Anesth Analg 2003;97:981-983
© 2003 International Anesthesia Research Society
CARDIOVASCULAR ANESTHESIA
An Alternative Anesthetic Technique for the Morbidly Obese Patient Undergoing Endovascular Repair of an Abdominal Aortic Aneurysm
Maurice Lippmann, MD*,
Sonny Rubin, MD*,
Richard Ginsburg, MD*,
Rodney A. White, MD ,
Jason Lee, MD,
James Lee, MD, and
Ihab Aziz, MD
Depatrments of *Anesthesiology and
Surgery, Harbor-UCLA Medical Center, Torrance, California
Address correspondence and reprint requests to Maurice Lippmann, MD, Professor of Anesthesiology, Harbor-UCLA Medical Center, Department of Anesthesiology, 1000 W. Carson Street, Box 10, Torrance, CA 90509. Address email to smaddox{at}dhs.co.la.ca.us
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Abstract
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Abdominal aortic aneurysms have been treated by open operative repair for many years. A frequent rate of morbidity is associated with the natural history of abdominal aortic aneurysms in combination with open surgical repair. Recently a new technique that is less surgically invasive has been developed as an alternative to open repair. The present case report outlines a less invasive anesthetic technique for the morbidly obese patient.
IMPLICATIONS: This case report discusses a minimally invasive anesthetic approach towards the morbidly obese patient undergoing endovascular abdominal aortic aneurysm repair. It demonstrates a safe and cost-effective means of managing a patient with numerous comorbidities. We also discuss an anesthetic/surgical approach on how to provide maximum analgesia with minimal anesthesia.
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Introduction
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This patient was a 53-yr-old morbidly obese male, 150 cm, 165 kg, with a body mass index of 73.3. He was incidentally found to have a 6.5-cm abdominal aortic aneurysm (AAA) while undergoing a routine computed tomography scan for a history of kidney stones. The patient was subsequently followed for some time because of his enlarging aneurysm, but he was not considered to be an operative candidate because of his morbid obesity. He was not considered for endovascular repair because the aortic neck was approximately 30 mm in diameter and there is no available Food and Drug Administration-approved endovascular prosthesis for necks larger than 26 mm. After further review of the spiral computed tomography scan and discussion of the options for endoluminal repair, the patient opted for an attempted endovascular procedure with the Talent Endoluminal stent graft. Because this prosthesis does not have Food and Drug Administration approval, the patient was treated on a compassionate-use basis approved by the IRB for this disease.
On the preoperative anesthetic consultation, the patient had a past medical history of kidney stones, degenerative disk disease of the lumbar spine, chronic obstructive pulmonary disease, sleep apnea, coronary angioplasty with stent placement in 1998, and type 2 diabetes mellitus. He had no known drug allergies, and medicines consisted of glucopahge 500 mg once a day (qd), atenolol (50 mg qd), spironolactone (25 mg qd), montelukast sodium (10 mg qd), roficoxin (25 mg qd), fluticasone propionate (4 puffs qd), salmeterol (2 puffs qd), and ipratropium bromide as needed (PRN).
The patient was a heavy smoker with a 90 pack-year history. On review of systems, the patient complained of bilateral leg weakness with intermittent claudication while walking 2–3 blocks. On physical examination, the patient was morbidly obese with an enlarged pannus extending over both groins. There was evidence of +1 pitting edema of the lower extremities bilaterally; otherwise the physical examination was unremarkable. Electrocardiogram displayed normal sinus rhythm with a first-degree atrioventricular block, and chest radiograph showed evidence of cardiomegaly with right-sided prominent hilar adenopathy. Baseline arterial blood gas results were pHa 7.32, PaCO2 60 mm Hg, PaO2 93 mm Hg, bicarbonate 35, and SaO2 97% while breathing oxygen via a 3-L nasal cannula.
The patient was categorized as an ASA physical status IV, and proceeded to the operating room (OR) with the intent to institute a monitored anesthetic care (MAC)/local technique. The patient was too large to be accommodated on a usual OR table because of his large body mass. A special carbon fiber table was used and supported with an additional table beneath the inferior aspect so that the table would tolerate the patient’s weight. It is essential to bear in mind that the patient needed to be positioned so that fluoroscopy could easily be adjusted frequently because prolonged imaging is a vital component of this type of surgical procedure. The International Surgical System fluoroscopy system was not able to penetrate the patient’s pannus adequately. To ensure adequate fluoroscopic penetration, a Phillips C arm was also used. It was also of vital importance to ensure the patient’s stability on the OR table to prevent his falling off, as frequent rotations are usually necessary. It was somewhat difficult to accomplish this comfortably, as the usual restraint belt did not fit around the patient. Securing the patient was eventually achieved using two straps together and fastening them around the lower legs. Once secured, the team decided to elevate the pannus using 4-in wide adhesive tape at a distance high enough to avoid the operative field and thereby ensure sterility and then prepare the patient in the usual manner (Figs. 1–3). This was a source of concern for us as, although it appeared wide enough, we wanted it to be tight enough to hold the pannus up for the duration of the procedure and simultaneously avoid pressure necrotic damage to the skin. Once surgical access to the femoral arteries was secured, the team would release the tightness of the tape without completely releasing the pannus.
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Figure 3. Cloth adhesive tape holding pannus away from groin area and attached to side of operating table.
