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                          WHEN LIFE HANGS IN THE BALANCE.
                 "Applying basic science to the rescue of animals in crisis"
                A lecture in honor of John Greve, DVM, PhD, Professor.

          Dennis T. (Tim) Crowe, Jr., DVM, DACVS, DACVECC, NREMT-2, NCFF
        President, Veterinary Surgery, Emergency, and Critical Care Consulting, Bogart, Georgia
                  Surgeon, All Pets Emergency and Referral Center, Alpharetta, Georgia


Just a little story about one of the times I remember how I came to admire Dr. Greve: I can still recall
how I was really struggling with trying to remember all that was given to us to remember in his class. So
one day I asked him if he had any words of wisdom he could give me. We walked over to his office and I
remember looking in a bottle he had there with a very large worm inside. I was curious so he showed it to
me and said it was a large "kidney worm or Dioctophyma renale…..the largest nematode known to man."
Dr. Greve said this while having an exciting mystifying smile on his face. That worm really impressed
me. But also was impressive was the way Dr. Greve said Dioctophyma renale, in almost a reverent and
awe inspiring tone. I never forgot that. Later I actually removed one from a dog’s abdomen when I was a
surgeon at the University of Georgia and as I did it I could feel my face light up with a similar grin that
Dr. Greve on the day he had shown me that large worm. I told the students around me watching the
exploratory surgery about Dr. Greve and said this is a cool finding". "See here this is the largest nematode
known to man and it's official name is Dioctophyma renale" Wow! I had just blurted out the name
without even having to think about it!. And as I was thinking of that I was also thinking "Dr. Greve would
be proud of me having had remembered the name of that parasite after more than 20 years past on that
memorable day... when Dr Greve helped me to see how important parasitology is. I must admit to Dr.
Greve that I did have to review the life-cycle in the Merck Manual when I got out of the operating room.
Sorry. .....e noté emprota consulto parsitos

INTRODUCTION - The purpose of this address is to provide information that will help the practicing
veterinarian and veterinary students concerning care of the critical patient. This will include an overview
of some of the general concepts; basic physiology and anatomy involving oxygen delivery;
recommendations concerning readiness for the patient care; and care and assessment guidelines for care
of the critical patient. Throughout the address patients will be presented that will exemplify the critical
care they needed to emphasize key points. The references will provide further information on each
specific area if the reader chooses. The first 8 are particularly informative with photographs and case

examples (1-8).

GENERAL CONCEPTS - Because of the life-and-death conditions involved with critical patients each
decision made and the care subsequently provided is consequential (1). Even what is told to an owner
with their initial phone call inquiring about a potential visit and what they should do at home before
coming can make critical difference in what occurs. An example is a dog "Annie" with small amount of
fluid dripping from her spay incision and a small swelling noted there. The technician answering the
phone suggests Anne be seen and makes an appointment for that afternoon. Another similar scenario is
called in. This dog "Alice" also has fluid dripping from a spay incision. Another technician taking the
call suggested that the owner wrap a towel around Alice's body and transport her carefully right away and
warned the owner not to let the dog jump out of the car. On arrival at the hospital Annie was allowed to
jump out of the car and dumped her intestines on the surface of the parking lot. She attempted to run and
dragged the intestines into dirt and gravel and tore it open. She was admitted for immediate surgery. Alice
on the other hand presented with a large towel around her "middle" and was carefully moved into the
triage area. On removing the towel omentum was found hanging out. Saline was added to the drying out
omentum and the dog was also admitted for surgery.

Another example is a patient "Copper", an Irish Setter who was choking from a airway foreign body and
the owner called in a panic. The veterinarian instructed the caller on how to remove the ball from
Copper's throat. The dog passed out and with a sweeping motion the ball was removed by the owner. The
owner did a minute of rescue breathing before Copper started breathing OK on his own. The owner
brought Copper in to get checked out. Other than for a little unsteady gait Copper was found to be OK.
He made a complete recovery.

Although many critical patients will require much time and expense to provide the care necessary to
resolve their medical or surgical problems, others will not, particularly if the care needed if done early in
the course of the illness or post-injury as exemplified by two of the three patients described above.
Although both Annie and Alice recovered completely the cost for Annie was greater than 3 times that
needed for Alice as she required a bowel resection and extensive irrigation to clean off mesentery and had
to stay in the hospital on intravenous fluids and antibiotics for several days. Alice required only a nigh in
the hospital and the problem was not nearly as potentially life-threatening. The owner of Annie was also
not at all happy when she found out the difference in the care that was required between the two dogs as
the two owners "compared notes" while visiting in the lobby. She said the hospital "may hear" about that
further from her attorney as her dog Annie had to undergo much more than Alice; all because she was not
told about the risks involved on the phone as Alice's owner was before transport. Hence the need for
appropriate and timely care, even from the time of the initial call. This has been published and
recognized as one of the keys to successful emergency care in veterinary medicine (1-3).

