Perioperative and Anesthesia Management




1


Introduction


Obstructive sleep apnea/hypopnea syndrome (OSAHS) is a growing health care concern with many potentially detrimental consequences and important anesthetic implications. A rise in obesity among the population of the United States corresponds with an upswing in the prevalence of OSAHS. Over the last two decades, the prevalence of OSAHS increased from 26.4% to 33.9% in males and from 13.2% to 17.4% in females. An elevation in the body mass index (BMI) of one standard deviation increases the likelihood of coexisting OSAHS by a factor of four. In the morbidly obese population, the incidence of obstructive sleep apnea (OSA) is approximately 55% in women and 77% in men. Undiagnosed and/or untreated OSA leads to an increased risk of adverse perioperative events, specifically serious pulmonary complications: difficult mask ventilation, difficult direct laryngoscopy or fiber-optic intubations, desaturation and/or airway obstruction, aspiration pneumonia, acute respiratory distress syndrome, or even death.


The airway obstruction in OSAHS patients results from a decrease in the upper airway muscle tone during sleep; airway narrowing due to the deposition of adipose tissue; and resultant increase in size of pharyngeal structures: the uvula, tonsils, tonsillar pillars, tongue, aryepiglottic folds, and the lateral pharyngeal walls ( Fig. 14.1 ). As a result, the shape of the pharynx changes from a long transverse (lateral) and a short anterior–posterior axis into a narrower ellipsoid with a shorter transverse and a longer anterior–posterior axis. This change in shape impairs the action of the anterior pharyngeal airway dilators: the tensor veli palitini, genioglossus, and hyoid muscles ( Fig. 14.2 ).






FIG. 14.1


(A) The action of the most important dilator muscles of the upper airway. The tensor palatine, genioglossus, and hyoid muscles enlarge the nasopharynx, oropharynx, and the laryngopharynx, respectively. (B) Collapse of the nasopharynx at the palatal level, the oropharynx at the glottic level, and the laryngopharynx at the epiglottic level.

(Modified from Benumof JL: Obstructive sleep apnea in the adult obese patient: implications for airway management. J Clin Anesth 2001;13[2]:144–56, with permission.)



FIG. 14.2


The effects of a 5-mm change in the anteroposterior (AP) diameter of the airway on airway cross-sectional area is shown for two equally elliptical airways with different lateral/AP ratios. (A) The lateral/AP ratio = 0.5. (B) The lateral/AP ratio = 2. The lateral dimension of each ellipse was held constant. The solid line represents the starting area (3 cm 2 in both ellipses), and the dotted line represents the area after a 5-mm increase in the AP diameter. The area change is greater in the ellipse with a more lateral orientation (B).

(From Leiter JC: Upper airway shape. Is it important in the pathogenesis of obstructive sleep apnea? Am J Respir Crit Care Med 1996;153:894–8, with permission.)


A substantial number of patients seen in the operative units may have undiagnosed and untreated OSAHS. Recent reports have shown that approximately one-quarter of patients undergoing elective surgery have OSAHS, and over 80% of these cases are undiagnosed. High prevalence of undiagnosed OSAHS necessitates utmost vigilance, as well as prevention and early recognition of potentially devastating complications. The inability to intubate the patient, respiratory obstruction after tracheal extubation, and severe respiratory depression and respiratory arrest after the administration of sedatives and narcotics are some of the biggest concerns for anesthesiologists. Gupta et al. compared the occurrence of perioperative complications in OSA ( n = 101) and non-OSA patients ( n = 101) after a hip or knee replacement and reported 39% and 18% complication rates (hypoxemia, hypercapnia, delirium) in the two groups, respectively. These results are corroborated by a number of other large studies, which demonstrate an increased likelihood of perioperative respiratory complications in patients undergoing various types of surgical procedures.


Practice guidelines for the perioperative management of patients with OSAHS published by the American Society of Anesthesiologists (ASA) recommend the use of a scoring system to estimate a risk for perioperative complications from OSAHS, which incorporates three factors: (1) the severity of OSAHS, (2) the invasiveness of the surgery and anesthesia, and (3) the requirement for postoperative opioids ( Table 14.1 ). Patients with an overall score of 5 or greater have an increased risk of perioperative complications.



Table 14.1

Summary of the Recommendations for the Perioperative Care of OSA Patients Developed by the American Society of Anesthesiologists




















  • I.

    Preoperative evaluation




  • Collaboration between anesthesiologists and surgeons is advised to develop a perioperative plan for patients with suspected sleep apnea



  • Preoperative evaluation should include a review of past medical records, interview with the patient and/or family, and physical examination



  • Sleep studies should also be reviewed if available



  • II.

