Perioperative blood glucose management in patients undergoing tumor hepatectomy.

STUDY OBJECTIVE: To determine whether our institutional insulin management (modified Atlanta) protocol is efficient and safe in controlling blood glucose levels in the perioperative period in surgical patients undergoing tumor hepatectomy. DESIGN: Retrospective study. SETTING: Large community hospital. PATIENTS: 20 consecutive patients undergoing liver resection for hepatocellular carcinoma, liver metastasis, or other hepatobiliary tumors. INTERVENTIONS AND MEASUREMENTS: All patients continuously received intravenous glucose (5% dextrose in water, one mL/kg/hr); insulin was administered according to a strict algorithm, and dose adjustments were based on measurements of whole-blood glucose intraoperatively at one-hour intervals, and in the intensive care unit (ICU). Lower and upper blood glucose limits were set at 85 mg/dL and 110 mg/dL, respectively, in the operating room (OR). In the ICU, lower and upper limits were 90 mg/dL and 140 mg/dL, respectively. MAIN RESULTS: Intraoperatively, 51.3% of measurements were within the target range. In the ICU, 75.2% of measurements showed a blood glucose level of 90 - 140 mg/dL. Two of 78 (2.6%) and two of 363 (0.5%) measurements had a blood glucose level < 70 mg/dL in the OR and ICU, respectively. The lowest blood glucose levels were 65 mg/dL (OR) and 66 mg/dL (ICU). CONCLUSIONS: The modified Atlanta protocol is efficient and safe in controlling blood glucose levels in the perioperative period of hepatic tumor resection. Because of decreased insulin needs in the ICU, the use of a more liberal algorithm successfully reduced the risk of hypoglycemia.

Development and performance of a two-step desflurane-O(2)/N(2)O fresh gas flow sequence.

STUDY OBJECTIVE: To determine if the previously described single-step O(2)/N(2)O fresh gas flow (FGF) sequence could be combined with a simple desflurane vaporizer (F(D)) sequence to maintain the end-expired desflurane (F(A)des) at 4.5% with the anesthesia delivery unit machine (ADU Anesthesia Machine(R); General Electric, Helsinki, Finland). DESIGN: Prospective randomized clinical study. SETTING: Onze Lieve Vrouw Hospital, Aalst, Belgium, a large teaching hospital. PATIENTS: 42 ASA physical status I and II patients requiring general endotracheal anesthesia and controlled mechanical ventilation. INTERVENTIONS: In 18 patients undergoing general anesthesia with controlled mechanical ventilation, F(D) was determined to maintain F(A)des at 4.5% with O(2)/N(2)O FGF of two and 4 L per minute for three minutes and 0.3 and 0.4 L per minute thereafter. Using the same FGF sequence, we prospectively tested the F(D) schedule that approached this observed F(D) pattern with the fewest possible adjustments in another 24 patients. MAIN RESULTS: F(D) of 6.5% for 15 minutes followed by 5.5% thereafter approximated the observed F(D) course well. When it was prospectively tested, the median (25th, 75th percentiles) performance error was -1% (-5.1%, 5.2%); absolute performance error, 7.1% (3.9%, 9.5%); divergence, -6.6% per hour (23.1%, 3.1%/h); and wobble, 2.2% (1.8%, 3.2%). Because F(A)des increased above 4.9%, F(D) was decreased in 5 patients after 23 minutes (0.5% decrement once or twice); in two patients, F(D) was temporarily increased. In one patient, FGF was temporarily increased because the bellows volume became insufficient. CONCLUSIONS: One O(2)/N(2)O rotameter FGF setting change from 6 to 0.7 L per minute after three minutes and one desflurane F(D) change from 6.5% to 5.5% after 15 minutes maintained anesthetic gas concentrations within predictable and clinically acceptable limits during the first 20 minutes.

Desflurane Consumption During Automated Closed-circuit Delivery is Higher Than When a Conventional Anesthesia Machine is Used With a Simple Vaporizer-O2-N2O Fresh Gas Flow Sequence.

