Selective unilateral spinal anaesthesia for outpatient knee arthroscopy using real-time monitoring of lower limb sympathetic tone.

Selective unilateral spinal anaesthesia is a useful approach for ambulatory lower limb surgery because it allows more rapid home discharge compared to bilateral block. Infrequent use is due to the fact that obtaining selective unilateral block can be difficult, requiring attention to technique. We present a method with a high success rate that uses real-time monitoring of the sympathetic activity of the legs. In this prospective study, 56 patients scheduled for ambulatory knee arthroscopy had spinal anaesthesia in the lateral recumbent position, with hyperbaric bupivacaine 0.5% injected at 0.33 ml/min up to a maximum dose of 5 mg. Sympathetic tone of the legs was monitored by plantar electrical dermal resistance. The clinical effect was assessed by loss of sensation and muscle strength. The haemodynamic course and adverse events were monitored. The motor block was strictly unilateral in 55 patients (98%) and the sensory block was strictly unilateral in 53 patients (94%). The median decrease in systolic blood pressure was 6 mmHg. The time from subarachnoid puncture to arrival in the recovery room was 73±23 minutes; the duration of stay in the recovery room was 70±30 minutes. Three patients with a well-established block of adequate extent required conversion to general anaesthesia because of tourniquet pain. Urinary retention only occurred in the sole patient with bilateral block. This method of performing selective unilateral spinal anaesthesia using real-time monitoring of sympathetic tone of the legs has a high success rate and is associated with rapid eligibility for home discharge.

Transfer of airway skills from manikin training to patient: success of ventilation with facemask or LMA-Supreme(TM) by medical students.

During emergency care, the ability to ventilate the patient's lungs is a crucial skill. Supraglottic airway devices have an established role in emergency care, and manikin trials have shown that placement is easy even for inexperienced users. However, there is current discussion as to what extent these results can be transferred to patients. We studied the transfer of skills learnt on a manikin to the clinical situation in novice medical students during their anaesthesia rotation. They were required to ventilate the lungs of a manikin using a facemask and then position a supraglottic airway device (LMA-Supreme™) and ventilate the lungs. This process was then repeated on anaesthetised patients, with standard ventilator settings to assess adequacy of ventilation. Sixty-three students participated in the manikin study. The success rate for ventilating the lungs was 100% for both devices, but the mean (SD) time to achieve successful ventilation was 27.8 (24.4) s with the facemask compared with 38.6 (22.0) s with the LMA-Supreme (p = 0.008). Fifty-one of the students progressed to the second part of the study. In anaesthetised patients, the success rate for ventilating the lungs was lower for the facemask, 27/41 (66%) compared with the LMA-Supreme 37/41 (90%, p = 0.006). For 26 students who succeeded with both devices, the tidal volume was lower using the facemask, 431 (192) ml compared with the LMA-Supreme 751 (221) ml (p = 0.001), but the time to successful ventilation did not differ, 60.0 (26.2) s vs 57.3 (26.6) s (p = 0.71). We conclude that the results obtained in manikin studies cannot be transferred directly to the clinical situation and that guidelines should take this into account. Based on our findings, a supraglottic airway device may be preferable to a facemask as the first choice for inexperienced emergency caregivers.

Surgical pleth index-guided remifentanil administration reduces remifentanil and propofol consumption and shortens recovery times in outpatient anaesthesia.

BACKGROUND: The surgical pleth index (SPI) is an index based on changes in plethysmographic characteristics that correlate with the balance between the sympathetic and parasympathetic nervous system. It has been proposed as a measure of the balance between nociception and anti-nociception. The goal of this study was to test whether it could be used to titrate remifentanil in day-case anaesthesia. METHODS: A total of 170 outpatients were given total i.v. anaesthesia with propofol and remifentanil. The patients were randomized to have the remifentanil dose either adjusted according to the SPI (SPI group) or to clinical parameters (control group). The propofol dose was adjusted according to entropy in both groups. The consumption of anaesthetic drugs, recovery times, and complications were compared. RESULTS: The mean [standard deviation (SD)] remifentanil and propofol infusion rates in the SPI and control groups were 0.06 (0.04) vs 0.08 (0.05) µg kg(-1) min(-1) and 6.0 (2.1) vs 7.5 (2.2) mg kg(-1) h(-1), respectively (both P<0.05). The mean (SD) times to eye opening were -0.08 (4.4) and 3.5 (4.3) min and to extubation were 1.2 (4.4) and 4.4 (4.5) min in the SPI and control groups, respectively (both P<0.05). There was no difference between the groups with regard to satisfaction with the anaesthetic or intensity of postoperative pain. No patient reported intraoperative awareness. CONCLUSIONS: Adjusting the remifentanil dosage according to the SPI in outpatient anaesthesia reduced the consumption of both remifentanil and propofol and resulted in faster recovery.

