Monitoring in anaesthesia

1. MONITORING IN
ANAESTHESIA

2. INTRODUCTION
 Monitoring is important to prevent anaethesia
complication
 Sophisticated monitor available,
⚫ only to aid
⚫ not to fully dependent on them
 Anaesthetist vigilance is the best

3. MONITORING
BASIC ADVANCE

4. BASIC
MONITORING

5. BASIC MONITORING-
CLINICAL MONITORING
1. Pulse rate
2. Color of skin
3. Blood pressure
4. Inflation of chest
5. Precordial and esophageal stethoscopy
6. Signs of sympathetic over activity
7. Urine output (>0.5ml/min)

6. ADVANCE
MONITORING-
INSTRUMENTAL
MONITORING

7. INSTRUMENTAL
MONITORING
CVS
RS
℃/℉
MSK
CNS
BLOOD
LOSS
EXPIRED
GAS

8. 1. CARDIOVASCULAR
MONITORING

9. Cardiovascular
monitoring
Non - invasive Invasive Semi - invasive

10. 1. Non invasive
ECG
Non invasive blood
pressure - NIBP

11. 1.ECG
Mandatory monitor to detect :
 Arrhythmia – lead II
 Ischemia – lead V5
 cardiac arrest.

12. 2. NIBP
 Measure blood pressure at set intervals
automatically by automated oscillometery.
 Cuff size should cover 2/3 of arm
⚫Small cuff for children
⚫Too large (underestimate)
⚫Too small (over estimate)

14. TRANSESOPHAGEAL ECHOCARDIOGRAPHY (TEE)
 Most sensitive to detect
any wall motion
abnormality
⚫ ischemia ,
⚫ valvular dysfunction,
⚫ air embolism

15. 3. Invasive Monitoring
nvasive blood pressure
- IBP
Central Venous
Pressure Monitoring -
CVP
Pulmonary artery
catherization

16. 1. IBP
 Required in patient mandates for beat to beat
monitoring
 Gold standard
 Accuracy
⚫ measure the difference in IBP & NIBP not more than 5-
8mmHg
 Radial Artery
 Brachial Artery
 Femoral Artery
 Dorsalis Pedis Artery

17.  Allen’s Test
⚫ Normal - <7s
⚫ Borderline – 7-14s
⚫ >15s – contraindicated

18. > CANNULATION COMPLICATION
 Arterial injury, spasm, distal ischemia
 Thrombosis, embolization
 Sepsis
 Tissue necrosis
 Fistula and aneurysm formation
 *prevention : continuous flush with/out heparin

19. 2.CENTRAL VENOUS PRESSURE
MONITORING (CVP)

20. > INDICATION
 Major surgeries where large fluctuations in haemodynamics
are expected.
 Open heart surgeries.
 Fluid management in shock.
 As a venous access.
 Parenteral nutrition.
 Aspiration of air embolus.
 Cardiac pacing.
⚫ Normal CVP is 3 to 10 cm of H20 (or 2-8 mmHg).
⚫ In children CVP is 3 to 6 cm of H20.
 CVP more than 20 cm of H2O indicates right heart failure.

21. >TECHNIQUE OF CVP CATHETERIZATION (THROUGH
INTERNAL JUGULAR VEIN)
Seldinger technique
1. Patient lies in Trendelenburg position – to decrease
chance air embolism
2. The cannula with stylet is inserted at the tip of
triangle formed by two heads of sternomastoid and
clavicle. The direction of needle should be slightly
lateral and towards the ipsilateral nipple.
3. Once the internal jugular vein is punctured. Stylet is
removed and a J wire is passed through cannula
4. Now the CVP catheter is railroad over the J wire
5. The tip of catheter should be at the junction of superior
vena cava with right atrium – 15 cm from entry point

23. > CVP IS INCREASED IN :
 Fluid overloading
 Congestive cardiac failure.
 Pulmonary embolism
 Cardiac tamponade
 Intermittent positive pressure ventilation with PEEP
 Constrictive pericarditis
 Pleural effusion
 Hemothorax
 Coughing and straining

24. > CVP IS DECREASED IN :
 Hypovolemia and shock
 Venodilator
 Spinal / epidural anaesthesia
 General anesthesia – by causing vasodilatation
Low CVP + low BP = Hypovolemia
High CVP + low BP = pump failure

25.  X ray chest is performed to check the position of
catheter and to exclude pneumothorax
Complication
 Air embolism
 Thromboembolism
 Cardiac arrhymias
 Pneumothorax/haemothorax/chylothorax
 Cardiac perforation/cardiac tamponade
 Sepsis – late complication
 Trauma to brachial plexus, carotid A,phrenic N,airway

