oedema and haemorrhage causes a rapid rise in ICP.
ü ICP above 20-25 mm of Hg warrants immediate correction.
10. 2. Cerebral function monitor (CFM):
Compact form or EEG where unwanted frequencies are filtered.
Indicated during carotid artery surgery and those who are likely to
develop convulsions.
1. Assessment of Clotting function:
For those who develop haemostatic failure and acquired coagulopathies.
Prothrombin time, Activated Partial Thromboplastin Time (APTT),
Fibrin Degradation Products (FDP) or D-dimer.
Conclusion:
Different patients respond to a similar insult in different ways and have
different physiological reserves. Assessment of physiological status is
important in allowing these differences to be appreciated. In addition,
many of the treatment options we use in the critically ill patient require
some form of physiological monitoring for us to gauge their
effectiveness, which is the main aim of meticulous monitoring of these
paitents.
Monitoring of Haematological parameters:
11. References:
1. Davidson’s Principles and Practice of
Medicine – 18th Edition.
2. Clinical Medicine by Parveen Kumar &
Michael Clark – 3rd Edition.
3. Website -
http://www.rcsed.ac.uk/journal/vol44_6/446
0010.htm
