3 Equipment and Environment Vikramaditya Prabhudesai

Equipment and Environment 13

3 Equipment and Environment

Vikramaditya Prabhudesai

V. Prabhudesai, MD

Diagnostic Imaging, St Joseph’s Hospital, 50 Charlton Ave (East), Hamilton L8N 4AG, Ontario, Canada

3.1

Introduction

There have been tremendous advances in techniques and technology since the first arteriogram by Dos Santos et al. in 1929. The role of an angiographer has evolved from diagnosing arterial and venous diseases to offering definitive treatment.

With this new level of complexity and skill comes a need to design an angiography suite capable of meeting this demand (Bakal 2003). The same room may also be used for non-vascular intervention. The requirements for such a suite are different from that of a cardiac catheter laboratory or a neuroradiology suite.

3.2

Angiography Suite

Ideally, all diagnostic and therapeutic vascu- lar procedures should be performed in a hospital based dedicated angiography/interventional suite (Cardella et al. 2003).

An ideal angiography suite must have adequate space for the radiological equipment, monitoring

and emergency care equipment as well as enough space for patient care and recovery (Fig. 3.1). An ideal examination room would be 65 m

. Large lead lined doors are needed which are wide enough to admit beds with ancillary equipment. The ceiling should be 3.5–4 m high with additional space above that to allow mechanical access. In addition, the fol- lowing features are needed:

1. The fl uoroscopy unit

2. Enough electrical points for ancillary equipment that may be needed

3. A scrub sink with hot and cold water and hand wash solution which is outside of the examina- tion room

4. A dirty utility room, with a sluice, adjoining the suite

5. Piped anaesthesia gases, suction machine and physiological monitoring equipment

6. Surgical ceiling mounted lights and ceiling lights that can be dimmed

7. Storage space, apron rack and shelves for all the equipment

8. Ultrasound machine, with an additional monitor next to the fl uoroscopy monitor

9. Manometry equipment for measurement of arte- rial (pulmonary or peripheral artery) and venous pressures

CONTENTS

3.1 Introduction 13 3.2 Angiography Suite 13 3.3 Fluoroscopy Equipment 14 3.4 Environment and Patient Care 15 3.5 Consumables 15

3.6 Conclusion 16 References 16

Fig. 3.1. An ideal angiography suite

14 V. Prabhudesai

If the room is to be used for endovascular stent grafting for aortic aneurysms, then operating room standards must also be met. A management plan in case of complications or emergencies should be in place.

The control room is separate, and lead lined glass allows visualisation of the suite. An intercom is useful, whilst the use of blinds may be necessary in certain cases. The control room should have a computer which can access the patient records and all labora- tory investigations in addition to monitors and X-ray viewers that will allow review of previous imaging.

An air conditioned room for the power equip- ment, transformer and other electrical equipment is needed with an additional room for storage of con- sumables.

A recovery room with patient bays, each with the necessary monitoring equipment is essential.

Patients may be kept here and monitored till trans- port to appropriate wards or day care centres. Addi- tional support space for staff, patients and relatives may be shared with the general radiology depart- ment or be dedicated to the angiography suite.

3.3

Fluoroscopy Equipment

The fluoroscopy unit (Pooley et al. 2001) must be a ‘C’ or a ‘U’ arm unit which can rotate around the patient in the axial and the sagittal planes. The unit is motor driven with the angles displayed on the monitor/control unit. It should be possible to vary the source detector distance. Combination of fluoroscopy arm and table movement should make imaging of the whole body possible. Manual over- ride and locking should be possible. Modern equip- ment also has built-in systems to prevent collision and patient injury or damage to equipment.

The table should have a floating top and be able to support at least a 140-kg patient. As CO

angiog- raphy is being used more frequently the table should also have lateral tilting capabilities, in addition to head up and head down positions. There should be an extra set of controls on the table for use by the angiographer. It should be possible to move the C-arm away or move the table out from under the arm in case of emergencies.

