Global Nurses Assistance

Saturday, April 28, 2007

How to calculate drug dosage accurately: advice for nurses ( 1 )

The lack of basic maths skills can be a major problem when it comes to nurses administering drugs to patients. Calculations are still a significant source of drug error.

Parenteral opiates are often relied on to manage acute pain in patients needing effective analgesia. But errors resulting in overdose of intravenous opiate can lead rapidly to respiratory depression. The opiate antagonist naloxone reverses opiate overdose and is usually needed quickly. However, this can cause confusion, because the product is prepared in micrograms. A small volume is involved, and the dose given needs to be titrated against response.

Postoperatively, the epidural route is now common for infusions of opiate and local anaesthetic. If opiates or, indeed, most drugs, have been calculated incorrectly, the consequences for patients can be serious.

If given in too high concentrations, local anaesthetic used in epidural infusions can cause extensive motor blockade, leading to immobility and pressure ulcers, which is distressing to the patient (Lee, 1991). Wheatley et al (2001) call for routine use of pre-filled epidural infusion bags to avoid the risk of calculation error when ward staff prepare infusions.

Nursing competence in drug calculations has been a cause for concern (Duffin, 2000; Coombes, 2000). Hutton (1998a) suggests that a degree of 'de-skilling' has resulted from the increasingly user-friendliness of drug preparations and widespread use of electronic drip counters.

Her research into students' competence in drug calculations demonstrated a marked improvement on initial test results after a structured revision programme.

Written accounts obtained from students in the study revealed that many felt unable to perform calculations such as long division and fractions without using a calculator, as they had come to rely on these at school.

There is some debate over calculator use. Hutton (1998b) argues that calculators are usually available in areas where calculations are complex, and that their use should be encouraged.

The opinion of the United Kingdom Central Council for Nursing, Midwifery and Health Visiting (UKCC) (now the Nursing and Midwifery Council) is that nurses should not rely too heavily on calculators.

The latest guidelines for the administration of medicines (UKCC, 2000) state that the use of calculators 'should not act as a substitute for arithmetical knowledge and skill'.

Developing calculation skills relies on understanding decimals to make conversion easier. And when using long division it is essential to get it the right way round. The use of simple, memorable formulae for regular reference can be a great help .

Drug calculations
Drug calculations appear to be impossibly difficult, unless you break them down into small steps. They are vitally important to get right, yet they are so easy to get wrong. This paper will now look at some commonly used drug calculations and the way that mistakes can happen.

Type A calculations
When the dose you want is not a whole ampoule.

For example:

- Prescription states 200mg (milligrams)

- You have an ampoule of 500mg (milligrams) in 4ml (millilitres).

What volume contains the dose you need?

If you have an ampoule of 500mg in 4ml, and you need 200mg, it can appear to be a daunting calculation. The first step is to find out what volume contains 1mg (4/500) and then multiply it by how many mg you want (200).

The easy way to remember this is the famous nursing equation:

'What you want, over what you've got, times what it's in'

In this instance:

200mg x 4ml / 500mg = 1.6ml

The common error here is to get it upside down, and divide what you've got by what you want. This fortunately gives you a stupid answer, which is obviously wrong, in this case 10ml. You already know that you need a fraction of an ampoule and not two and a bit ampoules, which highlights the error.

To help make sure you get it the right way up, remember WIG:

What you Want x what it's In / What you've Got

Converting units
All weights, volumes and times in any equation must be in the same units. With weights the unit changes every thousand. For example, you need 1000 micrograms (mcg) to make 1 milligram (mg) and 1000 milligrams to make one gram (g) .

Type B calculations
These are infusion rate calculations.

For example:

- Prescription states 30 mg/hour

- You have a bag containing 250mg in 50ml

Therefore, at what rate (ml/hr) do you set the pump?

These are the same as type A calculations, only once you have worked out the volume that contains the amount of drug you need, you set the pump to give that amount per hour.

In this instance, work out how many ml contain ONE mg of drug

Using the WIG equation

30 x 50 / 250 = 6ml

Therefore the calculation shows that, to give 30mg per hour, the infusion pump rate would need to be set at 6ml per hour.

This calculation is straightforward when the rate you want (30mg/hour) and the amount of the drug in the bag (250mg) are both in the same units (mg).

However, if the infusion required that 600 micrograms were to be infused each hour instead, this would first need to be converted into mg before the infusion rate was calculated, that is, 600 micrograms = 0.6mg.

The equation for infusion rate calculation is dose stated in prescription (milligrams per hour) times volume in syringe (in millilitres) divided by the amount in the syringe (in milligrams) equals the infusion rate (millilitres per hour), or:

Dose (mg/hr) x volume in syringe (ml) / Amount in syringe (mg) = Infusion rate

posted by Slamet Widodo Kanapi at 11:02 AM 2 comments

Basic Life Support and AED



The earlier that effective treatment is provided, the more likely it is that a person suffering from cardiopulmonary arrest will survive (RCUK and ERC, 2000).

The interventions that contribute to a successful outcome after cardiopulmonary arrest can be conceptualised as a chain, which has been called the 'chain of survival' (Smith, 2000). The chain is only as strong as its weakest link. Each link must therefore be strong and comprise:

- Recognition of cardiorespiratory arrest

- Early activation of emergency services

- Early basic life support (BLS)

- Early defibrillation

- Early advanced life support (ALS).

