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Critical Care—The Overview
Critical Care
0195-5616/89 $0.00 + .20
Critical Care-The Overview Rebecca Kirby, DVM*
Critical care is the stabilization, diagnosis, monitoring, and definitive therapy of the patient with catastrophic or life-threatening problems. Presentation can be as an emergency patient with an acute illness, as a chronically ill patient that has decompensated, or as a hospitalized patient that has developed unexpected serious complications. All postoperative patients are considered critical care patients until life-threatening anesthetic or surgical complications are ruled out. Catastrophic problems (airway obstruction, respiratory failure, and circulatory failure) lead to death within seconds if left untreated. Life-threatening complications allow more time for stabilization and usually involve one or more of the following four organ systems: cardiovascular, respiratory, urinary, and nervous systems. The acutely ill patient presents a special challenge because the underlying diagnosis may not be known during the first 24 to 48 hours of hospitalization, when critical decisions must be made. The diagnostic, monitoring, and therapeutic procedures must be coordinated with a coherent, prioritized approach as the patient moves from the emergency 'situation to surgery or diagnostic procedures and then finally to the critical care area. This requires a problem-oriented approach, with a "temporary problems" list compiled upon admission from the history, physical findings, and minimum database. Diagnostic, therapeutic, and monitoring plans are eutlined for each problem (Fig. 1). The hospital orders are derived from this outline. The patient's most life-threatening problem is listed first and managed before proceeding with less necessary diagnostic and therapeutic procedures. The problems list and prioritization are revised as changes occur in the patient's condition. Variables that contribute to the overall success of patient resuscitation are listed in Table 1. Therapeutic failures do not generally result from ignorance but rather from failure to act expeditiously at a crucial moment. Therapy must be provided at the right time, in the right amount, and in the right order.
*Diplomate, American College of Veterinary Internal Medicine; Charter Diplomate, American College ofVeterinary Emergency and Critical Care; Director, Emergency Services, Veterinary Hospital, and Assistant Professor, Emergency Medicine, University of Pennsylvania School ofVeterinary Medicine, Philadelphia, Pennsylvania Veterinary Clinics of North America: Small Animal Practice-Val. 19, No.6, November 1989
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Emergency Service Initial Treatment Sheet Temporary Problem List Diagnostic Plan Therapeutic Plan Monitoring Procedures
Figure l. Temporary problems list format. ProW ems are listed in order of priority, with the most life-threatening problem listed first. Diagnostic, therapeutic, and monitoring plans are listed for each problem.
TRIAGE Triage is the art of prioritizing the patients and their problems upon presentation to the hospital. This initial assessment determines waiting time for the emergency patient before complete examination and therapeutic intervention. During triage, a brief summary of the owner's primary complaint and the time of onset are obtained. The animal is removed from the carrier or towel and quickly examined for abnormalities listed in Table 2. Significant changes from normal require that the patient be taken directly to the treatment area.
Table 1.
Factors Affecting Successful Patient Resuscitation
Primary illness or injury Amount of fluid or blood lost Patient age and previous health Number and extent of associate9 medical conditions Time delay in instituting therapy Volume and rate of fluid administration Choice of fluids: crystalloid, blood components, or synthetic colloids
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Table 2.
Physical Parameters Assessed During Triage
Active hemorrhage Labored or questionable breathing patterns Rapid shallow breathing-Suspect pleural space disease Loud breathing-Suspect upper airway disease Labored inspiration/expiration-Suspect lung parenchymal disease Prolonged forced expiration-Suspect small airway disease Mucous membrane color-Color other than pink is abnormal Capillary refill time (CRT)-Greater than 2 seconds or less than A to 1 second is abnormal Pulse rate Dogs-Less than 60 and greater than 200 beats per minute are abnormal Cats-Less than 150 and greater than 250 beats per minute are abnormal Fractures-Open or unstable and likely to cause soft tissue damage Altered mentation-Seizures, uncontrolled hyperexcitability, stupor, coma Open wounds
In addition to the presence of abnormal physical parameters, there are several historical or observed problems that warrant immediate triage to the treatment area. These include: Trauma Profuse diarrhea Urethral obstruction Labored breathing Seizures Loss of consciousness Excessive bleeding History of poisoning Prolapsed organs Potential snakebite
Heat prostration Open wounds exposing extensive soft tissue or bone Shock Anemia Burns Dystocias Expired animals (for the client's benefit)
Rapid physical assessment of patient stability and prioritization of problem.s are also performed each time a critical patient is monitored within the intensive care unit (ICU). Specific problems such as profuse diarrhea, urethral obstruction, labored breathing, excessive bleeding, hyperthermia, or loss of consciousness alert the clinician or nurse that life-threatening complications are imminent. These animals are then "triaged" as high-priority patients within the ICU, and therapeutic and monitoring efforts are intensified.
MANAGEMENT OF CATASTROPHIC PROBLEMS Airway patency, oxygenation, ventilation, and tissue perfusion are the main areas of concern during triage. Airway obstruction, apnea or ineffective breathing, and circulatory failure lead to catastrophic problems, with all tissues compromised; multiple organ failure results, with death the final complication. Assessment and management of airway, breathing, and circulation in critical patients are similar, regardless of the underlying diagnosis. Airway patency is first assessed and steps taken to clear obstructions through intubation or tracheostomy (see Paddleford and Harvey). Oxygen and ventilatory support are provided (see Hendricks). When the heartbeat is absent, immedi-
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ate cardiopulmonary cerebral resuscitation is initiated (see Robello and Crowe). The presence of a heartbeat with circulatory failure warrants examination of cardiac function and rhythm as well as blood pressure (see Fox). Hypovolemic or hemorrhagic shock requires aggressive fluid and/or blood component therapy. Blood pressure support may be indicated, once intravascular fluid volume has been replaced. Cardiogenic shock requires reduction of cardiac preload and afterload. Myocardial contractility is supported or pericardia! effusion drained, as necessary. Septic shock is managed through intravascular volume support, drainage of septic foci, and administration of appropriate antibiotics (see Goodwin and Schaer). Reperfusion injury causes tissue and cellular damage through the production of oxygen free radicals and increased intracellular calcium, sodium, and water (see Muir). Fluid, electrolyte, and acid-base imbalances result, requiring assessment and stabilization (see Garvey). All tissues of the body are affected by ischemia-reperfusion, with the kidneys severely affected. Renal function must be aggressively monitored and therapeutics employed at the first sign of compromise (see Kirby). Capillary stasis and tissue hypoxia predispose to sludging of blood, increased capillary permeability, and platelet aggregation. Intravascular consumption of clotting factors can result in significant bleeding (see Wingfield and VanPelt) Intensive monitoring techniques are employed to detect early signs of decompensation (see Haskins), with concentrated efforts given to the four critical organ systems, abnormal bleeding, and sepsis. The pivotal point of therapy during resuscitation is protection of brain function. The status of brain function will determine the quality of life subsequent to recovery. Repeated 'neurologic examinations and therapeutics to · reduce intracranial pressure are vital to long-term patient survival (see Dayrell-Hart and Klide).
