Anesthesia management Archives - Page 8 of 20 - Xenon Health

Like other out-of-OR locations, the magnetic resonance imaging (MRI) suite presents unique challenges to the anesthesiologist. Often remote from readily available backup both in terms of equipment and personnel common to the operating room suite, ensuring adequate foresight and preparation is essential to ensuring patient safety. Recent technological advances have facilitated the safe provision of anesthesia services in this setting.

While not all patients require anesthesia for MRI scans, their long duration and the enclosed system of the scanner make sedation helpful for children, developmentally delayed individuals, and claustrophobic or anxious adults to facilitate lying still. For some scans which require breath holds, i.e. for arterial mapping where even the slightest motion can interfere with image acquisition, general anesthesia may be necessary for those too young or unable to cooperate. Newer MRI scanners combine a wider bore with high-field systems to facilitate obese or claustrophobic patients’ comfort in the scanner, as well as decreasing the duration of the scan.

For those requiring some level of sedation for MRI scans, regimens range from anxiolytics such as midazolam, to propofol infusion based regimens, to general anesthesia with volatile gas. With deeper levels of sedation, monitoring airway patency is necessary. Given that the anesthesiologist must monitor the patient from outside the scan room, and the scanner often obscures direct view of the patient, direct visualization of chest rise or misting are ineffective measures. Use of end tidal carbon dioxide is a helpful tool and can be sampled from a nasal cannula or face mask, or from the ventilator circuit by way of mask, LMA or ETT. Often with the current technology this data, along with the patient’s vitals, can be transmitted to a remote monitor accessible to the anesthesiologist and even imported into an electronic medical record. Similarly, MRI-compatible infusion pumps have become advanced enough to be remotely controlled from outside the scan room, so that the level of sedation can be easily titrated.

Airway obstruction is of particular concern given the distance separating the anesthesiologist from the patient. Oral and nasal airways may be employed with deep enough sedation, and advanced airways with general anesthesia are again an option if the concern for airway compromise is high. One study described a prototype of the nasal vestibular airway (NVA) in anesthetized children undergoing MRI. The NVA is a nasal tube connected to an oxygen source and provides continuous positive pressure by means of a pressurized reservoir bag controlled by a valve and pressure gauge. The clinical advantage of this device over those already mentioned has not been formally studied.

Compatibility of devices used in the scan room is of especial concern in MRI anesthesia. All monitors, infusion pumps, ventilators, gas tanks and other equipment should be clearly designated as MRI safe, with no ferromagnetic material (i.e. iron, nickel, cobalt) being allowed beyond the designated boundaries for fear of becoming dangerous projectiles. MRI compatible EKG electrodes and carbon fiber cables should be used to minimize the risk of burns, and coiling of wires should be avoided for the same reason. Similarly only MRI specific pulse oximeters should be used, as they contain heavy fiberoptic cables which do not overheat or coil onto themselves.

Anesthesia and sedation in the MRI suite presents a unique set of challenges to the anesthesiologist. Recent technological advances have improved safety and efficiency in providing patient care in this setting. Like other out-of-OR locations, adequate preparation and thoughtful consideration of environmental factors is of utmost importance.

References

Arthurs, Owen J; Sury, Michael. Anaesthesia or sedation for paediatric MRI: advantages and disadvantages. Current Opinion in Anaesthesiology. 26(4):489-494, August 2013.

Miller, Ronald D. (2015) Procedures Guided by Computed Tomography, Positron Emission Tomography, and Magnetic Resonance Imaging. In Miller’s Anesthesia (pp2659-2660). Philadelphia, PA: Elsevier.

Y Arlachov and R H Ganatra. Sedation/anaesthesia in paediatric radiology. The British Journal of Radiology 2012 85:1019, e1018-e1031

In December 2016, the Department of Veterans Affairs (VA) announced that they will be maintaining the current physician-led model of care and reversing the proposal to replace physician anesthesiologists with nurse anesthetists (1). The proposal, originally published in the Federal Registrar in May 2016, had originally sought to expand the scope of certified nurse anesthetists’ role and allow them to practice without a physician supervisor.

This new rule was originally proposed to remedy the current shortage of physicians in the Department of Veterans Affairs. There was concern over whether there would be enough physician anesthesiologists to accommodate the growing number of veterans requiring anesthesia services. Many believe that Certified Registered Nurse Anesthetists provide a cost-effective and more accessible solution to the shortage of physician anesthesiologists without compromising quality of care. Since 2001, 17 states have opted to allow CRNAs to act as primary providers of anesthesia. While many CRNAs and Nurse Anesthetist medical organizations will point to studies that show that there is no difference in health outcomes of patients undergoing care from a nurse anesthetist or a physician anesthesiologist, whether these studies are reasonably conducted is still heavily debated.

