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Biomedical subjects

P H Tonner

Publications and source records attributed to P H Tonner.

At least 19 recordsLinked to original sources
PubMed2006

Comparison of LMA Unique, Ambu laryngeal mask and Soft Seal laryngeal mask during routine surgical procedures.

BACKGROUND AND OBJECTIVE: This study was performed to compare three disposable airway devices, the LMA Unique (LMA-U), the Ambu laryngeal mask (Ambu LM) and the Soft Seal laryngeal mask (Soft Seal LM) for elective general anaesthesia during controlled ventilation in non-paralysed patients. METHODS: One hundred and twenty ASA I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the LMA-U (n = 40), Ambu LM (n = 40) or Soft Seal LM (n = 40) groups, respectively. Patients were comparable with respect to weight and airway characteristics. A size 4 LMA was used in all patients and inserted by a single experienced anaesthesiologist. Oxygenation, overall success rate, insertion time, cuff pressure and resulting airway leak pressure were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness. RESULTS: Time of insertion was shortest with the Ambu LM, while failure rates were comparable with the LMA-U, the Ambu LM and the Soft Seal LM (median 19 s; range 8-57 s; success rate 100% vs. 14; 8-35; 97% vs. 20; 12-46; 95%). Insertion was judged 'excellent' in 75% of patients in the LMA-U group, in 70% of patients in Ambu LM group and in 65% of patients in the Soft Seal LM group. There was no difference between devices with respect to postoperative airway morbidity at 6 h or 24 h following surgery. CONCLUSIONS: All three disposable devices were clinically suitable with respect to insertion times, success rates, oxygenation, airway and leak pressures, as well as to subjective handling and postoperative airway morbidity.

Air Pressure↗
PubMed2006

Monitoring of cerebral oxygenation with near infrared spectroscopy and tissue oxygen partial pressure during cardiopulmonary resuscitation in pigs.

BACKGROUND AND OBJECTIVE: The present study was designed to compare cerebral oxygenation measured with near infrared spectroscopy and local brain tissue oxygen partial pressure, respectively, in pigs during cardiopulmonary resuscitation. Since tissue overlying the brain may have an impact on near infrared spectroscopy readings, we tested whether optode placement on intact skin or on the skull yielded comparable results. METHODS: Twelve healthy pigs were anaesthetized and subjected to continuous haemodynamic, near infrared spectroscopy and brain tissue oxygen partial pressure monitoring. After 4 min of untreated ventricular fibrillation, cardiopulmonary resuscitation was started and arginine vasopressin was administered repeatedly three times. Near infrared spectroscopy values recorded were both the tissue oxygenation index and the tissue haemoglobin index as well as relative changes of chromophores (haemoglobin and cytochrome oxidase). Four animals served as control and were measured with both near infrared spectroscopy optodes mounted on the intact skin of the forehead, while in the remaining eight animals, one near infrared spectroscopy optode was implanted directly on the skull. RESULTS: Near infrared spectroscopy readings at the skin or at the skull differed consistently throughout the study period. After arginine vasopressin administration, near infrared spectroscopy values at the different locations showed a transient dissociation. In contrast to near infrared spectroscopy measured on intact skin, near infrared spectroscopy readings obtained from skull showed a significant correlation to brain tissue oxygen partial pressure values (r = 0.67, P < 0.001). CONCLUSION: Near infrared spectroscopy readings obtained from skin and skull differed largely after vasopressor administration. Near infrared spectroscopy optode placement therefore may have an important influence on the tissue region investigated.

Animals↗
PubMed2006

The influence of xenon on regulation of the autonomic nervous system in patients at high risk of perioperative cardiac complications.