The use of the Foley Airway Stylet Tool® to guide tracheal intubations through an intubating laryngeal mask airway.

BACKGROUND: Blind insertion of endotracheal tubes through the intubating laryngeal mask airway (ILMA) is unsuccessful in almost 50% of cases on the first attempt, with an overall success rate of approximately 90%. We used a portable fiber optic device (Foley Airway Stylet Tool® FAST) to detect the reasons for failed intubations and tested its use in facilitating endotracheal tube placement. METHODS: Thirty patients without anticipated intubation difficulties participated in the study. The fiber optic device was fastened with its tip at the end of the endotracheal tube, and both instruments were advanced through the previously inserted ILMA past the lifting bar. The view was scored in the following manner: I, full view of laryngeal inlet; II, partial vocal cords, arytenoids, epiglottis; III, epiglottis; IV, no laryngeal structures identifiable. The ILMA was adjusted for the best obtainable view, which was scored, and the endotracheal tube was inserted. RESULTS: The initial laryngeal view was I in four patients, II in eighteen patients, III in one patient and IV in seven patients. The best view after corrective maneuvers was I in twenty-seven patients, II in two patients and IV in one patient. First attempt tracheal intubations were successful in twenty-seven (90%) patients; two patients required a second attempt. CONCLUSION: A grade II view or worse indicated misalignment of the ILMA with the glottis. An endotracheal tube inserted blindly through the misaligned ILMA will impinge on and potentially damage laryngeal structures. The use of a portable fiber optic device can help reduce the failure rate of endotracheal intubations by utilizing ILMA in emergent situations.

Influence of intrinsic noise generated by a thermotesting device on thermal sensory detection and thermal pain detection thresholds.

Various factors can influence thermal perception threshold measurements and contribute significantly to unwanted variability of the tests. To minimize this variability, testing should be performed under strictly controlled conditions. Identifying the factors that increase the variability and eliminating their influence should increase reliability and reproducibility. Currently available thermotesting devices use a water-cooling system that generates a continuous noise of approximately 60 dB. In order to analyze whether this noise could influence the thermal threshold measurements we compared the thresholds obtained with a silent thermotesting device to those obtained with a commercially available device. The subjects were tested with one randomly chosen device on 1 day and with the other device 7 days later. At each session, heat, heat pain, cold, and cold pain thresholds were determined with three measurements. Bland-Altman analysis was used to assess agreement in measurements obtained with different devices and it was shown that the intersubject variability of the thresholds obtained with the two devices was comparable for all four thresholds tested. In contrast, the intrasubject variability of the thresholds for heat, heat pain, and cold pain detection was significantly lower with the silent device. Our results show that thermal sensory thresholds measured with the two devices are comparable. However, our data suggest that, for studies with repeated measurements on the same subjects, a silent thermotesting device may allow detection of smaller differences in the treatment effects and/or may permit the use of a smaller number of tested subjects. Muscle Nerve 40: 257-263, 2009.

Laryngoscopic versus intubating LMA guided tracheal intubation by novice users--a manikin study.

AIM OF THE STUDY: Airway control is a potentially lifesaving procedure but tracheal intubation by direct laryngoscopy is difficult. This pilot study was conducted to determine whether tracheal intubation was more rapid and the success rate higher using an intubating laryngeal mask airway. MATERIAL AND METHODS: The success rates of 119 medical students without prior airway management experience in ventilating and then intubating the trachea of a Laerdal Airway Management Trainer with two different methods were compared. The methods were bag-mask ventilation (BM-V) followed by laryngoscopic intubation (LG-TI), and intubating laryngeal mask ventilation (ILMA-V) followed by ILMA-guided tracheal intubation (ILMA-TI). After an introductory lecture and demonstration, each student was allowed three attempts to intubate using each method in random order. RESULTS: All participants were successful with BM-V and ILMA-V on the first attempt. Laryngoscopic tracheal intubation was achieved by 60 (50.4%), 31 (26.1%) and 12 (10.1%) participants on the first, second and third attempt, respectively, while 16 (13.4%) failed in all three attempts. In the ILMA-TI group, 107 (90.0%), 10 (8.4%) and 2 (1.6%) succeeded on the first, second and third attempt, respectively. None failed. The intergroup difference is highly significant (p<0.001). Male participants were more successful with LG-TI than female (p<0.01), but not with ILMA-TI. CONCLUSION: Laryngoscopic orotracheal intubation is difficult for the untrained, but all participants were successful with ILMA-TI. These data suggest that alternative devices such as the ILMA should be included in the medical school curriculum for airway management.

