Miscellaneous Flashcards
William Halstead’s principles
1- Gentle handling of tissue
2 - Meticulous haemostasis
3 - Preservation of blood supply
4 - Strict aseptic technique
5 - Minimum tension on tissues
6 - Accurate tissue apposition
7 - Obliteration of deadspace
Consequences of protein-calorie malnutrition (PCM)
Organ/muscle atrophy
Delayed wound healing
Impaired immune response
Anemia
Hypoproteinemia
Death
Diagnosis of Protein-calorie Malnutrition (PCM)
- Weight loss of more than 10% normal body weight
•Anorexia or hyporexia (i.e., suboptimal intake of nutrients) for >5 days or an expected decrease in nutrient intake of >5 days
•Increased nutrient loss (e.g., through vomiting, diarrhea, severe wounds, or burns)
•Increased nutrient needs (e.g., due to trauma, surgery, infection, burns, or fever)
•History of chronic illness
•Serum albumin concentration ≤2.5 g/dL
Myelogram -  contraindications and possible complications
Contraindicated in patients with:
•Suspected inflammatory central nervous system disease
•Elevated intracranial pressure
•Historical or clinical indication of an underlying encephalopathy
•Potential complications
•Seizures
•Parenchymal damage from insertion of the needle
•Transient neurologic worsening
•Permanent neurologic worsening due to inadvertent contrast injection into the parenchyma or the central canal of the spinal cord
The two major mechanisms of suture absorption are
Enzymatic and hydrolytic
Why is catgut coated with chromium?
Chromium increases collagen cross linkage, decreasing absorption rate and tissue inflammation
The only reasonable uses for catgut
Rapidly healing tissues such as mucosa or ligation small vessels.
Characteristics of chronic catgut:
Absorption mechanism
Time until complete absorption
Absorption mechanism: enzymatic
Time until complete absorption: 2-3 weeks
Polyglycolic acid: Dexon
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 2-3 months
Time until 50% loss of tensile strength: 2-3 weeks
Polyglactin 910: Vicryl
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 2-3 months
Time until 50% loss of tensile strength: 2-3 weeks
Poliglecaprone 25: Monocryl
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 3-4 months
Time until 50% loss of tensile strength: 1 week
Polydioxanone: PDS II
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 6 months
Time until 50% loss of tensile strength: 5-6 weeks
Polyglyconate: Maxon
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 6 months
Time until 50% loss of tensile strength: 4-5 weeks
Glycomer 631: Biosyn
Mechanism of absorption:
Time until complete absorption:
Time until 50% loss of tensile strength:
Mechanism of absorption: hydrolysis
Time until complete absorption: 3-4 months
Time until 50% loss of tensile strength: 2-3 weeks
Potential use for silk suture material; Where should it be avoided
Useful for ligation of large vessels because it insights significant addition reaction. Should not be used in infected sites or anywhere tissue reaction may be considered detrimental
Strongest of commonly used synthetic suture materials. Commonly used for tendon and ligament repair
Polypropylene
Properties of nylon suture - expected loss of tensile strength in acid environment, timeframe
50% loss of tensile strength in 12 weeks
Ultra high molecular weight polyethylene suture With significantly greater strength in three-point banding when compared with 18 gauge steel
FiberWire (strongest of all polyblend sutures)
Two types of surgical meshes - which one is stronger
Woven and knitted - woven meshes are stronger because filaments are packed tightly
What is the importance of pore size in the concept of surgical meshes?