Critical care and emergency care also involves ongoing assessment and monitoring, and the execution of
corrective and supportive procedures and activities that also been previously published (2). These are
very briefly noted as follows:
1. Airway and ventilatory assessment, and support; oxygen supplementation (3,4,8).
2. Cardiovascular assessment involving blood flow and oxygen delivery and support (2,6).
3. Neurologic assessment and necessary care as needed including analgesia, anesthesia, anxiolysis (3).
4. Gastrointestinal system support including early enteral nutrition. (1,2,7).
5. Fluid and electrolyte assessment and support (1,2,7).
6. Specific organ function assessment and support (liver, pancreas, kidney) (1,2,7).
7. Musculoskeletal and dermal assessment and support (1,2,7).
8. Emotional support for the patient, owner, owners family (1,2).
9. Emotional support that also extends to those providing the care (1).

OXYGEN DELIVERY -. Multiple factors affect oxygen delivery to the cells (4,6,9). These include:
1. Amount of oxygen provided to the patient to breathe (FiO2).
2. Effectiveness of oxygen delivery to the alveoli (PAO2).
3. Effectiveness of oxygen exchange at the capillary (PaO2).
4. The presence of sufficient hemoglobin to carry the oxygen and release it at the tissue level (Hb).
5. Global cardiac output and adequate flow to the tissues (CO); Cardiac output is determined by
circulating blood volume, cardiac muscle strength, vascular tone and heart rate (9). The best way to
assess tissue blood flow and effective cardiac output getting to the peripheral tissues, from a practical
point of view, is to listen to Doppler blood flow on a beat to beat basis (1,2,10-12). The Parks Medical
Electronics, Inc., Ultrasonic Doppler Blood Flow Detector Model 811-B (19460 S.W. Shaw, Aloha, OR
97007 1-800-547-6427) and the accompanying pediatric flat probe are approximately $750.00 and are
very good for the monitoring of flows in both dogs and cats. Blood pressure can also be monitored by
use of an appropriately sized blood pressure cuff (40% the circumference of the limb) placed proximal to
the placement of the flow probe. As has been documented capillary blood flow is dependent on blood
pressure differential between the arterial and venous beds (9). But blood flow in itself, as continuously
monitored by auditory assessment of flow sounds, in my opinion, is the most important to monitor and
can easily be done by listening to flow characteristics with the probe placed over the palmar or plantar
arterial arch. A "full sound" even in the face of a lower than normal systolic pressure indicates "adequate
arterial blood flow" whereas a "short weak sound" heard even in the face of a high or normal systolic
pressure indicates inadequate arterial blood flow. This can be explained by increased vascular resistance
caused by arteriolar vasoconstriction leading to decreased flow (9). The Doppler unit can also be taped to
an esophageal stethoscope and used to monitor aortic blood flows in low flow and unconscious states
with significant accuracy (10). It can also be used to effectively monitor blood flow cranially during

CPCR using the probe on the eye (11,12).

Success in emergency and critical patient care means patient care survival with as minimal long term
morbidity as possible. This requires "High Priority Resuscitation" or resuscitation procedures that can not
wait and they MUST be addressed immediately upon arrival and continued to be addressed throughout
the course of care. They are those procedures aimed at maximizing oxygen delivery and are based on
both basic anatomy and physiology. The treatment must be appropriate and must be provided in a timely
manner (1,2). Research has shown that if cellular hypoxia to the gastrointestinal tract in dogs continues
beyond an hour even though global resuscitation from blood loss appears adequate death from organ
dysfunction and sepsis from gastrointestinal bacterial translocation and endotoxin absorption across the
gut wall will likely occur a day to several days following the insult (13,14). The patient might recover
initially but will then suffer or die later from gastrointestinal, renal, hepatic, pancreatic malfunction due to
apoptosis (13,14). Therefore successful critical care again reiterated requires timely and accurate patient
assessment and resuscitation in proper sequence according to physiologic priorities (airway, beathing,
circulation, disability, and everything else) and then continued assessment and supportive care as required
(supplemental oxygen, respiratory support, nutritional support, fluid and electrolyte support; physical
therapy; and skin and catheter care, etc.) (1-8). The first two of these components occur simultaneously
in the seriously injured or ill patient and are included in the decision making that must performed
accurately and in as short of times as possible. One thing that can not be bought is TIME. Therefore the
decisions made not only have to be accurate but also the resuscitation care must be completed with
expedience. Hence the emergency and critical care team must always be in a state of readiness (1,2).

