Precath Preparation

Dr Fuad Farooq

Preparation of the Patient

• Elective cardiac cath should be deferred if the patient is not prepared physiologically and physically

Consent

• Detailed discussion with the patient and family• Should be obtained by the operator or his or her

assistant– Should outline the indication of procedure – Explain in simple terms which procedure to take place and for

what reason each step of the procedure will occur– Explain the risk for routine cardiac cath

• Major- stroke, myocardial infarction, kidney failure, death• Minor- vascular injury, allergic reaction, bleeding, hematoma,

infection• Possible need of emergency CABG

– Explain any portion of the study used for research – Provide necessary information and explanation

History

• Including– Reason of cardiac cath– Precious allergies to dye, sea food– Asthma, allergic rhinitis– Medications esp. ASA, Clop, Metformin,

anticoagulants– History of kidney disease– In female, if child bearing age, ask especially

for pregnancy

Examination

• Thorough general physical examination should be done

• All peripheral pulses should be palpated and documented

• Look for arterial bruit and document it as a baseline for future reference

• Perform Allen’s test if radial approach • Auscultate chest• Look for murmurs

Metabolic Profile

• Renal function e.g. BUN, creatinin

• Electrolytes e.g., Na, K

• CBC

• Coagulation profile

• Any abnormality in the lab should be addressed before proceeding to LHC

• Precath orders preferably written on preceding night– If patient on long acting insulin dose should

be reduced to half– NPO at least 8 hours before procedure– Shave both groins for femoral access and

mostly right wrist for radial approach• Avoid laceration or abrasions

– Apply Foley’s catheter or external/sheath catheter in male

Choice of Dye

• Now a days mostly nonionic low osmolal dye is used– Causes less nausea and emesis, LV dysfunction,

bradycardia and hypotension– Useful in cases of suspected LM stenosis, severe LV

dysfunction, and severe aortic stenosis– In patients with renal insufficiency and reported

allergy to contrast dye– More thrombogenic than ionic dye so used with

caution- use 5 IU of heparin per cubic centimeter of contrast

Contrast Media Reaction

• Incidence 5%• 10-12% patients has history of asthma• 15% patients has the history of previous reaction

to the contrast media• Three types

– Cutaneous and mucosal manifestations (angioedema, flushing, laryngeal edema, pruritis, urticaria)

– Smooth muscle and minor anaphylatoid reaction (bronchospasm, GI spasm, uterine contraction)

– Cardiovascular and major anaphylactoid reaction (arrhythmia, hypotension, vasodilatation)

• More risk with the ionic contrast media than non-ionic contrast media

• Any patient reported previous allergy to the contrast media or history of atopy or prior anaphylactoid reaction should be premedicated with– Steroid ( prednisolone 40mg PO Q6H or I.V hydrocortisone

100mg once at least 6 hours before the procedure– Diphenhydramine ( Benadryl 50mg I.V once )– H2 blocker ( Clemestine 1mg I.V once)

• If history of life threatening dye allergy, it is prudent to admister 1ml of dye and watch for few minutes before proceeding

Contrast Media Reaction..

Contrast Induced Acute Kidney Injury

• High risk patients are – Patients with diabetes– Patients with renal insufficiency (Cr >1.5)– Patients who are dehydrated due to any reason

• Prevented by– I/V hydration with 0.9% saline ( LV function should be taken into

consideration for selection of rate of infusion) • Dose: 1ml/kg at least 2 hours before procedure and ideally Upto 6-

12 hours before procedure and continue Upto 6-12 hours post procedure

– Alkalinization of urine prevent free radical injury to the kidney• Dose: 3 ml/kg for one hour before procedure and continued as

1ml/kg/hr for 6 hours post procedure

Contrast Induced Acute Kidney Injury

– Acetylcysteine- has antioxidant and vasodilator properties

• Must be accompanied by I/V hydration and use of low or iso-osmolal contrast agent

• Risk reduction Upto 50%• Dose: 1.2 gm P.O twice a day starting day before the

procedure and continue for two days post procedure (I/V admistration if in emergent procedure and orally cannot be given-150mg/kg prior procedure and 50mg/kg post procedure over 4 hours)

– Using low osmolal or iso-osmolal nonionic contrast media (use in lower dose)

– Avoid closely spaced studies (<48 hours apart)– Avoid NSAID’s

Diabetes Mellitus

• Patient with diabetes on insulin therapy, overnight fast with normal dose of insulin can cause hypoglycemia– Dose if insulin should be half– Patient on NPH insulin has increase risk of protamine reaction

• Patient on Metformin, withheld it 48 hours before procedure because of risk of lactic acidosis especially in patients with renal insufficiency – may resume after 48 hours only when renal function are found to

be normal– Hydrate the patient before during and after the procedure ( i.v

saline @ 1ml/kg/hr)

Patient Education

• Patient should be warned that they might feel hot sensation for few seconds when contrast is injected, some patients may feel nausea

• Patient should specially instructed to cough when they hear anyone in the cath lab say “cough” – this will accelerates resolution of dye induced bradycardia

Equipment

• Before performing cath it is very essential that the monitoring equipment is fully functional

• Continues ECG recording, heart rate, rhythm, ST segment an automated BP and pulse oximetry are essential

• Resuscitation equipment should be tested and ready – defib and intubation trolley should be next to the patient