The image intensifier should have a large field of view with at least two or three field sizes. Digital subtraction and acquisition (DSA) is standard on all present-day fluoroscopy units. There are many

modern systems on the market, with most or all of the following:

1. Pulsed fl uoroscopy for dose reduction 2. Variety of frame rates (1–15 frames/s) 3. Various collimators

4. Dose free display of fi lter and collimation posi- tion

5. Filters to reduce skin dose 6. Image overlay

7. Road mapping and land-marking 8. Last image hold and frame-grab

9. Automatic table movement/stepping allowing imaging of a limb with a single contrast injec- tion

Excellent image quality is a must and is pro- vided by a large matrix, usually 1024u1024, and some modern systems provide a higher resolution of 2048u2048. Some newer systems have flat panel detectors. Other requirements for image processing, display and archiving include:

1. Frame averaging to form and change masks 2. Post acquisition image enhancement 3. Pixel shifting

4. Annotation 5. Cine display

6. Histogram creations

7. Windowing and contrast/brightness changes 8. Flow measurements

9. Region of interest (ROI) and distance measure- ments

10. Stenosis quantifi cation

11. Maximum opacifi cation (view trace) and a vari- ety of other image manipulations

Newer units have increased functionality includ- ing fluoroscopy storage and rotational scanning/

imaging. The latter allows three-dimensional imag- ing of complex vascular structures in multiple pro- jections with just one contrast injection. Although the most common use of such equipment is in the neuroangiography setting, it can be of value for imaging of iliac arteries and renal transplant arteries.

A system for the angiographer to review all the images should be incorporated on the unit. Having two monitors helps in case of complex procedures where multiple series need to be reviewed and a ref- erence image is required; failing this, it should be possible to split the main screen. Ceiling suspended monitors should be positioned so that they can be viewed from either side of the table.

Power injectors capable of varying the rate of

contrast injection are needed. Additionally a CO

Equipment and Environment 15

injector may be needed, although it is possible to fill a syringe from a CO

cylinder and perform a hand injection. The injector should have visual and audible malfunction signals. It should display the parameters such as volume, rate and pressure of each bolus injection.

3.4

Environment and Patient Care

All procedures are performed in strict aseptic condi- tions. Sterile gowns and gloves in addition to masks and caps are worn by the operators and their assis- tants. Eye protection is advisable to avoid splashes and sterile coverings are used for any equipment that may contaminate the field. All staff must follow full aseptic techniques in the preparation of the carts and for handing over equipment, instruments and consumables. The handling of all ‘sharps’ must be in accordance with occupational health regula- tions. Universal precautions need to be followed when handling patients and any body fluids.

Resuscitation equipment and the expertise for its use must be available to deal with the complications that may occur during interventional procedures.

The interventional suite must be equipped with a standard hospital approved ‘arrest trolley’. This must have the full complement of drugs, defibrilla- tor, breathing masks/bags and intubation kit.

The vast majority of cases are performed under local anaesthesia. Conscious sedation is used in some cases (see Chap. 5). In rare cases general anaesthesia is used, hence suitable facilities and equipment must be available for such occasions. During the proce- dure all vital signs need to be recorded. Cardiac monitoring is performed routinely, whereby it is more important for pulmonary angiography. Intra- venous access is mandatory in all cases for fluids, sedation and any medication as may be needed. An appropriately qualified nurse monitors the patient throughout the procedure, keeping a record of all medication given.

The patient needs continuous monitoring follow- ing the procedure. This is done in an appropriate setting of a recovery room, or a similar unit. Bed- rest is mandatory, the duration depending upon the type of procedure. The vital signs are recorded and the puncture site is inspected. In case of any com- plications the nursing staff has to inform the physi- cian in charge immediately. A written record of the procedure is made, along with appropriate findings

and immediate complications if any. It is important to communicate with the referring physician in case of the latter. The duration of stay in hospital fol- lowing a diagnostic or therapeutic procedure will depend on hospital and department policy. Many procedures are being performed on an out-patient basis. Some complicated cases, however, still require at least overnight admission, not least for pain con- trol. Strict discharge criteria need to be formulated, which must be met before the patient can go home.

