Monitoring in Anesthesia
Dr.Arkan Jaafar , M.D.
Anesthesiologist ,Medical college of Mosul
OXYGENATION
• Oxygenation is monitored clinically by providing
adequate illumination of the patient's color and by
pulse oximetry
• pulse oximeter measure :
1. The oxygen saturation of haemoglobin in arterial
blood - which is a measure of the average amount of
oxygen bound to each haemoglobin molecule. The
percentage saturation is given as a digital readout
together with an audible signal varying in pitch
depending on the oxygen saturation
2. The pulse rate - in beats per minute .
VENTILATION
• Ventilation is monitored clinically by verification
of a correctly positioned endotracheal tube as well
as by observing chest excursions, reservoir bag
displacement, and breath sounds over both lung
fields.
• Ventilation is quantitatively monitored using end
tidal carbon dioxide (ETCO2) analysis as well as
an audible disconnection alarm on all
mechanically ventilated patients
CIRCULATION
• palpation of the pulse
• auscultation of heart sounds
• Blood pressure measurement :
-Automated non-invasive BP measurements NIBP
-lnvasive BP monitoring :The radial artery at the
wrist is the most common site for an arterial
catheter insertion. The femoral, brachial, and
dorsalis pedis arteries are alternative sites
• A central venous pressure (CVP) catheter
provides an estimate of the right atrial and right
ventricular pressures. The CVP reflects the
patients blood volume, venous tone, and right
ventricular performance. CVP 1 - 10 mmHg
• Electrocardiogram (ECG)
The ECG monitors the conduction of electrical
impulses through the heart. It is used to determine
the heart rate and to detect and diagnose
arrhythmias, myocardial ischemia, pacemaker
function, and electrolyte abnormalities
• Temperature :
- Core temperature: measured through tympanic
membrane, nasopharynx, esophagus,rectal ,
urinary bladder , pulmonary artery.
- Peripheral temperature
• Urinary output : should be monitored hourly
Oliguria:- urinary output <0.5 ml/kg/h
• Peripheral nerve stimulator :
Monitoring neuromuscular function of patient
receiving neuromuscular blocking agent
Arterial Blood Gas Interpretation
ABG
• Acid- base disturbances are indicators of serious
underlying pathology
• Arterial blood gas examination is a useful investigation in
patients with suspected respiratory or metabolic disease
• serial blood gas investigation can monitor the progress or
treatment of the underlying disease.
• PH is the negative log of the H+ ion concentration
• PH is important because H+ ions react highly with
cellular proteins resulting in alterations in their function.
Therefore, avoiding acidemia and alkalemia by tightly
regulating [H+] is essential for normal cellular function
Blood samples :
• Radial artery
• Brachial a.
• Axillary a.
• Dorsalis pedis a.
• Femoral a
Blood gas normal values
• PH: 7.35- 7.45; measures blood acidity &
concentration of hydrogen ions
• PaCO2: 35- 45 mm Hg; measures partial pressure of
carbon dioxide
• HCO3: 22- 26 mEq/L; measures amount of bicarbonate
• Base excess (BE) (-2.0 to +2.0 mEq/L) The base
deficit (BD) is the number of mEq/L of base (or acid)
needed to titrate a serum pH back to normal at 37°C
while the PaCO2 is held constant at 40 mmHg, thus
eliminating the respiratory component .Therefore, the
BD represents only the metabolic component of an
acid-base disorder
• PaO2: 80- 100 mm Hg; measures partial pressure of
oxygen (at sea level , FiO2 = 21% , Age-dependent)
• SaO2 93-98%
ABG provides an assessment of the following:
• Oxygenation (PaO2 , O2 saturation). The PaO2 is the
amount of oxygen dissolved in the blood and therefore
provides initial information on the efficiency of
oxygenation.
• Ventilation (PaCO2). The adequacy of ventilation is
inversely proportional to the PaCO2, so that when
ventilation increases, PaCO2 decreases, and when
ventilation decreases, PaCO2 increases.
• Acid-base status (pH, HCO3, and base deficit).
The Terms
ACIDS
• Acidemia
• Acidosis
• ↓ PH
– Respiratory
CO2
– Metabolic
HCO3
BASES
– Alkalemia
– Alkalosis
– ↑ PH
• Respiratory
CO2
• Metabolic
HCO3
ABG
• PH → 7.35 – 7.45
• PaCO2 → 35 – 45 mmHg
• HCO3 → 22 – 26 mEq/L
• BE
→ - 2 ─ +2
• PaO2 → 80 – 100 mmHg (at
sea level , FiO2 = 21%)
• SaO2
→ 93 – 98%