NPH Insulin Dosing for Severe Hyperglycemia in Tube-Fed Patient
Start NPH insulin at 24-32 units administered in the morning to address the severe hyperglycemia (344 mg/dL) in this patient receiving cycled tube feeding.
Rationale for NPH Dosing Calculation
Given this patient's clinical scenario with severe hyperglycemia despite 6 units of Novolog, a more aggressive basal insulin approach is warranted:
- For severely hyperglycemic patients, initial insulin dosing should be 0.3-0.4 units/kg/day 1
- At 81 kg body weight, this calculates to 24-32 units total daily insulin requirement 1
- NPH should be administered in the morning to provide intermediate-acting coverage that peaks in 4-6 hours, matching the carbohydrate load from the 12-hour cycled tube feeding 2, 3
Specific Dosing Recommendation
- Initiate NPH at 0.3 units/kg = 24 units given in the morning (conservative starting point) 2
- For this degree of hyperglycemia (344 mg/dL), consider the higher end: 0.4 units/kg = 32 units 1
- The 6 units of Novolog already given was inadequate, suggesting significant insulin resistance requiring more aggressive basal coverage 2
Additional Prandial Coverage for Tube Feeding
Since this patient receives 94 grams of carbohydrates over 12 hours in cycled feeding:
- Add scheduled rapid-acting insulin (Novolog) at 4-6 units every 8 hours to cover the continuous carbohydrate load 4
- Use a ratio of approximately 1 unit per 10-12 grams of carbohydrate for tube feeding coverage 2, 4
- This provides approximately 12-18 units of prandial insulin daily in addition to basal NPH 4
Correction Scale for Persistent Hyperglycemia
For blood glucose of 344 mg/dL, the correction insulin was insufficient:
- Blood glucose 301-350 mg/dL should receive 10-12 units of rapid-acting insulin 2, 4
- The patient only received 6 units, explaining the inadequate response 2
- Use correction factor of 1 unit per 20-25 mg/dL above target (using 1800 rule) 2, 4
Monitoring and Titration Protocol
- Monitor blood glucose every 4-6 hours while adjusting the insulin regimen 2, 4
- Increase NPH by 2 units every 3 days if fasting glucose remains above 140 mg/dL 3, 4
- Target blood glucose range: 100-180 mg/dL 2
- If hypoglycemia occurs, reduce NPH dose by 10-20% 2, 3
Critical Pitfalls to Avoid
- Do not underdose insulin in severely hyperglycemic patients - the initial 6 units of Novolog was clearly insufficient for a blood glucose of 344 mg/dL 2
- Failing to provide both basal (NPH) and prandial coverage for tube feeding will result in continued hyperglycemia 4
- Not timing NPH administration with the tube feeding schedule can lead to hypoglycemia during the 12 hours off feeding 2, 3
- Monitor closely for hypoglycemia during the 12-hour period when tube feeding is off, as NPH will still be active 3, 4