READINESS - The goal of initial and subsequent care of the critical patient is to determine the critical
life-and-death disorders present; resuscitate, and do what ever that require to improve the delivery of
oxygen (O2) and nutrients to the tissues; to arrest the cause of the problem or problems identified (i.e.,
opening the airway, controlling hemorrhage, etc.); correcting anatomical defects or malfunctions caused
by the injury or disease before their consequences impart further serious life-threatening complications;
and provide continued supportive care required to allow the reestablishment of homeostasis. To provide
this in a timely and most efficient fashion takes effort on the parts of the whole veterinary medical team.
A state of readiness must be maintained. This involves having the appropriate equipment, supplies and
drugs available and assembled in a organized fashion (1,2). From training in both veterinary and human
critical care and rotations at several university and private veterinary and human centers including the
Shock-Trauma Center in Baltimore, the following recommendations are made regarding the delivery of
critical care:
1. Have at least two trained support staff and one veterinarian on duty at all times (24-7-365).
2. Have a "Ready" triage-resuscitation area set up at all times using the "open concept".
3. Have an area in the hospital that is designated for the care of critical patients (Critical Care Unit).

4. Have a "24-hour lab" with the ability to do arterial and venous blood gases and electrolytes.
5. Have "24 hour" imaging capabilities that allow radiographic and ultrasound assessment.
6. Have an operating room in readiness to allow emergency rapid deep cavity interventions, etc.
7. Have pharmacy capabilities that includes most resuscitation and support drugs and blood products.
8. Use check-off and flow resuscitation and critical care flow sheets for recording and monitoring.
9. Use progress notes and SOAP patients, at least once daily, and communication sheets.
10. Use printed protocols and guidelines for standard operating procedures/guidelines (SOPs/SOG's).
11. Have a referral - backup system in place and use it when cases become overwhelming. Ask for help!
12. Continue training and knowledge in basic, advanced and supportive care and continue to up-grade.
13. Have a logistics recording system functioning that recover all costs and record all charges.
14. Have a logistics system functioning that will prevent the exhausting of resources and supplies needed.
15. Provide owner emotional support and always show caring and concern for their critical pet.

GUIDELINES - The following general guidelines are divided into assessment, resuscitation, and general
critical care support (1-7). Appropriate treatment of the critical patient can be instituted only if the
patient has been evaluated appropriately. From the time the pet is presented to the hospital to the time it is
discharged primary and secondary exam surveys should be performed frequently.

Triage - In the triage setting the survey should be quickly performed (1,3). It always is done the same.
At other times it is performed in a slower paced setting and more thoroughly, such as after admission into
the CCU (Critical Care Unit) If a life-threatening problem is recognized as the primary survey is done
resuscitative procedures are immediately done without progressing further through the survey. Triage
and multiple daily surveys examine breathing effort and respiratory pattern, abnormal body or limb
posture, the presence of blood or other materials in or around the patient, and any other gross

Primary Survey - Level of consciousness (LOC) is assessed along with airway, breathing, and circulation
effectiveness. If the animal is unconscious the head and neck should be extended to help provide a clear
airway, assuming there are no concerns for a cervical spinal injury. The airway (A) (nose, mouth,
pharynx, and trachea) is checked for patency by looking, listening, and feeling. Recall from basic applied
anatomy and physiology that airway resistance is proportional to the radius of the airway opening to the
fourth power, according to the law of Poiseuille (Q [flow] = πP1-P2r4 / 8nl (8). Therefore with
unconscious patients with the tongue causing a partial obstruction to the rima glottis the head and neck
should be immediately extended and the tongue pulled rostrally. For patients with wheezes a
bronchodilator such as a beta 2 agonist should be administered as an aerosol using a micronebulizer
attached to a oxygen stream.(2,4) If necessary bag-valve mask ventilation can be used to provide forced
assisted ventilation support. This easy to apply technique, in the author's experience, has been on of the

most life-saving procedures he has done for the difficult breathing patient (3-5).

Safety - Appropriate precautions always should be taken when examining a patient’s oral cavity and
oropharynx to ensure no one is bitten. Fingers should never be placed into the mouth of an agonal patient
as this can lead to a serious injury. If there is any chance for a bite a muzzle should be applied or at least
a towel placed over the patient's head (done especially if the nose is bleeding or blocked as a muzzle can
not be placed on these patients). Exam gloves should be dawned if there is any chance of a
communicable zoonotic disease such as leptospirosis. If the patient has blood on him assume its the
owners blood and again gloves should be worn and other body-substance isolation precautions taken.

The presence of increased respiratory effort, paradoxical chest wall movement, abdominal wall
movement with respiration, nasal flare, open mouth, extended head and neck, abducted elbows, and
cyanosis are all indicators of respiratory distress which require immediate treatment. Breathing is
assessed by watching chest wall motion as well as listening to tracheal and lung sounds bilaterally. It is
important to auscult lung sounds bilaterally since the animal may have a significant unilateral
pneumothorax or hemothorax. Lung sounds always should be ausculted prior to listening to heart tones
since the ear is much less discerning of softer sounds once it has adjusted to louder sounds.

