Critical Care Scenarios

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We discuss head and neck surgery with Dr. Alexandra Kejner, otolaryngologist at the Medical University of South Carolina specializing in transoral robotic surgery, reconstructive surgery including microvascular free tissue transfer, salivary neoplasms, and sialoendoscopic procedures.

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Takeaway lessons

1. Robotics has enabled much less invasive approaches to many head and neck procedures.
2. Major airway procedures create edema, and there is always risk for bleeding, so patients often remain intubated overnight.
3. The other common ICU indication is a free flap, a portion of tissue (potentially including skin, subcutaneous tissue, muscle, even bone) removed from a remote site and transplanted into the head and neck area, with vessels anastomosed. These are at risk of failure and require close monitoring.
4. Most of these procedures will involve placing a tracheostomy, and potentially a PEG (or NG). This facilitates both surgical access and early recovery.
5. Tumors are superficially resected with adequate margins, then reconstruction begins. Meanwhile, exposure of deeper structures and deeper resection occur, which may involve a jig to guide the removal (prepared in advance from imaging), and a matching cut to prepare the flap tissue. Lymph nodes are removed en bloc. Then the flap is transplanted and vessels anastomosed (at least one robust artery and vein), using microsurgery and teeny sutures (often 8-0 nylon).
6. As a supplement to the clinical exam, an implantable Doppler monitor is occasionally left in place to augment post-op monitoring of perfusion, as well as sometimes a Vioptix near-infrared spectroscopy device which performs real-time tissue oximetry.
7. On POD 0-1, hourly nursing monitoring of the flap is usually needed, with periodic provider checks. Changes in the exam (swelling, turgor, cap refill, color), signal, or bleeding may require return to the OR for revision. A single ICU night is the norm, although comorbidities are common and may require a longer stay if the stress of surgery unmasks other problems.
8. Laryngectomy may be performed, involving removal of the larynx (voice box), leaving a blind pouch; the lungs no longer connect to the upper airway in this case, and the entire team should be aware of this anatomy, as the patient cannot be intubated or their airway otherwise managed from above.
9. Most flaps will be on a baby aspirin and enoxaparin, but occasionally may use a heparin drip.
10. Most will receive three doses of dexamethasone, both to reduce edema and to treat any adrenal insufficiency.
11. Chlorhexadine or salt water oral rinses are performed to keep the operative site clean.
12. Multimodal pain management is needed for both the oral site and the donor flap site.
13. A drop in the Vioptix signal from the initial post-op reader, neck swelling, or difficulty breathing (dyspnea, hypoxia, etc) all warrant immediate involvement of the surgical team for danger to the airway or the flap. Flaps might also turn purple from venous congestion, sometimes a little later, also a surgical emergency.
14. A questioned flap might be scratched to see if it bleeds (which is good).
15. A patient in shock might need vasopressors, fluid, or to be hypotensive, none of which are great for a flap. A balanced approach is probably best. A low-dose phenylephrine drip may be the most appealing pressor, and vasopressin might be the riskiest. MAP >65 is a minimum, some prefer higher (>80).
16. Intro-operative feeding has been used in some centers due to the prolonged procedure times.
17. Flap failure historically was most often from a venous clot, but this has reduced over time; nowadays it’s often late failures due to a salivary fistula contaminating the area and creating a region of digestion, clot, and breakdown.
18. Surgeons will occasionally request deeper sedation (or even forcing the patient to maintain a specific neck position) to avoid dislodging monitors, disrupting a very delicate anastomosis, etc.
19. A swollen or firm anterior tongue, ooziness in the mouth, or a difficult airway on the initial intubation may lead a surgeon to request delaying extubation.
20. The immediate post-op appearance usually heals into a better eventual aesthetic result. Occasionally measures like prosthetics can be used.

References

1. Vasopressors improve outcomes in autologous free tissue transfer: A systematic review and meta-analysis
2. Postoperative Use of Vasopressors in Head and Neck Microvascular Reconstruction

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We learn about liver transplant with Dr. Meera Gupta, transplant surgeon at the University of Kentucky Healthcare Transplant Center, and surgical director of the Kidney and Pancreas Transplant Program. We discuss eligibility, triage, the peri-operative course, and important post-op complications.

