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Biomedical subjects

M Hynynen

Publications and source records attributed to M Hynynen.

At least 19 recordsLinked to original sources
PubMed2006

Supplemental 80% oxygen does not attenuate post-operative nausea and vomiting after breast surgery.

BACKGROUND: Although supplemental oxygen has been shown to be as effective as ondansetron in the prevention of post-operative nausea and vomiting (PONV) in one study in abdominal surgery patients, the antiemetic efficacy of supplemental oxygen is controversial on the basis of studies with other patients. We compared the efficacy of 80% and 30% oxygen in decreasing PONV in breast surgery. Ondansetron was used as an active control. METHODS: Ninety patients were given a standardized sevoflurane anesthetic. They were randomly assigned to three groups: 30% oxygen in nitrogen and saline 2 ml intravenously (i.v.) at the end of surgery (group 30); 80% oxygen in nitrogen and saline 2 ml (group 80); and 30% oxygen in nitrogen and ondansetron 4 mg (group O). Oxygen was administered during surgery and up to 2 h after surgery. RESULTS: The incidence of total response (no retching or vomiting, no nausea) during the first 24 post-operative hours was not different between group 80 (17%) and group 30 (11%) but was higher in group O (43%) than in group 30 (P<0.05). Compared with group O, patients in group 80 experienced more vomiting during the study period 0-24 h (66% vs. 32%; P<0.05) and more nausea during the period 6-24 h (72% vs. 39%; P<0.05). There was no difference between the groups in their risk for PONV, pain scores, opioid consumption, or patient satisfaction. CONCLUSIONS: In this study, supplemental 80% oxygen administration failed to decrease PONV in breast surgery.

Adolescent↗
PubMed2005

Recovery of N100 component of auditory event-related potentials and EEG after cardiac arrest during propofol sedation.

We report on the EEG monitoring of a patient who suffered an episode of postoperative ventricular fibrillation (VF) following coronary artery bypass grafting (CABG). VF initially caused a considerable suppression and slowing of the EEG. The recovery of cerebral function was evaluated by recording both EEG and auditory event related potentials (ERPs). Six hours after the episode of VF, when the patient was asleep but arousable to voice command, the N100 component of the auditory ERPs had recovered to the level measured before the operation, whereas the EEG was still very slow for that level of sedation. This may have been due to VF having less effect on the N100 component than on the background EEG. Our findings suggest that measuring evoked potentials may improve the evaluation of brain function after cardiac arrest.

Aged↗
PubMed2004

Airway pressure release ventilation as a primary ventilatory mode in acute respiratory distress syndrome.

BACKGROUND: Airway pressure release ventilation (APRV) is a ventilatory mode, which allows unsupported spontaneous breathing at any phase of the ventilatory cycle. Airway pressure release ventilation as compared with pressure support (PS), another partial ventilatory mode, has been shown to improve gas exchange and cardiac output. We hypothesized whether the use of APRV with maintained unsupported spontaneous breathing as an initial mode of ventilatory support promotes faster recovery from respiratory failure in patients with acute respiratory distress syndrome (ARDS) than PS combined with synchronized intermittent ventilation (SIMV-group). METHODS: In a randomized trial 58 patients were randomized to receive either APRV or SIMV after a predefined stabilization period. Both groups shared common physiological targets, and uniform principles of general care were followed. RESULTS: Inspiratory pressure was significantly lower in the APRV-group (25.9 +/- 0.6 vs. 28.6 +/- 0.7 cmH2O) within the first week of the study (P = 0.007). PEEP-levels and physiological variables (PaO2/FiO2-ratio, PaCO2, pH, minute ventilation, mean arterial pressure, cardiac output) were comparable between the groups. At day 28, the number of ventilator-free days was similar (13.4 +/- 1.7 in the APRV-group and 12.2 +/- 1.5 in the SIMV-group), as was the mortality (17% and 18%, respectively). CONCLUSION: We conclude that when used as a primary ventilatory mode in patients with ARDS, APRV did not differ from SIMV with PS in clinically relevant outcome.

Adult↗
PubMed2003

Supplemental oxygen for prevention of nausea and vomiting after breast surgery.

BACKGROUND: Administration of supplemental oxygen 80% has been shown to halve the incidence of postoperative nausea and vomiting (PONV). We tested the efficacy of supplemental oxygen 50% in decreasing the incidence of PONV after breast surgery. METHODS: One hundred patients receiving standardized sevoflurane anaesthesia were randomly assigned to two groups: oxygen 30% administration (Group 30); and oxygen 50% administration (Group 50). Oxygen was administered during surgery and for 2 h from the end of surgery. RESULTS: The incidence of PONV over 24 h after surgery showed no difference between the groups: 82% in Group 30 and 89% in Group 50. However, during the postoperative oxygen administration, eight patients vomited in Group 30, compared with none in Group 50 (P<0.05). After oxygen therapy ceased, there was no difference in the incidence of vomiting between the groups. Nausea and need for rescue antiemetics did not differ between the groups. CONCLUSION: The incidence of vomiting decreased during the short postoperative administration of supplemental oxygen 50%. However, perioperative oxygen 50% administration did not prevent PONV over the 24-h follow-up period in patients undergoing breast surgery performed under general anaesthesia.