Circulation is assessed by checking mucous membrane color and capillary refill time, and ausculting for
heart tones at the same time as palpating central (femoral) pulses (3). Finally assessment and palpation
and examination of the abdomen, flank, pelvis, spine and limbs is carried out during the primary exam
surveys. In the unconscious patient blood flow assessment can be enhanced by the placement of a
Doppler flow probe on the patient's eye and the pulsitile flow assessed. Placement of a Doppler flow
probe on the palmar arterial arch is done in animals that are conscious and blood flow and blood pressure
via an appropriately sized sphygmomanometer. Flow should be easily detected and strong and arterial
BP should be targeted at 100-120/70-90. The venous (blood volume or capacitance) side of the
circulation is assessed by clipping the jugular vein area and assessing how it fills when the vein is
digitally obstructed (3,6,7). The jugular vein should fill within 3-5 seconds and should fill well.
Prolonged filling times >10 seconds definitely indicates poor venous volume and flow requiring volume
or pressure support. A significantly filled vein indicates either a tension pneumothorax. pericardial
tamponade or other cause for venous return to the right atrium. In the trauma patient volume loss can
make it difficult to detect the presence of venous return impairment (6,7).

Secondary Survey - Assessment of the critical patient also involves many other modalities and are
recommended: This includes non-invasive blood pressure monitoring that may progress to direct arterial
pressure monitoring with the placement of an arterial catheter; central venous pressure monitoring; a
CBC with examination of a blood smear and differential; a serum chemistry profile, coagulation panel,

arterial and venous blood gases, lactic acid, urine output and urinalysis, thoracic and abdominal
radiographs and ultrasound assessment; and other techniques. Assessment and monitoring in all critical
patients should also include daily fluid, carbohydrate, protein, and fat intake (12). In the ventilated
patient continuous capnography and SpO2 are considered mandatory (6,7). Ventilatory parameters
(ventilatory rate, peak inspiratory pressures, tidal volume, positive end-expiratory pressure, percent
inspiratory oxygen) should also be monitored.

Resuscitation - If major abnormalities are noted treatment is instituted immediately. For example, if the
animal is found unconscious and not breathing the airway is assessed, the head and neck extended, the
mouth closed over the extended tongue and mouth to nose and mouth rescue breathing should be started.
Use of a BVM (bag-valve-mask) attached to reservoir and oxygen delivered at 10-15 liters per minute is
ideal and if already assembled and ready should be instituted rather than the mouth to nose technique (3-
5). Endotracheal intubation should be followed as soon as possible and ventilation with the use of a bag-
valve reservoir-oxygen system should be started (8). (If the unconscious patient cannot be intubated due
to severe facial or laryngeal trauma an emergent tracheotomy should be performed immediately. An
emergent tracheotomy is performed when the patient is dying due to the lack of a patent airway. The
procedure, which is performed without clipping fur or performing a surgical prep takes less than 60
seconds. In the awake patient with severe upper airway compromise a tracheotomy can be performed
under local anesthetic. An awake tracheotomy can also be used in the conscious or stuporous patient that
requires positive pressure ventilation. In the hemodynamically unstable patient this will avoid the need
for general anesthesia. The respiratory rate should be recorded and the breathing pattern should be
closely observed.

Thoracentesis should be performed bilaterally in any patient in whom there is concern that the patient has
a pneumothorax or a hemothorax (8). This should be done prior to taking chest radiographs since
positioning the patient for radiographs may worsen respiration and may cause the animal to
decompensate. Placement of a chest tube is indicated if negative pressure is never achieved during
thoracentesis or thoracentesis is required more than twice within 2 to 4 hours. Chest tubes should be
placed under sedation and local anesthesia rather than general anesthesia unless control of the patient’s
ventilation is required.

In the absence of blood gases and the ability to assess SpO2 which is very common, if the animal appears
to have any breathing difficulty or shock supplemental oxygen should be provided from the time of
admission. This can be administered by placing tubing from an O2 tank or anesthetic machine in front of
the patient’s nose and mouth and running high flow rates (3 to 15 liters/min) via small tubing. Smaller
patients can be placed in clear plastic bags. The O2 tubing is placed through a small hole in the front of
the bag thus creating an O2 tent. The back end of the bag is left open and the examination can be

completed with the patient in the bag. Supplemental flow-by O2 should be followed by delivery of O2 by
non-re-breathing face mask, oxygen hood, CROWE oxygen collar, nasal, nasopharyngeal, nasotracheal,
or transtracheal catheters or the use of either adult, pediatric or infant bilateral nasal cannula (nasal
prongs) (4). The latter can be placed quickly with a section of tape placed on the device to form a nose-
band then the apparatus is stapled to the patient's face and the loop slipped and tightened behind the
patient's head (4).

