Successful Anesthetic Management of Rigid Bronchoscopy-Guided Percutaneous Tracheostomy in a Patient with Morbid Obesity

| March 18, 2013

This ongoing column is authored by members of the International Society for the Perioperative Care of the Obese Patient (ISPCOP), an organization dedicated to the bariatric patient.

Column Editor: Stephanie B. Jones, MD

This month’s installment by: Nicholas Wasson, MD, and Stephanie B. Jones, MD

Dr. Nicholas Wasson is a Clinical Fellow, Anaesthesia, Harvard Medical School, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts. Dr. Stephanie B. Jones is Associate Professor, Anaesthesia, Harvard Medical School, Department of Anesthesia, Critical Care and Pain Medicine, Beth Israel Deaconess Medical Center, Boston, Massachusetts.

Funding: No funding was provided.

Disclosures: The authors do not have any conflicts on interest relevant to the content of this article.

We discuss a case involving a 66 year old severely morbidly obese female (148 kg, BMI 60 kg/m2) with respiratory failure and significant co-morbid disease undergoing rigid bronchoscopic guidance for percutaneous tracheostomy. To date, there is limited published data on administration of an anesthetic for this procedure. We outline a strategy for successful anesthetic management of rigid bronchoscopy, jet ventilation, and safe and efficient transportation of the critically ill morbidly obese patient.

Bariatric Times
. 2013;10(3):26–28.

As the obesity epidemic in the United States continues to expand, there is an increasing number of patients with morbid obesity admitted to an intensive care setting. One retrospective study has quoted the incidence of morbid obesity (BMI≥40 kg/m[2]) as high as 14 cases per 1000 medical intensive care unit (ICU) admissions per year (1994–2000).[1] This is likely an understatement, given this study does not include surgical patients. A recent study from the RAND Corporation estimates that 6.6 percent of the United States population, or approximately 15.5 million people have a BMI≥40kg/m[2].[2] Quite often, this condition is associated with significant comorbidities, including type 2 diabetes mellitus (T2DM), hypertension, coronary artery disease, congestive heart failure, stroke, gallbladder disease, asthma, and various types of cancer.[3]

When admitted to the ICU, these patients often have signficantly higher rates of mortality and signficant complications compared with nonobese patients,[4] and often require prolonged mechanical ventilation.[1] Tracheostomy may be indicated, and currently there is a general trend toward percutaneous versus open tracheostomy due to lower rates of complications and costs.[5] Obesity is often considered a relative contraindication to percutaneous tracheostomy, however, several studies have evaluated this procedure and have deemed it safe to perform in the patient with morbid obesity.[6,7]

Rigid bronchoscopy has been described as a useful method for guidance of percutaneous tracheostomy. It provides excellent visualization of airway structures, adequate oxygenation and ventilation, constant visual guidence, and a secure airway, particularly in patients with a known history of diffcult airway[8,9] as may be seen in the morbidly obese patient population. The thoracic surgery and interventional pulmonary divisions at Beth Israel Deaconess Medical Center, Boston, Massachusetts, have significant experience in performing this procedure in a wide variety of high-risk patients.[9] There is currently limited published data specific to the anesthetic care of the patient with obesity for percutaneous tracheostomy. We present here a description of our anesthetic management of a critically ill patient with severe morbid obesity presenting for rigid bronchoscopic guidance for percutaneous tracheostomy.

Case Description
Our patient, a 66-year old woman with morbid obesity (148kg, BMI 60kg/m2), initially presented to the ICU in respiratory failure requiring emergent intubation. She had significant comorbid disease, including the following: 1) chronic obstructive pulmonary disease (COPD) for which she was on 3 L home oxygen at baseline; 2) obesity hypoventilation syndrome; 3) obstructive sleep apnea (OSA) for which she was on continuous positive airway pressure (CPAP); and 4) recurrent aspiration pneumonia. She had a history of heavy smoking and atrial fibrillation. She was unable to wean from mechanical ventilation after a prolonged intubation period of three weeks, and was scheduled to undergo a percutaneous tracheostomy with rigid brochoscopic guidance with our interventional pulmonary service.

Transportation of the patient presented the first challenge. In the ICU, she was cared for on a special bariatric bed designed to aid turning of pateints with morbid obesity, however, since this specific type of bed is very difficult to transport in the standard elevator and into operating rooms due to its bulk and relatively poor mobility, we decided to transport the patient to the operating room on a stretcher suitable for her weight with standard monitoring equipment. Following sedation with midazolam 2mg and fentanyl 100mcg, and neuromuscular blockade with rocuronium 30mg, transport from her bed to the stretcher was accomplished with an overhead lifting system. She was lifted from her ICU bed to a stretcher, upon which an air-assisted lateral patient transfer system mattress was in place, and transported to the operating room with standard monitors. Inflation of the air mattress allowed for easy transfer to and from the operating room table despite the patient’s weight.

