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PubMed1997

Venous gas embolism--a comparison of carbon dioxide and helium in pigs.

PURPOSE: The use of helium for insufflation during laparoscopic surgery avoids hypercarbia and acidosis associated with absorbed CO2, but the effects of helium gas embolism are unknown. We compared the effects of CO2 with He gas embolism on survival, haemodynamic variables, oxygenation, and ventilation in pigs. METHODS: Anaesthetized juvenile pigs were given progressively larger boluses of either CO2 (n = 5) or He (n = 4) into the right atrium. Measurements of haemodynamic variables, oxygenation, and PETCO2 were made before and after each gas injection. RESULTS: All animals survived injection of 300 ml CO2 while no animal survived more than 120 ml He (P < 0.01). Mean arterial pressure decreased more after 60 ml He (99 +/- 14 to 44 +/- 20 mmHg) than after 60 ml CO2 (110 +/- 12 to 88 +/- 14 mmHg, P < 0.001). Cardiac output did not change at any injection volume. The PETCO2 decreased more after 60 ml He (30 +/- 2 to 3 +/- 6 mmHg) than after 60 ml CO2 (35 +/- 3 to 30 +/- 3 mmHg, P < 0.001). Only the He group showed a decrease in PaO2 (190 +/- 51 to 68 +/- 22 mmHg at 60 ml, P < 0.05). CONCLUSION: Helium gas embolism has a greater deleterious effect than CO2 gas embolism on survival, MAP, PETCO2, and PaO2. These different effects of gas embolism should be recognized when considering the use of helium or other insoluble gases for abdominal laparoscopic insufflation.

Anesthesia↗

PubMed2003

Hyperpolarized 3-helium MR imaging of the lungs: testing the concept of a central production facility.

The aim of this study was to test the feasibility of a central production facility with distribution network for implementation of hyperpolarized 3-helium MRI. The 3-helium was hyperpolarized to 50-65% using a large-scale production facility based at a university in Germany. Using a specially designed transport box, containing a permanent low-field shielded magnet and dedicated iron-free glass cells, the hyperpolarized 3-helium gas was transported via airfreight to a university in the UK. At this location, the gas was used to perform in vivo MR experiments in normal volunteers and patients with chronic obstructive lung diseases. Following initial tests, the transport (road-air-road cargo) was successfully arranged on six occasions (approximately once per month). The duration of transport to imaging averaged 18 h (range 16-20 h), which was due mainly to organizational issues such as working times and flight connections. During the course of the project, polarization at imaging increased from 20% to more than 30%. A total of 4 healthy volunteers and 8 patients with chronic obstructive pulmonary disease were imaged. The feasibility of a central production facility for hyperpolarized 3-helium was demonstrated. This should enable a wider distribution of gas for this novel technology without the need for local start-up costs.

Diagnostic Services↗

PubMed2003

The impact of carbon dioxide and helium insufflation on experimental liver metastases, macrophages, and cell adhesion molecules.

BACKGROUND: Laparoscopic insufflation, proposed to reduce hepatic perfusion, may enhance hepatic tumor spread. It is unknown whether intraabdominal pressure or the gas itself influences hepatic tumor growth. In contrast to carbon dioxide, the alternative gas helium is believed to reduce malignant cell growth. METHODS: For this study, 36 WAG/Rij rats were randomized in two experimental groups. The animals were laparoscopically insufflated with carbon dioxide ( n = 19) or helium gas ( n = 17). Liver metastases were induced by laparoscopic injection of 50,000 CC531 cells into the portal vein. Macroscopic and microscopic analyses of CC531 tumor cell growth, macrophages, and CD44v5, v6 were performed. Data were analyzed by Kruskal-Wallis, Dunn, and Holm tests. RESULTS: No significant differences in macroscopic and microscopic analyses were found between carbon dioxide and helium gas insufflations ( p > 0.05). CONCLUSIONS: Recent studies have shown that insufflation with carbon dioxide may result in increased hepatic tumor growth. The current study comparing carbon dioxide and helium insufflations could show for the first time either oncologic nor immunologic differences in relation to the liver between two different gases. In conclusion, elevated intraabdominal pressure during gas insufflation is responsible for hepatic disadvantages during pneumoperitoneum, not carbon dioxide gas itself.

