A Primer for Students Regarding the Cardiac Intensive Care Unit and Operating Room Basics: Primer 5 of 7

It is commonly said that the greater the number, the smaller the suture, and this is true for all sutures smaller than size 0 (pronounced “oh”). Size 0 is the largest size suture one is likely to see in practice, and thicker sutures are generally called “number” 1 and higher for increasing sizes. Larger sizes are most commonly used as free ties to secure tubes and sometimes as retention sutures during difficult closures. From size 0 progressing to smaller, sutures are described as 2-0 (pronounced “two-oh”), 3-0, 4-0, continuing toward very small sizes such as 10-0 (0.02 mm). A more detailed description of usage of different sutures depending on size can be found in Table E1.

Absorbable sutures are best for tissues that heal quickly and in situations in which removal is difficult. They will start to lose strength somewhere between 1 and 3 weeks depending on the material and are typically absorbed entirely within 3 months, although duration will vary by material. Nonabsorbable sutures are used when strength needs to be maintained long-term or healing is of a longer duration. Sternal and fascial closures are 2 examples of times when permanent material is desired. These are left in the body long-term and carry a risk of infection that can require removal. Both absorbable and nonabsorbable sutures can be made from natural and synthetic materials. See Table E2 to obtain more information of materials, tension, and tissue reactivity of commonly used sutures.

To learn how to suture, start by exploring instructional resources with a suture kit and materials (can be purchased on Amazon for approximately $30 US or obtained at your school's simulation laboratory). Instruments required to get started include a needle driver, forceps, suture, and scissors. Often suture can be obtained from the OR after cases. Many times, all that is needed is a friendly request to the resident or scrub nurse and the clean, unused sutures can be obtained after cases.

Drapes are used to minimize microbial migration, and contamination from nonsterile to sterile areas are minimized by isolating the incision site and creating a sterile field with the use of drapes. Although not always obvious in a prepped patient, sterile team members must avoid contact with the undersurface of the drape, as it is considered contaminated. Once a drape has been positioned, it should not be repositioned. The top of draped equipment, such as the OR table, back table, and prep table, are considered sterile. The portion of the drape hanging below the edge is considered nonsterile.

Why does the surgeon choose one position and draping method over another for each case? When trying to decide how this should be done, consider 3 things.

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  What is being operating on and what incision will be used to access and expose this area? Consider the aortic arch. If access is needed to any area proximal to the left subclavian, a median sternotomy would offer the best exposure. To facilitate this, the patient would be supine and the drapes from the chin, out to the nipples and down to the knees (assume groins should always be prepped in for urgent vascular access in median sternotomy). If the aortic pathology were distal to the subclavian, it would need to be approached from a thoracotomy and possibly laparotomy, requiring left lateral elevation and placing the arms on the same side of the body.
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  What access will anesthesia need to safely monitor the patient? Positioning and draping must allow for intravenous access, monitoring (transesophageal echo, neuro, etc), and intervention when needed (ice to the head during circulatory arrest).
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  What are the most common intraoperative complications and what access will be needed to address these? Consider an acute type A dissection. Although the imaging may suggest that this will only require an ascending repair, the axillary area and groins should be prepped so that alternative cannulation can be achieved quickly if the dissection progresses or the dissection is more extensive than expected.

The most efficient way for a student to learn to prep and drape is to introduce themselves to the OR staff and show up before the case with enough time to ask the team if they would be willing to teach the steps. Often the first time working with a team, this involves verbal instruction then progresses to having the student do this part of the case. Investing in this process can build trust and facilitate more opportunities.

Description of common surgical positions used in cardiothoracic surgery are shown in Table 1.

