Biomedical Engineering Reference
In-Depth Information
Thermoregulation
Both hypo- and hyperthermia are undesirable, as the former
causes progressive depression of organ function and the
latter causes cell damage. The authors recommend main-
taining an intraoperative rectal temperature of 98.6
anesthetic depth and dorsal recumbent positioning may
contribute to the tracheal/bronchial collapse and secondary
apnea.
Surgical Manipulation and Handling of Tissues
and Organs
Knowledge of anatomy, vascular supply, innervation, and
organ function is paramount and gentle tissue handling is
a must!
99.8 F,
e
101 F just before
recovery. Heating pads, water bottles, and Safe-n-Warms,
when used, should be placed close to the subject's skin but
not touching it and covered with towels to form a heat tent.
Even if an electrically heated surgical table is in use, it needs
to be covered with towels or blankets to separate the animal
from a metal surface. Passively wrapping extremities of
smaller nonhuman primates with bubblewrap “mittens” and
“booties” is quite effective in maintaining body tempera-
ture. Warm air circulating devices (e.g. Bair Hugger
( Figure 14.2 ) or products from other manufacturers on the
human or veterinary market such as the Hot Dog or the
Cincinnati Sub-Zero Blanketrol Hyper-Hypothermia
System) may be more effective than old-fashioned water
circulating blankets. Warmed intravenous fluids, which
should not be warmed beyond 107.6 F, have some value,
although effective use is limited by the volume and heat
content. Induced, controlled, and transient hypothermia
(94
which can be slightly increased to 100
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Integument
Epidermis is the outer layer which rests on the dermis
composed of two layers, pars papillaris and pars reticularis
( Montagna, 1972 ). Before making an incision, the
“measure twice, cut once” approach and stretching the skin
for a smooth cut are advised. Skin removal is discouraged
unless it is absolutely critical and controlled wrinkling to
store extra skin for future repairs should be employed
instead. For closure, the authors recommend nonabsorb-
able, monofilament, nonwicking, synthetic materials (see
further for details) while capillary or reactive ones should
be avoided. Subcuticular closure, strongly recommended
for many routine closures in nonhuman primates, will
minimize picking and should use synthetic, absorbable
material. All stitches should be tied using square knots and
short-trimmed to make them more difficult to be picked.
Some researchers believe that using stainless steel suture
and leaving ends of 4
96 F) can be used to prevent or counteract potentially
dangerous body temperature increases (e.g. cranial appli-
cation of exothermic methacrylate, extensive drilling during
craniotomy, screw applications, or methacrylate removal).
e
5 mm that serve as “barb-wires”
prevents picking. The authors do not share this belief and
recommend using this type of suture only when needed for
extra strength. A determined nonhuman primate will pick
on sutures regardless of what material is used. During
closure, equal bites taken on each side of the incision and
starting in the middle to progress towards each end in
longer incisions (
e
Blood Gases and Ventilator Use
Arterial access is required for blood sampling. Respiratory
acidosis may result from insufficient O 2 and CO 2 exchange
under spontaneous respiration in long procedures. It can be
corrected with a ventilator, although its indiscriminate use
can lead to respiratory alkalosis (for more details see
Chapter 17). The authors recommend use of positive
pressure mechanical ventilation for surgical procedures of
longer
10 cm) will keep closures straight and
minimize undesired wrinkles and “dog ears.” When closing
infected wounds, drains need to be placed. Passive drains
>
than 30 minutes, particularly where a greater
(A)
(B)
FIGURE 14.2 Supplemental heat.
(A,B) Air circulating device.
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