Cerebral oximetry desaturation during shoulder surgery performed in a sitting position under regional anesthesia.

PURPOSE: Hypotension in the sitting position may reduce cerebral perfusion and oxygenation. We prospectively determined the incidence of cerebral oximetry (rSO2) desaturation in seated patients undergoing ambulatory shoulder arthroscopy. METHODS: A cohort of 99 patients received regional anesthesia and intravenous sedation, and their blood pressure was recorded every five minutes. Hypotension was defined as the occurrence of any of the following: > 30% decline in mean arterial pressure (MAP), systolic blood pressure < 90 mmHg, or MAP <66 mmHg. Cerebral desaturation was defined as a > 20% decrease in rSO2 from baseline. The association of rSO2 desaturation with potential risk factors was examined by the generalized estimating equation to account for within patient correlation and multiple observations per patient. We fitted desaturation with three models: 1) unadjusted (i.e., hypotension as sole regressor); 2) time-trend adjusted; and 3) baseline-factors adjusted model. RESULTS: Hypotension occurred in 76% of observations (mean duration 4,261 sec), but cerebral desaturation was seen in only 0.77% of observations (mean duration 426 sec). Ninety-nine percent of patients experienced hypotension, but cerebral desaturation occurred in only 10%. By unadjusted modelling, hypotension was associated with cerebral desaturation (odds ratio = 3.21; P = 0.02). Once time-trend adjusted, cerebral desaturation was associated with time from baseline but not with hypotension (P = 0.14). When adjusted for baseline factors, the analysis demonstrated a non-significant association with hypotension (P = 0.34) but a significant association with the presence of risk factors for cerebrovascular disease (P = 0.01). CONCLUSIONS: Despite frequent hypotension in the sitting position, rSO2 desaturation was uncommon during shoulder arthroscopy performed in the sitting position with regional anesthesia.

Stroke, regional anesthesia in the sitting position, and hypotension: a review of 4169 ambulatory surgery patients.

BACKGROUND AND OBJECTIVE: Intraoperative hypotension is used to reduce surgical bleeding. Case reports of stroke after general anesthesia in the sitting position led us to collect data (patient demographics, medical risk factors for stroke, intraoperative hemodynamics) about the incidence of stroke after surgery in the sitting position. METHODS: This study reviewed 4169 (3000 retrospective, 1169 prospective) ambulatory shoulder surgeries in the sitting position. For the prospective cohort, patients were queried postoperatively regarding stroke, with corroboration from 4 databases (anesthesia department quality assurance, hospital case management, state-reportable events, and hospital information system diagnostic code databases). For the retrospective cohort, rate of stroke was determined via the same 4 databases. RESULTS: No patient had a stroke (95% confidence interval, 0%-0.07%). Risk factors for perioperative stroke were present in 40% of patients. Brachial plexus nerve block with intravenous sedation was used for 95.7% (retrospective) and 99.8% (prospective) of the cohorts. Many patients (47%) experienced intraoperative hypotension by at least one definition: 40% (retrospective) and 30% (prospective) had at least a 30% decrease in mean arterial pressure; 27% (retrospective) and 24% (prospective) had a mean pressure less than 66 mm Hg; and 13% (retrospective) and 12% (prospective) had a systolic blood pressure of less than 90 mm Hg. CONCLUSIONS: No strokes were observed in 4169 patients. The estimated upper limit of the 95% confidence interval for stroke after regional anesthesia for shoulder surgery in the seated position is 0.07%, despite frequent incidence of hypotension.

Uncomplicated removal of epidural catheters in 4365 patients with international normalized ratio greater than 1.4 during initiation of warfarin therapy.

BACKGROUND AND OBJECTIVES: Current guidelines from the American Society of Regional Anesthesia state that an international normalized ratio (INR) of 1.4 is the upper limit of warfarin anticoagulation for safe removal of an epidural catheter. However, these guidelines are based primarily on expert consensus, and there is controversy regarding this recommendation as being "too conservative." METHODS: Prospective (3211) and retrospective (1154) patients undergoing total joint replacement followed by daily warfarin thromboprophylaxis were enrolled in this observational study. All nonsteroidal anti-inflammatory drugs and anticoagulants were held before surgery, and all patients had normal coagulation test results before surgery. Patients were followed twice a day by the acute pain service, no other anticoagulants except nonsteroidal anti-inflammatory drugs were administered, and epidural analgesia was discontinued per institutional protocol. Only patients with INR greater than 1.4 at the time of removal of epidural catheter were included. Neurologic checks were performed for 24 hrs after removal. RESULTS: A total of 4365 patients were included, and 79% underwent knee replacement and 18% hip replacement. Mean age was 68 yrs, and mean weight was 81 kg. Mean (SD) duration of epidural analgesia was 2.1 (0.6) days. Mean (SD) INR at the time of epidural removal was 1.9 (0.4), ranging from 1.5 to 7.1. No spinal hematomas were observed (0% incidence with 95% confidence interval, 0%-0.069%). CONCLUSIONS: Our series of 4365 patients had uncomplicated removal of epidural catheters despite INRs ranging from 1.5 to 5.9. Removal was only during initiation of warfarin therapy (up to approximately 50 hrs after warfarin intake) when several vitamin K factors are likely to still be adequate for hemostasis.

A prospective clinical registry of ultrasound-guided regional anesthesia for ambulatory shoulder surgery.

BACKGROUND: There is a lack of clinical registries to document efficacy and safety of ultrasound-guided regional anesthesia. Interscalene blocks are effective for shoulder arthroscopy, and ultrasound guidance may reduce risk. Furthermore, ultrasound-guided supraclavicular block is a novel approach for shoulder anesthesia that may have less risk for neurological symptoms than interscalene block. METHODS: One thousand one hundred sixty-nine patients undergoing ultrasound-guided regional anesthesia for ambulatory shoulder arthroscopy were enrolled in our prospective registry. Standardized perioperative data were collected including a preoperative neurological screening tool. Either interscalene or supraclavicular block was performed at the discretion of the clinical team. Standardized follow-up was performed in the postanesthesia care unit and at 1 week. Postoperative neurological symptoms (PONS) were assessed at the 1-week follow-up with the same screening tool by a blinded neurologist. RESULTS: Ultrasound-guided interscalene (n = 515) and supraclavicular (n = 654) blocks had excellent anesthetic success (99.8%; 95% confidence interval [CI], 99.4%-99.9%) with 0% (95% CI, 0%-0.3%) incidence of vascular puncture or intravascular injection. The incidence of hoarseness in the postanesthesia care unit was significantly less with supraclavicular (22% with 95% CI, 19%-26%) than interscalene block (31% with 95% CI, 27%-35%). The incidence of dyspnea was similar (7% for supraclavicular vs 10% with interscalene). No patient had a clinically apparent pneumothorax. The incidence of PONS was very low (0.4% with 95% CI, 0.1%-1%), and there was a 0% (95% CI, 0%-0.3%) incidence of permanent nerve injury. CONCLUSIONS: Ultrasound-guided interscalene and supraclavicular blocks are effective and safe for shoulder arthroscopy. Temporary and permanent PONS is uncommon.