BACKGROUND: As xenon anaesthesia (XE) does not produce haemodynamic depression its use may be of benefit in patients at high risk of intraoperative haemodynamic instability and perioperative cardiac complications. XE (n=22) was compared with total i.v. anaesthesia (TIVA, n=22) for differences in autonomic regulation, peri- and postoperative performance. METHODS: Patients undergoing abdominal aortic surgery were studied at five events: T1: baseline awake; T2: anaesthesia induction; T3: before aortic cross-clamping; T4: after aortic cross-clamping; T5: after aortic declamping. T3-T5: end-tidal xenon concentration 60 (5)%. Intraoperative analysis: heart rate, heart rate variability, blood pressure and cardiac output. Postoperative analysis: 24 h Holter ECG, intensive care unit and hospital stay, and patient's outcome after 6 months. RESULTS: XE in contrast to TIVA increased parasympathetic and decreased sympathetic activity. Median low to high frequency decreased significantly in the XE group after start of XE (P<0.05) and remained significantly lower during all events after start of XE as compared with TIVA (P=0.0001). After start of XE heart rate of these patients was significantly lower as compared with TIVA (P=0.04). Cardiac output increased significantly in TIVA after aortic declamping (P<0.05). Outcome parameters did not differ significantly between groups. CONCLUSIONS: XE patients demonstrated lower sympathetic and higher parasympathetic activity as compared with TIVA patients. This was reflected by significant differences in haemodynamics but did not correlate with a better postoperative outcome. Thus, it remains controversial whether XE provides benefits in high risk patients.

Aged↗
PubMed2006

Classic electroencephalographic parameters: median frequency, spectral edge frequency etc.

Even today many anaesthesiologists rely on parameters of the autonomic nervous system, such as blood pressure and heart rate to decide if a patient is adequately anaesthetized. It is thought that the electroencephalogram (EEG) may provide more information on the state of anaesthesia. Because full EEG analysis is not possible in the operating room, processed EEG parameters have been developed comprising complex information into a single value. Time and frequency domain parameters are calculated. The power spectrum results from a Fourier analysis and can be described by parameters such as median frequency, spectral edge frequency and others. It was noted, however, that anaesthetics at low doses increase frequency of the EEG, whereas at high doses the EEG is depressed. This biphasic response makes it difficult to clearly distinguish the exact anaesthetic state of a patient. Median frequency and spectral edge frequency have been studied in numerous studies. However, no sole indicator has been derived from the EEG that could serve as a descriptor of anaesthetic depth.

Alpha Rhythm↗
PubMed2006

Propofol/remifentanil vs sevoflurane/remifentanil for long lasting surgical procedures: a randomised controlled trial.

We compared the haemodynamics, emergence and recovery characteristics of total intravenous anaesthesia using propofol/remifentanil with sevoflurane/remifentanil anaesthesia, under bispectral index guidance, in 103 patients undergoing surgical procedures lasting > 3.5 h. Time to tracheal extubation was significantly shorter in the propofol group than in the sevoflurane group (mean (SD) 8.3 (3.5) min vs 10.8 (4.6) min, respectively; p = 0.0024), but further recovery was comparable in both groups. There were no significant differences in haemodynamic parameters, intensity of pain or postoperative nausea and vomiting. During and after anaesthesia of comparable depth for long lasting surgical procedures, both propofol/remifentanil and sevoflurane/remifentanil enable haemodynamic stability and fast emergence. The shorter time to extubation in the propofol group does not offer a relevant clinical advantage.

Abdomen↗
PubMed2005

Balanced anaesthesia today.

An 'ideal' anaesthetic can be approached by using a combination of different compounds. A variety of anaesthetic techniques has been described to ensure safe administration and an early recovery with high patient satisfaction. In particular, the inhalational anaesthetics desflurane and sevoflurane, with their rapid pharmacokinetics, re-established the notion of balanced anaesthesia as an equivalent, well-controllable technique. With the choice of anaesthetics and anaesthetic adjuvants clinically available today, especially the combination of a volatile anaesthetic with a short-acting opioid, balanced anaesthesia represents a big step towards an ideal anaesthetic.

Analgesia↗
PubMed2005

Arginine vasopressin reduces cerebral oxygenation and cerebral blood volume during intact circulation in swine---a near infrared spectroscopy study.

