Monitoring in anaesthesia involves using devices and instruments to continuously track physiological parameters like respiration, oxygenation, circulation, and temperature. This allows the anesthetist to maintain patient stability and safety during surgery. Standard monitoring includes evaluating ventilation, oxygenation, and circulation through non-invasive means like pulse oximetry, capnography, electrocardiography, and blood pressure monitoring. Additional invasive monitors may be used for complex surgeries or high-risk patients. Continuous monitoring is essential for detecting any problems and making timely interventions.

1. MONITORING IN
ANAESTHESIA
MUHAMMED AMIN BADAMOSI

2. outline
• Introduction
• Goal of monitoring
• Standard for basic anaesthesia
• Monitoring devices
• Monitors for ventilation
• Monitors for oxygenation
• Temperature monitoring

3. Introduction
• Monitoring in anaesthesia is the process by which vigilance over
physiological parameters is maintained with the help of special
instruments and devices.
• It provides information which anaesthetist use to provide safe
anaesthesia for a patient undergoing surgery.

4. Goal of Monitoring
• Physiological stability
• Safety perioperatively
• Early identification of problem for early correction

5. ASA Standard for basic anesthesia monitoring
• Qualified and experienced personnel should be present throughout
anesthesia
• Evaluation of the patient’s
• Respiratory (ventilation, oxygenation),
• circulation
• temperature

6. Anesthetist presence
• Care for patient continuously
• close observation of the patient and the events in the operating
theatre
• Extensive monitoring of the anesthetic machine and equipment
• Keeping records of measurement provided by monitors

7. In the past
• The primitive method of monitoring in
the past was continuous Visual
monitoring of respiration and overall
clinical appearance
• Finger on pulse for palpation of the
pulsations throughout the operation
• Blood pressure (sometimes)

8. • In recent years, monitors have become
popular due to the advance in technology.
• They provide additional information by
automation and free the anaesthetist’s
hand to perform various other tasks such as
preparing drugs, administration of drugs
and writing notes.

9. Monitoring devices
• Non-invasive blood pressure
• Pulse Oximeter
• Capnography
• Electrocardiogram
• Apparatus to monitor temperature
• Peripheral nerve stimulator
Essential monitors
is applied to every patient
regardless of age, physiological
fitness of the patient, or the
duration and magnitude of
surgery

10. Monitoring devices
• Invasive blood pressure
• Central venous pressure
• Pulmonary artery pressure
• Urine output
Additional monitors
- Major complex surgery
– Patients with significant co-
morbidity

11. Monitoring the Patient
• Monitoring devices supplement clinical observation
• Appropriate clinical observations may include mucosal colour,
pupil size, response to surgical stimuli and movements of the
chest wall and/or the reservoir bag.
• The anaesthetist should undertake palpation of the pulse,
auscultation of breath sounds and, where appropriate,
measurement of urine output and blood loss.

12. Monitors for oxygenation
• Oxygenation is how well the lungs are delivering oxygen via the
blood to tissue. this is measured with pulse oximeter.
• It measure oxygen saturation by spectrophotometry in intact
tissue
• Normal SpO2 :95-100%

13. Pulse Oximeter
• Two LEDs producing beams at red & infrared
frequencies in alternating sequence which is
picked up by a photo-detector across a
vascular bed.
• A microprocessor analyses the absorption at
both red & infrared frequencies and converts
the result into the percentage oxygen
saturation

14. Pulse Oximeter
• probe is attach to Finger or ear lobe
• They are accureate to +-2%
• Alarms are provided for level of saturation if outside the preset
value.
Disadvantages
- Affected by extraneous light
– unreliable with carboxy and
metHb
- Unreliable when there is
excessive movement of patient
- Shock, hypotension and
hypothermia affect reading
Advantages
- Non invasive
- Simple to use
- No warm up time
- Not affected by skin pigment

15. Monitors for ventilation
• Ventilation is the exchange and circulation of gases in the lungs
• During spontaneous ventilation, observation of the reservoir bag
may reveal a leak, disconnection, high pressure or abnormalities
of ventilation.
• Carbon dioxide concentration monitoring will detect most of these
problems.
• Capnography is thus use to measure expired CO2

16. Capnography
• Capnography is therefore an essential part of routine monitoring
during anesthesia
• Continuously monitor end tidal CO2 which correlate well with
PaCO2 in absence of pulmonary disease.
• ETCO2 is a function of co2 production, alveolar ventilation and
pulmonary circulation
• ETCO2= 35mmHg
• PaCO2= 40mmHg

17. Capnography
• It works on the principle that Co2 is absorbs infrared light in
proportion to its concentration

19. Cardiogenic oscillation-
Seen as relaxant wears off
Seen with high CO2
Seen in obstruction that limit
expiration
Unequal emptying of lungs

20. ETCO2 Importance
• Adequate ventilation
• Correct placement of endotrachea tube
• Indicator of the degree of rebreathing
• Indicator of cardiac output
• Malignant hyperthermia
Inaccurate ETCO2 Estimation
- Rapid respiration
- Chronic pulmonary disease
- Severe hypotension

21. Monitors for circulations
• The circulation is monitor using heart rate, rythm and blood
pressure
• Normal heart rate is 60-100
• The heart rate is continually measured using
• Pulse oximeter
• ECG
• Intra-arterial line and transduccer

22. Heart rate
• tachycardia (> 100) should raise the suspicion of
• Light anaesthesia, inadequate analgesia
• Relative hypovolaemia
• Drug induced – beta agonists, vasopressors,
• bradycardia (< 60) can be due to
• beta-blockade, intense vagal stimulation
• high dose opiates
• conduction defects

