Hyponatremia is the most common electrolyte imbalance found in clinical practice, affecting approximately 1.72 percent of the US population. The condition refers to a low concentration of sodium in the blood, falling below 135 mmol/l. Hypernatremia – the opposite condition to hyponatremia – is associated with high sodium levels, exceeding 145 mmol/l.
Hyponatremia is often found in patients with multiple co-morbidities, such as diseases that impact the vital organs. This makes it more common in elderly people and hospitalised patients; in fact, hyponatremia affects up to 30 percent of patients in hospital and is associated with increased morbidity and mortality. The condition has been reported to delay surgery, prolong post-surgical recovery, and increase hospital readmissions.
A serious condition
As well as long term health conditions, hyponatremia and hypernatremia can be triggered by excessive consumption of water or dehydration respectively. Both conditions can also be caused by changes in medication that cause the retention of, or expulsion of liquid. Mild versions of hyponatremia can cause confusion or sluggishness, irritability, restlessness or nausea. More severe cases can lead to vomiting and seizures. The condition can ultimately cause an altered mental state, seizures, a coma or death.
Interfering with surgery
Hypernatremia is associated with increased risk of venous thromboembolisms (VTEs) – life-threatening blood clots, typically in the deep veins of the leg, that can lead to a pulmonary embolism. VTE risk increases up to 100-fold in hospitalised patients compared to the general population: it is the leading cause of death and disability in hospital. Elderly and critically ill patients undergoing surgery are already at risk of developing VTE due to a lack of mobility during recovery; those with high sodium levels are at an even higher exposure.
The risk of in hospital VTE increases with age, particularly among those older than 65. Around one third of adults older than 65 and half of those older than 80 will fall at least once every year. Falls can cause fractures and breaks in older, more brittle bones. According to a study by Bergh et al entitled ‘Fracture incidence in adults in relation to age and gender: A study of 27,169 fractures in the Swedish Fracture Register in a well-defined catchment area,’ the mean age for fragility fractures was above 63 years (both genders combined). Hip fractures are especially common among the elderly with more than 95 percent of hip fractures caused by falling.
Surgery is the preferred treatment option for most fractures, and the National Institute for Health and Care Excellence (NICE) recommends that surgical intervention occurs within 48 hours of admission to hospital with a fracture. Patients must have stabilised sodium levels for surgery to proceed and it may need to be delayed if the patient displays symptoms of a sodium imbalance.
Identifying the risks
As well as potentially leading to delays in surgery, immobile patients become increasingly at risk of VTE as they wait for the appropriate sodium levels to be achieved. Healthcare professionals monitor patient sodium levels to avoid such complications and active interventions are possible to help patients reach a sodium balance. But this process cannot be rushed. The NHS states that: “inappropriately rapid correction of hyponatraemia can cause osmotic demyelination which can result in permanent neurological deficits and even death”. However, during this stabilisation process patients largely remain immobile in hospital, increasing the risk of VTE.
Additionally, sodium imbalances can also increase the risk of complications and death in the 30 days following a procedure. A population-based retrospective cohort study by Temraz et al. (2018) evaluated the association between sodium imbalances and the incidence of VTE and other selected perioperative outcomes. The study, which looked at patients in the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) database, found that both hyponatremia and hypernatremia were significantly and independently associated with post-surgical VTE and a significant contributor to the need for patients to return to operation rooms.
Enhancing standard of care
When drug prophylaxis cannot be prescribed, VTE prevention standard of care is intermittent pneumatic compression (IPC) – a boot-like cuff that compresses the leg to increase blood flow. IPC, however, is not suitable for all patients due to fragile skin or complex limb injury – representing a significant unmet need and requirement for an alternative mechanical intervention. Fortunately, innovation in healthcare is introducing new systems of care that are helping healthcare professionals identify risk factors sooner and treat and prevent life-threatening conditions quicker.
Innovation in MedTech
MedTech is one of the forces driving this transformation around how care is provided. Unlike pharmaceutical interventions, MedTech solutions can be applied to address multiple different conditions and offer improved outcomes for those with no other alternative.
Examples of successful MedTech applications include hardware and software that unobtrusively monitors patient wellbeing to provide doctors and nurses with alerts that inform them of patients’ vital signs. In theory, this could be extended to enable healthcare professionals to address risks such as sodium imbalances or the development of VTE. Additionally, devices are now commercially available that address the unmet need of patients that cannot tolerate IPC. Wearable devices – such as the geko™ device – that promote blood flow in the deep veins of the legs offer an alternative prophylaxis and can therefore be used pre- and post-surgery to reduce VTE risk. Patients identified with sodium imbalances can be prescribed such devices perioperatively to reduce the risk of VTE developing.
Given the interaction between VTE and sodium imbalances, it is possible for the presence of one to indicate the risk of another. Temraz et al suggests that sodium levels could provide a relevant early warning signal to identify patients at risk of developing VTE. Because sodium levels are frequently measured in hospitalised patients – not solely those awaiting or recovering from surgery – this could be helpful in assessing VTE risk. An improvement in serum sodium in patients with hyponatremia could arguably reduce mortality rates from VTE.
Adopting MedTech to reduce risk factors
As Temraz et al. conclude, sodium imbalances in surgical patients is a significant issue that should not be ignored. Not only can sodium imbalances delay surgery and lead to life-threatening conditions, but because they can indicate an increased risk of other severe, yet preventable, conditions like VTE.
A major challenge facing the future of healthcare delivery is finding ways to embrace innovation quickly to enable healthcare professionals to better identify hospital-induced conditions, particularly for patients suffering with co-morbidities and at a higher risk of developing complications in hospital.