Hyponatremia and surgery???

[Aether2000]

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Hyponatremia only rarely affects the conduct of anesthesia itself. I tend to think of hyponatremia with respect to the risk it imposes immediately and long term. These are some of my thoughts when considering employing a general or regional anesthetic. Correction of hyponatremia is specific to the condition and physiological status causing the hyponatremia, and is far more complex than simply starting a hypertonic saline infusion. In some situations, additional salt infused may actually worsen the situation dramatically. Most of the time, the diagnostics for the many causes of hyponatremia involve a series of lab and cardiac tests, that may lie beyond the scope of expertise of the anesthesiologist. Similarly, treatment of hyponatremia is problematic.

Chronic asymptomatic hyponatremia down to 125 mEq/l due to known causes- will proceed with urgent and emergent cases, and will do elective cases if the hyponatremia has been evaluated by an IM or PCP. For <125 will wait for some correction to occur before proceeding with elective or urgent cases. Risk to intraop or post op anesthesia- minimal. Risk to patient long term mortality- elevated

Chronic symptomatic hyponatremia- will attempt more aggressive correction of blood sodium level until symptoms resolve and Na>130 mEq/l for elective and urgent cases. Will proceed with emergent cases. Risk intraop- minimal; risk post op and long term- elevated.

Acute asymptomatic or symptomatic hyponatremia- suggests a specific cause that may in itself pose a risk to the anesthetic conduct. Attempt elimination of the cause and correction of hyponatremia.

Extreme hyponatremia- may have some effect on the anesthetic and may affect the post op recovery and long term mortality. Correct.

 

[dhb]

You can't have hyponatremia if you don't check the sodium.

 

[Noyac]

The benefit is avoiding the bad outcomes Blade's studies have mentioned.

Until somebody proves that there is no difference in outcomes between 125 and 130, one can always be accused of having caused a bad outcome by not fixing the sodium, despite having had the time to.

Maybe this has been addressed but I believe you are missing the point here. Correction of the serum Na does not improve the risks. It is the fact that the Na was low which indicates that the pt has significant comorbidities. Correcting it doesn’t reverse these comorbidities. I agree with delaying in some cases to correct the Na but don’t be fooled into thinking that the pt is now fixed. I also think the ASA 1&2 outcomes proves that these are fragile pts even when they don’t appear to be. ASAscores are so subjective.
just making sure we are all on the same page It’s not the Na but rather the pt.

 

[deleted171991]

Maybe this has been addressed but I believe you are missing the point here. Correction of the serum Na does not improve the risks. It is the fact that the Na was low which indicates that the pt has significant comorbidities. Correcting it doesn’t reverse these comorbidities. I agree with delaying in some cases to correct the Na but don’t be fooled into thinking that the pt is now fixed. I also think the ASA 1&2 outcomes proves that these are fragile pts even when they don’t appear to be. ASAscores are so subjective.
just making sure we are all on the same page It’s not the Na but rather the pt.

You can apply this to many lab values. Still we correct severe hyperglycemia before we take the patient to the OR. The thought process, in both cases, beyond worse outcomes, is also muddying of the waters. One wouldn't want the patient to have anything that could create serious periop problems (e.g. altered mental status) that add to the list of differentials.

Sodium also contributes to acid-base balance (see Stewart's strong ion theory), hence hyponatremia = tendency to acidosis. Also, let's not forget how vital it is for all cells (even if it's just 10 mEq/L inside), including cardiac tissue. So I do believe that even just correcting the Na close to the patient's usual baseline decreases the risk for badness. Of course s/he's not "fixed", the same way the diabetic who goes from sugar of 400 to 150 is not either. Many times correcting the Na goes hand in hand with improving the condition that caused it, and the latter can be more important for anesthesia (both in the hypo- and hypervolemic versions).

This type of patient is my bread and butter, and, personally, I can treat him both in the OR and the ICU. But the same way I take a septic shock patient to the OR for source control, I would take a severely hyponatremic one, too, if the benefits clearly exceed the risks.

Hyponatremia - Best Help Ever From Drs. Topf And Weingart With Additional Resources - Tom Wade MD

Note to myself: Here in this post I review hyponatremia. After each resource I’ll go over what I will do in reviewing that resource the next time I visit this page. First I listen to the first thirty minutes of EMCrit … Continue reading →

www.tomwademd.net

 

[Aether2000]

Here is one study showing hypernatremia but not hyponatremia affecting post op inpatient mortality.

