CHAPTER 20 Heather Darbo and Cheryl Page Lakeshore Veterinary Specialists, Glendale, Wisconsin Critical thinking is the intellectually disciplined process of skillfully conceptualizing, analyzing, synthesizing, and applying information that is generated by observation, experience, reflection, reasoning, and communication. An understanding of physiology, a basic knowledge of drug action, and a keen sense of observation combine to create the critical thinking skills required for critical care nursing. The responsibility of the critical care veterinary nurse (also termed technician or nurse technician) is to work as part of a cohesive healthcare team for the benefit of the patient. A systematic approach is essential and the Rule of 20 provides an organized framework for evaluating the patient, anticipating potential complications and recognizing important changes in clinical signs. The veterinary nursing staff also serve as advocates for the animals in the ICU. Veterinary medicine is very poignant in this regard since the animal patients cannot advocate for themselves. The nursing staff must be conscientious about the therapy being delivered and often need to tailor the process to the individual patient based on their underlying disease process and their tolerance of handling. In addition, it is important to care for pet owners, providing updates on the condition of patients or extending a caring hand whenever possible. Other duties of the critical care nursing team will include oversight of equipment maintenance as well as development and implementation of hospital and patient care guidelines. Appropriate and compassionate nursing care can play a vital role in patient recovery from illness. A hospital ready area is essential to provide care for patients experiencing critical and potentially life‐threatening situations. A ready area should be prepared for incoming patients in a location with easy access for team members (Figure 20.1). A gurney placed near the entrance of the hospital should be available for safe transport of patients. Figure 20.1 (a) Hospital ready area. Good lighting and central access to equipment and supplies in this area are essential. An examination table can be reserved for emergent patients, with dosing charts, crash cart with supplies (see Table 20.1), materials for IV catheter placement, oxygen source and delivery supplies, monitoring equipment (ECG, ETCO2, pulse oximeter, blood pressure supplies), suction device with Yankauer and whistle‐tip apparatus, defibrillator, and AMBU bags all close by. (b) Example of contents that can be located in the first three drawers of a crash cart. The first drawer focuses on airway and breathing, the second on circulation, including medications. Table 20.1 Common fluid calculations used when caring for the critical patient. *% dehydration can be estimated as noted in Chapter 2, Table 2.2. The ideal location for a ready area will vary between hospitals; in a large ICU, it should be centrally located so that access is maximized for all patients. Additional ready areas may be warranted in sections of the hospital where critically ill patients are kept or where procedures involving sedation or anesthesia are performed. The crash cart should contain all the items required to perform both external and internal cardiopulmonary resuscitation (CPR) (Box 20.1) It is important that the hospital ready area(s) be well maintained; it must be adequately stocked with necessary supplies and associated equipment and the equipment must be regularly tested for proper function. Ideally, the ready area should be audited twice per day. A check‐off list should be created to ensure thorough daily evaluation, and all team members should be aware of the available supplies. If the readiness area is utilized, it should be a priority to return it to its ready state as soon as possible. The training of new staff members is another important aspect of preparedness. New members of the team can be oriented to the location and purpose of the ready area. Once oriented, they can be assigned to daily inventory duties so that they become familiar with it. An established staff member should be available to provide guidance when necessary. New staff members should be trained in veterinary CPR and established team members should review CPR on a regular basis to maintain cognitive and psychomotor skills. An easy job for inexperienced staff members is the recording of events and drugs during CPR. Figure 20.2 shows an example of a CPR recording sheet. Figure 20.2 Standard case report form for veterinary small animal in‐hospital CPR events. ALS, advanced life support; Atr, atropine; AW, airway; Brady, severe bradycardia; CPA, cardiopulmonary