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127 Cards in this Set
- Front
- Back
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What is the effect of high levels of CO2 on CBF?
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Cerebral Steal syndrome: blood vessels vasodilate and they are unable to direct blood flow to ischemic areas
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What is the effect of low levels of CO2 on CBF
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the blood vessels vasoconstrict and if there is an ischemic area, those vessels are able to dilate -- Inverse steal
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Why does the decrease in CO2 with hyperventilation only occur for 6-8 hours?
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b/c there is active transport of bicarbonate ions form the CSF to the blood stream to normalize the pH
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For every 1-2 mm Hg increase in CO2, what happens to CBF?
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CBF increase 1-2 ml/100gm/min
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How does BP effect CBF?
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BP 50-150 = CBF is autoreulated
BP < 50 = CBF decreases BP > 150 = CBF increases |
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what does hypoxemia (PaO2 < 50) do to CBF?
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increases it
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What are the 2 components of intracranial compliance?
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1. Shunting of blood from intracranial blood vessels to extracranial blood vessels
2. shunting of CSF from the brain ot the arachnoid space. |
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How does HTN lead to edema in the brain?
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Causes High Capillary hydrostatic pressure and fluid leaks out into the brain
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What are the anesthetics that should be avoided in neurosurgery d/t potential increase in Cerebral metaabolic rate (CMR)?
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Ketamine
Nitrous (when used alone) Enflurane (potential for sz) |
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Why do you avoid Etomidate in neurosurgery?
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B/c it suppresses the adrenal corticol response and these pt have brain swelling, so need cortisol
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What are the factors that can increased CMR causing increase CBF?
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Arousal/pain
Seizures hyperthermia Certain anesthetics: nitrous, ketamine, enflurane |
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List the factors that influence CBF
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PaO2 (increased CBF with hypoxia)
PCO2 (increased CO2 cause vasodilation) Cerebral metabolic Rate Blood pressure (autoregualtion) Vasoactive Drugs Blood viscosity neurogenic pathways |
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What are some things that can cause increase airway pressures (increased intrathoracic pressures)
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airway obstruction
kinked ETT coughing, bucking bronchospasm pneumothorax |
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Are most tumors frontal or posterior?
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frontal (supratentorial)
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What is the goal of anesthesia in supratentorial tumors?
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reduced intracranial volume: control ICP ("slack brain")
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What is the dose of mannitol in the treatment of increased ICP?
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0.25-1 Gm/kg
Given over 10 minutes Duration of Action is 2 hours |
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What is the most important thing you can do on induction with a pt with high ICP?
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**Blunt the stress of intubation**-- deepen anesthetic
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What is the major risk when a surgical site is 5cm above the level of the right atrium?
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Air embolism
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What is macroglossia?
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swelling of the tongue; can occur with posterior fossa or supratentorial brain surgery d/t neck flexion and ETT compressing the tongue
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List the considerations relevant to posterior fossa procedure
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1. Hemodynamic effects of the sitting postision 9transduce BP at level of the head
2. Venous air embolism 3. Paradoxic air embolism 4. Hemodynamic effects of brain-stem or cranial nerve manipulation 5. Qudriplegia 6. Macroglossia 7. Pneumocephalus |
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What is the postop treatment used to avoid vasospasm in brain aneurysm clipping?
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HHH
Hypervolemia hypertension Hemodilution |
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What is cushing's triad and what is it a sign of?
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HTN, Bradycardia, Irregular RR
very high ICP |
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pack years smoked is directly related to what?
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changes in the respiratory gas flow and closing capacity
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what kind of COPD pt have less sensitivity to CO2 (bronchitis or emphysema)
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Bronchitis: blue bloaters: high CO2 and nl pH
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what is the normal Residual volume to total lung capacity ration (RV:TLC)
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1:6
if it is greater than 50%-- pt is at high risk |
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What is the expected paO2 with 27.5% shunt
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150 mmHg
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When doing preop testing for thoraci surgery, what result on ABG's is linked to increased postoperative risk
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Hypercapnea on Room Air
Bonchitis: less sensitivity to CO2 (increased CO2 & nl pH) Emphysema: retain sensitivity to CO2 |
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spirometry FEV1 < what? is indicator of increased postoperative risk
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FEV1 < 50% of FVC or
FEV1 < 2 Liters |
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On pretesting spirometry what result for Minute Breathing capacity is indicator of Increased postoperative risk?
