Health Forum

Hospital Pantai Ayer Keroh Melaka

Date: 6-3-2010 (Saturday)

Time: 1.30pm

Venue: Conference Room, 3rd Floor, Melaka Mall
(Opposite Jaya Jusco, Ayer Keroh)

Protect your Kidneys, Control Diabetes

by 

Dr Chow Yok Wai

Consultant Nephrologist & Physician

(3 CPD points for All Registered Nurses)

Admission FREE

Calcium vs Corrected Calcium (BM Translation)

Apa itu “Corrected Calcium”

Terjemahan olih En Soong Chong Seng

Kita biasa melihat Calcium dan Corrected Calcium didalam laporan makmal keputusan kajian darah. Calcium adalah sejenis garam galian yang terbanyak bilangannya didalam badan di mana 99% di dalam tulang dalam bentuk calcium phosphate (garam). 22.5mmol daripada Calcium terdapat di luar sel dan 9mmol daripadanya terdapat di dalam serum.

Sr Calcium yang sentiasa di kawal dan mempunyai kandungan normal dalam lingkungan sekitar 2.2-2.9 mmol. Tahap jumlah Calcium adalah berkait rapat dengan tahap kandungan albumin dalam badan.
Semasa mengalami kegagalan buah pinggang, tahap albumin biasanya rendah. Oleh yang demikian, bacaan sr Calcium tersebut tidak menggambarkan tahap kadar sr Calcium yang sebenarnya.

Oleh yang demikian, untuk mengukur tahap sr Calcium dengan lebih tepat, kita perlu mengukur free(ionized) Calcium di mana ia tidak jauh berbeza dengan tahap kandungan albumin. Kandungan normal ionized calcium ialah dalam lingkungan1.1-1.4mmol. Jadi, tahap “corrected Calcium” dapat dikira di dalam pesakit yang mengalami kerosakan buah pinggang dengan nilai yang mewakili kandungan tahap Calcium di dalam badan dengan lebih tepat.Tahap “corrected Calcium “ mengambil kira tahap abnormal kandungan albumin dalam badan dan membuat sedikit pengubahan tahap kandungan Calcium melalui andaian bahawa tahap kandungan albumin yang normal. Formula untuk mengira “corrected Calcium”:

Corrected Calcium(mmol/L) = measured total Ca(mmmol/L) + 0.02(40- serum albumin(g/L).
1) 40 mewakili purata tahap albumin dalam g/L
2) Setiap 1g/L pengurangan kandungan albumin akan meningkatkan 0.02 mmol/L dalam sr Ca.

Dalam kes hypoalbuminemia, tahap “corrected Calcium” adalah lebih tinggi daripada jumlah Calcium yang sebenarnya. Perlu ambil perhatian bahawa jika tahap albumin melebihi 40g/L, maka bacaan“corrected Calcium” adalah lebih rendah.

Garispanduan KDOQ menetapkan bahawa nilai "lower limit" adalah 1.13 mmol/L dan "upper limit" ialah 1.78 mmol/L

Arterial & Venous Pressure Monitoring..(Part 1)

Arterial and Venous Pressure monitoring….

When we look at a Haemodialysis (HD) machine, we can see 2 ports where the pressure monitoring lines of the bloodline sets via transducer protectors are attached to. One is for monitoring the arterial pressure and the other for monitoring venous pressure within the extra-corporeal blood circuit.

The purpose of having the device to monitor the pressure within the bloodlines is to ensure the smooth flow of the extra-corporeal blood by detecting any pressure built-up within the circuit. Preemptive measures can be taken long before a problem can arise by just monitoring the pressure trend.

Many Haemodialysis Centres (HDCs) has found it fit to do away either with the arterial or both the arterial and venous pressure monitoring. Some staff and patients’ themselves find the alarm triggered by the arterial and venous pressure monitoring very annoying. The slightest movement of the patient’s limb to which the AVF needles are placed can trigger the alarm.

However without them, we would not be forewarned of any impending problem arising from the pressure built-up. These safety measures are in place for a very specific purpose, patient’s safety therefore they should not be arbitrarily omitted.

Calcium vs Corrected Calcium

What is the difference between Calcium and Corrected Calcium?

