Obstructive sleep apnea in Arnold-Chiari malformation treated with acetazolamide

We studied respiratory patterns and transcutaneous gas pressures in two infants with Arnold-Chiari type II malformation referred to us due to repeated episodes of stridor and cyanosis. During both active and quiet sleep, respiration was irregular and absent or inverse thoracic breathing movements and frequent decreases in oxygen saturation to below 80% were observed. When breathing air with 2% CO2 or when given acetazolamide 10 mg/kg, chest wall movements normalized and oxygenation increased to near normal levels. After three months of treatment with acetazolamide 20 mg/kg/24 h no further episodes of hypoventilation or hypoxemia were observed and further treatment could be discontinued. We conclude that stimulation of respiration by CO2 or by acetazolamide appears to recruit chest wall muscles and promote upper airway patency in Arnold-Chiari malformation. A treatment trial with acetazolamide seems justifiable in these infants when respiratory problems are present.

Carbon dioxide prevents pulmonary overcirculation in hypoplastic left heart syndrome

Circulatory and metabolic homeostasis in patients with hypoplastic left heart syndrome is dependent on a delicate balance between systemic and pulmonary blood flow. Hypocarbia can result in a marked decrease in pulmonary vascular resistance accompanied by pulmonary overcirculation, systemic hypotension, metabolic acidosis, and death. This report illustrates that early and precise control of the arterial carbon dioxide tension using inspired carbon dioxide can be effective in preventing or treating instability arising during management of a patient with hypoplastic left heart syndrome.

[CO2-laser treatment of cicatriceal stenosis after Dixon's operation]

A non-tumoral stenosis of the gastrointestinal tract (after rectum resection) was treated successfully with CO2 laser. The case was not suitable for classic surgical resection.

Enhancement of tumor radiosensitivity and reduced hypoxia-dependent binding of a 2-nitroimidazole with normobaric oxygen and carbogen: a therapeutic comparison with skin and kidneys

To evaluate the therapeutic potential of normobaric oxygen and carbogen as hypoxic-cell sensitizers, both radiosensitization in a mouse mammary carcinoma, mouse skin and kidneys, and the reduction in the proportion of hypoxic tumor cells were quantified in mice breathing air, oxygen, or carbogen. Local tumor control, acute skin reactions, reduced renal clearance, and hematocrit were used as assays. X rays as 10 fractions in 5 days were given to skin and tumors and 10F/12 days to kidneys. In the tumor study, the pre-irradiation breathing time was varied from 2 to 20 min. Hypoxic cells, before and during a 10F/5 day schedule, were quantified using a 2-nitroimidazole with a theophylline side chain. Bioreductively reduced metabolites of this probe were localized in hypoxic cells that were then stained using an immunofluorescent technique and analyzed by flow cytometry. The fraction of cells with high fluorescence intensity was 19% in air, 9% in oxygen, and 3% in carbogen-breathing mice. For all three gases, hypoxia-dependent binding was similar in non-irradiated tumors and those treated with four or nine fractions. Both gases significantly enhanced tumor radiosensitivity (ER = 1.3 to 1.6) and carbogen was slightly more effective than oxygen. With carbogen, maximum sensitization was observed with a 5 min pre-irradiation breathing interval. With oxygen, pre-irradiation breathing times of 2-20 min gave similar sensitization. In skin an enhancement ratio of 1.2 was observed, whereas enhancement ratios for both renal endpoints were significantly lower (1.0 to 1.07). Relative to both tissues, there was therefore a substantial therapeutic gain by irradiating CaNT tumors under both gases, especially with carbogen.

