Lung function after total intravenous anaesthesia or balanced anaesthesia with sevoflurane.

BACKGROUND: We investigated the effects of total i.v. anaesthesia (TIVA) and balanced anaesthesia (BAL) with sevoflurane on postoperative lung function in patients undergoing surgery in the prone position. METHODS: Sixty patients, aged 21-60 yr, undergoing elective lumbar disc surgery in the prone position were randomly allocated to undergo TIVA (propofol-remifentanil) or BAL (fentanyl-nitrous oxide-sevoflurane). Forced vital capacity (FVC), forced expiratory volume in 1 s, mid-expiratory flow (MEF 25-75), and peak expiratory flow were measured before and after general anaesthesia. RESULTS: Both groups were similar with respect to patient characteristic data and preoperative lung function parameters. Irrespective of the type of anaesthesia administered, lung function parameters decreased after operation, with the decrease in FVC being greater after TIVA than after BAL with sevoflurane. CONCLUSIONS: In patients emerging from general anaesthesia, postoperative reduction in FVC is greater after TIVA than after BAL with sevoflurane.

Pulmonary effects of bupivacaine, ropivacaine, and levobupivacaine in parturients undergoing spinal anaesthesia for elective caesarean delivery: a randomised controlled study.

BACKGROUND: Spinal anaesthesia is the method of choice for elective caesarean delivery, but has been reported to worsen dynamic pulmonary function when using bupivacaine. Similar investigations are lacking for ropivacaine and levobupivacaine. We have therefore compared the pulmonary effects of intrathecal bupivacaine, ropivacaine and levobupivacaine used for caesarean delivery. METHODS: Forced vital capacity, forced expiratory volume in the first second, and peak expiratory flow rate were measured in 48 parturients before and after onset of spinal anaesthesia using either 0.5% bupivacaine 10 mg, 1% ropivacaine 20 mg, or 0.5% levobupivacaine 10 mg. Apgar scores and umbilical arterial pH were recorded. RESULTS: The final level of sensory blockade was not different between groups. Forced vital capacity was significantly decreased with bupivacaine (3.6+/-0.5 L to 3.5+/-0.4 L, P<0.05) and ropivacaine (3.2+/-0.4 L to 3.1+/-0.5 L, P<0.05), but not with levobupivacaine (3.6+/-0.5 L to 3.4+/-0.6 L). Forced expiratory volume during the first second was not decreased in any group. Peak expiratory flow rate was significantly decreased with ropivacaine (5.5+/-1.5 L/s to 5.0+/-1.1 L/s, P<0.05) and levobupivacaine (from 6.0+/-1.1 L/s to 5.2+/-0.9 L/s, P<0.01). Neonatal vital parameters did not differ between the three groups. CONCLUSIONS: Decreases in maternal pulmonary function tests were similar following spinal anaesthesia with bupivacaine, ropivacaine, or levobupivacaine for caesarean delivery. The clinical maternal and neonatal effects of these alterations appeared negligible.

Preoperative stress and anxiety in day-care patients and inpatients undergoing fast-track surgery.

BACKGROUND: To investigate preoperative levels of stress and anxiety in day-care patients and inpatients undergoing surgical interventions. METHODS: Before induction of anaesthesia, the degree of stress and anxiety was assessed in 135 patients using stress and anxiety questionnaires, bio-feedback, physiological measures, and serum levels for stress variables. Questionnaire responses and physiological measures such as arterial pressure, heart rate, skin conductance, cortisol, and catecholamine levels were compared for day-care patients and inpatients. RESULTS: Significant preoperative anxiety was reported by 34 (45.3%) inpatients and 23 (38.3%) day-care patients. Personal responses in stress and anxiety questionnaires and mean values of arterial pressure and heart rate did not differ significantly in day-care patients when compared with inpatients. Correlation between deviations in plasma cortisol concentrations from normal diurnal distribution and anxiety scores and stress scores was also similar, and the relative increase in preoperative stress variables and measures observed in day-care patients and inpatients was also comparable. Bio-feedback measurements revealed significantly higher preoperative skin conductance (P<0.001) in day-care patients than in inpatients, indicating increased vegetative stress responses. CONCLUSIONS: Preoperative anxiety and stress are common in surgical patients. Questionnaires and bio-feedback measurements may help to assess the degree of patients' burdens. Surgeons should be aware of the personal anxiety of patients and consider patient preferences when deciding who should undergo fast-track surgery in day-care.

Bacterial contamination of anaesthetists' hands by personal mobile phone and fixed phone use in the operating theatre.

