Effects of inhalational anaesthesia with low tidal volume ventilation on end-tidal sevoflurane and carbon dioxide concentrations: prospective randomized study

ObjectiveWe investigated how ventilation with low tidal volumes affects the pharmacokinetics of sevoflurane uptake during the first minutes of inhaled anaesthesia.MethodsForty-eight patients scheduled for lung resection were randomly assigned to three groups. Patients in group 1, 2 and 3 received 3% sevoflurane for 3 min via face mask and controlled ventilation with a tidal volume of 2.2, 8 and 12 ml kg⁻¹, respectively (Phase 1). After tracheal intubation (Phase 2), 3% sevoflurane was supplied for 2 min using a tidal volume of 8 ml kg⁻¹ (Phase 3).ResultsEnd-tidal sevoflurane concentrations were significantly higher in group 1 at the end of phase 1 and lower at the end of phase 2 than in the other groups as follows: median of 2.5%, 2.2% and 2.3% in phase 1 for groups 1, 2 and 3, respectively (P < 0.001); and 1.7%, 2.1% and 2.0% in phase 2, respectively (P < 0.001). End-tidal carbon dioxide values in group 1 were significantly lower at the end of phase 1 and higher at the end of phase 2 than in the other groups as follows: median of 16.5, 31 and 29.5 mmHg in phase 1 for groups 1, 2 and 3, respectively (P < 0.001); and 46.2, 36 and 33.5 mmHg in phase 2, respectively (P < 0.001).ConclusionWhen sevoflurane is administered with tidal volume approximating the airway dead space volume, end-tidal sevoflurane and end-tidal carbon dioxide may not correctly reflect the concentration of these gases in the alveoli, leading to misinterpretation of expired gas data.     

Desflurane and sevoflurane in cardiac surgery: a meta-analysis of randomized clinical trials

OBJECTIVES: The authors performed a meta-analysis to investigate whether the cardioprotective effects of volatile anesthetics translate into decreased morbidity and mortality in patients undergoing cardiac surgery. BACKGROUND: It is commonly believed that the choice of the primary anesthetic agent does not result in different outcomes after cardiac surgery. Recent evidence, however, has indicated that volatile anesthetics improve postischemic recovery at a cellular level, in isolated hearts, in animals, and in humans. METHODS: Four investigators independently searched BioMedCentral and PubMed. Inclusion criteria were random allocation to treatment and comparison of a total intravenous anesthesia regimen versus an anesthesia plan including desflurane or sevoflurane performed on cardiosurgical patients. Exclusion criteria were duplicate publications, nonhuman experimental studies, and no outcome data. The endpoints were the rate of perioperative myocardial infarction and hospital mortality. RESULTS: The search yielded 22 studies, involving 1,922 patients. Volatile anesthetics were associated with significant reductions of myocardial infarctions (24/979 [2.4%] in the volatile anesthetics group v 45/874 [5.1%] in the control arm, odds ratio [OR] = 0.51 [0.32-0.84], p for effect = 0.008, and p for heterogeneity = 0.77) and mortality (4/977 [0.4%] v 14/872 [1.6%], OR = 0.31 [0.12-0.80], p for effect = 0.02, and p for heterogeneity = 0.88). CONCLUSIONS: Desflurane and sevoflurane have cardioprotective effects that result in decreased morbidity and mortality. The present data show for the first time that the choice of an anesthetic regimen based on administration of halogenated anesthetics is associated with a better outcome after cardiac surgery.     

Sufentanil supplementation of sevoflurane during induction of anaesthesia: a randomized study