Improving the radiation response in a C3H mouse mammary carcinoma by normobaric oxygen or carbogen breathing

The limited therapeutic benefit from nitroimidazoles has renewed the interest in normobaric oxygen as a hypoxic cell radiosensitizer. In this experimental study we have tried to modify the oxygenation of a C3H mammary carcinoma by flushing tumor-bearing mice with oxygen or carbogen for 5 min before and during treatment. The response to these treatments was evaluated by the changes in radiation-induced tumor control (TCD50) and by the changes in tumor hypoxic fraction (HF). Irradiation was given either as a large, single dose or as five equal, daily fractions. High levels of oxygen in the inspired air were found to decrease the TCD50 significantly. The enhancement ratios were in the range of 1.2-1.4 (p less than 0.05) for both single dose and fractionated irradiation, which suggests that hypoxic cells may be important even when reoxygenation is believed to be complete between fractions. The change in TCD50 corresponded to a decrease in the fraction of clonogenic hypoxic cells from 12% to 3-4% (p less than 0.05). Tumor blood flow was not significantly influenced by the gas treatment. This study thus shows that normobaric oxygen/carbogen inhalation may significantly improve the local tumor control by reducing the diffusion related hypoxia within tumors.

Placebo and analgesic nitrous oxide for treatment of the alcohol withdrawal state

We present evidence that analgesic (as distinct from anaesthetic) nitrous oxide is superior to placebo in the treatment of the alcohol withdrawal state. 'Carbogen' as a placebo is as effective as oxygen or medical air. However, placebo alone offers a means of treating the alcohol withdrawal state with a minimum of pharmacological intervention. Analgesic nitrous oxide for those not responding to placebo is a very rapid, effective, and extremely safe treatment which also reduces the use of highly addictive sedative pharmacological agents. This therapy also provides a rapid method of screening those patients requiring intensive monitoring and treatment in hospital from those who might benefit from out-patient therapy alone.

[CO2-induced acral blood flow and the oxygen partial pressure in arterial occlusive disease]

The effect of CO2-containing water on foot skin blood flow (laser-Doppler flux) and transcutaneous oxygen partial pressure (tcpO2) was measured in 16 patients (15 men and 1 woman; mean age 58 [49-71] years) with peripheral arterial occlusive disease (stage II of Fontaine: bilateral occlusions of the superficial femoral arteries). After 30 minutes lying down and 10 minutes sitting up, one lower leg was immersed in fresh water, the other in CO2-containing water (1400 mg CO2/kg H2O), both at 34 degrees C for 20 minutes. On the next day the measurements were repeated changing sides. Skin blood flow of the dorsum of the foot and rhythmic flow oscillations (flux motion) increased threefold in the CO2 water-bath, after a latency period averaging 2 minutes, within 3 minutes from 1.1 to 3.9 relative units (P less than 0.005). Average tcpO2 increased during the bath in CO2 water by 9 mm Hg (P less than 0.005). There was no change in fresh water. The increase in cutaneous blood flow and oxygen partial pressure, which persisted throughout the period in CO2 water, is interpreted as an increase in microcirculation and can explain part of the effectiveness of this largely empirical treatment.

[Comparative study of acetate and bicarbonate hemodialysis in children with chronic uremia]

Comparative studies on 5 children suffering from chronic uremia were performed regarding the efficacy of acetate and bicarbonate hemodialysis. Clinical symptoms, acid-base and blood gas analysis, serum osmolality, blood pressure and EEG were examined. On authors experience the patients tolerated better the bicarbonate dialysis. Laboratory data and blood pressure were found to be closer to the normal values too. The abnormality of EEG made after bicarbonate dialysis were not so expressed than that of acetate dialysis. On the basis of this examinations the authors suggest the bicarbonate hemodialysis in uremic patients with severe cardiovascular and/or neurological complications.

Influence of the 100% w/v perfluorooctyl bromide (PFOB) emulsion dose on tumour radiosensitivity

