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Principles I Test 2

Ventilators and Respiratory Monitoring

QuestionAnswer
True or False: high tidal volumes do not prevent atelectasis and do not improve gas exchange True
Uncoordinated/asynchronous chest movement due to paralytics and deepened anesthetic state can produce what 2 things? V/Q mismatches and intrapulmonary shunting
Do our lungs naturally operate on positive pressure ventilation or negative pressure ventilation? What about ventilators? Natural = negative pressure ventilation; Ventilators = positive pressure ventilation
What are 4 causes of ventilator-induced lung injury? volutrauma, barotrauma, atelectrauma, biotrauma
What is volutrauma? overdistension of alveoli
What is barotrauma? excessive pulmonary pressures
What is atelectrauma? repeated opening and collapse of atelectatic lung units
What is biotrauma? inflammatory mediator release into alveoli and surrounding bronchiole spaces; this can be caused by volutrauma, barotrauma, atelectrauma
What can happen in pressure controlled ventilation if PiP is increased and compliance is increased? volutrauma
At what peak inspiratory pressure can barotrauma occur? > 35 - 40 cmH2O
What is the most important determinant of barotrauma? the inspiratory plateau pressure
Plateau pressure most accurately reflects what? the end inspiratory volume that leads to lung injury
Biotrauma does not just occur in the lung, it can cause distant organ injury as well. Why? inflammatory release into systemic circulation
True or False: mechanical ventilation at even low tidal volumes and for short periods of time may activate an inflammatory response in the lung (healthy or already injured). True
What is good for artificial positive pressure ventilation can be detrimental to circulation. Why? it increases pulmonary vascular resistance, can cause distended lungs & cardiac septal shift, can cause alveolar distention, venous return is impeded, surfactant production may be impaired
What is the goal of protective mechanical ventilation? minimize injury to the lung
Large Vt and high FiO2 do not improve gas exchange. High FiO2 can actually do what? accelerate atelectasis formation
Spontaneous ventilation preserves ______ __________ lung mechanics
How does the volume control setting on the ventilator work? inspiration is terminated when preset volume is reached
How does the pressure control setting on the ventilator work? inspiration is terminated when preset pressure is reached
Does fresh gas flow affect Vt? yes; unless using fresh gas flow compensators (FGF decoupling) to maintain accurate Vt (new vents have this)
Describe what happens to ascending (standing) bellows during a ventilatory cycle they ascend (fill) during expiration and descend (empty) during inspiration
What is an advantage of ascending bellows? they will not fill in the event of disconnect, so it is very easy to detect
Describe what happens to descending (hanging) bellows during a ventilatory cycle they ascend (empty) during inspiration and descend (fill) during expiration
What is an advantage of descending bellows? provides compactness and ease of sterilization of entire breathing circuit
What is a disadvantage of descending bellows? harder to detect ventilator disconnect because bellows will fill with room air due to gravity
The higher the I:E ratio, the __________ the inspiratory pressure. Why? lower; because the breath is delivered over a longer amount of time
The lower the I:E ratio, the __________ the inspiratory pressure. Why? higher; because the breath is delivered over a shorter amount of time
How does rate effect the I:E ratio? decreasing rate will decrease pressure and flow (longer breathing cycle); increasing rate will increase pressure and flow (shorter breathing cycle)
How does the I:E ratio effect ETCO2? increasing I:E ratio = shorter expiratory phase & less ETCO2 evacuated; decreasing I:E ratio = longer expiratory phase & more ETCO2 evacuated
Correct application of PEEP is just above ________ Pflex; this maintains an open lung
Recommended Vt is __ - __ ml/kg of predicted body weight (ideal body weight), but not > ___ ml/kg 6 - 8 ml/kg; not greater than 10 ml/kg
How do smaller tidal volumes reduce alveolar ventilation? smaller Vt will blow off enough ETCO2 (ventilation) but alveoli will be unexpanded and will partially or completely collapse
Minute ventilation = __________ x __________ tidal volume x frequency
Increasing respiratory rate and decreasing tidal volume can produce the same minute ventilation, but it cannot account for ______ ________ dead space
How much PEEP does the weight of the ascending bellows add? 2 - 3 cmH2O of PEEP (intrinsic PEEP)
Circuit disconnect will cause bellows to immediately deflate, but a small circuit leak will cause what with regard to bellows? Small circuit leaks will cause small amounts of tidal volume to slowly leak with each cycle = a gradual descending over minutes
What is the key indication of how well we are ventilating the patient? measure of ETCO2
What is static compliance? occurs during times without gas flows, such as during inspiratory pause or at end of exhalation