LIFE-THREATENING PROBLEMS Life-threatening problems allow more time for resuscitation but progress to catastrophic problems if left untreated. Many are identified through triage, whereas others are suspected from historical, physical, or database findings. Most life-threatening problems involve one or more of the following four organ systems: respiratory, cardiovascular, neurologic, and urinary systems. Respiratory System Abnormal breathing may be due to pathology anywhere along the respiratory tract, including the nasopharyngeal region, larynx, trachea, bronchi, bronchioles, and lung tissue. Trauma is a major cause of abnormal breathing, resulting in pneumothorax, pulmonary contusions, fractured ribs, ruptured bullae or airways, and/or pleural hemorrhage. It must be recognized that breathing problems may not be evident for 12 to 72 hours post-trauma. Other causes of labored breathing include fluid accumulation within the pleural space, asthma, mass lesions, pneumonia, airway obstruction, and pulmonary edema. The key is to stabilize the patient as much as possible before doing stressful procedures, unless these procedures are life-saving measures. Upon presentation, the patient should be taken directly to the treatment area and placed in an oxygen cage. If it is 'apparent that heart failure and pulmonary
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edema are responsible for the difficult breathing, the veterinarian will manage the patient with diuretics, oxygen, and other agents to support the heart, without the benefit of radiographs. If radiographs are necessary to determine the course of the therapy to stabilize the animal, the technician should premeasure the animal and set up the machine while the animal is in oxygen; an oxygen source should accompany the animal to radiology, with endotracheal tubes and laryngoscope ready for immediate usage, if required. The causes of labored breathing are so varied that one procedure cannot be given to encompass every situation. Possible diagnostic and therapeutic measures include oxygen therapy, electrocardiogram (ECG), ventilation, chest radiographs, chest tap, blood samples, tracheal wash, echocardiography, chest tubes, and appropriate medications.lt is vital that adequate monitoring parameters be established. The basics include mucous membrane color, capillary refill time (CRT), lung auscultation, pulse rate and intensity, and respiratory rate and effort. Radiographs should be taken after air or fluid has been removed from the pleural space. Blood gas measurement can help guide the staff as to the need for oxygen or ventilatory therapy (see Hendricks). Overzealous fluid therapy can be fatal to a patient with respiratory compromise, making central venous pressure (CVP) measurement a beneficial aid in anticipating pulmonary edema. Cardiovascular System Shock is frequently caused by hemorrhage, ongoing fluid loss (such as vomiting or diarrhea), cardiac abnormalities, and/or vasodilatory substances produced in the body. Rapid fluid loss can occur with trauma, acute vomiting, burns, and acute diarrhea, lowering the blood volume and impairing circulation. The early stage of shock, the compensatory stage, results in constrietion of blood vessels, elevation of heart rate, and an increase in the strength of contraction of the heart muscle. The amount of fluid in the circulation is now sufficient so that the Hood pre~sure is increased, and blood delivery to the heart and brain, the two most vital organs, is preserved. Therapy to rapidly replace fluids lo~t during this stage generally leads to favorable results if the cause of the loss is eliminated. · With further volume loss, the blood vessels to the muscles, skin, and abdominal organs tightly constrict. This can lead to problems of low oxygen delivery to these tissues, clotting abnormalities, increased capillary permeability, and toxic circulating substances. This middle stage of shock carries a worse prognosis, unless immediate and aggressive fluid therapy is initiated. Clinical signs suggestive of this phase include tachycardia, cold extremities, hypothermia, prolonged CRT, low arterial pressure, and weak pulses. Urine output may cease once the arterial pressure is below 80 mm Hg. If the shock process progresses, the brain and heart begin to decompensate. Reduced coronary blood flow leads to myocardial failure and reduced blood flow to the brain. The blood vessels now dilate instead of constrict, causing blood to pool. This decompensatory stage has clinical signs, which include coma, heart failure, pulmonary edema, severe hypotension, and abnormal respiratory patterns. Cardiopulmonary arrest is a common sequela. Aggressive therapy with oxygen, fluids, and, possibly, drugs to support the cardiovascular system are required, but this stage is frequently irreversible. Urinary System Blood pressures less than 80 mm Hg are associated with inade quate urine production that, when prolonged, can lead to renal failure. Volume
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replacement should be started quickly, with monitoring of respiratory and cardiovascular systems for signs of fluid overload. Once the patient is "volumereplaced," urine output measurements are recorded on a per hour basis. Should the patient produce less than 1 to 2 ml/kg/hr of urine, medical decisions as to fluid challenges or diuretics must be made by the clinician (see Kirby). When urine quantities are above this amount, evaluation must be made to rule out potential overhydration versus polyuric renal disease. Ruptures may occur anywhere along the urinary tract as a result of trauma or stones. Often the first sign of rupture is free fluid in the abdomen, but this may not occur for 12 to 72 hours after trauma. To determine whether this fluid is urine, a sample of the fluid is submitted for creatinine and potassium content compared with serum values. If the fluid is urine, the values are substantially higher than in serum. Nervous System The brain contains the central controls for respiration and cardiovascular function. Problems resulting in brain hemorrhage and/or edema can have catastrophic effects. If the patient suddenly becomes stuporous or comatose, immediate reevaluation is necessary, and therapeutics to lower intracranial pressure should be initiated (see Dayrell-Hart and Klide). The integrity of the spinal cord and peripheral and cranial nerves is evaluated in the traumatized animal. Care must be taken to avoid manipulation of the spinal column until fractures or luxations have been ruled out. Atlantoaxial abnormalities can cause ascending swelling of the brainstem and can affect the cardiovascular and respiratory centers.
HISTORY Once the patient is triaged and catastrophic or life-threatening problems have stabilized, the history is recorded. A concise format is necessary, allowing the information to be scanned for·significant data. Often the nurse/technician obtains the information while the patient is being stabilized. Presenting Complaint This can be obtained from the receptionist from information that the owner has given upon registering. This information should be listed at the top of the chart so that the veterinarian can use it to help prioritize cases that are waiting. It is generally better not to begin history questioning with this inquiry, since it frequently leads the client to endless discussion. Last Normal Ask when the animal was last completely normal. If it is a geriatric patient, "normal" may be different from what normal is for a younger animal. The presenting problem may have just begun, but the animal may have been showing subtle signs of illness, such as anorexia or listlessness, for a longer period of time. Progression A chronology of the progression is recorded. The veterinarian should be able to scan this section and get a day-by-day idea of what the animal has been doing that is abnormal since the onset of signs. When problems are mentioned, such as vomiting or diarrhea, they should be characterized (e.g., color, consis-
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tency, relationship to eating, ability to ingest and retain fluids or solids, frequency, and so forth). Systems Review Other organ systems not involved in the progression are investigated. Urination, water intake, vomiting, diarrhea, coughing, sneezing, lameness, loss of consciousness, trauma, discharges, and possible intoxications should be assessed. When the owner reports an abnormality, further questioning can better define the problem. Background Information Past medical problems that required veterinary care, medications, drug and food sensitivities, blood transfusions, and date of last vaccinations should be recorded.