Effects of mivacurium on the diaphragm evaluated by cervical magnetic stimulation of the phrenic nerves.

BACKGROUND AND OBJECTIVE: Non-depolarizing neuromuscular blocking agents have differential effects on the diaphragm and skeletal muscles. We employed a new method to study the effects of mivacurium on the diaphragm and compared the results obtained with this method with published data. METHODS: Anaesthesia was induced and maintained with propofol and alfentanil and the trachea was intubated after topical anaesthesia. Contractions of the diaphragm were induced by cervical magnetic stimulation of the phrenic nerves and quantified by measuring airway pressure responses. The neuromuscular effects on skeletal muscles were measured by acceleromyography of the adductor pollicis muscle. Mivacurium (0.15 mg kg(-1)) was injected and neuromuscular responses were recorded until the effects had waned. RESULTS: Eleven male and 10 female patients (ASA I-II; 57 +/- 16 yr; 78 +/- 13 kg; mean +/- standard deviation) participated. Median maximal reduction of twitch response was less (P < 0.05) for the diaphragm (89%) than for the adductor pollicis (100%). Time to 25% recovery was shorter for the diaphragm than for the adductor pollicis (8.8 +/- 2.2 min vs. 22.6 +/- 5.0 min, P < 0.05). The difference between the recovery index of the diaphragm (7.3 min (3.6-18.4)) and the adductor pollicis (8.2 min (4.4-20.9) (median (range)) just missed our chosen level of statistical significance (P = 0.06). The recovery time to train-of-four 0.8 was shorter for the diaphragm (median and 95% confidence interval 25.1 +/- 10.2 min) than for the adductor pollicis (median and 95% confidence interval 37.5 +/- 9.4 min, P < 0.05). CONCLUSIONS: The duration of the clinical effect of mivacurium on the diaphragm is markedly shorter than on the adductor pollicis muscles but there was only a small difference in the recovery index of the two muscles. These effects and the time courses determined with the new method closely resemble the results obtained with different methods in other studies.

Mood change after anaesthesia with remifentanil or alfentanil.

BACKGROUND AND OBJECTIVE: There are anecdotal reports of dysphoria occurring in patients on the first day after anaesthesia with remifentanil. This study was performed to investigate this allegation and to find a possible relationship to postoperative shivering or to nausea and vomiting. METHODS: Patients undergoing otorhinolaryngeal surgery took part in a prospective, randomized, double-blind study comparing total intravenous anaesthesia with propofol (2 mg kg(-1) bolus injection then 100 microg kg(-1) min(-1)) and remifentanil (1 microg kg(-1) bolus then 0.1-0.5 microg kg(-1) min-1) or alfentanil (30 microg kg(-1) bolus then 0.16-0.83 microg kg((-1) min(-1)). The patients were carefully insulated and actively warmed by convective heating and rectal temperature was monitored continuously. Postoperative shivering was graded on a three-point scale, and the cumulative incidence of nausea and vomiting were registered at 24 h after surgery. Pre- and postoperative mood was measured with the von Zerssen mood scale (Befindlichkeits-Skala) and changes tested for significance. High scores reflect discontent and dysphoria. RESULTS: The data of 98 patients (49 in each group, ASA I-II, age 42 +/- 13 yr, anaesthesia time 141 +/- 60 min; mean +/- SD; intergroup P values > 0.1) were evaluated. Core temperature did not change perioperatively (before 36.6 +/- 0.2 degrees C; after 36.8 +/- 0.3 degrees C, inter- and intragroup P > 0.1). The incidence of nausea was the same in each group; vomiting occurred with equal frequency (6/49 vs. 7/49). Shivering was significantly more frequent after remifentanil (41% vs. 10%, P < 0.001). The patients' mood remained stable after remifentanil but worsened after alfentanil (von Zerssen score from 9.3 +/- 2.5 to 13.9 +/- 3.6; mean +/- 95% confidence intervals; P < 0.01). DISCUSSION: Postoperative shivering was more frequent after remifentanil but was unrelated to intraoperative heat loss. Contrary to preliminary informal observations, there was no evidence that remifentanil caused postanaesthetic dysphoria on the day one after surgery.

Neuromuscular effects of rapacuronium on the diaphragm and skeletal muscles in anaesthetized patients using cervical magnetic stimulation for stimulating the phrenic nerves.

