Vancouver IM LMR

Here are the notes from this Halloween’s journal club on a very spooky complication of hyponatremia – osmotic demyelination syndrome

Some takeaways:

1. ODS is a rare complication in hyponatremia. There are multiple risk factors that make individuals more vulnerable to developing ODS – hypokalemia, alcohol use, malnutrition, liver disease, as well as low initial sodium <120 and previous observational studies supporting rapid correction >8-10/24 hours as a risk factor. To avoid this, locally we have generally followed correction targets of ~<8mmol/L in 24 hours, and as low as 4-6mmol/L in 24 hours for those at higher risk. Re-lowering sodium to avoid overcorrection involves frequent labs, IV infusions and the consequent exposure to issues around med error and failures in MD-MD/RN-RN handover.
2. Cohort studies are a observational method that can only provide correlational data, and cannot imply causality or lack of causality. Many limitations of this study revolve around availability of data and what can feasibly be collected in retrospect from medical records. This does result in issues with possible contamination of the sample with acute hyponatremia (which would have much lower risk for ODS with rapid correction), as well as likely significant ODS case-finding issues.
3. This study supports the idea that ODS is rare and that risk increases with lower initial sodium < 120 and especially < 110. An interesting finding was that some ODS happened with sodium over 120 which is not thought to be a higher risk group, but due to the low event rate for ODS in this study we aren’t able to know about the presence of additional risk factors in these patients. Overall I am not sure this study can convincingly say that ODS is not related to sodium overcorrection, and the data does not strongly support us withdrawing safeguards, especially for patients with ODS risk factors and those with lower Na < 120.