PHYSICAL EXAMINATION The physical evaluation initially concentrates on the four critical organ systems. Temperature, pulse rate and intensity, and respiratory rate and effort (TPR) provide vital information and are obtained immediately upon presentation. Quick assessment of level of consciousness, mucous membrane color, urinary bladder size, and CRT is made and recorded. This is often the extent of the physical examination until the patient's most life-threatening problem is treated. Working from head to tail, particular attention is given to heart and lung auscultation for abnormalities and to abdominal, rectal, and joint palpation for pain or enlargements. Acute abdominal pain requires localization and auscultation to rule out problems within the reticuloendothelial, reproductive, urinary, or gastrointestinal systems, the peritoneal space, or the muscle, skin, nerves, or fat around the abdominal wall. Fever of unknown origin directs examination to the peritoneal space and to the reproductive, urinary, and cardiovascular systemi. If the history guides the examiner to one particular organ system, care should be taken to avoid a narrow focus to the exclusion of other organ systems ("tunnel vision").
DATABASE An initial critical patient data base should consist of measurements of packed cell volume (PCV), total solids (TS), glucose, blood urea nitrogen (BUN), sodium, potassium, and urinalysis before fluid administration. The PCV and TS tests aid in assessing dehydration, red cell content, and serum protein content. Icteric, hemolyzed, or lipemic serum mandates further testing for diseases such as hemolytic anemia, pancreatitis, or liver disease. High BUN values imply prerenal, postrenal, or renal compromise. Low values warrant examination for liver disease. Hypoglycemia should be corrected and causes of hyperglycemia and hypoglycemia investigated. The specific gravity of urine prior to fluid treatment provides an indication of the concentrating capacity of the kidneys. A urine dipstick can be used to determine levels of urine glucose, ketones, blood, protein, urobilinogen, and pH. The sediment is evaluated for the presence of casts, white blood cells, bacteria, and crystals.
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Bleeding disorders are suspected when excessive bleeding is noted from venipuncture or catheter sites, when petechiation or bruising is noted on the animal's skin, or when history or physical findings suggest such a disorder. Blood smears to estimate platelet number, buccal bleeding time to evaluate platelet number and function, and activated clotting times to test the intrinsic clotting cascade should be done in the emergency room. More sophisticated testing procedures are described elsewhere in this issue (see Wingfield and VanPelt).
WRITTEN ORDERS Written hospital orders should list six areas of patient management: These are fluid orders, medication orders, diagnostic plan, monitoring procedures, nursing orders, potential equipment needs, and criteria for clinician notification.
Fluid Orders Specific instructions for fluid choice, rate, and route of administration are given. These should be reviewed by the clinician at least every 8 hours and revisions made as indicated. Intravenous or intraosseous routes should be used for the critical patient. When perfusion is poor, administration of fluids or drugs by central vein provides more rapid uptake than via peripheral vein. Microdrip infusion sets (deliver 60 drops/ml) should be used for any patient under 5 kg body weight and for cats. These infusion sets are also suited for constant rate of infusion of medications. When exact volume administration is crucial, the use of an infusion pump is indicated. This equipment reliably delivers a prescribed volume of fluid on a per hour basis and signals the staff' when the line is occluded, the fluid bottle is empty, or the equipment is malfunctioning.
Medication Orders Medications to be administered must be prescribed, indicating dosage, route, rate, and frequency of administration. If side effects are possible, means of recognizing and counteracting them are listed.
Diagnostic Plan The technician performs the majority of the diagnostic procedures. These should be requested in order of priority in the hospital orders. Precautions to be taken during the testing are indicated (e.g., "Keep the patient on oxygen during radiographic procedures").
Monitoring Procedures Database information can be used as a monitoring tool. Serial samples are requested; the trend of change is more significant than the actual value. Other monitoring tools include central venous pressure measurement, blood pressure, ECG, ventilometry, and cardiac output measurements (see Haskins).
Nursing Orders and Potential Equipment Needs Recumbent patients should be turned every 2 to 4 hours to prevent hypostatic congestion. When it is likely that the patient will vomit, the head is placed in a lowered position and directions for gastric or esophageal suctioning provided. If intracranial pressure elevation is a concern, the head is elevated. Unconscious patients should be intubated if respiratory difficulties are antici-
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pated, and instructions for hyperoxygenation prior to tracheal suctioning should be written. Ophthalmic lubricant is placed in the eyes. Criteria for initiation or cessation of warming or cooling procedures are outlined. Special instructions are required for postoperative or traumatized patients, with regard to wound care or chest tube management. Aseptic technique is always used during invasive procedures. Hands are carefully washed between patients and contaminated equipment or clothing removed or cleaned. When an animal's natural immunity is compromised, special instructions regarding additional aseptic techniques are often provided. If a species-specific contagious disease is suspected (e.g., parvovirus, distemper), precautions to eliminate contamination and spread of disease must be included in the orders. Any suspicion of a zoonotic disease should be clearly stated on the patient cage and record. The number of personnel handling the patient is kept to a minimum and protective clothing, gloves, and/or mask used as necessary. Used disposables and bodily fluids and excretions are discarded in accordance with health department regulations, in biohazard containers. When zoonotic disease is definitively diagnosed, each staff member exposed to the animal should be notified and directed to consult a physician. Certain diseases require that the state health department be notified. When major complications are anticipated, preparations should be made ahead of time for rapid intervention. Potential equipment needs should be listed in the orders. These needs might include a cut-down set, tracheostomy tube, ventilator, or tracheal tubes and oxygen source.
Criteria for Clinician Notification Because the clinician cannot be continuousJy present to reevaluate the patient, guidelines must be set, instructing the nursing staff to notify the doctor under specific circumstances. There are some situations in which the clinician does not need to be directly notified of changes but can instead provide guidelines for intervention when anticipated changes occur. An example: If the PCV falls below 10 per cent, begin a 150-ml transfusion, using packed cells from d.onor # _ _ .·
Laboratory and monitoring data is best evaluated when kept in a flow chart (Fig. 2); this allows easy comparison and contrast. Each time the patient is monitored, treated, or evaluated, a summary of what was done, observed, or decided should be written under "Progress Notes" and signed, noting date and time. When the clinicians and nurses change shifts, rounds should be conducted with parameters and specific concerns communicated regarding each patient.