BACKGROUND AND OBJECTIVE: Non-depolarizing neuromuscular blocking agents have a shorter duration of action on the diaphragm than on skeletal muscles. It was to be tested if this also held true for rapacuronium, a short-acting, amidosteroid non-depolarizing neuromuscular blocker, lately withdrawn from the market, using a novel technique for stimulating the diaphragm and assessing its function. METHODS: Anaesthesia was induced with propofol 2 mg kg(-1) and remifentanil 1 microg kg(-1), and the trachea was intubated after topical anaesthesia. Rapacuronium was given at a dose of 1.5 mg kg(-1). The diaphragm was stimulated by cervical magnetic stimulation of the phrenic nerves (2 Tesla, single coil) and airway pressure responses were measured at the endotracheal tube connector. The neuromuscular effects at the adductor pollicis and orbicularis oculi muscles were measured by acceleromyography. RESULTS: Fifteen males and five females (ASA I and II; 27 +/- 8 yr; 73 +/- 13kg; mean +/- SD) were recruited. Median maximal relaxation was less (P < 0.01) for the diaphragm (89%) than for the adductor pollicis or orbicularis oculi muscles (each 100%). The time to 25% recovery was shorter for the diaphragm than for adductor pollicis or orbicularis oculi (7.5 +/- 3.1 versus 14.1 +/- 3.7 and 15.1 +/- 3.5 min, respectively, P < 0.01). Recovery from 25 to 75% was identical for the diaphragm and adductor pollicis (9.4 +/- 2.9 versus 9.1 +/- 3.5 min), but longer for orbicularis oculi (13.4 +/- 4.2 min, P < 0.01). The median recovery time to TOF0.8 was shorter for the diaphragm (23.9 min) than for the adductor pollicis or orbicularis oculi muscles (31.5 and 28.4 min, respectively; P < 0.05). CONCLUSIONS: As with other non-depolarizing muscle relaxants, the duration of the clinical effect of rapacuronium was shorter for the diaphragm than for skeletal muscle. The recovery index was identical for the diaphragm and adductor pollicis.

Carbon dioxide absorption during extraperitoneal and transperitoneal endoscopic hernioplasty.

UNLABELLED: Transabdominal preperitoneal (TAPP) or total extraperitoneal (TEP) hernioplasty are probably associated with differing degrees of CO(2) absorption which can influence anesthetic management and perioperative morbidity. We studied 20 patients with either TAPP or TEP for perioperative CO(2) absorption (calculated from CO(2) elimination and metabolic CO(2) production) and ventilatory changes required to maintain normocapnia (blood gas analyses). CO(2) absorption reached plateau values in the TAPP group, but increased over time in the TEP group. Median CO(2) absorption during insufflation was 61 mL/min (range 43-78) for TAPP and 114 mL/min (range 75-178) for TEP, with a maximum of 114 mL/min (range 75-178) for TAPP and 258 mL/min (range 112-585) for TEP. Median minute ventilation (V(E)) required for maintaining normocapnia was 9. 5 L/min (range 7.7-11.5) for TAPP and 12.9 L/min (range 9.0-22.6) for TEP (P: < 0.01). Seven patients in the TEP group required over 18 L/min V(E), although no patient in the TAPP group required more than 14 L/min V(E). All patients in the TEP group had significant subcutaneous emphysema resulting in one case of delayed tracheal extubation. We conclude that CO(2) absorption is consistently less with TAPP. IMPLICATIONS: The greater magnitude of carbon dioxide absorption during total extraperitoneal hernioplasty puts an additional load on the lungs and could pose a risk for patients with chronic lung disease who might be unable to eliminate excess carbon dioxide.

[Comparison of sufentanil-propofol-anesthesia with fentanyl-propofol in major abdominal surgery]. / Vergleich einer Sufentanil-Propofol-Anästhesie mit Fentanyl-Propofol bei grossen abdominalchirurgischen Eingriffen.

