Quiz 4 study guide Flashcards
What is the insufficient elimination of carbon dioxide from the body relative to CO2 production
Hypoventilation
What is another definition for hypoventilation?
A reduction in alveolar minute ventilation
What can occur if the body is not able to get rid of CO2?
Respiratory acidosis
How is hypoventilation assessed?
Monitoring the PaCO2 with direct or indirect methods
What is the direct method for monitoring PaCO2?
Arterial or venous blood gas
What is the indirect method of monitoring PaCO2?
Capnograph
ETCO2
What is a PaCO2 reater than 45mmHg known as?
Hypercapnia
What is a PaCO2 reater than 45mmHg known as?
Hypercapnia
What are the causes of hypoventilation?
Any factor that causes a decrease in respiratory rate or tidal volume or an increase in mechanical dead space
How do you control the factors that cause hypoventilation?
Make sure the ET tube is the proper length
Limit the amount of components in the ET tube & respiratory line
What causes a dose dependent hypoventilation
Anesthetic agents
Administering large boluses of induction agents (apnea)
What happens as depth increases?
Excessive CNS depression
Decrease respiratory rate
Decrease in the normal response to an increased CO2
What are the factors that contribute to a decrease in tidal volume?
Abdominal distention
Obesity
Thoracic pain
How dose thoracic pain due to flail chest or fractured ribs lead to a decrease tidal volume?
Unable to generate a big enough breath to exhale the normal tidal volume to keep CO2 levels WNL
What are the factors that contribute to an increase in mechanical dead space?
Malfunctioning or missing one-way valves Improper packing of the CO2 absorbent Cracked inner tube of a coaxial circuit Too many adapters between the ET tube & breathing hoses Not using a septum in the Y-piece ET tube past the incisors
What factors can contribute to the re-breathing of CO2?
Exhausted CO2 absorbent
Malfunctioning scavenging system
Inadequate oxygen flow rates for non-rebreathing circuits
How do you prevent or treat hypoventilation?
Monitor CO2 (indirect or direct)
Asses the depth to make sure not excessive
Use a balanced anesthetic
Investigate the anesthesia machine
What should you do if the PaCO2 is approaching greater than or equal to 45mmHG?
Simply give the patient a breath 1-2 times a minute
What do you do if the PaCO2 is approaching 60mmHg
Intermittent positive pressure ventilation should be started at a controlled rate and tidal volume
How do you keep mechanical dead space to a minimum?
Using appropriate length ET tube
Not using more than one adapter between the ET tube and breathing circuit
Make sure the surgeon is not leaning on the patient
What is reduced oxygen in the blood
Hypoxemia
What does hypoxemia mean?
There is an insufficient amount of oxygen in the arterial blood
How do you monitor for Hypoxemia
By monitoring oxygenation
How do assess oxygenation?
Directly or indirectly
What is the direct method for monitoring oxygenation?
Arterial blood gas
What is the indirect method of monitoring oxygenation?
Pulse Oximeter (SPO2)
What is the predicted PaO2 when compared to inspired oxygen?
4-5 times the inspired oxygen concentration
If a patient is on 100% oxygen what would the PaOC be?
Between 400-500mmHg
What does a PaO2 less than 80mmHg indicate?
Moderate hypoxemia
What does a PaO2 less than 60mmHg indicate?
Severe hypoxemia
When is a patient considered to be hypoxemic?
When the PaO2 falls below 80mmHg
What are the causes of hypoxemia?
Ventilation to Perfusion Inequality
V/Q mismatch
What is V/Q mismatch
Ventilation and blood flow are mismatched at the level of the alveoli
When V/Q mismatch is happening what is occurring anatomically?
Portion of the lung field is ventilated well but does not get the blood flow or perfusion it needs
Vice/versa
What does V/Q mismatch result in?
The inefficient gas exchange between the lungs and pulmonary blood
What is the most common cause of reduced oxygenation in an anesthetized patient?
V/Q mistmatch
When does maximum gas exchange occur?
When the ratio between ventilation (V) and perfusion (Q) are equal to 1
A V/Q ration of <1 means that perfusion is occurring but ventilation is not, what does this contribute to?
Venous admixture
What is venous admixture?
The blood does not become fully oxygenated as it passes through the lungs
Arterial blood is diluted with de-oxygenated blood
What might cause a V/Q ration less than 1?
Atelectasis
Bronchial intubation
What does it mean when a V/Q ratio is greater than 1?
Ventilation is present but perfusion is not
What causes a V/Q ratio of greater than 1?