In our patients’ laboratory analysis printout we normally will see Calcium and Corrected Calcium values stated. So what is Calcium and Corrected Calcium…...?

Calcium is a mineral found in the largest quantity in the body and 99% is in the bones as calcium phosphate (salt). A total of 22.5 mmol of Calcium is found extra-cellular and of this 9 mmol is found in the serum.

Serum Calcium is closely regulated with normal range of Calcium (extra-cellular) of 2.2 – 2.9 mmol. The level of Serum Calcium is associated with the level of Serum Albumin. Calcium has an affinity to Albumin.

As in Chronic Kidney Disease (CKD), the Serum Albumin level is usually lower and therefore affects the reading of the Serum Calcium and does not reflect the actual Serum Calcium level.

Therefore to accurately measure the level of Serum Calcium we need to measure the free (ionized) Calcium. Ionized Calcium does not vary with the Albumin level. The normal range of ionized Calcium level is 1.1 – 1.4 mmol.

A corrected Calcium level can be calculated in situations such as CKD to present an actual representation of Calcium level in the body.

Corrected Calcium takes into consideration the abnormal level of Albumin and makes adjustment to the Calcium level as though the Albumin level is normal.

Corrected Calcium (mmol/L) =

measured total Ca (mmol/L) + 0.02 (40 - Serum Albumin [g/L]),

where 40 represents the average Albumin level in g/L

each 1 g/L decrease of Albumin, will raise 0.02 mmol/L in serum Ca

In cases of hyperalbuminemia, the level of Corrected Calcium is lower than the total Calcium.

Wishing
All Malaysian

"A HAPPY AND PROSPEROUS 
CHINESE NEW YEAR"

Best Wishes & Warmest Regards...

MalaysianKidneySPA

Blunt AVF needle....the final part

How is it done.....?

1.   First assess the AVF and identify the directional flow of the AVF.
2.   Select the appropriate sites for the arterial (supply) and venous (return).
3.   It is pertinent to stress that cleanliness is of utmost importance in establishing a tract for and using blunt AVF needles.
4.   Clean the intended area with "Providone Iodine" or any other suitable disinfectant. Remove any scabs from previous cannulations if any. Please use aseptic technique and a pair of tweezers, NOT the tip of a      needle.
5.   Either using the 3 fingers or 2 fingers technique, secure the vessel for cannulation.
6.   Aim the tip of the sharp AVF needle for the center of the vessel at 25 - 35o and proceed with the cannulation.
7.   Once blood rushes into the syringe, level the AVF needle and glide it along the center of the vessel.
8.   Secure the AVF needle and flush it with the Normal Saline in the syringe to check for good blood flow.
9.   This procedure is repeated exactly the same, the next 8 - 10 cannulations. Same spot, same hole, same
      angle and same depth by the same cannulator.
10. During the next cannulation, soak the scab that has formed at the opening of the cannulation site with Normal Saline and slowly peel it away with a clean pair of tweezers and NOT the tip of a needle.
11. After a number of cannulation, a hole will apear underneath the scab.
12. Do not allow patient to remove the scab him/herself.
13. Thereafter cannulation through the hole will require less effort than before the site matures.
14. When the cannulator is satisfied the tract has been formed and is matured, can he/she starts to use the
blunt AVF needle for cannulation.
15. When he or she is confident that other treatment practitioner can cannulate successfully the buttonhole with a blunt AVF needle can then others cannulate the patient.


What's next.....?

1. Do not use a sharp AVF needle on a mature site as it can injure the tract.
2. Do not use too much force when cannulating with a blunt AVF needle.
3. If bleeding occurs around the blunt AVF needle, it means that the tract is stretched or scarring has occurred.
4. If you are unable to insert the blunt AVF needle into the vessel, push the vessel to the vessel and gently lift the tip of the needle.The flap of the vessel may be misaligned with the tract.
5. If this does not work, then use a sharp AVF needle for the next couple of cannulations. Ensure that you stay in the tract so as not to injure or scar the tract. This will help in refashion the flap of the vessel.
6. What if the tract does not take form, not to worry. Select a new site and create a new tract.

Obstructions to a successful creation of a tract.....