UNLABELLED: Major abdominal surgery often leads to a marked sympathoadrenal stress response with high concentrations of plasma catecholomines, hypertension, and tachycardia. We compared the effects of sufentanil-propofol with fentanyl-propofol anaesthesia in a controlled, randomised, double-blind study of 18 ASA I-II patients aged 23-64 years undergoing major abdominal surgery. Study parameters were haemodynamics (heart rate [HR], arterial [ABP], central venous, and pulmonary arterial pressures, cardiac index [CI]), arterial catecholamine concentrations, and the median frequency of the electroencephalogram (EEG) power spectrum. METHODS: After premedication with flunitrazepam 1-2 mg, promethazine 25-50 mg, and piritramide 7.5-15 mg, a five-lead electrocardiograph and a Lifescan brain activity monitor were attached and indwelling cannulae were inserted into the radial artery and two forearm veins. A thermodilution catheter was placed in the pulmonary artery via the right internal jugular vein. Anaesthesia was induced with either fentanyl 7 micrograms/kg followed by 5 micrograms/kg.h or sufentanil 1 microgram/kg followed by 0.7 microgram/kg.h up to the end of surgery. Additional boli of the opioids were given according to set criteria, resulting in an average consumption of 9.03 micrograms/kg.h fentanyl or 1.22 micrograms/kg.h sufentanil. Propofol 2 mg/kg was given followed by 6 micrograms/kg.h up to the end of surgery. Relaxation was obtained with pancuronium 0.025-0.05 mg/kg before and after induction, after tracheal intubation, before and after skin incision, after opening of the peritoneum, and at the end of surgery. RESULTS: No significant differences were observed between the two groups with regard to the study parameters. The duration of surgery and blood loss were similar in both groups, as were patient characteristics. After induction 2 patients in each group developed thoracic rigidity, which was reversible after muscle relaxation. HR, ABP, and CI decreased significantly before skin incision; after surgical stimulation the baseline values were again reached. but not exceeded. No patient developed tachycardia (> 100/min) or hypertension (> 15% higher than baseline pressure) for longer than 10 min during the study period until the end of surgery. The plasma concentrations of epinephrine and norepinephrine decreased significantly during anaesthesia, and under maximum surgical stimulation did not increase higher than the physiological baseline concentrations. The EEG median frequencies decreased after induction, and during the entire anaesthetic period the main activity was in the delta and theta frequency bands. CONCLUSIONS: With both regimens, the sympathoadrenal stress response to major abdominal surgery was nearly completely suppressed, resulting in stable haemodynamics during the operations. Sufentanil and fentanyl were equally well suited as analgesic components of total i.v. anaesthesia with propofol.

[The effect of total intravenous anesthesia with S-(+)-ketamine/propofol on hemodynamic, endocrine and metabolic stress reactions in comparison to alfentanil/propofol in laparotomy]. / Der Einfluss einer totalen intravenösen Anästhesie mit S-(+)-Ketamin/Propofol auf hämodynamische, endokrine und metabolische Stressreaktionen im Vergleich zu Alfentanil/Propofol bei Laparotomien.

Total intravenous anaesthesia with ketamine-propofol offers distinct advantages over a TIVA with an opiate, including less cardiovascular and respiratory depression and an altered neuroendocrine and immunological stress response pattern. The effects of the more active stereoisomer S-(+)-ketamine in combination with propofol on the circulatory, endocrine and metabolic responses to abdominal surgery were compared with those of alfentanil-propofol. Twenty-four patients scheduled for elective hysterectomy participated in this study which had the approval of our institution's ethics committee. Anaesthesia was induced with 2 mg/kg S-(+)-ketamine or 0.05 mg/kg alfentanil, followed by 1 mg/kg propofol. Tracheal intubation was facilitated with 0.06 mg/kg vecuronium. Anaesthesia was maintained with 1 mg/kg per h S-(+)-ketamine or 0.0125 mg/kg per h alfentanil and propofol at an initial rate of 15 mg/kg per h which was reduced to 5 mg/kg per h after 30 min. Blood samples for catecholamines, cortisol and metabolites were drawn at predetermined times from before induction to 6 h postoperatively. Adrenaline and noradrenaline concentrations decreased preoperatively in the ketamine group (K) from 55 to 29 pg/ml and 166 to 39 pg/ml, respectively, and then increased to postoperative maxima of 193 or 315 pg/ml. A similar pre and postoperative course was seen in the alfentanil group (A) with slightly lower (P < 0.05) intraoperative concentrations in A. Cortisol concentrations increased in K from 12 micrograms/dl to 34 micrograms/dl intraoperatively and further to a maximum of 42 micrograms/dl postoperatively. The intraoperative increase was attenuated in A and the difference between the groups was significant (P < 0.0001). The initial ketamine bolus and tracheal intubation caused a marked, transient increase of mean arterial blood pressure from the baseline value of 105 mmHg to 120 mmHg with a subsequent decrease to 88 mmHg prior to skin incision and a gradual return to baseline during surgery. TIVA with ketamine-propofol had little effect on the perioperative courses of the endocrine parameters, which behaved as they do under anesthesia with isoflurane-nitrous oxide. Plasma catecholamine concentrations were not elevated in the period between induction of anaesthesia and skin incision.