When planning to scrub, students should get their own gown and gloves and give them to OR staff beforehand. Once scrubbed, it is critical to notify the OR staff immediately if you inadvertently contaminate yourself or part of the field. Simply notify the team and prepare to re-gown or re-glove. Do not argue if a member points out a breach. To maintain a patient-centered focus, it is critical that you demonstrate the ability to heed the concern of the team and re-scrub. Do not take instruments from the scrub nurse's table without first asking permission. Each scrub will have a setup that allows for quick access to instruments at critical points, and disturbing the setup without communication will be detrimental to efficiency at key moments. Remember that “please” and “thank you” are simple reminders to the staff that you appreciate and value their efforts to accommodate your learning process. In the cardiac operating room, there is an appropriate time to ask questions. This can be tricky for a student new to the cardiac OR, as silence is often a sign that the surgeon is concentrating on a challenging aspect of the case and a calm demeanor is required for even the most critical points. Some favorable times for questions are when giving cardioplegia or waiting for an instrument to be brought to the room. Less-favorable times would be during circulatory arrest, going on or coming off pump, and when tying sutures. However, if an instruction wasn't clear, students should ask to clarify, never assume. Using the phrase, “I’m not sure what you mean by XXXXX. Could you say it a different way?” is a succinct way to communicate that and prompts the surgeon to refrain from using colloquial terms in favor of the more formal terms that students have often read. The same thing is true when cutting sutures: ask whether to leave a long or a short tail and make sure to pay attention to why each type of suture is cut at what length. When holding retractors or a camera on a laparoscopic case, try to take up the least amount of space while giving the surgeon the widest field of vision possible.

Management of postoperative CTICU patients can vary widely by hospital system and often by specific surgeons within the same hospital system. Expect that each patient will behave a little differently in the postoperative period based on the consequences of their underlying medical conditions and the surgical intervention performed. It is also common for hospital systems and/or surgeons to have a guide or pathway for postoperative management that serves as a starting point for management in uncomplicated patients. Many of the items on these pathways are quality metrics and can be obtained from the ICU or resident team. Often, the student will have to ask for these documents or about the pathway, as it will have become routine for the ICU team. Learning these pathways will help the student anticipate next steps and what is likely to be prioritized at different phases of care. Knowing what information the team is likely to want each day can help the student become a functional member of the team rather than remaining in the observer role.

It is important to pay attention to when certain things are occurring for a patient and why so that next steps can be anticipated. Some examples can be found on Table 2.

The ultimate goal for a patient in the ICU is to improve so they can get to the next step—getting out of the ICU. Figuring out what is the barrier for the patient getting out of the ICU is important: do they need better hemodynamics, do they need better pain control, is it a placement issue? What things can we manage for the patient to help them progress? Using this question helps to understand the priorities of an ICU team when there are multiple complex management plans occurring simultaneously.

After a patient is transported from OR to the CTICU, hemodynamics takes center stage. The hemodynamic measurements offer a quantitative overview to many processes on a minute-to-minute scale. Pre- and intraoperative events, along with the patient's comorbidities, are important to note when assessing the absolute numbers displayed on the monitor. To simplify, hemodynamics are the result of 3 key processes:

• 1.
  Cardiac function—the heart must generate enough forward flow to maintain adequate pressure. This initial finding allows the team to gauge whether cardiac function is adequate for tissue perfusion.
• 2.
  Vasoplegia—between medications, hypothermia, and age, nearly all patients experience some vasoplegia intraoperatively, and most will persist through the immediate postoperative period. Pressors (norepinephrine and vasopressin) are commonly used to decrease the vasoplegic component of hypotension.
• 3.
  Volume—when patients are hypotensive with good cardiac function (cardiac index >2.2 or transesophageal echocardiogram showing good ventricular squeeze) and not having a sustained response to a steady pressor dose, it's time to consider volume. The most direct way to assess this is with echo and looking at the volume in the heart. Central venous pressure is a convenient surrogate but can be misleading in patients with heart failure. If bleeding is significant (there will be chest tubes), consider suggesting that the team evaluate how the patient would respond to volume. It's important to understand laboratory values such as platelets, international normalized ratio, partial thromboplastin time, thromboelastography (a quantitative measure of whole blood's ability to clot) results to decide whether there is a derangement and what is needed to correct the laboratory values (albumin, blood, platelets, fresh frozen plasma, cryoprecipitate, or other product). Thromboelastography, while a newer tool, is increasingly used and will be important to understand.