The radiosensitizing effect of a 100% w/v emulsion of a fluorocarbon, PFOB, which carries 4 times more oxygen than does Fluosol-DA 20% emulsion, was studied on two human tumour xenografts (HRT18 and HT29) and the murine tumour EMT6. This effect was compared with that obtained with carbogen alone. The fluorocrit (amount of fluorocarbon in the blood) and haematocrit remained unchanged from 7 to 65 min post-injection of the emulsion (8 ml/kg). Tumour-bearing mice were pretreated with 100% w/v PFOB emulsion doses ranging from 2 to 15 ml/kg in the presence of carbogen for 30 min prior to and during irradiation. The fluorocrit increased from 1.5% to 9.5% as the dose of 100% w/v PFOB emulsion increased from 2 to 15 ml/kg. The haematocrit remained the same for all the fluorocarbon emulsion doses used. Tumour radiosensitization varied with the fluorocarbon emulsion dose. Clinically relevant doses (2-4 ml/kg) of the 100% w/v PFOB emulsion plus carbogen produced significantly more radiosensitization than carbogen alone, with sensitizing enhancement ratios of 1.4 for EMT6 and 1.7 for HRT18. The radiosensitivity of HRT18 cells was thus very close to that obtained with normally oxygenated cells. For higher doses (8-15 ml/kg) the radiosensitizing effect of 100% w/v PFOB emulsion plus carbogen becomes comparable to that of carbogen alone. These experiments show that clinically useful doses of 100% w/v PFOB plus carbogen produced tumour radiosensitization only at relatively low fluorocrits. Thus the fluorocrit, and hence the fluorocarbon's oxygen-carrying capacity, is not the only factor involved in radiosensitizing tumour cells by oxygen-carrying fluorocarbon emulsions.

Fluosol-DA/carbogen with lonidamine or pentoxifylline as modulators of alkylating agents in the FSaIIC fibrosarcoma

In an effort to increase the efficacy of several antineoplastic alkylating agents (CDDP, L-PAM, CTX, or BCNU), we examined the effect of the modulator Fluosol-DA/carbogen in combination with a second modulator, either lonidamine or pentoxifylline, on the survival of FSaIIC tumor cells and of bone marrow CFU-GM from tumor-bearing C3H mice. Fluosol-DA/carbogen increased the tumor-cell killing activity of each alkylating agent by about 10 times. In contrast, lonidamine alone did not significantly increase the cytocidal activity of any of the alkylating agents tested. However, in combination with Fluosol-DA/carbogen, the use of lonidamine produced about a 100-fold increase in the tumor cell kill achieved with CDDP as compared with CDDP alone. No increase in tumor cell kill over that produced with the single modulator Fluosol-DA/carbogen was seen following the addition of lonidamine to the combination treatment with L-PAM, CTX, or BCNU. Unfortunately, although neither lonidamine nor Fluosol-DA/carbogen alone significantly increased alkylator toxicity to bone marrow CFU-GM, the combination of modulators increased the toxicity of each alkylating agent to bone marrow by about 10 times. Pentoxifylline caused an increase in alkylator activity against the FSaIIC fibrosarcoma only when used with BCNU; this effect was further augmented by the addition of Fluosol-DA/carbogen. The combination of modulators pentoxifylline plus Fluosol-DA/carbogen was more effective than Fluosol-DA/carbogen alone only when the former was used with BCNU, whereas only minimal increases in tumor-cell killing activity were obtained with this modulator combination and CDDP, L-PAM, or CTX. Pentoxifylline increased the bone marrow CFU-GM toxicity of L-PAM by about 10 times. The bone marrow CFU-GM toxicity was further increased by Fluosol-DA/carbogen, as was the toxicity of each of the other alkylating agents. Lonidamine plus Fluosol-DA/carbogen may be useful in increasing the therapeutic efficacy of CDDP, and the combination of pentoxifylline plus Fluosol-DA/carbogen might improve the antitumor activity of BCNU.

[Successful use of C02 laser in septic surgery]

The authors have performed 29 septic operations with a TLS61 CO2 surgical laser with 60 Watt output power. They have gained good experiences with the laser excision of the vascularized, bleeding, inflammated, penetrated by bacteries and infected wounds.