Animals↗

PubMed2004

Power spectral analysis of heart rate variability during helium pneumoperitoneum: The mechanism of increased cardiac sympathetic activity and its clinical significance.

BACKGROUND: Carbon dioxide pneumoperitoneum (PP) is known to induce increased cardiac sympathetic expression. The role of the insufflated gas involved in this mechanism should be elucidated in an attempt to eliminate its possible serious consequences. METHODS: Twenty-five patients undergoing elective laparoscopic cholecystectomy were prospectively analyzed for cardiac autonomic nervous activity by spectral heart rate variability. In 15 patients, helium was used as CO(2) substitution for abdominal insufflation (study group). Four frequency bands of interest were obtained from the power spectrum of R-R intervals, as well as the ratio between the low and high frequency (LF/HF), using the fast Fourier transformation algorithm to characterize the synergy of both autonomic branches during PP. RESULTS: Significantly increased values of the power spectrum related to the LF and VLF bands (from 130 to 377 msec(2)/Hz and from 145 to 516 msec(2)/Hz, respectively) were inspected during CO(2) PP, as well as increased LF/LH ratio (2.1). Using helium as CO(2) substitution has eliminated the significant changes in the power spectrum that reflect increased cardiac sympathetic activity. CONCLUSIONS: The elimination of sympathetic predominance by helium PP indicates the central role of CO(2) in establishing this phenomena. Considering this information and its other known advantages, helium should be considered for use during prolonged laparoscopic procedures for high-risk patients.

Adult↗

PubMed2005

Microsphere intestinal blood flow analysis during pneumoperitoneum using carbon dioxide and helium.

BACKGROUND: Pneumoperitoneum has been associated with a decreased flow in the superior mesenteric artery and portal venous system. Intestinal blood flow was studied during a 2-h pneumoperitoneum with carbon dioxide (CO2) or helium in a porcine model using colored microspheres. METHODS: For this study, 12 pigs were divided into two groups (6 CO2 and 6 helium). Different colored microspheres were injected directly into the left ventricle before, 40, 80, and 120 min after insufflation with either gas at a pressure of 15 mmHg. Microsphere concentration was measured in the mucosa and muscularis/serosa layers of the jejunum, cecum, and sigmoid colon to calculate blood flow. RESULTS: Intestinal perfusion initially increases with insufflation and returns to near baseline levels during pneumoperitoneum of 2 h. The effect of helium on tissue perfusion is similar to that of carbon dioxide. CONCLUSIONS: Intestinal perfusion does not change significantly during prolonged pneumoperitoneum at a pressure of 15 mmHg with CO2 or helium.

Animals↗

PubMed2001

The impact of conventional and laparoscopic colon resection (CO2 or helium) on intraperitoneal adhesion formation in a rat peritonitis model.

BACKGROUND: Although postoperative intra-abdominal adhesion formation has been shown to be less with laparoscopic procedures than with open surgery, the extent of intraperitoneal adhesion formation after open and laparoscopic colon resection in patients with intra-abdominal infection remains unclear. METHODS: A standardized fecal inoculum was intraperitoneally applied in 72 rats to induce peritonitis. The rats were randomized into four groups. The three experimental groups underwent laparoscopic resection of the cecum with carbon dioxide (n = 20) or helium (n = 20) insufflation at a pressure of 8 mmHg, or conventional open cecum resection (n = 20). In the control group, no further manipulations were performed after induction of the peritonitis (n = 12). Blood samples were taken during the perioperative course to determine the plasma levels of tumor necrosis factor-alpha (TNF-alpha) and interleukin-10 (IL-10). The number of intraperitoneal adhesions and the bacterial species of peritoneal swabs were determined in each animal. RESULTS: The adhesions were increased in all operation groups as compared with the control group. The number of adhesions was significantly greater after conventional resection than after laparoscopic approaches (p < 0.01). The overall adhesion score was significantly lower in the helium group (p < 0.05) than in the two other operation groups. There was no difference between the laparotomy and carbon dioxide groups. Whereas postoperative TNF-alpha plasma levels were decreased, IL-10 levels were significantly greater in the helium group than in the other three groups. CONCLUSIONS: Intraperitoneal infection is reducing the benefit of laparoscopic surgery regarding postoperative adhesions. Although laparoscopic resection showed an advantage in the number of adhesions with both gases, the total adhesion score was lowest in the helium group.

