Critical values and troubleshooting Shaimah Al-Failakawi

What is a Critical test? A test that requires rapid communication of the result to guide with further management decisions of medical urgency irrespective of whether it is normal, significantly abnormal or critical.

Difference between critical and abnormal results Abnormal Results - Significantly abnormal results which are not life threatening, but may result in significant patient morbidity or irreversible harm or mortality. They require medical attention and follow-up action within a medically justified timescale, and for which timing is not as crucial as for critical results.

What are critical values? Also called panic or alert results Test results falling significantly outside the normal range and/or may represent life- threatening values, even from routine tests. These tests require rapid communication of results to the responsible caregiver. A delay in taking action responding to the result may result in a serious adverse outcome for the patient. The use of the term ‘panic’ is discouraged.

Types of critical values Repeated critical result- Subsequent or Sequential critical results which have improved from a previous critical value and the provider is aware of the previous value. Clinical judgment, based on patient status, determines if these results are to be communicated to the physician as a critical result. Expected/known critical result- Critical results expected based on the department (e.g. ICU, casualty) and/or diagnosis. New critical values

Actions performed when encountering critical values Results from critical tests and critical results shall be verified in the laboratory to rule-out pre- analytical errors in sample collection and handling. Ensuring the analytical quality by checking the quality control results on the analysers and repeating the tests, if needed, on another analyser. Check the patient’s cumulative results for repeat critical values.

Communicating critical tests or results The critical result shall be communicated to the responsible licensed caregiver or the physician whom requested the test. When the patient’s responsible licensed caregiver is not available within the allotted time frame (15-30 minutes for chemistry and haematology stat tests), the information will be reported to an alternate responsible licensed caregiver. For inpatient setting, it is acceptable for critical test results and critical results to be communicated to authorized staff members (nurses) whom would then be accountable for communication to the responsible licensed caregiver. In the event that a patient’s provider cannot be reached or successful contact cannot be established, the on-call laboratory physician will be contacted and informed. The on-call physician shall be conveyed the critical result. Verification of clinician notification should be subsequently conveyed back to the laboratory technologist and documented.

Read-back policy A “read-back” of the information (patient full name, Identification number and critical result) by the personnel on the receiving end. The staff member receiving the test result will write down the result (if possible) and read it back to the technologist or physician providing the result. The technologist or physician providing the test result will confirm the information was read back correctly and shall document the process was performed on the LIS. Documentation of the critical value notification shall be indicated on the LIS report note section and shall include the name of the authorized staff that received the call and thus the critical result as well as the time the staff member was informed.

Repeated/known critical values In situations where the critical value is expected based on the department (e.g. ICU, emergency departments), diagnosis (expected critical), or there was an improvement of the critical value from a previous value and the provider is aware of the previous value (repeated critical), the laboratory staff shall not inform the responsible caregiver. These values shall be documented on the LIS report note section and will be included as part of the ‘informed critical results' during indicator measurement. If a noncritical test result occurs after a critical result, any subsequent critical results are considered new and shall be informed to the authorized caregivers. Therefore these critical results are called the first critical values after a noncritical.

Critical values- clinical chemistry Test Name Value is Less Than Value is More Than Unit Acetaminophen - 990 umol/L (after 4 hrs) Ammonia >1 year < 1 year 200 100 µmol/L Bicarbonate (serum) 10.00 40.00 mmol/l Bilirubin (serum) neonatal first 5 days 340 Calcium (serum) 1.5 3.5 mmol/L Carbamazepine 63 Digoxin 5.2 nmol/L Glucose Plasma – fasting CSF 2.2 25 Lactate Serum 2.8 5.0 Magnesium 0.4 3.7 Osmolality Blood 265 390 mOsm/kg Phenobarbitone 258 Phenytoin 126 Phosphorus 0.36 Potassium (serum) 2.5 6.5 Sodium (serum) 120 160 Theophyline 111 Valproic Acid 1041 *Tacrolimus (FK506) 15.0 mg/L *(significant abnormal), timelines depends on the sample status (routine monitoring/stat).

Critical values- hematology (adults) Hematology Critical Values for Adult Patients Test Critical Values Low High Total WBC ANC < 2.0 x 109/L < 0.5 >80 x 109/L - Hb < 70 g/L > 190 g/L Plt < 20 x 109/L > 1000 x 109/L Blood Film Presence of malarial parasites Presence of blast cells Presence of fragmented RBCs (with anemia and thrombocytopenia) INR * > 6.0 APTT > 120 seconds Fib. < 1.0 g/L

Critical values-hematology (children under 12 yrs of age) Hematology Critical Values for Infants and Children Under 12 Years of Age Test Age Range Critical Values Low High Total WBC ANC All < 2.0 x 109/L < 0.5 > 50.0 x 109/L - Hb Day 0 < 80 g/L > 220 g/L Day 1-30 > 230 g/L 1month–12years > 200 g/L Plt Day 0-60 < 50 x 109/L > 1000 x 109/L 2month–12years < 20 x 109/L Blood Film Presence of malarial parasites Presence of blasts Presence of fragmented RBCs (with anemia and thrombocytopenia) INR > 4.0 APTT > 90 seconds Fib < 1 g/L

Significant results-microbiology Test Critical Result Blood Culture Any positive culture will be called to the patient’s nurse, or if unavailable, the charge nurse. The nurse is responsible for notifying the physician. In addition a written report will be released. CSF Cultures and CSF Gram Stains Positive CSF cultures and CSF gram stains will be called to the patient’s nurse, or if unavailable, the charge nurse. The nurse is responsible for notifying the physician. In addition a written report will be released. Acid-fast Bacilli Smears Positive Blood Smears Positive for malarial parasites Ocular Specimens Culture positive for Neisseria gonorrhoeae, Neisseria meningitidis, Pseudomonas aeruginosa Ear Specimen Pseudomonas aeruginosa of ear swab Wound Swabs Group A Streptococcus of wound swab Enteric Specimens Escherichia coli 0157:H7, Vibrio cholerae, Shigella Dysenteriae type I, Salmonella typhi, Salmonella paratyphi A and B Highly Aggressive Organisms Bacillus anthracis, Brucellaspp, Yersinia pestis, Francisellatularensis, Burkholderia mallei, Burkholderiapseudomallei, presumptive Clostridium botulinum, etc. First-time Isolates Vancomycin-resistant enterococci (VRE) or methicillin-resistant Staphylococcus aureus(MRSA) from clinically infected sites, but not from screening sites, multidrug-resistant Pseudomonasaeruginosa, Acinetobacterbaumannii and carbapenemase-resistant Enterobacteriaceae (CRE).

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