Systems for Recovery From Anesthesia
By Douglas J. Herthel, DVM
A variety of systems are in current use to assist the recovery
of an equine patient from general anesthesia. The safety of the
anesthetized horse and of the personnel involved is the prime concern
when a recovery protocol is selected. Smooth, controlled recoveries
are especially desirable following orthopedic procedures. Since
protection of the surgical repair is essential. A successful recovery
is also more difficult after orthopedic procedures because of the
pain associated with bone repair. Especially in cases of upper long-bone
fractures in which analgesia cannot be obtained by perineural anesthesia.
The recovery protocols described herein are used at the Alamo Pintado
Equine Medical Center. Two types of recovery systems are commonly
used; a recovery room with ropes for assisted recovery, and a warm
water pool recovery. The two systems allow for flexibility and backup
for the difficult recovery case.
Many factors are involved in selecting the type of recovery system.
The fracture type and extent, the temperament of the horse, and
location & size of the cast required, and the type & duration
of anesthesia all must be analyzed. Throughout a procedure, any
of these factors can change and affect the type of recovery system
implemented. Additionally, a horse having difficulty in a recovery
room can be immobilized and transferred to a heated recovery pool
via a sling or in soft hobbles. The same move can be made in reverse,
although need for this is very unlikely.
The anesthetic regiment used at this clinic includes a combination
of some or most of the following: xylazine hydrochloridea, detomidine
hydrochlorideb, butorphanol tartratec, diazepamd, ketaminee, isofluranef,
halothaneg, and atracuriumh. Combinations of these drugs have worked
well for the anesthesia and recovery of orthopedic patients.
Recovery Room
The recovery room should be in close proximity to, but separate
from the surgery suite. The recovery room can be the same room as
the induction room if the surgical caseload is light. The recovery
room should have padded walls and an easily cleaned, nonskid floor.
A 12 inch-thick, moveable, vinyl-covered mat (5ft by 10ft) is placed
under the animal during recovery. The best position for recovery
is injured leg up, with the legs halfway off the mat and toward
the wall. The recovery room should also have recessed wall rings
for ropes. Head and tail ropes allow two people to assist a horse
in rising. They allow the attendants to control the movement of
the horse and to aid in supporting the horse while allowing it to
lean against the wall for balance. The two attendants can maintain
a safe distance from the recovering horse at the same time to prevent
the horse from struggling and injuring itself. An escape route behind
the two assistants is mandatory. This is system keeps the horse
from using no more than a third of the recovery room and prevents
the recovering horse from blocking the escape route for the attendants.
Sometimes it is helpful to lean against the chest of the horse immediately
after it regains it’s feet, to stabilize the horse by providing
contact with the padded wall on the opposite side.
The 12-inch-thick, vinyl-covered foam mattress allows the recumbent
patient to remain comfortable while exhaling the residual gaseous
anesthetics. Postanesthetic sedation with xylazine, butorphanol,
or detomidine allows the horse to exhale anesthetic gases before
attempting to stand. This extends the recumbency time in recovery
but prevents premature efforts to stand and increases the likelihood
of a safe and smooth recovery from anesthesia. The presence of the
anesthetist and an assistant in the recovery in the recovery room,
monitoring the patient and assisting recovery with the use of head
and tail ropes, is essential to prevent accidents. All room recoveries
should be rope-assisted.
The recovery room should be quiet and darkened to reduce environmental
stimulation to the horse. The room should be equipped with a suction
line, an oxygen insufflation tube, an oxygen demand valve, and a
case of emergency drugs and syringes. Close monitoring during the
recovery phase is as imperative as intraoperative monitoring and
includes vital signs, mucous membrane color, blood gases, chest
excursion, eye signs, and pulse oximetry.
Floor surface is a critical factor in safe recoveries. The surface
should be nonslip, even when wet. A slightly cushioned surface with
a nonslip covering is ideal, for example, a removable floor pad
consisting of a ½ inch thick, high-impact rubber material
covered with an outdoor commercial carpet. A moveable pad (10 ft
by 4 ft) works well, allowing thorough cleaning of the recovery
room floor and mat. This system for room recovery is safe and atraumatic
to patients and can be modified when necessary. The padded recovery
room offers minimal risk of further injury to horses recovering
from anesthesia following repair of small-bone fractures or application
of a cast to lower limb fractures, and horses having undergone arthroscopic
procedures.
Pool Recovery
The additional option of pool recovery is invaluable and often
lifesaving in cases of difficult recoveries from prolonged and complicated
procedures. Immersion of the horse in water after long-bone fracture
surgery is usually the best way of protecting the integrity of the
repair during recovery from anesthesia. It is also reassuring to
have the pool recovery option in instances of certain anesthetic
complications or other circumstances.
The pool should be designed to easily clean, safe to work around,
economical to operate, and effective in helping horses with fractures
to recover from anesthesia. It should also be designed to accommodate
the loading and unloading of horses that have problems resulting
in prolonged periods of recumbency. An additional function is the
rehabilitation of horses with orthopedic conditions or laminitis
by allowing these horses to swim.
