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Kirby's Rule of Twenty

ISSN 2398-2950


  • Checklist developed by Dr. Rebecca Kirby, one of the founding members of the American College of Veterinary Emergency and Critical Care, and founding member of the Veterinary Institute of Trauma, Emergency, and Critical Care.
  • Checklist involves monitoring multiple organ systems in the most critically ill patients.
  • Aids in the integration of disease processes, and possible interactions of drugs associated with therapy.


  • Mortality in patients who need Rule of Twenty monitoring is high, depending on the primary disease state and response to aggressive therapy.




  • Any disease process that can predispose to a state of systemic inflammation, sepsis, or severe metabolic derangements can ultimately require Rule of Twenty Monitoring.


  • Kirby's Rule of Twenty is a checklist that should be performed daily in critically ill patients Patient monitoring for critical care.
  • A checklist can be placed or written in the daily patient record, and addressed in the patient's SOAP.
  • Not all patients will require every component each and every day, but the checklist ensures no appropriate care is missed, provides the clinician a reminder to think about addressing an important function, or justifying why the specific component doesn't need to be addressed or is not appropriate or applicable for that particular patient.

1. Fluid Balance

  • Fluid balance between the intravascular and interstitial space is dependent on hydrostatic pressure, oncotic pressure, and capillary permeability. Dehydration occurs in the interstitial space; and hypovolemia occurs in the intravascular space.
  • Skin tenting, mucous membrane, tear film/sunken eyes can be used to assess for dehydration.
  • Peripheral edema, especially distal to bandage material, elbows, digits, hocks, and dorsal neck can be assessed for overhydration. Other signs include chemosis of conjunctiva, bilateral serous nasal discharge, and jugular distension.
  • Packed cell volumes (hematocrit) Hematology: packed cell volume and total proteins Blood biochemistry: total protein (solids) concentrations to indicate hemoconcentration.
  • Urine specific gravity Urinalysis: specific gravity may be higher then normal in dehydrated patients (complicated by use of diuretics or colloids, or renal disease).
  • Urine output is a valuable indicator.
  • Bedside ultrasound can be used to assess fluid volume status.
  • Radiography Radiography: thorax or ultrasonography Ultrasonography: heart provide information on, eg heart or venous distension. However, ensure patients are stable for radiography.
  • Comparison of fluid input and output useful in IV fluid therapy over several days Fluid therapy: overview. Input measured using infusion pumps/syringes Infusion: fluid pump Infusion  syringe pump. Output measured using urinary catheter, diarrhea, vomiting, fluid from drains. In low-volume patients, output will exceed input. In normal-volume patients, input will be slightly greater than output. Insensible losses are approximately 20 ml/kg/day. With volume-overload, output will more than input. Depends on normal renal physiology and body weight should be monitored.
  • Monitoring body weight at least once a day is a good way to monitor fluid balance also.
Catheter 'line' care
  • Intravenous catheters should be checked daily for pain on flushing, erythema, and warmth at the catheter site.
  • Pyrexia Pyrexia: overview may be the first sign of catheter site infection or phlebitis.
  • Catheters should be left in place as long as possible, however should be removed immediately if not required.
  • Fever may be caused by infection in one of the catheters.

2. Oncotic Pressure

  • Oncotic pressure is important to maintain intravascular volume, and prevent excess fluid extravasation.
  • Different proteins help maintain oncotic balance, but albumin is the primary source.
  • Albumin Blood biochemistry: albumin or total protein Blood biochemistry: total protein should be measured daily, along with clinical signs of hypovolemia and peripheral edema.
  • If these clinical signs develop, then treatment with artificial colloids such as Voluven or Hetastarch; or natural colloids such as plasma should be considered.

