Friday 12 May, 2006

Standard post-operative fluid management in adults

Posted in Medicine, Michael Tam, Surgery, Wards at 17:07 by Michael Tam

Index: Intravenous fluid therapy :: Printer friendly

Original article by: Michael Tam

Not enough fluids?

Update (19 June 2011): This article is not consistent with current best evidence.  Please see the following comment. [Michael Tam]

Despite getting plenty of fluids intraoperatively, most patients are usually dehydrated after an operation. There are several reasons for this:

  1. Poor oral intake prior to fasting for theatre (e.g., due to anxiety)
  2. Prolonged fasting period pre-operatively (e.g., operating theatre delayed)
  3. Fluid and blood loss intra-operatively
    • direct blood loss
    • exposure of large internal surfaces to the heat and light of the theatre lights
    • fluid loss from respiration while intubated
  4. Post-operative ileus with third space losses of fluid into the bowel (especially after intra-abdominal and bowel surgery)
  5. Post-operative intravenous fluid therapy insuffient for maintenance and replacement.

Depending on the type and length of the operation, it is not uncommon for patients to be several litres “dry” in the post-operative period. In fact, unless you have specific knowledge otherwise, it is probably safe to assume that the patient is around 1-2 litres dehydrated. These patients would usually be otherwise asymptomatic. The aim is to rehydrate the patient to euvolaemia over a 24 hour period.

For the post-operative patient without significant symptomatic dehydration (please note comment here about a clinical update):

Regimen One (minimally dehydated)

  • Bag 1: 0.9% NaCl (“normal saline”) + 30 mmoL KCl then
  • Bag 2: 0.9% NaCl + 30 mmoL KCl then
  • Bag 3: 0.9% NaCl then
  • Bag 4: 0.9% NaCl then
  • Usual IV maintenance therapy
  • Rate: Bags 1 to 4 at 166 mL/h (or q6h)
  • Results in 4 litres of saline rich fluid in the first 24 hours.

Regimen Two (more dehydrated)

  • Bag 1: 0.9% NaCl (“normal saline”) @ 250 mL/h (q4h) then
  • Bag 2: 0.9% NaCl @ 250 mL/h (q4h) then
  • Bag 3: 0.9% NaCl + 30 mmoL KCl @ 166 mL/h (q6h) then
  • Bag 4: 0.9% NaCl + 30 mmoL KCl @ 166 mL/h (q6h) then
  • Bag 5: 0.9% NaCl @ 166 mL/h (q6h) then
  • Usual IV maintenance therapy
  • Results in just over 4.5 litres of saline rich fluid in the first 24 hours.

Post-operative oliguria / significant dehydration will be covered in a separate article.

Fluid volume

Assuming the usual 70 kg previously healthy person, this means you should aim for:

  • 4-5 litres of fluid in the next 24 hours (versus the euvolaemic maintenance of around 3 litres);
  • After achieive euvolaemia / good hydration, if the patient still needs IV fluids, then the maintenance rate should suffice.

Fluid choice

For someone with a fluid deficit, that fluid is best replaced with saline rich solution. That is:

  • either 0.9% NaCl solution (Normal Saline);
  • or Hartmann’s solution.


Some surgeons say that the body spares potassium post-operatively so potassium supplementation is not required in the first 24 hours. Though this is true for the vast majority of patients, it is not universally true (e.g., and needless to say, it is in those patients that this is not true that will potentially have life-threatening hypokalaemia).

My opinion is that you should give adequate potassium replacement for patients in the first 24 hours post-operatively routinely unless there is a specific reason not to.

In procedures where there is a high likeihood of post-operative ileus (e.g., intra-abdominal surgery and bowel surgery in particular), potassium supplementation is a must as third space losses into the bowel are generally rich in potassium. Hypokalaemia, furthermore, prolongs intestinal ileus.

I would give:

  • 1 mmoL of KCl per kg of body weight in the first 24 hours
  • ~ 60 mmol KCl (for ordinary adult)
  • = 30 mmol KCl in two of the litre bags of fluid (premixed or otherwise)

Additional losses

If a patient has diarrhoea or vomiting, you need to replace this fluid on top of their maintenance and post-operative replacement fluids. You should consider this fluid as both sodium and potassium rich and so a “litre” of vomitus or diarrhoea should be replaced with a litre bag of Normal Saline + 30 mmol KCl.