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The patient had 2 18-gauge IV lines and an 18-gauge right radial arterial line inserted. Basic monitors consisted of electrocardiogram, pulse oximeter, invasive arterial blood pressure, skin temperature, and end-tidal CO2 tracing via an oxygen face mask. Before incision, the patient received a sole narcotic anesthetic with fentanyl 200 µg IV titrated over 30 min. This enabled the patient to tolerate the local infiltration of his groins performed by the surgeons. Local infiltration of the surgical site consisted of lidocaine 0.5% without epinephrine. Over the course of 6 h, a titrated total of 155 mL of lidocaine 0.5% was infiltrated at the site of incision. In conjunction with local infiltration, another 200 µg of fentanyl IV was administered to meet the patient’s analgesic requirement. Midazolam 2 mg IV was coadministered to aid in anxiolysis during the procedure. Total IV anesthetic requirements consisted of fentanyl 400 µg and midazolam 2 mg. The patient’s fluid requirements included Plasmalyte as the crystalloid of choice, with a total of 4500 mL infused. This was according to the patient’s blood loss, urine output, and maintenance fluids. Blood loss consisted of 1000 mL, of which 900 mL was collected in an autovacuum container and infused back to the patient. The patient never required colloid, packed red blood cells, or coagulation products during the procedure. Urine output remained constant at 140 mL/h over 6 h. Subsequently, the patient was transferred to the intensive care unit in stable condition and monitored overnight for further observation. The entire hospital course was uneventful, and the patient was discharged home 2 days later.
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Discussion
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Endovascular stent grafts are performed more frequently for the repair of AAA. However, patients are usually preselected for the successful outcome of such procedures. These procedures are usually performed under general, epidural (1), or spinal anesthesia. We report here on the anesthetic management of a morbidly obese patient undergoing endovascular stent graft repair of an AAA under local anesthesia with MAC.
The morbidly obese patient needs more team effort than is usually required. Perioperative issues and procedures considered normal and even routine must be re-examined when dealing with the morbidly obese patient for a variety of reasons, and considerations need to be given.
It is of vital importance to ensure the patients stability on the OR table to prevent falling, as frequent rotations are usually necessary. It was somewhat difficult to accomplish this comfortably, as the usual restraint belt did not fit around the patient, and securing the patient was eventually achieved using two straps together and fastening them around the lower legs. This was potentially a problem as securing the legs in this fashion could potentially impede vascular access, especially if conversion to a more open procedure was required.
At no time did we use or require central venous access or placement of a Swan-Ganz catheter. In the unlikely event of a rupture, central venous access would have immediately been established in the conversion to an open surgical repair. Over the course of the procedure, narcotic was titrated towards the patient’s requirements and comfort level. This titrated technique requires a team approach with the surgeon instituting local anesthetic simultaneously to decrease narcotic requirement. The synergistic effect minimizes the amount of administered narcotic and enables adequate communication between the patient and the anesthesiologist. Minimal amounts of benzodiazepines are used to prevent respiratory/cardiovascular side effects in the patient with comorbidities ranging from severe chronic obstructive pulmonary disease to a history of myocardial infarction. In addition, the patient’s cognitive function is better preserved and there is less agitation. After extensive evaluation of his airway by the anesthesia team, it was deemed an acceptable grade by the Mallampati criteria should conversion to a general anesthetic be necessary. Securing the patient’s airway was acceptable in his case. Equipment for managing the difficult airway was readily available, including a fiberoptic bronchoscope and a number 4 laryngeal mask airway.
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Conclusion
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We report here how small incremental IV narcotic doses can be used in conjunction with local anesthesia administered by the surgeons in a morbidly obese patient with numerous comorbidities undergoing endovascular stent grafting of an AAA. We also emphasize a minimally invasive approach with small doses of narcotic/benzodiazepines to help achieve a successful outcome in a complicated case that required special anesthetic, surgical, and nursing maneuvers.
The MAC with local technique (2) enables the anesthesiologist to avoid more invasive techniques used in the past (e.g., spinal, epidural, general anesthesia). In addition, it alleviates the need for invasive monitoring (e.g., central venous catheterization and Swan-Ganz catheter insertion). This combined technique enables the patient to maintain his airway without assistance. The ability to converse with the patient aids in the early detection of an unlikely aneurysm rupture, myocardial infarction, or cerebral vascular accident. It allowed our patient to ambulate earlier and consume nutrition within several hours postprocedure. His hospital stay was minimal (2 days) versus 5–7 days in an intensive care unit, plus additional days of hospitalization for an open surgical procedure. This, in turn, reduced hospital costs, postoperative complications, and length of hospital stay. This new surgical/anesthetic technique is especially useful and recommended in the geriatric patient population with multiple comorbidities where morbidity and mortality are most frequent (2–4).
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References
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- Cao P, Zannetti S, Parlani G, et al. Epidural anesthesia reduces length of hospitalization after endoluminal abdominal aortic aneurysm repair. J Vasc Surg 1999; 4: 651–7.
- Lippmann M, White R, Walot I, et al. "Fast Track" anesthesia minimizes hospital stay after abdominal and thoracic endovascular aortic aneurysm repair. Anesthesiology 2001; 95: A30.
- Parodi J, Palmaz J, Barone H. Transfemoral intraluminal graft implantation for abdominal aortic aneurysms. Ann Vasc Surg 1991; 5: 491–9.[Medline]
- Kahn RA, Moskowitz DM. Endovascular aortic repair. J Cardiothorac Vasc Surg 2002; 16: 218.[Web of Science][Medline]
Accepted for publication May 30, 2003.
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Abstract
Introduction