3. Glucose

  • Hypoglycemia Hypoglycemia can occur in neonates, or secondary to sepsis, insulinomas, insulin secreting tumors, xylitol toxicity, and hypoadrenocorticism.
  • Obtundation and seizures can occur with clinical hypoglycemia.
  • If hypoglycemia is present in any patient, 0.5-1.5 mL/kg of 50% glucose diluted 1:4 should be administered IV. If there is no IV access, it can be given transmucosally. After bolus administration, intravenous fluids should be supplemented with 2.5-7.5% glucose.

4. Electrolyte   

  • Electrolyte imbalances are common in critically ill patients, and can cause neurological dysfunction, cardiovascular abnormalities, and cell dysfunction.
  • A long stay catheter placed in the jugular vein or saphenous vein is useful if regular blood sampling is required.
  • Electrolytes which should be monitored include sodium , potassium, calcium, and phosphate Fluid therapy: for acid-base imbalance.
  • Venous blood gas analysis allows measurement of pH, bicarbonate, base excess and PvCO2. Blood gas is also important to monitor at least daily in critically ill patients. Many blood gas analyzers also incorporate electrolyte measurements.

5. Oxygenation and ventilation  

  • Adequate oxygen is imperative.
  • Hemoglobin concentration has direct relevance on oxygen delivery (see 11).
  • Oxygenation can be directly measured though the use of arterial blood gas analysis Arterial blood gas sampling, or indirectly measured using a pulse oximeter Anesthetic monitoring: pulse oximetry.
  • Any animal that is hypoxic Hypoxemia should have supplemental oxygen Nasal oxygen administration or if hyperventilating should have mechanical ventilation provided Anesthetic ventilators: overview, depending on the degree of hypoxemia and whether the lungs can function normally.
  • Ventilation can be monitored directly using an arterial blood gas analysis to measure the PaCO2 level.
  • Carbon dioxide can be measured by arterial blood gas, venous blood gas, or if the patient is intubated by end tidal CO2 (ETCO2) using a capnograph Anesthetic monitoring: respiratory system (capnograph)
  • Hypoventilation can result in hypercapnia Hypercapnia and respiratory acidosis Acid base imbalance and is defined as a PaCO2/PvCO2/ETCO2 >45 mmHg.
  • If PaCO2/PvCO2/ETCO2 >60 mmHg, intubation and ventilation is required.
  • Hypocapnia is defined as PaCO2/PvCO2/ETCO2 <35 mmHg, and can result in respiratory alkalosis. Respiratory alkalosis is not as much as a concern in critically ill patients, and should be addressed by treating the underlying cause.

6. Consciousness/mentation

  • Abnormal mentation can occur during shock.
  • Any animal with traumatic brain injury Head: trauma should have a modified Glasgow coma score measure Small animal coma score and monitored throughout hospitalization for improvement or deterioration in neurological function.
  • Any seizuring patient should be on constant seizure watch Seizures.
  • If a patient is recumbent with no gag reflex due to primary neurological dysfunction or secondary to drugs such as seizure medication or sedative/anesthetic agents, intubation is required to prevent aspiration pneumonia Pneumonia and maintain a patent airway for oxygenation and ventilation.

7. Blood Pressure  

  • Blood pressure is determined by cardiac ouput x systemic vascular resistance.
  • Blood pressure can be measured directly by an arterial catheter Anesthetic monitoring: blood pressure (direct pressure), or indirectly by doppler Blood pressure: Doppler ultrasound or oscillometric methods Arterial blood pressure: oscillometric. Although direct methods are more accurate, indirect methods are usually used due to being less invasive and more practical.
  • Doppler blood pressure measures systolic blood pressure and is more accurate in smaller patients.
  • Oscillometric blood pressure measures mean arterial pressure and calculates systolic and diastolic blood pressure from this.
  • Adequate cerebral and coronary perfusion is considered to require a mean arterial pressure of at least 60 mmHg, or systolic blood pressure of 90 mmHg.
  • Systolic blood pressures greater than 180 mmHg should be addressed as it can cause cerebral, renal and retinal injury.

