Comparison of oxygenated perfluorocarbon and humidified oxygen for rewarming hypothermic miniswine

This study examines a method to rapidly rewarm the core using total liquid ventilation with warmed, oxygenated perfluorocarbon. Yucatan miniswine were splenectomized and surgically implanted with telemetry devices to transmit electrocardiographic response, arterial pressure, and core temperature. Hypothermia (core temperature = 25.9 +/- 1.3 degrees C) was induced by placing cold-water circulating blankets over the animals. Control animals (N = 7) were rewarmed using warm (37.8 degrees C), humidified oxygen. Experimental animals (N = 6) were rewarmed with oxygenated perfluorocarbon liquid (37.3 degrees C). The time to rewarm was significantly shorter in experimental animals (1.98 +/- 0.5 vs. 8.61 +/- 1.6 hours, p < 0.0001), with almost no afterdrop in the experimental group. Lactate dehydrogenase and aspartate aminotransferase were significantly increased in the control animals compared with the experimental animals. All animals that survived being chilled to 25 degrees C survived rewarming. This method may provide a means of more rapidly rewarming profoundly hypothermic victims while reducing the risks associated with current methods.     

Temperature and metabolic responses to inhalation and bath rewarming protocols

Rewarming of mildly hypothermic subjects was compared using three different techniques that have been suggested for use in field situations. Eight subjects were cooled for up to 1 h, on four occasions, in a filled whole-body water calorimeter controlled at 22 degrees C. Following cooling, rewarming was initiated by one of four procedures: inhalation of warmed and humidified air at 40 degrees C or 45 degrees C, immersion in 40 degrees C water, or spontaneously by shivering. Deep body temperature was recorded simultaneously at three different sites: rectal, esophageal, and auditory canal. Skin temperatures were recorded from four sites: chest, forearm, thigh, and calf. Results showed that rapid external rewarming in 40 degrees C water produced the quickest rate of rewarming and smallest magnitude and duration of afterdrop. Regardless of which rewarming protocol was followed, the esophageal site always showed the smallest afterdrop. Although there were no differences in the rewarming rates calculated for each of the three core temperature sites during inhalation and spontaneous rewarming, both auditory canal and esophageal sites rose significantly quicker than rectal during the rapid rewarming in 40 degrees C water. Inhalation rewarming led to a depressed metabolic rate, compared to spontaneous rewarming, which was not compensated by heat provided through the respiratory tract. It was concluded that for mildly hypothermic subjects, rapid rewarming in 40 degree C water was the most efficient procedure and that esophageal temperature--the closest approximation of aortic blood or cardiac temperature--is the most sensitive to change during rewarming by any procedure.(ABSTRACT TRUNCATED AT 250 WORDS)     

Accidental hypothermia: an experimental study of inhalation rewarming.

Inhalation rewarming of hypothermic humans with heated, humidified oxygen was compared to rewarming by immersion in a hot bath. In 10 subjects cooled to approximately 35 degrees C core temperature, there was no significant difference in the amount of temperature "afterdrop" with the two rewarming procedures. Inhalation rewarming provided rapid commencement of increase in tympanic and esophageal temperatures, indicating effective rewarming of critical core regions, especially heart and brain. This method of core rewarming avoids the physiological hazards associated with the peripheral vasodilation which accompanies external rewarming. Moverover the simplicity of application of this method suggests its greater use in both first-aid and hospital treatment of accidental hypothermia.     

Cranial-neck and inhalation rewarming failed to improve recovery from mild hypothermia

