Haemostasis Flashcards
Physiologic haemostasis occurs in three interrelated phases: initiation, amplification, and propagation.
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Regarding physiologic haemostasis, initiation refers to platelet aggregation and activation.
F
This is true for amplification.
Regarding physiologic haemostasis, propagation refers to thrombin formation.
F
This is true for initiation.
Regarding physiologic haemostasis, amplification refers to fibrin formation and clot stabilisation.
F
This is true for propagation.
In general, anticoagulation prescribed for secondary thrombotic prophylaxis should not be discontinued for dermatologic surgery procedures.
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Optimizing anaesthesia, and alleviating anxiety and situational hypertension, will significantly reduce the risk of perioperative bleeding.
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Clonidine 0.1mg orally can be used with patient who have anxiety accompanied by situational hypertension and its antihypertensive effects last for 2 -4 hours
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All correct, except lasts for 12 hours
provides antihypertensive, sedative, and anxiolytic effects
Clonidine should be given the day before surgery
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60 mins
Clonidine should be avoided in patients with a preop systolic pressure less tha 100 mmHg
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also avoid if pulse less than 60
Oral midazolam 5-10mg will provide rapid anxiolosis (within 20mins) but can cause significant haemodynamic compromise
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Has no haemodynamic effects
Physical haemostatics include gelatine sponge, oxidised cellulose, microfibrillor collagen haemostat
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They act as a physical mesh onto which coagulation can occur
Aluminum chloride and trichloroacetic acid are most likely to leave pigment particles which may stain the skin
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Least likely, unlike silver nitrate or ferric sulphate
Adjuncts to haemostasis include silver nitrate, ferric sulphate (Monsels solution), aluminium chloride or 35% trichloroacetic acid
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Electrosurgery and suture ligation for haemostasis should be precise to minimize excessive collateral tissue injury.
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Haemostasis is defined as the arrest of bleeding through physiologic or surgical intervention.
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The final haemostatic plug derives 20% of its strength from platelets and 80% from the fibrin network.
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55% from platelets, 45% from fibrin.
Von Willebrand disease is the most common inherited bleeding disorder.
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Affects up to 1% of the population.
Herbs and medication supplements that affect haemostasis include feverfew, fish oil, garlic, ginger, ginkgo, ginseng, dong quai root, bilberry, chondroitin and vitamin E.
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The mild anticoagulation effect of vitamin E may be significantly increased when taken with aspirin and garlic.
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To maximise the vasoconstrictive effects of adrenaline, at least 5 minutes should pass before the first incision.
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15 mins.
Adrenaline should be avoided at acral sites, especially the fingers and toes, due to the risk of ischaemic necrosis or injury
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It is safe to perform ring blocks in patients with peripheral vascular disease, diabetes mellitus or vasospastic/thrombotic conditions
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Tourniquet use without sedation should be limited to 60 minutes or less
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Of the topical haemostatics, aluminium chloride is the least likely to leave pigment particles
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Continuous-wave carbon dioxide laser is a valuable tool for haemostasis, capable of sealing blood vessels of 0.5mm diameter
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Laser haemostasis is best applied to fast capillary bleeding
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Slow – otherwise it’s difficult to get a dry field.
Nd:YAG laser can be used as the sole instrument for haemostasis
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Avoid dt its diffuse and deep destruction.
Bipolar electrocoagulation is safest for pts with implantable debrillators because the current is isolated between the two tips of the bipolar forcepts and there is no distal dispersion of energy.
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Bipolar electrocoagulation causes three times more tissue necrosis than equivalent current through a unipolar electrode.
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Three times less.
Charring and collateral tissue damage is greater with electrocoagulation than with electrodesiccation and electrofulguration.
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Other way around.
A ‘wet’ surgical field (presence of blood) disperses electric current and causes excess charring.
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The ‘dabbing’ method, rather than the ‘roll back’ method, is best for precise electrocoagulation.
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‘roll back’ is best.
Vessels greater than 2mm diameter should generally be ligated.
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A double imbricating suture (consisting of 2 modified external purse string sutures applied peripheral to the area of excision) is a useful technique to control bleeding
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The dorsal nasal artery, inferior and superior labial artery, angular artery and superficial temporal artery are most vulnerable to injury in cutaneous reconstruction.
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New onset of painful swelling within a previously stable and asymptomatic wound is an expanding haematoma until proven otherwise.
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Expanding haematomas do not require intervention.
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Evacuation of a haematoma is not always necessary, especially if it is small, stable and not compromising tissue viability.
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Haematomas evolve through four stages – early development, gelatinous phase, organisation, liquefaction.
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People with Von Willebrands disease may also have abnormalities in Factor VII
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factor VIII
Moderate thrombocytopenia (50 000–100 000) should not affect hemostasis in cutaneous surgery
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even 20-50,000 ok as long a sno signs of bleeding an dnot planning a flap or anything major
If below 20,000 dont operate
the risk of bleeding is considered to be greater with antiaggregants than with anticoagulants
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It is safe to operate if the INR is over 3.0
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usually dont operate in this instance
Sustained systolic hypertension above 180 mmHg is dangerous and may lead to myocardial infarction or stroke as well as bleeding
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Pt fasting prior to surgery helps prevent complications
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more risk of hypoglycaeia and light headedness
fasting often skip their usual meds
ensure they have eaten and drunk if surgery under local only
CO2 laser in continuous waveform setting can be used for haemostasis
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Active drains use positive pressure created by removing air from the collection device manually or mechanically
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negative pressure
all else true
The risk of postoperative bleeding is greatest in the first 24 h, and especially within the first several hours
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cold packs, elevation, rest and compression all help prevent bleeding
After surgery involving extensive skin undermining and mobilization, if patients cannot remain hospitalized, it is good practice to keep them in an observation cubicle for 1–2 h
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so they can be monitored for bleeding and can accentuate the pressure that the dressing may exert, either with patients compressing the treated area with their body – in the case of the trunk – or with the patient’s own hand in the case of facial lesions
In the case of ambulatory patients, it is advisable to assess them 2–4 h after surgery
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to assess for bleeding/haematoma and for pain management
Expanding hematomas require intervention and are medical emergencies in periorbital and cervical locations
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The haemostatic suture is a line of 2-0 sutures placed 1cm out from the surgical margin, mirroring the surgical margin, used for scalp excisions to improve intraoperative + postoperative haemostasis
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JAAD Feb 18
