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Biomedical subjects

P Biro

Publications and source records attributed to P Biro.

At least 19 recordsLinked to original sources
PubMed2001

Laryngeal mask airway and high-frequency jet ventilation for the resection of a high-grade upper tracheal stenosis.

The surgical resection of a high-grade tracheal stenosis presents a special case of a difficult airway. A 20-year-old male was treated for a 45-mm long tracheal stenosis with 60% reduction of the patent airway area beginning 25 mm below the glottis. To avoid manipulations of the affected segment before surgical exposure of the trachea was established, strictly supraglottic ventilation via a laryngeal mask airway was performed. During removal of the stenosis and creation of the anastomosis, transglottic high-frequency jet ventilation (HFJV) is a convenient technique that enables optimal access to the operation field. Changing from HFJV to conventional ventilation after completion of the anastomosis is not necessary, and the jet catheter can be left in place until the end of the anesthesia.

Adult↗
PubMed2001

Comparison of two video-assisted techniques for the difficult intubation.

BACKGROUND: Two recently developed video-optical intubation devices, the video-optical intubation stylet (VOIS) and the angled video intubation laryngoscope (AVIL) were compared for intubation times and success rate in a simulated difficult tracheal intubation setting. METHODS: Thirty anaesthetists were asked to perform 5 intubation attempts with both techniques. Intubation times were recorded and the subjective degree of difficulty and preference for each technique were requested. RESULTS: Intubation time with the VOIS was shorter (17.4+/-6.8 s) than with the AVIL (22.8+/-13.4 s; P=0.0001). Four of the 150 intubation attempts with the AVIL were scored as unsuccessful, due to prolonged intubation time (>60 s). The estimated degree of difficulty was not significantly different. CONCLUSION: In conclusion, both video-assisted intubation devices, the video-optical intubation stylet and the angled video intubation laryngoscope, can be considered to be simple and effective tools which facilitate tracheal intubation and which require only brief instruction and training.

Humans↗
PubMed2001

Safer colonoscopy with patient-controlled analgesia and sedation with propofol and alfentanil.

BACKGROUND: The aim of this study was to assess the efficacy of patient-controlled analgesia and sedation with propofol/alfentanil for colonoscopy compared with continuous drug infusion and conventional nurse-administered medication. METHODS: One hundred fifty patients undergoing colonoscopy on an outpatient basis were randomly assigned to 1 of 3 medication regimens. To maintain blinding, all patients were connected to an infusion pump. Group I patients could self-administer boluses of 4.8 mg propofol and 125 microg alfentanil without restriction. Group II patients received a continuous infusion with 0.048 mg/kg propofol and 0.12 microg/kg alfentanil per minute. Group III patients received intravenous premedication with 0.035 mg/kg midazolam and 0.35 mg/kg meperidine. RESULTS: There were no differences between the groups with respect to pain (visual analogue scale) and procedure time. Patient-controlled analgesia and sedation with propofol/alfentanil (group I) resulted in less of an increase in the transcutaneous partial pressure of carbon dioxide (p = 0.0004) during colonoscopy and less of a decrease in mean arterial blood pressure (p = 0.0021) during recovery, as well as more complete recovery (p = 0.0019) after 45 minutes compared with conventional administration of midazolam/meperidine. Furthermore, patient-controlled analgesia and sedation yielded a higher degree of patient satisfaction than continuous infusion of propofol/alfentanil (p = 0.0033) or nurse-administered midazolam/meperidine (p = 0.0094). CONCLUSIONS: Patient-controlled administration of propofol and alfentanil for colonoscopy may provide a better margin of safety than conventional administration of midazolam and meperidine and results in a higher level of patient satisfaction and shorter recovery.

Alfentanil↗
PubMed2000

Comparison of a new video-optical intubation stylet versus the conventional malleable stylet in simulated difficult tracheal intubation.