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Takeaway lessons

1. Liver transplant eligibility is based on need, not time on the list. The MELD score (MELD 3 now, including albumin) is used for this, with MELD >9 (historically >15) considered the cutoff for transplant potentially exceeding the risk of not transplanting.
2. Livers can now be placed on warm perfusion pumps, allowing continued viability for much longer. This is mainly used in donors who died from cardiac death, those with high BMI or similar risks for primary non-function (i.e. the transplanted liver never starts working), and longer transport distances or expected operative times.
3. Incision is a large right subcostal incision, extended as needed. The liver hilum is dissected, preserving the feeding vessels. Caval clamping may be tested, then the liver is removed. This anhepatic phase in minimized to <60 minutes, preferably <45 minutes. The new liver is then anastomosed to the portal veins, vena cava, hepatic artery, and the bile duct. Some instability can occur during reperfusion, such as right heart strain, electrolyte abnormalities, or volume shifts.
4. Patients will usually remain intubated post-op, lines in place. Sedation ideally is limited so the patient can rouse and confirm the absence of encephalopathy. Systolic BP is closely watched (goal >90), as diastolic BP tends to be low in most liver failure patients. Hepatopulmonary patients can rest on the vent a little longer and are expected to remain on oxygen for the time being. Patients can be fed once extubated and stable.
5. High-dose steroids are loaded up front and then tapered, and oral immunosuppression initiated soon after.
6. Some AKI is common. Colloid like albumin is favored early.
7. Chronic thrombocytopenia is common and is monitored to determine when DVT prophylaxis can be started. Platelets >20k are targeted.
8. If INR >2, vitamin K is given empirically. FFP is usually not given prophylactically. Bleeding is usually considered a little preferable to clotting, in terms of ease of treatment.
9. A liver duplex is performed in the first 24 hours to ensure the new vascular supply is patent.

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We learn about pancreaticoduodenectomy (the Whipple) with Michael Cavnar (@DrMikeCavnar), surgical oncologist at University of Kentucky, with a fellowship in Complex General Surgical Oncology from Sloan Kettering. He specializes in GI surgical oncology (liver, pancreas, stomach, etc), with ongoing research in GI stromal tumors and hepatic artery infusion pump chemotherapy.

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Takeaway lessons

1. The Whipple involves an aggressive resection and reconstruction of pancreatic head tumors. Along with the head of the pancreas, the entire duodenum, the bile duct (up to near the entry of the cystic duct), the gallbladder, and usually the distal third of the stomach, along with the nearby lymph nodes, are all removed. There are then anastomoses at the small intestine, the bile duct, and the stomach.
2. The pylorus of the stomach is generally removed, but can be left in a pylorus-sparing Whipple. The benefit of this is not well-established.
3. It is almost always done for malignancy (or occasionally for other conditions like pre-malignant changes or pancreatitis with stricture). Mortality in high-volume centers is a few percent, and usually involves deaths in the first 90 days due to various complications more than death in the OR.
4. Hypotension in the first 24 hours is a poor sign, as it may lead to bowel ischemia, portal vein thrombosis, anastomotic ischemia, or other injuries to vulnerable areas. If getting behind on hemodynamics, consider holding an epidural if present.
5. NG tubes are often placed to around 55 cm. They should not be advanced or replaced by the ICU staff, as the stomach has been shortened, and advancing the tube may traumatize the anastomosis. Bilious gastric drainage is normal in anyone with post-Whipple anatomy. Patients will generally remain NPO for several days.
6. Patients will emerge with 1-2 surgical drains. Output should be serosanguinous (sparsely bloody at most), less than 200ml/hr or so. It may occasionally be lymphatic (clear to lightly serosanguinous), which can be somewhat higher volume. Output should not be bilious or feculent.
7. Early bleeding requiring surgical take-back is uncommon and usually obvious in the drains, unless they clot, which can occur. A pancreatic leak can also dribble onto the stump of the gastroduodenal artery, causing erosion, and subsequent bleeding usually tracks back up into the bowel lumen and hence GI bleeding.
8. Respiratory distress can be treated with oxygen or high-flow nasal cannula, but positive pressure (eg. BiPAP) should be used with caution and consultation with the surgical team, particularly within the first two weeks post-op, as aerophagy can apply pressure to the bowel anastomosis.
9. A leaking pancreatic anastomosis causing fistula will tend to marinate the gastroduodenal artery’s anastomosis in pancreatic juices, creating a pseudoaneurysm; this can be managed early before it turns into massive hemorrhage. Any streak of fresh blood in the drainage should be considered a sentinel marker of this and immediately evaluated, usually involving CTA or pancreas-protocol CT. The treatment of choice is IR embolization and stent, not open repair.
10. Glucose control in diabetics will usually be worse post-operatively, both due to stress and due to removing a portion of the pancreas. SGLT inhibitors can cause strange metabolic effects as well if not fully washed out.
11. Exocrine pancreatic insufficiency can be discovered once feeding begins, usually manifesting as diarrhea (steatorrhea), and can be treated with pancreatic enzyme supplements.
12. A proton pump inhibitor should generally be used post-operatively.