Anesthesia, General↗
PubMed2002

Customized prediction models based on APACHE II and SAPS II scores in patients with prolonged length of stay in the ICU.

OBJECTIVE: To study customized APACHE II and SAPS II models in predicting hospital death in patients with a prolonged length of stay in the ICU. DESIGN: Prospectively collected database. SETTING: Thirteen ICUs with 5-10 beds in Finnish secondary referral hospitals. INTERVENTIONS: None. MEASUREMENTS AND RESULTS: The database was collected between 1994 and 1999 and included 23,953 ICU admissions. In order to customize the original APACHE II and SAPS II models and to validate the models, the database was randomly divided into customization data ( n=12,064) and into validation data ( n=11,889). Logistic regression analysis was used for customization. As the length of the ICU stay was prolonged, the calibration and discrimination of both customized models worsened gradually in the validation data. Patients whose ICU stay lasted 7 days or longer (1,312 patients) consumed more than one half of all ICU days and TISS-points. Among these patients, goodness-of-fit statistics was 221.5 and 306.3 ( P<0.0001 for both) and the areas under ROC curve 0.65 and 0.62 for the customized APACHE and SAPS models, respectively. The models underestimated the risk of death in the low range and overestimated it in the high range of predicted mortality. On the other hand, both models discriminated well between survivors and non-survivors if the ICU stay was 2 days or less. CONCLUSIONS: Despite customization, the predictive models may not support clinical decision-making in those patients who require a high share of resources. More relevant instruments are needed for the prediction of outcome of patient groups who consume the major part of ICU resources.

APACHE↗
PubMed2000

Intra-institutional prediction of outcome after cardiac surgery: comparison between a locally derived model and the EuroSCORE.

OBJECTIVE: To construct models for predicting mortality, morbidity and length of intensive care unit (ICU) stay after cardiac surgery and to compare the performance of these models with that of the EuroSCORE in two independent validation databases. METHODS: Clinical data on 4592 cardiac surgery patients operated between 1992 and 1996 were retrospectively collected. In order to derive predictive models and to validate them, the patient population was randomly divided into a derivation database (n=3061) and a validation database (n=1531). Variables that were significant in univariate analyses were entered into a backward stepwise logistic regression model. The outcome was defined as mortality within 30 days after surgery, predefined morbidity, and the length of ICU stay lasting >2 days. In addition to the retrospective database, the models were validated also in a prospectively collected database of cardiac surgical patients operated in 1998-1999 (n=821). The EuroSCORE was tested in two validation databases, i.e. the retrospective and prospective one. Hosmer-Lemeshow goodness-of-fit was used to study the calibration of the predictive models. Area under the receiver operating characteristic (ROC) curve was used to study the discrimination ability of the models. RESULTS: The overall mortality in the retrospective and the prospective data was 2 and 1%, and morbidity 22 and 18%, respectively. The created predictive models fitted well in the validation databases. Our models and the EuroSCORE were equally good in discriminating patients. Thus, in the prospective validation database, the mean areas under the ROC curve for our models and for the EuroSCORE were similar, i.e. 0.84 and 0.77 for mortality, 0.74 and 0.74 for morbidity, and 0.81 and 0.79 for the length of intensive care unit stay lasting for 2 days or more, respectively. CONCLUSIONS: Our models and the EuroSCORE were equally good in discriminating the patients in respect to outcome. However, our model provided also well calibrated estimation of the probability of prolonged ICU stay for each patient. As was originally suggested, the EuroSCORE may be an appropriate tool in categorizing cardiac surgical patients into various subgroups in interinstitutional comparisons. Our models may have additive value especially in resource allocation and quality assurance purposes for local use.

Adolescent↗
PubMed2000

Comparison of alfentanil, fentanyl and sufentanil for total intravenous anaesthesia with propofol in patients undergoing coronary artery bypass surgery.