Handling and efficacy of a new video-optical intubation stylet were assessed in a simulated difficult tracheal intubation setting and compared with a conventional malleable stylet. Forty-five anaesthetists performed 10 tracheal intubations using both techniques. Laryngoscopy was performed by the observer, who created a grade 3 view according the classification by Cormack and Lehane. The time taken to place the tracheal tube and the final tracheal tube positions were documented. Mean (SD) intubation time for the video-optical stylet was 20.4 (7.7) s and for the malleable stylet 10.2 (3.3) s (p<0.01). With the video-optical stylet the trachea was correctly intubated in all 225 attempts; with the malleable stylet 44 (19.6%) oesophageal and 44 (19.6%) endobronchial intubations occurred (p<0.01). The video-optical intubation stylet enabled us to recognise inappropriate tracheal tube positions and to correct them immediately. This equipment can be considered a reliable and effective tool for management of the difficult airway.

Computer Terminals↗
PubMed2000

Carbon dioxide elimination during high-frequency jet ventilation for rigid bronchoscopy.

Oxygen saturation and carbon dioxide values should be monitored during high-frequency jet ventilation (HFJV). Modern transcutaneous PCO2 (PtcCO2) measurement allows the estimation of ventilation efficiency. We studied how tests of lung function could predict carbon dioxide elimination during HFJV. Lung function tests from 180 adult patients undergoing rigid bronchoscopy were analysed as factors affecting carbon dioxide elimination. The lung function test results showed a significant relationship with the efficiency of carbon dioxide elimination; the greatest impairment of carbon dioxide elimination was found in patients with combined abnormalities of lung function. Further factors associated with difficult carbon dioxide elimination were male gender and elevated body weight. Of the patients investigated, 72% had normal carbon dioxide elimination, whereas in 23% hypercapnia could be avoided only by increasing the driving pressure. The prevalence of abnormal preoperative lung function test results predicts (sensitivity 76%, positive predictive value 27%) impaired carbon dioxide elimination during jet ventilation and rigid bronchoscopy.

Adolescent↗
PubMed2000

Influence of airway-occluding instruments on airway pressure during jet ventilation for rigid bronchoscopy.

We measured changes in airway pressure (Paw) caused by microsurgical instruments introduced into a rigid bronchoscope during high frequency jet ventilation (HFJV). With approval of the institutional Ethics Committee, 10 adults undergoing elective tracheobronchial endoscopy and endosonography during general anaesthesia were investigated. Inflation of an endosonography probe balloon in the left main stem bronchus caused airway obstruction. Pressure measurements proximal and distal to the obstruction were compared after three degrees of obstruction (0%, 50% and 90%) and with two different driving pressure settings. Airway obstruction increased the mean (SD) peak inspiratory pressure (PIP) from 7.5 (2.6) to 9.5 (3.5) mm Hg for 2 atm (P = 0.0008) and from 9.7 (3.7) to 13.0 (5.1) mm Hg for 3 atm (P = 0.0001). Airway obstruction did not alter peripheral PIP (7.2 (4.1) to 7.1 (3.7) mm Hg for 2 atm and 8.8 (4.3) to 9.4 (5.2) mm for 3 atm), but resulted in an end-expiratory pressure (EEP) beyond the narrowing being significantly greater than in the unobstructed airway (2.5 (3.4) to 5.5 (3.7) mm Hg for 2 atm; P = 0.0005) and 3.2 (3.6) to 8.0 (4.3) mm for 3 atm; P < 0.0001). Severe airway narrowing increases inspiratory pressure proximal and expiratory pressure distal to the obstruction in relation to the applied driving pressure. Since the distal EEP never exceeded PIP, even near-total airway obstruction should not cause severe lung distension or barotrauma in subjects with normal lungs.

Aged↗
PubMed1999

Alternative methods for reduction of blood loss during elective orthognathic surgery.

Bimaxillary orthognathic surgery and genioplasty are frequently performed to correct dentoskeletal anomalies in otherwise healthy young patients. Until 1990 homologous blood transfusions were routinely necessary for these procedures. The present study describes a protocol of blood-saving measures that was adopted and tested on a continuous sample of 127 patients treated between 1994 and 1997. The protocol comprises acute normovolemic hemodilution, controlled moderate hypotension, positioning the surgical field above the heart level, cell saving, intraoperative homeostasis, preoperative autologous blood donation, administration of recombinant erythropoietin, and acceptance of a low hematocrit perioperatively. This study shows that homologous blood transfusions may be avoided intraoperatively by following the protocol described.