Ideally, the pool should be built from poured concrete, plaster,
and tile and should be filtered and heated with conventional pool
equipment. Satisfactory dimensions are 12-ft long, 4-ft wide, and
8 ft deep. A hydraulically driven scissor-lift elevates and lowers
the floor from 7 ½ ft deep to ground level. The hydraulic
pump also operates a Jet Ski propeller recessed in the front of
the tank. This serves to propel up to 1500 gallons of water per
minute against a horse that is swimming for exercise and physical
therapy. The pool also has strong Jacuzzi jets that are used for
physical therapy.
The pool level can be quickly adjusted by adding water or pumping
water out. The temperature can be adjusted from cool to very warm
but usually remains at 90? to 95? F (32.2? to 35? C). On occasion,
all the water is drained from the poor, leaving the recovered horse
standing in the empty pool. Straw bedding can be placed on the lift
floor to covert the pool to a narrow tie stall. Usually the sling
used to transport the anesthetized horse to the pool is left on
the horse while it remains in the empty pool. The metal grate floor
allows water to flow through it without surging, as the floor is
quickly elevated and lowered during the various stages of the horse’s
recovery. The pool decking is covered with nonskid rubber matting
to allow traction for the horse when it leaves the pool. The pool
should be built directly beneath a rail system that carries a crane
lift and trolley, which services the induction room, surgery suite,
and recovery room. This location allows transport of the anesthetized
horses from surgery or recovery to the pool, either in a sling or
upside down in soft hobbles.
Pool Recovery Procedures
Special intraoperative and postoperative procedures are necessary
if a surgical patient is to undergo recovery in a pool. The most
important is waterproofing the surgical wounds. Additionally, bandages
or casts must be water-resistant and durable in water.
Wound closure requires extra effort to provide a multi-layered,
tight closure. An inverted, subcuticular, transdermal, continuous
suture pattern is used in place of interrupted skin sutures, and
wound drains are avoided. The wound is then sprayed with a cyanoacrylate
wound cementi. This spray and a tight closure effectively waterproof
wounds for as long as 4 days under water. If bandaging is required,
only a non-adhesive dressing and gauze roll are used, with Elastikon
placed over the bandaging. These wraps are changed shortly after
the horse exits the pool. If casting is required, a water-repellent
cast paddingj is used. This padding is applied easily and allows
the skin to dry quickly after the horse leaves the pool. Horses
with Gore-Tex cast padding, a fiberglass cast have been placed in
the pool to swim every second day for 30 days and have surgical
wounds, and skin that are still in excellent condition at cast removal.
At the completion of surgery, the horse is disconnected from the
anesthetic machine and elevated from the surgery table with a sling
and hoist. The arterial catheter and jugular catheter are anchored
and glued in place. The endotracheal tube is also anchored so that
intermittent positive pressure ventilation can continue with use
of a Hudson demand valve. The horse is monitored and ventilated
as it is transported to the recovery pool. Prior to lowering the
horse into the pool, the floor is depressed to 7-½ ft, and
two inflated car inner tubes are placed around the animal’s
neck. A long rope is tied to the tail and run to a pulley on the
monorail. Two ropes are tied to the halter, and the horse is lowered
into the pool the remainder of the distance. The end of the endotracheal
tube must be kept out of the water. The horse remains on the oxygen
demand valve, an arterial line is available for monitoring blood
gases, and drugs & fluids can be administered through the intravenous
catheter. The sling remains in place but does not support weight;
the horse is essentially floating. As the horse starts to recover,
it is generally quiet in this environment. Some sedation is useful;
especially prior to removal of the sling and before the floor is
fully elevated to ground level. When the horse is adequately stable
in the water, the floor is elevated to ground level and the horse
is allowed to walk off the pool floor. In some cases of major long-bone
fractures, the sling is left on for safety and support. The use
of sedation, warm water, the tail rope, two head ropes, the sling,
and the adjustable floor gives the equine anesthetist a safe method
of assisting in the recovery of seriously injured horses.
The temperature-controlled pool with its Jacuzzi jets is an ideal
environment for therapeutic treatment of postsurgical or idiopathic
myositis, neuropathy, and weak patients recovering from surgery,
and for water exercise therapy for orthopedic patients. The warm
water and Jacuzzi jets massage and relax painful muscle conditions.
The exercise provided by the patient’s swimming against the
jets is nonconcussive and more therapeutic for orthopedic cases
than rehabilitation using water treadmills. Such swimming allows
for muscular rehabilitation with minimal skeletal stress. The same
therapy can be used for horses with severe laminitis that have difficulty
in walking but would benefit from the warm water, massage, and mild
exercise.
Horses that are weak and remain recumbent can be kept in the pool
for hours, days, or even up to a week to prevent cachexia and pressure
sores and to expedite recovery. Patients quickly become accustomed
to the routine and require a minimal number of staff members to
complete the therapy. In most cases, the patients enjoy the pain-free
time they spend in the pool.
-return to article list-
|