The presence of too small pores prevents ingrowth of capillaries and fibroblasts, causing encapsulation rather than incorporation
Typical site of failure after application of surgical meshes
Mesh/tissue interface
Most common complications associated with the use of surgical meshes
Visceral adhesions, mesh migration/extrusion, fistula formation, infection
Do use of linear stapling devices has been associated with a significant decrease in the formation of granulomas if used in this organ
Lungs
Four motions of the scalpel’s cutting edge
Sliding, pressing, sawing and scraping
3 forces used when cutting with scissors
Closing, shearing and torque
Adequate ring instrument grip
Tripod grip
Interrupted suture patterns utilized in small animals
Simple interrupted
Modified Gambee
Three mattress patterns: horizontal, vertical, cruciate
The difference between Cushing and Connell suture pattern
Both continuous and inverting patterns, however Cushing only includes the dermis (partial thickness) while Connell includes dermis and sub dermis (full thickness )
Appropriate cut end length for synthetic suture
3 mm
Two types of ligatures
Circumferential and Transfixation
Three main techniques that can be used to augment hemostasis
Reduction of blood flow to the affected area
Topical hemostatic agents
Anti-fibrinolytic‘s
Approximate time until platelet aggregation
Approximate extra time until clot cross-linked with fibrin matrix
30 seconds
2 to 3 minutes
Abdominal counterpressure (bandaging) to control hemorrhage -
Evidence? Effectiveness? Precautions and contraindications
Shown to improve survival in experimentally-induced hemoperitoneum in dogs but not clinically proven. Human evidence suggests that it might raise intrathoracic and intracranial pressure, so contraindicated in these cases. Must monitor urine output due to possible intraperitoneal hypertension
Topical vasoconstrictors
Epinephrine, adrenaline, ephedrine
Adrenaline dilution for intranasal Epistaxes control
1mg/ml
Pringle maneuver
Temporary occlusion of the hepatic artery and portal vein to control hepatic hemorrhage
Vessels that can be occluded on a temporary basis to control hemorrhage/assist with surgery
Hepatic artery, carotid artery, renal artery, aorta, femoral artery, caudal vena cava and tumor artery supply
Vessels that can be permanently occluded without significant consequences
1) Both common carotid arteries, if vertebral artery is preserved and circle of Willis is functional (not in cats)
2)Both jugular veins (not in cats)
3)Brachiocephalic veins
4)Brachial arteries
5)Hepatic veins
6)Femoral arteries
7)Both external iliac arteries
8)Both common iliac veins
9)Both femoral veins
10)left renal vein
11) “Abdominal vena cava caudal to liver, in the case of chronic compression and established collateral circulation or concurrent right nephrectomy”
Circle of Willis - importance; difference between dogs and cats
The Circle of Willis is the joining area of several arteries at the bottom (inferior) side of the brain. At the Circle of Willis, the internal carotid arteries branch into smaller arteries that supply oxygenated blood to over 80% of the cerebrum.
Cats do not possess a complete anastomotic circle, and thus ligation of the external carotid arteries will lead to cerebral ischemia (fatal).
Potential complications associated with the use of tourniquets
Hypertension/hypercoagulopathy during use; hypotension, increased fibrinolytic activity (increased bleeding), Reperfusion injury (edema, ischemic tissue damage, nerve damage.
Current recommendations for the use of tourniquets intra-op
Pneumatic tourniquets are favored over Esmarch; keep pressure around 100 mmHg above systolic pressure or monitor distally using a Doppler to determine the least amount of pressure necessary to stop arterial flow. Maximum times vary from 15 to 30 minutes depending on site
Situations in which the exsanguination of the limb is contraindicated prior to the application of a tourniquet
Infection or neoplasia
What precaution should be taken if a bandage is applied to a limb immediately after a surgical procedure that employed the use of a tourniquet?
The bandage must be replaced within 24 hours. Reperfusion injury increases the chance of swelling/postoperative edema which may cause the bandage to become excessively tight and lead to tissue necrosis
Three groups of hemostatic agents
“• Mechanical hemostatic agents
• Active hemostatic agents
• Hemostatic sealants”
Situations in which hemostatic products are contraindicated
When blood salvage techniques (autotransfusion) are in use because particles can pass through the 40 µm filters.
Also contraindicated in intravascular spaces doe to the risk of thromboembolism