Anesthesia Principles and Practice I: Lecture 5 - Vascular Access

Question 1

What is the primary purpose of an intravenous line (IV)?

Answer 1

To administer volume, medications, and infusions. (pressor therapy, etc.)

Meds skip first pass metabolism

Fluid/blood loss

Question 2

What does NPO stand for in a medical context?

Answer 2

Non per os.

Question 3

What are the types of IV fluids?

Answer 3

• Crystalloid
• Colloid
• Blood Products

Question 4

What percentage of body weight is fluid in adults?

Answer 4

60%.

Total Body Water varies by age
Pre-term 80-85%
Term 75%
Infant 65%
Adult Male- 60%
Adult female- 50%

Question 5

What is osmolality?

Answer 5

Osmolality - count of the total number of particles in a solution and is equal to the sum of the molalities of all the solutes present in that solution (osmol/kg)
Hyperosmotic
Hypoosmotic

Osmolality - the concentration of an osmotic solution per 1000 grams of solvent

Osmolarity – the concentration of osmotic solution per liter of fluid

Question 6

Define hyperosmotic solution.

Answer 6

A solution having a higher concentration of solute particles per unit volume than a comparison solution.

Question 7

What is the normal osmolality of plasma?

Answer 7

285 mOsm/L.

Ions produce osmotic pressures (mOsm/L) across cell membranes, but not capillary membranes.

Large protein molecules produce colloid osmotic pressures (oncotic pressures) across capillary membranes. Oncotic pressure (mmHg)

Normal = 28 mmHg

Question 8

What is the normal oncotic pressure in capillaries?

Answer 8

28 mmHg.

Question 9

Solution Adjectives

Answer 9

Tonicity - Frequently used in place of osmotic pressure or tension, is related to the number of particles found in solution.

Isotonic - Of equal tension. Denoting a solution having the same tonicity as another solution with which it is compared.

Hypertonic - Having a higher concentration of solute particles per unit volume than a comparison solution, regardless of kinds of particles. A solution in which cells shrink due to efflux of water.

Hypotonic - Having a lower concentration of solute particles per unit volume than a comparison solution, regardless of kinds of particles. A solution in which cells expand due to influx of water.

Question 10

What does isotonic mean?

Answer 10

Of equal tension; having the same tonicity as another solution.

This is why we never give Sterile Water IV. Only solutions with similar tonicity to blood.

Lyses Red Blood cells leads to Hemolytic anemia

Can cause kidney failure and death

Question 11

Fill in the blank: We never give _______ IV.

Answer 11

Sterile Water.

Question 12

What are the normal ranges for sodium (Na+) in mEq/L?

Answer 12

135-145 mEq/L.

Question 13

Equivalents

Answer 13

Question 14

Normal Sodium and Osmolality

Answer 14

Normal saline preferred for neuro cases.
Hypotonic LR can worsen edema.

Question 15

IV Admin Tidbits

Answer 15

IV fluid tonicity dictates peripheral/central admin. Hypotonic and hypertonic solutions may be infused in small volumes and into large vessels, where dilution and distribution are rapid. Peripheral admin can cause extreme pain.

900 mOsm/L is upper limit for peripheral IV. Greater than that causes irritation of the intimaphlebitis

Very hypotonic solutions (1/4 NS/Sterile Water) cause cells to swell and burst.

Question 16

What is the 4-2-1 rule for fluid maintenance?

Answer 16

• 4 ml/kg/hr for the first 10 kg
• 2 ml/kg/hr for the second 10 kg
• 1 ml/kg/hr for all weight >20 kg

80 kg patient
4ml/kg/hr10kg = 40 ml/hr
2ml/kg/hr10kg = 20 ml/hr
1ml/kg/hr*60kg = 60 ml/hr
80kg = 120 ml/hr.
8 hr deficit = 960 ml deficit