Blood Loss, Surgical↗
PubMed1998

A formula to calculate oxygen uptake during low flow anesthesia based on FIO2 measurement.

Monitoring of oxygen uptake during general anesthesia would have several benefits, but unfortunately, this is usually not available in the clinical routine situation. The herein proposed formula to calculate oxygen uptake (.VO2) necessitates only the accurate measurement of FIO2 as well as fresh gas flow and composition. Additionally, this method is not affected by the presence of anesthetic gases. The calculation uses the difference in oxygen content between the delivered fresh gas and the resulting FIO2 in the anesthesia circle system. This gap originates from oxygen uptake (that is mainly caused by metabolic oxygen consumption) and is more pronounced if low fresh gas flows are administered. In order to obtain representative results, calculation of .VO2 should be performed only after achievement of respiratory steady state conditions. Due to its simplicity and wide availability, it has the potential to become a valuable extension in anesthesia monitoring during the performance of routine general anesthesia.

Adult↗
PubMed1998

The efficiency of CO2 elimination during high-frequency jet ventilation for laryngeal microsurgery.

UNLABELLED: For adequate and safe use of high-frequency jet ventilation (HFJV), reliable monitoring of the PCO2 status and course is necessary. Because of improved handling and performance, recently available transcutaneous PCO2 monitoring devices such as MicroGas 7650 (Kontron Instruments Medical Sensors, Basel, Switzerland) should enable more effective surveillance of CO2 elimination and, subsequently, better control of subglottic HFJV. Adult patients (n = 164) undergoing laryngeal microsurgery during total i.v. anesthesia were assessed. The resulting transcutaneous PCO2 values, as well as the necessary driving pressure settings, were analyzed to define the CO2 elimination capacity of each patient. Therefore, an individual CO2 elimination coefficient (ECCO2) was calculated. The frequency distribution of the obtained ECCO2 values showed a normal distribution with a median at 0.79 and a range between 0.30 and 2.17. A significant difference in the frequency of obstructive lung disease was found between two patient subpopulations separated by the 25th percentile at an ECCO2 value of 0.63. Other co-factors of CO2 elimination during HFJV were age, gender, and body weight, whereas height and ventilation duration were not involved. We conclude that the individual assessment of ECCO2 enables one to find adequate ventilator settings, resulting in lower airway pressure and less cooling and drying of the tracheobronchial mucosa. IMPLICATIONS: CO2 elimination during high-frequency jet ventilation can be assessed by calculating the CO2 elimination coefficient (ECCO2) of each patient from the required driving pressure and the resulting transcutaneous CO2 partial pressure. The frequency distribution of ECCO2 in a typical laryngological patient population was analyzed, and a value of 0.63 was found to be a characteristic limit between sufficient and difficult CO2 elimination. The individual assessment of ECCO2 enables one to find adequate ventilator settings, resulting in lower airway pressure and less cooling and drying of the tracheobronchial mucosa.

Adult↗
PubMed1997

[The effect of fresh-gas decoupling on respiratory volume. Draegar Sulla 808V anesthesia ventilator].