arrest; DEFI, defibrillation; Econo, economic; Epi, epinephrine or adrenaline; ET, endotracheal; ETCO2, end‐tidal carbon dioxide; J, joules; Loc, location; MRN, medical record number; OPEN?, was open‐chest CPR administered? PEA, pulseless electrical activity; ROSC, return of spontaneous circulation; Vaso, vasopressin; VF, ventricular fibrillation; VT, pulseless ventricular tachycardia. Source: Boeller M, Fletcher DJ, Brainard BM, et al. Utstein‐style guidelines on uniform reporting of in‐hospital cardiopulmonary resuscitation in dogs and cats. A RECOVER statement. J Vet Emerg Crit Care 2016;26(1):11–34. Used with permission from Wiley. Cardiopulmonary resuscitation training should include “mock code” situations, which provide invaluable practice for an uncommon and potentially intimidating situation. It is vital to be as realistic as possible when setting up these training situations. The practice session can begin by announcing “code to [hospital area]”. As staff arrive, a CPR team leader is established and staff members are assigned to particular jobs such as chest compressions, catheter placement, intubation and respiration, drug administration, recording, and time keeping. Once the code is complete, the team leader and participating staff should have a debriefing session, where the CPR efforts are discussed. The debriefing allows everyone to assess the response to the event both as a team and their individual responses. Chapter 11 discusses how to perform CPR in more detail. Every patient that is hospitalized should have a preselected CPR code from the owner, such as red (do not resuscitate), yellow (noninvasive resuscitation), and green (all resuscitative efforts including thoracotomy if required). This should be clearly identified on the patient’s treatment sheet and cage. If a cardiopulmonary arrest is identified, CPR should be initiated without delay (see Chapter 11). Chest compressions are initiated, while the team is called to the scene. Nursing duties during CPR can be quite varied. Tasks such as contacting the pet owner, performing chest compressions, endotracheal intubation, ventilation, placement of an IV catheter, drug administration, defibrillation, and recording may be assigned to the veterinary nurse. An experienced technician may even lead the CPR efforts when appropriate. Triage is the art of prioritizing patients and their treatments based on the severity of their illness. This is an emergency room concept that can also be applied in the ICU environment. When arriving on shift, the ICU nurse technician will review the ICU census sheets, scan the individual treatment sheets, make a general evaluation of each patient, and then triage the patients. Nursing rounds provide vital information used for patient triage and can be done at shift change. At this time, the nurses going off duty can help to prioritize, advise, and direct the oncoming staff regarding patient requirements, treatments, and potential for complications. Organizing the needs of each patient during rounds allows the technician to make decisions on how to effectively accomplish each of the required tasks. At this time, nursing personnel can be allocated based on the skill level of each member. Prioritizing the needs of each ICU patient will assist in ensuring that the most critical patients are cared for by the most experienced staff. During cage‐side rounds, each treatment sheet and cage card can be reviewed for content, accuracy, and CPR code status. The general physical status of each patient is assessed by reviewing their vital signs and performing a brief physical examination. The veterinary nurse technician will auscultate the thorax, assess pain using the pain scale adopted by the hospital (see Figures 19.2 and 19.3 for an example) and note oral intake, frequency and consistency of urination and defecation, mentation, level of consciousness, and ability to stand. Patients with identified abnormalities of airway, breathing, circulation, level of consciousness or level of pain should be placed strategically in the ICU where they will be observed frequently by all staff members and are treated first. Those with a potential for an impending problem (such as seizures or airway obstruction) should have drug doses precalculated and intervention equipment, such as a laryngoscope and ET tube, set up by the cage. Patients who have transmissible disease should be placed outside of the main flow of traffic and isolated from other susceptible patients. When using restraint, it is important to determine how much is necessary and whether physical or chemical restraint will be needed to keep everyone safe. A variety of muzzle types and styles made from cloth, plastic