Following hand disinfection, 40 anaesthetists working in the operating room (OR) were asked to use their personal in-hospital mobile phone for a short phone call. After use of the cell phone, bacterial contamination of the physicians' hands was found in 38/40 physicians (4/40 with human pathogen bacteria). After repeating the same investigation with fixed phones in the OR anteroom 33/40 physicians showed bacterial contamination (4/40 with human pathogen bacteria). The benefit of using mobile phones in the OR should be weighed against the risk for unperceived contamination. The use of mobile phones may have more serious hygiene consequences, because, unlike fixed phones, mobile phones are often used in the OR close to the patient.

Effect of total intravenous anaesthesia and balanced anaesthesia on the frequency of coughing during emergence from the anaesthesia.

BACKGROUND: The effects of total intravenous anaesthesia (TIVA) and balanced anaesthesia (BAL) on coughing during emergence from the general anaesthesia have not yet been compared. METHODS: Fifty patients, aged 18-60 yr, undergoing elective lumbar disk surgery were randomly allocated to undergo TIVA (propofol-remifentanil) or BAL (fentanyl-nitrous oxide-sevoflurane). Extubation was performed in the knee-elbow position, documented on video, and subsequently evaluated by blinded examiners. RESULTS: There was no difference between TIVA and BAL patients with respect to patient characteristics, proportion of smokers, surgical time, or time of emergence. The median number of coughs was significantly lower in the TIVA group (1, range 0-9) than in the BAL group (4, range 0-20, P = 0.007). Mean maximal heart rate and mean maximal arterial pressure measured during emergence were also significantly lower in the TIVA group (P = 0.009 and P = 0.006, respectively). CONCLUSIONS: During emergence from anaesthesia in the knee-elbow position, TIVA is associated with significantly less coughing and reduced haemodynamic response when compared with BAL.

Accidental intracerebroventricular injection of anaesthetic drugs during induction of general anaesthesia.

A 51-year-old patient scheduled for surgery under general anaesthesia was accidentally given remifentanil 150 microg and propofol 1% 10 ml through an intracerebroventricular totally implantable access port placed in the right infraclavicular region, which was mistakenly thought to be an intravenous line. Severe pain in the head and neck caused the mistake to be discovered rapidly, and 20 ml of a mixture of cerebrospinal fluid and the anaesthetic drugs were aspirated from the implantable access port. The patient suffered no apparent adverse neurological sequelae.

Touch sensitivity with sterile standard surgical gloves and single-use protective gloves.

The purpose of this study was to evaluate touch sensitivity and static two-point discrimination of the dominant index and middle finger in 20 anaesthetists wearing no gloves, single-use protective gloves or sterile standard surgical gloves. Semmes-Weinstein filaments were used to measure cutaneous pressure thresholds, and a Two-Point-Discriminator to estimate static two-point discrimination. Wearing gloves significantly reduced touch sensitivity (p < 0.01), but not two-point discrimination. No difference in touch sensitivity or two-point discrimination was found between different types of gloves. The results of our study suggest that the additional cost of sterile standard surgical gloves can not be justified in terms of touch sensitivity.

Significance of working conditions on burnout in anesthetists.

BACKGROUND: The influence of working conditions on the development of burnout syndrome was assessed in anesthetists working at a university hospital. METHODS: Self-reporting questionnaires were used to assess physical health and emotional well-being (Health and Stress Profile), burnout syndrome (Maslach Burnout Inventory) and working conditions (Instrument for Stress-Oriented Task Analysis) in anesthetists. RESULTS: Twenty-three anesthetists (25.8%) appeared to be at risk for burnout, and three anesthetists (3.4%) had already developed full-blown burnout syndrome. Anesthetists at risk for burnout more frequently suffered from limited complexity of work (P=0.001), lacking individual time control (P=0.004), lack of participation possibilities (P=0.012), and had more physical complaints (P=0.017) and greater job dissatisfaction (P=0.002) than did their colleagues with no burnout symptoms. CONCLUSION: Job conditions providing little opportunity to influence work pace and participation contribute to the development of burnout syndrome. Communication and contact with colleagues appear to be an important preventive regulative.

Post-duty psychomotor performance in young and senior anaesthetists.