Third space losses

In patients with an ileus or a small bowel obstruction (or for example, in pancreatitis), there can be large amounts (as in litres and litres) of fluid “lost” to the bowel. This fluid will be sodium and potassium rich.

Usually, you will need to aggressively replace fluid (that is, many litres a day) with saline and often with large amounts of potassium.

Patients who are eating

Usually, patients who are eating but require “supplemental” fluids (i.e., inadequate oral intake) will only require small amounts of fluid. In general, intravenous potassium replacement is not required for these patients (even if they are hypokalaemic, you can usually use oral supplementation).

Try to calculate the amount of water actually required. For example, if they need 1L of water in addition to oral intake, then only give 1 litre in a day (as normal saline or dextrose solution). If no other intravenous access is required and intravenous access is difficult, consider a subcutaneous line (generally a maximum rate of fluid at about 80 mL/h). Do not put a dextrose solution subcutaneously.

Updated: Michael Tam (27 June 2009)

Please read the disclaimer


  1. Ayda said,

    I am a general surgeon from sudan i would like to know about recent advances

  2. Michael Tam said,

    I’m not aware of any particular advances in post-operative intravenous fluid therapy apart from adequate hydration, both with intra-operative replacement and in the immediate post-operative period.

    Both Hartmann’s solution and 0.9% NaCl solution (i.e., “normal saline”) are recommended. Consider post-operative hypokalaemia. Avoid the use of colloidal solutions.

    • drrashid said,

      postoperative patients we can separate the fluid requirement in three parts
      1.replacement of defecit
      2.replacement of ongoing loses
      3.maintainance fluid.. which is daily fluid requirement

      the best regamen to use is every two sweets (D 5%) followed by one sore (normal saline)

  3. Dan said,


    I’ve studying for an exam that’s tomorrow morning (yay)… This article seems to contradict a textbook I’m reading which is trying to tell me that post-operative HPA axis activity leads to reduced Na loss and increased K loss (but a net retention of H2O, presumably but tacitly by way of SIADH). Therefore, it suggests I consider giving 2L of 5% dextrose as standard post-op fluid maintainence, with electrolytes given as appropriate based on serum electrolytes.

    You guys are saying I need to give EXTRA fluid, and that it should all be normal saline! What gives!??


  4. Michael Tam said,

    Remember that the patient has a real salt and water deficit post-operatively and if they are nil by mouth (which will usually be true in the 24 hours after surgery for an adult), they have no other sources of water or salt. So, it is for the most part appropriate secretion of ADH.

    And thus, it is simple. You should replace both the water and salt. The increased production of ADH normalises as the patient reaches euvolaemia. For personal and practical experience, I can tell you that only giving water (i.e., 5% dextrose solution) post-operatively is incorrrect and you WILL precipitate hyponatraemia with that strategy.

    In fact, have a look at the two articles from the Sydney Children’s Hospital (Randwick) here (see end of the article). Children with gastroenteritis (i.e., also a real fluid deficit) are in fact prone to SIADH (or a SIADH like disorder) and hyponatraemia. Using a dextrose solution would be the worst possible thing you can do in these children. 0.9% NaCl is the fluid of choice in these children, and this has been born out by study data (see the second article)

    It is an analogous situation for the post-operative patient.

    BTW, which textbook are you using?

  5. JB said,

    I’ve seen D5 1/2 NS w/ 20 KCL for the most part post-op. Maybe this is a good compromise.

    • EC said,

      This it was is rx’d all the time post-op . I have alwauys been confused by the physiology of post op fluids. People seem VERY reluctant to use NS rather than their standard D5 1/2NS — and D5 1/4% NS in kids post op and for maintenance.

      What is the reasoning? I’m not sure I am understanding the physiology well enough to order NS.

  6. Patel said,

    hello sir,

    i am medical student from India. i am in my final you said that postoperatively Normal saline and potassium will suffice need of body fluids and electrolytes, what about calorie requirements?

    in my college post operatively 2lits of 5%dextrose with abt 1lits of normal saline are given for initial 24hrs post operatively.

    what is your comment on this regime?


  7. Michael Tam said,

    I don’t usually think too much of caloric requirements as most people have more than adequate reserves for what is a 1-2 day fast.