BACKGROUND AND OBJECTIVE: The use of opioids with sevoflurane for induction of anaesthesia is associated with fewer reactions to laryngoscopy but increases the risk of apnoea. Thus it is important to search for the optimal opioid dose. The aim of this study was to compare two sufentanil doses during induction with sevoflurane in young adults. METHODS: Sixty-three young patients (18-26 yr) undergoing wisdom-tooth extraction were randomly allocated to one of the two sufentanil dose groups: 0.15 microg kg(-1) (n = 33) or 0.30 microg kg(-1) (n = 30). Sufentanil was injected 1 min before sevoflurane inhalation. Sevoflurane was inhaled using the three-breath vital-capacity technique with 8% sevoflurane and 100% oxygen. The anaesthesiologist decided when to intubate the trachea. The length of time for intubation was measured. In addition, any apnoea, patient movement, adequacy of the laryngoscopic view, coughing and haemodynamic responses were recorded. RESULTS: Mean time to intubate the trachea, full laryngoscopy view and open-cord position were similar in both groups. The incidence of apnoea was higher in Group 0.30 (P < 0.05). The incidence of patient movement (P < 0.05) and coughing (P < 0.001) was lower in Group 0.30 than in Group 0.15. Sufentanil 0.30 microg kg(-1) attenuated the change in heart rate more effectively than sufentanil 0.15 microg kg(-1). Mean arterial pressure was similar and stable in both groups during induction of anaesthesia. CONCLUSIONS: In current clinical practice during sevoflurane induction, sufentanil 0.30 microg kg(-1) provided a better quality of induction than sufentanil 0.15 microg kg(-1), without significant cardiovascular depression, although the risk of apnoea is increased.     

Total oxygen uptake with two maximal breathing techniques and the tidal volume breathing technique: a physiologic study of preoxygenation

BACKGROUND: Three common methods for preoxygenation are 3 min of tidal breathing, four deep breaths taken within 30 s (4DB), and eight deep breaths taken within 60 s (8DB). This report compares these three techniques in healthy volunteers. METHODS: Five healthy subjects breathed through a mouthpiece and wore a nose clip; oxygen was delivered at 180 l/min via a low-resistance T-piece. Each subject repeated each of the three oxygenation techniques four times. The end-tidal fraction of oxygen was measured, and the oxygen uptake at the mouth was measured breath by breath. The additional difference between oxygen uptake at the mouth during the period of breathing oxygen (as compared with that during air breathing) was taken to represent the total oxygen sequestrated into body stores. RESULTS: The mean +/- SD maximum end-tidal fraction of oxygen after the 4DB method was 0.83 +/- 0.09, which was significantly less than either after the 3-min method (0.92 +/- 0.01; P < 0.04) or after the 8DB method (0.91 +/- 0.04; P < 0.03). The mean additional oxygen taken up during oxygenation with the 4DB method was 1.67 +/- 0.45 l, which was significantly lower than with the 3-min method (2.23 +/- 0.85 l; P < 0.04) or with the 8DB method (2.53 +/- 0.74 l; P < 0.01). There were no significant differences for these variables between the 3-min and 8DB methods. CONCLUSIONS: For the physiologic measurements that were made, both the 3-min and the 8DB method are superior to the 4DB method. The 3-min and 8DB methods seem to be equally effective.     

Intradialytic blood volume monitoring in ambulatory hemodialysis patients: a randomized trial

Complications related to inadequate volume management are common during hemodialysis. This trial tested the hypothesis that availability of an intradialytic blood volume monitoring (IBVM) device improves fluid removal, reducing morbidity. A six-center, randomized trial with 6 mo of intervention comparing IBVM using Crit-Line versus conventional clinical monitoring was conducted. The average rate of non-access-related hospitalizations was compared across treatment groups using Poisson regression. Mortality analysis used the Kaplan Meier method. A total of 227 patients were randomized to Crit-Line, and 216 were randomized to conventional monitoring. Both groups had similar baseline characteristics. During the study, no differences in weight, BP, or number of dialysis-related complications were observed. There were 120 and 81 non-access-related hospitalizations in the Crit-Line and conventional monitoring groups. The adjusted risk ratio for non-access-related and access-related hospitalization was 1.61 (95% confidence interval 1.15 to 2.25; P = 0.01) and 1.52 (95% confidence interval 1.02 to 2.28; P = 0.04) for the Crit-Line monitoring group. Mortality was 8.7% in the Crit-Line monitoring group and 3.3% in the conventional group (P = 0.021). Standardized mortality ratios comparing the Crit-Line and conventional monitoring groups to the prevalent hemodialysis population were 0.77 (NS) and 0.26 (P < 0.001). Hospitalization rates were 1.51 and 1.03 events/yr in the Crit-Line and standard monitoring groups, compared with 2.01 for the prevalent hemodialysis population. IBVM was associated with higher nonvascular and vascular access-related hospitalizations and mortality compared with conventional monitoring. The atypically low hospitalization and mortality rates for the conventional monitoring group suggest that these findings should be generalized to the US hemodialysis population with caution.     