We have studied the pharmacokinetics and pharmacodynamics of alfentanil, fentanyl and sufentanil together with propofol in patients undergoing coronary artery bypass graft surgery (CABG). Sixty patients (age 40-73 yr, 56 male) were assigned randomly to receive alfentanil, fentanyl or sufentanil and propofol. Plasma concentrations of these drugs and times for the plasma concentration to decrease by 50% (t50) and 80% (t80) after cessation of the infusion were determined. Times were recorded to awakening and tracheal extubation. Total dose and plasma concentrations of propofol were similar in all groups. Mean total doses of alfentanil, fentanyl and sufentanil were 443, 45 and 4.4 micrograms kg-1, respectively. Time to awakening did not differ significantly. In patients receiving fentanyl, the trachea was extubated on average 2 h later than in those receiving sufentanil and 3 h later than in those receiving alfentanil (P < 0.05). The t80 of fentanyl was longer (P < 0.05) than that of alfentanil or sufentanil, and there was a linear correlation between the t80 of the opioid and the time to tracheal extubation (r = 0.51; P < 0.01). However, the t50 values for these opioids were similar and did not correlate with recovery time. In conclusion, patients undergoing CABG and who were anaesthetized with fentanyl and propofol needed mechanical ventilatory support for a significantly longer time than those receiving alfentanil or sufentanil and propofol. On the basis of the interindividual variation observed, the time to tracheal extubation was most predictable in patients receiving alfentanil and most variable in patients receiving fentanyl, a finding which may be important if the patients are transferred to a step-down unit on the evening of the operation.

Adult↗
PubMed1999

Effect of low-dose propofol infusion on total-body oxygen consumption after coronary artery surgery.

OBJECTIVE: To investigate the effect of low-dose propofol infusion on total-body oxygen consumption (VO2) after coronary artery bypass grafting (CABG) surgery. DESIGN: A prospective, randomized, placebo-controlled, double-blind study. SETTING: Cardiovascular intensive care unit in a university hospital. PARTICIPANTS: Thirty patients after elective, uncomplicated CABG surgery. INTERVENTION: Patients were administered a continuous infusion of propofol with a fixed rate of 1 mg/kg/h (n = 15) or placebo (n = 15) during the spontaneous rewarming period of approximately 5 hours after surgery. A light level of sedation (Ramsay sedation score > or =2) was maintained by administering small doses of diazepam, 0.1 mg/kg, as required. Morphine, 0.05 mg/kg, was administered for analgesia as required. MEASUREMENTS AND MAIN RESULTS: Total-body VO2 was measured by indirect calorimetry. In addition, shivering (on a five-grade scale), hemodynamics, and plasma catecholamine and serum cortisol concentrations were measured. Diazepam, 5.6+/-7.4 mg (mean +/- standard deviation), was administered to the patients receiving propofol, and 16.1+/-12.2 mg was administered to the patients receiving placebo (p < 0.05). There was no difference in the dose of morphine between the groups (3.2+/-3.9 v 4.2+/-5.5 mg in the propofol and placebo groups, respectively). At any time during the study, VO2 was not different between the groups. VO2 increased from 130+/-29 to 172+/-29 mL/min/m2 in the propofol group and from 118+/-24 to 167+/-27 mL/min/m2 in the placebo group. Mean arterial pressure and heart rate were lower in the propofol group (p < 0.05). Stress hormone levels did not differ between the groups. CONCLUSION: Low-dose propofol infusion and additional diazepam as required does not decrease total-body VO2 compared with a pure diazepam bolus-dose technique when administered for light sedation during the immediate recovery period after CABG surgery.

Adrenergic Agonists↗
PubMed1999

Coating of extracorporeal circuit with heparin does not prevent sequestration of propofol in vitro.

Propofol is sequestered in extracorporeal circuits, but the factors responsible for the phenomenon are mostly unknown. We have compared two extracorporeal circuits (oxygenators, reservoirs and tubings) coated with heparin with two corresponding uncoated circuits for their capacity to sequester propofol in vitro. Three experiments were conducted with each circuit. The circuit was primed with a mixture of Ringer's acetate solution and whole blood, and the study conditions (pump flow, temperature, pH) were standardized. Propofol was added to the solution to achieve a concentration of 2 micrograms ml-1. These studies were followed with concentrations of 10- and 100-fold to assess possible saturation of propofol binding. Serial samples were obtained from the circulating solution for measurement of propofol concentration. Propofol concentrations decreased to 22-32% of the initial predicted concentration of 2 micrograms ml-1 in the circuits (no significant difference between circuits). With greater concentrations, the circuits did not become saturated with propofol, even with the highest predicted concentration of 200 micrograms ml-1. We conclude that propofol was sequestered in extracorporeal circuits in vitro, irrespective of coating the circuit with heparin.

Adhesiveness↗
PubMed1998

Awareness with recall during general anesthesia: incidence and risk factors.

