Peripheral venous cannula introducing technique, number of attempts required and association with spreading MRSA

Dr Kadiyali M Srivatsa

INTRODUCTION

Initially reported among injecting drug users in Detroit in 1981 and then associated with the

deaths of 4 children in Minnesota and North Dakota in 1997. Community-associated

methicillin-resistant Staphylococcus aureus (MRSA) has become the most frequent cause

of skin and soft tissue infections presenting to emergency departments in the United States

(1). Some paper quotes 74% of organisms present in the skin to be Staph aureus.

The most commonly used device in the forearm and hands are the short peripheral venous

cannula. Due to its relatively short duration of use, it is said be rarely associated with blood

stream infection (Gantz et al 1984; Maki and Ringer 1991; Ena et al 1992). Phlebitis is the

most important complication associated with peripheral venous cannulas, and is largely a

physiochemical or mechanical, rather than an infectious, phenomenon. Risk factors for the

development of phlebitis include type of infuscate, cannula material, size, and host factors.

When phlebitis does occur, the risk of local cannula-related infection may also increase

(Gantz et al 1984; Larson and Hargiss 1984; Hoffman et al 1988). The pathogenesis of

cannula-related infections is complex but most appear to result from skin organisms at the

cannula insertion site migrating into the cannula track, eventually colonising the cannula tip

(Snydman et al 1982; Cooper and Hopkins 1985). Contamination of the cannula hub may

also be an important contributor to the colonisation of cannula lumens (Linares et al 1985;

Radd et al 1993; Salzman et al 1993). Hand washing and aseptic technique are the major

preventive strategies for cannula-related infections.

Insertion of a peripheral venous cannula is a common, although painful, procedure

performed by every doctor. Intravenous cannula – as well as the word ‘Venfon@ - is hated

by all, especially patients and house officers (2). Though it is an operation performed many

times each day, and one that every doctor will perform countless times in the span of his

career, it can nevertheless be a daunting experience. The procedure requires very fine

hand control and considerable practice. As junior doctors accept 60% success rate to insert

cannula in the first attempt and about 90% as experienced seniors.

It is widely accepted that among hospitalised patients, central venous catheters pose a

greater risk for than do peripheral vascular catheters (3) although largely preventable,

vascular catheter related bloodstream infections are frequent and potentially serious

infections among hospitalised patients (4). Bacteraemia due to vascular catheters prolongs

hospital stay and increases both healthcare costs and morbidity and mortality rates,

particularly when caused by invasive pathogens such as Staphylococcus aureus (5, 6).

However, the enormous number of peripheral venous cannula currently used in clinical

practice may result in an increasing number of cannula-related complications such as

phlebitis, thrombosis, bacteraemia (7) and invasive MRSA infections

Among patients with peripheral venous cannula blood stream infection, catheters inserted in

the emergency department had a significantly shorter duration in situ compared with those

inserted on hospital wards. Patients with peripheral venous cannula blood stream infection

caused by S. aureus had a higher rate of complicated bacteraemia (8).

Bloodstream infections remain underestimated and potentially serious complications of peri-

pheral vascular cannula. Targeted interventions should be introduced to minimise this com-

plication by identifying the number of attempts & duration required. We could not find any lit-

erature to define adequate skin preparation required to make the are sterile before punctur-

ing the skin.

This method has been used by three generations of doctors. However it has not yet been

properly evaluated. Most of us assume that the technique is safe and therefore continue to

puncture veins, despite having experienced the frustration of failure and sadness of inflict-

ing pain to the child (2). Some doctors learn to accept failure, others blame the vein but not

many have assessed their own technique.

Most studies look into various types of cannula, associated infections and pain relief. Dis-

cussions regarding cannulation are restricted to blood flow through the cannulae, risk

factors and prevention of contamination, but not much has been written regarding the actual

technique of inserting peripheral lines. We could not find any study which compares suc-

cess rates, time taken, reason for failure and the number of attempts required to success-

fully cannulate a vein and adequate skin preparation required prior to insertion to prevent

infection. This strict aseptic technique is often ignored when the doctors and nurses fail to

introduce cannula in the first attempt. This factor is likely to result in introducing spreading

antibiotic resistant organisms. Mastering this technique takes years, yet we fail at times of

great urgency, but struggle repeatedly and we may succeed due to perseverance.

Observational Study

An observational study of cannulation a vein was conducted in the Paediatric unit of a

district general hospital in UK . The aim of this study was to identify the number of attempts,

the duration required and to compare the success rate of cannulating a vein by senior and

Junior Resident doctors. Cannulating veins of seventy-three babies (1.6+/-2.6 months) were

observed. The number of attempts required to successfully cannulate a vein was 2.48 +/-

1.58 and the time taken was 21+/-0.14 minutes.