Changes in circulating blood volume following isoflurane or sevoflurane anesthesia

Changes of circulating blood volume (CB volume) measured by the dual indicator dilution method were observed in 33 chronically instrumented mongrel dogs following either alpha-chloralose-urethane (C group), additive isoflurane (I group) or sevoflurane anesthesia (S group). These anesthetic groups were each divided into two subgroups with regard to respiratory care, namely Cp, Ip and Sp for those with intermittent positive pressure ventilation (six animals per subgroups), and Cs, Is and Ss for those with spontaneous breathing (five animals per subgroups).The CB volume under positive pressure ventilation remained unchanged in the Ip and Sp groups at both 0.5 and 1.0 MAC, and in the Cp group. The CB volume remained essentially unchanged in the Cs and Is groups at both 0.5 or 1.0 MAC, but the plasma volume tended to increase slightly in the Is group at 1.0 MAC.In the Ss group under spontaneous breathing, however, the CB volume increased from 84.4 ± 7.0 to 91.4 ± 7.7 at 0.5 MAC, and to 91.4 ± 10.2ml·kg^–1 at 1.0 MAC (0.01 P 0.05). These increases were caused by an increase in the plasma volume.The above data suggests that a concomitant increase in the venous pressure associated with an increase in the intrathoracic pressure produced by positive pressure ventilation would attenuate changes in the CB volume during sevoflurane anesthesia.(Hamada H, Takaori M, Kimura K, et al.: Changes in circulating Blood volume following isoflurane or sevoflurane anesthesia. J Anesth 7: 316–324, 1993)     

Effect of icodextrin on volume status,blood pressure and echocardiographic parameters: a randomized study

Overhydration is a risk factor for hypertension and left ventricular hypertrophy in peritoneal dialysis patients. Recently, a high prevalence of subclinical overhydration was observed in peritoneal dialysis patients. Aim of the present open-label randomized study was to assess the effect of a icodextrin 7.5% solution on fluid status [extracellular water (ECW) bromide dilution], blood pressure regulation (24-hour ambulatory measurements) and echocardiographic parameters during a study period of 4 months, and to relate the effect to peritoneal membrane characteristics (dialysate/plasma creatinine ratio). Forty peritoneal dialysis patients (22 treated with icodextrin, 18 controls) were randomized to either treatment with icodextrin during the long dwell or standard glucose solutions. Thirty-two patients (19 treated with icodextrin, 13 controls] completed the study. The use of icodextrin resulted in a significant increase in daily ultrafiltration volume (744 +/- 767 mL vs. 1670 +/- 1038 mL; P = 0.012) and a decrease in ECW (17.5 +/- 5.2 L vs. 15.8 +/- 3.8 L; P = 0.035). Also the change in ECW between controls and patients treated with icodextrin was significant (-1.7 +/- 3.3 L vs. +0.9 +/- 2.2 L; P = 0.013). The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but significantly related to the fluid state of the patients (ECW:height) (r = -0.72; P < 0.0001). Left ventricular mass (LVM) decreased significantly in the icodextrin-treated group (241 +/- 53 grams vs. 228 +/- 42 grams; P = 0.03), but not in the control group. In this randomized open-label study, the use of icodextrin resulted in a significant reduction in ECW and LVM. The effect of icodextrin on ECW was not related to peritoneal membrane characteristics, but was related to the initial fluid state of the patient.     