    Remember, a 1 L bag of 5% dextrose only contains 50 g of glucose which is minimal.


  8. Asma said,

    hey i am a first year resident in HMC

    We use 2L of lactated ringer with 1L D5 water…. is this the recipe of murder!!????

  9. Michael Tam said,

    That’s not an unreasonable regimen. However, if the post-operative patient is somewhat dehydrated, then they may need more than 3 litres of fluid in the first 24 hours.

  10. dr mouli said,

    hi im doing my internship in pesimsr ,india.regarding fluid management regimens 1&2 u did not mention 5%dextrose.sodium crosses vascular compartment &hydrates ecf but it will not cross the cell membrane to enter the cellular compartment hence 5%D should be given along with 0.9%NS.Are there any control studies regardig the use of potassium in fluid resusitation postoperatively stating that it is beneficial

  11. Michael Tam said,

    Actually, I do not agree with your first remark.

    In post-operative dehydration, there is a real deficiency in both sodium and water and thus, 0.9% NaCl solution (or Hartmann’s solution) is the best fluid to give until euvolaemia.

    The sodium content in 0.9% NaCl helps it stay in the intravascular space longer and thus improves perfusion of critical organ systems (e.g., the kidneys). However, at the end of the day water will traverse through all compartments to where it is needed. Dextrose solution is useless for maintaining vascular volume due to your exact reasoning. It basically acts as free water so rapidly diffuses throughout all compartments. Furthermore, in the presence of water and salt deficiency, a dextrose solution infusion alone substantially increases the risk of hyponatraemia.

    If you are referring to the use of pre-mixed saline rich solution with 5% dextrose, these are not routinely available in Australia. In any case, I find the argument that adding a small amount of dextrose (5%) to 0.9% NaCl makes it a better hydrating solution not stand up to basic physiology. This glucose is metabolised within minutes of infusion and you are left essentially with plain 0.9% NaCl. Dextrose solutions are furthermore acidic and increase the risk of thrombophlebitis and pain, not to mention 5% dextrose + 0.9% NaCl solution is hypertonic.

    With regards to potassium I am not personally aware of any RCTs but I’m sure that you’ll find some studies with a Medline search. In terms of standard fluid therapy post-operatively, I am a firm believer that potassium should be given. Some operations (e.g., bowel) are particularly likely to lead to hypokalaemia and this impairs recovery. In terms of “fluid resuscitation” (i.e., rapid use of intravenous fluids for the shocked patient), the quantity of potassium used (if at all) should depend on serum levels of potassium.

  12. dr mouli said,

    thank u,my doubts regarding fluid managements hv cleared ,thank u once again

  13. janehendricks said,

    Dear Micheal,
    In our hospital we rarely use normal saline in post operative patients as all this does is dehydrate them further, Hartmans and 5% dextrose with 20 mmols of |KCL is our rehydration unless the patient is actually hyponatremic. Normal saline also contributes to the formation of an ileus postoperatively in GI surgery. If you look up Kehlet on the internet you will find a wealth of references to support this theory.

  14. Michael Tam said,

    Dear Jane,

    I tried looking up Kehlet but I could not find any substantive articles to back up your hypothesis. However, I do not agree with several of your points.

    Firstly, normal saline does not “dehydrate” post-operative patients. You simply have to go into hospital and see a dehydated post-operative patient being given normal saline to know this to be true. Furthermore, there is little physiological difference between normal saline and Hartmann’s solution, especially when given in the relatively small amounts post-operatively.

    I do not agree with using 5% dextrose in the immediate post-operative period as this most certainly does contribute to hyponatraemia.

    As far as I know, there is no reason that normal saline itself should “contribute to an ileus” post-operatively except from hypokaelaemia. As I clearly recommended in this article, I believe in potassium supplementation early in post-operative intravenous fluid therapy.

    Note: in the following, a “hypotonic” solution would include 5% dextrose and the “fractional” salines (e.g., half-NS or one-fifth-NS). Although each of these fluids are technically isotonic at time of infusion, the glucose (dextrose) component is rapidly metabolised leaving only the electrolytes and free water. Isotonic solutions include 0.9% NaCl (normal saline) and Hartmann’s solution.