1. Badly scarred vessel due to cannulation problems.
2. Thick subcutaneous layer.
3. One too many cannulators on the same patient.
4. Stenosis present at the chosen site.

Benefits.....

1.   Patients enjoy less painful cannulations.
2.   Patients can self cannulate.
3.   Patients experience less stress during cannulations.
4.   Less cannulation complications.
5.   Less mistreatment or reschedule treatments.
6.   Fewer hospitalizations due to cannulations or AVF complications.
7.   Longer AVF survival.

8.   Faster cannulations.
9.   Less stress on treatment practioners due to problematic cannulations.
10. Increased safety with less stick injuries.

The cost of a blunt AVF needle....?

Presently the cost is higher than a sharp AVF needle but nevertheless it is worthwhile to consider it and prices will comedown when demand for it increases.......

Are you game for it......talk to your patients.......explore the posibilities.....

Blunt AVF Needling....(Part 5)

What is a "Blunt AVF Needle"?

It is what the term "blunt AVF needle" implied..... an AVF needle that is blunt...

Sample of a sharp AVF needle

Sample of a blunt AVF needle

Pictures from:  http://www.nipro-europe.com/Biohole.asp



So how does one cannulate without a cutting edge.......?  So continue reading.......


 The "Blunt AVF Needling"

Who can blunt AVF needling be carried out on....? Anyone with a native AVF and not one with an artificial graft can undergo blunt AVF needling. Patient should have a satisfactory level of personal hygiene.

What is a "tract"

The tract is a passage from the outer skin to the vessel.This tract is formed when repeated cannulations are carried out over and over again. After sometime, the injuries of the inner surface of the tract is minimised and the tract is formed. This tract is similar to the tract of a earring tract.

Who can create a tract.....

The "Cannulator"

A cannulator is an experienced trained treatment practitioner whom has the consistency and ability to cannulate successfully any AVF. Once the cannulaor has been identified, he/she is give that task to create the tract on a patient for blunt AVF needling.

The cannulator is THE person whom shall cannulate the selected patient each and every time while the tract is being developed. The cannulator needs to cannulate at the same spot, same angle and same depth every time when the patient comes for treatment for the next 8-10 treatment (more if patients are poor healers).

The "Site"

A clean site for each arterial and venous cannulation points are selected which is straight, level and with a vessel prominently visible with no scars or aneurysm is chosen.

Initially a sharp AVF needle of 17G is recommended to cannulate the patient when the tract is being created.

During this crucial period, no one other than the cannulator can cannulate the patient. Should he/she is not available or when an infiltration has occurred than cannulate away (preferable more than 1 inch) from the intended sites.

to be contd......

Blunt AVF Needles.....(Part 4)

Blunt AVF needling......

The ArterioVenous Fistula (AVF) has been the "lifeline" for haemodialysis treatment modality. The use of AVF is the Gold Standard for blood access in chronic haemodialysis.The use of sharp AVF needles have been the only needles known to haemodialysis widely used.

Over the years, the needs to explore other less painful and traumatised methods of cannulation were overwhelming. Countless complications and damages to the AVF and patients are due to inexperience, abuse and the indifferent attitude shown by the treatment practitioners are abound. The ignorance, lack of knowledge and interest by the patients themselves too share part of the blame. 

Efforts were made in the West and Japan to find better solutions to avoid AVF complications such anuerysms, stenosis, infiltrations and host of many others which have resulted shorter than expected lifespan of AVF and unnecessry avoidable hospitalisations of patients.

Blunt AVF needles has been in used in the West and Japan for over 25 years with much success. It is high time that we too explore this method of cannulation and give it due consideration.

Patients using blunt AVF needles had indicated that the procedure is practically painless than that of sharp AVF needles. This too has reduced the extreme cannulation stress experienced by patients with cannulation problems.

Besides reduced incidences of patients having missed haemodialysis treatment due to complications of cannulation problems, less hospitalisation and a longer lifespan of the AVF, the treatment practitioners experienced a faster cannulation time, less stress due to poor cannulations, less possibility of stick injuries and higher satisfaction of succesful cannulation.

So what is "blunt AVF needle"........

to be contd.......

The practice now.....(Part 3)

AVF aneurysm occurs when repeated cannulation in a same general area and can also be due to back pressure from a stenosis occurring just beyond the aneurysm.