In the severely traumatized patient it should be assumed that fractures are present until proven otherwise
and ideally the patient should be restrained to prevent further injury. Restraint should be minimized if the
patient is likely to injure himself further by struggling, if restraint will compromise the airway, breathing
or circulation, or if restraint will cause the patient more pain. If there is concern that the patient may
injure itself further if it is not restrained it may be appropriate to consider sedating the animal. Tape can
be placed over the rostral aspect of the patient at the level of the wing of the atlas, over the cranial thorax
at the level of the scapula and caudally over the wing of the ilium (1,3). Backboards made from Plexiglas
are useful because not only are they sturdy, but the animal can be visualized on all sides, and radiographs
can be taken without having to remove the animal from the board. An example is Whisky White who was
hit by an SUV (7). He sustained a luxation of L2-L3 and became significantly paraparetic. He was placed
on a board almost immediately. He was treated for shock which required oxygen supplementation,
placement of a red rubber feeding tube into the right jugular vein and fluid administration with Oxyglobin
(Biopure, Cambridge, MA), hypertonic saline, hetastarch and plasma. He was intubated with ketamine
diazepam induction and placed on a ventilator. The spine was decompressed and stabilized with two
bone plates. Hyperbaric oxygen was used postoperatively for several days and then was discharged. He
returned 9 days later with acute respiratory failure that was determined to be a diaphragmatic hernia. Near
cardiac arrest occurred requiring rapid open chest resuscitation. He able to be discharged several days
later after the hernia was repaired.

Many severely traumatized patients present with pulmonary injury that worsens rapidly during the early
phase of resuscitation (5,7). Patients with severe pulmonary contusions or ventilatory failure due to
muscle weakness from severe shock may not respond to supplemental O2. A decision should be made to
intubate and artificially ventilate the patient if cyanosis or respiratory distress do not resolve with the
provision of supplemental O2, or if respiratory effort is worsening despite provision of supplemental O2
(8). If arterial blood gases are available positive pressure ventilation should be instituted if the arterial
oxygen tension (PaO2) is less than 60 mm Hg with supplemental O2, or the arterial carbon dioxide tension
(PaCO2) is greater than 55 mm Hg. If the clinician feels confident that a pulse oximeter sensor is
providing accurate readings, and oxygen saturation is less than 90 to 92% on supplemental oxygen, and
there is evidence of respiratory distress, artificial ventilation is indicated.

Rapid control of the airway should be the goal since a prolonged induction may be fatal to the patient (8).
Drugs should be chosen with care as these patients are usually hemodynamically unstable and many
anesthetic agents depress cardiac function and cause hypotension. Ketamine hydrochloride (5 to 10 mg/kg
IV) and diazepam (0.1 to 0.5 mg/kg IV) are ideal for rapid induction and then continued tube acceptance
with the use of pentobarbital 1 mg/kg/hr or a combination of narcotics (oxymorphone hydrochloride h
[0.05 to 0.1 mg/kg IV], or fentanyl citrate i[0.002 mg/kg IV; 30 to 60 mcg/kg/hr infusion]), in
combination with diazepam (0.2 to 0.5 mg/kg IV), and neuromuscular blockers (atracurium besylate [0.25
mg/kg IV; 0.1 mg/kg redose or 180 to 480 mcg/kg/hr infusion]), provides the safest means of maintaining
trauma patients under anesthesia during positive pressure ventilatory support. All anesthetic drugs should
be titrated to effect since patients in shock are much less tolerant of anesthetic agents than healthy
animals and these doses are only intended as guidelines. In general it is recommended to start at 25 to 50
percent of the dose used in a healthy animal.

The priorities with positive pressure ventilation are to correct hypoxemia by maintaining PaO2 greater
than 60 mm Hg and to maintain PaCO2 in the range of 35 to 45 mm Hg (5-8). Initially, positive pressure
ventilation can be instituted using a manually operated AMBU bag; however, since most of these patients
require multiple hours of ventilation therapy while the injured lung tissue heals, mechanical ventilation is
preferred. Peak inspiratory pressures should be kept as low as possible (below 20 cm water) to avoid
iatrogenic damage to injured lung tissue. The use of positive end expiratory pressure will help decrease
inspiratory pressures in the pulmonary injured patient with a high ventilation-perfusion mismatch.
Therefore, if peak inspiratory pressures above 20 cm water are required to maintain adequate O2 levels,
positive end expiratory pressure (PEEP) should be instituted. Positive end expiratory pressure can be
instituted when using an AMBU bag if the bag is fitted with a valve that regulates expiratory pressure.
Positive end expiratory pressure ideally should remain below 10 cm water; however, it should be kept in
mind that even 3 to 5 cm water may lower cardiac output by decreasing venous return to the heart.
Therefore, it is very important to ensure adequate intravascular volume is maintained, and that BP and
urine output are monitored closely. If cardiac contractility is depressed secondary to the trauma or sepsis
positive inotropes may be required (dopamine and dobutamine beginning at 5 mcg/kg/min) along with
continuous direct or indirect blood pressure and continuous electrocardiogram monitoring (6).

