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Specialty Areas: energy needs for TPN/EN
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11/17/03 09:18 PM | Edit ReplyReply   |    energy needs for TPN/EN
sarklein77
2 Posts
AZ
Registered Dietitian

Can anyone give me a consistent answer to this question: how would you calculate calorie/protein needs for an overweight/obese patient (>125% IBW) on TPN/EN? How about for an underweight patient (<90% IBW)? Would you use the actual body weight or adjusted body weight?

12/06/03 10:25 PM | Edit ReplyReply   |    RE: energy needs for TPN/EN
Marianne
12 Posts

Registered Dietitian


    Posted by sarklein77:
    Can anyone give me a consistent answer to this question: how would you calculate calorie/protein needs for an overweight/obese patient (>125% IBW) on TPN/EN? How about for an underweight patient (<90% IBW)? Would you use the actual body weight or adjusted body weight?

Calculating calorie and protein needs varies based on current and past weight histories, medical histories and diagnosis, and degree of stress. 15 to 20 calories per kilogram of body weight can be used for weight reduction, but an overweight catabolically stressed patient would probably require more calories and/or protein. Nitrogen balance studies will more accurately determine protein needs rather than assuming the usual 1.2 - 2.0gm/kg/wt. Balance studies work well in patients on TPN/Enteral feeds since the exact amount of protein delivery is known. This will also prevent overfeeding protein, which can cause azotemia, increased respiratiory drive to breathlessness and altered drug kinetics. You must always be careful not to overfeed calories, as this could cause complications, such as preventing optimal vent weaning by increasing CO2 production (most of who are on TPN or enteral support), hepatic dysfunction and fat synthesis nd storage. Metablic cart studies will determine actual REE and is appropriate for severe illness or injury.

Actual body weight should never be used for the obese. Fat stores are not metabolically active. An adjustment should be made to compensate. The old method was adjusting by 25%. More recently I've read to adjust .32 for a female and .38 for a male. For an underweight patient, <90%, 25-30 calories/kg would probably be too low, however all the surrounding factors would be taken into account before just guessing 30-35-40-or possibly 45 calories/kg.


08/18/04 07:09 AM | Edit ReplyReply   |    RE: energy needs for TPN/EN
colinedge
5 Posts
Corner Brook
Registered Dietitian

The way I was taught in internship and still use today is the following.

If pt is > than 115% IBW, use adjusted body wt= Ideal + (Actual - Ideal)/4. This wt is then used in HB Eqn with a stress/activity factor. To calculate protein requirements, I would use the upper end of ideal wt range (BMI=25). Possible problem with thisis that it assumes overwt individuals do not have an increased muscle mass and is also assumes protein not required to maintain fat tissue reserves. I would use actual body wt for an underwt indiviual but use the lower end of Ideal weight range to calculate the protein requirements. If pt is ventilated, there is a version of the Ireton-Jones equation for energy that uses actual BW but accounts for obesity. Colin Edgecombe, R.Dt. Western Memorial Hospital cedgec@healthwest.nf.ca


    Posted by sarklein77:
    Can anyone give me a consistent answer to this question: how would you calculate calorie/protein needs for an overweight/obese patient (>125% IBW) on TPN/EN? How about for an underweight patient (<90% IBW)? Would you use the actual body weight or adjusted body weight?

08/19/04 10:42 PM | Edit ReplyReply   |    RE: energy needs for TPN/EN
black16
120 Posts
Columbus
Registered Dietitian

I personally do not like to use Harrison Benedict, because it restricts your TPN/TF regimen to one value and not a range. However, that's the nice thing about practicing dietetics, one never has to do something in one uniform manner, so long as he/she causes no harm, and the patient's problem(s) is/are addressed/treated. Personally, if I do an Adj BW based on the following: patient is >120%IBW, then us an Adjusted Body Weight. Adj BW= CBW-IBW=X, allow 25% the value of X (do so by multiplying X by 0.25) and add back to CBW. I allow usually 25-30kcals/kg Adj BW, or sometimes 30-35kcals/kg Adj BW, if the kcals/kg of actual BW end up being extremely low, such as 3,000ml/day. If someone is in this position, I may allow only 25-30ml/kg Adj BW or 30-35ml/kg Adj BW, again depending on the situation. In time, I think we all become more confident and comfortable using our own spin on calculations.

    Posted by colinedge:
    The way I was taught in internship and still use today is the following.