BACKGROUND AND OBJECTIVE: The aim of the present study was to investigate the impact of arginine vasopressin (AVP), a drug currently under investigation for use during cardiopulmonary resuscitation, on cerebral oxygenation and cerebral blood volume (CBV) in pigs with intact systemic circulation using near infrared spectroscopy. METHODS: Nine healthy pigs were anaesthetized and subjected to invasive haemodynamic monitoring as well as to non-invasive determination (with near infrared spectroscopy) of changes in the Tissue Oxygenation Index (TOI is the ratio of oxygenated to total tissue haemoglobin), Tissue Haemoglobin Index (THI, representing CBV) and cytochrome oxidase (deltaCytOx, representing the balance of intracellular oxygen supply). RESULTS: At both 3 and 5 min after AVP administration, TOI, THI and deltaCytOx were significantly (P < 0.001) reduced compared to baseline, while cerebral perfusion pressure increased significantly (P < 0.001). The effects of AVP on TOI and THI lasted longer than on deltaCytOx. There were no significant changes with respect to the intracranial pressure throughout the study period. CONCLUSIONS: No improvement of cerebral oxygenation was detected after AVP administration in swine with an intact systemic circulation. In contrast to recently published investigations, AVP provoked a sustained drop in indices of cerebral oxygenation and CBV.

Animals↗
PubMed2005

Pseudocholinesterase activity increases and heart rate variability decreases with preoperative anxiety.

BACKGROUND AND OBJECTIVE: The objective of this study was to determine the influence of preoperative anxiety on the activity of plasma cholinesterase and heart rate (HR) variability. METHODS: A total of 50 subjects were studied, 25 male patients one day preoperatively and 25 male volunteers without surgical intervention as a control group. Blood samples were taken to determine plasma cholinesterase activity. HR variability was recorded for a period of 256 beat-to-beat intervals and analysed by frequency domain analysis into very low frequency (VLF: 0.02-0.04 Hz), low frequency (LF: 0.04-0.15 Hz) and high frequency (HF: 0.15-0.4 Hz). LF/HF ratio and total power over the 0.02-0.4 Hz range were calculated. Anxiety levels were assessed using the hospital anxiety and depression scale, the self-rating anxiety scale and a visual analogue scale. RESULTS: The patient group had significantly higher anxiety scores. Plasma cholinesterase activity was significantly higher in patients vs. controls (6646 vs. 5324 units L(-1)). Total power, LF and HF were significantly lower in the patients (1489 vs. 2581 ms2; 656 vs. 1186 ms2; 491 vs. 964 ms2, respectively). CONCLUSIONS: Preoperative anxiety increases plasma cholinesterase activity and decreases HR variability.

Adolescent↗
PubMed2005

A comparison of the proseal laryngeal mask airway, the laryngeal tube S and the oesophageal-tracheal combitube during routine surgical procedures.

BACKGROUND AND OBJECTIVE: This study was performed to compare three supraglottic airway devices: the ProSeal laryngeal mask airway (PLMA), the laryngeal tube S (LTS) and the oesophageal-tracheal combitube (OTC) during routine surgical procedures. METHODS: Ninety American Society of Anesthesiologists (ASA) I-III patients scheduled for routine minor obstetric surgery were randomly allocated to the PLMA (n = 30), the LTS (n = 30) or the OTC (n = 30) group, respectively. The overall success rate, insertion time, cuff pressures and resulting airway leak pressures were determined as well as a subjective assessment of handling and the incidence of sore throat, dysphagia and hoarseness were performed. RESULTS: Insertion time until the first adequate ventilation was significantly (P < 0.0001) shorter in the PLMA (median 29 s; 25-75th percentile 25-48 s; range 10-161 s; success rate 100%) and in the LTS group (38 s; 30-44 s; 13-180 s; 100%) compared to the OTC group (75 s; 48-98 s; 35-180 s; 90%). In vivo cuff pressures and airway leak pressures increased with the inflating cuff volume in all devices and were highest in the OTC group. Postoperatively, patients in the PLMA and the LTS group complained significantly less about sore throat (P < 0.001 and 0.05) and dysphagia (P < 0.001 and 0.02) compared to the OTC group, while there was no difference regarding the incidence of hoarseness. Subjective assessment of handling was comparable with the PLMA and the LTS, but inferior with the OTC. CONCLUSIONS: In conclusion, both PLMA and LTS proved to be suitable for routine surgical procedures and proved to be superior to the OTC which cannot be recommended for routine use.

