The Use of Somatosensory Evoked Potentials to Determine the Relationship Between Intraoperative Arterial Blood Pressure and Intraoperative Upper Extremity Position-Related Neurapraxia in the Prone Surrender Position During Spine Surgery: A Retrospective Analysis.

BACKGROUND: Peripheral nerve injury is a significant perioperative problem. Intraoperative position-related neurapraxia may indicate impending peripheral nerve injury and can be detected by changes in somatosensory evoked potentials (SSEP). The purpose of this retrospective analysis of spine surgeries performed under general anesthesia with SSEP monitoring was to determine the relationship between intraoperative mean arterial blood pressure (MAP) and intraoperative upper extremity position-related neurapraxia in the prone surrender (superman) position. METHODS: We reviewed a computerized database of spine surgeries performed on adult patients in the prone surrender position. The authors reviewed intraoperative SSEP monitoring reports to identify the patients who developed intraoperative upper extremity position-related neurapraxia (case group) and patients who did not (control group). Propensity matching was performed to derive 2 demographically matched groups. Preoperative and intraoperative variables were included in the univariate Cox regression analysis of risk factors associated with neurapraxia. Multivariate Cox regression models were used to identify the independent risk factors. RESULTS: One hundred fifty-two patients were included in the analysis. The case group included 32 patients, whereas the control group included 120 matched patients. Intraoperative MAP <55 mm Hg for a total duration of ≥5 minutes was an independent risk factor associated with a greater incidence of upper extremity position-related neurapraxia compared with a duration of <5 minutes with MAP <55 mm Hg (hazard ratio, 3.43; confidence interval, 1.445-8.148; P = 0.0052). Intraoperative MAP >80 mm Hg for a total duration of >55 minutes was an independent predictor associated with a lower incidence of neurapraxia compared with a total duration ≤55 minutes (hazard ratio, 0.341; confidence interval, 0.163-0.717; P = 0.0045). CONCLUSIONS: In this study, we identified the changes in intraoperative MAP as independent predictors associated with upper extremity position-related neurapraxia in the prone surrender position under general anesthesia.

One-Year Experience with the Institution of a Critical Airway Team at an Academic Medical Center.

BACKGROUND: At our institution, there were a number of adverse patient events related to an unstable airway that led to the formation of a designated critical airway response team (CAT). It was hoped that this would improve patient outcomes in such matters. OBJECTIVE: Our aim was to evaluate the impact of the creation of the CAT. METHODS: A review of the activations of the CAT for 1 year was conducted. RESULTS: We reviewed 51 CAT activations, the majority (71%) occurred in the emergency department (ED) and the most common reasons for activation were angioedema (41%) and epiglottitis (12%). Fiber optic intubation was the most common method used to secure the airway, 22% of the cases were transported to the operating room for management. Only one surgical airway was required and no adverse outcome related to the airway occurred in the studied group. CONCLUSIONS: The creation of a critical airway has been considered a success in terms of patient management at our institution. It has been most commonly used in the management of life-threatening angioedema in the ED.

Intralipid therapy for inadvertent peripheral nervous system blockade resulting from local anesthetic overdose.

Although local anesthetics have an acceptable safety profile, significant morbidity and mortality have been associated with their use. Inadvertent intravascular injection of local anesthetics and/or the use of excessive doses have been the most frequent causes of local anesthetic systemic toxicity (LAST). Furthermore, excessive doses of local anesthetics injected locally into the tissues may lead to inadvertent peripheral nerve infiltration and blockade. Successful treatment of LAST with intralipid has been reported. We describe a case of local anesthetic overdose that resulted in LAST and in unintentional blockade of peripheral nerves of the lower extremity; both effects completely resolved with administration of intralipid.

The use of the Molt mouth gag to assist in oral fiberoptic tracheal intubation of a developmentally challenged patient presenting with severe trismus.

Airway management in developmentally challenged, and often uncooperative, patients presents difficulty for the anesthesiologist and may be further complicated by severe trismus. We describe a case wherein the use of the Molt mouth gag significantly facilitated airway control using fiberoptic tracheal intubation.