Can also do weight in kg +40 in patients over 20 kg

Question 17

Perioperative “insensible” fluid loss

Answer 17

2-4 ml/kg/hr minor surgery robotic/laparoscopic surgery/hernia repair

4-6 ml/kg/hr moderate surgery

6-10 ml/kg/hr major surgery, open abdomen/trauma etc

If they are obese, you will adjust for IBW

Question 18

Fluid Replacement

Answer 18

Question 19

Goals of Fluid Resuscitation

Answer 19

Establish or maintain adequate end organ perfusion pressure

Establish or maintain O2 transport to metabolically active tissues

Periop Fluid therapy replaces
Preop-surgical deficit
Surgical losses
Insensible losses

Question 20

Crystalloids

Answer 20

Aqueous solution of low MW ions with or without glucose

Advantages- Cheap, replaces third space loss*, promote urinary flow

Examples include Normal Saline, Lactated Ringers, D5LR (lactated ringers in 5% Dextrose), Plasmalyte

Disadvantages- More likely to cause peripheral and pulmonary edema

3cc crystalloid for every cc EBL

Intravascular half-life of 20-30 mins

Question 21

Types of Crystalloid Solutions

Answer 21

Lactated Ringers
Hypotonic (273 mOsm/L)
Lowers Na level (130 mEq/L)

N.S. (0.9% NaCl)
Treatment for Hypochloremic metabolic alkalosis
PRBC dilution

D5W & D5NS
Replace pure H20 deficit
Maintenance fluid pt w/Na restrictions

3% and 7.5% NaCl
Severe hyponatremia or hypovolemic shock
Infused < 100ml/hr – Central pontine myelinolysis if infused too fast

Question 22

Crystalloid Distribution

Answer 22

D5W can go through cells and vessels

Question 23

Colloids

Answer 23

Aqueous solution of high molecular weight substances

Same volume replacement as EBL 1:1

Maintain plasma oncotic pressure, larger % stays intravascular than crystalloid

Albumin (5 and 25%), Hextend, Hespan

Disadvantages
Starches and dextran may cause coagulopathy
Colloids are $$$
Potential for allergic reaction

Question 24

Colloids Stay Longer in Intravascular Longer

Answer 24

Liter of Albumin = liter of intravascular water

Colloids have intravascular half-lives between 3 and 6 hours

Question 25

Overall Fluid Info

Answer 25

Question 26

IV Fluid Comparison

Answer 26

Question 27

What is the estimated blood volume (EBV) for a male patient?

Answer 27

75 mL/kg.

Question 28

PRBC

Answer 28

Transfusion reactions can occur! Give PRBC in cases of active hemorrhage where patient is symptomatic Hypotensive, tachycardic, may see O2 Sats decrease Young patients may tolerate Hb of 5/6 g/dL no problem Cardiac patient may need Hb 10 g/dL Consider preop autologous blood donation, intraoperative blood recovery (cell-saver), deliberate hypotension/pharmacologic agents when indicated

Question 29

Estimated blood volume (EBV) and Allowable blood loss

Answer 29

Normal Hematocrit values Male 42-52% Women 37-47% HgB to Hct = 1:3 typically Smokers will have higher Hct to try and compensate, as will a healthy individual at altitude Acceptable Blood Loss = [EBV * (Hi-Hf)]/Hi EBV = estimated blood volume Hi = initial hemoglobin Hf = final hemoglobin Preemie: 95 mL/kg Newborn: 85 mL/kg Infant: 80 mL/kg Male: 75 mL/kg Female: 65 mL/kg

Question 30

What is the formula for calculating acceptable blood loss?

Answer 30

EBV * (Hi-Hf) / Hi = Acceptable Blood Loss (Can use Hgb or Hct, need to use all the same (KNOW HOW TO CONVERT BETWEEN THE TWO)) Prior to surgery, what is the estimated blood volume (EBV) of a female patient weighing 60 kg? What is allowable blood loss if her starting HCT is 40%, and 24% is your transfusion trigger? EBV = 60 kg * 65 ml/kg = 3900 ml [3900 * ((40-24)/40) = 1560 ml of EBL could be tolerated in a healthy patient w/o transfusion PRBC Have a HCT of ~60%

Question 31

What are the complications associated with PRBC transfusions?

Answer 31

* Acute hemolytic reaction * Transfusion-related immunomodulation.