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MBC < 50% of predicted
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What is the RV/TLC result on spirometry that indicates increased posoperative risk?
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RV/TLC > 50%
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With Obstructive Lung Disease, what is the problem on the flow volume loop curve?
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Abnormal Expiration: slow and unable to exhale full volume (scooped out curve)
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What result on ABG's is linked to increased postoperative risk
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Hypercapnea on Room Air
Bonchitis: less sensitivity to CO2 (increased CO2 & nl pH) Emphysema: retain sensitivity to CO2 |
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spirometry FEV1 < what? is indicator of increased postoperative risk
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FEV1 < 50% of FVC or
FEV1 < 2 Liters |
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On pretesting spirometry what result for Minute Breathing capacity is indicator of Increased postoperative risk?
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MBC < 50% of predicted
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What is the RV/TLC result on spirometry that indicates increased posoperative risk?
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RV/TLC > 50%
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With Obstructive Lung Disease, what is the problem on the flow volume loop curve?
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Abnormal Expiration: slow and unable to exhale full volume (scooped out curve)
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What is th normal Residual volume to Total lung capacity ratio (RV: TLC)?
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1:6 --Very Low
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what is FEV1 a direct indicator of?
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Airway obstruction
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What FEV1 value is an Absolute contraindicaiton to lung resection
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FEV1 < 800 ml for Average 70 kg pt
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What 2 times are pt's most at risk for cardiac ishemia during thoracic surgery?
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intraop
3 days postop |
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What are the 3 main Reasons for postop complications in thoracic surgery?
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Preop: Extent of underlying pulmonary disease
Intraop: lateral position-- Dependent lung edema Postop: PNA and atelectasis due to not deep breathing and coughing |
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What are the 2 predictors for cardiac ischmia?
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Hypotension and tachycardia
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What is the problem in pts with restrictive lung disease?
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Compliance: low lung volume
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What is functional Peripheral vascular disease?
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caused by Vasopspasms
example: Raynaud's triggered by emotional stress and smoking |
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What is organic Peripheral vascular disease
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Caused by structure changes int he vessel; INFLAMMATION (vasculitis) and tissue damage (atherosclerosis)
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What is the #1 killer for women?
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heart disease
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Define peripheral Vascular disease
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disease of blood vessels outside of the heart and brain
can be categorized as organic or functional |
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What are the causes atherosclerosis (4)
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Hypercholesteremia
HTN, shearing from vessel wall stress Tobaco smoke Diabetes |
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Define Atherosclerosis
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Athero = paste
sclerosis = hardness the process in which deposits of fatty substances, cholesterol, cellular waste products, calcium, smooth muscle cells, connective tissue and other products build up in the lumen of the artery build up is referred to as plaque (can be stable or unstable) |
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What makes the process of atherosclerosis quicken
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have a lot of risk factors (smoking, HTN, obesity, etc.)
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What does smoking do to the vasculature?
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Increases platelet activity and causes vasospasm
Inhibits Nitric oxide and inhibits the function of the endothelial lining: less compliant, more likely to vasospasm and more likely to adhere fibrin and other waste molecules |
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what it the definition of HTN
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Systolic > 140
Diastolic > 90 Causes turbulent flow; stress on th vessels |
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How does DM affect the vasculature
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Chemical rxn b/t the proteins and sugars that causes endothelial lining to be stiff and dysfunctional
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What does obesity do to vasculature
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more LDL and more inflammatory mediators, more likely to have LDL adhere to the endothelial lining
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What is the hallmark in the pathophysiology of atherosclerosis
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Plaque formation
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what is an unstable plaque
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have a thin cap and thick lipid core (ruptur is more common than occlusion)
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Are coronary artery plaques stable or unstable?
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Unstable
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are Carotid plaques stable or unstable
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unstable
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what are the most common sites for plaque lesions?
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Areas of Turbulent Flow (bifurcations):
coronary arteries carotid bifurcation abdominal aorta illiac arteries |
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What are the 2 key contributing factors to aneurysm formation?
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HTN and Atherosclerosis
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What vessel is most susceptible to aneurysms and why?
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aorta
due to high constant stress to vessel wall and absence of penetrating vasa vasorium in adventitial laayer |
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What is vasculitits
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inflammation of blood vessel which includes vieins, arteries and capillaries
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What are the signs and symptoms of vasculitis
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fever
fatigue weight loss muscle and joint pain (different from claudication) loss of appetite |
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What is the most common vasculitis in the US
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Temporal Arteritis
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What is most important preop consideration for patients having vascular surgery?