The influence of PEEP and tidal volume on central blood volume

BACKGROUND AND OBJECTIVE: Measurement of central blood volumes (CBV), such as global end-diastolic volume (GEDV) and right ventricular end-diastolic volume (RVEDV) are considered appropriate estimates of intravascular volume status. However, to apply those parameters for preload assessment in mechanically ventilated patients, the influence of tidal volume (TV) and positive endexpiratory airway pressure (PEEP) on those parameters must be known. METHODS: In 13 mechanically ventilated piglets, the effect of low (10 mL kg(-1)) and high (20 mL kg(-1)) TVs on CBV was investigated in absence and presence of PEEP (0 and 15 cm H(2)O). GEDV, RVEDV, right heart (RHEDV) and left heart end-diastolic volume (LHEDV) were measured by thermodilution. Blood flow on the descending thoracic aorta measured with an ultrasonic flow-probe served to determine stroke volume (SV). Measurements were performed during baseline conditions, after volume loading with previously extracted haemodilution blood (20 mL kg(-1)) and following haemorrhage (30 mL kg(-1)). RESULTS: Application of PEEP decreased GEDV and SV significantly (P < 0.05). Augmenting TV did not reduce GEDV systematically, but significantly reduced SV (P < 0.05). Changes in ventilator settings only influenced RVEDV following volume loading (P < 0.05). RHEDV and LHEDV decreased following application of PEEP, but only RHEDV decreased after augmenting TV at baseline and following volume loading. Correlation of SV with parameters of CBV was r = 0.487 (P < 0.01) for GEDV, r = 0.553 (P < 0.01) for RVEDV, r = 0.596 (P < 0.01) for RHEDV and r = 0.303 (P < 0.01) for LHEDV. CONCLUSION: Application of PEEP decreases CBV and SV. Augmenting TV reduces SV but not CBV. There is a moderate correlation between parameters of CBV and cardiac performance.     

Isoflurane increases,but sevoflurane decreases blood concentrations of melatonin in women

The blood concentrations of melatonin are elevated by stress-induced sympathetic nerve excitation and are affected by some anesthetics. Isoflurane has an effect to increase sympathetic nerve activity when compared with sevoflurane. This study was performed to investigate the effects of these two anesthetics on the blood concentrations of melatonin. Female patients were anesthetized with either isoflurane or sevoflurane. We obtained blood samples before and 5min after 5% isoflurane (ISO group) or 7% sevoflurane (SEV group) anesthesia. The blood melatonin concentrations during anesthesia in the ISO group increased significantly, from 65 ± 60 to 170 ± 90pg·ml^–l; mean ± SD (P < 0.05), whereas those in the SEV group decreased, from 60 ± 50 to 30 ± 30pg·ml^–l (P < 0.05). In conclusion, isoflurane increases, but sevoflurane decreases blood melatonin concentrations.     

七氟醚潮气量法麻醉诱导对成年女性患者左心功能的影响

目的探讨七氟醚潮气量麻醉诱导方法对成年女性患者左心功能的影响。方法选择拟全麻下妇科手术患者20例,年龄20~48岁,ASAⅠ或Ⅱ级。患者平静自主呼吸,吸入6%七氟醚,氧流量6L/min,监测呼气末七氟醚浓度达2.0MAC值后,维持2.5min,置入喉罩。使用多普勒技术采集麻醉诱导前(T0)、诱导后置入喉罩前(T1)、置入喉罩30s(T2)和置入喉罩3min(T3)的心脏每搏量(SV)、左室舒张末容积(LVEDV)、射血分数(EF)、HR、心输出量(CO)、组织多普勒二尖瓣环后间隔侧E/A比值(TDI E/A)、二尖瓣环后间隔侧舒张早期心肌组织运动峰速度(Ea)、二尖瓣环后间隔侧舒张晚期心肌组织峰速度(Aa)、二尖瓣环后间隔侧收缩期心肌组织运动峰速度(Sa)、Tei指数及MAP,并记录意识消失和诱导完成时间及不良反应的发生情况。结果与T0时比较,T1~T3时SV、EF、TDI E/A、Tei指数明显增加(P0.05);HR、Sa、Ea、Aa明显减慢(P0.05);LVEDV、CO和MAP变化差异无统计学意义。20例患者诱导及喉罩置入顺利,无喉痉挛等不良反应发生。结论七氟醚潮气量法诱导对成年女性左心功能有一定的抑制作用,但这种抑制作用对循环影响不明显。     

Inhalation induction using sevoflurane in children: the single-breath vital capacity technique compared to the tidal volume technique*

The single-breath vital capacity technique is suitable for inhalation induction of anaesthesia, using sevoflurane in children aged > 5 years. The purpose of this randomised trial was to compare the single breath vital capacity technique with the conventional tidal volume technique. Seventy- three ASA 1 or 2 children were instructed during the pre-operative visit in the vital capacity technique. The main criterion measured was time to loss of the eyelash reflex. Induction was performed using a circle-absorber breathing circuit primed with sevoflurane 7% in 50% nitrous oxide/oxygen with 6 l.min(-1) fresh gas flow. Time required for induction, haemodynamic changes, airway tolerance and side-effects were recorded. The children's opinion on the technique used was scored using a visual analogue scale (0-100) and a Smiley scale (0-10). The time to loss of the eyelash reflex was found to be reduced in the vital capacity group compared to the tidal volume group. The time to central myosis, to achieve bispectral index values 60 and 40, haemodynamic changes, respiratory events and side-effect incidences were similar in both groups. However, we found that the vital capacity technique was preferred by the children to the tidal volume technique.     