Effect of low-level PEEP on inspiratory work of breathing in intubated patients, both with healthy lungs and with COPD.

OBJECTIVE: Evaluation of low-level PEEP (5 cm H2O) and the two different CPAP trigger modes in the Bennett 7200a ventilator (demand-valve and flow-by trigger modes) on inspiratory work of breathing (Wi) during the weaning phase. DESIGN: Prospective controlled study. SETTING: The intensive care unit of a university hospital. PATIENTS: Six intubated patients with normal lung function (NL), ventilated because of non-pulmonary trauma or post-operative stay in the ICU, and six patients recovering from acute respiratory failure due to exacerbation of chronic obstructive pulmonary disease (COPD), breathing either FB-CPAP or DV-CPAP with the Bennett 7200a ventilator. INTERVENTIONS: The patients studied were breathing with zero end-expiratory pressure (ZEEP), as well as CPAP of 5 cm H2O (PEEP), with the following respiratory modes: the demand-valve trigger mode, pressure support of 5 cm H2O, and the flow-by trigger mode (base flow of 20 l/min and flow trigger of 2 l/min). Furthermore, Wi during T-piece breathing was evaluated. MEASUREMENTS AND RESULTS: Wi was determined using a modified Campbell's diagram. Total inspiratory work (Wi), work against flow-resistive resistance (W(ires)), work against elastic resistance (Wiel), work imposed by the ventilator system (W(imp)), dynamic intrinsic positive end-expiratory pressure (PEEPidyn), airway pressure decrease during beginning inspiration (P(aw)) and spirometric parameters were measured. In the NL group, only minor, clinically irrelevant changes in the measured variables were detected. In the COPD group, in contrast, PEEP reduced Wi and its components W(ires) and Wiel significantly compared to the corresponding ZEEP settings. This was due mainly to a significant decrease in PEEPidyn when external PEEP was applied. Flow-by imposed less Wi on the COPD patients during PEEP than did demand-valve CPAP. Differences in W(imp) between the flow-by and demand-valve trigger models were significant for both groups. However, in relation to Wi these differences were small. CONCLUSION: We conclude that the application of low-level external PEEP benefits COPD patients because it reduces inspiratory work, mainly by lowering the inspiratory threshold represented by PEEPidyn. Differences between the trigger modes of the ventilator used in this study were small and can be compensated for by the application of a small amount of pressure support.

Total intravenous anaesthesia with sufentanil-midazolam for major abdominal surgery.

Haemodynamic and endocrine stress responses were compared during total intravenous anaesthesia with sufentanil and midazolam or fentanyl and midazolam in patients undergoing elective major abdominal surgery. Twenty-two ASA I and II patients were allocated randomly to receive sufentanil (induction 1.5 micrograms kg-1 plus infusion 1.5 micrograms kg-1 h-1) or fentanyl (induction 10 micrograms kg-1 plus infusion 10 micrograms kg-1 h-1) supplemented with 0.15 microgram kg-1 sufentanil or 1 microgram kg-1 fentanyl as necessary. Midazolam was infused to obtain plasma concentrations of 500-600 ng ml-1. Ventilation was with oxygen-enriched air. The opioid infusion was reduced post-operatively by half and benzodiazepine effects were reversed by titration with flumazenil. Mean arterial pressure, heart rate and cardiac index decreased in both groups after induction (cardiac index: sufentanil 4.94 +/- 0.45 to 2.99 +/- 0.18 litre min-1; fentanyl 4.97 +/- 0.45 to 3.71 +/- 0.36 litre min-1), but all returned to baseline during surgery. With sufentanil; mean arterial pressure was lower throughout the study period, and heart rate was lower intra-operatively. Oxygen uptake decreased in both groups after induction (sufentanil 289 +/- 29 to 184 +/- 21 ml min-1; fentanyl 318 +/- 32 to 216 +/- 32 ml min-1) and remained low with sufentanil until flumazenil was given. Adrenaline concentrations increased in both groups but there was no intergroup difference. The median noradrenaline concentration was lower intra-operatively with sufentanil (0.47 nmol litre-1 (range 0.06-6.77)) than with fentanyl (0.73 nmol litre-1 (0.07-4.58)). Cortisol, glucose and lactate concentrations increased in both groups. Bradycardia occurred in four patients with sufentanil and in three with fentanyl. There were two cases of marked thoracic rigidity with sufentanil and one with fentanyl.