Question 32

Blood Compatibility

Answer 32

ABO-Rh typing The most serious reactions to blood transfusion come from incorrect donor/recipient typing (ABO incompatibility) Recipient red cells tested against serum with A & B Antibodies O- is universal donor, AB+ Universal Recipient Duration: < 5 min.

Question 33

Antibody Screen

Answer 33

Question 34

Blood Crossmatch

Answer 34

Donor red cells are mixed with recipient serum Crossmatching confirms ABO and Rh typing, detects antibodies to other blood group systems and detects antibodies in low titers

Question 35

PRBC Pearls

Answer 35

Check PRBC unit against blood slip and patient ID Transfuse through a fluid warmer and a 170 micron filter PRBC preserved with CPDA Citrate, Phosphate, Dextrose, Adenosine Citrate binds calcium- Should give blood with Normal Saline to prevent Ca in LR from binding to Citrate in preservative and agglutinating. K+ concentration increases as blood gets older (cells lyse)

Question 36

PRBC Transfusion Complications

Answer 36

Question 37

Giving Blood is Not Benign

Answer 37

Transfusion-Related Immunomodulation Transfusion is likely to promote inflammation and diminish immunoresponsiveness ↑risk of post-op infection ↑risk of Cancer Recurrence ↑Risk of Mortality

Question 38

Acute hemolytic Reaction

Answer 38

Usually due to misidentification of a patient, blood specimen, or unit of blood Symptoms in awake patients Chills, fever, nausea, chest/flank pain Symptoms in anesthetized patients Rise in temperature, unexplained tachycardia, hypotension, hemoglobinuria, diffuse oozing in the surgical field Treatment: Stop transfusion immediately, notify blood bank Recheck blood slip against patient ID bracelet Draw blood to repeat compatibility testing, obtain coagulation tests, and CBC Insert foley to test urine for hemoglobin Force diuresis with mannitol, IV fluids, and/or loop diuretic

Question 39

Oxyhemoglobin dissociation curve and 2,3 BPG

Answer 39

BPG is a potent modulator of the affinity of hemoglobin for oxygen ↓2,3 BPG causes a shift of the Oxygen hemoglobin dissociation curve to the left, which reduces delivery of oxygen to tissues. (Hemoglobin has an increased affinity for oxygen, doesn’t want to let go of oxygen to tissue beds)

Question 40

When Do we Give Blood?

Answer 40

Like with all things, it depends. Clinical judgement and patient presentation. If they’ve bled a bunch with no end in sight, better to get some blood going that risk poor outcome.

Question 41

What is the recommended transfusion trigger for hemoglobin <6 g/dL?

Answer 41

Transfusion recommended except in exceptional circumstances.

Question 42

Revisiting the transfusion trigger: More restrictive may be better

Answer 42

Hemoglobin <6 g/dL – Transfusion recommended except in exceptional circumstances. Hemoglobin 6 to 7 g/dL – Transfusion generally likely to be indicated. Hemoglobin 7 to 8 g/dL – Transfusion may be appropriate in patients undergoing orthopedic surgery or cardiac surgery, and in those with stable cardiovascular disease, after evaluating the patient’s clinical status. Hemoglobin 8 to 10 g/dL – Transfusion generally not indicated, but should be considered for some populations (eg, those with symptomatic anemia, ongoing bleeding, ACS with ischemia).  Hemoglobin >10 g/dL – Transfusion generally not indicated except in exceptional circumstances.

Question 43

What does dilutional coagulopathy refer to?

Answer 43

Prolongation of PT and aPTT time when blood loss is replaced by fluids lacking clotting proteins. Dilution of clotting proteins will prolong PT and aPTT time when blood loss is replaced by fluids lacking clotting proteins (crystalloid, PRBCs, etc.) Assume ~↓10% in concentration of clotting proteins for every 500 ml of blood loss that is replaced with PRBCs without plasma. Don’t forget to check a cbc for platelets, as these are diluted as well

Question 44

Intraoperative blood salvage: Cell Saver

Answer 44

Benefits: no need for type/cross, no antibodies Increased 2,3 DPG and ATPbetter tissue oxygenation May be accepted by those who refuse blood transfusion Relative contraindications- Malignancy, Local infection, sickle cell/thalassemia.