One hundred and seventy seven (n=177) cannulae were used to successfully cannulate

seventy three (n=73) children but (104) 58.7% discarded due to failed cannulation . Doctors

used three (1 - 9) cannulae to successfully cannulate one vein. Success rate of cannulating

a vein in the first attempt by senior doctor was 9/22 (49.3%) and the Junior Resident doctor

success was 5/40 (12.5%). Doctors successfully cannulated a vein without a double

puncture in 10/73 (13.7%) and failed to cannulate a vein after locating (puncturing) a vein in

27/73 (34.2%). Senior doctors repositioned cannulae 16/22 (72.7%) after double puncturing

a vein. Junior Resident doctors successfully cannulate a vein in the 2nd attempt in 17.5 %

(14/40), the registrars in 36.35% (4/11) and the seniors in 14/22 (63.63%) of attempts.

DOCTOR One Two Three Four Five > Five Total

Junior Resident

32.5% (13) 20% (8) 35% (14) 5% (2) 5% (2) 5% (2) 54.79% (4)

Registrar 9.09% (1) 54.5% (6) 9.09% (1) 9.09% (1) 9.09% (1) 9.09% (1) 15.07% (11)

Senior Doctors

45.5% (10) 22.7% (5) 4.55% (1) 18.2% (4) 0% (0) 4.55% (1) 30.14% (22)

32.9% (24) 26%(19) 21.9% (16) 9.59% (7) 4.11% (3) 5.48 % (4)

(n=73)

Cannulae used

13.5% (24) 21.4% (38)

27.1% (48) 15.8% (28 ) 8.4% (15) 13.5% (24) 41.2% (73)

Cannula Discarded

18.2% (19)

30.7% (32) 20.1% (21) 11.5% (12) 19.2% (20)

58.7% (104)

The technique of cannulation involves identifying a good vein to cannulate, inserting the

needle through the skin and then slowly moving the tip of the needle forward. Noticing flash

back of blood in the collecting chamber indicate puncturing of the vein. After the vessel has

been punctured the cannula is slowly advanced over the needle to place the cannula in the

lumen of the vein.

The procedure of puncturing a vein (indicated by flash back) but failing to properly place the

cannula in the lumen was noted as "double puncture". If the flash back of blood was not

noticed this was recorded as "not double punctured" (failed to locate a vein). We also noted

observers comment and the reason given by the doctor after he failed to cannulate.

The duration of this observation was for two months. During this period we could observe

and collect information from seventy-three babies (n=73). 43 (58.9%) babies were less than

a month and 30 (41.1%) babies were less than a year. The average age of babies in our

study was 51.28 days. The average weight of these babies was 3.43 +/- 2.17 Kilograms

(range 0.63 Kg – 10.1 Kg

AGE of Children Junior Doctor Registrar Consultant TOTAL

< 1 Month 37.5% (15) 54.55% (6) 40.9% (9) 41.1% (30)

1 - 12 Months 62.5% (25) 45.45% (5) 59.1% (13) 58.9% (43)

TOTAL 54.8% (40) 15.07% (40) 30.1% (22) 100% (73)

Number of Attempts

0

5

10

15

20

25

30

ONE TWO THREE FOUR FIVE SIX

Junior Doctors Registrar Senior Doctors

The number of babies Junior Resident doctors attempted cannulating a vein was 40

(54.79%), Senior Resident doctors in 11 (15.07%) and the Consultants doctors in 22

(30.14%). Only 24 (32.9%) children were cannulated in the first attempt, 19 (26.0%) in the

second and 30 (41%) required three or more attempts

Attempts One Two Three Four Five > Five Total

Junior Resident (Failed)

20% (8) 15% (6) 27.5% (11) 5% (2) 2.5% (1) 2.5% (1) 72.5% (29)

Junior Resident (Success)

12.5% (5) 5% (2) 7.5% (3) 0% (0) 2.5% (1) 0% (0) 27.5% (11)

Registrs (Failed)

9.09% (1) 18.2% (2) 0% (0) 9.09% (1) 0% (0) 9.09% (1) 45.45% (5)

Registrar (Success)

0% (0) 36.4% (4) 9.09% (1) 0% (0) 9.09% (1) 0% (0) 54.55% (6)

Senior Doctor (Failed)

4.55% (1) 0% (0) 0% (0) 4.55% (1) 0% (0) 0% (0) 9.091% (2)

Senior Doc (Success)

40.9% (9) 22.7% (5) 4.55% (1) 13.6% (3) 0% (0) 9.09% (2) 90.91% (20)

32.9% (24) 26% (19) 21.9% (16) 9.59% (7) 4.11% (3) 5.48% (4) 100% (73)

One hundred and seventy seven (n=177) cannulas were used by doctors to successfully

cannulate these seventy three (n=73) children. The number of cannulae discarded due to

failure was one hundred and four (n=104).

The number of babies cannulated in the first attempt by Junior Resident doctors was 5

(12.5%) babies and Consultants doctors in 9/22 (40.9%). At the end of third attempt the

number of infants successfully cannulated by Junior Resident was10/40 (25%), Senior

Resident: 5/11 (45.45%) and Consultants: 15/22 (68.18%).