[Total intravenous anesthesia with methohexital-alfentanil or propofol-alfentanil in hypogastric laparotomy. Clinical aspects and the effects of stress reaction]. / Totale intravenöse Anästhesie mit Methohexital-Alfentanil oder Propofol-Alfentanil bei Unterbauchlaparotomien. Klinische Aspekte und Einfluss auf die Stressreaktion.

Total intravenous anaesthesia (TIVA) using a combination of a hypnotic and an analgesic agent is gaining increasing popularity as an alternative to balanced anaesthesia with volatile anaesthetics for abdominal surgery. Among the required characteristics of the drugs used in this technique are a good correlation between dose, plasma concentrations, and effect as well as rapid elimination from the circulation, allowing close control of anaesthetic depth. Two hypnotic drugs with similar pharmacokinetic and pharmacodynamic profiles are propofol and methohexitone, both of which can be employed as a component of a TIVA technique. Two TIVA combinations utilising either of these drugs with alfentanil were tested against isoflurane-nitrous oxide in a balanced regimen. METHODS. Twenty-seven healthy women undergoing hysterectomy for non-malignant diseases participated in the study after having given written consent. They were randomly allocated to receive either isoflurane (Iso), methohexital-alfentanil (M-A), or propofol-alfentanil (P-A). Blood samples for determination of cortisol, prolactin, catecholamines, glucose, lactate, non-esterified fatty acids, and pharmacon concentrations were drawn repeatedly from before induction until 360 min after surgery. Anaesthesia was induced in group Iso with fentanyl 0.1 mg and M 1.5 mg.kg-1 and maintained with Iso-N2O. In the TIVA groups M or P was given in a two-step infusion to load peripheral compartments and then maintain plasma concentrations within the hypnotic range. A was given as a continuous infusion in an identical dose (0.1 mg.kg-1 initial, 0.125 mg.kg-1.h-1 maintenance) in both groups. If signs of insufficient depth of anaesthesia occurred (heart rate or systolic blood pressure > 25% above baseline), then first A (0.5-1 mg), and if that was ineffective, then 50 mg hypnotic was administered. The A infusion was stopped 30 min before the end of surgery, and Iso or the hypnotic was stopped at skin closure. Recovery time was the time until the patients were able to give their birth date after stopping the Iso or hypnotic. RESULTS. The three groups were comparable with regard to age, weight, and duration of surgery. The total doses of M and P were 1,357 +/- 125 mg (mean +/- SEM) and 1,315 +/- 121 mg, respectively, and the total A doses were 20.7 +/- 2.5 mg (M-A) and 23.4 +/- 3.5 (P-A). The peak plasma concentrations were P 10.6 +/- 1.5 micrograms.ml-1 and M 12.4 +/- 2.6 micrograms.ml-1. At the end of surgery the P concentrations were in the projected range while those of M were somewhat lower than expected (P 3.7 +/- 0.4 microgram.ml-1; M 3.5 +/- 0.6 microgram.ml-1). Three patients each in the P-A and M-A groups required supplementary A injections. Five patients in the P-A group required additional bolus injections of the hypnotic as compared to 2 in the M-A group. The median recovery times were Iso 15 min, M-A 50 min, and P-A 25 min (P < 0.05). The incidence of shivering was Iso 3/9, M-A 5/9, and P-A 0/9 (P < 0.05); vomiting occurred with equal frequency in all groups (Iso 33%, M-A 33%, P-A 22%). The patients were somewhat more restless in group M-A. Systolic blood pressure dropped in a similar manner in all groups after induction of anaesthesia (Iso -31%, M-A -37%, P-A -36%) but recovered during surgery. The intraoperative response of cortisol (Iso + 216%, M-A +92%, P-A +43%) and catecholamines (noradrenaline Iso +56%, M-A +30%, P-A -21%) was lower in the TIVA groups, whereas prolactin increased after induction in all groups. Plasma concentrations of glucose, lactate, and fatty acids were lower in the TIVA groups than in the Iso group intraoperatively, but increased to comparable postoperative levels. CONCLUSIONS. Both TIVA regimens are acceptable alternatives to balanced anaesthesia with Iso N2O. (ABSTRACT TRUNCATED)

[TIVA with etomidate-fentanyl versus midazolam-fentanyl. The perioperative stress of coronary surgery overcomes the inhibition of cortisol synthesis caused by etomidate-fentanyl anesthesia]. / TIVA mit Etomidat-Fentanyl versus Midazolam-Fentanyl. Der perioperative Stress der Koronarchirurgie überwindet die Kortisolsynthesehemmung nach einer totalen intravenösen Anästhesie mit Etomidat-Fentanyl.