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Optimization of cardiac risk Caridac testing beyond EKG
< 10% of pt's undergoing vascular surgery have normal coronaries |
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What are most important intraop considerations that should be done during vascular surgery
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Beta blockers
Forced air warming ICU monitoring |
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**What is the most common cause of peroperative death?
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Myocardial Ischemia
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What do you see on a TEE monitor during ischemia?
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ventricular wall thickening
-detect segmental wall changes |
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What are the advantages in GA for peripheral vascular surgery vs. regional
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1. pateints can remain on IV anticoagulants without interruption
2. Able to graft upper extremities (hard to do regional for high surgical procedure) |
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What are the disadvantages to GA in vascular surgery (vs regional)?
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1. produces a hypercoagulable sstate
2. Increased post catecholamines (extubation) 3. may pose ventilatory challenges postop (unable to extubate, decreased ventilatiaon due to decrease MS) |
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What vascular procedure is intermediate risk?
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carotid endarterectomy
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What are the goals of anesthsia in carotid endarterectomy?
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1. Optimize cerebral perfusion in patients iwth high prbability of CAD
2. Minimize CVA risk |
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Are most strokes Embolic or stenotic
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90% of strokes are embolic
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Denervation of what will blunt the ventilatory response to hypoxemia?
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denervation of the carotid bodies
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What are the 3 nerves of concern during a carotid endarterectomy?
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Vagus nerve
Hypoglosal nerve Glossopharyngeal nerve |
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What does the carotid sinus do?
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reacts to arterial pressure
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Whatr are the 2 most important arteries the supply the cicle of willis?
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Basilar artery
Internal carotids |
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How long should clamp time be during a carotid endarectomy
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< 30 minutes
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where do you want your BP to be during a carotid endarectomy?
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Mean 20-30% above baseline
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where do yo want CO2 to be during a carotid endartectomy
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maintain normocapnia
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Where do you want HR when graft being placed in carotid Endarectomy?
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low
have nitroglycerin ready |
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What will happen during Carotid endarectomy surgery when carotid sinuses stimulated?
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causes activation of barorecpetor reflexes = hypotension and bradycardia
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What things increase a pt's risk of poor neurologic outcomes with Carotid endarectocmy surgery
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-poor collateral flow
-contralateral carotid occlusion -renal insufficiency -poorly controlled HTN -h/o CABG -decreased consciousness or change in MS preop -active neurologic process (h/o stroke) |
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What are type A Anuerysms?
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Ascending orta to arotic arch
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What are type B aneurysms
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Proximal descending aorta and ends distally
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What is reactive hyperemia
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Transient increase in blood flow after prolonged ischemia
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when unclamping in aorta bifemoral aneurysm repair, how is it done?
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one leg at a time
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What is best indicator of postop renal function in AAA repair: u/o, volume status, or preop renal function
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preop renal function and volume status are best indicators of postop renal function
keep euvolemic |
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What do the mediators released during clamping do to the pulmonary vasculature?
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make it very permeable: pulmonary hypertension and pulmonary edema
pt may need to stay intubated postop |
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Where does the artery of adamkowitz joins the anterior spinal artery?
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between T8 and T12 in 75% of population and b/t L1 and L2 in 10%
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When is hypothermia used in AAA repair?
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very high clamps
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Why are barbiturates (thiopental gtt) used sometimes in AAA repair
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For very high clamp
Cerebral protection: decreased CMRO2 to decrease the risk of seizure |
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How long after an epidural is placed can you use IV heparin?
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1 hour
Lovenox is the same |
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What happens if you get a blood tap when placing an epidural for an aortic aneurysm repair
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case is cancelled
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how much does RBF decrease with infrarenal clamp
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40%
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if pt has hypotension >20% below baseline when clamp is placed during AAA repair, what wil happen?
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may become ischemic below the clamp
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List the hemodynamic changes that occur with clamping during an AAA repair
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MAP and SVR Increase
CO decreases (initially) O2 consumption decreases below the clamp Preload may increase (if myocardial dysfunction present) |
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During thoracic surgery, what would poor lung compliance and low exhaled TV be indicators of?
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Malpositioning of the DL tube
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What is normal FEV1 and what does severe dyspnea imply (regarding FEV1)?
