Current Ventilator and Oxygen Management during General Anesthesia: A Multicenter, Cross-sectional Observational Study.

BACKGROUND: Intraoperative oxygen management is poorly understood. It was hypothesized that potentially preventable hyperoxemia and substantial oxygen exposure would be common during general anesthesia. METHODS: A multicenter, cross-sectional study was conducted to describe current ventilator management, particularly oxygen management, during general anesthesia in Japan. All adult patients (16 yr old or older) who received general anesthesia over 5 consecutive days in 2015 at 43 participating hospitals were identified. Ventilator settings and vital signs were collected 1 h after the induction of general anesthesia. We determined the prevalence of potentially preventable hyperoxemia (oxygen saturation measured by pulse oximetry of more than 98%, despite fractional inspired oxygen tension of more than 0.21) and the risk factors for potentially substantial oxygen exposure (fractional inspired oxygen tension of more than 0.5, despite oxygen saturation measured by pulse oximetry of more than 92%). RESULTS: A total of 1,786 patients were found eligible, and 1,498 completed the study. Fractional inspired oxygen tension was between 0.31 and 0.6 in 1,385 patients (92%), whereas it was less than or equal to 0.3 in very few patients (1%). Most patients (83%) were exposed to potentially preventable hyperoxemia, and 32% had potentially substantial oxygen exposure. In multivariable analysis, old age, emergency surgery, and one-lung ventilation were independently associated with increased potentially substantial oxygen exposure, whereas use of volume control ventilation and high positive end-expiratory pressure levels were associated with decreased potentially substantial oxygen exposure. One-lung ventilation was particularly a strong risk factor for potentially substantial oxygen exposure (adjusted odds ratio, 13.35; 95% CI, 7.24 to 24.60). CONCLUSIONS: Potentially preventable hyperoxemia and substantial oxygen exposure are common during general anesthesia, especially during one-lung ventilation. Future research should explore the safety and feasibility of a more conservative approach for intraoperative oxygen therapy.

[Anesthetic management of awake off-pump coronary artery bypass grafting (ACAB) with remifentanil and thoracic epidural anesthesia].

Two patients with total occlusion of the right internal carotid artery, were anesthetized for ACAB with remifentanil and thoracic epidural anesthesia. Case 1: A 71-year-old man with hypertension and diabetes mellitus underwent single-vessel ACAB under IV remifentanil analgesia, the dose of which was adjusted to 0.04-0.05 microg x kg(-1) x min(-1), along with an epidural infusion of 10 ml x hr(-1) of a mixture of 2% lidocaine and 2.5 microg x ml(-1) of fentanyl, the PaCO2 being maintained at 52-55 mmHg. When the patient felt pain, the remifentanil dose was elevated to 0.08 microg x kg(-1) x min(-1) and PaCO2 increased to 60 mmHg. Case 2: A 66-year-old man with rheumatoid arthritis underwent ACAB for two grafts. An intraaortic balloon pump (IABP) was inserted preoperatively. The anesthetic method used was the same as in case 1, except for an additional right femoral block to provide anesthesia for extraction of the saphenous vein. Remifentanil was infused at 0.05 microg x kg(-1) x min(-1) and PaCO2 maintained at 49-53 mmHg. In response to the patient's pain and movement, the remifentanil dose was increased to 0.07-0.10 microg x kg(-1) x min(-1) and PaCO2 to 60 mmHg.

[Heparin resistance associated with elevated factor VIII].

An 84-year-old female patient was scheduled to undergo AVR, CABG, and Maze procedure. She had a history of hypertension, cerebral infarction, and branch retinal vein occlusion. Warfarin was administered preoperatively. Before the cardiopulmonary bypass (CPB), heparin 5,000 units was administered. Activated coagulation times (ACTs) before and after CPB were 123 sec and 157 sec, respectively. Additional heparin of 5,000 units extended ACT to 221 seconds, which was not enough for the CPB. Heparin 10,000 units was added, and ACT was 157 sec. AntithrombinIII (ATIII) and platelet counts were 75% and 270,000 mm(-3), respectively. ATIII 1,500 units was administered. ACT and ATIII became 133 sec and 123%, respectively. Because heparin resistance did not respond to ATIII, the operative method was changed to off-pump CABG. A postoperative examination revealed high factor VIII activity of 263%. Other results were as follows: protein C antigen, 40%; protein S antigen, 65%; factor VII, 50%; platelet factor 4, 12%; heparin cofactor II, 104%; von Willebrand factor antigen, 181%; heparin-PF4-IgG antibody, negative; factor VIII inhibitor, negative. The low values of protein C, protein S, and factor VII may have been caused by warfarin. Other values were normal, except for the von Willebrand factor antigen.