misc Flashcards
Renal ischemia leads to _____ _______ ______ and the inability to reabsorb solutes and water and excrete waste products.
renal tubular necrosis
At the cardiac level, the continued fall in blood pressure and venous return decreases coronary blood flow. Cardiac muscle ischemia leads to _________ __________ and CO and ultimately to further deterioration of coronary artery blood flow. _________ and _________ accentuate the depression of cardiac muscle function. These changes in combination with decreased venous return worsen _____________ and tissue perfusion.
decreased contractility; Acidosis; ischemia; hypotension
___________ _____ is the result of a volume deficit, either because of blood loss (e.g., resulting from profound hemorrhage), third space sequestration (e.g., occurring with a large colon volvulus), or severe dehydration.
Hypovolemic shock
________ _____ or pump failure occurs when the cardiac muscle cannot pump out adequate stroke volume to maintain perfusion.
Cardiogenic shock
___________ ______ or microcirculatory failure occurs when vasomotor tone is lost. Loss of vascular tone can result in dramatic fall in both blood pressure and _______ _____. Although the drop in blood pressure will initially decrease __________ (which will improve CO), the pooling of blood and loss of venous return results in a severe decrease in _______ and consequently, decreased CO and perfusion.
Distributive shock; venous return; afterload; preload
Approximately _____ of the volume of administered crystalloids will diffuse out of the vascular space into the interstitial and intercellular space.
80%
What would be a reason for pulmonary edema with fluid resuscitation?
anuric renal failure or post-renal obstruction
*other answers possible
_________ ___________ is performed by direct contact between the handheld electrode and the vessel. This causes the vessel wall to shrink, occluding the lumen by thrombosis and coagulum formation.
Obliterative coagulation
In this method of thermal hemostasis, the vessel is initially occluded by a hemostatic forceps. The electrode of the electrosurgical unit then contacts the occluding instrument, which conducts the energy to the vessel, inducing its permanent occlusion.
coaptive coagulation.
T/F: Vessels up to 7 mm in diameter can be coagulated by either obliterative coagulation of coaptive coagulation thermal hemostasis techniques.
False; Vessels up to 2 mm in diameter can be coagulated by either obliterative coagulation of coaptive coagulation thermal hemostasis techniques.
7 mm is the maximum size for vascular staples.
What is the mechanism of action of phenylephrine?
α1-adrenergic receptor agonist causing vasoconstriction and splenic contraction
Mammalian cells are destroyed when cooled to a temperature of _____.
−20° C (−4°F)
T/F: The primary injury from freezing occurs from vascular stasis.
False; The secondary injury from freezing occurs from vascular stasis. As the permeability of vessels is increased, loss of plasma causes local hemoconcentration. Damaged endothelium in arterioles and venules induces thrombus formation of the vessels, and infarction of frozen tissue occurs within hours of freezing.
Primary injury begins with the formation of ice crystals, both intracellular and extracellular. The cell’s outer membrane becomes ruptured by intracellular crystals, and ice formation outside the cell dehydrates the cellular environment, resulting in lethal electrolyte concentrations and pH changes. When organelles are damaged, the cell loses its ability to regulate ion permeability and cell death ensues.
What is the boiling point of liquid nitrogen?
−195.8° C (−320.4° F).
T/F: Cryosurgery is useful for treatment of fractured splint bones.
False; Freezing cortical bone causes cell destruction and reduces the strength of the bone by 70%.
What are the three broad category objectives of laser surgery?
incision/excision, ablation, and coagulation
Laser ____________ and _________ result in cell disruption and “vaporization” of tissue into smoke.
incision/excision and ablation;
excision is simply incising to dissect and remove tissue, and ablation refers to vaporization of tissue into smoke.
Laser ___________ refers to denaturing of tissue proteins, which grossly appears as blanching and contraction of tissue.
coagulation
________ concentrated laser energy (i.e., )_______ power density) is required to efficiently cut tissue with minimal heating of surrounding tissue.
Highly; high
This laser emits energy at 10,600 nm in the far infrared range; water absorbs this wavelength so completely that energy penetrates only 0.03 mm into tissue.
CO2 laser; the ability to precisely control the effect makes the CO2 laser safe for application to tissue overlying critical anatomic structures.