INTRODUCTION: Rewarming from hypothermia in a field setting is a challenge due to the typical lack of significant power or heat source, making the targeted application of available heat critical. The highly vascular area of the head and neck may allow heat to be rapidly transferred to the core via blood circulation. At the same time, the warming of only a small skin surface may minimize the rapid rise in skin temperature proposed to attenuate shivering and endogenous heat production. Therefore, we investigated the efficacy of targeting the head and neck for rewarming from mild hypothermia. METHODS: There were 16 participants (9 men, 24.1 +/- 4.5 yr, 15.5 +/- 3.9% body fat; 6 women, 23.0 +/- 5.4 yr, 20.8 +/- 3.2% body fat) who were cooled in 15 degrees C water until rectal or esophageal temperature reached 35.5 degrees C, whereupon they were removed and provided passive (PASS), cranial-neck (CN), or cranial-neck and inhalation (CNIR) rewarming. Heart rate and skin temperature were also measured. RESULTS: The mean cooling times were PASS=83 min (range: 22-295 min), CN=94 min (range: 28-314 min), CNIR=97 min (range: 22-285 min). No significant differences (p > 0.05) were found for magnitude of after-drop (PASS = 0.33 +/- 0.24 degrees C, CN = 0.31 +/- 0.18 degrees C, CNIR = 0.29 +/- 0.28 degrees C esophageal temperature) and duration of afterdrop (PASS = 15.4 +/- 10.2 min, CN = 13.0 +/- 10.1 min, CNIR = 8.8 +/- 6.9 min). No significant differences (p > 0.05) were found for rewarming rate (PASS = 1.85 +/- 1.33 degrees C x h(-1), CN = 1.45 +/- 1.04 degrees C x h(-1), CNIR = 2.24 +/- 1.51degrees C x h(-1) esophageal temperature). DISCUSSION: In summary, neither cranial-neck nor cranial-neck and inhalation rewarming combined have an advantage in reducing the magnitude and duration of after-drop or increasing the rewarming rate over passive rewarming.     

Observation by MR imaging of in vivo temperature changes induced by radio frequency hyperthermia

Volunteers have undergone radio frequency hyperthermia in a magnetic resonance (MR) imaging system to investigate which of several possible MR parameters would be most convenient and sensitive to use to observe in vivo temperature changes. Measurements were made for T1, T2, and perfusion and diffusion variations, although the number of sequences needed at each temperature meant that the number of data points obtainable was limited. However, in the temperature range studied (around 28-42 degrees C), changes in both T1 and the diffusion coefficient were observed that agreed quite well with those predicted theoretically (respectively around 1.3%/degrees C and 2.4/degrees C).     

海水和脂多糖吸入肺损伤的比较研究

目的 比较海水型急性肺损伤(SW-ALI)和脂多糖(LPS)型急性肺损伤(LPS-ALI)的特点,为SW-ALI的治疗提供依据.方法 将48只Wistar大鼠随机均分为对照组、海水组、LPS组,每组16只,海水组和LPS组分别吸入海水(4ml/kg)和LPS(4me/kg)建立ALI模型,分别于建模前及建模后0.5、1、2、4、8h进行动脉血气分析.并于8h后榆测肺微血管通透性(PMVP)、血管外肺水含量指数(EVLWI)、肺组织髓过氧化物酶(MPO)及丙二醛(MDA)含量、Na'-K'-ATP酶(NKA)活性,并观察肺组织病理学变化.结果 海水组和LPS组在吸入海水和LPS后,动脉血氧分压(PaO2)迅速下降,30min时最低,分别为40.62±5.04、41.35±5.77mmHg.8h后虽然逐渐回升至52.83±6.38、58.35±7.01mmHg,但仍显著低于对照组(99.67±6.95mmHg,P<0.01);吸入海水和LPS后,PMVP分别增高至98.57±16.63、82.32±13.84μg/g,EVLWI分别增高至0.68±0.09、0.52±0.05,MPO分别增高至4.05±0.35、3.97±0.41U/g,MDA分别增高至5.73±0.48、5.95±0.51nmol/mg,NKA活性则分别降至3.35±0.26、3.18±0.22μmol/(mg·h).在2h时点以后,海水组的PaO2显著低于LPS组(P<0.05),PMVP、EVLWI显著高于LPS组(P<0.05),而两组的MDA、MPO含量和NKA活性无显著性差异.海水组肺水肿、肺泡内出血、炎性细胞浸润较LPS组重.结论 与LPS-ALI比较,海水吸入所致的ALI引起的肺水肿更加严重.     

Deep local and regional hyperthermia with annular phased array

33 refractory tumors mainly located in the pelvic cavity after definitive treatment were treated by loco-regional hyperthermia alone (n = 11) or by heat in combination with radiotherapy (n = 22) by annular phased array (APA) manufactured by BSD Corp. Tumors were heated up to more than 42 degrees C in 78% of 347 total heat sessions with induction time 22 +/- 1 (S.D.) minutes during which those of intra-pelvic organs were elevated up to between 41 and 42 degrees C. Tumor response was CR 18%, PR 50% by heat (11.2 +/- 1.5 S.D. fractions) combined with radiotherapy (43.8 +/- 12.5 S.D. Gy) and by heat alone (8.6 +/- 1.3 S.D. fractions) CR 18%, PR 9%. In all heat sessions superficial pain 36%, skin burn (grade 1-2) 12% inside annular array and slight to moderate systemic heat stress 100% were the main adverse reactions we experienced.     