UNLABELLED: In order to perform accurate low-flow anaesthesia ventilation, it is desirable to avoid the influence of fresh gas flow (FGF) and inspiration duration (ID) on the resulting minute volume (MV). The Sulla 808V anaesthesia ventilator (Draeger, Luebeck, Germany) is originally not equipped with a fresh-gas decoupling (FGD) device. Therefore, changes of FGF and ID settings applied during controlled ventilation may lead to alterations of the resulting MV. Recently, a low-cost FGD device (Carbamed, Bern-Liebefeld, Switzerland) has been developed, which can be inserted into the circle system. We investigated the effect of this device on MV in the Sulla 808V anaesthesia apparatus. METHODS: The performance of a Sulla 808V anaesthesia ventilator was tested with and without a FGD device. During ventilation of a test lung, stepwise changes of tidal volume (400-1000 ml), FGF (0.5-10 l/min), and ID (0.25-0.5) settings were consecutively applied, and the resulting MV was recorded. Correlation and mean prediction error between ventilation parameter settings and MV were calculated. RESULTS: In the presence of a FGD device, the administered MV was not affected by the magnitude of FGF and ID. A mean prediction error (bias) of -3.6 l/min of the resulting MV was observed. Without FGD the bias was only-1.8 l/min, while FGF and ID revealed a pronounced influence on MV. These effects were statistically significant when using FGF exceeding 4 l/min. CONCLUSIONS: The tested FGD device can easily be integrated into the circle system of conventional anaesthesia machines such as the Draeger Sulla 808V, and is available at a reasonable cost. It allows constant ventilation parameters to be maintained that remain unaffected by wide FGF and ID variations. With this FGD the performance of the ventilator can be improved considerably, and low-flow anaesthesia can be used more extensively.

Humans↗
PubMed1997

[The dose-dependent effects of oral premedication with midazolam].

OBJECTIVE: The aim of this study was to examine the psychological effects, well-being and side effects after various doses of oral midazolam medication. METHODS: After informed consent has been obtained and following the approval by the institutional ethical committee, 80 adult patients in the ASA physical status I and II were randomly assigned to one of five different premedication groups: 3.75, 7.5, 11.25, 15 mg midazolam, and placebo. The medication was given in a double-blind fashion 60 min before induction of general anaesthesia for various surgical procedures. At 3 definite stages (before premedication, 30 and 60 min after premedication), blood pressure, heart rate, transcutaneous oxygen saturation and respiratory rate were measured. Sedation and well-being were graded according to a 5-point scale, and the subjective anxiety level was assessed according a visual analogue scale (range 0-100 mm). Anterograde and retrograde amnesia were measured by recall of auditive and visual stimuli. Finally, patients were asked whether in case of future surgery they would prefer the same or a different medication. RESULTS: Demographic data were similar in all groups. There was no significant difference in respiratory rate, oxygen saturation, blood pressure or heart rate. Alertness declined only after 60 min in the groups treated with 7.5 mg and more midazolam. During the entire measurement period, anxiolysis was not different from placebo in any of the midazolam groups. In comparison to placebo, all midazolam groups showed a statistically significant and dose dependent anterograde amnesia for visual stimuli. Subjective well-being scores showed no differences between the groups. Only few side effects were seen following doses of 7.5 mg and higher, including ptosis, strabismus, diplopia, speech disorders, disorientation and vertigo. The majority of patients in all groups indicated a wish for the same medication in case of future anaesthesia for surgical interventions. CONCLUSIONS: Midazolam administered orally prior to surgical procedures showed marked interindividual variability. Sedation and amnesia were dose-dependent and were evaluated by the patients as acceptable. Anxiolysis was not significantly different from placebo. A dose of 7.5 mg midazolam showed the best relation between desirable and undesirable effects. Adequate attention given to the patient by the anaesthesiologist prior to surgery seems to be as important and beneficial as oral medication with midazolam.

Administration, Oral↗
PubMed1996

[Prevention and treatment of postoperative nausea and vomiting with 5-HT3-receptor blockers].

Since there continues to be a high incidence of postoperative nausea and vomiting associated with many types of surgery, and the standard antiemetics often do not achieve satisfactory results, there have been attempts to use the 5-HT3 antagonists. This group of substances is relatively new, but has already been used successfully as an antiemetic during chemotherapy. To date, results are on hand for four different 5-HT3 receptor blockers: ondansetron, tropisetron, granisetron and dolasetron. Applied intravenously, all four have been effective both in prophylaxis and also as therapy for postoperative emesis. Except for ondansetron, there is so far no definitely clear knowledge about the lowest possible effective dosage. The entire group is well tolerated: only occasional and minor side effects have been reported. Even though not all the hopes originally set in the 5-HT3 group of antagonists have been fulfilled, progress has nevertheless been achieved. Especially noteworthy points are a positive cost-effectiveness relationship of these drugs and their appropriate use in case of the proper indications.

Antiemetics↗