Animals↗

PubMed2001

The impact of laparoscopic biopsy of pancreatic lymph nodes on lipid peroxidation using helium and carbon dioxide in BOP-induced pancreatic cancer in hamsters.

BACKGROUND: Increased lipid peroxidation is believed to stimulate liver metastasis in pancreatic cancer. However, the effect of the laparoscopic biopsy of pancreatic lymph nodes on liver metastasis is still unknown. We hypothesized that the effects of a pneumoperitoneum with carbon dioxide (CO2) increase lipid peroxidation and stimulate liver metastasis. METHODS: Ductal pancreatic adenocarcinoma was induced in Syrian hamsters (n = 30) by weekly subcutaneous injections of N-nitrosobis-2-oxopropylamine (BOP) for 12 weeks. In group 1, a laparotomy and biopsy of pancreatic lymph nodes was performed. Groups 2 and 3 underwent laparoscopic biopsy with either CO2 or helium. In the 5th postoperative week, the hamsters were killed and the incidence of liver metastasis was analyzed histopathologically. We then made determinations of the level of lipid peroxidation (thiobarbituric acid-reactive substances [TBARS])as well as the activity of glutathionperoxidase (GSH-PX) and superoxidismutase (SOD) in pancreatic carcinoma and liver metastases of the animals. RESULTS: The incidence of liver metastasis was higher in the CO2 group (60%) than in the helium (30%) and laparotomy groups (20%) (p < 0.05). The concentration of TBARS was greater in pancreatic carcinoma and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastastic hepatic tissue in all groups. Extrametastatic hepatic concentration of TBARS was higher in the CO2 group (19.4 +/- 0.88 nmol/mg protein) than the laparotomy (10.66 +/- 0.95 nmol/mg protein) and helium groups (10.79 +/- 0.58 nmol/mg protein). GSH-PX and SOD activity was significantly lower in pancreatic carcinoma tissue and intrametastatic hepatic tissue than in extratumorous pancreatic and extrametastatic hepatic tissue. However, in the CO2 group (1.24 +/- 0.48 107 U/mg protein), extrametastatic GSH-PX activity was lower than in the laparotomy (1.73 +/- 0.4 107 U/mg protein) and helium groups (1.63 +/- 0.28 107 U/mg protein). CONCLUSION: After laparoscopic biopsy of pancreatic lymph nodes in the CO2 group, lipid peroxidation was increased and GSH-PX activity was decreased in extrametastatic hepatic tissue compared to the intrametastatic sections. This mechanism may be responsible for the increased liver metastasis in the CO2 group.

Animals↗

PubMed1994

Effects of sublethal irradiation with helium ions (300 MeV/nucleon) on basic hematological parameters of mice.

The aim of the experiment was to obtain new knowledge on the biological effectiveness of high-energy (300 MeV/nucleon) helium ions, which represent a part of the spectrum of cosmic rays. Male (CBA x C57BL)F1 mice, 4 months old, were exposed to a dose of 4 Gy helium ions (exposure rate 0.05 Gy/min). As a comparative standard irradiation the same dose of 4 Gy of 137Cs gamma-rays (exposure rate 0.07 Gy/min) was used. Material sampling was performed 6-8 h, 4 days and 9 days after irradiation for both experimental groups mentioned above. There were 7 animals in each group including the control group of non-irradiated mice. Eight basic hematological parameters of peripheral blood, bone marrow, spleen and thymus were studied. On day 4 after the irradiation with helium ions, the values of leukocyte counts in peripheral blood, bone marrow cellularity and spleen cellularity were reduced to about 10% of the respective control values while the decline after irradiation with gamma-rays amounted to about 50%. These and other results presented reflect a high relative biological effectiveness of 300 MeV/nucleon helium ions.