    From Steele A., Gowrinshankar M., et al. (1997): (1)

    Our study findings should not be misinterpreted as suggesting that infusing hypotonic solutions has a risk similar to that of infusing isotonic solutions; in fact, the risk is larger with hypotonic infusions. For example, if 2 L of isotonic saline were infused and 1 L of urine with a sodium plus potassium concentration of 300 mmol/L was excreted, the positive electrolyte-free water balance would be 1 L. In contrast, if 2 L of half-normal saline (77 mmol/L) were infused, all the sodium infused would now be excreted in 0.5 L with a concentration of sodium plus potassium of 300 mmol/L and lead to a positive electrolyte-free water balance of 1.5 L.

    One results suggest that standard clinical perioperative fluid and electrolytic management should change. Hypotonic intravenous fluids should not be given during or immediately after surgery; they should only be given if a patient is hypernatremic. The minimum volume of isotonic fluid needed during and after surgery to maintain hemodynamics should be infused. Plasma sodium concentration should be checked if more than 2 to 3 L of hypertonic urine (specific gravity > 1.020) has been excreted in the first 24 hours after surgery in a person weighing 70 kg. If hyponatremia is present and a large volume of hypertonic urine continues to be excreted, two therapeutic options are available to prevent a further decrease in the plasma sodium concentration. One option is to infuse a saline solution with the same tonicity and at the same flow rate as the urine; this requires that a hypertonic solution be infused until the concentration of sodium plus potassium in the urine decreases. The second option is to decrease the concentration of sodium plus potassium in the urine by administering a loop diuretic [24, 25] or an osmotic diuretic (such as urea) [26]. A greater degree of hyponatremia can be anticipated if the patient has also consumed water, received hypotonic solutions, or retained saline before surgery (high salt intake); if a natriuretic agent (nonloop diuretic) has been acting; or if antidiuretic hormone actions (that is, pain, nausea, drugs, and stress) persist longer than 24 hours after surgery.

    Some of the best research looking at salt and potassium metabolism post-operatively recently is in children and this does give us a very good guide in adults as well. In essence, children have a relatively exaggerated response in terms of their post-operative electrolyte changes and more quickly go into hyponatraemia.

    In a systematic review of hypotonic versus isotonic fluids in children in 2006: (2)

    This systematic review indicates potential harm with hypotonic solutions in children, which can be anticipated and avoided with isotonic solutions. No single fluid rate or composition is ideal for all children. However, isotonic or near-isotonic solutions may be more physiological, and therefore a safer choice in the acute phase of illness and perioperative period.

    (1) Steele A., Gowrinshankar M., et al. Postoperative hyponatraemia despite near-isotonic saline infusion: a phenomenon of desalination. Ann Intern Med. 1997 Jun 15;126(12):1005-6.

    (2) Choong K, Kho M, Menon K, Bohn D. Hypotonic versus isotonic saline in hospitalised children: a systematic review. Archives of Disease in Childhood 2006;91:828-835

  15. Dr Trevor John Crofts said,

    I have alwaysbeen under the impression that baseline maintainance fluids post op should be 3.0 litres a day.( 2.0-2.5 litres of 5% dextrose and 0.5-1.0 Litre of 0.9% saline). I have recently come across a practice of giving nothing but Ringers Lactate 3.0 Litres a day and no other….this is 6x the normal sodium requirement. Where is the physiology in this?Regards, Trevor

  16. shanti kumar said,

    how to calculate fluid requirement ,potassium requirement in 70 kg patient undergone surgery for intestinal obstruction
    who is running temp 100 F. ,Ryles tube aspiration 250 ml, Flank drain 200ml,urine output 1800ml

  17. Michael Tam said,

    I have alwaysbeen under the impression that baseline maintainance fluids post op should be 3.0 litres a day.( 2.0-2.5 litres of 5% dextrose and 0.5-1.0 Litre of 0.9% saline). I have recently come across a practice of giving nothing but Ringers Lactate 3.0 Litres a day and no other….this is 6x the normal sodium requirement. Where is the physiology in this?