DAILY ICU CONCERNS Once catastrophic and life-threatening problems have been stabilized, daily critical care is required until recovery. The problems list is updated daily, with new problems added, resolved problems deleted, and problems prioritized by severity. Through understanding the pathophysiology of the disease processes, complications are anticipated. Monitoring procedures are employed for early detection of dysfunctions, giving optimal chance for successful therapeutic intervention. Results obtained from monitoring should be reviewed at least every 8 hours and hospital orders revised accordingly.
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Time TPR
REBECCA KIRBY
Time PCV TS DEX AZO
Time Fluids: Type & Volume
Food Intake Time Type & Amount
Time Urine Output Vomitus BM
Blood Pressure Direct !rime Doppler Time Systolic Mean Systolic Diastolic
[ime CVP
Chest Tube Aspirate Right Time Left Air Fluid Air Fluid
Figure 2. Critical care data How charts. These charts provide a means for recording and comparing monitoring parameters. (Created by Nancy Shaffran, Head ICU nurse, Veterinary Hospital of the University of Pennsylvania, Philadelphia, PA; with permission.)
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Attention must be given to the individual needs of the patient. Invasive procedures should be kept to a minimum and pain controlled (see Bednarski) whenever the underlying condition allows. When possible, lighting should be dimmed and noise kept to a minimum during the night to provide the animal with a diurnal rhythm and, when possible, uninterrupted sleep. Tender, loving care, to include petting and talking to the animals, is crucial to promoting good patient mental attitude. Owner visitations should be encouraged when found to benefit the patient. Recently, critical care specialists and nutritionists have begun to research and employ nutritional techniques in the critical patient. Energy through fat and glucose calories as well as amino acid and vitamin requirements can be calculated and provided by either parenteral route (see .Remillard and Thatcher) or enteral route (see Special Article by Armstrong, Hand, and Frederick in next Clinics issue). Requirements vary with the species and disease processes involved. Not only must the underlying disease be diagnosed, monitored, and managed, but extreme care must be taken to prevent the patient from getting infections from the environment, termed nosocomial infections (see Murtaugh and Mason). Utilization of sterile materials, sterile or disinfected equipment, aseptic techniques for catheter placement, minimally invasive diagnostic and therapeutic procedures, adequate personnel hygiene between patients, frequent disinfection of the environment, and selective antibiotic usage are each vital to avoid nosocomial complications.
SPECIAL CONSIDERATIONS FOR THE CAT Cats present a special challenge. Many cats do not show clinical abnormalities until the disease is advanced. Their small body size, poor tolerance for stress, and drug sensitivities require constant monitoring for complications. Points of special concern i,n the criti-cally ill cat are presented in Table 3.
Table 3.
Parameters That Are Difficult to Managein the Critical Cat
Poor tolerance of stress and restraint-Must often use sedation or avoid invasive procedures because of struggling Catheter placement Long-term catheterization-Best in medial femoral vein or intraosseous route Smaller blood volume 50-55 ml/kg-Restricts volume of blood taken for laboratory testing Use microdrip, cannister infusion sets or infusion pumps to prevent too-rapid fluid administration Temperature regulation Hypothermia-Can result from endogenous toxins, exogenous toxins, poor perfusion, small size, and less fat allowing excessive heat loss Can result in slower metabolism, shivering, and increased energy usage during warming Decreased anesthetic needs Difficult to safely warm Hyperthermia-Can re·sult from release of pyrogens, heat exposure Can result in increased metabolic rate with dehydration, arrhythmias, hypoxia, azotemia, high energy needs, hypoglycemia, or DIC Difficult to pharmacologically cool because aspirin and acetaminophen toxic to cats (Table continued on following page)
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Table 3.
(Continued).
Potassium regulation Hypokalemia-Can result from renal wasting, anorexia, catabolism Can result in severe weakness or myopathy Hyperkalemia-Can result from oliguria/anuria, muscle damage Can result in lethal cardiac arrhythmias Glucose regulation Hyperglycemia-Can be stress-induced; diabetes mellitus can be transient Hypoglycemia-Can be due to anorexia, insulin sensitive Can cause severe cerebral depression or seizures and decreased metabolism Cardiac disorders Cardiomyopathies-Different forms managed by significantly different methods Thrombosis and emboli frequent complications Arrhythmias-Identification and treatment of underlying causes such as hypoxia, potassium or calcium imbalances, heart disease, digoxin toxicity; acidemia, poor ventilation, or volume depletion is more common Drug metabolism differs Lack of glucuronide transferase Drug dosages or interval changes required Aspirin-10 mg/kg q 52 h PO Digoxin-0.0055 mg/kg q 12-24 h PO Furosemide-2.5 mg/kg/day divided q 6-8 h Lidocaine-0.25-0.5 mg/kg IV Eating habits Special diets (e.g., low protein) will not be eaten Anorexia leads to hepatic lipidosis Different nutritional requirements* Amino acid requirements-6 g protein/lOG kcal of total Energy requirement Cannot synthesize all essential amino acid Taurine supplementation required after' 1 week nutritional support Feline viral diseases Significant immunosuppression-FeLV, FIV Other viruses-FIP, distemper, upper respiratory viruses Failure to show typical signs of diseases Vomiting not typical with feline pancreatitis Respiratory pattern and rate changes not grossly evident until massive compromise Water intake and urine output difficult to subjectively quantify *See Remillard and Thatcher, elsewhere in this issue. DIC = disseminated intravascular coagulation; FeLV = feline leukemia virus; FIV = feline immunodeficiency virus; FIP =feline infectious peritonitis
SUMMARY
Important keys to successful patient management include:
1. Identify and treat the most life-threatening problems first. 2. Make the patient as stable as possible before undertaking stressful procedures. 3. The critical patient's condition is rapidly changing and requires intensive monitoring and frequent reevaluation. 4. It is important to anticipate complications and initiate monitoring procedures for early detection.
