Anesthesiology, Article

Noninvasive positive pressure ventilation in procedural sedation

Case Report

noninvasive positive pressure ventilation in procedural sedation

Abstract

Maintenance of spontaneous effective ventilations can present unique challenges to emergency physicians directing procedural sedation in patients with underlying anatomic or physiologic upper airway pathology. In a morbidly obese patient requiring electrical cradioversion, use of bilevel positive airway pressure facilitated deep sedation while averting any adverse Respiratory complications. Noninvasive pressure support ventilation may present another emergency department adjunct for difficult procedural sedation cases.

The ability to maintain a patent airway while preserving spontaneous effective respirations is a defining difference between deep sedation and general anesthesia [1]. Compli- ance with this distinction may present a challenge during sedation of patients who experience anatomic airway obstruction secondary to medication related muscle relaxa- tion. The use of noninvasive pressure support ventilation in a morbidly obese individual requiring deep sedation in the emergency department (ED) demonstrates a potential solution to this clinical dilemma.

A 42-year-old man presented to the ED with a complaint of palpitations and shortness of breath. The patient noted that the symptoms began approximately 4 hours before presen- tation and were similar to symptoms he experienced once before when he had an irregular heart beat. He did not know the specific nature of his prior cardiac problem, but noted that he was admitted to the hospital for a fast heart rate for approximately 3 days. Additional questioning revealed that the patient was told he had Sleep apnea and was to use a device to sleep at night, although he never followed up on this recommendation.

The patient was placed on a specialized bariatric stretcher and positioned with the head of the stretcher elevated at 45 degrees. Continuous cardiovascular monitoring was initiated and intravenous access secured.

Physical examination revealed a 5-ft 11-in (180 cm) male weighing a self-reported 450 lb (205 kg) in no-acute distress. Vital signs on presentation were as follows: pulse, 140 beats/ min; respirations, 23 breaths/min; blood pressure, 115 / 87 mm Hg; and pulse oximetry, 98% on room air. Aside from the

pronounced obesity, the only other relevant abnormality noted on examination was a rapid irregularly irregular heart beat. The patient’s cardiac monitor revealed uncontrolled atrial fibrilla- tion, with a rate varying between 110 and 140 beats/min. The arrhythmia was confirmed with a 12-lead electrocardiogram, which, aside from the atrial fibrillation, revealed no Ischemic changes, Conduction abnormalities, or axis deviations.

The initial impression was recent onset atrial fibrillation. Because the symptoms were less than 72 hours in onset, it was determined that the patient was a candidate for immediate rhythm conversion. The large chest diameter of the patient was considered a potential problem for delivery of an effective electrical discharge for direct current cardioversion. As an alternative, chemical cardioversion was attempted with 1 g of procainamide infused over a 1-hour period. After infusion of the procainamide, the patient remained in atrial fibrillation. At this point, it was elected to attempt DC cardioversion, even in the face of the large body habitus. Because of airway concerns and the patient’s history of sleep apnea, he was placed on Bilevel positive airway pressure through a full face mask using a “BiPAP Vision Ventilatory support system” (Respironics, Murry- ville, Pa). The patient was permitted to breath spontaneously with an inspiratory positive airway pressure of 15 cm H2O and an expiratory positive airway pressure of 10 cm H2O with a 50% FiO2. The patient was placed on BiPAP by the ED staff.

Continuous cardiac and Pulse oximetry monitoring along

with fixed interval Blood pressure monitoring were main- tained in place. Although available, continuous nasal capnometery was not used because of the high flow through the BiPAP mask. The patient’s respirations were monitored clinically. Self-adherent monitor-defibrillator pads connected to a Lifepak 20 Defibrillator/Monitor (Medtronics, Minnea- polis, Minn) were placed in the right infraclavicular area and the left lateral chest wall. Deep sedation was achieved with only 100 mg of intravenous propofol. Both the recording nurse and attending emergency physician confirmed the presence of spontaneous respirations corresponding with fluctuations in the BiPAP pressures. The patient maintained a constant oxygen saturation of 100%. A single 320-J biphasic discharge successfully converted the patient to normal sinus rhythm. A repeat electrocardiogram demonstrated normal sinus rhythm with a rate of 60 beats/min and no other noted abnormalities. After the return to normal sinus rhythm, the

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750.e2 Case Report

patient remained on the BiPAP until fully awake approxi- mately 10 minutes after the propofol bolus. He remained in normal sinus rhythm and was discharged to home 2 hours after completion of the procedure.