Question 45

Transfusion recommendations: Platelets

Answer 45

Platelet count <50K Actively bleeding patient Spontaneous bleeding occurs with counts <10k (Bone marrow suppression etc) Platelet apheresis comes from up to 8 donors DO NOT GIVE IN WARMER OR THROUGH BLOOD FILTER OR FILTER!!! Comes in pooled six pack leads to increase platelet count 30-60K in 70 kg patient Does not require same ABO typing but will see greater increase in platelet count if so Scarcity of platelets may not allow for it, ABO compatibility > non-ABO-Compatible ABO identical platelets > ABO compatible platelets > ABO incompatible platelets Small amounts of plasma in In thrombocytopenic patients, increasing hematocrit to ~30% may reduce risk of hemorrhage.

Question 46

What is the function of cryoprecipitate?

Answer 46

Contains clotting factors and is used for bleeding patients.

Question 47

Transfusion recommendations: Cryoprecipitate

Answer 47

Question 48

Transfusion Recommendations: FFP Fresh Frozen Plasma

Answer 48

Contains all plasma proteins and clotting factors (CF) One unit increases Clotting Factors 2-3% SHOULD BE WARMED- you lose point for transfusing cold PRBC and FFP Same infection risk as PRBC Can be given for Antithrombin III deficiency (Heparin activates ATIII as inhibitor of factors Xa and IXa

Question 49

What is the purpose of Fresh Frozen Plasma (FFP)?

Answer 49

Contains all plasma proteins and clotting factors. PLASMA TRANSFUSED MUST BE ABO COMPATIBLE, DOES NOT NEED TO BE RH COMPATIBLE

Question 50

What are the current recommendations for reversal of Warfarin if Same day surgery is required?

Answer 50

Withhold Warfarin Administer 4 factor Prothrombin Complex Concentrate Expensive but can correct a supratherapeutic INR in 30 minutes If not available administer 3 Factor PCC with FFP or FFP alone Administer Vitamin K 10 mg IV May repeat every 12 hrs as needed Takes hours to work as new coagulation factors need to be made in the liver If the procedure can wait 24 hours, Warfarin can be held and Vitamin K given w/o PCC Warfarin Should be held for five days before surgery Warfarin is a Vitamin K Antagonist *In massive transfusion or trauma situations better outcomes have come from 1:1 PRBC:FFP ratio.

Question 51

Where can IV lines be placed on the body?

Answer 51

* Upper Extremities: dorsum of the hand, forearm, antecubital fossa (cephalic, basilic) * Lower Extremities: dorsum of the foot, femoral vein * Other Sites: external/internal jugular vein, subclavian vein.

Question 52

IV Cath Sizes

Answer 52

24g – yellow 22g – blue 20g – pink 18g - green 16g – gray 14g – orange Hagan-Poiseuille Theory

Question 53

IV Contraindications

Answer 53

Anatomy posing risk for extravasation (infiltration) or decreased flow. Extremities with massive edema Burns or injury/surgical laterality Mixed data o extremities post lymphadenectomy Avoid areas with cellulitis, fistula. Some avoid mastectomy side.

Question 54

Serious/Rare Complications

Answer 54

Question 55

What should be done in case of an acute hemolytic reaction?

Answer 55

* Stop transfusion immediately * Notify blood bank. * Recheck blood slip against patient ID.

Question 56

What is the consequence of giving blood with Lactated Ringers?

Answer 56

Citrate in blood can bind calcium in Lactated Ringers, leading to agglutination.

Question 57

What is the significance of 2,3 BPG in hemoglobin function?

Answer 57

It modulates the affinity of hemoglobin for oxygen.

Question 58

True or False: Hemoglobin levels >10 g/dL generally indicate that transfusion is not needed.

Answer 58

True.

Question 59

What is an important consideration for platelet transfusion?

Answer 59

Platelet count <50K in actively bleeding patients.

Question 60

What is the main advantage of using colloids over crystalloids?

Answer 60

Colloids maintain plasma oncotic pressure and stay intravascular longer.

Question 61

What is the risk associated with older PRBC?