Therapeutic role of carbogen in impaired hearing

The therapeutic role of carbogen was evaluated in subjects with sensorineural hearing loss by administering carbogen, a gas mixture of 95 per cent O2 and 5 per cent CO2, for seven consecutive days (30 min/day) and monitoring puretone audiometry before and after the administration. Significant improvement was observed both in air and bone conduction threshold levels on seventh day, indicating that there was some recoverable portion in the hearing level of these subjects. The improvement in hearing may be due to action of CO2 as an otic vasodilator coupled with supplementation of the O2 requirement of degenerating hair cells. Carbogen thus appears to be useful in persons with impaired hearing, involving the inner ear.

Carbon dioxide laser vaporization of recalcitrant symptomatic plaques of Hailey-Hailey disease and Darier's disease

Carbon dioxide laser vaporization of localized, recalcitrant intertriginous plaques was done in two patients with Hailey-Hailey disease and two patients with Darier's disease. After treatment, only one patient had recurrence in one treatment site. All patients had significant clinical and symptomatic improvement. Destructive treatment must include the follicular infundibulum in Darier's disease, because histologically this was the focus of recurrent disease at one treated site. We suggest carbon dioxide laser vaporization for the treatment of chronic, localized, symptomatic plaques of Hailey-Hailey or Darier's disease, if medical therapy has been ineffective.

Comparison of carbon-dioxide-enriched, oxygen-enriched, and normal air in treatment of acute mountain sickness

Twenty mountaineers with acute mountain sickness (AMS) at an altitude of 4559 m were randomly allocated to treatment with oxygen-enriched (33% oxygen), carbon-dioxide-enriched (3% carbon dioxide), or normal compressed air. Treatment with oxygen significantly improved the arterial partial pressure of oxygen (PaO2), relieved symptoms of AMS, and reduced cerebral blood flow as estimated by transcranial doppler ultrasound examination of the median cerebral artery. The only significant effect of carbon dioxide was increased ventilation resulting in a slight rise in PaO2. Thus, in contrast to previous uncontrolled trials, this study does not support the usefulness of carbon dioxide treatment in AMS.

Radiosensitization of murine tumors by Fluosol-DA 20%

The effect of perfluorochemicals in combination with carbogen breathing on the response of SCK tumors of mice to fractionated irradiation was investigated. The SCK tumors of A/J mice were irradiated twice a day at 3 Gy per fraction (6 Gy per day), with a total dose of 18 Gy over 3 days. When the host animals were treated with an intravenous (iv) injection of 12 ml/kg of Fluosol-DA 20% before the first daily tumor irradiation and carbogen breathing during every X irradiation with Fluosol-DA 20% injection without carbogen breathing. The hypoxic cell fraction, as determined by an in vivo-in vitro cloning assay, decreased significantly, and the intratumor pO2, as determined with microelectrodes, was markedly increased by Fluosol-DA 20% injection and carbogen breathing. It was concluded that oxygenation of hypoxic cells in SCK tumors during the course of fractionated irradiation was improved by the iv injection of Fluosol-DA 20% and carbogen breathing.

[Treatment of sudden deafness: our experience]

The sudden deafness is a common pathology with unilateral affectation and unknown etiology. Nowadays, the treatment is not completely clarified. We compare a urografin-CO2 treatment with CO2 as a single therapy.

The influence of acute venous congestion on the guinea pig cochlea

The effects of sudden occlusion of the vein of the cochlear aqueduct (VCAQ) on the cochlear blood flow, endocochlear potential (EP), endolymphatic and perilymphatic fluid pressures (PE and PP) were studied in the guinea pig. Cochlear blood flow showed a sudden decrease, and EP began to drop within 90 s, ranging from 50 to 70 mV in 5 of 11 animals studied, recovering to normal levels when the animals were placed on a continuous inhalation of carbogen. The PE and PP increased simultaneously (max. PE = 3.4 +/- 1.4 mm Hg; max. PP = 2.5 +/- 1.0 mm Hg) and returned to their initial values after 5 min. The EP was sustained within the normal range, even when there was an apparent decrease in cochlear blood flow (61.4 +/- 8.4%). We believe that variations in EP following VCAQ occlusion were due to anatomical differences in collateral venous communications among the animals studied. Carbogen inhalation produced uniform recovery patterns, indicating that individual collateral vessel responses were eliminated.