Delivering continuous positive airway pressure (CPAP) with novel nasal PAP mask assembly is an effective technique for improving safety in patients receiving an interscalene block and sedation for shoulder arthroscopy, new research suggests.
Some people may be given a sedative after a regional peripheral nerve block. Desaturation commonly occurs in patients receiving moderate to deep sedation, according to researchers from Rutgers Robert Wood Johnson Medical School, in Piscataway Township, N.J. Supplemental oxygen supplied through a nasal cannula is often insufficient for maintaining adequate oxygenation.
The original technically simple and effective (TSE) mask, a 12-by-12–inch plastic sheet used to cover a patient’s nose and mouth, has been shown to increase oxygenation during upper endoscopy, providing a fraction of inspired oxygen of 40% to 60% with oxygen flows of 4 L per minute via nasal cannula (Anesthesiology 2005;102:484). The researchers presented a case study showing the efficacy of the nasal TSE-PAP mask assembly for maintaining oxygen saturation in a patient with autonomic neuropathy under regional anesthesia supplemented by sedation.
“What we did in this case is take an infant mask attached over the patient’s nose with head straps and connect it to a long breathing circuit with continuous positive airway pressure via the anesthesia machine,” said Dennis Warfield Jr., MD, lead study author and second-year anesthesia resident at the institution. “This enables the airway to maintain patency and provide continuous oxygenation.”
The patient was a 68-year-old woman who presented for arthroscopic incision and drainage for an infected right shoulder after two failed rotator cuff repairs. Autonomic neuropathy, which occurs when nerves that control involuntary functions are damaged, is commonly related to having a prolonged history of diabetes, according to Dr. Warfield.
“However, in our patient it was a sequelae of a major diarrheal illness,” he said. “She came to us after two failed rotator cuff repairs and unsuccessful medical management and surgical treatment to try to relieve the autonomic neuropathy.”
The patient reported poor response to antihypertensive treatment due to profound hypotension, and had two failed medullary decompression surgeries. Her preoperative vital signs on the day of surgery included a blood pressure of 226/131 mm Hg and heart rate of 134 beats per minute.
“What we decided to do was avoid general anesthesia in an attempt to circumvent extreme lability in blood pressure,” Dr. Warfield said. “We decided to conduct regional anesthesia with a one-shot interscalene block in addition to sedation.”
The patient was placed in the sitting position. The researchers administered an ultrasound-guided right interscalene one-shot block of 30 cc of 2% lidocaine hydrochloride and epinephrine 1:200,000 injection. The patient also received 2 mg of midazolam and 100 mcg of fentanyl before the block, and was given the same doses at the beginning of the procedure.
The researchers secured the TSE-PAP mask assembly over the patient’s nose with head straps and connected it to the anesthesia machine, delivering 6 cm of water CPAP with 2 L of oxygen per minute and 2 L of nitrous oxide per minute.
The patient maintained spontaneous respiration and had 100% oxygen saturation throughout the case, the researchers reported.
“There were no significant swings in blood pressure or heart rate,” Dr. Warfield said. “She was able to maintain her oxygen saturation throughout the case and was discharged later on the same day.”
He noted that the noninvasive technique’s low cost is another benefit to using it to improve oxygenation and safety in sedated patients.
“It’s a very cheap alternative, and the equipment that we used is found in the majority of today’s operating rooms,” he said.
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