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Coding and Documentation Is Crucial in Supporting Critical Care Services

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Documentation should paint a picture of the patient’s condition. Medical necessity drives every patient encounter. In fact, the Comprehensive Error Rate Testing (CERT) Program states, “Medical necessity of a service is the overarching criterion for payment in addition to the individual requirements of a CPT code.”1 Diagnosis coding is very important for any specialty but critically important when managing a critical care patient. Coding and documentation should tell the payer what and why— what services are performed and the reason for providing the service.

Critical care documentation should always include: 

  • The organ system(s) at risk 
  • Which diagnostic and/or therapeutic interventions were performed, including rationale 
  • Critical findings of laboratory tests, imaging, ECG, etc., and their significance 
  • Course of treatment (plan of care) 
  • Likelihood of life-threatening deterioration without intervention

A patient who is critically ill typically has a laundry list of comorbid conditions. When coding for critical care services, it is appropriate for the physician to code and report the patient’s underlying or comorbid conditions even if the physician is managing only one condition, such as respiratory distress, acute myocardial infarction, stroke, injury or any condition that requires critical care.

International Classification of Diseases, 10th Edition, Clinical Modification (ICD-10-CM) can accommodate more specificity when describing acute, subacute and chronic conditions. Documentation of the reason for providing the critical care services should include the principle/first listed diagnosis followed by any comorbidities that affect the patient’s care. Often the physician reports only the condition he/she is managing, but this does not always provide a true picture of the patient’s condition.

For example, review the following case: A 55-year old man has long-standing insulin-dependent type 1 diabetes. He has been critical for the past three days. He presented in diabetic ketoacidosis and septic shock due to acute pyelonephritis. He has developed acute kidney failure, likely due to a combination of his compromised baseline renal function. Baseline creatinine is 1.8. Skin examination reveals a grade 4 sacral decubitus ulcer, which was present on admission and is being managed by plastic surgery. He has been intubated and ventilated for five days (SpO2 73% on 100% nonrebreather mask with respiratory rate 28 breaths/ min). Blood cultures are positive for Staphylococcus aureus sepsis. The critical care physician is going to continue treatment with IV ciprofloxacin and vancomycin. Consultation is ongoing with plastic surgery for the sacral decubitus ulcer, as is the use of a rotating bed. Time spent in critical care is 45 minutes.​

CPT coding: 
99291 Critical care, first 30-74 minutes

Diagnosis (ICD-10-CM) coding: 
E10.10 Type 1 diabetes mellitus with ketoacidosis without coma 
N10 Acute pyelonephritis 
A41.01 Sepsis due to methicillin-susceptible Staphylococcus aureus R65.21 Severe sepsis with septic shock N17.9 Acute kidney failure, unspecified 
L89.154 Pressure ulcer of sacral region, stage 4 (present on admission)​

In this example, the critical care physician is not managing the pressure ulcer, but it does affect the patient’s management and may be reported as an additional diagnosis.

Here is another example: 
A man is brought to the emergency department after developing severe shortness of breath. He is admitted to critical care in severe respiratory distress and acidosis. The critical care physician intubates him and begins ventilator management. The patient also has primary colon cancer of the descending colon, which is managed by gastroenterology. The critical care physician spends 35 minutes managing this patient.

CPT coding:
99291 Critical care, first 30-74 minutes Note: Intubation and ventilator management are included in critical care.

Diagnosis (ICD-10-CM) coding: 
J80 Acute respiratory distress 
E87.2 Acidosis 
C18.6 Malignant neoplasm of descending colon

Even though the critical care physician is not managing the patient’s colon cancer, it is a comorbidity that affects the patient’s management and may therefore be reported.

Documentation is a key factor in selecting the most accurate diagnosis and specificity to support medical necessity and to support all critical care services. It is not enough to simply list all the diagnoses managed or those that affect patient care; they must be clearly identified in the documentation to validate the care provided.

Critical Care Coding and Documentation Tips 
1. The patient must have a critical diagnosis or symptom.
2. There must be a critical diagnosis or symptom(s), regardless of the area in which the physician provides services.
3. Care provided must require complex medical decision-making by the physician.
4. The physician must clearly document in the medical record the time spent providing critical care.
5. Document in detail all procedures performed during the patient encounter that are part of critical care.
6. Document all procedures and services in detail that are not part of critical care.
7. Document and code all diagnoses and comorbidities that affect patient care.
8. Document the acuity/severity of all diagnoses (e.g., acute, chronic, acute-on-chronic, exacerbation).
9. List all conditions related to the underlying cause, if known (e.g., sepsis due to pneumonia).
10. Clarify in the documentation any conditions that are present on admission.
11. Document any suspected or rule-out conditions along with signs and symptoms. Confirm any uncertain diagnoses at the time of discharge.

Documentation is the key element in supporting medical necessity for a procedure or service. The diagnosis code is a critical factor to support any claim submitted to the payer. Understanding how to document to support medical necessity should be a priority for every physician who manages critical care. 

Common Diagnoses in Critical Care 
Listed below are some common conditions typically managed in critical care, with key documentation tips to help the practitioner document the patient encounter to support medical necessity. This list is not all-inclusive.

Additional Resources
ICD-10-CM Official Guidelines for Coding and Reporting
FY 2017
ICD-10-CM 2017 Codebook