The patient’s medical records were subsequently obtained from his prior arrhythmia admission. At that time, he was in atrial flutter and was DC cardioverted during a formal electrophysiology evaluation. The summary for this electro- physiology study stated: “Due to prior problems with respiratory distress with even mild anesthesia, the patient was electively intubated before this procedure.” It should be noted that electrophysiologic testing is performed with the patient in the supine position as opposed to the semierect positioning of the patient in the ED.

Procedural sedation and analgesia (PSA) of any type has the potential to produce passive obstruction of the upper airway. Patients with certain neurologic, myopathic, or anatomic abnormalities are at even greater risk for this problem, whereas the presence of airway issues with natural sleep may signal the potential for similar problems with procedural sedation [2-4]. Muscle relaxation can permit posterior displacement of the tongue with occlusion of the upper airway in anatomically susceptible patients, whereas enhanced loss of muscle tone can lead to the same effect in those with neuromuscular problems. Many of the medica- tions used in PSA reproduce the same conditions that lead to airway obstruction in patients with sleep-related pathology. Noninvasive positive pressure ventilation (NPPV) has been used effectively to treat sleep-related airway obstruction from a number of varied causes. Obesity-related sleep apnea may be the most common indication for NPPV, but this technique has been used in patients with upper motor neuron diseases, muscle wasting syndromes, chest wall pathology, and chronic neurologic conditions [4-9]. Despite the success of NPPV in preserving effective ventilation during natural sleep, there has been very little research into its utility in PSA. To our knowledge, the illustrative case presented here is the first report of the use of NPPV for procedural sedation and the only one to apply it to a deeply sedated patient. Two reports have noted the use of NPPV as an adjunct to regional anesthesia but not for procedural sedation. In 1995, Nozaki- Taguchi et al [10] studied the use of continuous positive airway pressure (CPAP) to limit upper airway obstruction during sedation of normal body habitus patients undergoing Spinal anesthesia. In 2005, Reid and Picton [4] reported the use of the patient’s own home CPAP device to help with sedation of

obese patients undergoing regional anesthesia as well.

Very limited options exist for a physician faced with the procedural sedation scenario in this report. The physician might sedate the patient and hope that any obstruction that occurs responds to standard airway opening maneuvers. Alternatively, the physician could electively intubate the patient for the procedure, which would present an entirely different set of challenges. Noninvasive positive pressure ventilation’s ability to preserve airway patency and assist ventilatory efforts provides a third option.

Noninvasive positive pressure ventilation has also been successfully applied to children with neuromuscular related respiratory problems [11,12]. Theoretically, NPPV may be used in at-risk pediatric patients requiring procedural sedation as well.

Emergency physician may be the most comfortable exploring the concept of NPPV-assisted sedation because of their familiarity with the use of CPAP and BiPAP in acutely decompensated patients and their expertise in PSA. At present, more research into the ED application of this approach is warranted in both adult and pediatric patients with variable underlying conditions.

Noninvasive positive pressure ventilation may be con- sidered in preserving effective spontaneous respirations in patients with potential airway obstruction undergoing procedural sedation.

Jason Remick DO Thomas Jefferson University Philadelphia, PA 19107, USA

Alfred Sacchetti MD Gust Bages RN Kristen Delagol RN

Department of Emergency Medicine Our Lady of Lourdes Medical Center

Camden, NJ 08103, USA

E-mail address: [email protected] doi:10.1016/j.ajem.2009.11.010

References

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