Chapter 21
Maintenance of Anesthesia

Perfecting the maintenance phase of your anesthetic comes with time, repetition, and experience. Some cases lend themselves to a hemodynamic “sweet spot,” wherein once you achieve an adequate plane of anesthesia, you can keep patients stable through fluctuations in surgical stimulation. But more often, your skills will be tested in managing those ups and downs in real time.

The first time you’re left alone in the OR will likely be during the maintenance phase of the anesthetic. It can feel overwhelming at first. You might wonder, should I just sit tight and wait for something to happen? Should I deepen the anesthetic in case the stimulation level suddenly increases? Should I re-paralyze? Should I start preparing for the next case?

It’s normal to feel uncertain. The key is to develop a mental checklist or a framework for periodically assessing the safety and adequacy of your anesthetic. Both beginners and experienced anesthetists rely on these internal checklists, sometimes consciously and sometimes instinctively. When in doubt, focus on building your own internal workflow for this phase; the following sections will help guide your attention and keep you proactive rather than reactive.

Have a Contingency Plan

Regardless of the case, be ready to pivot from a routine anesthetic to an emergency resuscitation. As discussed in Part 1, the most common intraoperative emergencies involve either respiratory compromise, such as loss of airway or hypoxemia, or significant bleeding. Be prepared for either of these events. Preparation always starts with organization and situational awareness:

Organize Your Anesthetic Layout

If these fundamentals are in place, you’re equipped for whatever the case brings:

Take stock of IV lines: Organized and flowing freely, with no resistance or kinking. It’s critical to assess functionality throughout the case.
Address tangled wires: Clutter can delay critical interventions.
Remove nonessential items: Keep them out of the workspace to reduce clutter in an emergency.
Emergency drugs: Have propofol, paralytics, and pressors available at all times. For pediatric patients, include atropine and succinylcholine.
Release the pop-off valve when not in use: To prevent overdistention when taking the patient off the vent.
Confirm all aspects of the ventilation system are appropriately secured: More in further sections.
Keep resuscitation supplies within your line of sight: Know where to access the Ambu bag, supplemental oxygen, crash cart, and supplies for rapid infusion or transfusion.
Communication: Have your attending’s or supervisor’s number/pager loaded and ready for immediate contact.
Anticipation: Be aware of what critical events may occur during the case and whether they’ve already happened. If handing off the patient, clearly communicate these possibilities.
Have lab values handy: Hemoglobin, platelets, coagulation profile, creatinine, and any abnormal values that may be relevant to the case.
Be mindful of fluid goals for the case. Avoid leaving fluid running open and unattended. With large-bore IVs, it’s easy to deliver fluid too rapidly. Stay aware.
Confirm stopcock positions are correct: Infusions should be running as expected, and not dripping onto the floor from a loose connection.
Have a plan for unexpected bleeding: Be aware of type + screen status, location of blood tubing, extra IV supplies, blood bank contact information, and recent labs.
Keep an eye on baseline peak airway pressures early in the case, so you can keep track of any gradual or sudden changes throughout the case.

Providing Optimal Surgical Conditions

Optimal surgical conditions require a plane of anesthesia that prevents movement that would impact the surgical field. This varies depending on the case, with some cases being more amenable to patient movement and others requiring pristine levels of paralysis. Ensuring proper levels of neuromuscular blockade is a critical part of the maintenance of your anesthetic.

Unexpected patient movement can quickly derail your sense of control. Neuromuscular monitoring with train-of-four (TOF) helps distinguish no paralysis from mild paralysis, but it’s unreliable for gauging surgical readiness. This is especially true as surgeons increasingly expect deep blockade in the era of sugammadex and robotic surgery. “Spot checks” of TOF often mislead, particularly in patients with cachexia, advanced age, or poor access to limbs. Zero twitches may be providing false reassurance. Decide early whether paralysis is needed and to what depth. For rocuronium, I recommend to re-dose as soon as post-tetanic twitches return. This is because recovery from rocuronium follows a sigmoid curve, with rapid acceleration. With nonreversible agents like cisatracurium, my strategy is not as aggressive. I would recommend to re-dose only after full twitch recovery to avoid over-paralysis. Being proactive, not reactive, keeps the case smooth and builds trust.

For any paralyzed patient, ensure adequate anesthetic depth—typically at least 0.7 MAC of volatile, adjusted for age, with BIS as a secondary guide. Under TIVA, vigilance is critical since there’s no true “MAC equivalent” for propofol, and awareness risk is highest. Discuss infusion targets with your attending rather than relying on online conversions, which are speculative at best.

Conversely, when paralysis is contraindicated (e.g., thyroidectomy with local dissection), maintain a deeper anesthetic plane—around 1.0 MAC—and support hemodynamics as needed. Light anesthesia in cases involving the head and neck region is unsafe territory as a trainee.

Maintaining Stable Hemodynamics

Maintaining stable hemodynamics during surgery is important for a number of reasons. First, it is safe for the patient. Studies have consistently demonstrated that even short periods of MAP <55 are associated with postoperative complications. Surely there are some confounding factors, but it’s common sense that avoiding hypotension is good clinical practice. It’s also a good systems-based practice. When postoperative complications arise, consulting teams often scrutinize intraoperative blood pressures as potential contributors to issues like AKI or stroke. This can overstate the influence of a relatively short anesthetic period, but it still underscores the importance of maintaining a clean, consistent anesthetic record that doesn’t draw attention for avoidable variability.

Smooth blood pressure management is also a visible sign of control. Just as neatly aligned sutures reflect a surgeon’s precision, a stable blood pressure tracing reflects yours. It’s often the only aspect of your work that both the surgical and postoperative teams can see.

When facing a hemodynamic aberrancy (hypertension, hypotension), take a methodologic and thoughtful approach before reflexively treating.

Is this due to your anesthetic?
Is it a result of surgical stimulation?
Or is it intrinsic to the patient’s chronic or acute disease process?

A mentor once shared a valuable guideline: “Give anesthesia drugs for anesthesia reasons, and cardiac drugs for cardiac reasons.”

For example:

Tachycardia from light anesthesia? Treat with more anesthesia.
Tachycardia in a patient with coronary artery disease? Consider beta blockers.
Tachycardia due to sepsis? Accept it, since it may be a necessary compensatory response to maintain cardiac output.

Using such a mindset, you are less likely to engage in a misattribution error. Recognizing the root cause of the clinical symptom is critical to avoid inappropriate interventions.

Here are some examples of misattribution error:

A young patient presenting with a soft tissue abscess is undergoing an incision and drainage under general anesthesia with LMA. He receives repeated boluses of esmolol, labetalol, and metoprolol for tachycardia. The true cause of his tachycardia was light anesthesia and not a primary cardiac event. This misattribution could lead to significant bradycardia when stimulation ceases.
A patient with a pulmonary embolism receives 4 mg of Dilaudid during a cystoscopy, under the mistaken belief that the tachycardia was due to light anesthesia. In this case, the harm is not extravagant, but misattribution and excess opiate administration may significantly prolong emergence.