Doctors failed to locate a vein in 11/73 (15.1%), but failed to cannulate a vein after locating

(and double puncturing) in 25/73 (34.25%). Group doctors punctured and failed to

cannulate in 20/40 (50%), but the Consultants doctors punctured and successfully

manipulated the cannula into the lumen of vein in 16/22 (72.7%). Successfully cannulating

vein without any difficulty was almost equal when seniors (18%) were compared to Junior

Resident doctors (15%). Success and failure rate of these three group of doctors were

statistically significant (X2 = 22.91, p < 0.00001)

DOCTORS PUNCTURE (Found vein) NOT PUNCTURE (Not found vein) TOTAL

Junior Doctor 60% (24) 40% (16) 55.7% (40)

Registrar 91% (10) 9.09% (1) 15% (11)

Senior Doctors 77% (17) 22.7% (5) 30.1% (22)

69.86 % (51) 30.1% (22) 100% (73)

Junior Resident doctors to successfully cannulated 9/40 (22.5%) infants in 20 minutes,

Senior Resident doctors 4/11 (36.36%) and Consultants doctors 15/22 (68.18%). At the end

of thirty minutes the number of attempts increased but the proportional success rate

declined. Total number of attempts in twenty minutes was 52 (71.2%) and at thirty minutes

65 (89.0%). At the end of thirty minutes the rate of success was minimal (43.0% to 47.6%).

The average time spent on the procedure by the House officers (Junior Resident) was 0.32

min, the Registrar (Senior Resident) 0.34 min and the Senior Registrar (Consultants) 0.29

min.

The observers felt multiple punctures (11.5%), shock (5.2%) and oedema (4.2%)

contributed to failure. 71.5% of the children did not have any factor contributing to failure.

Cannulation of veins can be the most stressful but simple surgical procedure to perform and

difficult procedures to evaluate. The junior doctors find it difficult to accept failure and tend

to avoid the situation. Most doctors do identify and puncture the vein, but still find it difficult

to move the cannula forward into the lumen of the vein.

Junior doctors were reluctant to attempt cannulating when they noticed the child is obese,

oedematous or stopped cannulating at an early stage, as they were happy to hand over the

responsibility to the waiting senior doctor. They were not informed about the study as we

felt this might increase their anxiety and result in higher failure rate. The senior doctors

during this study cannulated babies who are considerably difficult to cannulate.

We noticed doctors who fail to cannulate have a tendency to quickly move the cannula

forward, once they notice the flash back of blood into the collecting chamber. The vein

proximal to the tip of the needle would have collapsed as the blood is draining into the

collecting chamber. It is advisable to pause for a few seconds or allow some time for the

collecting chamber to fill with blood before moving the cannula forwards into the lumen of

the vein.

The average number of attempts required by the doctors to successfully cannulate is 2.48

(0-6 attempts). It is advisable to initially allow doctors to have three unsuccessful attempts

prior to another doctor taking over the procedure.

Conclusion

We advice doctors to abandon the procedure after two attempts, as the failure rate

increases. This is due to lack of concentration by the doctor and difficulty to stabilise

distressed infants. The senior doctors master this technique of manipulating the cannula

after double puncture contributing to higher success rate. The percentage chance of

success without double puncturing a vein is almost similar in three groups. Failure to

cannulate is not due to difficulty in identifying the vein, but due to difficulty in propelling the

cannula forward.

The comments made by the doctors in our study were based on their own observations.

The result from our study should help doctors to improve the success rate making them

more confidants at cannulating veins. We feel this method of evaluating the technique

should be conducted in every tertiary centre to help doctors identify their deficiency and

improve their performance. This would reduce trauma to the infants and cost of paediatric

intensive care.

To reduce peripheral venous cannula spreading Invasive MRSA infection, adequate skin

preparation and time for adequate bactericidal action to occur must be followed (9). We

must also use sterile gloves because organisms colonising on latex gloves placed in ward is

not known. Band and Maki (1980) provide evidence to recommended changing cannula

every 72 hours. This evidence may not be relevant now because existence of MRSA was

not known before 1980. Failed cannulation and multiple puncture will result in trauma to

vein and may be predisposing phlebitis which results in spreading MRSA infection, bacterial

associated septicaemia and death due to toxic shock syndrome. Most studies published are

in post operative patients and association with phlabitis. Studies identifying association with

number of attempts taken, inadequate skin preparation and duration taken to introduce

cannula have not been published for us to comment.

We sincerely hope this publication will help others to identify causes which will reduce

spreading invasive MRSA infection in the community and also warn doctors and nurses to

take adequate care when introducing cannula. This proceedure which was not thought to

be threatening life has become a major contributor of mortality giving raise to ethical and

legal debate.

Reference

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(9) Care and maintence to reduce vascular access complication;

http://www.rnao.org/bestpractices/PDF/BPG_Reduce_Vascular_Access_Complications.p

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