Comparison of four noninvasive rewarming methods for mild hypothermia.

Four noninvasive rewarming techniques for mildly hypothermic subjects were compared. Seven subjects were cooled in a water bath of 15 degrees C for 2 h to an average esophageal temperature (Tes) of 36 degrees C. Thereafter, the subjects were rewarmed by immersion of the body in a water bath of 42 degrees C (Method 1), the body but not the extremities in water of 42 degrees C (Method 2), only the extremities in water of 42 degrees C (Method 3), or spontaneous rewarming in blankets (Method 4). Method 1 showed the highest rewarming rate in Tes (10.1 degrees C/h) and an afterdrop in Tes of 0.18 degrees C. Method 2 showed the same afterdrop, but a lower rewarming rate (7.5 degrees C/h). In Method 3, the heat uptake of the extremities was too low to rewarm the subjects effectively. The afterdrop and rewarming rate were 0.38 degrees C and 0.8 degrees C/h, respectively. Method 4 had the lowest rewarming rate (0.2 degrees C/h), and an afterdrop (0.14 degrees C) which was not significantly lower than that of Method 1 or 2. Therefore, Method 1 is recommended for rewarming mild hypothermic subjects because of its high rewarming rate and small afterdrop.     

Immersion of distal arms and legs in warm water (AVA rewarming) effectively rewarms mildly hypothermic humans

INTRODUCTION: Active rewarming of hypothermic victims for field use, and where transport to medical facilities is impossible, might be the only way to restore deep body temperature. In active rewarming in warm water, there has been a controversy concerning whether arms and legs should be immersed in the water or left out. Further, it has been suggested in the Royal Danish Navy treatment regime, that immersion of hands, forearms, feet, and lower legs alone might accomplish rapid rates of rewarming (AVA rewarming). METHODS: On three occasions, six subjects (one female) were cooled in 8 degrees C water, to an esophageal temperature of 34.3+/-0.8 (+/-SD) degrees C. After cooling the subjects were warmed by shivering heat production alone, or by immersing the distal extremities (hands, forearms, feet and lower legs) in either 42 degrees C or 45 degrees C water. RESULTS: The post cooling afterdrop in esophageal temperature was decreased by both 42 degrees C and 45 degrees C water immersion (0.4+/-0.2 degrees C) compared with the shivering alone procedure (0.6+/-0.4 degrees C; p < 0.05). The subsequent rate of rewarming was significantly greater with 45 degrees C water immersion (9.9+/-3.2 degrees C x h(-1)) than both 42 degrees C water immersion (6.1+/-1.2 degrees C x h(-1)) and shivering alone (3.4+/-1.5 degrees C x h(-1); p < 0.05). CONCLUSION: The extremity rewarming procedure was experienced by the subjects as the most comfortable as the rapid rise in deep body temperature shortened the period of shivering. During the extremity rewarming procedures the rectal temperature lagged considerably behind the esophageal and aural canal (via indwelling thermocouple) temperatures. Thus large gradients may still exist between body compartments even though the heart is warmed.     

Measurement of regional lower limb blood flow in normal humans by inhalation of 133Xe

A non-invasive method of measuring regional calf blood flow after inhalation of 133Xe has been investigated. The mean blood flow at rest was 3.3 ml X min-1 X 100 g tissue-1 by the 133Xe method and 3.5 ml X min-1 X 100 g tissue-1 by plethysmography. There was a significant correlation r = 0.88, P less than 0.001. During exercise the mean blood flow in the anterior tibial compartment increased from 3.4 to 10.9 ml X min-1 X 100 g tissue-1 in ten cases and in the posterior compartment from 3.3 to 7.1 ml X min-1 X 100 g tissue-1 in seven cases as measured by the 133Xe technique. The inhalation method seems to be an accurate, reliable and non-invasive method for measuring tissue blood flow in the human calf at rest and during exercise.     

