Monitoring the patient should be continually performed from the beginning to the end of the case, so that potential complications are promptly identified and corrected. The following parameters are assessed ( Fig. 2.1 ).
Patient comfort level: patient discomfort can lead to movement, potentially leading to complications. It can also lead to tachycardia and tachypnea, which may in turn worsen ischemia.
Chest pain, abdominal pain, groin pain? Is the pain anticipated based on the procedure or is it unexpected? The pain could be due to ischemia, perforation, or other complications.
Level of consciousness and breathing. Is breathing assistance needed (BiPAP or intubation)?
Ability to move all extremities (no stroke) or conversely excessive movements that may hinder performance of the procedure.
Signs of allergic reactions: skin rash; itching and hives; swelling of the lips, tongue, or throat; hypotension.
The ECG morphology and heart rate should be evaluated at the beginning of the case, so that subsequent ECG changes can be promptly identified.
Electrocardiographic changes of concern include:
New ST segment depression.
New ST segment elevation ( Fig. 2.2 ).
Ventricular premature beats during wire manipulations.
The arterial pressure should be continuously monitored.
Pressure waveform changes of concern include:
Hypotension (see Section 28.1 )
Pulsus paradoxus ( Fig. 2.2 )
Pressure waveform dampening or disappearance (see Section 188.8.131.52 .) that may reflect the true aortic pressure, or may be due to:
Deep guide catheter engagement or engagement of coronary arteries with ostial lesions. Injections should not be performed while the pressure waveform is dampened, as they can lead to coronary or aorto-coronary dissection and/or air embolism.
Air entrainment within the guide catheter (e.g., when using the trapping technique for equipment exchange).
Thrombus formation within the catheter. Injecting in such cases can lead to coronary or systemic thromboembolism.
Guide catheter kinking.
Insertion of equipment: for example, inserting an aspiration catheter, such as the Export into a 6 French guide catheter may lead to pressure dampening.
Disconnection of the pressure transducer.
In patients who develop hypotension and in heart failure or shock patients, placement of a Swan Ganz catheter can facilitate decision making regarding hemodynamic support and also help detect any new hemodynamic changes ( Section 28.1.1 ).
Oxygen desaturation may be due to hypoventilation due to heavy sedation, but it can also be due to early pulmonary edema, artifact, or other causes. Full arterial blood gas can provide more comprehensive information about the patient’s oxygenation and metabolic status.
Radiation dose—X-ray system and shield positioning
The cumulative air kerma and DAP radiation dose should be continuously monitored. Usually the procedure is stopped if the air kerma dose exceeds 5–7 Gray. An air kerma radiation dose higher than 15 Gray is a sentinel event ( Section 28.2 ).
The dose rate is another dynamic parameter that can be tracked.
There are also continuous operator dose monitoring devices (such as the DoseAware, Philips) that can alert to high operator doses in real time, alerting the operator to the need for changes to reduce high radiation dose.
The position of the various shields and the image receptor should be continually monitored and adjusted to minimize patient and operator radiation dose.
This can be tracked automatically by some systems (such as the ACIST injector and the DyeVert Plus system). The procedure should generally be stopped before reaching a contrast volume ≥ 3.7× GFR, although a lower threshold is preferable in patients with chronic kidney disease or single kidney ( Section 28.3 ). Recent contrast administration (for example in patients who had contrast computed tomography) should be taken into consideration when determining the contrast threshold.
The pulses at the access site and distally should be assessed at the beginning and the end of the case.
Bleeding and hematoma formation can occur at the access site(s)—continuous inspection and palpation can help in early identification ( Chapter 4 : Access).
Medication administration (anticoagulation—ACT, sedation, other medications)
Sedation ( Section 3.1 ) is given in nearly all patients and should be titrated to achieve acceptable patient comfort without compromising respiratory or hemodynamic status.
Anticoagulation ( Section 3.4 ) is achieved with unfractionated heparin in most procedures and monitored using ACT (activated clotting time). Goal ACT (Hemochron device) for PCI is 300–350 seconds for most procedures or >350 seconds for retrograde CTO PCI. When glycoprotein IIb/IIIa inhibitors or cangrelor ( Section 3.5 ) are given, goal ACT is 200–250 seconds.
Operator and team performance
Paying attention to the operators’ and team’s operational state can help identify conditions that may lead to suboptimal outcomes, such as excessive fatigue.
Cath lab environment
Avoiding excessive noise and distractions is important for better outcomes.
A rule analogous to the “sterile cockpit rule” for flying should be implemented during the critical parts of the procedure. The “sterile cockpit rule” is an informal name for the Federal Aviation Administration regulation stating that pilots shall not require, nor may any flight crewmember perform, any duties during a critical phase of flight , except those duties required for the safe operation of the aircraft.
Sterile field and equipment
Keeping the equipment and table organized will facilitate equipment identification and use.
Dried blood and contrast can make the operator gloves and various types of equipment (guidewires, catheters, balloons, stents, etc.) “sticky” and could also create risk of embolism if debris enters the manifold. Regularly wiping the gloves and equipment and flushing the catheters with heparinized saline will facilitate equipment handling and reduce the risk of complications.
Equipment position within the body
The position of equipment inserted into the body (such as sheaths, guide catheters, guidewires, balloons, stents, etc.) should be constantly monitored for both efficacy and safety.
A classic example is guide disengagement while attempting to deliver balloons and stents, when the operator often focuses on the equipment that needs to be delivered (such as the stent) and does not pay attention to the guide catheter, which may become completely disengaged leading to loss of guide and guidewire position. Conversely, deep guide engagement may result in dissection and acute vessel closure ( Section 25.2.1 ), especially if contrast is injected.
Another example is not monitoring the location of the guidewire tip (especially when collimation is used to minimize radiation dose), which may enter into small branches and result in distal vessel perforation ( Section 26.4 ).
Who is assessing the above parameters:
The primary and secondary operators.
The cath lab technician (traditionally a technician is constantly monitoring the ECG and pressure tracings).
The cath lab RN (who monitors the ECG, pressure, and O 2 saturation). The cath lab RN is usually administering the various medications (sedation, anticoagulation, antiplatelet agents, etc.).