BACKGROUND: The Zeus® (Dräger, Lübeck, Germany), an automated closed-circuit anesthesia machine, uses high fresh gas flows (FGF) to wash-in the circuit and the lungs, and intermittently flushes the system to remove unwanted N2. We hypothesized this could increase desflurane consumption to such an extent that agent consumption might become higher than with a conventional anesthesia machine (Anesthesia Delivery Unit [ADU®], GE, Helsinki, Finland) used with a previously derived desflurane-O2-N2O administration schedule that allows early FGF reduction. METHODS: Thirty-four ASA PS I or II patients undergoing plastic, urologic, or gynecologic surgery received desflurane in O2/N2O. In the ADU group (n = 24), an initial 3 min high FGF of O2 and N2O (2 and 4 L.min-1, respectively) was used, followed by 0.3 L.min-1 O2 + 0.4 L.min-1 N2O. The desflurane vaporizer setting (FD) was 6.5% for the first 15 min, and 5.5% during the next 25 min. In the Zeus group (n = 10), the Zeus® was used in automated closed circuit anesthesia mode with a selected end-expired (FA) desflurane target of 4.6%, and O2/N2O as the carrier gases with a target inspired O2% of 30%. Desflurane FA and consumption during the first 40 min were compared using repeated measures one-way ANOVA. RESULTS: Age and weight did not differ between the groups (P > 0.05), but patients in the Zeus group were taller (P = 0.04). In the Zeus group, the desflurane FA was lower during the first 3 min (P < 0.05), identical at 4 min (P > 0.05), and slightly higher after 4 min (P < 0.05). Desflurane consumption was higher in the Zeus group at all times, a difference that persisted after correcting for the small difference in FA between the two groups. CONCLUSION: Agent consumption with an automated closed-circuit anesthesia machine is higher than with a conventional anesthesia machine when the latter is used with a specific vaporizer-FGF sequence. Agent consumption during automated delivery might be further reduced by optimizing the algorithm(s) that manages the initial FGF or by tolerating some N2 in the circuit to minimize the need for intermittent flushing.

Muscle relaxation does not influence venous oxygen saturation during cardiopulmonary bypass.

STUDY OBJECTIVE: To examine whether the omission of neuromuscular blocking drugs during cardiopulmonary bypass (CPB) is associated with increased anesthetic requirements, higher frequency of intraoperative movements, and lower venous oxygen saturation (SvO(2)). DESIGN: Prospective, randomized study. SETTING: Large community hospital. PATIENTS: 30 ASA physical status III and IV patients scheduled for cardiac surgery. INTERVENTIONS: Patients were randomized to one of two groups: group 1 (n = 15) received a 3xED(95) bolus dose of cisatracurium at induction and thereafter no more neuromuscular blocking drug; group 2 (n = 15) received a continuous infusion of cisatracurium during the entire procedure. INTERVENTIONS: Both groups received a standardized anesthetic with bispectral index-guided propofol target-controlled infusion and a remifentanil infusion steered by hemodynamic changes. Venous oxygen saturation was continuously determined during CPB. MEASUREMENTS AND MAIN RESULTS: Propofol consumption was 5.4 +/- 1.7 and 4.4 +/- 1.0 mg/(kg/h) in groups 1 and 2, respectively (P = 0.07). Remifentanil consumption was 0.15 +/- 0.05 and 0.17 +/- 0.05 mug/(kg/min) in groups 1 and 2, respectively (P = 0.19). In groups 1 and 2, no patient recalled any intraoperative phenomena; none moved or had diaphragmatic contractions. During CPB, SvO(2) was 81.3 +/- 3.2% (76%-85%) in group 1 and 80.6 +/- 3.1% (73%-85%) in group 2 (P = 0.53). CONCLUSIONS: Omitting the continuous administration of neuromuscular blocking drugs during CPB did not increase anesthetic requirements. No intraoperative movements occurred, nor was there decreased SvO(2).

Preinduction glycemia and body mass index are important predictors of perioperative insulin management in patients undergoing cardiac surgery.

STUDY OBJECTIVE: To investigate whether preinduction glucose is an important predictor for perioperative insulin management in patients undergoing cardiac surgery. DESIGN: Prospective cohort study. SETTING: Large community hospital. PATIENTS: 80 consecutive patients scheduled for cardiac surgery. INTERVENTIONS: Patients were subdivided into those with a preinduction blood glucose of 110 mg/dL or lower with or without history of diabetes (group 1) and those with a preinduction blood glucose of above 110 mg/dL with or without history of diabetes (group 2). In group 1, there were no known diabetics. In group 2, 31% (11/35) had diabetes (group 2DM), while 24/35 (69%) did not (group 2NDM). An insulin infusion was started intraoperatively and adjusted according to a strict protocol in order to maintain normoglycemia (80-110 mg/dL) until discharge from intensive care. MEASUREMENTS AND MAIN RESULTS: In patients with preinduction glucose above 110 mg/dL, whether or not previously treated for diabetes, perioperative insulin requirements were higher, and intraoperative insulin management was more difficult than in those with lower preinduction glucose. In patients with a preinduction glucose above 110 mg/dL, hospital stay was longer, and inhospital mortality was significantly higher than in those with lower preinduction glucose. Multivariate analyses showed that preinduction glycemia was a good predictor of intraoperative insulin consumption, as was the body mass index (BMI) for intensive care and total insulin needs. CONCLUSIONS: In cardiac surgical patients with a preinduction glucose above 110 mg/dL, even if diabetes was not previously suspected, perioperative insulin requirements were higher, and intraoperative insulin management is more difficult than in those with a preinduction glucose 110 mg/dL or lower. Preinduction glycemia and BMI are good predictors of perioperative insulin management. Preinduction glycemia above 110 mg/dL predicts difficult perioperative glucose control and, moreover, that a preinduction blood glucose of 110 mg/dL or lower is associated with less insulin need.