Under a nurse anesthetist-led model of care, nurse anesthetists would be able to administer anesthesia and prescribe medications, which is now limited to physician anesthesiologists. The proposal drew criticism from organizations like the American Society of Anesthesiologists (ASA), which argued that completely replacing physician anesthesiologists with nurse anesthetists would compromise patient safety. The president of the ASA, Dr. Jeffrey Plagendhooperating room is a unique care setting, and anesthesia delivery is inherently dangerous and requires physician leadership to ensure patients are as safe as possible. The proposal would have allowed nurse anesthetists to replace physician anesthesiologists in the operating room. One of the main arguments against allowing full practice authority for CRNAs was that it would eliminate the current team-based approach to anesthesia care. The team-based policy is seen as an essential part of addressing Veterans’ needs in the operating room.

The agency, however, still left room in the rule for nurse anesthetists to possibly be permitted full practice authority in the future if needed (2). The VA agency stated, “Certified Registered Nurse Anesthetists (CRNA) will not be included in VA’s full practice authority under this final rule, but comment is requested on whether there are access issues or other unconsidered circumstances that might warrant their inclusion in a future rulemaking” (2). The Department of Veterans Affairs is not opposed to giving nurses full practice authority, as evidence by its inclusion of certified nurse-midwives, nurse practitioners, and clinical nurse specialists in the new rule that allows for authority in the full extent of their professional competence without physician supervision. This decision has drawn opposition from the American Medical Association (AMA). The AMA’s leadership agrees with ASA and believes that shifting to a nurse-led care model will lead to compromise in patient safety. Both groups actively lobbied against this new proposal.

In addition to medical professional organizations, the rule also attracted a lot of attention from the public. The VA saw more than 104,000 comments in support of maintaining the physician-led model that kept the team-based approach. 11,000 of the 104,000 comments were submitted by Veterans, and 14,000 were by family members of Veterans (3). With the outpour of opposition from physicians, Veterans, family members, and the general public to permitting Nurse Anesthetists full practice authority, it is clear why the Department of Veterans Affairs has decided to keep the physician-led model. Since the new revision has been published, the public has 30 days to weigh in on the decision on the government regulation’s website.

Sources:

1. http://www.newswise.com/articles/physician-anesthesiologists-applaud-va-decision-to-reverse-proposal-to-replace-physician-anesthesiologists-with-nurses-for-anesthesia
2. http://www.medpagetoday.com/publichealthpolicy/militarymedicine/62054
3. http://www.newswise.com/articles/physician-anesthesiologists-applaud-va-decision-to-reverse-proposal-to-replace-physician-anesthesiologists-with-nurses-for-anesthesia

Nurses have provided anesthesia care in the United States for over a century. As professionals vital to anesthesia administration, Certified Registered Nurse Anesthetists (CRNAs) provide anesthesia to patients in every practice setting and play a role in every type of surgery or procedure. CRNAs provide a cost-effective solution to decreasing healthcare costs without compromising quality.

In a study of 500,000 individual cases conducted by RTI International, it was shown that CRNAs do not compromise the quality of healthcare services and there are no differences in patient outcomes. The requirements of becoming a CRNA are stringent. One needs a bachelor’s degree, Registered Nurse licensure in the United States, a minimum of one year of critical care experience, a master’s degree from a nurse anesthesia educational program, and to have passed the National Certification Examination. Additionally, CRNAs require recertification with 100 continuing education credits per 4-year cycle.

For areas that have few anesthesiologists, such as rural America, the primary providers of anesthesia are CRNAs. CRNAs, who have the knowledge and capacity to administer anesthesia safely, have enabled healthcare facilities in medically underserved areas to offer a wide range of treatments for their patients. Since 2001, 17 states have opted out in the Centers for Medicare & Medicaid Services’ supervision rule, allowing Nurse Anesthetists to act as the sole providers of anesthesia. Whether it is obstetrical, surgical, or ambulatory anesthesia management services, CRNAs have been the main providers of anesthesia for much of the country along with being the main providers of anesthesia for the men and women serving in the United States Armed Forces. In settings where physician supervision is required, CRNAs work as healthcare providers that constantly monitor patients while anesthesiologists supervise two to four CRNAs and patients.