8. Heart rate, rhythm, and contractility  

  • ECG ECG: overview is commonly used to monitor critical care patients, as it allows continuous assessment of a patient's heart rate.
  • It allows monitoring of response to treatment (eg tachycardia resolved after fluid bolus or analgesia).
  • It allows monitoring of critical patients for acute deteriorations (eg bradycardia in a patient in shock requires immediate intervention as it can quickly lead to cardiac arrest Cardiac arrest.
  • Allows assessment of arrhythmias Heart: dysrhythmia which are not uncommon in critically ill patients and can help differentiate between cardiogenic shock (in which fluid therapy is contraindicated) and other types of shock.
  • Although a 6 lead ECG is more ideal in assessing arrhythmias, a 3 lead ECG is often adequate for most critical care monitoring ECG: principles of interpretation.
  • Adhesive skin pads on the paw pads or clipped body wall are preferable or alligator clips.
  • Telemetry ECG systems are ideal for use in critical care wards.

9. Albumin

  • Albumin is important in maintaining colloid osmotic pressure, drug carrying capacity, wound healing, and has anti-inflammatory properties, however it is rarely treated.
  • Indications for treatment of hypoalbuminemia is refractory hypotension, in which case articifical colloids or plasma can be administered.

10. Coagulation      

11. Red blood cells

  • Packed cell volume (PCV) and total protein (TP) should be measured in all critically ill patients. 
  • Concurrent TP measurement can help determine the underlying cause of the anemia.
  • Blood transfusion Blood transfusion is only indicated if there is clinical signs of anemia including tachycardia, tachypnea, decreased mentation and/or hyperlactatemia.
  • Continuous ECG measurement can be helpful in monitoring for worsening anemia in critically ill patients.

12. Renal function

  • Renal function should be determined by measuring urea Blood biochemistry: urea, creatinine Blood biochemistry: creatinine phosphokinase and by performing a urinalysis.
  • If a patient is azotemic Azotemia, the cause should be identified as pre-renal, renal, or post-renal.
  • If renal dysfunction is present, urine output should be monitored via a urinary catheter, or by collecting urine in a litter tray, kidney dish or bedding. Normal urine output should be 1-2 mL/kg/hr or equivalent to the amount of fluid being administered.

13. Immune status, antibiotics, white blood cells  

  • Hematology or in-house blood smears Blood smear should be performed if this is a concern of neutropenia, which can immunocompromise a patient.
  • If neutropenia Hematology: neutrophil is present, the underlying cause should be identified and addressed,
  • Neutropenic patients should have broad spectrum antibiotics administered Therapeutics: antimicrobial drug
  • Neutropenic patients should be barrier nursed.
  • If patients are receiving antibiotics, they should be assessed daily to see if antibiotics can be deescalated.

14. Gastrointestinal motility and mucosal integrity

  • Gastric motility can be impaired in critically ill patients, resulting in gastric distension, nausea and vomiting.
  • Gastroprotection with omeprazole Omeprazole should be administered in any patient who is regurgitating or vomiting. This will also help prevent esophagitis. Gastric ulceration does not require antibiotics.

15. Drug dose and metabolism

  • It is important to consider adjusting drug doses and frequencies in patients with renal disease, hepatic dysfunction or hypoalbuminemia. This will depend on the pharmacokinetics of the drugs.

16. Nutrition  

  • Any patient who hasn't eaten for more than 3 days should receive enteral or parenteral nutrition.
  • Even patients who are eating whould have their nutritional intake monitored to ensure they are receiving their full resting energy requirement (RER). If they aren't, supplemental nutrition should be provided.
  • When commencing nutrition in patients which have been anorexic for a while, the amount of nutrition intially provided should be approximately 30% of their resting energy requirement (RER) and increased daily until 100% of RER is reached.
  • Early enteral nutrition has been proven to improve morbidity in many diseases. It can also help improve gastric mucosal integrity and motility.
  • Enteral nutrition can be provided with nasogastric feeding tubes nasoesophageal feeding tubes, esophagostomy tubes or gastrotomy tubes Enteral nutritional support  Feeding tube and mouth gag  Esophagostomy feeding tube placement  Gastrotomy  Therapeutics: nutrition.
  • Parenteral nutrition can be provided if there a central venous or long stay catheter.