There are many things to consider in the management of a postoperative CTICU patient, and the complexity can be overwhelming. However, there a few consistent parameters that require action on the part of the surgical team. Paying attention to these parameters offers the student opportunities to further contribute by alerting the team to changes and learning from the response. Chest tube output that is persistently greater than 200 cc/h or chest tube output that changes suddenly can indicate the need for re-exploration or more detailed investigation of contributors to coagulopathy. When presenting this information to the team, the student would benefit from knowing the latest laboratory values and hemodynamic trends. Decreases in urine output can be an early warning of systemic malperfusion and the need for potential dialysis access in the patient with anuria. To help determine the need for dialysis, it is helpful to know if the patient can manage electrolytes (potassium is a good marker), acid–base status (look at the pH on the arterial blood gas), and volume, ie, has the respiratory support changed? Changes in the heart rhythm, particularly frequent nonsustained episodes of ventricular arrhythmias, can be an early warning of ventricular ischemia. In the postoperative revascularization patient, this may indicate a graft that is in distress. In arterial grafting, this may indicate vasospasm, and medication changes may be needed. In venous grafts, this may indicate the need for further investigation by the team. Acute changes in neurologic status, particularly after aortic cases or in cases in which the patient has a high atherosclerotic burden in the aorta, are concerning for postoperative stroke. This is an important finding and even in cases in which acute intervention is not advised will alter the blood pressure and anticoagulation plan for the patient.

It is helpful to know how the residents are organizing presentations to the attending. Presenting information in a predictable order allows the listener to mentally organize the data and offer feedback. It is helpful to ask the resident how they organize the data for particular attendings or to listen to a presentation and make a template for gathering data. One example can be found on Table E4.

Knowing the details of the patient data that allow for forward progress, such as when a patient can begin diuresis, meets criteria for chest tube removal, or is ready for but has not been evaluated by physical therapy, can really help keep the ICU moving and avoid bogging down the team. Keeping track of bowel status, neurologic status, inputs and outputs, and other factors can keep rounds moving and make sure the surgical team has knowns how patients are progressing after surgery.

Keeping track of a patient's consult needs and results is also a great way to provide added value to your role as a medical student. Most patients will have many consulting services. Some common consults to look out for are speech language pathology (diet recommendations), physical and occupational therapy (mobility and disposition recommendations), and other medical/surgical specialists managing specific organ system issues (neurology, nephrology, etc). Helping to keep track of these consults and providing the team with the recommendations allows the student to contribute to better outcomes for patients and enhance understanding how each contributes to the team approach.

Pain control is another common issue for CTICU patients. Most patients are on both scheduled and as needed regimen for pain control. The “sweet spot” in ICU pain management is the balance between enough medication to allow patients to inhale deeply, cough, and move in the bed but not so much that patients are lethargic or unable to stay awake during daylight hours. Monitoring patient pain levels and relaying them to the team to adjust pain control is an important role for medical students. Most pain regiments are multimodal and change over time; becoming familiar with the basics of pain management at your institution is important.

Most often ventilator settings begin with tidal volumes at 0.7 mL/kg and a positive end-expiratory pressure of around 5 cmH₂O and support is titrated to achieve optimal saturations and ventilation (CO₂). Keep in mind that, in many circumstances, lower tidal volumes and reduced airway pressures should be the goal as lung-protecting measures when using artificial ventilation; discuss lung-protective strategies with ICU staff, residents, and attendings to ensure you understand and can manage ventilator settings. Patients can be considered for extubation once they meet criteria for spontaneous breathing (see the section “Extubation Considerations”). Many use ventilator criteria, like rapid shallow breathing index, respiratory rate/tidal volume <100, negative inspiratory force >20 cmH₂O, tidal volume >5 mL/kg, vital capacity 10 mL/kg, respiratory rate <30 breaths per minute, but it is also important to assess the patient clinically: are they able to protect their airway? There is no substitute for clinical assessment.

There are many complications that can happen in the CTICU or intraoperatively before a patient arrives. Understanding why these occur and the implications to patient management should be the goal for medical students in the ICU. In short, learn to recognize the most common complications and know what the response should be. Arrythmias, acute kidney injury, reopening for cardiac tamponade, pneumonia, and mediastinitis are some of common complications after cardiac surgery and being familiar with this subset prior to beginning a rotation might allow further learning opportunities for an interested student.^,