    Inpatient/outpatient surgery

Determination should be made after careful assessment of (1) presence of OSA, (2) anatomic and physiologic derangements, (3) comorbidities, (4) nature of surgery, (5) type of anesthesia, (6) need for postoperative opioids, (7) patient’s age, (8) adequacy of postoperative monitoring, and (9) capabilities of the outpatient center


  • III.

    Preoperative preparation




  • Careful selection of the intraoperative medications to minimize the risk of respiratory compromise



  • Use local anesthetics or peripheral nerve blocks with or without moderate sedation for superficial procedures



  • Continuous monitoring by capnography of the ventilator status in the presence of moderate sedation due to increased risk of airway obstruction



  • Administer CPAP or oral appliance during sedation in patients previously using the devices



  • Secure airway during general anesthesia and deep sedation



  • Use neuraxial anesthesia (spinal/epidural) for peripheral procedures



  • Extubate after a full reversal of the neuromuscular blockade



  • Extubate in the lateral, semi-upright, or other nonsupine position



  • IV.

    Postoperative management




  • Consider using regional analgesia to avoid using systemic opioids



  • Evaluate risks and benefits of using neuraxial analgesia using opioid only or opioid–local anesthetic mixture versus local anesthetic only



  • Avoid or use with caution continuous background infusions of medication when using patient-controlled analgesia (PCA) with systemic opioids



  • Consider using nonopioid analgesics to reduce the requirement for narcotic medications



  • Exercise caution when combining benzodiazepines and barbiturates, as they increase the risk of respiratory depression



  • Judicious use of supplemental oxygen, as it may also suppress respiratory drive



  • Use CPAP or noninvasive positive pressure ventilation in patients who were using them preoperatively



  • Keep patients in the nonsupine position throughout the recovery process



  • Use continuous pulse oximetry after transfer from the recovery unit into stepdown or telemetry



  • In the event of hypoxemia, frequent, or severe airway obstruction, apply nasal CPAP or noninvasive positive pressure ventilation



  • V.

    Criteria for discharge to unmonitored settings




  • Postpone discharge until patients are no longer at risk of respiratory compromise



  • Monitor the adequacy of oxygen saturation on room air while patient is sleeping


Adapted from


The rate of possible complications varies between different types of anesthesia provided. Memtsoudis et al. assessed perioperative outcomes in 30,024 patients diagnosed with OSAHS who underwent an orthopedic surgery between 2006 and 2010 under neuraxial and/or general anesthesia. The authors found lower rates of perioperative complications (pulmonary and cardiac and need for blood products) and improved postoperative outcomes (mechanical ventilation, intensive care unit [ICU] admission, length and cost of hospitalization) in patients under neuraxial anesthesia (16.0%) compared with general (17.2%) or combined neuraxial-general anesthesia (18.1%) and concluded that the neuraxial anesthesia may be a more beneficial option for patients with OSA. Respiratory compromise can also occur after regional anesthesia as shown by a retrospective study of 206 patients with OSA scheduled for an orthopedic surgery in an outpatient setting, where 34% of the patients experienced hypoxemia postoperatively. Despite those results, Sabers et al. demonstrate that presence of OSA does not increase the risk of adverse events or unforeseen hospital admissions in patients undergoing procedures in the outpatient center. Thus the Society for Ambulatory Anesthesia concluded that patients diagnosed with OSA can be selected for an outpatient procedure if the following criteria are met: comorbid conditions are managed, patients are able to use their continuous positive airway pressure (CPAP) device postoperatively, and the postprocedural pain can be adequately managed with nonopioid medications. After an extensive review of the available scientific literature, the ASA developed specific guidelines and recommendations for the perioperative care of patients diagnosed with OSA ( Table 14.2 ).



Table 14.2

Scoring System for Calculation of Perioperative Risk in Patients With OSAHS ‡







  • A.

    Severity of sleep apnea based on sleep study (or clinical indicators if sleep study not available). Point score ______ (0–3). * †




    • 0. None (AHI = 0–5)



    • 1. Mild (AHI = 6–20)



    • 2. Moderate (AHI = 21–40)



    • 3. Severe (AHI > 40)



  • B.

    Invasiveness of the surgery and anesthesia. Point score ______ (0–3).




    • 0. Superficial surgery under local or peripheral nerve block without sedation



    • 1. Superficial surgery with moderate sedation or general anesthesia or peripheral surgery with spinal or epidural anesthesia



    • 2. Peripheral surgery with general anesthesia or airway surgery with moderate sedation



    • 3. Major surgery or airway surgery with general anesthesia



  • C.

    Requirement of postoperative opioids. Point score ______ (0–3).




    • 0. None



    • 1. Low-dose oral opioids



    • 2. High-dose oral, parenteral, or neuroaxial opioids


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Jun 10, 2019 | Posted by in OTOLARYNGOLOGY | Comments Off on Perioperative and Anesthesia Management

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