The patient is usually followed by the referring physician. Multi-disciplinary meetings are useful for feedback and also to formulate treatment plans.

3.5

Consumables

A basic sterile tray is needed in each case. This may be disposable or reusable after appropriate steriliza- tion. The components of this tray include basins for the antiseptic solution, saline flush, soaking of wires and catheters; sterile instruments, and the neces- sary needles, wires and catheters.

There is a wide variety of needles, guidewires and catheters available for use by an interventional radiologist. Available needles should include micro- puncture kits, single-wall and double-wall puncture needles in 18G or 19G sizes.

Most guidewires are made of stainless steel coil wrapped tightly around an inner mandrill that tapers to the working end. There is a central fila- ment which prevents separation if the wire breaks.

Wires are available in a variety of sizes (from 0.010 to 0.038 in. in diameter) and lengths (50–300 cm).

Other characteristics include a variety of tip config- uration (straight, angled, ‘J’ shaped, tapered, floppy and tip-deflecting), torquability, stiffness and outer coating (hydrophilic wires). Teflon coating reduces friction. Some wires are impregnated with heparin to reduce thrombogenicity. In addition to steel, nitinol, platinum and gold are used in wire construction. To increase the useful life, wires should be wiped with saline soaked gauze each time the wire is removed or catheter exchanged. If possible the wire should be stored in a saline bowl, as build-up of thrombus or dried contrast may make the wire useless.

Angiographic catheters are made of Teflon, poly-

urethane, polyethylene or nylon and are designed for

safe and efficient vascular cannulation. A large vari-

ety of catheters are commercially available. Hydro-

philic coating on catheters improves trackabilty

16 V. Prabhudesai

and wire braiding improves torquability. Catheters vary in size, length and number of side holes and shapes. Catheters should be kept wet and flushed prior to use. Intermittent flushing improves the life and reduces the incidence of clot formation at the tip of the catheter. A range of sheaths are also avail- able which help with reducing oozing from the site of vascular access. In addition they prevent vessel wall injury when multiple catheters are exchanged and when angioplasty, thrombolysis or embolisa- tion is planned.

A wide variety of balloon and covered and non- covered stents are available. These are available in different sizes and lengths. Infusion catheters for thrombolysis, atherectomy devices, Fogarty cath- eters for clot retrieval and a variety of snares and vascular biopsy and foreign body retrieval instru- ments are commercially available. In addition there is a huge armamentarium of embolic agents at the disposal of the vascular radiologist. More details are beyond the scope of this chapter. However, it should be emphasised that before embarking on any pro- cedure the interventional radiologist should ensure that he has the full range of equipment likely to be required to complete any given procedure. In addi- tion, equipment and drugs required to treat any complications that may occur should also be avail- able. Examples would include stent grafts for the treatment of vessel rupture and aspiration catheters and thrombolytic agents for the management of peripheral emboli.

3.6

Conclusion

In the last two decades interventional radiology has advanced hugely. Treatment may be highly com- plex with significant potential complications. It is therefore essential that good imaging equipment is available in a clean, preferably theatre standard, and spacious environment. A sufficiently wide variety of equipment in the form of guidewires, catheters and so forth should be available to allow procedures to be completed safely. In particular, there should be equipment available for the management of com- plications.

References

Bakal CW (2003) Advances in imaging technology and the growth of vascular and interventional radiology: a brief history. J Vasc Interv Radiol 14:855–860

Cardella JF, Casarella WJ, DeWeese JA et al (2003) Optimal resources for the examination and endovascular treatment of the peripheral and visceral vascular systems. AHA Inter- council report on peripheral and visceral angiographic and interventional laboratories. J Vasc Interv Radiol 14:

S517–S530

Dos Santos R, Llamas AC, Pereira-Caldas J (1929) Arteriografia da aorta e dos vasos abdominais. Med Contemp 47:93 Pooley RA, McKinney JM, Miller DA (2001) The AAPM/RSNA

physics tutorial for residents digital fluoroscopy. Radio- graphics 21:521–534