Tidal volumes of approximately 10 to 15 ml/kg should be used and the ventilatory rate should be adjusted
to maintain the PaCO2 in the desired range. The trauma patient has increased oxygen demands and PaO2
should ideally be maintained in a high normal range (80 to 100 mm Hg minimum). Oxygen toxicity may
occur within 6 hours of breathing inspired concentrations of 100 percent O2 and levels should be reduced
to below 60 percent as soon as it is feasible. The decision to provide artificial ventilatory support should
not be undertaken lightly. These patients require intensive monitoring and 24 hour care. If a
pneumothorax was present prior to starting ventilation therapy then unilateral or bilateral chest tubes will

be required rapidly since positive pressure ventilation will worsen the air leak (8). Trauma patients on
ventilators may develop pneumothoraces because the added pressure from the ventilation can rupture
injured lung tissue. The lungs should be ausculted bilaterally at least hourly. Any decrease in airway
sounds during auscultation of the thorax, any unexplained decrease in PaO2, or any increase in PaCO2,
may be an indicator of a pneumothorax and thoracentesis should be performed. If blood gases are not
available pulse oximetry and capnometry using an end-tidal CO2 monitor will help evaluate the
effectiveness of ventilator therapy. End tidal CO2 levels should be from 30-45 mmHg and the wave form
should be characteristic of a good flow and exchange of CO2 at the alveolar level.

Assuming no intrathoracic pathology, CVP is a reflection of preload or venous volume returning to the
heart (2). Since adequate cardiac output depends in part on preload, CVP should be monitored as a guide
to fluid therapy. Although normal CVP is reported to vary from between 0 and 10 cm of water, the goal
during resuscitation should be to maintain the CVP between approximately 5 to 8 cm water. The volume
and rate of fluid administration will depend on the patient’s hemodynamic parameters. In general,
hemodynamic parameters should be returned to normal as fast as possible, provided ongoing hemorrhage
is NOT suspected. In this case incremental boluses will be more appropriate with a target of quality flow
but systolic arterial blood pressure kept under 80 mmHg for an hour. The exception ton this may be
profound head injury with cerebral edema suspected (6). If the patient is tachycardic and assessed to be
hypovolemic, fluids should be given until the heart rate returns to close to normal. If pain is suspected as
being the cause of the tachycardia it is recommended to be appropriately treated.

Guidelines for Fluid Administration - If the BP is low or not detectable, fluids should be administered as
fast as possible to return BP to at least detectable (if ongoing hemorrhage at all possible) or to normal as
soon as possible (if not). In my opinion based on clinical experience if the patient is in shock because of
hemorrhage large volumes of crystalloids should be avoided since interstitial edema may result. If the
patient is hypotensive or normotensive and tachycardic, a bolus of a crystalloid of 30 ml/kg is followed
by reevaluation of the patient’s heart rate and BP. If the hemodynamic parameters improve and then
deteriorate, or if they have not improved, a synthetic colloid is administered in slow intravenous boluses
of 5 ml/kg up and give to a total of 20 ml/kg and the crystalloid administration rate is decreased to 3
ml/kg/hr. If the patient stabilizes after the bolus of crystalloid then the crystalloids are continued at
maintenance rates. If the patient has no detectable BP or if the BP is below 50 mm Hg systolic, 6%
synthetic colloids [3 ml/kg] mixed with 23.5% hypertonic saline (1 ml/kg) and this colloid mixture should
be administered at 1-2 ml/kg at a time and each of these boluses are given every 3-5 minutes until 5-6
ml/kg of the mixture total is given. If blood is available it can be substituted for the synthetic colloid or
ideally with an oxygen carrying colloid such as Oxyglobin, a hemoglobin based oxygen carrier (HBOC).
In my experience HBOCs are also beneficial in helping sustain oxygen delivery in situations were blood
loss has not been significant yet perfusion has been a problem such as in gastric dilation-volvulus and

small intestinal perforation-obstruction.

The packed cell volume and total plasma protein should be reevaluated after the first 30 to 60 minutes in
any patient who is not responding to fluid resuscitation or if the packed cell volume is less than 20
percent or has dropped by more than 50 percent of baseline. In these red blood cell transfusion is also
recommended. Since these patients also will be predisposed to a dilutional coagulopathy FFP should be
concurrently administered. If fresh whole blood is available it is the blood product of choice in trauma