or coated wire are commercially available for both dogs and cats. The specific type of muzzle used in a given situation will depend on the patient and disease state. For aggressive animals that cannot be handled without heavy sedation or anesthesia, initial contact may only be possible by administering a sedative that has transmucosal absorption (such as ketamine or buprenorphine) into the mouth or an IM or SC injection of a short‐acting anesthetic or tranquilizer. This type of patient should have an Elizabethan collar or cage muzzle placed to protect personnel. A long intravenous fluid line (with extension sets) is attached to the catheter with an injection port located outside the cage for easy access. Direct handling of the animal may be minimal. Treatments and diagnostic procedures for the aggressive patient are prioritized and grouped together with all drugs and equipment ready. This enables everything to be done at the time of sedation, minimizing stress for the patient and protecting the staff from potential injury. The Rule of 20 provides an organized method to evaluate the vital parameters of the small animal ICU patient and anticipate potential complications in preparation for intervention. Many patients enter the ICU with one set of problems but develop additional concerns or complications during their hospitalization. Nursing notes should be recorded on the medical record or treatment sheet, not only by checking off boxes but also providing a brief but detailed description of the nurse–patient interaction. Recording the times that a treatment is performed and medications administered (Figure 20.3) is important information that will document patient care. Typically, there will be some “default” recommendations for every patient, such as checking an IV catheter every 1–2 hours, daily body weight, and monitoring vital signs (TPR) every 4–6 hours. It is important to group treatments and monitoring procedures together to minimize the handling of the critical patient and utilize nursing staff efficiently. By using the Rule of 20 for nursing care, the staff can prioritize the needs of each patient and provide a balanced approach to patient care. Figure 20.3 Example treatment (a) and nursing notes sheet (b). Used with permission from Lakeshore Veterinary Specialists. The fluid balance in the intravascular (perfusion) and interstitial (hydration) fluid spaces is one of the most important parameters to monitor and maintain in the critical patient. Volume overload can be as detrimental as insufficient fluid volume when the patient has heart or lung dysfunction. Providing fluid therapy is a key component of the care provided in the ICU. Suggestions for IV catheter maintenance and care are provided in Box 20.2. Fluid infusion involves: Figure 20.4 Fluid additive label. These should be permanently affixed to a fluid bag. Source: United Ad Label, Grand Island, NY. Used with permission. Often multiple IV lines, tube feeding lines, and a series of pumps are assigned to one patient and must be appropriately labeled. Considerations for fluid therapy in the ICU are discussed in Box 20.3. Formulas and techniques for providing a constant rate of infusion (CRI) for drugs or supplements are provided in Box 20.4. Once fluid therapy has been initiated, the ICU nurse is assigned the task of monitoring the rate and volume of infusion, as well as the effects of the therapy on the patient. Fluid input should be based on calculated fluid requirements, and reassessed on a regular basis (Table 20.1). Changes in the patient physical peripheral perfusion parameters (heart rate, mucous membrane (MM) color, capillary refill time (CRT), pulse quality) and body temperature often provide the earliest indication of changes in the perfusion and fluid balance. Physical examination findings that reflect the perfusion and hydration status of the patient are listed in Tables 2.1 and 2.2 in Chapter 2. Equipment‐based monitoring tools and the results that should trigger concern for decompensation due to fluid imbalance are also discussed. Insufficient fluid balance can result in hypotension and dehydration, which can result in tissue hypoxia. Excessive fluid infusion can cause volume overload with third body fluid spacing and peripheral, lung or brain edema. Nursing orders are generally carried out every 1–2 hours. Each time a treatment is performed on a patient, the IV fluid infusion rate(s) is rechecked to ensure proper delivery of the prescribed fluids. The fluid line is examined from fluid bag to catheter, as well as examination of the catheterized limb to ensure proper function. The assessment of the fluid balance over time (24 hours) is dependent upon the quantification of