Blood Pressure↗
PubMed2005

Comparison of xenon-based anaesthesia compared with total intravenous anaesthesia in high risk surgical patients.

Xenon, a noble gas with anaesthetic and analgesic properties, has gained renewed interest due to its favourable physical properties which allow a rapid emergence from anaesthesia. However, high costs limit its use to a subset of patients who may benefit from xenon, thereby offsetting its costs. To date, there are only limited data available on the performance of xenon in high risk patients. We studied 39 patients with ASA physical status III undergoing aortic surgery. The patients were randomly assigned to either a xenon (Xe, n = 20) or a TIVA (T, n = 19) group. Global cardiac performance and myocardial contractility were assessed using transoesophageal echocardiography, and myocardial cell damage with troponin T and CK-MB. Echocardiographic measurements were made prior to xenon administration, following xenon administration, and after clamping of the abdominal aorta, after declamping and at corresponding time points in the TIVA group. Laboratory values were determined repeatedly for up to 72 h. Data were analysed using two-way anova factoring for time and anaesthetic agent or with ancova comparing linear regression lines. No significant differences were found in global myocardial performance, myocardial contractility or laboratory values at any time during the study period. Mean (SEM) duration of stay on the ICU (xenon: 38 +/- 46 vs. TIVA 25 +/- 15 h) or in hospital (xenon: 14 +/- 12 vs. TIVA 10 +/- 6 days) did not differ significantly between the groups. Although xenon has previously been shown to exert superior haemodynamic stability, we were unable to demonstrate an advantage of xenon-based anaesthesia compared to TIVA in high risk surgical patients.

Aged↗
PubMed2004

[Procedure optimization in hospital management].

Starting January 1st 2004 the German diagnosis-related group (DRG) system was established for in-patient cases. Consequently, the detection and realization of cost-saving potentials are becoming more and more important. For a successful future, efficient allocation of resources is essential. Economically, anaesthesia-related time delays during perioperative work-flow should be minimized. Since numerous entities contribute to perioperative care, it is extremely complex to analyze and optimize this process flow. In this publication single steps leading to an optimized perioperative process flow will be presented: documentation of predefined time points, calculation of relevant time intervals and analysis of key numbers for complex settings. Single steps of the given process analysis will be demonstrated using data from surgical patients at the University Hospital Schleswig-Holstein, Campus Kiel. The attached data collection sheets can be used by interested hospital departments and are meant to serve as a template for further process analyses. Based on the shown analysis, an example will be given to develop an optimized work-flow as a standard operating procedure (SOP). The implementation of the SOP module in an interdisciplinary clinical pathway (CP), which defines efficient medical care from admission to discharge, is mainly responsible for decreased process costs but increased quality of care.

Anesthesia Department, Hospital↗
PubMed2004

[Analgesia and sedation in intensive care medicine].

Sedation and analgesia are relevant aspects for the adequate treatment of patients in an intensive care unit. Recent drug developments and new strategies for ventilation provide improved sedation management allowing better adaptation to the clinical background and individual needs of the patient. This article provides an overview on the application of different substance groups. Focus is placed on newly developed pharmaceuticals such as dexmedetomidine. Another aspect is scoring system-related and EEG-based monitoring of depth of sedation. Modern concepts of analgesia and sedation for ICU patients have been developed based on the interaction of different parameters such as adaptive sedation and analgesia management (ASAM).

Analgesia↗