Hydro-Jet-assisted laparoscopic cholecystectomy: a prospective randomized clinical study

BACKGROUND: A new dissection technique with high-pressure water stream (Hydro-Jet) has recently been applied for selective dissection during various surgical procedures. The aim of this study was to compare Hydro-Jet with the conventional technique for laparoscopic cholecystectomy. METHODS: Eighty patients were randomized to undergo laparoscopic cholecystectomy with standard (n = 40) or Hydro-Jet-assisted (n = 40) dissection techniques. The rates of intraoperative complications, including blood loss and injury to the adjacent organs, were compared between the groups. The versatility of this technique and the features of surgical dissection were also evaluated and compared. RESULTS: Laparoscopic cholecystectomy was successfully completed in all subjects. The mean operative times were 78 minutes (range, 52-120 minutes) and 81 minutes (range, 45-135 minutes) for Hydro-Jet versus conventional dissection, respectively (P = not significant). Complications included gallbladder perforation in 15% and 30% (P <.1) and liver laceration in 0% and 10% (P <.04) with Hydro-Jet and conventional techniques, respectively. Increased hemorrhage from the gallbladder bed that necessitated fulguration occurred in 12 patients with the conventional technique as compared with none in the Hydro-Jet group (P <.001). Hydro-Jet resulted in a selective dissection of connective tissue preserving blood vessels and the cystic duct. The continuous water flow allowed a clear view for the operator, and the dissection was performed in a relatively bloodless field. The ease of blunt dissection with the bent-tip dissector represents another advantage. CONCLUSION: This study shows that Hydro-Jet dissection represents an excellent alternative to the conventional technique for laparoscopic cholecystectomy. The improved anatomic dissection combined with an almost bloodless operating field as the result of continuous water flow decreased the rate of dissection-related complications.     

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.     

A subanesthetic concentration of sevoflurane increases regional cerebral blood flow and regional cerebral blood volume and decreases regional mean transit time and regional cerebrovascular resistance in volunteers

Inhaled anesthetics exert metabolically mediated effects on cerebral blood vessels both directly and indirectly. We investigated the effects of a 0.4 minimum alveolar subanesthetic concentration of sevoflurane on regional cerebral blood flow (rCBF), regional cerebral blood volume (rCBV), regional cerebrovascular resistance (rCVR), and regional mean transit time (rMTT) in volunteers by means of contrast-enhanced magnetic resonance imaging perfusion measurement. Sevoflurane increased rCBF by 16% to 55% (control, 55. 03 +/- 0.33 to 148.83 +/- 1.9 mL. 100 g(-1). min(-1); sevoflurane, 71.75 +/- 0.36 to 193.26 +/- 2.14 mL. 100 g(-1). min(-1)) and rCBV by 7% to 39% (control, 4.66 +/- 0.03 to 10.04 +/- 0.12 mL/100 g; sevoflurane, 5.04 +/- 0.03 to 13.6 +/- 0.15 mL/100 g); however, sevoflurane decreased rMTT by 7% to 18% (control, 3.75 +/- 0.04 to 5. 39 +/- 0.04 s; sevoflurane, 3.4 +/- 0.03 to 4.44 +/- 0.03 s) and rCVR by 22% to 36% (control, 0.74 +/- 0.01 to 1.9 +/- 0.2 mm Hg/[mL. 100 g(-1). min(-1)]; sevoflurane, 0.54 +/- 0.01 to 1.41 +/- 0.01 mm Hg/[mL. 100 g(-1). min(-1)]). Interhemispheric differences in rCBF, rCBV, and rCVR were markedly reduced after the administration of sevoflurane. These findings are consistent with the known direct vasodilating effect of sevoflurane. The decrease in rMTT further shows that rCBF increases more than does rCBV. Furthermore, we can show that the observed increase in rCBF during inhalation of sevoflurane is not explained by vasodilation alone.