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NL is 4 L
implies FEV1 < 1.5L |
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What are 3 things PFTs are used to evaluate
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1. how much lung can be resected without leaving pt a pullmonary cripple
2. Evaluate need for ventilatory support postop 3. Evaluate if bronchodilators are helpful |
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What type of obstruction to flow does a mediastinal mass cause?
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inspiratory obstruction -- Extrathoracic (with inspiration, the postiitve pressure of the mass tends to collapse the airway)
very dangerous to anesthetize these pt's b/c the mass will cause |
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If there is restricted flow on expiration and inspiration of a flow volume loop, what does this indicate?
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Fixed Obstruction (tracheal stenosis)
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if you have a Left DL tube and doing surgery on the left, which side do you clamp to deflate the left lung?
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Bronchial
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If have a left DL tube in and doing surgery on Right, what side do you clamp to deflate the right?
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Tracheal
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What type of ventilation should be used for one lung ventialtion?
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Pressure Control to make sure PIPs stay below 30
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What does hypocapnea do to pulmonary vascular resistance?
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Increases it (this would be bad in one lung ventialtion, so avoid hyperventilating paient)
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List 3 reasons hypoxia occurs during onel lung ventilation
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1. Shunt
2. Pressure: edema or pushing down from from the surgeon, instruments, or mediastinum 3. PEEP: causes alveoli to expand, so blood moves to nondependent lung and does not recieve O2 |
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When using volatiles during thoracic surgery, what MAC do you maintain in order to decreased amount of shunt they cause?
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<1 MAC;
If use 1 MAC, the shunt will be increased by 4% |
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How do vasodilators affect HPV?
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They decreased HPV b/c if PA pressures are too low, blood flow cannot be re-directed
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List steps to take if severe hypoxemia occurs during one lung ventilation
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1. check postition of tube with Fiberoptic scope
2. Check hemodynamic status 3. Nondependnet lung CPAP 4. Dependnet lung PEEP 5. Intermittent two-lung ventilation 6. Clamp PA asap (for pneumonectomy) |
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What is the greatest risk with one lung ventilation?
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Hypoxemia
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According to DeBakey classifiction of Aorta Aneurysm, who is at most risk of spinal cord and renal injury after repair
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IIIB-- involves both thoracic and abdominal aorta (entire aorta accept the ascending part)
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According to Crawford Classification of Aortic aneurysm who is at most risk of paraplegia and renal failure after repair
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Type II -- descending aorta and most or all of the abdominal aorta
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What DeBakey classification of aortic aneurysms is confined to the ascending aorta
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Type II
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During an Endovascular AAA repair is there complete intrruption of aortic flow?
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NO, circulation to extremity may be reduced, but is never stoppped completely.
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According to DeBakey classifiction of Aorta Aneurysm, who is at most risk of spinal cord and renal injury after repair
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IIIB-- involves both thoracic and abdominal aorta (entire aorta accept the ascending part)
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According to Crawford Classification of Aortic aneurysm who is at most risk of paraplegia and renal failure after repair
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Type II -- descending aorta and most or all of the abdominal aorta
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What DeBakey classification of aortic aneurysms is confined to the ascending aorta
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Type II
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During an Endovascular AAA repair is there complete intrruption of aortic flow?
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NO, circulation to extremity may be reduced, but is never stoppped completely.
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What size catheter is used for endovascular AAA repair
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5-6 Fr. sheath
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If pt has Increaed WBC and fever 24-48 postop for Endovascular AAA repair, what is most likley cause?
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Reaction to graft material (usually benign)
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What is overall goal for postop care with vascular surgery
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Control adrenergic stress related to surgery:
Pain control (epidural, narcotics, dexmetatomidine) Maintain Normothermia monitor volume status monitor ventilatory status (normocapnea) maintain hemodynamic stability |
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when do most cardiac complications occur with vascular surgery
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Postoperatively -- end of case is very important
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What does a single lung test tell you when preop testing for thoracic surgery?
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Predicts the function of the lung stissue that would remain after resection
IV Isotope injection: evaluates the perfusion to each lung Isotope Inhalation:: evaluates the ventilation to each lung |
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What results on a single lung test Isotope injection and Inhalation predict very high risk for thoracic surgery
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Predicted postop FEV1 < 800 ml
>70% blood flow goes to diseased lung |
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What prop test result will make pt an absolute contraindication for thoracic surgery
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FEV1 < 800 ml (70 kg person)
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A VC of < 50% of predicted or < 2 L indicates what about postop complications and mortality for thoracic surgery?
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30% chance of complications
10% risk of postop mortality |