17. Pain Control 

  • Pain should be monitored in all critically ill patients.
  • There are various pain scoring systems including the modified Glasgow pain scale Pain: assessment.
  • When patients are on analgesia, they should be assessed daily to see if analgesia can be deescalated.

18. Nursing care and mobilization

  • Ocular: corneal ulcers are common in critically ill patients, therefore eyes should be cleaned and checked daily for ulceration. Eye lubricant should be applied if the patient is sedated or has no palpebral reflex.
  • Oral: if a patient can’t swallow due to neurological disease or prolonged sedation, the oral cavity should be cleaned regularly with chlorhexidine Chlorhexidine.
  • Minimize noise: noise sensitive patients such as those under light sedation may benefit from cotton balls in their ears.
  • Urinary: ensure patients are taken out or monitored for urination, to prevent bladder distension or urine scalding. If urine scalding develops, use barrier cream (eg Sudocrem).
  • Fecal: barrier cream can be applied to prevent fecal scalding from diarrhea.
  • Temperature: temperature can be monitored with a rectal thermometer or a temperature probe for continuous monitoring in recumbent patients.
  • Turning: recumbent patients should be turned every 4 hours and kept on soft bedding to prevent pressure sores Skin: decubital ulcers and atelectasis of the lungs Lung: atelectasis. Respiratory patients should be kept in sternal recumbency with legs only turned from left to right. The body should be checked regularly for pressure sores.
  • Existing arthritis: arthritic cats should be walked regularly and physiotherapy performed. Consider analgesia for arthritis.
  • Peripheral edema: if peripheral edema develops, limbs should be massaged, and in severe cases analgesia considered. Turn the patient regularly.
  • Physiotherapy: should be considered in arthritis, edematous, and in tetanus cases.
  • Catheter care: IV catheters should be checked daily for phlebitis, dislodgement or purulent discharge. Other catheters and tubes should also be monitored regularly.

19. Wound care and bandage changes

  • Wounds and bandages require regular monitoring Wound: bandage.
  • If strike through is present, it is important to change the bandage immediately to prevent nosocomial infections Hospital-associated infections.
  • If a patient is bothered by their wound, there may be a problem such a worsening wound or too tight bandage.
  • If a bandage or cast is applied to the leg, the digits below should be checked for swelling, perfusion (warmth), and for pain sensation.
  • If drains are placed, these can be a source of nosocomial infection, so should be properly dressed with appropriate dressing material Wound: drainage. They should be removed as soon as they are not required. If there is fluid production of less than 1-2 mL/kg/day, they drain should be removed. Any fluid drained should be calculated in the daily INS/OUTS of fluid management.

20. Tender loving care 

  • Tender loving care by staff is very important for patient comfort, stress management and encourages eating.

Record charts

  • Record all pertinent details.
  • Display results so that trends can be easily noted.
  • Do not overlook sleep time and pain scoring.
  • Other types of monitoring may be necessary, eg coagulation times or hormone assays.
  • Cheaper sophisticated monitoring equipment is more available and should increase the level of care, ie combined electrical units are available for monitoring a number of physiological parameters.

Further Reading


Refereed papers

  • Recent references from PubMed and VetMedResource.
  • Purvis D & Kirby R (1994) Systemic inflammatory response syndrome: septic shock.​ Vet Clin North Am Small Anim Pract 24 (6), 1225-1247 PubMed.

Other sources of information

  • Kirby R (1995) Septic Shock. In: Kirk's Veterinary Therapy XII Small Animal Practice. Bonagura J D & R W Kirk, editors, W B Saunders, Philadelphia, pp 139-146.