BACKGROUND AND OBJECTIVE: The level of performance in junior and senior anaesthetists was investigated after 24-h shift working and on-call duties. METHODS: Pre- and post-duty psychomotor function, influence on response time, cognitive function and well-being in 23 individuals (13 junior and 12 senior anaesthetists) was assessed before and after 24-h in-house on-call duty. Subjective perception of tiredness and concentration abilities was estimated by applying a visual analogue scale. RESULTS: The self-assessed tiredness prior to duty was high in both age groups and significantly increased in senior anaesthetists after night duty (P = 0.01). Post-duty impairment of concentration abilities was reported in both groups. Comparing results from pre- and post-duty psychometric testing showed a comparable decline in junior and senior anaesthetists as well. Assessment of burnout showed a significant lack of personal accomplishment in junior anaesthetists as compared to their older colleagues (P = 0.038). Senior anaesthetists judged their contribution to patient well-being significantly higher than did their younger colleagues (P = 0.035). CONCLUSIONS: Although tiredness and subjective impairment of concentration abilities was high in senior anaesthetists after 24-h in-house on-call duty, performance assessed by psychometric testing does not support the hypothesis that senior colleague's performance cannot keep up with routine hospital shift work.

Intraocular pressure during lumbar disc surgery in the knee-elbow position.

Increased intraocular pressure is often implicated in the aetiology of postoperative visual impairment. Such an increase in intraocular pressure has been demonstrated in the prone position. We investigated intraocular pressure in seven patients undergoing lumbar disc surgery in the knee-elbow position with the head resting on a cushion and turned to the side. Measurements were performed in the supine position before induction of anaesthesia and in the knee-elbow position after surgery with the patient still anaesthetised. After a mean (SD) duration of prone positioning of 121 (18) min, mean (SD) intraocular pressure in the nondependent eye was unchanged when compared to the awake state (17.7 (2.4) mmHg vs 18.9 (5.5) mmHg), whereas the intraocular pressure in the dependent eye had significantly decreased (17.0 (3.6) mmHg vs 8.1 (1.8) mmHg; p < 0.01). These results may be important for choosing the optimal position for spinal surgery when an increase in intraocular pressure should be avoided.

Influence of working conditions on job satisfaction in anaesthetists.

BACKGROUND: We studied job satisfaction, physical health, emotional well-being and working conditions in 125 Austrian and Swiss anaesthetists. METHODS: Responses to self-reporting questionnaires were evaluated. Dependent variables included job satisfaction, emotional well-being and physical health. Independent variables included age, sex, marital status, position and working conditions as assessed by the Instrument for Stress-related Job Analysis. RESULTS: Control over work shows a strong effect on job satisfaction in anaesthetists, for example influence on handling tasks (P=0.001), time control (P=0.002) and participation (P=0.001), whereas task demands and task-related problems did not have any effect. Anaesthetists in leading positions and specialists reported lower job satisfaction (P=0.012) than did anaesthetists in non-leading positions. Job satisfaction was associated with better physical health (P=0.001) and better emotional well-being (P=0.005). CONCLUSIONS: Our results suggest that a high level of job satisfaction in anaesthetists correlates with interesting work demands and the opportunity to contribute skills and ideas. To improve job satisfaction, more attention should be paid to improving working conditions, including control over decision-making, and allowing anaesthetists to have more influence on their own work pace and work schedule.

Remifentanil and nitrous oxide reduce changes in cerebral blood flow velocity in the middle cerebral artery caused by pain.

BACKGROUND: Cerebral blood flow is affected by painful stimuli, and analgesic agents may alter the response of cerebral blood flow to pain. We set out to quantify the effects of remifentanil and nitrous oxide on blood flow changes caused by experimental pain. METHODS: We simulated surgical pain in 10 conscious volunteers using increasing mechanical pressure to the tibia. We measured changes in cerebral blood flow velocity in the middle cerebral artery (CBFV(MCA)) caused by the pain, using transcranial Doppler sonography. We gave increasing doses of remifentanil (0.025, 0.05 and 0.1 micro g kg(-1) min(-1)) or nitrous oxide [20%, 35% and 50% end-tidal concentration (FE'(N(2)O))] and compared these effects on blood flow changes. RESULTS: Nitrous oxide increased CBFV(MCA) only when given at 50% FE'(N(2)O). Remifentanil did not affect CBFV(MCA). Pain increased CBFV(MCA). Both agents attenuated this pain-induced change in CBFV(MCA) with the exception of nitrous oxide at 20% FE'(N(2)O). CONCLUSIONS: Inhalation of nitrous oxide or adminstration of remifentanil attenuated pain-induced changes in CBFV(MCA).

Subanesthetic concentration of sevoflurane increases regional cerebral blood flow more, but regional cerebral blood volume less, than subanesthetic concentration of isoflurane in human volunteers.