Dead space ventilation Pulmonary thromboembolism Severe hypovolemia or hypotension Patient in dorsal recumbency Patine in the head-down position for a long time
What is Dead space ventilation termed?
Wasted ventilation
What are other causes of hypoxemia
Diffusion impairment
Anatomical Shunts
Severe Hypoventilation
Low inspired oxygen
What is diffusion impairment?
Any condition that prevents the normal uptake of oxygen from the alveoli to the pulmonary capillary blood
Define Anatomical shunts
Congenital heart abnormalities that cause blood to be shunted from the right side of the heart to the left side without passing through the lungs to become oxygenated
What is more of a concern during the post operative period when the patient is breathing room air
Severe hypo-ventilation
How do you prevent hypoxemia?
Pre-oxygenate patients Intubate patients Minimize anesthesia & surgical time Check oxygen source Calculate the appropriate oxygen flow rate for the type of anesthesia breathing circuit
What is extremely difficult to treat if it happens after the patient is already on 100% O2 during anesthesia?
Hypoxemia
What are the treatment options for hypoexmia?
Increase peak airway pressure to 40 cm H2O
Hold positive pressure for 3-5 seconds
Provide positive end expiratory pressure (PEEP)
How does providing positive end expiratory pressure (PEEP) help with hypoxemia
Causes positive pressure to remain in the lungs at the end of expiration which increases alveolar volumes and recruits collapsed alveoli
What is defined as below normal arterial blood pressure?
Hypotension
How do you indirectly monitor hypotension?
Oscillometric or doppler
How do you directly monitor hypotension?
Arterial catheterization
What defines hyptension in small animals?
less than 80 mmHg
What causes hypotension?
Anesthetic drugs Inhalants Hypovolemia Dehydration Inadequate volume admin Reduced vascular tone Excessive inspiratory pressure on the caudal vena cava Hypothermia Excessive anesthetic depth
How do you prevent Hypotension?
Use a balanced anesthesia approach
Keep the inhalant concentration to a minimum
Provide IV fluids
How do you treat Hypotension?
Turn down vaporizer
Give a 5-20ml/kg bolus of fluids
Consider colloids or hypertonic saline
Consider inotropes (Dopamine, dobutamine)
What is defines as the reduction in the effective intravascular blood volume?
Hypovolemia
What is absolute hypovolemia?
The actual loss of intravascular volume
When do you see absolute hypovolemia?
Intravascular fluid losses exceed intravascular fluid gains
What is relative hypovolemia?
An increase in intravascular space due to vasodilation
How do you monitor for hypovolemia
Physical parameters & monitoring tools are used to help assess adequate circulating blood volume and tissue perfusion
What are the physical parameters that may indicate hypovolemia?
Pale mucous membranes Prolonged CRT Thready pulse quality Cold extremities Tachycardia Hypotension
What monitoring tools are available to help assess hypovolemia?
PCV/TP
Lactate
Urine output
Central venous pressure
A lactate value of more than 2mmol/L can indicate what?
Poor tissue perfusion
An urine output of less than 0.5mL/kg/hr could indicate what?
Poor perfusion/ hypovolemia
What does a low (<0cmH2O) or decreasing CVP suggest?
Hypovolemia
What are the common causes of absolute hypovolemia?
Acute hemorrhage
Water & electrolyte loss
Plasma losses
What does third space loss involve?
Re-distribution of fluid within the body
Intravascular space to interstitial space
What are the causes of relative hypovolemia?
Adverse drug reactions
Sepsis
Anaphylaxis
Anesthesia drugs (Ace & inhalants)
How do you prevent hypovolemia? what are the 5 Ps?
Previous planning prevents poor performance
How do you treat hypovolemia?
Replacement of crystalloid fluids
Colloid therapy
Hypertonic Saline
Blood products
What is the percentage of total blood volume loss a healthy anesthetized animal can tolerate?
10-20%
What are the shock doses of fluids for dogs in severe cases of hypovolemia?
80-90ml/kg
What are the shock doses of fluids in cats with severe hypovolemia?
40-60ml/kg
How do colloids like hetastarch, pentastarch and Voluven help treat hypovolemia?
Restore intravascular volume
Help maintain oncotic pressure
Keep fluid in the intravascular space longer than crystalloid fluids
What is the bolus rate of colloids in dogs and cats?
Dogs = 5-10 mL/kg
Cats + 2-5 mL / kg
What is used for rapid low volume resuscitation in the treatment of hypovolemic shock and causes rapid intravascular volume expansion
Hypertonic saline
How long does hypertonic saline last and what is the rate in cats and dogs?