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5. The trend of changes in monitored parameters is more significant than a single value. 6. Make sure that the treatment orders are clear and concise and that the technical staff and clinicians have the same interpretations of monitoring values and treatment regimens. 7. Many post-trauma complications do not become evident for 24 to 72 hours. 8. Do not take a patient's stable condition for granted. 9. There is less tolerance for error, indecisiveness, or delay in the critical patient. Section of Medicine, Room 2051 School ofVeterinary Medicine University of Pennsylvania 3850 Spruce Street Philadelphia, PA 19104-6010
0195-5616/89 $0.00 + .20
Critical Care-The Overview Rebecca Kirby, DVM*
Critical care is the stabilization, diagnosis, monitoring, and definitive therapy of the patient with catastrophic or life-threatening problems. Presentation can be as an emergency patient with an acute illness, as a chronically ill patient that has decompensated, or as a hospitalized patient that has developed unexpected serious complications. All postoperative patients are considered critical care patients until life-threatening anesthetic or surgical complications are ruled out. Catastrophic problems (airway obstruction, respiratory failure, and circulatory failure) lead to death within seconds if left untreated. Life-threatening complications allow more time for stabilization and usually involve one or more of the following four organ systems: cardiovascular, respiratory, urinary, and nervous systems. The acutely ill patient presents a special challenge because the underlying diagnosis may not be known during the first 24 to 48 hours of hospitalization, when critical decisions must be made. The diagnostic, monitoring, and therapeutic procedures must be coordinated with a coherent, prioritized approach as the patient moves from the emergency 'situation to surgery or diagnostic procedures and then finally to the critical care area. This requires a problem-oriented approach, with a "temporary problems" list compiled upon admission from the history, physical findings, and minimum database. Diagnostic, therapeutic, and monitoring plans are eutlined for each problem (Fig. 1). The hospital orders are derived from this outline. The patient's most life-threatening problem is listed first and managed before proceeding with less necessary diagnostic and therapeutic procedures. The problems list and prioritization are revised as changes occur in the patient's condition. Variables that contribute to the overall success of patient resuscitation are listed in Table 1. Therapeutic failures do not generally result from ignorance but rather from failure to act expeditiously at a crucial moment. Therapy must be provided at the right time, in the right amount, and in the right order.
*Diplomate, American College of Veterinary Internal Medicine; Charter Diplomate, American College ofVeterinary Emergency and Critical Care; Director, Emergency Services, Veterinary Hospital, and Assistant Professor, Emergency Medicine, University of Pennsylvania School ofVeterinary Medicine, Philadelphia, Pennsylvania Veterinary Clinics of North America: Small Animal Practice-Val. 19, No.6, November 1989
1007
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REBECCA KIRBY
Emergency Service Initial Treatment Sheet Temporary Problem List Diagnostic Plan Therapeutic Plan Monitoring Procedures
Figure l. Temporary problems list format. ProW ems are listed in order of priority, with the most life-threatening problem listed first. Diagnostic, therapeutic, and monitoring plans are listed for each problem.
TRIAGE Triage is the art of prioritizing the patients and their problems upon presentation to the hospital. This initial assessment determines waiting time for the emergency patient before complete examination and therapeutic intervention. During triage, a brief summary of the owner's primary complaint and the time of onset are obtained. The animal is removed from the carrier or towel and quickly examined for abnormalities listed in Table 2. Significant changes from normal require that the patient be taken directly to the treatment area.
Table 1.
Factors Affecting Successful Patient Resuscitation
Primary illness or injury Amount of fluid or blood lost Patient age and previous health Number and extent of associate9 medical conditions Time delay in instituting therapy Volume and rate of fluid administration Choice of fluids: crystalloid, blood components, or synthetic colloids
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Table 2.
Physical Parameters Assessed During Triage
Active hemorrhage Labored or questionable breathing patterns Rapid shallow breathing-Suspect pleural space disease Loud breathing-Suspect upper airway disease Labored inspiration/expiration-Suspect lung parenchymal disease Prolonged forced expiration-Suspect small airway disease Mucous membrane color-Color other than pink is abnormal Capillary refill time (CRT)-Greater than 2 seconds or less than A to 1 second is abnormal Pulse rate Dogs-Less than 60 and greater than 200 beats per minute are abnormal Cats-Less than 150 and greater than 250 beats per minute are abnormal Fractures-Open or unstable and likely to cause soft tissue damage Altered mentation-Seizures, uncontrolled hyperexcitability, stupor, coma Open wounds
In addition to the presence of abnormal physical parameters, there are several historical or observed problems that warrant immediate triage to the treatment area. These include: Trauma Profuse diarrhea Urethral obstruction Labored breathing Seizures Loss of consciousness Excessive bleeding History of poisoning Prolapsed organs Potential snakebite
Heat prostration Open wounds exposing extensive soft tissue or bone Shock Anemia Burns Dystocias Expired animals (for the client's benefit)
Rapid physical assessment of patient stability and prioritization of problem.s are also performed each time a critical patient is monitored within the intensive care unit (ICU). Specific problems such as profuse diarrhea, urethral obstruction, labored breathing, excessive bleeding, hyperthermia, or loss of consciousness alert the clinician or nurse that life-threatening complications are imminent. These animals are then "triaged" as high-priority patients within the ICU, and therapeutic and monitoring efforts are intensified.
MANAGEMENT OF CATASTROPHIC PROBLEMS Airway patency, oxygenation, ventilation, and tissue perfusion are the main areas of concern during triage. Airway obstruction, apnea or ineffective breathing, and circulatory failure lead to catastrophic problems, with all tissues compromised; multiple organ failure results, with death the final complication. Assessment and management of airway, breathing, and circulation in critical patients are similar, regardless of the underlying diagnosis. Airway patency is first assessed and steps taken to clear obstructions through intubation or tracheostomy (see Paddleford and Harvey). Oxygen and ventilatory support are provided (see Hendricks). When the heartbeat is absent, immedi-
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ate cardiopulmonary cerebral resuscitation is initiated (see Robello and Crowe). The presence of a heartbeat with circulatory failure warrants examination of cardiac function and rhythm as well as blood pressure (see Fox). Hypovolemic or hemorrhagic shock requires aggressive fluid and/or blood component therapy. Blood pressure support may be indicated, once intravascular fluid volume has been replaced. Cardiogenic shock requires reduction of cardiac preload and afterload. Myocardial contractility is supported or pericardia! effusion drained, as necessary. Septic shock is managed through intravascular volume support, drainage of septic foci, and administration of appropriate antibiotics (see Goodwin and Schaer). Reperfusion injury causes tissue and cellular damage through the production of oxygen free radicals and increased intracellular calcium, sodium, and water (see Muir). Fluid, electrolyte, and acid-base imbalances result, requiring assessment and stabilization (see Garvey). All tissues of the body are affected by ischemia-reperfusion, with the kidneys severely affected. Renal function must be aggressively monitored and therapeutics employed at the first sign of compromise (see Kirby). Capillary stasis and tissue hypoxia predispose to sludging of blood, increased capillary permeability, and platelet aggregation. Intravascular consumption of clotting factors can result in significant bleeding (see Wingfield and VanPelt) Intensive monitoring techniques are employed to detect early signs of decompensation (see Haskins), with concentrated efforts given to the four critical organ systems, abnormal bleeding, and sepsis. The pivotal point of therapy during resuscitation is protection of brain function. The status of brain function will determine the quality of life subsequent to recovery. Repeated 'neurologic examinations and therapeutics to · reduce intracranial pressure are vital to long-term patient survival (see Dayrell-Hart and Klide).