    If pt is > than 115% IBW, use adjusted body wt= Ideal + (Actual - Ideal)/4. This wt is then used in HB Eqn with a stress/activity factor. To calculate protein requirements, I would use the upper end of ideal wt range (BMI=25). Possible problem with thisis that it assumes overwt individuals do not have an increased muscle mass and is also assumes protein not required to maintain fat tissue reserves. I would use actual body wt for an underwt indiviual but use the lower end of Ideal weight range to calculate the protein requirements. If pt is ventilated, there is a version of the Ireton-Jones equation for energy that uses actual BW but accounts for obesity. Colin Edgecombe, R.Dt. Western Memorial Hospital cedgec@healthwest.nf.ca


      Posted by sarklein77:
      Can anyone give me a consistent answer to this question: how would you calculate calorie/protein needs for an overweight/obese patient (>125% IBW) on TPN/EN? How about for an underweight patient (<90% IBW)? Would you use the actual body weight or adjusted body weight?


08/20/04 07:47 PM | Edit ReplyReply   |    RE: energy needs for TPN/EN
black16
120 Posts
Columbus
Registered Dietitian


    Posted by black16:
    I personally do not like to use Harrison Benedict, because it restricts your TPN/TF regimen to one value and not a range. However, that's the nice thing about practicing dietetics, one never has to do something in one uniform manner, so long as he/she causes no harm, and the patient's problem(s) is/are addressed/treated. Personally, if I do an Adj BW based on the following: patient is >120%IBW, then us an Adjusted Body Weight. Adj BW= CBW-IBW=X, allow 25% the value of X (do so by multiplying X by 0.25) and add back to CBW. I allow usually 25-30kcals/kg Adj BW, or sometimes 30-35kcals/kg Adj BW, if the kcals/kg of actual BW end up being extremely low, such as 3,000ml/day. If someone is in this position, I may allow only 25-30ml/kg Adj BW or 30-35ml/kg Adj BW, again depending on the situation. In time, I think we all become more confident and comfortable using our own spin on calculations.

08/24/04 05:52 PM | Edit ReplyReply   |    RE: energy needs for TPN/EN
colinedge
5 Posts
Corner Brook
Registered Dietitian

You certinaly can generate a range by using a stress factor range. If you are aware of an energy equation that generates a range please let me know. Harris benedict equation, using n IBW or an AdjBW has been shown to have the highest correlation with Metabolic Cart measured energy expenditure in critically ill obese individuals (>120 % of ideal body wt)(when compared to 11 other predictive equations). The addition of a stress factor to the equation corrects as the correlation tends to underestimate resting energy needs. See Support Line, 23 (2):18-24


    Posted by black16:
    I personally do not like to use Harrison Benedict, because it restricts your TPN/TF regimen to one value and not a range. However, that's the nice thing about practicing dietetics, one never has to do something in one uniform manner, so long as he/she causes no harm, and the patient's problem(s) is/are addressed/treated. Personally, if I do an Adj BW based on the following: patient is >120%IBW, then us an Adjusted Body Weight. Adj BW= CBW-IBW=X, allow 25% the value of X (do so by multiplying X by 0.25) and add back to CBW. I allow usually 25-30kcals/kg Adj BW, or sometimes 30-35kcals/kg Adj BW, if the kcals/kg of actual BW end up being extremely low, such as 3,000ml/day. If someone is in this position, I may allow only 25-30ml/kg Adj BW or 30-35ml/kg Adj BW, again depending on the situation. In time, I think we all become more confident and comfortable using our own spin on calculations.

      Posted by colinedge:
      The way I was taught in internship and still use today is the following.

      If pt is > than 115% IBW, use adjusted body wt= Ideal + (Actual - Ideal)/4. This wt is then used in HB Eqn with a stress/activity factor. To calculate protein requirements, I would use the upper end of ideal wt range (BMI=25). Possible problem with thisis that it assumes overwt individuals do not have an increased muscle mass and is also assumes protein not required to maintain fat tissue reserves. I would use actual body wt for an underwt indiviual but use the lower end of Ideal weight range to calculate the protein requirements. If pt is ventilated, there is a version of the Ireton-Jones equation for energy that uses actual BW but accounts for obesity. Colin Edgecombe, R.Dt. Western Memorial Hospital cedgec@healthwest.nf.ca


        Posted by sarklein77:
        Can anyone give me a consistent answer to this question: how would you calculate calorie/protein needs for an overweight/obese patient (>125% IBW) on TPN/EN? How about for an underweight patient (<90% IBW)? Would you use the actual body weight or adjusted body weight?



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