Try avoiding cannulating from the side of the vessel or turning your hand when cannulating as this will cause cutting the vessel from the side and can cause side infiltration.

The vessel intended to be cannulated is restrained and this will cause the vessel to be engorged. After identifying the spot to be cannulated, used fingers of the less dominate hand to secure the vessel and use the middle finger holding the AVF needle to taut (pull) the skin of the AVF while inserting the needle.

Another method of hand placement is to use the thumb of the less dominate hand to compress the distal part of the vessel to be cannulated. The index finger is use to tout the skin area near the cannulation site. The dominate hand is to hold the needle. As for the venous AVF needle, the index finger of the less dominate hand is use to compress the distal part of the vessel while the thumb is use to tout the skin area near the cannulation site.

Ensure that your AVF needle is attached to a syringe half filled with either Normal Saline or Heparinised Saline. Open the clamp of the AVF needle, slowly but surely advance the needle to the center of the vein. When the AVF needle enter the vessel a gush of blood can be seen entering the syringe.

Level the AVF needle and advance the needle into the center of the vessel. Anchor the AVF needle securely with surgical tape. Release any restrain used in the procedure immediately. Flush the syringe to check for good blood flow in the AVF needle. Observed for any infiltration if any.

After both needles are in and secured, you are ready to start the treatment proper.....

The practice now....(Part 2)

After receiving the the attending Nephrologist/Physician permission to proceed with the first cannulation, identity the most experienced treatment practitioner whom has the best success rate of first time cannulation of new AVF to undertake the task.

The use of some form of restrain or tourniquet to sufficiently and uniformly engorged the intended vessel to be cannulated but NEVER over do it as we do not want unnecessary infiltration (swelling) to occur if something was to go wrong.

If the patient has a catheter in placed, then cannulate the arterial needle only and use the catheter as the "return". With only the AVF needle in place, if an infiltration occurs the resultant hematoma will be minimised.

Secondly, monitoring of the pre-pump arterial pressure can be done to correctly determine if the AVF has a good arterial flow. An pre-pump arterial pressure of (-) 250mmhg at a blood pump speed of 200ml/min via a 17G needle is good. A higher (-) pressure reading indicates the AVF supply flow to be insufficient and not good.

Next check the flow direction of the AVF; identify the incision or the anastomosis site of the AVF. Then palpate the AVF, find the access midpoint and compress lightly with a finger. The vessel with the arterial inflow will be engorged and pulsating with the flow, whereas the vessel for the outflow will diminished or not pulsating.

Another method is to auscultate; again use a finger to compress gently the AVF access midpoint, then with the aid of a stethoscope auscultate for the vessel of the arterial inflow and you can hear the pulsating flow of the arterial blood. As for the outflow vessel, you will hear a diminised blood flow with no pulsation.

Next compare the proposed AVF needle with the intended vessel to be cannulated with and without the vessel being constrained. Ensure the size of the AVF needle is appropriate for the intended vessel. Below is the guideline for size of AVF needles and the blood flow it can support:

       17G needle = 200-250ml/min
       16G needle = 250-350ml/min
       15G needle = 350-450ml/min
       14G needle = >450ml/min


Monitor the pre-pump arterial pressure, it should not be excessively higher of  more than (-) 250mmgh as this will indicate the AVF cannot support the blood pump speed.

Never underestimate the need to inform and explain to the patient the procedure and what to expect.

The AVF needle placement; the arterial AVF needle is cannulated either against the arterial inflow or along the blood outflow. The arterial AVF needle placement should be at least 1.5 inch from the anastomosis site. The arterial and venous AVF needle should be at least 1.5 inch apart.The venous AVF needle placement is always along the blood outflow.

Always try to locate an area where the vessels intended are straight and not torturous as this will lead to infiltrations and complications. Other no go areas are aneurysm and thinned-out areas....

to be contd......

Congratulations...

CONGRATULATIONS!!!

Dr Chow Yok Wai

MD (USM) MRCP (UK) AM (Mal)

Consultant Nephrologist & Physician

on the commencement of your private practice

at

Pantai Ayer Keroh Hospital

Melaka

Best Wishes and Warmest Regards 

MalaysianKidneySPA