Both sevoflurane and isoflurane are used in moderate concentrations in neuroanesthesia practice. The limiting factors for using higher concentrations of inhalational anesthetics in patients undergoing neurosurgery are the agents' effects on cerebral blood flow (CBF) and cerebral blood volume (CBV). In particular, an increase in CBV, which is a key determinant of intracranial pressure, may add to the neurosurgical patient's perioperative risk. To compare the effects of a subanesthetic concentration (0.4 minimum alveolar concentration) of sevoflurane or isoflurane on regional CBF (rCBF), regional CBV (rCBV) and regional mean transit time (rMTT), contrast-enhanced magnetic resonance imaging perfusion measurements were made in spontaneously breathing human volunteers. Absolute changes in rCBF, regional CBV, and rMTT during administration of either drug in regions of interest outlined bilaterally in white and grey matter were nonparametrically (Mann-Whitney test) analyzed. Sevoflurane increased rCBF in practically all regions (absolute change, 4.44 +/- 2.87 to 61.54 +/- 2.39 mL/100g per minute) more than isoflurane did (absolute change, 12.91 +/- 2.52 to 52.67 +/- 3.32 mL/100g per minute), which decreased frontal, parietal, and white matter rCBF (absolute change, -1.12 +/- 0.59 to -14.69 +/- 3.03 mL/100g per minute). Regional CBV was higher in most regions during isoflurane administration (absolute change, 0.75 +/- 0.03 to 4.92 +/- 0.16 mL/100g) than during sevoflurane administration (absolute change, 0.05 +/- 0.14 to 3.57 +/- 0.14 mL/100g). Regional mean transit time was decreased by sevoflurane (absolute change, -0.18 +/- 0.05 to -0.60 +/- 0.04 s) but increased by isoflurane (absolute change, 0.19 +/- 0.03 to 0.69 +/- 0.04 s). In summary, regional CBV was significantly lower during sevoflurane than during isoflurane administration, although sevoflurane increased rCBF more than isoflurane, which even decreased rCBF in some regions. For sevoflurane and, even more pronouncedly, for isoflurane, the observed changes in cerebral hemodynamics cannot be explained by vasodilatation alone.

The impact of business cards on physician recognition after general anesthesia.

UNLABELLED: Despite their contribution to overall perioperative treatment of patients, anesthesiologists often remain in anonymity. We evaluated the impact of business cards on physician recognition after general anesthesia. Using a questionnaire, 441 patients were interviewed for recall of the anesthesiologist's name, the surgeon's name, and their overall satisfaction with anesthetic care 6 wk after undergoing surgery during general anesthesia. Of these patients, 155 had and 137 had not randomly received a business card during the preoperative visit, with another 149 patients serving as a control group. Business card recipients responded significantly more frequently than did nonrecipients or patients from the control group (65.8% vs 54.7% vs 53%), with recall of the anesthesiologist's name being significantly more frequent in the Business Card Recipient group (51.5% vs 14.3% vs 11.4%). Patient satisfaction with anesthetic care and recall of the surgeon's name were similar in all groups. The use of a simple tool such as a business card can indeed produce a measurable positive change in physician recognition on the part of the patient. IMPLICATIONS: Anesthesiologists often remain anonymous in everyday clinical practice. Handing a business card to the patient during the preoperative visit increased the postoperative recall of the anesthesiologist's name from 11% to 51%.

Increasing mean airway pressure reduces functional MRI (fMRI) signal in the primary visual cortex.

Changes in both blood flow and blood oxygenation determine the functional MRI (fMRI) signal. In the present study factors responsible for blood oxygenation (e.g., FiO(2)) were held constant so that changes in pixel count would above all reflect changes in regional cerebral blood flow (rCBF). Continuous positive airway pressure (CPAP) breathing at 12 cm H(2)O, which was previously shown to influence rCBF, was applied in human volunteers (n = 19) to investigate the sensitivity of fMRI for changes in rCBF caused by increased mean airway pressure. Increasing the mean airway pressure decreased the pixel count in the primary visual cortex (median (range)): baseline: 219 (58-425) pixels vs. CPAP (12 cm H(2)O): 92 (0-262) pixels). These findings indicate that fMRI is sensitive to detect a reduced rCBF-response in the primary visual cortex. The underlying mechanism is likely to be a reduced basal rCBF due to constriction and/or compression of postcapillary venoles during CPAP breathing. These findings are important for interpreting fMRI results in awake and in artificially respirated patients, in whom positive airway pressure is used to improve pulmonary function during the diagnostic procedure.

Sevoflurane and nitrous oxide increase regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) in a drug-specific manner in human volunteers.

