Last week, the Australian Therapeutic Goods Administration added intravenous (IV) fluids to the growing list of medicines in short supply. The shortage is due to higher-than-expected demand and manufacturing issues.

Two particular IV fluids are affected: saline and compound sodium lactate (also called Hartmann’s solution). Both fluids are made with salts.

There are IV fluids that use other components, such as sugar, rather than salt. But instead of switching patients to those fluids, the government has chosen to approve salt-based solutions by other overseas brands.

So why do IV fluids contain different chemicals? And why can’t they just be interchanged when one runs low?

We can’t just inject water into a vein

Drugs are always injected into veins in a water-based solution. But we can’t do this with pure water, we need to add other chemicals. That’s because of a scientific principle called osmosis.

Osmosis occurs when water moves rapidly in and out of the cells in the blood stream, in response to changes to the concentration of chemicals dissolved in the blood plasma. Think salts, sugars, nutrients, drugs and proteins.

Too high a concentration of chemicals and protein in your blood stream leads it to being in a “hypertonic” state, which causes your blood cells to shrink. Not enough chemicals and proteins in your blood stream causes your blood cells to expand. Just the right amount is called “isotonic”.

Mixing the drug with the right amount of chemicals, via an injection or infusion, ensures the concentration inside the syringe or IV bag remains close to isotonic.

What are the different types of IV fluids?

There are a range of IV fluids available to administer drugs. The two most popular are:

• 0.9% saline, which is an isotonic solution of table salt. This is one of the IV fluids in short supply
• a 5% solution of the sugar glucose/dextrose. This fluid is not in short supply.

There are also IV fluids that combine both saline and glucose, and IV fluids that have other salts:

• Ringer’s solution is an IV fluid which has sodium, potassium and calcium salts
• Plasma-Lyte has different sodium salts, as well as magnesium
• Hartmann’s solution (compound sodium lactate) contains a range of different salts. It is generally used to treat a condition called metabolic acidosis, where patients have increased acid in their blood stream. This is in short supply.

What if you use the wrong solution?

Some drugs are only stable in specific IV fluids, for instance, only in salt-based IV fluids or only in glucose.

Putting a drug into the wrong IV fluid can potentially cause the drug to “crash out” of the solution, meaning patients won’t get the full dose.

Or it could cause the drug to decompose: not only will it not work, but it could also cause serious side effects.

An example of where a drug can be transformed into something toxic is the cancer chemotherapy drug cisplatin. When administered in saline it is safe, but administration in pure glucose can cause life-threatening damage to a patients’ kidneys.

What can hospitals use instead?

The IV fluids in short supply are saline and Hartmann’s solution. They are provided by three approved Australian suppliers: Baxter Healthcare, B.Braun and Fresenius Kabi.

The government’s solution to this is to approve multiple overseas-registered alternative saline brands, which they are allowed to do under current legislation without it going through the normal Australian quality checks and approval process. They will have received approval in their country of manufacture.

The government is taking this approach because it may not be effective or safe to formulate medicines that are meant to be in saline into different IV fluids. And we don’t have sufficient capacity to manufacture saline IV fluids here in Australia.

The Australian Society of Hospital Pharmacists provides guidance to other health staff about what drugs have to go with which IV fluids in their Australian Injectable Drugs Handbook. If there is a shortage of saline or Hartmann’s solution, and shipments of other overseas brands have not arrived, this guidance can be used to select another appropriate IV fluid.

Why don’t we make it locally?

The current shortage of IV fluids is just another example of the problems Australia faces when it is almost completely reliant on its critical medicines from overseas manufacturers.

Fortunately, we have workarounds to address the current shortage. But Australia is likely to face ongoing shortages, not only for IV fluids but for any medicines that we rely on overseas manufacturers to produce. Shortages like this put Australian lives at risk.

In the past both myself, and others, have called for the federal government to develop or back the development of medicines manufacturing in Australia. This could involve manufacturing off-patent medicines with an emphasis on those medicines most used in Australia.

Not only would this create stable, high technology jobs in Australia, it would also contribute to our economy and make us less susceptible to future global drug supply problems.

Nial Wheate, Professor and Director Academic Excellence, Macquarie University and Shoohb Alassadi, Casual academic, pharmaceutical sciences, University of Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.