S Afr Med J. 2018 Oct 2;108(10):847-851. doi: 10.7196/SAMJ.2018.v108i10.13178.
Preoperative serum sodium measurements and postoperative inpatient mortality: A case-control analysis of data from the South African Surgical Outcomes Study.
Ramburuth M1, Moodley Y, Gopalan PD.
Author information
1Discipline of Anaesthesiology and Critical Care Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban; and Inkosi Albert Luthuli Central Hospital, Durban, South Africa. [email protected].
Abstract
BACKGROUND:
Abnormal preoperative serum sodium measurements have been shown to be associated with increased postoperative mortality in US and European surgical populations. It is possible that such measurements are also associated with increased postoperative mortality in a South African (SA) setting, but this is yet to be confirmed. Establishing whether preoperative serum sodium measurements are associated with postoperative mortality could have implications for perioperative risk stratification in SA settings.
OBJECTIVES:
To determine whether preoperative serum sodium measurements are associated with postoperative mortality in SA surgical patients.
METHODS:
This was an unmatched case-control study of patient data (demographics, comorbidities, procedure-related variables, and preoperative serum sodium measurements) collected during the South African Surgical Outcomes Study. Data were analysed using recommended statistical methods for unmatched case-control studies.
RESULTS:
The study population comprised 103 patients and 410 controls. Cases were defined as patients who suffered postoperative inpatient mortality, while controls were defined as patients who did not suffer postoperative inpatient mortality. Preoperative hypernatraemia (i.e. a preoperative serum sodium measurement &gt;144 mEq/L) was independently associated with a four-fold higher risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement of 135 - 144 mEq/L (odds ratio (OR) 4.21, 95% confidence interval (CI) 1.19 - 14.83, p=0.025). Preoperative hyponatraemia (i.e. a preoperative serum sodium measurement &lt;135 mEq/L) was not independently associated with a higher or lower risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement (OR 1.39, 95% CI 0.70 - 2.76, p=0.346).
CONCLUSIONS:
Preoperative hypernatraemia, but not preoperative hyponatraemia, is a risk factor for postoperative inpatient mortality in SA surgical patients

 

[Mman]

Maybe this has been addressed but I believe you are missing the point here. Correction of the serum Na does not improve the risks.

just for clarification, we actually do not know if improving the serum sodium improves the risk but it might.

 

[Mman]

Here is one study showing hypernatremia but not hyponatremia affecting post op inpatient mortality.

S Afr Med J. 2018 Oct 2;108(10):847-851. doi: 10.7196/SAMJ.2018.v108i10.13178.
Preoperative serum sodium measurements and postoperative inpatient mortality: A case-control analysis of data from the South African Surgical Outcomes Study.
Ramburuth M1, Moodley Y, Gopalan PD.
Author information
1Discipline of Anaesthesiology and Critical Care Medicine, Nelson R Mandela School of Medicine, College of Health Sciences, University of KwaZulu-Natal, Durban; and Inkosi Albert Luthuli Central Hospital, Durban, South Africa. [email protected].
Abstract
BACKGROUND:
Abnormal preoperative serum sodium measurements have been shown to be associated with increased postoperative mortality in US and European surgical populations. It is possible that such measurements are also associated with increased postoperative mortality in a South African (SA) setting, but this is yet to be confirmed. Establishing whether preoperative serum sodium measurements are associated with postoperative mortality could have implications for perioperative risk stratification in SA settings.
OBJECTIVES:
To determine whether preoperative serum sodium measurements are associated with postoperative mortality in SA surgical patients.
METHODS:
This was an unmatched case-control study of patient data (demographics, comorbidities, procedure-related variables, and preoperative serum sodium measurements) collected during the South African Surgical Outcomes Study. Data were analysed using recommended statistical methods for unmatched case-control studies.
RESULTS:
The study population comprised 103 patients and 410 controls. Cases were defined as patients who suffered postoperative inpatient mortality, while controls were defined as patients who did not suffer postoperative inpatient mortality. Preoperative hypernatraemia (i.e. a preoperative serum sodium measurement &gt;144 mEq/L) was independently associated with a four-fold higher risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement of 135 - 144 mEq/L (odds ratio (OR) 4.21, 95% confidence interval (CI) 1.19 - 14.83, p=0.025). Preoperative hyponatraemia (i.e. a preoperative serum sodium measurement &lt;135 mEq/L) was not independently associated with a higher or lower risk of postoperative inpatient mortality compared with a normal preoperative serum sodium measurement (OR 1.39, 95% CI 0.70 - 2.76, p=0.346).
CONCLUSIONS:
Preoperative hypernatraemia, but not preoperative hyponatraemia, is a risk factor for postoperative inpatient mortality in SA surgical patients

seems like a very small study and since they include anything under 135 as hyponatremia doesn't seem particularly relevant to patients in the 120s.