Failure of the circulation for three to four minutes will lead to irreversible cerebral damage. BLS acts to slow down the deterioration of the brain and the heart until defibrillation and/or ALS can be provided (RCUK and ERC, 2000). Prompt recognition of cardiopulmonary arrest and prompt instigation of BLS can double the patient's chance of survival (BHF, 2001). Although national guidelines may continue to vary, the underlying scientific principles upon which resuscitation guidelines are based are now international (Winser, 2001).

Health-care professionals in the UK are legally liable for any act or omission on their part that harms such a patient (BMA, 2001; NMC, 2002). The national guidelines indicate health professionals must attend BLS training at least once every 12 months (NHSLA, 2000).

Wherever patients are treated, automated external defibrillation (AED) is a proven effective means for any health-care professional to deliver a defibrillator shock quickly in an emergency (Mancini and Kaye, 1999; Smith, 2000). Use of an AED removes the need for the operator to be able to interpret an electrocardiogram (ECG) trace.

Basic life support procedure
The guidelines (RCUK and ERC, 2000). indicate that a rescuer should:

1. Ensure own safety and that of the patient.

2. Check the patient's responsiveness by gently shaking them and shouting 'Can you hear me?'

3. If there is no response the rescuer should shout for help.

4. Check the patient's mouth and remove any debris and then open the patient's airway using the head-tilt, chin-lift manoeuvre. If cervical spine injury is suspected the jaw-thrust method should be employed.

5. Look, listen and feel for breathing in the patient for 10 seconds.

6. If patient is not breathing call emergency services or hospital cardiac arrest team.

7. Give the patient two rescue breaths with a pocket mask or bag-valve-mask (Jevon, 2002).

8. Check for signs of circulation for 10 seconds. The carotid pulse is located by placing the second and third finger on the patient's trachea - locating the Adam's apple or cricoid cartilage. Move fingers laterally approximately 4-5cm to the sternomastoid muscle mass. Pushing medially you should then be able to locate the carotid artery.

9. If there are no signs of circulation start chest compressions.

10. Continue rescue breathing and chest compressions at a ratio of 2:15 until the emergency services/cardiac team arrive and take over or the patient makes a sign of life.

AED procedure
When an AED is available the RCUK and ERC guidelines (2000) state:

1. Follow BLS steps 1-5

2. If the patient is not breathing call the emergency services or cardiac arrest team and bring the AED to the patient. If the AED is not immediately available start BLS as above.

3. Switch on the AED and attach the electrode pads following spoken or visual directions given by the AED.

4. Ensure that nobody touches the patient while the AED is analysing the rhythm.

5. If a shock is indicated, ensure that everybody is clear of the patient, push the shock button as directed by the AED.

6. Repeat analyse +/- shock, as directed by AED.

7. If there are no signs of circulation after three shocks perform one minute of BLS.

8. Continue to follow AED instructions until advanced life support is available.

If at any time signs of a circulation are present, check for breathing. If breathing is present place the patient in the recovery position and, where possible, give oxygen.

If breathing is absent give rescue breaths at a rate of 10 per minute and then reassess. This action should continue until the emergency services/cardiac arrest team arrive or the patient starts to breathe unaided.

ANATOMY
- The heart lies between the sternum and the spine. External compressions force the sternum down onto the left ventricle, squeezing it between the sternum and the spine and resulting in blood ejection from the heart (RCUK and ERC, 2000; Tortora and Grabowski, 2001)

- Carotid pulse checks are difficult to undertake in patients who have had a cardiorespiratory arrest. These checks are also something not normally performed in everyday practice due to the possibility of undiagnosed thickened carotid arteries - usually due to artherosclerosis. In such cases trying to locate a carotid pulse may result in a small clot breaking off the thickened layer of the artery, resulting in a stroke (RCUK and ERC, 2000; Tortora and Grabowski, 2001)

- The cardiovascular and the respiratory nervous centres are positioned in the medulla oblongata, which is a continuation of the upper portion of the spinal cord. This centre provides the neural control for increasing heart rate and breathing rate. You can expect abnormalities in these functions following a successful resuscitation if the medulla has received a reduced oxygen supply during resuscitation attempts (RCUK and ERC, 2000; Tortora and Grabowski, 2001).

RESUSCITATION
- Successful resuscitation is defined as a return of spontaneous circulation that lasts longer than 20 minutes

- For cardiac compressions, being taught to locate your hands in the centre of the chest (simple method) resulted in greater accuracy of hand placement when compared to the standard method of sliding up the rib cage to the xiphisternum. This resulted in less delay between ventilation and resuming chest compressions

- Effectiveness declines in cardiac compressions after one minute. A study has demonstrated that one minute of compressions followed by two minutes rest (a three-person compression team) was significantly better than a two-person team with only one minute's rest in between each cycle of BLS.

(RCUK, 2000c)

posted by Slamet Widodo Kanapi at 10:04 AM 1 comments

Nurses in Kuwait

BSN FC Kuwait


Anda bisa sukses sekalipun tak ada
orang yang percaya Anda bisa. Tapi Anda
tak pernah akan sukses jika tidak percaya pada diri sendiri.
-. William J.H. Boetcker .-
posted by Slamet Widodo Kanapi at 4:46 AM 0 comments