the amount of fluids taken in compared to a careful estimation of the amount of fluids that go out. This should be recorded on the patient flow chart with a progressive total of the volumes noted every 2–4 hours. Fluid input includes oral, IV, tube feedings, and retained irrigants. Fluid output will include urine, wound/tube drainage and loss through vomiting and diarrhea. Voluntary intake should be measured before and after each meal or when fluid is offered. Output can easily be measured if a urinary catheter is in place, with normal urine output in the canine and feline being between 1–2 mL/kg/h. Estimation of the amount of urine in the litter box or excreted on a pad can be made by weighing the material before and after it is placed in the cage. The added weight in grams is approximately the total number of milliliters of urine produced (does not include evaporation). Assessing the blood volume within the core circulation is an ongoing challenge for the critical care team. The trend of change in the central venous pressure (CVP) can represent the changes in the fluid volume in the central veins in the absence of right heart failure, pneumothorax, mechanical ventilation or pericardial effusion. Normal CVP is 0–5 cmH2O. The target CVP in a patient with normal heart function may be as high as 8–10 cmH2O. A trend of change deviating from the targeted CVP should be reported. CVP measurements can be performed by visual assessment of the pressure with a water manometer or by attaching the manometer to a pressure transducer for an electronic reading. Obtaining and recording a baseline blood pressure at the time of admission should be standard of care in the small animal ICU. The consequences of either hypotension or hypertension are detrimental to the critical patient, requiring immediate plans for intervention. There are two techniques for measuring the blood pressure: direct arterial pressure monitoring using an arterial catheter and indirect blood pressure measurement. Monitoring the arterial pressure by the direct method has been the “gold standard” for blood pressure measurement, but it is often not used because of the difficulties in placing and maintaining arterial catheters [3]. A skilled veterinary nurse must place the arterial catheter into one of the peripheral arteries (such as the metatarsal or femoral artery). Most advanced multiparameter monitoring devices (such as SurgiVet®, Waukesha, WI) have a pressure transducer that is connected to the catheter and a monitor to display the systolic, diastolic, and mean arterial pressure numbers as well as the pressure waveform. Materials needed for monitoring direct arterial blood pressure are noted in Figure 3.2, with the supplies and technique for placing and maintaining an arterial catheter in Box 3.2A and Box 3.2B. The steps for measuring the direct arterial blood pressure are listed in Box 3.3. Noninvasive techniques are more common using an automated oscillometric device or a Doppler ultrasound flow detector. The most common locations to place the Doppler are the palmar arterial arches of the forelimbs and hindlimbs [3], while the tail and pedal arteries can also be used. General guidelines for obtaining indirect blood pressure measurements are provided in Table 3.3 and Figure 3.4. The blood pressure cuff should be 40% of the circumference of the limb being used. When the cuff size is too small, a false elevation in blood pressure will be obtained. Too large a cuff will provide an inaccurate and lower pressure. The blood pressure should be recorded, noting the position of the patient, the extremity used, and the cuff size to ensure repeatable results. Any variation in these factors can change the blood pressure values obtained. Standard protocol for measurement of noninvasive blood pressure using the American College of Veterinary Internal Medicine consensus statement is noted in Table 3.3, the necessary equipment pictured in Figure 3.4, and the validation criteria listed in Box 3.4. With every blood pressure measurement, a heart or pulse rate is taken and the results interpreted together. Profound tachycardia can elevate the blood pressure to within a “normal” range in a patient that is unstable and requires IV fluid support. In addition, monitoring the trend of change over time is more important than any single value. Hypotension in a patient that has bradycardia can require different therapeutic intervention than that prescribed for hypotension with tachycardia. Physical examination findings associated with shock are listed in Table 2.1, and further discussion on blood pressure appears in Chapter 3. Oncotic pressure (or colloidal osmotic pressure (COP)) is the osmotic pressure exerted by