LIFE-THREATENING PROBLEMS Life-threatening problems allow more time for resuscitation but progress to catastrophic problems if left untreated. Many are identified through triage, whereas others are suspected from historical, physical, or database findings. Most life-threatening problems involve one or more of the following four organ systems: respiratory, cardiovascular, neurologic, and urinary systems. Respiratory System Abnormal breathing may be due to pathology anywhere along the respiratory tract, including the nasopharyngeal region, larynx, trachea, bronchi, bronchioles, and lung tissue. Trauma is a major cause of abnormal breathing, resulting in pneumothorax, pulmonary contusions, fractured ribs, ruptured bullae or airways, and/or pleural hemorrhage. It must be recognized that breathing problems may not be evident for 12 to 72 hours post-trauma. Other causes of labored breathing include fluid accumulation within the pleural space, asthma, mass lesions, pneumonia, airway obstruction, and pulmonary edema. The key is to stabilize the patient as much as possible before doing stressful procedures, unless these procedures are life-saving measures. Upon presentation, the patient should be taken directly to the treatment area and placed in an oxygen cage. If it is 'apparent that heart failure and pulmonary
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edema are responsible for the difficult breathing, the veterinarian will manage the patient with diuretics, oxygen, and other agents to support the heart, without the benefit of radiographs. If radiographs are necessary to determine the course of the therapy to stabilize the animal, the technician should premeasure the animal and set up the machine while the animal is in oxygen; an oxygen source should accompany the animal to radiology, with endotracheal tubes and laryngoscope ready for immediate usage, if required. The causes of labored breathing are so varied that one procedure cannot be given to encompass every situation. Possible diagnostic and therapeutic measures include oxygen therapy, electrocardiogram (ECG), ventilation, chest radiographs, chest tap, blood samples, tracheal wash, echocardiography, chest tubes, and appropriate medications.lt is vital that adequate monitoring parameters be established. The basics include mucous membrane color, capillary refill time (CRT), lung auscultation, pulse rate and intensity, and respiratory rate and effort. Radiographs should be taken after air or fluid has been removed from the pleural space. Blood gas measurement can help guide the staff as to the need for oxygen or ventilatory therapy (see Hendricks). Overzealous fluid therapy can be fatal to a patient with respiratory compromise, making central venous pressure (CVP) measurement a beneficial aid in anticipating pulmonary edema. Cardiovascular System Shock is frequently caused by hemorrhage, ongoing fluid loss (such as vomiting or diarrhea), cardiac abnormalities, and/or vasodilatory substances produced in the body. Rapid fluid loss can occur with trauma, acute vomiting, burns, and acute diarrhea, lowering the blood volume and impairing circulation. The early stage of shock, the compensatory stage, results in constrietion of blood vessels, elevation of heart rate, and an increase in the strength of contraction of the heart muscle. The amount of fluid in the circulation is now sufficient so that the Hood pre~sure is increased, and blood delivery to the heart and brain, the two most vital organs, is preserved. Therapy to rapidly replace fluids lo~t during this stage generally leads to favorable results if the cause of the loss is eliminated. · With further volume loss, the blood vessels to the muscles, skin, and abdominal organs tightly constrict. This can lead to problems of low oxygen delivery to these tissues, clotting abnormalities, increased capillary permeability, and toxic circulating substances. This middle stage of shock carries a worse prognosis, unless immediate and aggressive fluid therapy is initiated. Clinical signs suggestive of this phase include tachycardia, cold extremities, hypothermia, prolonged CRT, low arterial pressure, and weak pulses. Urine output may cease once the arterial pressure is below 80 mm Hg. If the shock process progresses, the brain and heart begin to decompensate. Reduced coronary blood flow leads to myocardial failure and reduced blood flow to the brain. The blood vessels now dilate instead of constrict, causing blood to pool. This decompensatory stage has clinical signs, which include coma, heart failure, pulmonary edema, severe hypotension, and abnormal respiratory patterns. Cardiopulmonary arrest is a common sequela. Aggressive therapy with oxygen, fluids, and, possibly, drugs to support the cardiovascular system are required, but this stage is frequently irreversible. Urinary System Blood pressures less than 80 mm Hg are associated with inade quate urine production that, when prolonged, can lead to renal failure. Volume
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replacement should be started quickly, with monitoring of respiratory and cardiovascular systems for signs of fluid overload. Once the patient is "volumereplaced," urine output measurements are recorded on a per hour basis. Should the patient produce less than 1 to 2 ml/kg/hr of urine, medical decisions as to fluid challenges or diuretics must be made by the clinician (see Kirby). When urine quantities are above this amount, evaluation must be made to rule out potential overhydration versus polyuric renal disease. Ruptures may occur anywhere along the urinary tract as a result of trauma or stones. Often the first sign of rupture is free fluid in the abdomen, but this may not occur for 12 to 72 hours after trauma. To determine whether this fluid is urine, a sample of the fluid is submitted for creatinine and potassium content compared with serum values. If the fluid is urine, the values are substantially higher than in serum. Nervous System The brain contains the central controls for respiration and cardiovascular function. Problems resulting in brain hemorrhage and/or edema can have catastrophic effects. If the patient suddenly becomes stuporous or comatose, immediate reevaluation is necessary, and therapeutics to lower intracranial pressure should be initiated (see Dayrell-Hart and Klide). The integrity of the spinal cord and peripheral and cranial nerves is evaluated in the traumatized animal. Care must be taken to avoid manipulation of the spinal column until fractures or luxations have been ruled out. Atlantoaxial abnormalities can cause ascending swelling of the brainstem and can affect the cardiovascular and respiratory centers.
HISTORY Once the patient is triaged and catastrophic or life-threatening problems have stabilized, the history is recorded. A concise format is necessary, allowing the information to be scanned for·significant data. Often the nurse/technician obtains the information while the patient is being stabilized. Presenting Complaint This can be obtained from the receptionist from information that the owner has given upon registering. This information should be listed at the top of the chart so that the veterinarian can use it to help prioritize cases that are waiting. It is generally better not to begin history questioning with this inquiry, since it frequently leads the client to endless discussion. Last Normal Ask when the animal was last completely normal. If it is a geriatric patient, "normal" may be different from what normal is for a younger animal. The presenting problem may have just begun, but the animal may have been showing subtle signs of illness, such as anorexia or listlessness, for a longer period of time. Progression A chronology of the progression is recorded. The veterinarian should be able to scan this section and get a day-by-day idea of what the animal has been doing that is abnormal since the onset of signs. When problems are mentioned, such as vomiting or diarrhea, they should be characterized (e.g., color, consis-
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tency, relationship to eating, ability to ingest and retain fluids or solids, frequency, and so forth). Systems Review Other organ systems not involved in the progression are investigated. Urination, water intake, vomiting, diarrhea, coughing, sneezing, lameness, loss of consciousness, trauma, discharges, and possible intoxications should be assessed. When the owner reports an abnormality, further questioning can better define the problem. Background Information Past medical problems that required veterinary care, medications, drug and food sensitivities, blood transfusions, and date of last vaccinations should be recorded.