Etomidate is a hypnotic with only minor effects on haemodynamics. Although its rapid elimination kinetics would suggest its use in total intravenous anaesthesia (TIVA) and sedation, its administration in higher doses or for a prolonged period has been discouraged due to its inhibitory effects on corticosteroid synthesis. Newer evidence that the suppression of cortisol synthesis might not be total requires a re-evaluation of this drug as a component of a TIVA technique. The effects of high-dose etomidate with fentanyl on spontaneous and stimulated corticosteroid levels as a measure of the magnitude and duration of adrenocortical suppression, as well as on plasma concentrations of adrenocorticotropic hormone (ACTH) beta-endorphin, and catecholamines during cardiac surgery were investigated in a prospective, randomised study and compared to those following the administration of midazolam-fentanyl. PATIENTS AND METHODS. Nineteen patients undergoing myocardial revascularisation were assigned to two groups: group 1: etomidate-fentanyl (n = 9) and group 2: midazolam-fentanyl (n = 10). Anaesthesia was induced with fentanyl 0.5 mg and either etomidate 0.3 mg/kg or midazolam 0.2 mg/kg. Relaxation was achieved with pancuronium 0.1 mg/kg. Anaesthesia was maintained during extracorporeal circulation (ECC) with an infusion of etomidate (0.36 mg.kg-1.h-1) or midazolam (0.16 mg.kg-1.h-1) and fentanyl 10 micrograms.kg-1.h-1. Blood samples were drawn before induction, before ECC, and 1, 6, and 20 h after surgery. Cortisol secretion was stimulated with 0.25 mg ACTH1-24 IV at 6 and 20 h postoperatively. RESULTS. The total drug doses were etomidate 87 +/- 3 mg and midazolam 46 +/- 2 mg. Plasma cortisol concentrations decreased in the etomidate group from 20 (10-31) to 10 (6-31) micrograms.dl-1 (median and range) before ECC, but had returned to baseline at 1 h and were significantly increased at 6 h [29 (15-47) micrograms.dl-1] and 20 h [46 (29-62) micrograms.dl-1]. There was no difference between the groups except at 20 h, when cortisol levels were higher in the etomidate group. The stimulated cortisol increase was markedly impaired in this group at both measuring points. ACTH and beta-endorphin were markedly increased in the etomidate group and ACTH concentrations were eight times greater than the corresponding values in the midazolam group after surgery (ACTH 141 vs. 18 pmol.l-1). Plasma catecholamine concentrations increased significantly in both groups. Noradrenaline concentrations were greater in the etomidate group at 6 h after surgery. Two patients in the midazolam group and none in the etomidate group required circulatory support with exogenous catecholamines. DISCUSSION. It is concluded that the stress of cardiac surgery can overcome the block in cortisol synthesis caused by the administration of high-dose etomidate by substantially increasing ACTH secretion. The administration of high-dose etomidate was not associated with cardiovascular instability. The use of etomidate as a component of TIVA can therefore not be ruled out on the grounds of insufficient cortisol secretion.

Long-term effects of two different ventilatory modes on oxygenation in acute lung injury. Comparison of airway pressure release ventilation and volume-controlled inverse ratio ventilation.

A total of 18 patients with acute lung injury (ALI) were sequentially ventilated with two different modes of mechanical ventilation, each applied for a period of 24 h: (1) volume-controlled inverse ratio ventilation (VC-IRV), (2) airway pressure release ventilation (APRV). The individual sequence of both ventilatory modes was randomized. Ventilatory minute volume was adjusted for a PaCO2 of 35 to 45 mm Hg at the beginning of the study during the first ventilatory mode and then kept constant within preset limits. Hemodynamic variables were stable and similar during the 24-h periods of VC-IRV and APRV as well. Despite the lower sedation and spontaneous breathing during APRV, oxygen uptake was similar during both ventilatory modes. During the 24-h period of VC-IRV there was no relevant change of either airway pressures, alveolo-arterial O2 tension difference (AaDO2)/fraction of inspired oxygen (FIO2) or venous admixture. In contrast, peak airway pressures (Pawmax) during APRV were significantly lower (about 30%; p < 0.01), and decreased further within 24 h (p < 0.05). During APRV AaDO2/FIO2 and venous admixture improved significantly with time after more than 8 h (AaDO2/FIO2: 487 versus 414 mm Hg; p < 0.01; venous admixture: 20.6 versus 13.9%; p < 0.01; medians of onset versus end). The improvement was significantly different between both ventilatory modes (p < 0.01). We conclude that this indicates a progressive alveolar recruitment over time during ventilation with APRV.(ABSTRACT TRUNCATED AT 250 WORDS)