Animals↗

PubMed1988

Treatment planning study for carcinoma of the esophagus: helium ions versus photons.

Helium ion radiotherapy significantly reduces dose to adjoining critical structures in the treatment of carcinoma of the esophagus when the same treatment plan is compared with megavoltage photon therapy. A five-field 18 MV photon treatment plan, selected to minimize lung dose, is compared with helium ions using the same field configuration. Dose volume histograms show target coverage, as well as dose delivered to critical structures lung, heart, mediastinum, and spinal cord. Although both helium ions and photons deliver approximately the same lung dose for this treatment plan, radiation to the heart and spinal cord from this field arrangement is significantly reduced with the helium ion beam. The concentration of dose at the tumor site, while sparing surrounding normal tissue, is characteristic of charged particle therapy, particularly with light ions, which includes particles with Z from that of protons (Z = 1) through that of neon (Z = 10).

Esophageal Neoplasms↗

PubMed1994

Helium charged particle radiotherapy for meningioma: experience at UCLBL. University of California Lawrence Berkeley Laboratory.

PURPOSE: Evaluate the use of helium charged particle radiotherapy in the treatment of residual or unresectable meningioma adjacent to critical structures. METHODS AND MATERIALS: Twenty-nine patients with meningioma of the skull base or spine were irradiated with helium charged particle radiotherapy at the University of California Lawrence Berkeley Laboratory (UCLBL) during the period 1981-1992. Twenty-six patients were treated for intracranial and three for spinal tumors. Total doses of 53.0-80.4 Gray equivalent (GyE) with a mean of 63 GyE were delivered using the helium ion beam. RESULTS: Ten-year local control and survival rates calculated by the Kaplan-Meier product limit method were 84% and 80% respectively. Doses of 60.0 GyE were delivered with a low rate of complications. The only failures were in massive, recurrent tumors. CONCLUSION: High doses using helium charged particle radiotherapy can be safely and effectively delivered to large residual or unresectable meningioma near radiosensitive structures.

Adult↗

PubMed1981

Effect of high helium and hydrostatic pressure on bacterial mutation and growth.

The mutagenic and toxic effect of high helium and hydrostatic pressure were assessed in an in vitro microbial assay using two histidine-dependent strains of Salmonella typhimurium. TA98 and TA100. Bacteria in the presence or absence of mammalian enzyme system were subjected to either 50 or 100 atmospheres absolute (ATA) helium or 300 ATA hydrostatic pressure. The number of revertant colonies, colony forming units and cell growth rates were measured. There was no mutagenic effect of decrease in number of colony forming units at any of the pressures tested. However, a statistically significant decrease in growth rate of exponentially dividing cells was seen at 300 ATA hydrostatic pressure and 100 ATA helium, but not at 50 ATA helium.

Helium↗

PubMed1993

Measuring lung volumes in advanced asbestosis: comparability of plethysmographic and radiographic versus helium rebreathing and single breath methods.

Total lung capacity was measured in 16 workers with pulmonary asbestosis using four standard methods: body plethysmography, radiographic lung area, helium dilution by multiple breath and by single breath (alveolar volume). All men had irregular opacities of ILO profusion category 2/1 or greater and four had pleural plaques in addition. The radiographic and plethysmographic methods produced virtually identical mean values for TLC of 7.52 l and 7.64 l and for RV of 4.06 l and 4.32 l and all values were larger than those by helium dilution. The closed circuit helium dilution method systematically underestimated TLC with a mean of 5.89 l as did single breath helium dilution with a mean of 6.39 l. These men had a larger mean RV/TLC, measuring 56.9% by body plethysmography and 54.6% by X-ray area than by the rebreathing dilutional method which was 43.8%. Air trapping within a normal TLC which characterizes asbestosis is revealed by radiographic and plethysmographic methods but concealed by gas dilution methods. Use of the latter is at least partly responsible for the impression that asbestosis is a 'restrictive disease'.