colloids in solution. In the vascular system, the major contributor to the COP is albumin. These large molecules cannot easily pass out of the intravascular space and attract water, maintaining the intravascular fluid volume. Patients at risk for a decrease in the intravascular COP will be prone to fluid shifting from the intravascular to the interstitial space, resulting in peripheral edema (such as conjunctival, hock, facial) and intravascular volume deficits. Clinical signs of low blood protein concentrations are noted in Table 4.3. The total protein (TP) value from the refractometer can be a rapid and easy means for early identification of changes in blood protein levels. The physical peripheral perfusion parameters are assessed frequently in patients with concern for a low COP for early signs of hypovolemia and poor perfusion. Decreased albumin production, increased albumin loss, and dilution of plasma proteins with protein‐free fluids are all potential causes of a decline in TP and COP. A list of common problems in the small animal ICU patient associated with an altered albumin concentration is presented in Table 4.4. A search for the underlying cause and administration of a synthetic or natural colloid should be pursued. Advantages and disadvantages of synthetic and natural colloid infusion are outlined in Table 4.6 and Table 4.7. A plasma transfusion or administration of canine albumin requires careful monitoring for any signs of a transfusion reaction (Figure 20.5). Figure 20.5 An example template to monitor a patient receiving a transfusion. Used with permission from Lakeshore Veterinary Specialists. The small animal ICU patient can experience either hypoglycemic or hyperglycemic episodes, each with their own potential consequences. Monitoring the blood glucose is therefore essential, especially when the underlying problem is known to cause alterations in blood glucose (such as diabetes mellitus, pancreatitis, prolonged seizure activity). Glucose supplementation is an ongoing part of the treatment plan when the patient has liver dysfunction, anorexia has been prolonged or the patient is young. The amount of blood drawn should be minimized, with the blood used for other tests as well when possible (Table 20.2). The type of glucose analyzer used (such as glucometer, chemistry analyzer, blood gas/electrolyte analyzer) will determine the volume of blood needed, with serial samples best analyzed on the same equipment. Point of care glucometers require small sample volumes, allowing blood to be collected by ear‐prick techniques when desired. It must be noted whether the blood glucose sample was taken during fasting or the period of time since feeding. Table 20.2 Considerations for minimizing blood loss from multiple phlebotomies. Patients with hypoglycemia will require IV glucose (typically in the form of dextrose) supplementation. Dextrose is supplied as a 50% solution and is usually diluted prior to administration. However, patients exhibiting seizures, tremors or severe hypotension due to hypoglycemia can require emergent intervention with 0.5 g/kg dose of 50% dextrose. It is better to dilute the solution to 25% for IV bolus administration when possible. The high osmolarity of glucose can cause phlebitis or, if infused outside the vein, perivascular necrosis. Dextrose is not to be administered subcutaneously at any time as the resulting hyperosmolarity may lead to tissue necrosis. Dextrose that is administered as a CRI should be infused through an IV catheter (peripheral or central). Dextrose is most commonly diluted in crystalloid fluids and administered at a concentration between 1.25% (1.25 g/100 mL) and 5% (5 g/100 mL). A buretrol (Baxter Medical, Deerfield, IL) can be used when short‐term dextrose supplementation is anticipated or the concentration of dextrose is likely to change after a few hours. Should a concentration be required that is >5%, it should be administered through a central line. Catheter sites are monitored for signs of perivascular edema or tenderness. Hyperglycemia associated with diabetes mellitus will necessitate insulin therapy. A CRI of regular insulin is commonly used to initially treat diabetic ketoacidosis or hyperosmolar nonketotic diabetic crises. Frequent assessment of blood glucose is required by collecting blood every 1–4 hours or by placing an interstitial glucose monitor. Adjustments are made to the insulin dose as indicated (see Chapter 5). Alterations in blood sodium (Na), potassium (K), ionized calcium (iCa), magnesium (Mg), chloride (Cl), and phosphorus (P) can have important consequences. Causes of specific electrolyte disturbances that commonly occur in the small animal ICU patient are listed in