Static compliance is compliance without the effects of what? airway resistance
How do you measure static compliance? measured using plateau pressure (end inhalation prior to exhalation)
Plateau pressure is always ____ than peak pressure (dynamic compliance) less
Static compliance is mostly constant unless what changes? lung compliance
What is dynamic compliance? occurs during times of gas flow, during active inspiration
How is dynamic compliance measured? using peak pressure
Dynamic compliance = ____________ + ______________ lung compliance + airway resistance (a negative number)
True or False: dynamic compliance (measured using peak pressure) can change from breath to breath while lung compliance mostly remains unchanged True
Volume control ventilation is best for what patient population? patients with no respiratory effort and little expected change in airway resistance and intrathoracic pressure
In volume control ventilation, increasing the rate also increases what? the minute ventilation
In volume control ventilation, what factors can effect PiP? compliance, secretions, kinks in the ETT
In pressure control ventilation, Vt can vary breath-to-breath depending on what? airway resistance and other factors
When does expiration occur in pressure control ventilation? when inspiratory time and airway pressures are reached
When is pressure control ventilation useful? when high PiPs are not appropriate and when compliance is low
What type of patients cannot handle high PiPs? patients with LMAs in, patients with emphysema, neonates & children
What types of conditions or situations could cause a patient to have low compliance? laparoscopic surgery (r/t insufflation of abdomen), pregnancy, morbid obesity, ARDS, chest rigidity related to opioid use
List some usual initial ventilatory settings Respiratory rate 8-12, Vt 6-8 ml/kg of ideal body weight, PEEP of 5, FiO2 40 - 50%, I:E ratio of 1:2
PEEP can decrease what 3 things? CO, SBP, and VR
What 3 things account for the difference between set and delivered Vt? circuit compliance (distensibility), gas sampling, gas compression
Deadspace is approximately ____. 150 mls
What is the most efficient way to improve ventilation? raising tidal volume
What is the most efficient way to increase pulmonary minute ventilation? increase tidal volume
If CO2 production is unchanged and alveolar ventilation is cut in half the alveolar CO2 (PACO2) will do what? double
Inadequate O2 delivery to alveoli will cause a(n) ________ in PAO2 decrease
Inadequate CO2 removal will cause a(n) ________ in PACO2 increase
PA representation of what's in the alveoli
Pa representation of what's in the arterioles
PAO2 = ________ x ____________ FiO2 x PACO2
FiO2 = ____________ x _______________ barometric pressure x water vapor pressure
I:E ratio reflects the inspiratory time in relation to the expiratory time
What is I:E ratio is determined by? respiratory rate and inspiratory flow
The higher the I:E ratio, the ________ the inspiratory time greater
The higher the I:E ratio, the ________ the inspiratory pressures lower
How does decreasing the rate at a constant I:E ratio affect inspiratory pressure? inspiratory pressure will decrease
What is the effect of increasing fresh gas flow on Vt and Vm? On PiPs? increases Vt, increases Vm, increases PiP (in a machine without FGF decoupling)
If the Vm remains the same, but the rate is decreased, what effect will this have on Vt? On PiP? Vt will be increased; PiP will be increased
If the Vm is decreased but the rate remains unchanged, what will happen to the Vt? Vt will decrease
What happens to the Vt if the rate increases but the Vm remains the same? Vt will decrease
What is pressure support ventilation? Similar to CPAP, patient's own respiratory effort triggers ventilator to deliver pressure supported breath
What is the purpose of the 5 - 10 cmH2O of pressure in pressure support ventilation mode? helps overcome the negative inspiratory pressure resistance of ETT, circuit, and filters
What is sensitivity as it relates to pressure support ventilation? The threshold of flow needed to trigger the ventilator to deliver a pressure supported breath
____ sensitivity is 5-10 L/min low
____ sensitivity is 2 L/min high
_________ the sensitivity means that the ventilator will sense a smaller effort from the patient and deliver a pressure supported breath Increasing
_________ the sensitivity means that the ventilator will require more of an effort from the patient to initiate a pressure supported breath Decreasing
In pressure support ventilation, _________ _____ is determined by the patient. respiratory rate
What mode of ventilation is used in conduction with IMV and SIMV? pressure support ventilation
When does expiration begin in pressure support ventilation? when flow decreases
Only __________ pressure is set in pressure support ventilation inspiratory
What are 4 indications for pressure support ventilation? to augment Vt in spontaneously breathing patients, to decrease WOB & increase pt comfort, for weak inspiratory effort, for obstructed airway breathing