Further important information and guidelines concerning fluid support in hypovolemia are briefly listed:
1. E. coli septic shock in dogs causes significant vasodilation that leads to significantly decreased arterial
pressure, cardiac index, mesenteric blood flow, and systemic and mesenteric oxygen delivery & increased
arterial, venous and portal lactate, intramucosal PCO2, PCO2 gap (difference between gastric mucosal
and arterial PCO2), and systemic and mesenteric oxygen extraction ratio. Lactated Ringers given
32ml/kg/hr was able to restore the systemic hemodynamic parameters. However these same LRS doses
were NOT ABLE to correct gut mucosal PCO2 gap (14). It’s important to feed to get flow resumed.
2. Plasma volume decreases in sepsis because of capillary leaks. Hetastarch 6% re-establishes plasma
oncotic pressure and lost plasma volume. Ringer's lactate solution does not (15). Therefore use hetastarch.
3. In pancreatitis, LRS, even at 150 ml/kg failed to achieve a normal value for effective circulating
plasma (ECP) volume, resulting in 100% mortality, where as hypertonic saline was able to achieve ECP
volume.(16) and therefore hypertonic saline should be used as part of the fluid infusion protocol.
4. Limited resuscitation from uncontrolled hemorrhage with hypertonic saline (7.5%) and dextran was
successful in reversing the systemic hypotension, whereas LRS infusion was not able too.(17)
5. Use of saphenous and femoral veins to deliver emergency drugs and fluids only is delayed 1.5 seconds
in cases where the caudal vena caval is compressed, exhibiting the extensive collateral circulation that is
present.(18) Therefore it is very acceptable to use rear legs for vascular catheters is required.
6. Hypertonic saline (7.5%) decreases perioperative weight gain following major surgery compared to
normal saline.(19) Therefore it is recommended to use some hypertonic saline for large cases.
7. Albumin decreases lung cytokines, hydrogen peroxide, and pulmonary edema compared to Ringer's
lactate used in hemorrhage and endotoxemia (20). Therefore give human albumin or plasma if possible.
8. Tissue oxygen levels during severe hemorrhage resulting in MAP of 40 mmHg are less than 20 mmHg
in the liver and deltoid muscle. It is improved with the administration of 100% oxygen following the
shock. Comparing the rapid administrations of either hypertonic saline - dextran (4 ml/kg), LRS (12
ml/kg), and Oxyglobin (6 ml/kg) resulted in the later being the most effective in restoring and
maintaining mean and systolic blood pressure and tissue oxygenation (21). Thus give if possible.
9. Tissue oxygenation levels are improved effectively using low volume resuscitation with Oxyglobin
compared to LRS in severe hemorrhagic shock. To provide "similar" tissue oxygenation and improve

MAP levels from 60-80 mmHg) much more LRS is required compared to autologus blood, LRS with an
equal volume of blood than was anticipated. For a hemorrhage of > 40% of the animals (swine) blood
volume (a 2000 ml hemorrhage) resulting in an MAP of 30 mmHg > 16,000 ml was required of LRS
alone, 4,700 ml for a mixture of autologus blood and LRS, 1500 ml for blood alone, and 450 ml for
Oxyglobin. This low volume of Oxyglobin also reverses low tissue pH and high lactate levels more
effectively than the high volumes of LRS (22). This small amount needed has also been seen in clinical
cases in the author's experience so when possible Oxyglobin is highly recommended to be used.
10. Under acute volume loss peak expansion of vascular volume with LRS is immediate after its infusion
but is only 50% as effective as hetastarch which takes 5 minutes after its completion of its infusion (23).
11. LRS and hetastarch but not plasma resuscitation after rat hemorrhagic shock is associated with
immediate lung apoptosis by the up-regulation of the Bax proteins within mitochondrial membranes.
Hetastarch created less cellular injury than the LRS. Mitochondrial edema was least with plasma and
most with LRS. Cells affected the most are those in the perivascular and peribronchial spaces (24).
therefore try avoid LRS if possible. Hetastarch and plasma are preferred as the major fluids of choice.
12. Use speed and strength of jugular vein filling after digital occlusion and saphenous vein emptying
when raising the leg with the patient in lateral recumbency to determine venous volume and as an
indication of when the "gas tank" or distributive "storing" volume when fluid therapy is provided (3,9).
Central venous pressure may also be used to help establish when the “tank is filled".
13. Use arterial pulse pressure, the difference between systolic and diastolic pressure, as an indication of
stroke volume and the speed of the climb of arterial wave form as an estimate of the force of contraction
(9). Consider the arterial side of the circulation as the "gas line". Not until the gas tank (venous side of
the circulation) is getting low or near "empty" will the gas line not have sufficient volume to provide the
pressure needed to run the system (6). Therefore use venous filling and CVP to determine volume needs.
14. Use of hemoglobin based oxygen carriers (HBOCs) such as Oxyglobin significantly increases brain
oxygen tension in animals with hemorrhagic shock and has been suggested as a fluid of choice when head
injury is also present (25). Therefore use Oxyglobin if possible when patients have head injury.
15. Hypertonic saline is beneficial over normal fluids in patients with head or lung injury by both its
effects on preventing edema and its effects on vascular endothelium. It also helps by improving intestinal
perfusion in both hemorrhagic and endotoxic shock (26-28). It literally pulls fluid out of edema brain
tissue; directly improves regional cerebral blood flow by decreasing endothelial edema; shrinks red cells
making them having more ability to travel through small capillaries; helps in the restoration of normal
intracellular concentrations of sodium and chloride which are low in head and lung trauma which restores
normal membrane potentials; stimulates the release of plasma atrial natriuretic peptide and this peptide
increases blood flow to certain parts of the brain directly and reduces ICP in global cerebral ischemia. It
also causes vasodilation of both systemic and pulmonary vessels and increased cardiac contractility (29).