 

[nimbus]

just for clarification, we actually do not know if improving the serum sodium improves the risk but it might.

Correct. It might reduce the risk, it might make the outcome worse, or it might make no difference. We don’t know because we don’t have a trial to answer the question. The history of medicine is littered with interventions that seemed to make sense but didn’t help at all or made things worse.

 

[Lawpy]

This is a useful and educational thread, and thanks for linking some studies for further reading 👍

 

[Aether2000]

Another larger study concluding in a multivariate analysis, only severe hypernatremia but not severe hyponatremia resulted in increased post op mortality: https://bjanaesthesia.org/article/S0007-0912(17)30524-X/fulltext

 

[nimbus]

Another larger study concluding in a multivariate analysis, only severe hypernatremia but not severe hyponatremia resulted in increased post op mortality: https://bjanaesthesia.org/article/S0007-0912(17)30524-X/fulltext

Nice reference. These authors suggest using sodium imbalance for risk stratification and advocate more intensive postoperative monitoring for patients with sodium imbalance, not preoperative sodium correction.


“These results have important implications in the perioperative setting. Although from our analysis it is difficult to justify serum sodium correction before surgery, dysnatraemia should be seen as a warning flag or a biomarker for risk of mortality and should prompt investigation for underlying disease processes that may warrant treatment before the commencement of surgery. In practice, our analysis suggests that preoperative serum sodium concentrations could be used to stratify perioperative mortality risk. It is a routine and cheap test, and in practice, behaves as a postoperative mortality biomarker related to the co-morbidity status of surgical patients. Interestingly, although this may seem obvious, our data suggest that clinicians do not use serum sodium in this way. This is apparent when we look at resource utilization. In our study, dysnatraemia was also associated with different resource utilization in terms of ICU admission, use of ventilation, vasoactive drugs, central lines, and cardiac output monitors, but not all patients in the highest risk group used the same level of resources. Patients with moderate and severe hypernatraemia showed an in-hospital mortality in excess of 21%, but only <35% of this group were admitted to an ICU. It is difficult to interpret these results, because there may be many reasons for which high-risk surgical patients are not admitted to a critical care unit after surgery,29 and can be explained partly by different resource availability and practice among the departments that took practice in the study; our results, however, suggest that risk was either not recognized or not acted upon, either for lack of resources or for clinical reasons.”

 

[Noyac]

You can apply this to many lab values. Still we correct severe hyperglycemia before we take the patient to the OR. The thought process, in both cases, beyond worse outcomes, is also muddying of the waters. One wouldn't want the patient to have anything that could create serious periop problems (e.g. altered mental status) that add to the list of differentials.

Sodium also contributes to acid-base balance (see Stewart's strong ion theory), hence hyponatremia = tendency to acidosis. Also, let's not forget how vital it is for all cells (even if it's just 10 mEq/L inside), including cardiac tissue. So I do believe that even just correcting the Na close to the patient's usual baseline decreases the risk for badness. Of course s/he's not "fixed", the same way the diabetic who goes from sugar of 400 to 150 is not either. Many times correcting the Na goes hand in hand with improving the condition that caused it, and the latter can be more important for anesthesia (both in the hypo- and hypervolemic versions).

This type of patient is my bread and butter, and, personally, I can treat him both in the OR and the ICU. But the same way I take a septic shock patient to the OR for source control, I would take a severely hyponatremic one, too, if the benefits clearly exceed the risks.

Hyponatremia - Best Help Ever From Drs. Topf And Weingart With Additional Resources - Tom Wade MD

Note to myself: Here in this post I review hyponatremia. After each resource I’ll go over what I will do in reviewing that resource the next time I visit this page. First I listen to the first thirty minutes of EMCrit … Continue reading →

www.tomwademd.net

Now you are confusing me. 😕
But not really, diabetes “to me” is different. It’s a lack of response to or production of insulin. It does have some serious consequences if left unchecked I’ll agree.
But hyponatremia has many causes. Lets take CHF for example. If you correct the Na you haven’t fixed the CHF, per se’. It’s a low flow or hypoperfusion state still.
obviously, you and I are only scratching the surface here. But I hope my thought process makes sense.