Using CO2 laser, hemorrhage from vessels ____ or less in diameter and lymphatic drainage are largely eliminated/
0.5 mm; Better hemostasis in continuous mode if wound is to be left open. Pulsed-mode has less collateral tissue heating, so is better for primary closure.
In their purely optical forms, these lasers are absorbed by dark pigment (such as melanin and hemoglobin) and poorly absorbed by water.
the 1064-nm Nd:YAG and 980-nm GAL diode lasers, which wavelengths behave almost identically in tissue.
When the tissue is not obviously dark, the laser energy will convert to heat more slowly as it encounters sufficient pigment or protein deep to the surface, which may take several seconds. that distance could be a few millimeters in pale skin or mucous membrane or a few centimeters in an eye if only cornea and clear aqueous or vitreous humor is encountered. as tissue blackens, more laser energy is absorbed until black char accumulates and limits penetration. to continue, the char must be physically removed or time for tissue to slough must be allowed.
Vascular stasis occurs when melanin-rich tissues absorb the laser energy and conduct heat to the vascular endothelium, where the coagulation cascade is activated. in tissues with low melanin concentrations, hemostasis occurs when hemoglobin absorbs the laser energy and conducts thermal energy to plasma protein.
T/F: the 980-nm diode laser is absorbed by water three times more than the Nd:YAG laser and lower-wavelength diode lasers.
True; the practical effect is a much more efficient contact incision in tissue in the upper airway with the 980-nm diode laser
________ and _____ lasers are the instruments of choice for equine endoscopic surgery because the energy is delivered through flexible _______ fibers, which can be inserted through the biopsy channels of video endoscopes.
Diode and Nd:YAG; quartz
T/F: When using a quartz fiber, blackening the tip of a bare fiber by firing it on a tongue depressor or with a black permanent marker causes the energy to be absorbed at the fiber tip so it cuts efficiently.
True
The ___________ laser is a pulsed laser that has been used in orthopedics, but more recently it has been applied in urology. The wavelength is substantially absorbed by water, an advantage for endoscopic ablation of soft tissue while protecting deeper structures. This laser will ablate or “drill” cortical bone.
near-infrared (2100 nm) Ho:YAG
the wavelength is substantially absorbed by water, an advantage for endoscopic ablation of soft tissue while protecting deeper structures. The effect is enhanced in a water medium, which concentrates the energy within an air bubble formed where the laser contacts tissue. in an air medium, the delivery is noisy, and tissue is displaced slightly with each pulse. in the upper airway, the noise can be distracting for horses, and the delivery is not as precise as with the continuous Nd:YAG or diode lasers.
The laser-generating medium is an organic dye that is activated by a flash lamp or another laser, resulting in a visible 400 to 700 nm wavelength absorbed by hemoglobin and urinary calculi.
Pulsed dye laser
T/F: Clear glass with protection from all angles is adequate for the Ho:YAG
laser.
False; Clear glass with protection from all angles is adequate for the CO2 laser, but optical density recommendations are specific for the near-infrared and other wavelengths and should be followed for the wavelength of the laser.
The far-infrared Ho:YAG and CO2 lasers are _______ absorbed by water; therefore, they penetrate _______ into skin.
highly; minimally
The near-infrared Nd:YAG or GAA Diode lasers are absorbed more by _____________ of the _______ layers.
the darker pigments; deeper
What are the layers of the epidermis from superficial to deep?
stratum corneum
stratum granulosum
stratum spinosum
stratum basale
Concerning the layers of the epidermis, which layer slows water loss and functions as a barrier to harmful substances?
stratum corneum
T/F: Other cells found in the epidermis include melanocytes for production of melanin, Langerhans’ cells for mechanoreception of light touch, and Merkel cells to help fight infection by engulfing foreign material.
False; Other cells found in the epidermis include melanocytes for production of melanin, Merkel cells for mechanoreception of light touch, and Langerhans’ cells to help fight infection by engulfing foreign material.
What are the two layers of the dermis?
the superficial papillary layer and the deep reticular layer, and it provides support for the epidermis. The dermis in the lumbar, sacral, and gluteal regions has a third layer of collagenous fibers.
T/F: The presence of foreign material reduces the number of bacteria necessary for infection by a factor of 10 (i.e., from 10^5 to 10^4 bacteria per gram of tissue).
True (A&S pg 307)
