Anesthesia 2 - Lecture 1: Monitoring Review & Normals (PDF)

Anesthesia 2 -- Lecture 1 **Indicators of Circulation -- CRT** - Indicates peripheral tissue blood perfusion, (can be misleading) - Slow may result from epinephrine release, low blood sugar, hypothermia, cardiac failure, excessive anesthetic depth, blood loss, pain, shock - Results...

Anesthesia 2 -- Lecture 1 **Indicators of Circulation -- CRT** - Indicates peripheral tissue blood perfusion, (can be misleading) - Slow may result from epinephrine release, low blood sugar, hypothermia, cardiac failure, excessive anesthetic depth, blood loss, pain, shock - Results in reduced temperature of affected part(s) - CRT longer than 2 seconds: prolonged, decreased perfusion possibly due to hypovolemia (dehydration) or peripheral vasoconstriction (e.g during shock) - CRT less than 1 second: normally accompanied by bright red MM, septicemia, hyperthermia (vasodilation) **Sp02 % Saturation** Should be interpreted based on inspired 02 fraction (Fi02) Normal Sp02 values between 95-100% Breathing room air Fi02 = 0.21. Sp02 greater than 95% (hypoxic when less than 95%) Breathing 100% 02 (Fi02 = 1) Sp02 = 100% (hypoxic when less than 98%) **Capnograph** ETC02 = 35-45mmHg INC02 = 0-2mmHg Hypocapnia = less than 35mmHg Hyperventilation = less than 35mmHg Hypercapnia = greater than 45mmHg Hypoventilation = greater than 45mmHg Low ETC02? Assess patient, depth, 02, recall rapid decline or less than 15 = imminent cardiopulmonary arrest High ETC02? IPPV, assess patient Under anesthesia we often tolerate hypercapnia (45-55mmHg) because it has some benefits -- known as permissive hypercapnia (protective, increases vascular tone, helps with hypothermia) High INC02? Low 02 flow? Respiratory depression (low vol/low rate), tachypnea, exhausted soda lime... [Rebreathing C02 / Inspired C02] - Exhausted / malfunctioning C02 absorber   - Inadequate inspiratory flow - Insufficient expiratory time - Faulty (sticky) expiratory valve [Obstructed ETT, Airway, or Circuit or Bronchospasm ] - Exhausted / malfunctioning C02 absorber   - Inadequate inspiratory flow - Insufficient expiratory time - Faulty (sticky) expiratory valve [Esophageal Intubation if Cardiac Output is Good ] - Esophageal intubation (confirmed patient breathed or IPPV given once attached to ADS, if you see no trace the esophagus is likely intubated) - No C02 sensed or very minimal amounts, capnograph is the best monitor to confirm intubation is in the trachea **Esophageal Stethoscope** - Operator end same as regular stethoscope (can not be submerged in H20 or cleaner) - Attaches to a catheter placed down esophagus - Inserted to point of maximal sound intensity - Around 4^th^-5^th^ rib - Must be measured to ensure you do not accidently enter the stomach If it enters the stomach the sphincter will open allowing content to travel up the esophagus and potentially down the trachea - Technique: Measure, lubricate, follow dorsal midline of maxilla, and insert to correct marked distance - A great tool during anesthesia as it provides heart and lung sounds - A confident way to obtain HR in any environment, esp loud environments or a patient who has a lot of draping or surgery occurring on the thorax - Also great for when monitoring devices fail or we need to confirm accuracy **Heart Rate Normals** Cats 120-220bom (bradycardia = less than 100bom, Tachycardia = greater than 260bom) Small Dogs 120-220bpm (Bradycardia = less than 60bpm. Tachycardia = greater than 190bpm)\ Large Dogs 60-120bpm (Bradycardia = less than 50bpm Tachycardia = greater than 150bom) Peripheral Arterial Pulse & Strength **Common Tech Errors in BP Measurements** - Cuff overly wide = false low reading - Cuff overly small or narrow = falsely high reading - Cuff not placed snug = false high reading - Cuff placed over joint = less likely to compress artery - Hole in cuff = pressure leaks out too fast to reliably record - Cardiac arrythmias = erratic reading - Taping an Oscillo metric cuff (should never do that) Ok to tape closed a doppler cuff tho [Blood Pressure Normals ] Mean arterial pressure = average pressure through cardiac cycle Main & best indicator of tissue perfusion MAP = Diastolic BP + 1/3 (systolic BP -- Diastolic BP) Dog & Cat Normal Mean = 60-90mmHg Dog & Cat Normal Systolic = 110-160gmHG Dog & cat Normal Diastolic = 50-70mmHg Hypotension: Must keep BP above these values (minimally acceptable values) Mean 60mmHg Systolic 80mmHg **ECG** Common Causes of Anesthetic -- Related Arrhythmias - Inadequate anesthesia / analgesia - Bradycardia - Tachycardia - Hypoxemia - Hypercapnia - Hypotension - Hypo/hyperthermia - Electrolyte abnormalities (potassium and magnesium) - Oculo-cardiac reflex