26. 3. PULMONARY ARTERY CATHETERIZATION
 It is reserved only for very major cases in severely
compromised patients because cost, technical
feasibility, complications
 Swan Ganz catheter - It is balloon tipped and flow
directed by pressure recording,pressure tracing and
catheter tip
 Indicated by sudden rise in diastolic pressure

30. > INDICATION :
 Measuring cardiac chambers pressure (except left
ventricle).
 Calculating cardiac output
 Measuring pulmonary artery occlusion pressure
(PAOP)
 Taking sample for mixed venous blood
 Titration of fluid infusion

31. > COMPLICATION
 Minor arrhymias – most common
 Pulmonary artery rupture
 Severe arrhymias
 Death

32. 2.RESPIRATORY
MONITORING

33. RESPIRATORY MONITORING
1. Pulse oximetry
2. Capnography
3. Blood gas analysis
4. Lung volumes
5. Oxygen analysers
6. Airway pressure monitoring
7. Apnea monitoring

34. 1. PULSE OXIMETRY
 Oxygen saturation – SpO2
 Normal SpO2 - 97 – 98 %
 Probe is applied at :
⚫ finger
⚫ nail bed,
⚫ toe nail bed ,
⚫ ear lobule,
⚫ tip of nose
 Uses : detection of hypoxia intra/post operative

37. > ERRORS
 Carboxyhaemoglobinemia
 Methhemoglobinemia
 Anemia
 Hypovolemia and vasoconstriction
 Nail polish
 Shivering
 spO2 below 60%
 Skin pigmentation
 Dyes

39. 2. CAPNOGRAPHY
 It is the continuous measurement of end tidal
(expired) carbon dioxide (ETCO2) and its
waveform.
 Normal: 32 to 42 mmHg (3 to 4 mmHg less than
arterial pCO2 which is 35 to 45 mmHg).
 Principle : infrared light absorbed by carbon
dioxide
 Important and sensitive monitoring

41. 3. BLOOD GAS ANALYSIS
Precaution
 Glass syringe is preferred for sampling
 Syringes should be heparinized
 Samples should be stored in ice
 Sample from radial or femoral
 Important in
⚫ Thoracic surgery
⚫ Hypothermia
⚫ Hypotensive anaesthesia

42. NORMAL VALUES ON ROOM AIR
pH - 7.38 to 7.42
Partial pressure of oxygen
(p02)
- 96 to 98 mmHg
Partial pressure of carbon
dioxide (pCO2)
- 35 to 45 mmHg
Bicarbonate (HCO3) - 24 to 28 mEq/L
Oxygen saturation (SpO2) - 95 to 98%
Base deficit -3 to + 3

43. CONT
 Mixed venous oxygen in the best indicator of
cardiac output i.e., tissue oxygenation
 Arterial oxygen is the better indicator of
pulmonary function.
pO2 -40 mmhg
pCO2 -46 mmhg
Oxygen saturation -75%

44. > OTHERS
 LUNG VOLUMES – spirometer
 OXYGEN ANALYSERS
⚫ Monitor actual value oxygen delivered
⚫ Fitted in inspiratory in limb of breathing circuit
⚫ Useful in closed circuit (use low flow oxygen)
 AIRWAY PRESSURE MONITORING
⚫ It should less than 20 – 25cm H2O
⚫ Low pressure – disconnection
⚫ High pressure – obstruction in tube or circuit and
bronchospasm

45. 4. APNEA MONITORING (MONITORING OF
RESPIRATION)
 Apnea is cessation of respiration for more than 10s.
Intubated patients
 Capnography - Most sensitive and cost effective to detect apnea
 Airway pressure monitor
Non intubated patients
 Monitoring the airflow at nostrils (acoustic probe)
 Detection of chest movements
 Impedence plethysmography – chest is encircled by a coil
 Transthoracic impedence pulmonometery
For intubated and non intubated patient
 Pulse oximeter

46. 3. TEMPERATURE
MONITORING

47. > INDICATION
 High incidence of intra-operative hypothermia
 Usually in
⚫ Cardiac surgery
⚫ Infant
⚫ Children
⚫ Adult with burns
⚫ Febrile patient
⚫ Malignant hyperthermia patient

48. > TEMPERATURE MONITORING
Core temperature monitoring sites :
 Esophagus
 Pulmonary artery
 Nasopharynx
 Tympanic membrane – most accurate for brain
temperature

49. 1. HYPOTHERMIA
 Hypothermia may be defined as core temperature less
than 35 ℃.
⚫ Mild : 28 – 35 ℃
⚫ Moderate : 21 – 27 ℃
⚫ Severe : <20 ℃
 Most common thermal perturbation seen in anaesthesia
because :
 Most anaesthetics are vasodilators, causing heat loss and
hypothermia
 Cool room temperature
 Cold intravenous fluids.
 Evaporation