PHYSICAL EXAMINATION The physical evaluation initially concentrates on the four critical organ systems. Temperature, pulse rate and intensity, and respiratory rate and effort (TPR) provide vital information and are obtained immediately upon presentation. Quick assessment of level of consciousness, mucous membrane color, urinary bladder size, and CRT is made and recorded. This is often the extent of the physical examination until the patient's most life-threatening problem is treated. Working from head to tail, particular attention is given to heart and lung auscultation for abnormalities and to abdominal, rectal, and joint palpation for pain or enlargements. Acute abdominal pain requires localization and auscultation to rule out problems within the reticuloendothelial, reproductive, urinary, or gastrointestinal systems, the peritoneal space, or the muscle, skin, nerves, or fat around the abdominal wall. Fever of unknown origin directs examination to the peritoneal space and to the reproductive, urinary, and cardiovascular systemi. If the history guides the examiner to one particular organ system, care should be taken to avoid a narrow focus to the exclusion of other organ systems ("tunnel vision").
DATABASE An initial critical patient data base should consist of measurements of packed cell volume (PCV), total solids (TS), glucose, blood urea nitrogen (BUN), sodium, potassium, and urinalysis before fluid administration. The PCV and TS tests aid in assessing dehydration, red cell content, and serum protein content. Icteric, hemolyzed, or lipemic serum mandates further testing for diseases such as hemolytic anemia, pancreatitis, or liver disease. High BUN values imply prerenal, postrenal, or renal compromise. Low values warrant examination for liver disease. Hypoglycemia should be corrected and causes of hyperglycemia and hypoglycemia investigated. The specific gravity of urine prior to fluid treatment provides an indication of the concentrating capacity of the kidneys. A urine dipstick can be used to determine levels of urine glucose, ketones, blood, protein, urobilinogen, and pH. The sediment is evaluated for the presence of casts, white blood cells, bacteria, and crystals.
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Bleeding disorders are suspected when excessive bleeding is noted from venipuncture or catheter sites, when petechiation or bruising is noted on the animal's skin, or when history or physical findings suggest such a disorder. Blood smears to estimate platelet number, buccal bleeding time to evaluate platelet number and function, and activated clotting times to test the intrinsic clotting cascade should be done in the emergency room. More sophisticated testing procedures are described elsewhere in this issue (see Wingfield and VanPelt).
WRITTEN ORDERS Written hospital orders should list six areas of patient management: These are fluid orders, medication orders, diagnostic plan, monitoring procedures, nursing orders, potential equipment needs, and criteria for clinician notification.
Fluid Orders Specific instructions for fluid choice, rate, and route of administration are given. These should be reviewed by the clinician at least every 8 hours and revisions made as indicated. Intravenous or intraosseous routes should be used for the critical patient. When perfusion is poor, administration of fluids or drugs by central vein provides more rapid uptake than via peripheral vein. Microdrip infusion sets (deliver 60 drops/ml) should be used for any patient under 5 kg body weight and for cats. These infusion sets are also suited for constant rate of infusion of medications. When exact volume administration is crucial, the use of an infusion pump is indicated. This equipment reliably delivers a prescribed volume of fluid on a per hour basis and signals the staff' when the line is occluded, the fluid bottle is empty, or the equipment is malfunctioning.
Medication Orders Medications to be administered must be prescribed, indicating dosage, route, rate, and frequency of administration. If side effects are possible, means of recognizing and counteracting them are listed.
Diagnostic Plan The technician performs the majority of the diagnostic procedures. These should be requested in order of priority in the hospital orders. Precautions to be taken during the testing are indicated (e.g., "Keep the patient on oxygen during radiographic procedures").
Monitoring Procedures Database information can be used as a monitoring tool. Serial samples are requested; the trend of change is more significant than the actual value. Other monitoring tools include central venous pressure measurement, blood pressure, ECG, ventilometry, and cardiac output measurements (see Haskins).
Nursing Orders and Potential Equipment Needs Recumbent patients should be turned every 2 to 4 hours to prevent hypostatic congestion. When it is likely that the patient will vomit, the head is placed in a lowered position and directions for gastric or esophageal suctioning provided. If intracranial pressure elevation is a concern, the head is elevated. Unconscious patients should be intubated if respiratory difficulties are antici-
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pated, and instructions for hyperoxygenation prior to tracheal suctioning should be written. Ophthalmic lubricant is placed in the eyes. Criteria for initiation or cessation of warming or cooling procedures are outlined. Special instructions are required for postoperative or traumatized patients, with regard to wound care or chest tube management. Aseptic technique is always used during invasive procedures. Hands are carefully washed between patients and contaminated equipment or clothing removed or cleaned. When an animal's natural immunity is compromised, special instructions regarding additional aseptic techniques are often provided. If a species-specific contagious disease is suspected (e.g., parvovirus, distemper), precautions to eliminate contamination and spread of disease must be included in the orders. Any suspicion of a zoonotic disease should be clearly stated on the patient cage and record. The number of personnel handling the patient is kept to a minimum and protective clothing, gloves, and/or mask used as necessary. Used disposables and bodily fluids and excretions are discarded in accordance with health department regulations, in biohazard containers. When zoonotic disease is definitively diagnosed, each staff member exposed to the animal should be notified and directed to consult a physician. Certain diseases require that the state health department be notified. When major complications are anticipated, preparations should be made ahead of time for rapid intervention. Potential equipment needs should be listed in the orders. These needs might include a cut-down set, tracheostomy tube, ventilator, or tracheal tubes and oxygen source.
Criteria for Clinician Notification Because the clinician cannot be continuousJy present to reevaluate the patient, guidelines must be set, instructing the nursing staff to notify the doctor under specific circumstances. There are some situations in which the clinician does not need to be directly notified of changes but can instead provide guidelines for intervention when anticipated changes occur. An example: If the PCV falls below 10 per cent, begin a 150-ml transfusion, using packed cells from d.onor # _ _ .·
Laboratory and monitoring data is best evaluated when kept in a flow chart (Fig. 2); this allows easy comparison and contrast. Each time the patient is monitored, treated, or evaluated, a summary of what was done, observed, or decided should be written under "Progress Notes" and signed, noting date and time. When the clinicians and nurses change shifts, rounds should be conducted with parameters and specific concerns communicated regarding each patient.
