The beach chair position for shoulder surgery in intravenous general anesthesia and controlled hypotension: Impact on cerebral oxygenation, cerebral blood flow and neurobehavioral outcome.

STUDY OBJECTIVES: The aim of this study was to assess the impact of intravenous general anesthesia and controlled hypotension on cerebral saturation (rScO2), cerebral blood flow measured as middle cerebral artery blood flow velocity (Vmax MCA) and neurobehavioral outcome in patients scheduled for shoulder surgery in beach chair position. DESIGN: Prospective, assessor-blinded observational study. SETTING: University hospital, shoulder surgery operating room. PATIENTS: Forty ASA I-II patients scheduled for shoulder surgery in beach chair position and controlled hypotension. INTERVENTIONS: Neurological and neurobehavioral tests were performed prior and the day after surgery. The baseline data for near-infrared spectroscopy, bispectral index, cerebral blood flow, PaCO2 and invasive blood pressure (radial artery) were taken prior anesthesia and after anesthesia induction, after beach chair positioning and all 20 min after surgery start until discharge of the patient. MEASUREMENTS: Neurological and neurobehavioral tests, cerebral saturation (rScO2) using near-infrared spectroscopy, BIS, cerebral blood flow using Doppler of the middle cerebral artery (Vmax MCA), PaCO2 and invasive blood pressure assessed at heart and at the external acoustic meatus level. MAIN RESULTS: The incidence of cerebral desaturation events (CDEs) was 25%. The blood pressure drop 5 min after beach chair position measured at the acoustic meatus level in the CDE group was higher compared to patients without CDEs (p = 0.009) as was the rScO2 (p = 0.039) and the Vmax MCA (p = 0.002). There were no neurological deficits but patients with CDEs showed a greater negative impact on neurobehavioral tests 24 h after surgery compared to patients without CDEs (p = 0.001). CONCLUSIONS: In ASA I-II patients intravenous general anesthesia and controlled hypotension in the beach chair position affects cerebral blood flow and cerebral oxygenation with impact on the neurobehavioral outcome.

Blind Intubation through Self-pressurized, Disposable Supraglottic Airway Laryngeal Intubation Masks: An International, Multicenter, Prospective Cohort Study.

BACKGROUND: Supraglottic airway devices commonly are used for securing the airway during general anesthesia. Occasionally, intubation with an endotracheal tube through a supraglottic airway is indicated. Reported success rates for blind intubation range from 15 to 97%. The authors thus investigated as their primary outcome the fraction of patients who could be intubated blindly with an Air-Qsp supraglottic airway device (Mercury Medical, USA). Second, the authors investigated the influence of muscle relaxation on air leakage pressure, predictors for failed blind intubation, and associated complications of using the supraglottic airway device. METHODS: The authors enrolled 1,000 adults having elective surgery with endotracheal intubation. After routine induction of general anesthesia, a supraglottic airway device was inserted and patients were ventilated intermittently. Air leak pressure was measured before and after full muscle relaxation. Up to two blind intubation attempts were performed. RESULTS: The supraglottic airway provided adequate ventilation and oxygenation in 99% of cases. Blind intubation succeeded in 78% of all patients (95% CI, 75 to 81%). However, the success rate was inconsistent among the three centers (P < 0.001): 80% (95% CI, 75 to 85%) at the Institute of Anesthesia and Pain Therapy, Kantonsspital Winterthur, Winterthur, Switzerland; 41% (95% CI, 29 to 53%) at the Department of Anesthesiology and Intensive Therapy, Medical University of Lodz, Lodz, Poland; and 84% (95% CI, 80 to 88%) at the Institute of Anesthesiology, University Hospital Zurich, Zurich, Switzerland. Leak pressure before relaxation correlated reasonably well with air leak pressure after relaxation. CONCLUSIONS: The supraglottic airway device reliably provided a good airway and allowed blind intubation in nearly 80% of patients. It is thus a reasonable initial approach to airway control. Muscle relaxation can be used safely when unparalyzed leak pressure is adequate.

Transcutaneous continuous carbon dioxide tension monitoring reduced incidence, degree and duration of hypercapnia during combined regional anaesthesia and monitored anaesthesia care in shoulder surgery patients.

We studied the impact of transcutaneous continuous carbon dioxide tension (PtcCO2) monitoring on ventilation and oxygenation during monitored anaesthesia care (MAC) in patients scheduled for shoulder surgery with continuous interscalene block. 50 patients were randomised either to the intervention (I-group) or the control (C-group) group. In both groups MAC was performed using target controlled infusion of propofol and remifentanil. MAC regimen was adapted to PtcCO2 values in the I-group, whereas the C-group was blinded for these values. Primary outcome was the incidence, degree and duration of hypoventilation stages. In the I-group and the C-group the mean ± SD [range] of PtcCO2 and PaCO2 was 5.79 ± 0.84 [4.37] and 5.44 ± 0.59 [2.78] kPa, as well as 6.41 ± 1.17 [6.29] and 6.01 ± 0.96 [7.15] kPa. Periods of PtcCO2/PaCO2 > 6.5 kPa were 21.0 ± 35.7/1.2 ± 4.2 min in the I-group and 45.6 ± 40.0/18.6 ± 26.8 min in the C-group. Severe hypercapnia (PtcCO2 and/or PaCO2 > 7.5 kPa) was dected in 3/0 patients of the I-group and in 10/3 patients of the C-group. PtcCO2 and PaCO2 showed a strong correlation (r = 0.78), but only moderate agreement with a mean bias (LOA) of -0.37 (-1.69; +0.95) kPa showing an overestimation of the PaCO2. Sensitivity and specificity of PtcCO2 to detect changes of PaCO2 was 0.94 and 0.56, respectively. In no patient SpO2 or SaO2 values lower than 90% were measured. Despite a moderate agreement between PaCO2 and PtcCO2 the PtcCO2 monitoring significantly reduced incidence, degree and duration of hypercapnia in shoulder surgery patients with MAC.