Measurement of regional lower limb blood flow in normal humans by inhalation of 133Xe

A non-invasive method of measuring regional calf blood flow after inhalation of ¹³³Xe has been investigated. The mean blood flow at rest was 3.3 ml·min^-1·100 g tissue^-1 by the ¹³³Xe method and 3.5 ml·min^-1·100 g tissue^-1 by plethysmography. There was a significant correlation r=0.88, P<0.001. During exercise the mean blood flow in the anterior tibial compartment increased from 3.4 to 10.9 ml·min^-1·100 g tissue^-1 in ten cases and in the posterior compartment from 3.3 to 7.1 ml·min^-1·100 g tissue^-1 in seven cases as measured by the ¹³³Xe technique. The inhalation method seems to be an accurate, reliable and non-invasive method for measuring tissue blood flow in the human calf at rest and during exercise.     

头颅降温对高温环境下人脑局部一致性的影响

目的 探讨高温环境下头颅降温对人脑神经活动的影响及其保护机制.方法 16名被试者分别在常温(25℃)、高温(50℃)、头颅降温(舱温:50℃、降温帽:5℃)3组条件下暴露1 h,并采集静息态功能磁共振成像(rs-fMRI)数据.采用REST2.0软件对3组被试者全脑局部一致性(ReHo)值进行单因素方差分析,进一步提取差异显著脑区的ReHo值利用SPSS18.0进行单因素方差分析,并进行事后检验,明确任意2组各脑区神经活性的差异.结果 3组条件下的差异脑区位于右侧眶回、左侧额中回、双侧杏仁核、左侧颞中回、左侧海马、双侧顶下缘角回、左侧中央前回.与常温组相比,头颅降温组ReHo值增大的脑区有右侧眶回,降低的脑区有左侧中央前回、左侧额中回、左侧角回,未见变化的脑区有双侧杏仁核、左侧颞中回、左侧海马、右侧角回.与高温组比较,头颅降温组ReHo值增大的脑区有左侧颞中回、左侧海马、右侧角回,降低的脑区有双侧杏仁核、左侧角回,未见变化的脑区有右侧眶回、左侧中央前回、左侧额中回.结论 头颅降温组ReHo的特异性变化,表明头颅降温可以部分消除高温对大脑ReHo的影响,且与情绪功能存在密切联系.     

靶控吸入七氟烷与传统吸入七氟烷模式麻醉效果比较

目的比较靶控吸入模式与新鲜气体控制吸入模式两种七氟烷吸入模式下手术患者脑电双频指数（BIS）波动、血流动力学稳定性、辅助药物应用、七氟烷消耗量、苏醒情况与术中知晓等方面的差异。方法选择80例拟行脊柱手术的患者,随机分为靶控吸入组（T组）和新鲜气体控制吸入组（F组）,每组40例。两组麻醉诱导相同,顺序静注咪达唑仑0.05 mg/kg和芬太尼4μg/kg后,吸入8%的七氟烷,然后静注维库溴胺0.1 mg/kg,3 min后气管插管。术中麻醉,T组靶控呼出七氟烷浓度为2.3%,F组持续吸入2.3%七氟烷（氧流量1.5 L/min）,两组舒芬太尼按0.15 ng/ml目标血浆浓度靶控输注（TCI）,按需追加维库溴胺。记录并比较两组患者的脑电双频指数（BIS）值、血压、心率、辅助药物剂量、七氟烷消耗量、苏醒时间、苏醒期躁动和术中知晓等情况。结果两组患者均顺利完成手术,T组在术中和结束时的BIS值高于F组（P〈0.05）,T组术中平均动脉压（MAP）高于F组（P〈0.05）,去氧肾上腺素和七氟烷用量明显低于F组（P〈0.05或P〈0.01）,苏醒时间明显短于F组（P〈0.01）,其余指标两组间无显著性差异。结论七氟烷靶控吸入麻醉模式麻醉深度确实可靠,术中血流动力学稳定,七氟烷消耗量低,术后苏醒迅速完全,值得推广应用。     

Combined treatment of inoperable carcinomas of the uterine cervix with radiotherapy and regional hyperthermia

Aim

The disappointing results for inoperable, advanced tumors of the uterine cervix after conventional radiotherapy alone necessitates improving of radiation therapy. Simultaneous chemotherapy or altered radiation fractionation, such as accelerated regimen, increase acute toxicity and treatment is often difficult to deliver in the planned manner. The purpose of this phase II study was to investigate the toxicity and effectiveness of a combined approach with radiotherapy and regional hyperthermia.