Anesthesia for diagnostic procedures, e.g., MRI measurements, has increasingly used sevoflurane and nitrous oxide in recent years. Sevoflurane and nitrous oxide are known cerebrovasodilatators, however, which potentially interferes with MRI examination of cerebral hemodynamics. To compare the effects of relevant equianesthetic concentrations (0.4 MAC) of both drugs on regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) we used contrast-enhanced magnetic resonance imaging (MRI) perfusion measurement, which has the advantage of providing regional anatomic resolution. Sevoflurane increased rCBF more than did nitrous oxide in all regions except in parietal and frontal gray matter. Nitrous oxide, by contrast, increased rCBV in most of the gray matter regions more than did sevoflurane. In summary we show that, in contrast to nitrous oxide, sevoflurane supratentorially reversed the anterior-posterior gradient in rCBF and typically redistributed rCBF to infratentorial gray matter. In contrast, nitrous oxide increased rCBV more than did sevoflurane. Both inhalational anesthetics had a drug-specific influence on cerebral hemodynamics, which is of importance when interpreting MRI studies of cerebral hemodynamics in anesthetized patients.

Influence of equianaesthetic concentrations of nitrous oxide and isoflurane on regional cerebral blood flow, regional cerebral blood volume, and regional mean transit time in human volunteers.

Nitrous oxide and isoflurane have cerebral vasodilatory effects. The use of isoflurane in neuroanaesthesia is widely accepted, whereas the use of nitrous oxide in neuroanaesthesia is still the subject of debate. In the present study, contrast-enhanced magnetic resonance (MR) perfusion measurement was used to compare the effects of 0.4 MAC nitrous oxide (n=9) and 0.4 MAC isoflurane (n=9) on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV) and regional mean transit time (rMTT) in spontaneously breathing human volunteers. Nitrous oxide increased rCBF and rCBV in supratentorial regions more than did isoflurane. Isoflurane, by contrast, increased rCBF and rCBV in basal ganglia more than did nitrous oxide. An increased rMTT was caused by a relatively greater increase in rCBV than in rCBF supratentorially by isoflurane and infratentorially by nitrous oxide. In conclusion, nitrous oxide increases rCBF and rCBV predominantly in supratentorial grey matter, whereas isoflurane increases rCBF and rCBV predominantly in infratentorial grey matter.

The impact of increased mean airway pressure on contrast-enhanced MRI measurement of regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional mean transit time (rMTT), and regional cerebrovascular resistance (rCVR) in human volunteers.

Contrast-enhanced magnetic resonance imaging (MRI) measurement of cerebral perfusion is a diagnostic procedure increasingly gaining access to clinical practice not only in spontaneously breathing patients but also in mechanically ventilated patients. Effects of increased mean airway pressure on cerebral perfusion are entirely possible. Therefore, the present study used continuous positive airway pressure (CPAP) (12 cm H2O) to study the effects of increased mean airway pressure on cerebral perfusion in volunteers. CPAP significantly reduced regional cerebral blood flow (rCBF) and regional cerebral blood volume (rCBV) but increased regional mean transit time (rMTT) and regional cerebrovascular resistance (rCVR). Active vasoconstriction (e.g., arterial) and/or passive compression of capillary and/or venous vessel areas are the most likely underlying mechanisms. The number of interhemispheric differences in rCBF, rCBV, rMTT, and rCVR found at baseline rose when mean airway pressure was increased. These results, although obtained in volunteers, should be taken into consideration for the interpretation of contrast-enhanced MRI perfusion measurements in mechanically ventilated patients with an increased positive airway pressure.

Low-dose remifentanil increases regional cerebral blood flow and regional cerebral blood volume, but decreases regional mean transit time and regional cerebrovascular resistance in volunteers.

We have used contrast media-enhanced perfusion magnetic resonance imaging MRI to measure regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional mean transit time (rMTT) and regional cerebrovascular resistance (rCVR) in volunteers at baseline and during infusion of remifentanil (0.1 microgram kg-1 min-1). Remifentanil increased rCBF and rCBV in white and grey matter (striatal, thalamic, occipital, parietal, frontal) regions, with a parallel decrease in rMTT in those regions with the exception of occipital grey matter. rCVR was decreased in all regions studied. The relative increase in rCBF was greater than that in rCBV. Cerebral haemodynamics were increased significantly in areas less rich in mu-opioid receptors with a tendency towards more pronounced increases in rCBF and rCBV in pain-processing areas. Furthermore, interhemispheric differences in rCBF, rCBV and rMTT found prior to drug administration were almost eliminated during infusion of remifentanil. We conclude that, apart from direct and indirect cerebrovascular effects of remifentanil, these findings are consistent with cerebral excitement and/or disinhibition.