    Post-operative fluids usually make the (reasonable) assumption that the patient is dehydrated. Read the article for details.

    how to calculate fluid requirement ,potassium requirement in 70 kg patient undergone surgery for intestinal obstruction
    who is running temp 100 F. ,Ryles tube aspiration 250 ml, Flank drain 200ml,urine output 1800ml

    (1) Calculate maintenance
    (2) Calculate losses
    (3) Indwelling catheter; measure urine output hourly or second hourly
    (4) Daily serum electrolytes, urea and creatinine
    (5) Use the test results to titrate your fluid regimen.

    I’m a pharmacist reveiwing pre-printed order sets for post-op abdominal and vaginal surgery. Currently, the options for post-op IV fluid are 0.9%NaCl, 2/3D5W&1/3NS or D5W. However, some surgeons are insisting Ringer’s Lactate be put on as an option as well. This IV fluid is for maintenance and I hesitate to comply to their wishes. Would you consider Ringer’s Lactate as an appropriate post-op fluid choce?

    Yes, absolutely. Ringer’s lactate or Hartmann’s solution is an appropriate choice (with theoretical physiologically benefit when compared to 0.9% NaCl).

  18. Dan said,

    Hi Michael, thanks for your comments from 2 years ago. I didn’t get them until after my exam, but they are helping me now! I was using Devitt [] at the time.

    It really is bizarre how difficult it is to get good information on fluid therapy. I’m not surprised that your two most popular articles are one that cover it.

  19. Michael Tam said,

    In a clinical updated published in the Medical Journal of Australia in 2008, Hilton, Pellegrino and Scheinkestel (three Australian intensivists) recommend a more restrictive postoperative fluid regimen (1) than what I wrote in this article. Otherwise, their recommendations are quite similar to mine and the article is well referenced and makes good reading.

    The recommendations in my article are based on a premise of a degree of dehydration in the immediate post-operative period. If one assumes this to not be the case, then there is little difference between the volumes of fluid recommended between this article and the MJA article. The fluid type recommended remains 0.9% NaCl (normal saline).

    (1) Hilton AK, Pellegrino VA, Scheinkestel CD. Avoiding common problems associated with intravenous fluid therapy. Med J Aust. 2008 Nov 3;189(9):509-13. [Link : PDF (237 Kb)]

  20. john bradford fisher md said,

    Have any comments on postoperative management of hyponatremia,
    normokalemia, elevated CPK levels, creatinine 2.1 with a BUN 20
    K+3.5 urine specific gravity 1.020, in a postoperative abdominoplasty patient? Urine output was 700cc upon ER cath. Bibasilar pneumonia thought to be PE because of tachycardia. Initially the patient a 60 yo female was given 3-4 liters of lactated ringers over 5-6 hrs resulting in pulmonary edema and respiratory distress….does this make sense?
    VP Scan Highly suggestive of PE but no DVT found just bibasilar pneumonia after the fluids were given. ER CXR showed bibasilar atelechtasis.
    Was there justification for initiation of heparin? what other tests would confirm PE in the absence of definitive VP scan..D-Dimer FSproducts??

  21. Michael Tam said,

    The diagnosis sounds entirely consistent with pulmonary embolism. A post-operative patient, presumable obese (abdominoplasty), and tachycardia would mean a high pre-test probability of PE.

    With a ventilation-perfusion scan suggestive of PE, then frankly the diagnosis is clear. Indeed, one would arguably treat this case as a pulmonary embolism even if the VP scan came back as “intermediate probability” given the high pre-test risk.

    In the scenario, the patient was given quite large quantities of IV fluid over a short period of time and if they had a significant pulmonary thromboembolism (which can be assumed given the presence of symptoms), this would precipitate acute heart failure (increased pulmonary vascular resistance). This again is consistent with the diagnosis of PE.

    As for your question “was there justification for initiation of heparin”? Absolutely. Lower limb DVT is not found in (I think) around half of cases of pulmonary embolism and the source of the clot is presumably from the pelvic veins/venous plexuses. In your scenario, I would not consider any other tests to be necessary. If the VP scan came back as “intermediate probability”, especially if the patient had a pre-existing pulmonary condition that would make VP scan less helpful (e.g., COPD), a CT pulmonary angiogram would be the initial investigation of choice.


  22. Dr. Furat said,

    Thanks for these informations abour post operative fluids
    I have two questions
    1st> can I give 4L or 4.5L hartmann’s solution postoperatively intead of normal saline?
    and second what do you know about preoperative and perioperative fluid replacement?
    Thanks for your time

  23. Michael Tam said,

    You can generally substitute Hartmann’s solution for 0.9% NaCl in this context (as per the article). As for your second question, you will need to be more specific.