Other practical protocols - These are widely known but are effective in the care of emergency and critical

patients. They include the following:
1. Saline Enemas – Use these to decrease the fecal load as soon as possible following shock resuscitation
and in cases with foul smelling or blood diarrhea as research has shown an increase in survival in animals
that have a 30ml/kg saline enema after the experimental induction of acute necrotizing pancreatitis (30).
2. Allopurinol – Use at 50 mg/kg PO when possible as its a xanthine oxidase inhibitor and it protects the
stomach, intestine, liver, and pancreas of dogs from damage due to gastric dilation volvulus and other
forms of shock (31). Because it I absorbed via the rectal mucosa, this route might also be used.
3. Pentoxifylline - The use of this xanthine derivative inhibits the production of oxygen radicals of
polymorponuclear neutrophils (PMNs) and their adherence to endothelial cells by inhibiting the
expression of adhesion molecules on the cell surface of the PMNs. It also reduces the production of
inflammatory cytokines, in particular TNF alpha, and prevents platelet aggregation. It also improves
perfusion of the microvascular bed and tissue oxygenation. At a dose of 30-50 mg/kg pentoxifylline has
been shown experimentally to improve the clearance of bacteria and endotoxin and survival from septic
and hemorrhagic shock respectively (32). Therefore when able to, this drug should be give orally ASAP.
4. Hydrocortisone - Stress doses of hydrocortisone have been responsible in helping arrest the need for
positive vasopressors (dopamine, norepinephrine, or epinephrine) in patients in septic shock. The doses
recommended are 1.3 mg/kg as a loading bolus, then 0.18 mg/kg/hr until the shock was reversed and then
0.08 mg/kg/hr. As soon as the underlying infection is under control the steroid dose is decreased slowly
over days. This finding is thought be due to a relative adrenocortical insufficiency (AI) in septic shock.
(34). Therefore if believed that hypotension is due to possible AI then start steroids at low doses.
5. Lidocaine - Ischemia-reperfusion injury in shock is decreased with the infusion of lidocaine at 50
mcg/kg/min after a loading bolus infusion over a few minutes of 2 mg/kg (35). Therefore start this.
6. Methylprednisolone - This rapid acting corticosteroid has a protective effect on dogs in severe
hemorrhagic shock. The mechanism mainly involves the anti-lipid peroxidation activity of the drug.
Positive results were observed in doses as low as 4 mg/kg when given at the onset of fluid resuscitation.
Levels of superoxide dismutase (SOD) remain higher in dogs given methylprednisolone (36). Therefore
one dose of this protector of this membrane stabilizer can be given. The best dose is not yet know yet.
7. Promazine tranquilizers - Contrary to popular belief the use of chlorpromazine has been shown to
enhance microvascular blood flow of the splanchnic circulation in dogs with hemorrhagic shock (37).
Chlorpromazine has also been shown to help prevent acute respiratory distress syndrome in animals
subject to trauma (38). Therefore small doses of 0.01 mg/kg are recommended to be given slowly IV.
8. N-acetylcysteine - At doses of 150 mg/kg given at the onset of fluid resuscitation in hemorrhagic shock
N acetylcysteine preserved splanchnic blood flow and reduced hepatic damage caused by reperfusion
injury as the drug provides glutathione for the replenishment of SOD and has a preservation effect on
hepatic blood flow during shock and resuscitation (39). Therefore it is recommended do give slowly IV.
9. Oxygen - This drug should be given in as high a concentration as possible, preferably near 100%, when
shock is present and some research suggests that it is best given prior to fluid infusion as this leads to less

reperfusion injury than if given after infusion is done (40). Therefore start at least blow-by ASAP.
10. Analgesics - A land mark study proved that pain can contribute to a patient's mortality. In a study
involving human infants that all underwent a reparative cardiac surgery, those that did not receive
constant rate infusions of sufentanil but only received boluses when discomfort actions were noted, had a
23% more death rate over those that received a constant rate infusion of the sufentanil. The "breakout"
pain was associated with higher levels of catecholamines, cortisol, lactate, and vasoconstriction and
increased cardiac outputs and oxygen consumption (41). The authors of that study stopped the study
when it became apparent that pain was the cause of the increased death rate. It is this author's opinion
that both anxiety and pain must be controlled in all emergency or critically ill or injured patients to
provide the most optimal chance for their recovery. Therefore give morphine, hydromorphone or other IV

General Critical Care Guidelines - All critical patients should receive specific assessment and supportive
care also in the following areas: Nutrition (both enteral and parenteral); Fluids and electrolytes;
Gastrointestinal protection and support of liver, pancreas, and kidney function; Musculoskeletal (in the
form of physical therapy; Dermal assessment and protection; Emotional support for the patient, owner,
owners family; Emotional support that also extends to those providing the care for the critical patient. As
a general guideline all patients should receive enteral support within 12 hours of hospital admission.

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