30 minutes
Dogs = 4-6mL/kg
Cats = 2-3mL/kg
In what patients is hypertonic saline contraindicated?
Severely dehydrated
Cardiac disease
hypernatremic
When is whole blood indicated to treat hypovolemic shock
When greater than 25% of circulating blood volume is lost
When both oxygen-carrying capacity & intravascular volume is needed to be restored
What contains red blood cells, plasma, coagulation factors & platelets?
Fresh whole blood less than 6-8 hours old
What contains red blood cells, plasma, and decreased levels of coagulation factors, and no active platelets?
Fresh whole blood 8-24 hours old
When is Packed RBC indicated?
When the PCV is less than 20% but TP is adequate
Only restores oxygen-carrying capacity
When is plasma indicated to treat hypovolemia?
When the PCV is adequate but the TP is less than 3.5 g/dL
What is defines as a below normal body temperature?
Hypothermia
What is a mild hyothermia?
98-99.9 F
What is a moderate hypothermia?
96-98 degrees F
What is a severe hypothermia?
92-96 degrees F
What is a critical hypothermia?
less than 92 degrees F
How often should temperature be monitored?
every 15-20 minutes
What are the causes of hypothermia?
Heat loss during ansethesia Anesthetic agents Using a non-rebreathing Large surgical incisions Prolonged anesthesia times Cool surgical scrub Placing an animal on a cold operating table
How is heat lost during anesthesia?
Convection
Conduction
Radiation or evaporation
What are ways to prevent hypthermia?
Maintain a warm operating room Utilize warm air blankets Conductive fabric warmers Circulating warm water blankets Fluid warmers Wrap extremities
What are the No-No’s to preventing/treating hypthermia?
microwaved warming devices
Electrical heating pads
What is defined as a below normal blood glucose level?
Hypoglycemia
What should blood glucose levels be maintained between?
70-120mg/dL
What patients should glucose always be monitored in?
Pediatric patients Diabetics Hepatic disease Portal systemic shunts Insulinomas Septicemias Endotoxemias
What are the consequences of hypoglycemia?
Coma Hypotension Long anesthetic recovery Depression Weakness Seizures
How do you prevent/Treat hypglycemia?
Add dextrose to fluids if warranted
What are the common concentrations of dextrose added to fluids?
2.5% and 5%
How do you prepare a dextrose solution?
Add 100mL of 50% dextrose to 900ml of fluid to make a 5% dextrose
What is defined as an above normal body temperature
Hyperthermia
What are the causes of hyperthermia?
Excessive application of heat Fever Contamination of IV fluids High ambient temps Loss of temperature regulation in the CNS Thyrotoxicosis Dissociatives Pure mu opiods (cats)
What is hyperthermia sometimes manifested as?
Malignant hyperthermia syndrome
What is malignant hyperthermia syndrome?
A life-threatening hypermetabolic condition triggered by stress & certain anesthetic agents
What is a Pheochromocytoma?
Neuroendocrine tumor of the medulla of the adrenal glands
Causes sympathetic nervous system hyperactivity
When is treatment of hyperthermia indicated?
when the temperature reaches 105.8 degrees F
What are not recommended as treatments of hyperthermia because it can cause peripheral vasoconstriction
Shivering that leads to further increase core body temperature
Ice packs and full submersion in cool water
What is defined as excessive elimination of CO2 from the body relative to CO2 production or an increase in alveolar minute volume?
Hyperventilation
What does hyperventilation lead to?
Hypcapnia
When is hyperventilation indicated?
When the PaCO2 is less than 35mmHg
What can hyperventilation cause?
Severe cerebral vasoconstriction which may result in brain ischemia
What causes hyperventilation?
Inadequate anesthetic depth or response to pain Overzealous ventilation Hypoxemia Hyperthermia Low inspired O2 concentrations Increased CO2 production
What is the prevention/treatment of hyperventilation?
Assess anesthetic depth Monitor for pain Decrease tidal volume Decrease RR Avoid hyperthermia Use appropriate O2 flow
What is defined as an above normal arterial blood pressure?
Hypertension
What is hypertension is defined as?
MAP > 120mmHg
SAP > 160mmHg
DAP > 95mmHg
What happens if hypertension is left untreated?
Increased myocardial workload & oxygen demand
What is considered hypertension under GA?
greater than 100mmHg
What can hypertension cause damage to?
Eyes Kidneys Heart Brain Peripheral vessels
What are the causes of hypertension?
Pain
Inadequate depth
Hypercapnia
Anesthetic drugs
What underlying disease can cause hypertension?
Renal disease Hyperadrenocorticism Hyperthyroidism DM HF Pheochromocytoma
