Guest Post: A closer look at hypotension

by Robert S. Gold, MD

If a coder reviews the chart of a patient in the emergency department (ED) or intensive care unit with documented symptoms, such as fever (or low temperature), elevated white cell count (or low white cell count), altered mental status, evidence of an infection (e.g., pneumonia, pyelonephritis, a rigid abdomen with speculation of diverticulitis or perforation of another intestinal organ), and hypotension, remember the following thought process.

The chart may show that the physician gave the patient a bolus of saline (250–500 cc), or Ringer’s lactate and another bolus. If the patient perks up and feels better—and the creatinine drops from 5.4 to 2.7—then the patient likely had hypotension due to severe dehydration (ICD-9 code 276.51).

The rapid change in creatinine levels show that the patient was, indeed, pretty dehydrated and is coming back toward better levels.  However, if the creatinine does not return to the patient’s baseline within 24 hours of fluid resuscitation and remains significantly elevated over the patient’s baseline for more than 24 hours, there was likely acute renal damage or acute kidney injury.  The mechanism of the damage likely depends on the presence of absence of shock (in giving the physician a clue if it represented acute renal tubular necrosis or ATN).

The patient may have had sepsis (ICD-9 codes 038.9 and 995.92) from that infectious process and metabolic encephalopathy, explaining the altered mental status (ICD-9 code 348.31) due to the sepsis with acute renal failure.

If the patient does not respond to the fluid challenge, and the physician starts the patient on pressors (ICD-9 code 00.17), such as levophed, dobutamine, or dobutrex, coders may assume the patient is probably in shock. The question is, was it hypovolemic shock (ICD-9 code 785.59) or septic shock (ICD-9 code 785.52)? The physicians should document the presence of shock and the etiology of it in this case.

Sometimes in the ED, coders see hypotension related to the positional change of a moderately to severely dehydrated patient. The physician may have called it orthostatic hypotension. When the physician’s documentation shows that the patient was dehydrated (ICD-9 code 276.51), and the patient responds to IV fluids, then code the dehydration. However, if the physician administers several boluses of fluid to this severely dehydrated patient and the creatinine levels takes over a day to significantly decrease, as above, think of acute renal failure or acute kidney injury (ICD-9 code 584.9) due to dehydration.

Consider the same scenario in the ED with a patient who is vomiting blood or having massive bloody stools. There is a significant bleed somewhere. If the physician documented hypotension and the administration of large volumes of saline or Ringer’s lactate, with type-specific or uncrossmatched blood, and orthostatic vital signs are observed, think of hypovolemia (ICD-9 code 276.52).

If the patient requires pressors to maintain perfusion and blood flow, perhaps there was hemorrhagic shock (ICD-9 code 785.59)—but don’t code it as orthostatic hypotension. The code for orthostatic hypotension is a chronic autonomic nerve condition—not acute volume changes.

Hypotension can happen in patients who have documented chest pain. The condition may be accompanied by one or more of the following:

1. Documented congestive heart failure (ICD-9 code 428.0). Query the physician regarding the acuity and the functional abnormality.
2. Arrhythmia such as:
   1. Bradycardia with pulse rates about 45 or lower (ICD-9 code 427.89).
   2. Ventricular tachycardia (ICD-9 code 427.1).
   3. Ventricular fibrillation (ICD-9 code 427.4), in which case the physician likely used a defibrillator on the patient.
3. Acute coronary syndrome (ACS) (ICD-9 code 411.1). Was it a myocardial infarction (MI)? Check the troponins. If they are higher than the 99th percentile of high normal for your hospital’s lab and the patient had symptoms consistent with acute MI, it was an MI (ICD-9 code 410.x1). Or was it unstable angina (ICD-9 code 411.1) due to either a ruptured plaque (ICD-9 code 414.01, if the patient didn’t have a coronary artery bypass graft) or some secondary cause (anemia or shock or tachycardia, etc.)?

A patient starting beta-blockers or multiple medications, such as sleeping pills, antidepressants, seizure medications, and pain medications, may suffer from hypotension.  Physicians may discontinue or substitute these medicines until the patient can stand up without falling down. There are many potentially necessary E codes with the iatrogenic hypotension code assigned (ICD-9 code 458.29).

A patient who recently underwent dialysis could also develop hypotension if the dialysis drew off a little too much volume or the patient’s autonomic nervous system is very sensitive to volume changes, causing the patient to pass out (ICD-9 code 458.21).

Patients with true autonomic nervous system dysfunction associated with diseases as below may also suffer from hypotension, especially when changing position (orthostasis):

1. Diabetes, most commonly in the United States (ICD-9 codes 250.6x, 337.1, and possibly 458.8).
2. Amyloidosis (ICD-9 codes 277.39 and 337.1—357.4 is a different condition).
3. Familial dysautonomia (ICD-9 codes 742.8 with 337.1).
4. Multiple system atrophy. There is no specific code for this. It is a neurodegenerative disease that manifests as Parkinsonism, cerebellar dysfunction, and autonomic disturbances.

Be wary of “hypotension” because of all its possible causes, and be wary of “orthostatic hypotension” because that is rarely a primary condition.

Editor’s note: This article was published in the September issue of Briefings on Coding Compliance Strategies, and featured on the ACDIS website as its October 2009 article of the month. It was updated by Dr. Gold for publication on the ACDIS Blog. Dr. Gold, at the time of this article's release, was CEO of DCBA, Inc., a consulting firm in Atlanta that provides physician-to-physician programs in clinical documentation improvement and training of CDI specialists to support the medical staff.