Monitoring in Anesthesia Done by : Heba Abu Khalaf

Objectives 1. Guidelines to the practice of anesthesia and patient monitoring 2. Anesthesia depth 3. Elements to monitor ( Oxygenation, Ventilation, Circulation, Temperature) 2.1. ECG 2.2. Pulse Oximetry 2.3. Blood Pressure 2.4. central venous line and pressure  2.5. Capnography and EtCO2 2.6. How to identify Cyanosis 2.7. The oxyhemoglobin dissociation curve 3. Normal values for a healthy adult undergoing  anesthesia

Guidelines to the practice of anesthesia and patient monitoring: 1. an anesthetist present: “the only indispensable monitor” The doctor should present in the room & monitor the conduct of all general or regional anesthetics 2. A completed pre-anesthetic checklist.     (ASA class, Hx &physical exam, investigations, NPO policy )

Con’t... 3.  perioperative anesthetic record: HR and BP every 5 min, O2 saturation, End Tidal CO2, dose and route of drugs and fluids 4. continuous monitoring: patient’s oxygenation, ventilation, circulation and temperature .

I. Anesthetic Depth: Elements to Monitor : Patients with local or regional anesthesia provide verbal feedback regarding well being. •Onset of general anesthesia signaled by lack of response to verbal commands, in addition to loss of blink reflex to light touch. Inadequate anesthesia can be signaled by : Facial grimacing or movement of arm or leg. //blink reflex present when eyelashes lightly touched, But with muscle relaxants ( fully paralysis), it can be signaled by : Hypertension, tachycardia, tearing or sweating. { Due to pain }

Con’t... Excessive anesthesia can be signaled by : Cardiac depression, bradycardia, and Hypotension. also may result in hypoventilation, hypercapnia and hypoxemia when muscle relaxants is not given.  

2. Oxygenation >> inspired Oxygen we monitor it Clinically through observation of patient / skin color also by : 1) pulse oximetry ( SaO2 ) 2) Blood gas analysis ( Pao2 ) 3) fraction of inspired O2 (FiO2) Quantitavely monitored by using oxygen analyzer, equipped with an audible low oxygen concentration alarm.

• Pulse Oximetry: ** mandatory monitor for any anesthetic ,, including cases of moderate sedation **measure { non invasively} pt’s SpO2 ( arterial oxy saturation) And blood flow fluctuation by plethysmograph (waveform of pulse oximeter “arterial waveform “ >> indicates that pulse oximeter is reading the arterial oxy saturation

Technique >> sensor containing light sources (Red and Infra-red light) & light detector is placed across finger tip , toe , earlobe or any other perfused tissue that can be transillumintaed processing >>analyze amount of light absorbed by the 2 wavelengths,, then determining concentrations of oxygenated and deoxygenated forms through only arterial blood light absorption is differ between oxyHb and deoxyHb. analysis of oxygenation in each beat

Inaccurate measurements ,, causes of oximetry artifact : Also it provides an indication of tissue perfusion & measure heart rate Inaccurate measurements ,, causes of oximetry artifact : 1) poor tissue perfusion (shock & hypotension) 2) movement 3)dysrhythmias 4) hypothermia ( cold extremities ) 5) cardiac arrest •Pulse oximetry (SpO2) measures oxy-, deoxy-, met-, and carboxyHb.

It used for monitoring oxygen delivery to vital organs Pulse oximetry is never used for rapid diagnosis of hypoxia ( that may occur in unrecognized esophageal intubation ) It used for monitoring oxygen delivery to vital organs Also in recovery room , it helps identify post op pulmonary problems such as hypoventilation / bronchospasm / atelactasis So timing of Spo2 monitoring >> before intubation , through the surgery ,, after extubation & recovery

Pulse oximeter tone changes with desaturation from high to low(deep) sound So just by listening to the monitor ,,you can recognize the 1) HR. 2) O2 saturation Healthy patient under GA (O2= 100%) >> Spo2 96-100%

Rules : # pay attention to the sound of pulse oximetry # Always remember that your clinical judgment is much more superior to the monitor ,, check pt’s color for cyanosis ,, lips ,, nails

4.Temperature ** should be monitored for patients under anesthesia ** post op temp. >> used as quality anesthesia indicator ** hypothermia associated with : 1) delay drug metabolism, 2) impaired coagulation ** hyperthermia has bad effects peri operatively leading to : 1) tachycardia 2) vasodilation 3) neurological injury So temp. Must be measured & recorded peri operatively

Hypothermia (<36°C) Normal heat loss during anesthesia averages 0.5 - 1 C per hour, but usually not more that 2-3 C Temperature below 34C may lead to significant morbidity Hypothermia develops when thermoregulation fails to control balance of metabolic heat production and environment heat loss Normal response to heat loss is impaired during anesthesia • Those at high risk are elderly, burn patients , spinal cord injuries

Causes of Hypothermia (<36°C) **intraoperative temperature losses are common (e.g. 90% of intraoperative heat loss is transcutaneous) >> due to: 1) OR environment (cold room, IV fluids, instruments) 2) open wound ## prevented with forced air warming blanket and warmed IV fluids

Impact of Hypothermia 1) Increased risk of wound infections >> due to impaired immune function 2) Increases the period of hospitalization by delaying healing 3) Reduces platelet function and impairs activation of coagulation cascade increasing blood loss and transfusion requirements 4) Decreases the metabolism of anesthetic agents prolonging post- operative recovery

Causes of Hyperthermia (>37.5-38.3ºC) 1) malignant hyperthermia 2) drugs (e.g. atropine) 3) blood transfusion reaction 4) infection/sepsis 5) •  Increases in metabolic rate secondary to: –Thyrotoxicosis –Pheochromocytoma 6) Excessive environmental warming

Continuous temperature measurements monitoring (Thermometry) is mandatory if changes in temperature are suspected. ** intra op ,, temp measured by thermistor or thermocouple Monitoring sites : >> esophagus >> tympanic membrane >> nasopharynx. >> Peripheral sites axilla & rectal.

2. Ventilation Clinically, monitored through a correctly positioned endotracheal tube, also observing chest expansion and breath sounds over both lungs. •Quantitavely by ETCO2 analysis, equipped with an audible disconnection alarm. •Arterial blood gas analysis for assessing both oxygen and ventilation.

3. Circulation Clinically monitored by pulse palpation, heart auscultation & monitoring intra-arterial pressure (MAP normally between 70 - 100 mmHg) or oximetry. Quantitively using ECG & blood pressure measurements every 5 min.

Typical anesthesia monitor

Always remember that your clinical judgment is much more superior to Any monitor monitor is present to help you not to be ignored and not to cancel you brain.

Thank You