What is SIMV ventilation? Rate is set as well as volume. Patient allowed to initiate breath with pressure support. Pt's efforts synchronized with ventilator. If pt does not initiate breath in set time, ventilator will still deliver
How does the ventilator sense the patient's effort in SIMV ventilation? Vent senses negative pressure created by diaphragm, it then delivers pressure supported breath
What are some advantages of SIMV? "backup" ventilation if pt respiratory rate decreases, allows spontaneous breaths, patient control over vent, ideal with pt too deep to maintain normal CO2 level
What is a V/Q mismatch? ventilation without perfusion
What is an intrapulmonary shunt? perfusion without ventilation
In ABGs, what component(s) is an assessment of oxygenation? PaO2 and Oxyhemoglobin Sat
In ABGs, what component is an assessment of ventilation? PaCO2
In ABGs, what components are an assessment of acid-base status? pH, bicarb, base excess
What is hypoxemia? decreased blood oxygen levels resulting from decreased delivery of oxygen from atmosphere to the blood
What is hypoxia? decreased delivery of oxygen to the tissues
What are the 5 types of hypoxia? hypoxemic hypoxia, anemic hypoxia, circulatory hypoxia, histiocystic hypoxia, affinity hypoxia
Decreased RBCs, carboxyhemoglobin, methemoglobin and hemoglobinopathies are all examples of which type of hypoxia? anemic hypoxia
Cyanide poisoning is an example of which type of hypoxia? histiocystic hypoxia (histotoxic)
A decreased release of oxygen from hemoglobin to the tissues (shift of curve) is an example of which type of hypoxia? affinity hypoxia
Decreased CO and decreased local perfusion would cause which type of hypoxia? circulatory hypoxia
Low inspired oxygen r/t high altitude, hypoventilation, V/Q mismatch and intrapulmonary shunt can all lead to which type of hypoxia? hypoxemic hypoxia
How is ETCO2 measured? by infrared absorption; CO2 is measured & wave form is created over time using CO2 value
What are 2 methods of ETCO2 gas sampling? Mainstream (non diverting or flow through) and Sidestream (diverting or aspiration)
How is ETCO2 measured in mainstream sampling? measurement chamber is placed directly at airway
How is ETCO2 measured in sidestream sampling? gas continuously suctioned from breathing circuit into sample cell within the monitor
Which method of gas sampling can be used in non intubated patients? sidestream sampling; thru special nasal cannula or adapter added to normal nasal cannula
List some conditions that cause an increase in the production of CO2 & delivery to tissues fever, physical activity, seizures, sepsis, hyperthyroidism, trauma & burns, high carb diet
List some conditions that cause a decrease in CO2 production & delivery to tissues hypothyroidism, hypothermia, paralysis, motionlessness, pulmonary hypopurfusion, cardiac arrest, PE, hemorrhage, hypotension, right to left pulmonary shunt
What causes a decrease in the elimination of CO2? hypoventilation, COPD, respiratory center depression
What causes an increase in the elimination of CO2? hyperventilation
In general, what 2 things affect the elimination or evacuation of CO2? cardiac status and ventilator setting
In general, what affects the production of CO2? patient metabolic state
What are some factors that could result in erroneously low CO2 readings? ventilator disconnect, esophageal intubation, complete airway obstruction, poor sampling, leak around ETT cuff
How does pulse oximetry work? dual wavelengths of light (660 nm & 940 nm) pass through tissues and vascular beds via LED and absorb the light; ratio of absorption calculated at each wavelength
What 3 factors would cause pulse oximetry to read falsely high? carboxyhemoglobin, methemoglobin when SaO2 < 85%, ambient fluorescent light
What could cause pulse oximetry to read falsely low? methemoglobin when SaO2 > 85%, bad fitting probe, low SpO2/SaO2, poor perfusion, anemia (hct < 24%), hypoxemia, IV methylene blue dye, excessive motion, blue nail polish
The correct application of PEEP is just above ________, which maintains an "open lung" Pflex
What are 5 clinical conditions in which a precordial stethoscope could identify a problem prior to alternative anesthesia monitoring? Apnea, air embolism, bronchospasm/aspiration, congestive heart failure, arrhythmias/cardiac arrest
What would you hear through your precordial stethoscope during bronchospasm or aspiration? Wheezing
What would you hear through your precordial stethoscope in a patient with congestive heart failure? S3 gallop rhythm & rales
What would you hear through your precordial stethoscope in a patient with an air embolism? sudden appearance of new murmur (mill wheel murmur)
What monitoring findings would you see in a patient with congestive heart failure? increase in airway pressure, elevated CVP, elevated PAP, elevated PAOP
What monitoring findings would you see in a patient with an air embolism? decrease in ETCO2, increased CVP, change in capnogram, increase in airway pressure
What monitoring findings would you see in a patient with bronchospasm or aspiration? change in capnogram, increase in airway pressure
How do ventilation and oxygenation correlate? an increase in CO2 will decrease PaO2