Aged↗

PubMed2004

Microdialysis study of striatal dopaminergic dysfunctions induced by 3 MPa of nitrogen- and helium-oxygen breathing mixtures in freely moving rats.

Previous studies have demonstrated opposite effects of high-pressure helium and nitrogen on extracellular dopamine (DA) levels, which may reflect disturbances on the synthesis, release or metabolic mechanisms. Intrastriatal microdialysis was used to measure the precursor (tyrosine), DA and its metabolites (DOPAC, HVA) levels under nitrogen- or helium- at pressure up to 3 MPa. Under 3 MPa of helium-oxygen breathing mixtures, the extracellular concentration of tyrosine is decreased while the extracellular concentration of DA is increased. On the contrary, nitrogen-oxygen breathing mixture at the same pressure increased extracellular tyrosine concentration and decreased DA release. Under both conditions, an increment of the DOPAC and HVA levels could be noted. Our results suggest that changes in DA release and metabolism during high-pressure helium exposure reflect the effect of the pressure per se, whereas the intrinsic effects of narcotic gases, although sensitive to pressure, would be revealed by hyperbaric nitrogen exposure.

3,4-Dihydroxyphenylacetic Acid↗

PubMed1998

Ten-year follow-up of helium ion therapy for uveal melanoma.

PURPOSE: To examine the results of helium ion irradiation in 218 patients with uveal melanoma treated more than 10 years ago. METHOD: A retrospective review was made of 218 patients (218 eyes) treated with helium ion radiation for uveal melanoma between 1978 and 1984. RESULTS: After helium ion irradiation, 208 (95.4%) of 218 eyes had local tumor control. Ten years after irradiation, 46 (22.4%) of 218 eyes had been enucleated; the majority of enucleations (37 of 46) resulted from anterior ocular segment complications. Ten years after radiation, 102 (46.8%) of the 218 patients were dead; 51 had non-melanoma-related deaths and 51 had died of metastatic melanoma. Best-corrected visual acuity after radiation was greater than 20/40 in 21 (23%) of 93 eyes of the patients who were alive and who had retained their eyes 10 or more years after treatment. In patients with tumors less than 6 mm in height and more than 3 mm distant from the nerve or the fovea, 13 (72%) of 18 retained visual acuity greater than 20/40. In contrast, only 11% of the patients with either thicker tumors or those close to the nerve or fovea retained that level of visual acuity. CONCLUSIONS: Helium ion irradiation of uveal melanoma is associated with good local tumor control and reasonable retention of the treated eye 10 years after treatment. In eyes with tumors less than 6 mm in thickness and more than 3 mm distant from the optic nerve and fovea, many retain excellent vision.

Adult↗

PubMed1999

Administration of the glutamate uptake inhibitor L-trans-PDC in the globus pallidus and the substantia nigra, but not in the striatum, attenuates the psychostimulant effect of high helium pressure on locomotor activity in the rat.

High helium pressure of more than 2 MPa produces central neuroexcitatory motor behavior. In rodents, symptoms comprise locomotor and motor activity (LMA), myoclonia, and, at pressure greater than 9-10 MPa, convulsions and tonic-clonic seizures. We studied the behavioral effects of bilateral injection of the glutamate uptake inhibitor L-trans-pyrollidine-2,4-dicarboxylic acid (L-trans-PDC), in either the substantia nigra reticulata (SNr), the globus pallidus (GP), or the striatum on high helium pressure-induced LMA and myoclonia. Injection of L-trans-PDC in the GP and the SNr attenuated LMA, whereas injection in the striatum enhanced it. Alternatively, injection of L-trans-PDC in the SNr increased myoclonia, whereas injection in the GP or the striatum showed no effects on myoclonia. These results confirm that helium pressure-induced LMA and myoclonia have different neural origins. According to current thinking on basal ganglia function and previous data, it is suggested that high helium pressure would lead to a reduction of glutamate transmission in the SNr that could contribute to a reduction in activity of the nigrothalamic GABA pathway and then to the occurrence of LMA. It is further suggested that glutamate and DA transmissions in the striatum could have synergistic, rather than antagonistic, influences on motor activity.