The Affordable Care Act, which is estimated to have provided an additional 20 million people with healthcare coverage in the United States, covers CRNA services within their scope of practice. The vast majority of managed care plans also recognize that CRNAs provide high-quality healthcare with reduced expenses for patients and insurance companies. Many see the cost-efficiency of CRNAs as a way to help control rising healthcare costs. As healthcare insurance coverage becomes more widespread, healthcare providers in the United States will need to prepare to handle the influx of new patients. With the estimated increase of 30 million new patients in the future, CRNAs can offer a solution to offering quality service in a cost-effective way.

The evolution of modern monitoring during general anesthesia has come a long way from the days of assessing a patient’s color as a surrogate for adequate oxygenation. Pulse oximetry is now among the standard monitors mandated by the American Society of Anesthesiologists, but for all its usefulness as a non-invasive monitor, it has certain shortcomings: a dependence on pulsatility of blood flow which becomes compromised in settings of poor perfusion, motion and light artifacts, and sampling from digits and earlobes far removed from high-stakes real estate such as the brain and other essential organs. For procedures and patient populations where perfusion and oxygenation of these organs call for more reliable and accurate monitoring, often venous and arterial sampling of oxygen content is the standard of care. However, these surrogates of global oxygenation do not differentiate ischemia on a regional level. Regional oxygen balance can differ among organs and even within the same organ, making it possible for the brain to become ischemic even though systemic oxygenation is measuring within an acceptable range.

To bridge this gap in monitoring, cerebral oximetry was developed in the form of near infrared spectroscopy (NIRS). Employing light in the range of 700 to 1100 nm, NIRS can penetrate tissue to a depth of several centimeters. Like pulse oximetry, its algorithm employs the Beer Lambert law of light absorption. However, instead of measuring predominantly arterial hemoglobin saturation which is dependent on pulsatile flow and perfusion, NIRS samples a volume of tissue which includes arteries, capillaries and veins, with predominant venous weighting. Thus when the pulse oximetry signal flatlines during cardiopulmonary bypass, a NIRS monitor applied to the forehead is able to continue monitoring oxygen saturation in the frontal cortex, potentially alerting the anesthesiologist to sentinel desaturations calling for intervention.

Cerebral oximetry has been validated against previously existing forms of cerebral perfusion monitoring. NIRS has been shown to correlate well with changes in transcranial Doppler measurements, EEG waveforms, and stump pressure. Several manufacturers offer NIRS systems, each with its own specific algorithm. No one system is considered the gold standard, thus each is its own control, with clinical significance evaluated relative to patient baselines taken at the beginning of the procedure. Each manufacture-specific device has its own set of normal values, ranging from 55% to 80%. A reduction of frontal cortical oxygenation by 20% to 25%, or an absolute value below 50%, is the recommended threshold for intervention. Desaturations lower than these thresholds have been shown in retrospective studies to be associated with increased ICU and hospital stays, worsened morbidity and mortality, and postoperative cognitive impairment.

The usefulness of cerebral oximetry in influencing intraoperative decision-making has been studied in cardiac, abdominal, thoracic, vascular and orthopedic surgery. Interventions in response to desaturations in cerebral oximetry are aimed at improving brain oxygen delivery or decreasing oxygen demand. Fluid bolus, vasoconstrictors, increasing delivered FIO2, blood transfusion and propofol bolus are among measures studied to have a positive impact on postoperative outcomes. Surgery-specific interventions such as carotid shunt placement, application of CPAP during one lung ventilation, and repositioning during beach chair position may be better informed by the use of cerebral oximetry, however evidence as to when exactly these interventions should be applied based on NIRS data alone is still limited. Cerebral oximetry should be taken as another piece in the anesthetic armament of patient monitoring, offering more specific data on regional brain oxygen delivery and aiding more informed intraoperative decision making. Its role in the provision of anesthetic services will surely continue to evolve as further research is conducted.

References:

Casati A, Fanelli G, Pietropaoli P, et al. Continuous monitoring of cerebral oxygen saturation in elderly patients undergoing major abdominal surgery minimizes brain exposure to potential hypoxia. Anesth Analg 2005;101:740–7.

Miller, Ronald D. (2015) Tissue Oxygenation. In Miller’s Anesthesia (pp 1549-1551). Philadelphia, PA: Elsevier.

Vretzakis, George et al. “Cerebral Oximetry in Cardiac Anesthesia.” Journal of Thoracic Disease 6.Suppl 1 (2014): S60–S69. PMC. Web. 12 Dec. 2016.