  24. Frat said,

    which type of fluid do you give and how much preoperative and intraoperative, let us say in case of intestinal obstruction in adult?
    and the same question for a child going operation let us say for intussesption?

    • Michael Tam said,

      In both settings, the patient has a surgical emergency. If they were haemodynamically unstable, then you would use resuscitation fluid therapy (there is an article on the website).

      Patients with acute bowel pathology or require a bowel operation have specific fluid needs due to the problem of third space sequestration of fluid and electrolytes. Generally, the fluid used will be electrolyte rich (i.e., likely to be 0.9% NaCl with supplemental potassium). The type and volume of fluids used will very much depend on the individual patient’s physiological parameters and clinical needs.

  25. Catherine Anderson said,

    I was wondering if you could help with my query. I cannot find any literature as to how best to resustitate a hyponatreamic patients. I am happy with maintenance fluids, but if you have a chronically hyponatraemic patients who has an operation and becomes fluid deplete what fluids are best to resus them with as you obviously do not want to increase the sodium too much/quickly.
    Dex would be useless as a resus fluid but all colloids contain a good chunk of sodium. I was faced with this last night and gave colloid bolus and hartmanns for maintenance but am not convinced I did the correct thing.



    • Michael Tam said,

      My understanding of the chronic hyponatraemia that often occurs in the elderly and as the result of some drugs like SSRIs and antipsychotics is that the osmostat has been “reset” to a lower than “normal” level. Effectively, one can consider their relative hyponatraemia to be “normal” for them.

      That is, I would resuscitate these patients as per normal, e.g., with 0.9% NaCl solution.

      I suppose that in the situation where the patient’s usual serum sodium level is unknown, using a colloidal solution is reasonable for fluid resuscitation. Once the patient is haemodynamically stable, a stategy you could employ is to return the patient to euvolaemia over 48 hours rather than 24 hours to avoid rapid changes in serum sodium. This is what I have done in the past for severely dehydrated children with hyponatraemia.


      • Dan Hernandez said,

        Sorry to add on to an old post, but one important question is:

        HOW hyponatraemic was the patient? If we’re talking about your low-level hyponatraemia (ie. >125 mmol/L) that is fairly prevalent in the elderly (see Michael’s comments re: SSRIs, antipsychotics, etc, and given the variety of polypharmacy we see in our ageing population) then 0.9% Saline or similar would be appropriate.

        IF, however we’re talking about severely hyponatremic patients (again, for a variety of causes ranging from endocrine to surgical), THEN far more weight needs to be placed on rapid replacement of intravascular volume without rapid changes in sodium concentration – otherwise we enter the realms of osmotic demyelination. Having said that, particularly in your symptomatic hyponatraemic patients, first line therapy would still be 0.9% Saline, but aiming to increase plasma sodium concentrations by no greater than 12 mmol/24 hours. Remember – for your average patient 1 litre of 0.9% Saline woud only increase plasma sodium concentration by 4-5 mmol/L.

        That’s not an answer though – just a consideration.

        PS – If considering colloidal fluid replacement, don’t forget Albumex 4% (140 mmol/L of Na versus 145 and 150 for haemacell/gelofusine respectively)

        PS Keep up the great work Michael!

        Dan H
        ICU Reg – TWH/SDMH

  26. sandrar said,

    Hi! I was surfing and found your blog post… nice! I love your blog. :) Cheers! Sandra. R.

  27. sajeesh said,

    hi Dr.Tam,great presentation in a lucid yet easily absorbable manner,as we UGstudents of india are not at all taught properly on this subject of fluid therapy.and icu management.for cooronary careand cva………thanks

  28. mac hanger said,

    Hi Dr Tam
    We have a product that gives diabetics much needed replenishment of electrolytes, vitamins, and minerals, and I was wondering if we put these supplements in the form of a popsicle, whether it would be a palatable solution for post-operative dehydration. We can do so very easily.
    I was also wondering if in your practice you give patients who are waiting from their surgeries and becoming uncomfortable a popsicle to provide sugar and small amounts of hydration prior to their surgery. Can an intake of a small amount of fluid as in a 4 ounce popsicle this cause aspiration during surgery?
    Mac Hanger

    • Michael Tam said,

      Post-operative dehydration in adults will most likely require fluid therapy at volumes larger than can be feasibly taken via a “popsicle”. Nevertheless, frozen oral rehydration fluid formulations are commonly used for children.