Patients and Methods

From January 1994 to October 1995 18 patients with advanced carcinomas of the uterine cervix were treated in combination with radiotherpay and hyperthermia. The patients were treated with 6 to 20 MV photons delivered by a linear accelerator in a 4-field-box technique to a total dose of 50.4 Gy in 28 fractions. In the first and fourth week 2 regional hyperthermia treatments were each applied with the Sigma-60 applicator from a BSD-2000 unit. After this a boost to the primary tumor was given with high-dose-rate iridium-192 brachytherapy by an afterloading technique with 4×5 Gy at point A to a total of 20 Gy and for the involved parametrium anterioposterior-posterioanterior to 9 Gy in 5 fractions.

Results

The acute toxicity was low and similar to an external radiotherapy alone treatment. No Grade III/IV acute toxicity was found. The median age was 47 years (range 34 to 67 years). In 16 of 18 patients a rapid tumor regression was observed during combined thermo-radiotherapy, which allowed the use of intracavitary high-dose-rate brachytherapy in these cases. Complete and partial remission were observed in 13 and 4 cases, respectively. One paitent die not respond to the treatment. The median follow-up was 24 months (range 17 to 36 months). The local tumor control rate was 48% at 2 years. Median T20, T50 and T90 values were 41.7°C (range 40.3 to 43.2°C), 41.1°C (range 39.2 to 42.5°C) and 39.9°C (range 37.7 to 41.9°C), respectively. Cumulative minutes of T90>40°C (Cum40T90) and cumulative minutes, which were isoeffective to 43°C, were calculated (CEM43T90, CEM43T50, CEM43T20). CEM43T90 was found to be a significant parameter in terms of local tumor control for the 4 hyperthermia treatments (p=0.019).

Conclusion s

This treatment modality has proved to be feasible and well tolerable. The rapid tumor shrinkage in the combined approach of radiotherapy with hyperthermia before beginning brachytherapy seems to be a good prerequisite for improving of the disappointing results in cure of advanced cancer of the uterine cervix.     

Response prediction by FDG-PET after neoadjuvant radiochemotherapy and combined regional hyperthermia of rectal cancer: correlation with endorectal ultrasound and histopathology

Accurate response assessment after neoadjuvant therapy is essential in patients with rectal cancer. The aim of this study was to assess the value of fluorine-18 fluorodeoxyglucose positron emission tomography (FDG-PET) in predicting response of locally advanced rectal cancer to preoperative multimodal treatment. Twenty-two consecutive patients with locally advanced (uT3/4) primary rectal cancer were entered in this prospective pilot study. FDG-PET was performed before and after neoadjuvant radiochemotherapy (RCT) with combined regional hyperthermia (RHT). Treatment consisted of external-beam radiotherapy (45 Gy), chemotherapy (folinic acid and 5-fluorouracil) and regional pelvic hyperthermia followed by curative tumour resection 6–8 weeks later. Semi-quantitative measurements (SUV) of tumour FDG uptake were made before and 2–4 weeks after completion of neoadjuvant treatment. Two patients who did not receive post-therapeutic restaging by FDG-PET were excluded from the analysis. Results were correlated with findings on endorectal ultrasound (EUS, n=17 patients) and histopathology. Histopathological evaluation of the resected tumour revealed complete response in one patient, partial response in 12 and stable disease in seven. SUV reduction in tumours was significantly greater in responders than in non-responders [60% (±15%) vs 30% (±18%), P=0.003, CI=95%). Using a minimum post-therapeutic SUV reduction of 36% to define response, FDG-PET revealed a sensitivity of 100% (EUS: 33%) and a specificity of 86% (EUS: 80%) in response prediction; the corresponding positive and negative predictive values were 93% (EUS: 80%) and 100% (EUS: 33%), respectively. FDG-PET results were statistically significant (P<0.001, CI=95%). FDG-PET has great potential in the assessment of tumour response to neoadjuvant RCT in combination with RHT and is superior to EUS for this purpose.