UNLABELLED: We studied the associated factors and incidence of awareness during general anesthesia and the nature of subsequent psychiatric disorders. Patients older than 12 yr undergoing surgery under general anesthesia in a secondary care hospital during 1 yr were included in the study. The doses of anesthetics were calculated for the patients with and without awareness. There were 4818 operations under general anesthesia; 2612 (54%) patients were interviewed. Ten (0.4% of those interviewed) patients were found to have undisputed awareness, and there were nine (0.3%) patients with possible awareness. The doses of isoflurane (P < 0.01) and propofol (P < 0.05) were smaller in patients with awareness. Five patients with awareness underwent a psychiatric evaluation. One patient experienced sleep disturbances afterward, but the other four patients did not have any after effects. In conclusion, awareness is a rare complication of general anesthesia associated with small doses of anesthetics. IMPLICATIONS: In an interview of 2612 patients after general anesthesia, 10 (0.4%) patients with awareness and 9 (0.3%) patients with possible awareness were found. A predisposing factor was small doses of the principal anesthetic. In a psychiatric interview, a large proportion of the patients with awareness were found to have suffered from depression in the past.

Adult↗
PubMed1997

Model-driven closed-loop feedback infusion of atracurium and vecuronium during hypothermic cardiopulmonary bypass.

OBJECTIVE: This study was designed to investigate the performance of a computer-controlled infusion of atracurium and vecuronium during cardiac surgery requiring hypothermic cardiopulmonary bypass. DESIGN: Prospective, randomized study. SETTING: A single university hospital. PARTICIPANTS: Twenty patients scheduled for cardiac surgery. INTERVENTIONS: After induction of anesthesia with fentanyl and diazepam, 10 patients were randomly allocated to receive a bolus of atracurium and 10 patients a bolus dose of vecuronium to facilitate endotracheal intubation. The initial bolus was followed by a computer-controlled closed-loop feedback infusion of atracurium or vecuronium until the patients were transferred to the postoperative intensive care unit. The desired level of neuromuscular blockade, as measured by EMG, was set to 90%. Anesthesia was maintained with a mixture of oxygen and air and either enflurane or halothane. MEASUREMENTS AND MAIN RESULTS: The groups were similar with respect to patient characteristics. Except during hypothermic CPB, the controller kept the neuromuscular blockade near the set point in both groups. During hypothermic CPB the maximal oscillation of muscle relaxation was within 10% from the set point. When CPB was initiated, the mean rates of infusion of the muscle relaxants increased from the pre-CPB values, but the change of the infusion rate was not statistically significant for atracurium. During the remainder of CPB, the infusion requirements of both muscle relaxants were greatly reduced, but rewarming essentially returned the infusion requirements to pre-CPB values. CONCLUSIONS: The computer-controlled infusion can be used for the administration of atracurium and vecuronium during CPB.

Adult↗
PubMed1997

Dexmedetomidine as an anesthetic adjunct in coronary artery bypass grafting.

BACKGROUND: Alpha 2-adrenergic agonists decrease sympathetic tone with ensuing attenuation of neuroendocrine and hemodynamic responses to anesthesia and surgery. The effects of dexmedetomidine, a highly specific alpha 2-adrenergic agonist, on these responses have not been reported in patients undergoing coronary artery bypass grafting. METHODS: Eighty patients scheduled for elective coronary artery bypass grafting received, in a double-blind manner, either a saline placebo or a dexmedetomidine infusion, initially 50 ng.kg-1.min-1 for 30 min before induction of anesthesia with fentanyl, and then 7 ng.kg-1.min-1 unit the end of surgery. Filling pressures, blood pressure, and heart rate were controlled by intravenous fluid and by supplemental anesthetics and vasoactive drugs. RESULTS: Compared with placebo, dexmedetomidine decreased plasma norepinephrine concentrations by 90%, attenuated the increase of blood pressure during anesthesia (3 vs. 24 mmHg) and surgery (2 vs. 14 mmHg), but increased slightly the need for intravenous fluid challenge (29 vs. 20 patients) and induced more hypotension during cardiopulmonary bypass (9 vs. 0 patients). Dexmedetomidine decreased the incidence of intraoperative (2 vs. 13 patients) and postoperative (5 vs. 16 patients) tachycardia. Dexmedetomidine also decreased the need for additional doses of fentanyl (3.1 vs. 5.4), the increments of enflurane (4.4 vs. 5.6), the need for beta blockers (3 vs. 11 patients), and the incidence of fentanyl-induced muscle rigidity (15 vs. 33 patients) and postoperative shivering (13 vs. 23 patients). CONCLUSIONS: Intraoperative intravenous infusion of dexmedetomidine to patients undergoing coronary artery revascularization decreased intraoperative sympathetic tone and attenuated hyperdynamic responses to anesthesia and surgery but increased the propensity toward hypotension.

Adjuvants, Anesthesia↗