23. Blood pressure
• Representative of the cardiac output and is dependant on
• Cardiac contractility & stoke volume(SV)
• Peripheral vascular tone (SVR)
• Venous filling and circulating blood volume
• It can be measured -
• Non-invasively (oscillometric)………indirect method
• Invasively ( intra-arterial canula)…….direct method

24. Blood pressure-non invasive
• Non-invasive methods includes,
• .
• Palpation method.
• Auscultation method.
• Oscillometry.
• Doppler (U/S) probe.
• Arterial tonometry

25. Non-invasive- Oscillometry
• Current automatic noninvasive blood pressure monitors work on
the oscillometric technique.
• a pressure transducer measures the pressure and oscillations.
• A microprocessor controls the inflation, deflation and display of
numerical value
•

26. Non invasive-osscilometry
• The cuff inflates well above the systolic pressure and then
deflates slowly.
• The monitor first senses oscillations as the cuff drops to systolic
pressure.
• The point at which the oscillations are the strongest is read as the
mean pressure.
• Most of these devices calculate the diastolic pressure after they
measure the systolic and mean pressures

27. NBP-oscillometry disadvantages
• Inaccurate in the presence of arrhythmias.
• Not reliable in extremes of BP (underestimates when too high and
vice versa).
• motion (especially shivering) on the part of the patient or the
surgeon leaning against the cuff will cause false readings or failure
to get a reading

28. Blood pressure-Invasive
• Direct measurement of BP using an intra-arterial canula connected
to a pressure transducer
• In the transducer mechanical energy of movement of diaphragm
due to arterial pulsations is converted in to an electrical energy
and displayed as blood pressure reading on the monitor.
• The cannula is continuously flushed with heparinised normal saline
to prevent clotting

29. Blood pressure- invasive
• Cases where rapid blood pressure
changes is anticipated as in
cardiovascular disease, major blood
loss, cardiac surgery, intracranial
surgery and induced hypotension
• Need for frequent arterial blood gas
analysis
• Cases where non-invasive blood
pressure may be inaccurate:
arrhythmias, morbidly obese patien
Complications of invasive
Hematoma
Arterial thrombosis
Embolism
Necrosis of the extremity involved
Indication

30. ECG
• ECG is a surface recording of the electrical activity of the
myocardium. It is recorded by connecting various electrodes
through which electrical potentials are measured.
• ECG provides information on heart rate, rhythm,some indication
of myocardial ischaemia and disturbance of certain electrolyte

31. ECG
• It doesn’t provide any indication about the adequacy of
circulation.
• ECG is essential for appropriate diagnosis of peri-operative
arrhythmias and ischaemic changes

32. Temprature Monitoring
• detect/prevent hypothermia
• monitor deliberate hypothermia
• adjunct to diagnosing MH
• monitoring CPB cooling/rewarming

33. Temperature monitoring
• Px temperature is usually measured continually
• Body temperature usually decreases during intra-operative period.
General anaesthesia depresses
thermoregulatory centre
most of the anaesthetic agents
produce vasodilatation, facilitating
heat loss.
infusion of cold i.v. fluids,
exposure of
body cavity, low room temperature
all

34. Temperature monitoring
• Thermistor
• Works based on resistance which is temperature dependent
• Placed in oesophagus nasopharynx or rectum
• Infrared-typmpanic membrane thermometer

35. Monitoring neuromuscular block
• This helps to assess
• the onset of neuromuscular block,
• depth of neuromuscular block
• and adequacy of recovery from neuromuscular block.
• Most often a peripheral nerve stimulator is used.

36. • The principle involves transcutaneous electrical stimulation near a
• nerve and assessment of muscle response by visual inspection or
by palpation of the
• muscle.

37. Additional -Central Venous Pressure
• It reflects the filling pressure of the RV & can be measured using a
central venous catheter
• The catheter can be introduced from either the internal jugular
vein or the subclavian vein
• A pressure tranducer converts it to a venous wave form with
values displayed on the monitor
• It indicates the venous filling or ‘preload’ of the heart

38. Additional-CVP
• Useful for close monitoring via a CVP catheter
• Fluid management in major surgery involving sudden, significant
blood loss & fluid redistribution
• Directing fluid therapy in hypovolaemia & shock
• Pre-existent cardiac disease – cardiac output dependent on critical
filling pressures
• For infusion of inotropic drugs, caustic and irritant drugs and
hyperosmolar fluid

39. Complication of CVP
• Complications :
• Carotid puncture 􀃆haematoma
• Arrhythmias
• Air embolus
• Pneumothorax

40. Pulmonary artery pressure
• They are inserted into the IJV or the subclavian vein and floated
into the P.A
• • Long catheter with a balloon tip which is lodged in a pulmonary
capillary with the blood flow
• • It is connected to a computer which can calculate cardiac
output & cardiac index by the thermodilution technique
• • Use declined since the availability of safer, non invasive
techniques such as oesophageal doppler which provides similar
information on cardiac indices

41. Other uses of CVP
• Measures/calculates the following :
• CVP, RA pressure
• PA pressure,PCWP
• SV/ SV Index
• SVR / SVR Index
• Mixed venous oxygen saturation
• Degree of shunting in the pulmonary circulation

42. Cardiac output
• Oesophageal Doppler
• Minimally invasive monitoring of cardiac output and other cardiac
indices
• Has replaced pulmonary artery catheter for above
• Guides fluid replacement and drug therapy
• Indicated forPatients over 65
• Fluid loss >500ml
• ASA III
• major procedures exceeding 2 hours

43. conclusion

44. Thank you