Positioning patients for spine surgery: Avoiding uncommon position-related complications.

Positioning patients for spine surgery is pivotal for optimal operating conditions and operative-site exposure. During spine surgery, patients are placed in positions that are not physiologic and may lead to complications. Perioperative peripheral nerve injury (PPNI) and postoperative visual loss (POVL) are rare complications related to patient positioning during spine surgery that result in significant patient disability and functional loss. PPNI is usually due to stretch or compression of the peripheral nerve. PPNI may present as a brachial plexus injury or as an isolated injury of single nerve, most commonly the ulnar nerve. Understanding the etiology, mechanism and pattern of injury with each type of nerve injury is important for the prevention of PPNI. Intraoperative neuromonitoring has been used to detect peripheral nerve conduction abnormalities indicating peripheral nerve stress under general anesthesia and to guide modification of the upper extremity position to prevent PPNI. POVL usually results in permanent visual loss. Most cases are associated with prolonged spine procedures in the prone position under general anesthesia. The most common causes of POVL after spine surgery are ischemic optic neuropathy and central retinal artery occlusion. Posterior ischemic optic neuropathy is the most common cause of POVL after spine surgery. It is important for spine surgeons to be aware of POVL and to participate in safe, collaborative perioperative care of spine patients. Proper education of perioperative staff, combined with clear communication and collaboration while positioning patients in the operating room is the best and safest approach. The prevention of uncommon complications of spine surgery depends primarily on identifying high-risk patients, proper positioning and optimal intraoperative management of physiological parameters. Modification of risk factors extrinsic to the patient may help reduce the incidence of PPNI and POVL.

Anesthetic considerations in candidates for lung volume reduction surgery.

The administration of anesthesia to patients undergoing lung volume reduction surgery (LVRS) requires a complete understanding of the pathophysiology of severe chronic obstructive pulmonary disease, the planned surgical procedure, and the anticipated postoperative course for this group of patients. Risk factors and associated morbidity and mortality are discussed within the context of patients with obstructive pulmonary disease in the National Emphysema Treatment Trial having surgical procedures. Preoperative evaluation and the anesthetic techniques used for patients undergoing LVRS are reviewed, as are monitoring requirements. Intraoperative events, including induction of anesthesia, lung isolation, management of fluid requirements, and options for ventilatory support are discussed. Possible intraanesthetic complications are also reviewed, as is the optimal management of such problems, should they occur. To minimize the potential for a surgical air leak in the postoperative period, positive-pressure ventilation must cease at the conclusion of the procedure. An awake, comfortable, extubated patient, capable of spontaneous ventilation, is only possible if there is careful attention to pain control. The thoracic epidural is the most common pain control method used with patients undergoing LVRS procedures; however, other alternative methods are reviewed and discussed.

The use of somatosensory evoked potentials to determine the relationship between patient positioning and impending upper extremity nerve injury during spine surgery: a retrospective analysis.

Somatosensory evoked potential (SSEP) monitoring is used to prevent nerve damage in spine surgery and to detect changes in upper extremity nerve function. Upper extremity SSEP conduction changes may indicate impending nerve injury. We investigated the effect of operative positioning on upper extremity nerve function retrospectively in 1000 consecutive spine surgeries that used SSEP monitoring. The vast majority (92%) of upper extremity SSEP changes were reversed by modifying the arm position and were therefore classified as position-related. The incidence of position-related upper extremity SSEP changes was calculated and compared for five different surgical positions: supine arms out, supine arms tucked, lateral decubitus position, prone arms tucked, and the prone "superman" position. The overall incidence of position-related upper extremity SSEP changes was 6.1%. The lateral decubitus position (7.5%) and prone superman position (7.0%) had a significantly more frequent incidence of position-related upper extremity SSEP changes (P < 0.0001, Z-test for Poisson counts) compared with other positions (1.8%-3.2%). No patient with a reversible SSEP change developed a new postoperative deficit in the affected extremity. SSEP monitoring is of value in identifying and reversing impending upper extremity peripheral nerve injury.