So you’ve got yourself a gym membership or bought a set of home weights. Now what? With the sheer amount of confusing exercise advice out there, it can be hard to decide what to include in a weights routine.

It can help to know there are broadly two types of movements in resistance training (lifting weights): compound exercises and isolation exercises.

So what’s the difference? And what’s all this got to do with strength, speed and healthy ageing?

What’s the difference?

Compound exercises involve multiple joints and muscle groups working together.

In a push up, for example, your shoulder and elbow joints are moving together. This targets the muscles in the chest, shoulder and triceps.

When you do a squat, you’re using your thigh and butt muscles, your back, and even the muscles in your core.

It can help to think about compound movements by grouping them by primary movement patterns.

For example, some lower body compound exercises follow a “squat pattern”. Examples include bodyweight squats, weighted squats, lunges and split squats.

We also have “hinge patterns”, where you hinge from a point on your body (such as the hips). Examples include deadlifts, hip thrusts and kettle bell swings.

Upper body compounded exercises can be grouped into “push patterns” (such as vertical barbell lifts) or “pull patterns” (such as weighted rows, chin ups or lat pull downs, which is where you use a pulley system machine to lift weights by pulling a bar downwards).

In contrast, isolation exercises are movements that occur at a single joint.

For instance, bicep curls only require movement at the elbow joint and work your bicep muscles. Tricep extensions and lateral raises are other examples of isolation exercises.

Compound exercises can make daily life easier

Many compound exercises mimic movements we do every day.

Hinge patterns mimic picking something off the floor. A vertical press mimics putting a heavy box on a high shelf. A squat mimics standing up from the couch or getting on and off the toilet.

That might sound ridiculous to a young, fit person (“why would I need to practise getting on and off a toilet?”).

Unfortunately, we lose strength and muscle mass as we age. Men lose about 5% of their muscle mass per decade, while for women the figure is about 4% per decade.

When this decline begins can vary widely. However, approximately 30% of an adult’s peak muscle mass is lost by the time they are 80.

The good news is resistance training can counteract these age-related changes in muscle size and strength.

So building strength through compound exercise movements may help make daily life feel a bit easier. In fact, our ability to perform compound movements are a good indicator how well we can function as we age.

What about strength and athletic ability?

Compound exercises use multiple joints, so you can generally lift heavier weights than you could with isolation exercises. Lifting a heavier weight means you can build muscle strength more efficiently.

One study divided a group of 36 people into two. Three times a week, one group performed isolation exercises, while the other group did compound exercises.

After eight weeks, both groups had lost fat. But the compound exercises group saw much better results on measures of cardiovascular fitness, bench press strength, knee extension strength, and squat strength.

If you play a sport, compound movements can also help boost athletic ability.

Squat patterns require your hip, knee, and ankle to extend at the same time (also known as triple extension).

Our bodies use this triple extension trick when we run, sprint, jump or change direction quickly. In fact, research has found squat strength is strongly linked to being able to sprint faster and jump higher.

Isolation exercises are still good

What if you’re unable to do compound movements, or you just don’t want to?

Don’t worry, you’ll still build strength and muscle with isolation exercises.

Isolation exercises are also typically easier to learn as there is no skill required. They are an easy and low risk way to add extra exercise at the end of the workout, where you might otherwise be too tired to do more compound exercises safely and with correct form.

In fact, both isolation and compound exercises seem to be equally effective in helping us lose body fat and increase fat-free muscle mass when total intensity and volume of exercises are otherwise equal.

Some people also do isolation exercises when they want to build up a particular muscle group for a certain sport or for a bodybuilding competition, for example.

I just want a time efficient workout

Considering the above factors, you could consider prioritising compound exercises if you’re:

• time poor
• keen to lift heavier weights
• looking for an efficient way to train many muscles in the one workout
• interested in healthy ageing.

That said, most well designed workout programs will include both compound and isolation movements.

Correction: This article has been amended to reflect the fact a weighted row is a pull pattern, not a push pattern.

Mandy Hagstrom, Senior Lecturer, Exercise Physiology. School of Health Sciences, UNSW Sydney and Anurag Pandit, PhD Candidate in Exercise Physiology, UNSW Sydney

This article is republished from The Conversation under a Creative Commons license. Read the original article.