      It would be inappropriate giving any oral hydration prior to surgery.


  29. ben said,

    There been a lot of mystery surroounding fluid management post-op and i think you have just made things easy for me. Good job. more of this.

  30. M.A.K.Mirza,MD, said,

    Really good topic .
    i wpuld add to the regimen in postoperative Pt Glucose in form of dextrose.
    The studies showed that Pts who are NPO, getting starved , & within 24hrs they will consume whole glycogene in the liver & starts as u all know , process of glyconeogenesis & using proten as a source.
    The use of Dextros 100 gm \24 hrs will have prtein sparing effect which is important
    So add 2L of D5% in your fluid to get this effect


    • Michael Tam said,

      Thank you for your comment but I don’t agree with your premise. Even adding 2L of 5% dextrose, the total amount of glucose you are giving to the person is 100 g. This does not come close to their caloric requirements. Furthermore, most adults will tolerate fasting for up to a week without any significant health issues as long as they have adequate hydration.

      The risk of precipitating life-threatening hyponatraemia with the use of dextrose solution far outweighs the minor potential benefit of avoiding catabolism. It should not be used routinely as a post-operative fluid.

  31. Dr.B.K.Mishra said,

    Very informative site for the practitioners of peripheral hospitals.

  32. Kath said,

    What if the patient is hypoglycaemic and dehydrated post op?

  33. gertrude said,

    vanx a lot,my question was clearly answered from this text.realy this has been more than good and clear.vanx once more

  34. jo jackson said,

    Dear Dr Tam,
    Could I refer you to the GIFTASUP document section on perioperative fluids which says pretty much the exact opposite of what you are suggesting. I believe 600 mmols each of Na+ and Cl- in the first 24 hrs following surgery would be considered poor practice based on current evidence. I accept your article was written 5 yrs ago but I note correspondence as recently as 2 months ago so people need to be aware of recent changes in practice. (google GIFTASUP)
    Good website, congratulations!

    • Michael Tam said,

      Dear Jo,

      Thank you for the update. I agree that this article is no longer contemporaneous and we should be guided by best evidence. It should be noted that when this article was written (almost two years prior to it being posted on the web), it was predicated on the assumption that the patient will be dehydrated / hypovolaemic, something that was commonly true.

      I no longer have the free time to update this article to reflect current best evidence. The following are the relevant summary recommendations from the aforementioned guidelines (pp 8-9) [1]:

      Recommendation 15
      Details of fluids administered must be clearly recorded and easily accessible.

      Recommendation 16
      When patients leave theatre for the ward, HDU or ICU their volume status should be assessed. The volume and type of fluids given perioperatively should be reviewed and compared with fluid losses in theatre including urine and insensible losses.

      Recommendation 17
      In patients who are euvolaemic and haemodynamically stable a return to oral fluid administration should be achieved as soon as possible.

      Recommendation 18
      In patients requiring continuing i.v. maintenance fluids, these should be sodium poor and of low enough volume until the patient has returned their sodium and fluid balance over the perioperative period to zero. When this has been achieved the i.v. fluid volume and content should be those required for daily maintenance and
      replacement of any on-going additional losses.

      Recommendation 19
      The haemodynamic and fluid status of those patients who fail to excrete their perioperative sodium load, and especially whose urine sodium concentration is <20mmol/L, should be reviewed.

      Recommendation 20
      In high risk patients undergoing major abdominal surgery, postoperative treatment with intravenous fluid and low dose dopexamine should be considered, in order to
      achieve a predetermined value for systemic oxygen delivery, as this may reduce postoperative complication rates and duration of hospital stay.

      Recommendation 21
      In patients who are oedematous, hypovolaemia if present must be treated (as in Section 6g), followed by a gradual persistent negative sodium and water balance
      based on urine sodium concentration or excretion. Plasma potassium concentration should be monitored and where necessary potassium intake adjusted.