How is ETCO2 measured? measured during ventilatory cycle by infrared absorption; waveform created over time using CO2 value
What are 2 methods of gas sampling in intubated patients? mainstream sampling & side stream sampling
How does mainstream sampling work? measures CO2 passing through an adapter placed in the breathing circuit
How does side stream sampling work? continuously suctions gas from breathing circuit into sample cell within the monitor
What method of gas sampling can be used to monitor ETCO2 in non intubated patients? How does it work? Side stream; sampling line attached to nasal cannula
What are some examples of when you would need to monitor ETCO2 in non intubated patients? during conscious sedation procedures like colonoscopy or endoscopy; AA and AANA mandated that we measure this in these patients in 2012 (standard of care)
How will the capnograph waveform differ in non intubated patients? no real plateau will be evident because of ambient air contamination; will look more like a camel's hump
What does phase I of the capnograph waveform represent? What does it look like? dead space expiration; flat line because no perfusion occurs in dead space
What does phase II of the capnograph waveform represent? What does it look like? mixed dead space & alveolar expiration; upward slanting line
What does phase III of the capnograph waveform represent? What does it look like? alveolar gas expiration; plateau
What does phase IV of the capnograph waveform represent? What does it look like? where end tidal CO2 is actually measured because it is the end of expiration; small upswing of the end of the plateau of phase III
What does phase 0 represent on the capnograph waveform? What does it look like? inspiration; downward slanting line
What capnograph waveform should you see after intubation in order to ensure that the ETT is in the lung rather than the esophagus? 3 equal height waveforms at 30 - 40 mmHg CO2
What would the capnograph waveform look like if the ETT is in the esophagus? small waveforms the decrease in size with no plateau
What does a curare wave look like and what does it represent? a dip in the end expiratory plateau; represent diaphragmatic movement - can be seen in patients recovering from neuromuscular blockade
If a surgeon pushes on the diaphragm or the abdominal cavity (displacing the diaphragm), what capnograph waveform will you see? curare waveform
What would an upward shift in the baseline of a capnograph waveform indicate? What would you check? increasing inspired CO2 content; check unidirectional valves, soda lime, is patient stacking breaths?
What does a capnograph waveform look like in a patient with restrictive pulmonary disease like pulmonary fibrosis? slanted waveform at phase 0 (difficulty with inspiration)
What does a capnograph waveform look like in a patient with obstructive pulmonary disease like COPD or asthma? increased or slanted phase II & phase III means patient is having trouble expiring
What do cardiogenic oscillations look like on a capnograph waveform? What patient population would you typically see this in? small pulsations seen during plateau (phase III); usually seen pediatric patients
In general what kind of factors would cause an increase in PiP and Plateau Pressure? a decrease in pulmonary compliance (static compliance)
What are some examples of decreased pulmonary compliance (static compliance)? pulmonary edema, trendelenberg position, pleural effusion, ascites, abdominal packing, peritoneal gas insufflation, tension pneumothorax, endobronchial intubation
In general what kind of factors would cause in increase in PiP but not Plateau Pressure? an increase in airway resistance (dynamic compliance)
What are some examples of increased airway resistance (dynamic compliance)? kinked ETT, bronchospasm, secretions, foreign body aspiration, airway compression, ETT cuff herniation
Pressure volume loops are an indication of what? lung compliance (distensibility)
Pressure volume loops graph a change in volume vs. a change in pressure. Which value is on the X axis and which is on the Y axis? Volume is graphed on the Y axis and pressure is graphed on the X axis
How is the slope of the loop in a pressure volume loop indicative of lung compliance? fatter slope = decreased compliance (higher pressure with less volume); steeper slope = increased compliance (higher volume with less pressure)
Pressure volume loops move counter clockwise during _____________ positive pressure ventilation
Pressure volume loops move clockwise during ______________ spontaneous respiration
Flow volume loops are an indication of what? pulmonary resistance
Flow volume loops graph a change in flow vs. a change in volume. Which value is on the X axis and which is on the Y axis? Volume is on the X axis and Flow is on the Y axis
What is the normal shape of a flow volume loop? upside down ice cream cone
What is the shape of a flow volume loop in a patient with restrictive lung disease? normal shape on a smaller scale; smaller lung volume and reduced flows
What is the shape of a flow volume loop in a patient with obstructive lung disease? shape is caved in and wider; larger lung volumes with reduced flows
Created by: Mary Beth