Intraoperative severity assessment of coronary artery stenosis in patients at risk: the role of transesophageal echocardiography.

A 71-yr-old male was scheduled for infrarenal abdominal aortic aneurysm repair. Although he had only minor clinical predictors for increased perioperative cardiovascular risk with >4 estimated metabolic equivalents for activities, intraoperative transesophageal echocardiography revealed an abnormal maximal-to-prestenotic blood flow velocity ratio in the left main coronary artery. Postoperatively, a severe distal left main coronary artery stenosis was confirmed with coronary angiography. Understanding the flow velocity patterns in the coronary arteries helps the anesthesiologist to detect coronary lesions with transesophageal echocardiography.

Postoperative residual paralysis in outpatients versus inpatients.

Postoperative residual paralysis is an important complication of the use of neuromuscular blocking drugs. In this prospective study, the incidence of residual paralysis detected as a train-of-four response <90% was less frequent in surgical outpatients (38%) than inpatients (47%) (P = 0.001). This might have been the result of the more frequent use of mivacurium for outpatients. Before undertaking tracheal extubation, the anesthesiologists had applied clinical criteria (outpatients, 49%; inpatients, 45%), pharmacological reversal (26%, 25%), neuromuscular transmission monitoring (12%, 11%), or a combination of these. None of these measures seemed to reduce the incidence of residual paralysis except for quantitative train-of-four monitoring. Postoperatively, eight individual clinical tests or a sum of these tests were also unable to predict residual paralysis by train-of-four. Although the incidence of residual paralysis was less frequent in surgical outpatients, predictive criteria were not evident.

Effect of N2O on sevoflurane vaporizer settings during minimal- and low-flow anesthesia.

BACKGROUND: Uptake of a second gas of a delivered gas mixture decreases the amount of carrier gas and potent inhaled anesthetic leaving the circle system through the pop-off valve. The authors hypothesized that the vaporizer settings required to maintain constant end-expired sevoflurane concentration (Etsevo) during minimal-flow anesthesia (MFA, fresh gas flow of 0.5 l/min) or low-flow anesthesia (LFA, fresh gas flow of 1 l/min) would be lower when sevoflurane is used in oxygen-nitrous oxide than in oxygen. METHODS: Fifty-six patients receiving general anesthesia were randomly assigned to one of four groups (n = 14 each), depending on the carrier gas and fresh gas flow used: group Ox.5 l (oxygen, MFA), group NOx.5 l (oxygen-nitrous oxide, MFA after 10 min high fresh gas flow), group Ox1 l (oxygen, LFA), and group NOx1 l (oxygen-nitrous oxide, LFA after 10 min high fresh gas flow). The vaporizer dial settings required to maintain Etsevo at 1.3% were compared between groups. RESULTS: Vaporizer settings were higher in group Ox.5 l than in groups NOx.5 l, Ox1 l, and NOx1 l; vaporizer settings were higher in group NOx.5 l than in group NOx1 l between 23 and 47 min, and vaporizer settings did not differ between groups Ox1 l and NOx1 l. CONCLUSIONS: When using oxygen-nitrous oxide as the carrier gas, less gas and vapor are wasted through the pop-off valve than when 100% oxygen is used. During MFA with an oxygen-nitrous oxide mixture, when almost all of the delivered oxygen and nitrous oxide is taken up by the patient, the vaporizer dial setting required to maintain a constant Etsevo is lower than when 100% oxygen is used. With higher fresh gas flows (LFA), this effect of nitrous oxide becomes insignificant, presumably because the proportion of excess gas leaving the pop-off valve relative to the amount taken up by the patient increases. However, other unexplored factors affecting gas kinetics in a circle system may contribute to our observations.