DAILY ICU CONCERNS Once catastrophic and life-threatening problems have been stabilized, daily critical care is required until recovery. The problems list is updated daily, with new problems added, resolved problems deleted, and problems prioritized by severity. Through understanding the pathophysiology of the disease processes, complications are anticipated. Monitoring procedures are employed for early detection of dysfunctions, giving optimal chance for successful therapeutic intervention. Results obtained from monitoring should be reviewed at least every 8 hours and hospital orders revised accordingly.
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Time TPR
REBECCA KIRBY
Time PCV TS DEX AZO
Time Fluids: Type & Volume
Food Intake Time Type & Amount
Time Urine Output Vomitus BM
Blood Pressure Direct !rime Doppler Time Systolic Mean Systolic Diastolic
[ime CVP
Chest Tube Aspirate Right Time Left Air Fluid Air Fluid
Figure 2. Critical care data How charts. These charts provide a means for recording and comparing monitoring parameters. (Created by Nancy Shaffran, Head ICU nurse, Veterinary Hospital of the University of Pennsylvania, Philadelphia, PA; with permission.)
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Attention must be given to the individual needs of the patient. Invasive procedures should be kept to a minimum and pain controlled (see Bednarski) whenever the underlying condition allows. When possible, lighting should be dimmed and noise kept to a minimum during the night to provide the animal with a diurnal rhythm and, when possible, uninterrupted sleep. Tender, loving care, to include petting and talking to the animals, is crucial to promoting good patient mental attitude. Owner visitations should be encouraged when found to benefit the patient. Recently, critical care specialists and nutritionists have begun to research and employ nutritional techniques in the critical patient. Energy through fat and glucose calories as well as amino acid and vitamin requirements can be calculated and provided by either parenteral route (see .Remillard and Thatcher) or enteral route (see Special Article by Armstrong, Hand, and Frederick in next Clinics issue). Requirements vary with the species and disease processes involved. Not only must the underlying disease be diagnosed, monitored, and managed, but extreme care must be taken to prevent the patient from getting infections from the environment, termed nosocomial infections (see Murtaugh and Mason). Utilization of sterile materials, sterile or disinfected equipment, aseptic techniques for catheter placement, minimally invasive diagnostic and therapeutic procedures, adequate personnel hygiene between patients, frequent disinfection of the environment, and selective antibiotic usage are each vital to avoid nosocomial complications.
SPECIAL CONSIDERATIONS FOR THE CAT Cats present a special challenge. Many cats do not show clinical abnormalities until the disease is advanced. Their small body size, poor tolerance for stress, and drug sensitivities require constant monitoring for complications. Points of special concern i,n the criti-cally ill cat are presented in Table 3.
Table 3.
Parameters That Are Difficult to Managein the Critical Cat
Poor tolerance of stress and restraint-Must often use sedation or avoid invasive procedures because of struggling Catheter placement Long-term catheterization-Best in medial femoral vein or intraosseous route Smaller blood volume 50-55 ml/kg-Restricts volume of blood taken for laboratory testing Use microdrip, cannister infusion sets or infusion pumps to prevent too-rapid fluid administration Temperature regulation Hypothermia-Can result from endogenous toxins, exogenous toxins, poor perfusion, small size, and less fat allowing excessive heat loss Can result in slower metabolism, shivering, and increased energy usage during warming Decreased anesthetic needs Difficult to safely warm Hyperthermia-Can re·sult from release of pyrogens, heat exposure Can result in increased metabolic rate with dehydration, arrhythmias, hypoxia, azotemia, high energy needs, hypoglycemia, or DIC Difficult to pharmacologically cool because aspirin and acetaminophen toxic to cats (Table continued on following page)
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Table 3.
(Continued).
Potassium regulation Hypokalemia-Can result from renal wasting, anorexia, catabolism Can result in severe weakness or myopathy Hyperkalemia-Can result from oliguria/anuria, muscle damage Can result in lethal cardiac arrhythmias Glucose regulation Hyperglycemia-Can be stress-induced; diabetes mellitus can be transient Hypoglycemia-Can be due to anorexia, insulin sensitive Can cause severe cerebral depression or seizures and decreased metabolism Cardiac disorders Cardiomyopathies-Different forms managed by significantly different methods Thrombosis and emboli frequent complications Arrhythmias-Identification and treatment of underlying causes such as hypoxia, potassium or calcium imbalances, heart disease, digoxin toxicity; acidemia, poor ventilation, or volume depletion is more common Drug metabolism differs Lack of glucuronide transferase Drug dosages or interval changes required Aspirin-10 mg/kg q 52 h PO Digoxin-0.0055 mg/kg q 12-24 h PO Furosemide-2.5 mg/kg/day divided q 6-8 h Lidocaine-0.25-0.5 mg/kg IV Eating habits Special diets (e.g., low protein) will not be eaten Anorexia leads to hepatic lipidosis Different nutritional requirements* Amino acid requirements-6 g protein/lOG kcal of total Energy requirement Cannot synthesize all essential amino acid Taurine supplementation required after' 1 week nutritional support Feline viral diseases Significant immunosuppression-FeLV, FIV Other viruses-FIP, distemper, upper respiratory viruses Failure to show typical signs of diseases Vomiting not typical with feline pancreatitis Respiratory pattern and rate changes not grossly evident until massive compromise Water intake and urine output difficult to subjectively quantify *See Remillard and Thatcher, elsewhere in this issue. DIC = disseminated intravascular coagulation; FeLV = feline leukemia virus; FIV = feline immunodeficiency virus; FIP =feline infectious peritonitis
SUMMARY
Important keys to successful patient management include:
1. Identify and treat the most life-threatening problems first. 2. Make the patient as stable as possible before undertaking stressful procedures. 3. The critical patient's condition is rapidly changing and requires intensive monitoring and frequent reevaluation. 4. It is important to anticipate complications and initiate monitoring procedures for early detection.
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5. The trend of changes in monitored parameters is more significant than a single value. 6. Make sure that the treatment orders are clear and concise and that the technical staff and clinicians have the same interpretations of monitoring values and treatment regimens. 7. Many post-trauma complications do not become evident for 24 to 72 hours. 8. Do not take a patient's stable condition for granted. 9. There is less tolerance for error, indecisiveness, or delay in the critical patient. Section of Medicine, Room 2051 School ofVeterinary Medicine University of Pennsylvania 3850 Spruce Street Philadelphia, PA 19104-6010