50. > SYSTEMIC EFFECTS OF HYPOTHERMIA
CVS
Bradycardia
Hypotension
Ventricular arrhythmias if temperature is less than 28°C
Respiratory system
Respiratory arrest below 23°C
O2 dissociation curve is shifted to left
Blood
Increased blood viscosity and platelet count

51. Acid base balance
 Increased solubility of blood gases
 Acidosis – increased lactic acid production d/t blood
stasis
Kidney
 Decresed GFR
No urine output at 20°C
Endocrine system
 Decreased adrenaline and nor-adrenaline
 Hyperglycemia

52. > TREATMENT OF LNTRAOPERATIVE
HYPOTHERMIA
 Warm intravenous fluids
 Increase room temperature: The ideal operation
theatre temperature for adults is 21°C and for
the children 28°C
 Cover the patient with blankets
 Forced warm air by a special instrument ( Bair
Hugger airflow device)

54. > USES OF INDUCED HYPOTHERMIA
 Brain protection in cardiac arrest or neurovascular
surgeries. Brain can be protected for 10 minutes at
30°C
 For tissue protection against ischemia in cardiac
surgeries done on heart lung machine

55. 4. NEUROMUSCULAR
MONITORING

56. 1. NEUROMUSCULAR MONITORING
 Adductor pollicis (ulnar nerve)
 Others : Orbicularis oculi, Median nerve, Posterior tibial
nerve , Peroneal nerve
Required for :
 Myasthenia gravis
 Duchenne’s muscular dystrophy
 Train of four (TO4) is the most useful method for clinical
monitoring.
 In this 4 stimuli, each of 2 Hz for 2 sec are given and
recordings are taken.
Normal : amplitude height of fourth and first response will
be the same. T4/T1 = 1

59.  Usage of depolarizing muscle relaxant – all 4 amplitude
will be decrease
 Non depolarizing muscle relaxant – first there will be
decrease in T4/T1 ratio followed by fading which means
T4 response will disappear first then T3 and so on.
 Assess reversal
⚫ Ratio 0.7 indicate adequate reversal
⚫ Recovery guaranteed at ratio 0.9
 Usefull in dx phase II block
(patient on Sch show fading its pathgonominic of phase II
block)

60. >OTHER STIMULI USED FOR
NEUROMUSCULAR MONITORING
 Single twitch
 Tetanic stimulation
 Post tetanic facilitation
 Double burst stimulation (DBS 3,3 )

62. 5. CENTRAL NERVOUS
SYSTEM MONITORING

63. MONITORING DEPTH OFANAESTHESIA
Clinically :
Signs and symptoms of light anaesthesia are:
 Tachycardia.
 Hypertension.
 Lacrimation.
 Perspiration.
 Movement response to painful stimuli.
 Tachypnea, breath holding, coughing, laryngospasm,
bronchospasm.
 Eye movements.
 Preserved reflexes

64.  EEG
 Patient evoked response
 Bispectral index
 Entropy – detection of abnormalities in EEG at
higher concentration of anaesthetic agents

65. EVOKED RESPONSE
Assessing the integrity of neuronal tissues during
surgeries
1. Somatosensory evoked pontential ( SSEP)
⚫ Any surgeries that can compromise vascular supply of
sensory tract
⚫ Spine surgeries, repair of thoracic and abdominal aorta
aneurysm, brachial plexus exploration and surgery of brain
area
2. Auditory evoked potential (AEP)
⚫ For procedures involving auditory pathways
⚫ Resection of acoustic neuroma and posterior fossa surgeries
3. Visual evoked potentials (VEP)
⚫ For procedures involving visual tracts
⚫ Optic glioma, pituitary tumours

66. ELECTROCEPHALOGRAM (EEG)
 Other than measure depth of anesthesia , EEG also
can asses cerebral ischemia during neurovascular
surgeries – carotid endarterectomy
Effect of anesthetic agents and modalities on EEG
 All inhalational and intravenous anesthetic agents
produces biphasic pattern on EEG
 Lower dose – causing excitation( high frequency
and low amplitude waves).
 High dose - causing depression (high amplitude
and low frequency waves)

67. 6. MONITORING BLOOD LOSS
 Estimation of blood loss is done by weighing blood
soaked swabs, sponges (Gravimetric method) and
estimation of blood loss in suction bottle (Volumetric
method).
 Most accurate method is colorimetric method.
On an average (a rough guide):
 Fully soaked swab means 20 ml of loss.
 Fully soaked sponge means 100 to 120 ml of loss.
 A fist of clots means 200 to 300 ml of loss.

69. 7. EXPIRED GAS ANALYSIS
 There is multigas analyzer which measures
concentration of anaesthetic vapors like nitrous
oxide and inhalational agents like halothane,
isoflurane etc.
 These are mass spectrometers and Raman gas
analyzers.