A growing number of patients are undergoing same-day surgery and receiving anesthesia services as an outpatient, obviating the need to stay overnight in the hospital and allowing for a more comfortable recovery at home.  Patients tend to be more satisfied with their operation when done at an ambulatory surgery center (ASC), and having these procedures done in an outpatient setting can dramatically lower medical costs without any significant difference in complication rates [1].  ASCs have transformed the outpatient experience for millions of Americans by providing high quality care while resulting in positive patient outcomes.

Many ear, nose, and throat (ENT) procedures are performed safely in free standing ASCs, including laryngoscopy, tonsillectomy and adenoidectomy, endoscopic sinus surgery, rhinoplasty, tympanostomy, tympanoplasty, and mass excision or biopsy.  These cases are usually done under general anesthesia which involves complete loss of consciousness, sensation of pain, and ability to protect one’s airway.  Depending on the location and type of surgery, some can be performed under monitored anesthesia care or sedation.  Many of these procedures are completed in less than 1-2 hours, making them suitable for an ambulatory setting.

Special anesthetic considerations for ENT cases include sharing a potentially difficult airway with the surgeon, which necessitates excellent communication critical to minimizing complications.  It is important for the surgery and anesthesia teams to have a mutual understanding of the plan for airway management, muscle relaxation, patient positioning, post-operative pain and nausea/vomiting management, and patient-specific concerns.  Special endotracheal tubes with smaller sizes may be necessary, and awake fiberoptic intubation may be indicated for an anticipated difficult airway.  Nasal intubation may be preferred or necessary versus oral intubation for surgical access reasons.  Securement of the tube is essential given that the patient is usually positioned 90-180 degrees away from the anesthesiologist, preventing immediate access to the airway should movement of the tube or extubation occur.  Discussion of an airway management back up plan is necessary for every case, should an emergency arise, especially in the setting of a free standing ASC where resources may be relatively limited.

Anesthesia services at an ASC are comprehensive and include an anesthesiologist performing the preoperative evaluation, intraoperative management, and immediate postoperative care with discharge planning.  Most patients are discharged home within a few hours with the help of a reliable adult who can drive them home.  Occasionally, patients may need to stay overnight for observation due to persistent nausea/vomiting, uncontrolled pain, excessive bleeding, unstable level of consciousness, or for close monitoring after any other perioperative complication or adverse events.  Per the guidelines of the American Society of Anesthesiologists, a physician anesthesiologist must supervise all phases of anesthesia care at an ASC, and personnel trained in advanced resuscitative techniques should stay until every patient is discharged. In rare cases, a patient may need to be transferred to a nearby hospital for management of serious complications [2].

Not all ENT surgeries can be performed as an outpatient, and the appropriate surgical setting must be carefully considered on a case by case basis during the preoperative evaluation.  The American Academy of Otolaryngology-Head and Neck Surgery (AAO-HNS) supports general standards for surgical procedures that may be appropriately performed in an ASC setting, and general exclusions include procedures that involve expected extensive blood loss, major or prolonged invasion of body cavities, direct involvement of major blood vessels, or are emergent or life threatening in nature [3].

That said, a large variety of ENT cases can be successfully done in an outpatient setting.  For the anesthesia providers and surgeons, the ASC setting offers efficient quality care, convenience, and patient satisfaction, allowing physicians to focus on a small number of processes in a single setting while maximizing patient-doctor interaction.  ASCs provide a responsive environment tailored to individual patient needs as well as more precise control over scheduling with fewer delays and rescheduled procedures [4], reducing unnecessary health care costs. Overall, ASCs represent a positive trend in health care, with increasing outcomes in patient satisfaction and safety track records.

References

1. Monnard C, et al. Outpatient ENT surgery in an academic center: one and a half year’s experience. Acta Otorhinolaryngol Belg. 1999; 53 (2): 99-103.
2. American Society of Anesthesiologists. Office Based Anesthesia and Surgery. http://www.asahq.org/lifeline/types%20of%20anesthesia/office%20based%20anesthesia%20and%20surgery
3. American Academy of Otolaryngology-Head and Neck Surgery. Position statement: Ambulatory procedures. Revised 3/20/2016. http://www.entnet.org/content/ambulatory-procedures
4. Ambulatory Surgery Center Association. 2012. Ambulatory surgery centers: a positive trend in health care. http://www.ascassociation.org/communities/community-home/librarydocuments/viewdocument?DocumentKey=7d8441a1-82dd-47b9-b626-8563dc31930c