Page 442 - Clinical Small Animal Internal Medicine

410 Section 5 Critical Care Medicine

The use of blood products in shock resuscitation is not Table 41.1 Dosages of commonly used opioid analgesics
VetBooks.ir routine since most patients have adequate oxygen‐carry­ Drug Dosage Frequency
in the patient with shock
ing capacity. If a patient has been administered an ade­
quate volume of fluid for resuscitation, has persistent
clinical signs of shock and requires oxygen‐carrying
capacity, then the administration of blood is indicated. Fentanyl (bolus) 2–5 μg/kg PRN, q15 min
This can be in the form of packed red blood cells, whole Fentanyl (CRI) 5–20 μg/kg/h CRI
blood or hemoglobin‐based oxygen carriers. No agreed‐ Hydromorphone/ 0.05–0.2 mg/kg q4‐6h
upon transfusion trigger exists and the decision to oxymorphone
administer blood depends on the chronicity of the ane­ Morphine 0.5–2 mg/kg q4h
mia and the patient’s clinical signs. For patients with an Buprenorphine 0.01–0.02 mg/kg q6‐12h
acute drop of 30–50% in packed cell volume (PCV), the Methadone 0.2–0.5 mg/kg q4‐6h
administration of blood should be strongly considered.
In these cases, a reasonable goal is to raise the PCV by CRI, constant rate infusion; PRN, as needed (pro re nata).
15–20% with a minimum PCV target of 20%. Typical
doses of 10 mL/kg of packed red blood cells or 20 mL/kg Administration of vasopressors or positive inotropes
of whole blood should be effective. should not be performed prior to adequate volume
The actual rate of administration of blood products for expansion, with the possible exception of treating car­
resuscitation will depend on the patient’s condition. diogenic shock due to systolic failure with a positive
Under ideal circumstances, blood products are adminis­ inotrope. Clinically, the most frequently used vasopres­
tered slowly with careful monitoring for transfusion sor during shock is epinephrine administered for the
reactions. Patients in shock, however, do not often have acute treatment of anaphylaxis. A more detailed discus­
the benefit of time and bolus administration may be sion of vasopressors can be found in Chapter 43.
needed. In this case, care has to be taken as techniques Some patients in shock will not be stabilized until the
that apply pressure to the red blood cells or increase underlying disease process has been corrected, as is
shear stress, such as administration with an infusion bag often the case with obstructive shock. Patients with sig­
through a small‐bore catheter, can result in significant nificant amounts of pericardial effusion causing cardiac
lysis of transfused cells. When bolusing blood products, tamponade improve dramatically when even a small
it is best to allow blood to flow by gravity as quickly as amount of fluid is removed, as do patients with GDV fol­
possible. Administration of blood should be through a lowing decompression of the abdomen. Patients in
dedicated IV catheter, meaning that other resuscitative obstructive shock often do not have an absolute volume
fluids should be held during transfusion unless provided deficiency, but increasing preload can transiently
through a different catheter or lumen (in the case of mul­ improve the diastolic filling of the heart while prepara­
tilumen catheters). It is safe to administer normal saline tions for definitive treatment are under way.
with blood products and co‐administration may improve
the fluid dynamics of the blood product and speed the
delivery rate. Reevaluation and Endpoints
The treatment of pain may be needed in many patients of Resuscitation
with shock, and is mandatory if they have been trauma­
tized. In unstable painful patients, pain control should be The importance of reevaluating the patient during and
achieved with short‐acting pure mu opioid agonists (ex. after resuscitation cannot be overstated. When evaluat­
fentanyl, hydromorphone, oxymorphone or morphine) ing the efficacy of treatment, the clinician expects physi­
administered via the intravenous or intramuscular route. ologic signs of shock to resolve. If resolution is not
The dose should be adequate to effectively treat pain but achieved, further resuscitation is needed or reconsider­
not depress respiration. This will help the clinician eval­ ation of the diagnosis is necessary. As with all medical
uate the patient, as it will mitigate the contribution of treatments, it is necessary to have predetermined end­
pain to tachycardia. With pain controlled, the presence points in mind to decide when treatment is no longer
of tachycardia likely indicates shock or hypoxia in the needed. The optimal endpoints of resuscitation have
traumatized patient. Typical doses of common analge­ been debated for a number of years and although rec­
sics are provided in Table 41.1. ommendations and general agreement exist, no consen­
Vasopressors and positive inotropes are rarely used sus has been reached. The ultimate endpoints of
during the initial resuscitation of shock but can be resuscitation should tell the clinician when the patient
invaluable for the treatment or management of vasodi­ is out of shock, meaning adequate oxygen delivery to
latory or septic shock that is refractory to resuscitation. all tissues has been reestablished. Possible endpoints