Once positioned on the operating table and after appropriate American Society of Anesthesiologists (ASA) monitors were placed, general anesthesia was induced via her indwelling endotracheal tube with a mixture of sevoflurane and oxygen. Neuromuscular blockade was achieved with intravenous rocuronium. Prior to placement of the rigid bronchoscope, the patient was ventilated with 100% oxygen, and transitioned to a total intravenous anesthetic (TIVA) with infusions of propofol 40 to 60mcg/kg/minute and remifentanil 0.01 to 0.04mcg/kg/minute. Upon initiation of the TIVA, the patient became mildly hypotensive to a blood pressure of 80/60. This was treated with a phenylephrine infusion, and she remained hemodynamically stable for the remainder of the procedure.

The head of the bed was then declined at a 45-degree angle, the rigid bronchoscope was introduced into the glottis and the endotracheal tube was removed (Figures 1-3). Jet ventilation was initiated via the rigid bronchoscope with the automatic electronic jet ventilator (Acutronic Monsoon). Despite increasing frequency and pressure settings, the patient quickly desaturated to an SaO2 of 60%. This was communicated to the bronchoscopist, and placement of the rigid bronchoscope in the trachea was confirmed. We immediately converted to manual hand jet ventilation (Anesthesia Associates, Inc. #00-325), with return of her O2 saturation to >94% (Figure 5). Local anesthesia with lidocaine 1% with epinephrine 1:200,000 was injected prior to incision in order to minimize bleeding. Percutaneous dilational tracheostomy was performed under direct visualization via the rigid bronchoscope. (Figure 5, Figures 6–7, Figures 8–9, and Figures 10–12). Once the procedure was completed and confirmation of appropriate tracheostomy tube postioning was obtained again by direct visualization, the anesthesia breathing circuit was attached to the trachestomy tube. ETCO2 and bilateral breath sounds were confirmed. The rigid bronchoscope was removed, and the remifentanil infusion discontinued. The patient was then transferred back to the stretcher, again with the aid of the air-mattress and was transported to the ICU with proper monitoring on a propofol infusion in stable condition. She was eventually discharged to a long-term, extended-care facility.

This case demonstrates something which is becoming more commonplace in our profession: the transport and management of the critically ill patient with morbid obesity. Upon initial evaluation of this patient, it became evident that the use of the special purpose bariatric bed designed for the patient with morbid obesity was not suitable for transport. The over-head lifting system (Likorall R2R), which is standard equipment in our ICU rooms, allows not only for the turning and routine daily care of the critically ill patient with morbid obesity, but also allows for the lateral transfer of such patients. In addition, the use of the air-assisted lateral transfer system mattress (HoverTech HoverMatt) for transfer of the patient to and from the operating room table greatly reduced the number of staff necessary for the transfer and amount of weight, which had to be lifted by each staff member. Back pain is the leading cause of occupational disability in the world.10 Healthcare workers in particular rank highly amongst the top occupations with disabling back injuries primarily from lifting patients, and back injuries may be the largest contributor to the current nursing shortage.11 We found that this method of transport from the ICU to the operating room and back required virtually no heavy lifting on the part of the staff members in transport of this patient.

The next challenge involved removal of the endotracheal tube and passage of the rigid bronchoscope with the initiation of jet ventilation. This required close communication with the bronchoscopist. Once the team is in position with the rigid bronchoscope, there is a narrow window of time during which the endotracheal tube is removed and rigid bronchoscope placed before the patient may desaturate. This was rapidly accomplished in our case, but despite efforts to automatically jet ventilate and direct visual confirmation of the rigid bronchoscope, the patient’s oxygen saturation rapidly decreased. We found that conversion to manual hand jet ventilation rapidly improved the patient’s oxygenation. It is standard practice to have the manual jet ventilator readily available as a backup to the automatic jet ventilator.The reason for the desaturation could likely be that the settings used on our electronic jet ventilator (Psi, FiO2, ventilation frequency, inspiration duration) were inadequate and were not increased high enough to maintain adequate oxygenation and ventilation in the presence of significantly decreased respiratory compliance. It is difficult to predict the resulting parameters of gas flow, tidal volume, and actual airway pressure required despite the settings on the electronic jet ventilator, largely due to unavoidable air entrainment as well as the driving pressure required for lung insufflation. This pressure may be anywhere from 20 to 50 times higher than conventional ventilation due to higher resistance of the jet outlet.12 We believe that manual jet ventilation is more rapidly adaptable in a setting of acute oxygen desaturation as it allows for rapid changes in pressure and inspiratory time and the ability to increase or decrease the ventilation frequency in lieu of having to adjust multiple settings on the electronic jet ventilator.
For maintenance of general anesthesia, we routinely use propofol and remifentanil infusions during rigid bronchoscopy. This allows for adequate depth of anesthesia, pain control, and rapid emergence should it be required following the procedure. We achieve muscle relaxation with either succinylcholine or nondepolarizing neuromuscular blocking agents. This technique allows for the most ideal surgical conditions possible to perform both the rigid bronchoscopy and the percutaneous tracheostomy.

In conclusion, with proper planning and close communication with an experienced bronchoscopist, we believe that dilational percutaneous tracheostomy under rigid bronchoscopic guidance can be accomplished safely and effectively in the critically ill patient with morbid obesity.

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Category: Anesthetic Aspects of Bariatric Surgery, Past Articles

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