Cath Lab Safety

It’s 3 am and you’re finishing a ST-elevation myocardial infarction (STEMI) in a 61-year-old woman with a body mass index (BMI) of 35 (weight 256 lbs, height 5’2”) with a large pannus and protruding abdomen. The procedure was done via radial approach with a Velcro strap over the legs (Figure 1), since she was uncomfortable and actively moving her legs before the procedure. The catheters were removed. Hemostasis was obtained with a radial pressure band and her arm placed at her side. The nurses were undraping the patient, closing their notes, moving the equipment table to the side and opening the cath lab door to bring in the transport stretcher into the lab. In the next moment, the patient rolled off the table with a thump. The patient hit her head since her legs were kept partly on the table by the Velcro straps.  

After evaluating the patient and finding no serious injury, the patient was returned to her intensive care unit (ICU) bed. The doctors addressed the fall with the patient and her family. The event was documented as best as possible in the nursing note. The next morning, risk management was notified and the cath lab staff convened a meeting on improving cath lab safety. Although the patient survived the fall, and the situation was assisted by doctors, nurses, and risk management, a law suit was filed implicating the staff, the doctor, and the hospital. What could have been done to make the lab safer?  

The cath lab, like any operating area in a hospital, has potential injury risks for both patients and staff.  The common risks of any operating room are listed in Table 1. Good sense and proven work routines help us take precautions against accidents. Specific situations in which potential patient-related accidents should also be considered and attended to are in the routines of careful transfer of the patient to the table, centering the patient on the stable, and removing any sharps or hard-edged objects from contact with the patient. One unresolved issue is whether all patients should be restrained on the cath lab table.

Restraining straps?

In the operating room, it is common to secure the patient on the operating table with restraining straps (Figure 1), because of table tilting or angulated positioning, and the unconscious patient under general anesthesia. During the operation, general anesthesia renders the patient immobile and unable to keep minimal balance even while completely flat. Since some operations require the body to be turned to or away from the operator, the OR table may be tilted and without some restraints, the patient could easily roll off.

The OR conditions and its requirements do not translate to the cath lab. For most procedures, the patient receives conscious sedation, not general anesthesia. Patients are semi-awake for most of the procedure. The cath lab table is never angulated or tipped in any way. The patient may be aware of his position on the table and be able to move his body on command, but also is more awake and therefore more active, and can accidently move too much, potentially moving off the table’s edge.  

Some cath lab patients need ‘gentle reminder’ restraints to keep their arms at their sides, or keep their legs from twitching or kicking. Another common use of restraining straps may be for automated implantable cardioverter-defibrillator (AICD) implants. The restraints help keep the patients still for device function testing. For patients with active arms, padded restraints on the wrists will do this job well, but it should alert the nurses that they are working with a potentially ‘active patient’ who may do more than just raise his arms. For some patients, a strap around the abdomen or legs may be used.  However, these straps cannot really keep a patient on the table, especially if the patient’s center of gravity moves far off the table’s mid line. Think of trying to keep a water balloon tied around the center with a ribbon on a flat board. Moving the board (as one might move the cath lab table) shifts the center of mass, and the balloon will move to the side and may even escape its restraint.  

Should the time-out also include a fall risk assessment?

As part of procedural safety, every patient coming to the cath lab must be assessed regarding suitability for conscious sedation and potential complications of the cath procedure. Every lab is required to perform a pre-procedure safety review, called a time-out (Figure 2). Before sedation, in the time-out, the team verifies the right patient is in the room, the right procedure is going to be performed, the right operative site will be used, and whether the patient has renal failure, allergies, or is in an anticoagulated state. At this time we, the team, agree to proceed, and then identify what analgesia and sedation dose will be given. I think that during the time-out and after the administration of conscious sedation, we should assess all patients for their ‘fall-off-the-table’ risk. While rarely a worry, we should consider it in certain patients who may be considered at high risk.

Who are patients at high risk for falls?

While fortunately a truly a rare occurrence, most of the falls from a cath lab table occur in high BMI patients. Strategies for catheterization in morbidly obese patients (Table 2) has been addressed in an earlier editor’s column.¹ In more than 30 years working in cath labs in the Northeast, Texas, Missouri, and California, I know personally of less than 5 reports of falls from cath lab tables. Unfortunately, falls can have serious consequences. I was told that there was one death from a subdural hematoma and one shoulder injury. All patients were obese and were very active at the time of the fall. Any patient who cannot follow simple instructions, or is agitated or uncooperative, should be considered to be at high risk. Patients who cannot keep their arms at their sides, or keep their legs still or body still on the table are at high risk. These are the same patients who may also fall during transfer on or off the cath table. To my knowledge, there is no formal algorithm for deciding who is truly at “high risk”. All labs use operator and nurse judgment at the time of the procedure.  

Are restraints effective to prevent falls?

In an attempt to prevent rolling off the table, some labs use large straps across the patient’s legs or around the middle of those whose bodies extend over the sides of the cath table. Large, plastic, curved arm boards may also assist in keeping the patient secure on the cath lab table. In some settings, the straps act to keep arm boards attached to the table. There is no perfect strap or method to hold patients on the cath lab table. Commercially available strap systems are also promoted as helpful, but with little proof. Despite our best efforts, efforts accidents can occur (Figure 3).  

Bottom line

Compared to most operative areas, the cath lab has an exceptional safety record. To maintain this high standard, we should continue to review and assess all patients coming to the lab for potential complications, accidents, and inadvertent injury. The time-out can serve to increase our situational awareness of any additional conditions or considerations that may improve patient safety and outcomes.

References

1. Kern M. Reducing complications in the very high ‘BMI’ patient. Cath Lab Digest Oct 2012; 20(10): 4-8. Available online at https://www.cathlabdigest.com/articles/Reducing-Complications-Very-High-%E2%80%98BMI%E2%80%99-Patient. Accessed March 19, 2014.
2. Vanhecke TE, Berman AD, McCullough PA. Body weight limitations of United States cardiac catheterization laboratories including restricted access for the morbidly obese. Am J Cardiol. 2008; 102: 285-286.
3. Kussmaul WG 3rd, Bowers B, Dairywala I. Method for coronary angiography in morbidly obese patients. Catheter Cardiovasc Interv. 2005 Jun; 65(2): 268-270.