Answer 61

Increased potassium concentration as cells lyse.

Question 62

What are the types of veins mentioned for IV access?

Answer 62

* Cephalic * Basilic * Femoral vein * External/Internal Jugular vein * Subclavian vein * Dorsum of the foot

Question 63

What items are needed for IV preparation?

Answer 63

* Gauze (several pieces of 4x4 or 2x2) * Alcohol wipes * Tourniquet * Angio 'vessel' catheter (appropriate size 14-24g) * IV tubing * Tape & bio-adhesive dressing * Rubber gloves * Local anesthetic (lido)

Question 64

What is the first step in the IV insertion process?

Answer 64

Introduce yourself and explain the procedure

Question 65

What is the purpose of applying a tourniquet during IV preparation?

Answer 65

Maximize venous engorgement

Question 66

What should you watch for when inserting the angiocath?

Answer 66

Watch for flash in hub and do not let go of traction

Question 67

What are the sizes of IV catheters and their associated colors?

Answer 67

* 24g – yellow * 22g – blue * 20g – pink * 18g - green * 16g – gray * 14g – orange

Question 68

What are contraindications to starting an IV?

Answer 68

* Anatomy posing risk for extravasation (infiltration) or decreased flow * Extremities with massive edema * Burns or injury/surgical laterality * Areas with cellulitis, fistula, or post lymphadenectomy

Question 69

True or False: IV catheters can be recapped after use.

Answer 69

False

Question 70

Protect Yourself

Answer 70

Potential for contact with patient’s blood is proportional to inexperience. Wear gloves! Patient’s move, blood splatters. Don’t become a Jackson Pollock painting. IV catheters either go into patients of sharps bins. DO NOT RECAP NEEDLES- common cause of needle sticks

Question 71

What are the indications and good sites for arterial lines?

Answer 71

* BP monitoring * Blood sampling * Deliberate hypotension Radial Brachial Femoral Dorsalis Pedis

Question 72

What makes for a good site for arterial line placement?

Answer 72

* Easy access * Relatively superficial vessel * Non-torturous vessel * Collateral circulation distal to the site of cannulation * Migration of thrombogenic material will have minimal impact

Question 73

What is Allen's test used for?

Answer 73

To test for collateral circulation Allen’s test (5 to 10 second refill)- no real clinical indication but old MDs may have you do this. Doppler- no flow = no hokie pokey Pulse Oximeter- if you lose pulse ox waveform, rut roh

Question 74

Pros and Cons of Art-line Sites

Answer 74

Radial Artery – easy to cannulate, accessible during most surgical procedures, adequate collateral circulation (ulnar provides majority of blood flow to hand in 90% of patients). Ulnar Artery – this vessel is deeper and more tortuous than radial. Not a good pick. Both sites are contraindicated in patients with Raynaud’s Syndrome and Buerger’s Disease. (both have profound arterial constriction) Brachial Artery – Large easily identifiable vessel in the antecubital space. Close to elbow = easy to kink catheter or vessel. Collateral vessels may not be adequate in older patient with vascular disease. Femoral Artery – Prone to pseudoaneurysm and atheroma formation as documented following cardiac catheterization. May be only access for burn or trauma victims or for thoracic aortic aneurysm. High rate of ischemia and infection.

Question 75

Other Art Line Sites Precautions

Answer 75

Dorsalis Pedis & Posterior Tibial– Reasonable alternative to radial or ulnar artery cannulation – not present in 5% to 12% of patients. Incidence of thrombolytic occlusion is 8%. Should not be used in patients with diabetes or peripheral vascular disease. If both arms are injured, dorsalis is probably your guy. Axillary – surrounded by the axillary nerve plexus and nerve damage may occur as a result of hematoma formation or traumatic cannulation. Air or thrombus may quickly gain access to the cerebral circulation during flush

Question 76

What are the pros and cons of the radial artery for cannulation?