Tables 6.1, 6.2, and 6.3. The clinical signs can be variable and are noted for the specific electrolyte in Table 6.4. The acid–base balance is affected by the electrolyte status and should be assessed by blood gas analysis when an electrolyte disorder has been identified. Blood should be collected in a lithium heparin or serum separator tube. The EDTA anticoagulant in lavender top tubes can alter the K and iCa concentrations. The acid–base analysis must be run immediately after blood collection or the sample stored on ice should a delay in testing be necessary. The procedure for collecting an arterial sample is outlined in Box 8.1. Any residual air in the syringe should be expelled, an air‐tight cap placed and the sample stored on ice when transport for analysis is required. Alterations in blood Na and the treatment for the Na disorder can each cause severe and permanent brain damage when blood Na changes too rapidly. Correction of the Na imbalance begins once perfusion has been restored. The blood Na should be restored to a normal range slowly, at a rate ≤0.5 mEq/h (see Chapter 6). Hyperkalemia will prolong myocardial cell repolarization, causing ECG changes and affecting perfusion. Medications used to immediately correct the effects of severe hyperkalemia are listed in Table 6.5. Calcium gluconate is infused when clinical signs of hypocalcemia are diagnosed. The ECG is closely monitored when treating hyperkalemia or hypocalcemia, with the electrolyte status rechecked to guide the need for further therapy. Fluid diuresis can result in hypokalemia, causing weakness, ventral flexion of the neck and, if severe, impaired ventilation. Box 6.4 provides a sliding scale for supplementing replacement crystalloid solutions with potassium chloride to prevent hypokalemia associated with IV crystalloid therapy. Oxygenation describes the ability of the red blood cell to pick up oxygen from the alveoli and transport it to the cell. It is reflected by the PaO2 and by the saturation of oxygen (SaO2) from the arterial blood gas and the SpO2 reading from the pulse oximeter. Ventilation describes the ability of the body to expel carbon dioxide (CO2). It is reflected by the PaCO2 on the arterial blood gas and the end‐tidal CO2. Providing a patent airway and ensuring adequate breathing are the first two important interventions in any crisis. The ready area (see Box 20.1, Figure 20.1) will have endotracheal tubes of varying sizes, ties, laryngoscopes, an AMBU bag, and oxygen source available for immediate use. Cage‐side oxygen can be delivered through an oxygen cage, oxygen collar or nasal cannula(s) (Box 20.5). Patients with oxygen cages require close monitoring of the environmental temperature, humidity, and concentration of oxygen and CO2 (see Figure 8.6, Figure 8.7).
Veterinary nursing care
Introduction
Preparedness
Parameter
Calculation
Daily maintenance fluid requirements
(kg0.75) x 70 (mL/day)
OR
2–4 mL/kg/h (40–60 mL/kg/day)
Daily replacement fluid requirements
% dehydration* × 0.6 × kg
Daily ongoing fluid requirements
Estimate volumes (mL) lost through tubes, urine, diarrhea, etc.
Daily total fluid requirements
Maintenance + ongoing + replacement
Calculation for drips/sec for manual fluid administration
(mL/h rate) × (#drops/mL)/3600 (sec/h) = # drops/sec
ICU nursing priorities
The Rule of 20 for nursing care
Perfusion status and fluid balance
Blood pressure
Oncotic pull and albumin status
Glucose
Consideration
Rationale
Site of blood collection
Choose vein away from diseased body areas and for optimal patient comfort
Monitoring several parameters
Group requested blood tests together for one blood draw to minimize number of venipunctures
Coagulation status
Use peripheral veins and bandages to minimize hematoma formation in critical body regions
Multiple or repeated blood samples required
Place a catheter to use for blood withdrawal or use an interstitial monitor for glucose
Site and repeated samples
Keep at least one peripheral vein free of venipuncture for IV catheter access should it be required
Patient restraint/sedation
Provide adequate restraint or light sedation to minimize discomfort and complications
Glucose samples
Collect blood from ear veins to save peripheral veins; collection can be done by one person (Figure 5.3). Or consider interstitial monitor instead (Figure 5.4)
Volume of collection
Withdraw the minimal amount of blood needed to run necessary tests
Technique of collection
Use the three‐syringe technique with using sampling catheters (Box 10.2)
Apply temporary bandage afterwards
Use to minimize hematoma formation and blood loss
Electrolyte and acid–base status
Oxygenation and ventilation
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