      Recommendation 22
      Nutritionally depleted patients need cautious refeeding orally, enterally or parenterally, with feeds supplemented in potassium, phosphate and thiamine. Generally, and particularly if oedema is present, these feeds should be reduced in water and sodium. Though refeeding syndrome is a risk, improved nutrition will
      help to restore normal partitioning of sodium, potassium and water between intraand extra-cellular spaces.

      Recommendation 23
      Surgical patients should be nutritionally screened, and NICE guidelines for perioperative nutritional support adhered to. Care should be taken to mitigate risks
      of the refeeding syndrome.

      [1] Powell-Tuck J, Gosling P, Lobo DN, et al. British consensus guidelines on intravenous fluid therapy for adult surgical patients: GIFTASUP. The British Association for Parental and Enteral Nutrition (BAPEN). Revised 7 March 2011. Click here to download PDF

  35. disgruntled med student said,

    Griffith University in Queensland Australia have linked to your website in order to ‘teach’ the medical sudents about appropriate post op fluid management.

    Could ou suggest another appropriate site to gather this information? The university are incapable of teaching us these basics themselves so we would appreciate the help.

    Disgruntled medical student.

  36. Dr. Enas Hosny said,

    Dear Michael,
    I am an anesthesiologist currently working in the uae
    I was faced with the case i will discribe below & I would like to ask for your evaluation of that case:
    a patient aged 22 years old, with body wieght of 117 kgs, & BMI 42.4 was scheduled for liposuction & abdominoplasty.
    he was put under G.A. he recieved totaol intravenous fluids of 3.3 liters of normal saline, was infused of 5 liters of tumescent fluid. the patient produced a total of 600 ml of urine & total amount of 4 liters were liposuced plus 3.5 kilograms of tissue removed.
    the patient was awake extubated & hemodynamically stable after the procedure.
    in the recovery room 22 minutes after extubation, he develpoed pulmonary edema. that responded to duiretics.
    the patient has no cardiac history.
    can you please tell me if the fluid replacment calculation for that patient was accurate. or was he over infused?
    mant thanks.

    • Michael Tam said,

      Dear Dr Hosny,

      I am not an expert on fluid physiology but it appears that he received a net excess of near 4 litres of saline rich fluid over the short period of the surgery (3.3 + 5 – 4 – 0.6 = 3.7 L).

      Using your numbers, this patient’s height is 1.66 cm so his ideal body weight (BMI = 25) is 69 kg. The average adult male blood volume is 75 mL/kg, so his total blood volume is approximately 5.2 L.

      Thus, over the course of the surgery, he received a net excess of saline of the order of 70% of his total blood volume. It is not surprisingly that he developed pulmonary oedema. The fact that he developed pulmonary oedema is an empiric demonstration that he was over-infused.

      Yours sincerely,
      Michael Tam

  37. ajay said,

    what about the use of normal saline as post op fluid in hypertensive patients with bp 180/110,,,,,,,,,,,, and secondly if we use d5 and patient develops hyponatremia on 3 or 4th day then ?

  38. prashad said,

    it s a good collection of details on that,it is easy to get it in short time,thanks for that

  39. leon said,

    Dr. Tam,

    After reading all this… I still don’t understand WHAT IS THE APPROPRIATE fluid presciption for a standard post operative patient who had abdominal surgery? Should it always be a normo-tonic solution for the first day or two or should it depend on other factors?

    What guidelines exist as to WHAT ACTUALLY to prescribe post operatively? I can’t find anything out there!

  40. Arpit Mathew said,

    Dear Dr. Tam, Sorry for disagreeing, but as a surgeon I have found that due to the increased aldosterone secretion after surgery, there is sodium retention in the early post-operative period which means that dextrose is sufficient for the first day. What do you think.

  41. Dr. Ibrahim Khalil said,

    Dear Dr. Tam,
    I am a surgeon from Bangladesh. How can only 2 l of 5%D meet 24 hrs calorie requirements ?

    • Michael Tam said,

      Dear Dr Khalil,

      It does not meet daily caloric requirements, but this is not the purpose of intravenous fluid therapy. Generally, it is not possible to meet an adult’s caloric requirements with any form of intravenous therapy through a peripherally placed cannula.

      Parental nutrition is beyond the scope of this article as it is not required in the majority of post-operative patients.

      Yours sincerely,

  42. Dr prashant said,

    Very nice information

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