Answer 76

* Pros: Easy to cannulate, accessible, adequate collateral circulation (Ulnar provides majority of blood flow to hand in 90% of patients) * Cons: Contraindicated in patients with Raynaud’s Syndrome and Buerger’s Disease

Question 77

Risks of Radial Artery Catheterization

Answer 77

Vascular thrombosis Distal embolization Proximal embolization Vascular spasm Skin necrosis over catheter site Line disconnection and bleeding Accidental drug injection Local infection Systemic infection Damage to nearby structures

Question 78

What are the indications for central venous access?

Answer 78

* Monitoring central venous pressure * Fluid administration * Infusion of caustic medications * Total peripheral nutrition (TPN) * Air emboli aspiration * Transvenous pacing * Poor peripheral access Typically done on right side, not left like this picture because of thoracic duct on that side

Question 79

What are relative contraindications to central venous catheter placement?

Answer 79

Coagulopathy/thrombocytopenia Consider avoiding subclavian- difficult to compress venipuncture site May be required for emergency access either way Thrombocytopenia greater risk than coags Platelets >20K no reversal Platelets <20K- give platelets or FFP Site-specific Considerations Avoid indwelling intravascular hardware Pacemaker, hemodialysis catheter Avoid contaminated/potentially contaminated sites- wounds, burns, tracheostomy

Question 80

What complications can occur from central venous catheterization?

Answer 80

Question 81

Catheter Removal

Answer 81

Air can be entrained during insertion, use, and removal Trendelenburg and/or Valsalva can increase venous pressures and minimize negative intrathoracic pressures during inspiration Removal is preferable during expiration when intrathoracic pressure is greater than atmospheric .

Question 82

Stop/Go Anticoagulation

Answer 82

Question 83

What is the Seldinger technique used for?

Answer 83

Central venous catheterization Complications Pneumothorax/hemothorax   Air embolism Arrhythmias Carotid artery puncture/cannulation Chylothorax Infection Chylothorax risk of left side…whut?

Question 84

What are the routes for central venous access?

Answer 84

* Peripheral Arm Veins (PICC) * Femoral vein * External jugular * Internal jugular * Subclavian vein

Question 85

What is the treatment for heparin-induced thrombocytopenia?

Answer 85

LOOK UP AT WHAT REVERSES THIS!!! Life threatening condition that occurs after exposure to heparin Autoantibody activates platelets and can cause thrombosis of veins and arteries Mortality rate up to 20% Two major goals of treatment Halt platelet activation- stop heparin Restart full anticoagulation dose with other agent Selection of alternative agents Argatroban Fondaparinux Apixaban Warfarin

Question 86

What is disseminated intravascular coagulation?

Answer 86

Coagulation and fibrinolysis occurring simultaneously, leading to bleeding and thrombosis

Question 87

What should be avoided when removing a central venous catheter?

Answer 87

Removing during inspiration when intrathoracic pressure is less than atmospheric

Question 88

Aspirin

Answer 88

Irreversibly inhibits cyclooxygenase on platelets American Society of Regional Anesthesia says neuraxial anesthesia is okay on aspirin. Old school rec is to stop 7-10 days before surgery Must weigh risk of embolic event with aspirin cessation

Question 89

Disseminated intravascular coagulation

Answer 89

Coagulation and fibrinolysis simultaneously Procoagulant exposure- Tissue factor a procoagulant Coagulation- thrombi consisting of fibrin and platelets This consumes clotting factors making bleeding worse at surgical site, a “consumptive coagulopathy” End organ damage- from thrombosis and/or bleeding Platelet transfusion, FFP, or Cryo as needed Do not give antifibrinolytics or PCCs (prothrombin complex concentrates) BURNING THROUGH ALL YOUR COAGULATION FACTORS BECAUSE????

Question 90

Approach to Venous Access Catheter Selection in Adults

Answer 90

Question 91

CVC: Central Venous Catheterization

Answer 91

Contraindications: R atrial tumors Fungating tricuspid valve vegetations Contraindications relative to site: Ipsilateral CAE Local sepsis Routes Peripheral Arm Veins (PICC) Femoral vein External jugular Internal jugular*-most common RIJ for us Subclavian vein- surgeons/ICU docs prefer this

Question 92

Central Lines come in All Sorts of Varieties

Answer 92

Is you goal fast fluid administration of multiple med admin? Most common is a triple lumen Learn all the different kinds