Animals↗

PubMed2004

Increased tumor growth after high pressure pneumoperitoneum with helium and air.

BACKGROUND: Tumor growth appears proportional to the pressure of carbon dioxide insufflation during laparoscopic surgery. Air and helium are alternative insufflation gases. The objective of this study is to assess tumor growth after air and helium insufflation at different pressures. METHOD: Ninety-six WAG rats were allocated to either air or helium. In both arms, rats were randomly exposed to a one hour gasless procedure, or to 4 mm Hg, 10 mm Hg, or 16 mm Hg insufflation. At the start of the procedure, 500,000 CC531 tumor cells were injected intraperitoneally. After three weeks, intraperitoneal tumor growth was assessed. RESULTS: Higher insufflation pressures were associated with greater tumor growth. No difference of tumor growth between air and helium insufflation was found. CONCLUSION: In this experimental model, insufflation pressure appeared to have a greater impact on tumor growth than the type of gas. Further studies are necessary but it seems prudent to recommend employment of lower insufflation pressures in laparoscopic oncologic surgery.

Air↗

PubMed2005

Intravenous versus nebulized ceftazidime in ventilated piglets with and without experimental bronchopneumonia: comparative effects of helium and nitrogen.

BACKGROUND: Lung deposition of intravenous cephalosporins is low. The lung deposition of equivalent doses of ceftazidime administered either intravenously or by ultrasonic nebulization using either nitrogen-oxygen or helium-oxygen as the carrying gas of the aerosol was compared in ventilated piglets with and without experimental bronchopneumonia. METHODS: Five piglets with noninfected lungs and 5 piglets with Pseudomonas aeruginosa experimental bronchopneumonia received 33 mg/kg ceftazidime intravenously. Ten piglets with noninfected lungs and 10 others with experimental P. aeruginosa bronchopneumonia received 50 mg/kg ceftazidime by ultrasonic nebulization. In each group, the ventilator was operated in half of the animals with a 65%/35% helium-oxygen or nitrogen-oxygen mixture. Animals were killed, and multiple lung specimens were sampled for measuring ceftazidime lung tissue concentrations by high-performance liquid chromatography. RESULTS: As compared with intravenous administration, nebulization of ceftazidime significantly increased lung tissue concentrations (17 +/- 13 vs. 383 +/- 84 microg/g in noninfected piglets and 10 +/- 3 vs. 129 +/- 108 microg/g in piglets with experimental bronchopneumonia; P < 0.001). The use of a 65%/35% helium-oxygen mixture induced a 33% additional increase in lung tissue concentrations in noninfected piglets (576 +/- 141 microg/g; P < 0.001) and no significant change in infected piglets (111 +/- 104 microg/g). CONCLUSION: Nebulization of ceftazidime induced a 5- to 30-fold increase in lung tissue concentrations as compared with intravenous administration. Using a helium-oxygen mixture as the carrying gas of the aerosol induced a substantial additional increase in lung deposition in noninfected piglets but not in piglets with experimental bronchopneumonia.

Administration, Inhalation↗

PubMed2003

Song syntax changes in Bengalese finches singing in a helium atmosphere.

Male Bengalese finches rely heavily on hearing to maintain adult songs and deafening a bird changes its song syntax immediately. Eight adult male Bengalese finches were placed in a helium atmosphere, which changes the resonance of the vocal tract. Undirected songs were recorded before, during and after this procedure, and the changes in song structure were analyzed. A helium environment increases the amplitude of higher harmonics, as in other bird species. Furthermore, note-to-note transition patterns that were never recorded when singing in normal air appeared in the songs sung in helium air. Therefore, helium can be used to cause reversible syntactical re-organization of songs in Bengalese finches, which can be used to study the neural mechanisms of auditory feedback.

Animals↗