Subcutaneous tissue oxygen and carbon dioxide tensions during hyperbaric oxygenation: an experimental study in rats.

OBJECTIVE: To investigate the response of subcutaneous tissue oxygen (O2) and carbon dioxide (CO2) tensions to hyperbaric oxygenation. DESIGN: Experimental study. SETTING: University hospital, Finland. SUBJECTS: 10 Wistar rats. INTERVENTION: Subcutaneous tissue PO2 and PCO2 were directly measured with an implanted Silastic tube tonometer and capillary sampling technique while breathing air and exposed to hyperbaric oxygen (HBO) at 2.5 or 2.8 ATA pressure. Hyperbaric exposures were carried out in a large multiplace chamber pressurised with air. MAIN OUTCOME MEASURES: Subcutaneous tissue PO2 and PCO2. RESULTS: The mean subcutaneous PO2 rose from the baseline of 8 kPa (60 mmHg) to 16 kPa (112 mmHg) when rats breathed room air during pressurisation to 2.8 atm. When the rats breathed oxygen at 2.5 ATA the maximal mean tissue PO2 was four times higher than the mean starting value. During the HBO treatment at 2.8 ATA the tissue PO2 rose to a value about five times above baseline. The tissue PCO2 values almost doubled during the exposure to HBO at 2.5 ATA, probably because elimination of carbon dioxide was impaired. CONCLUSION: Measurements of tissue PO2 and PCO2 with an implanted Silastic tonometer and a capillary sampling technique can successfully be adapted to hyperbaric conditions. The method yielded reproducible results and is applicable to clinical use in hyperbaric medicine.     

Effect of hyperbaric oxygen on microvascular anastomosis healing and patency in the rat

Recent evidence has shown that changes in blood viscosity and marked increases in both platelet count and fibrinogen concentration occur after exposure to hyperbaric oxygen (HBO). The purpose of the present study was to address whether repeated HBO therapy would increase either hematocrit or platelet count, and to determine if these changes would influence the patency of the microvascular anastomosis, as well as anastomotic healing. Eighty femoral arteries from 40 rats were divided into four groups (n = 10), and arterial anastomoses were performed on normal arteries in the first two groups, and on crushed arteries in the second two groups. One of the normal artery groups and one of the crushed artery groups received repeated HBO treatments for 5 days. Anastomotic patency rates, platelet count, hematocrit, and breaking strength were recorded. Among the results of this study were that: (1) there was no difference in patency rate following HBO treatment in both the normal and crushed artery groups; (2) platelet count was significantly higher following HBO treatment in the groups with the undamaged arteries; (3) breaking strength was significantly increased following HBO treatment in the groups with the crushed arteries. The authors concluded that HBO therapy may be useful in improving the healing of microvascular anastomoses in vessels that have undergone crush injury. Although HBO treatment results in an increased platelet count, this does not influence anastomotic patency.     

Preferential conditions for and possible mechanisms of induction of ischemic tolerance by repeated hyperbaric oxygenation in gerbil hippocampus.

OBJECTIVE: We reported previously that repeated hyperbaric oxygenation (HBO) as pretreatment induced ischemic tolerance in the gerbil hippocampus. This study was conducted to determine the preferential conditions for induction of ischemic tolerance by HBO and the mechanism of this induction through immunohistochemical analysis of Bcl-2, Bax, and manganese superoxide dismutase expression. METHODS: Five-minute forebrain ischemia was produced in gerbils after pretreatment with 2 atmospheres absolute (ATA) HBO once every other day for one, three, or five sessions, 2 ATA hyperbaric air once every other day for five sessions, or 3 ATA HBO once daily for 10 sessions. Histological examinations were then performed. Two days after pretreatment with 2 ATA HBO once every other day for five sessions or with 3 ATA HBO once daily for 10 sessions, sections were analyzed immunohistochemically. RESULTS: Pretreatment with 2 ATA HBO once every other day for three or five sessions induced ischemic tolerance; however, pretreatment with 2 ATA HBO for one session, 2 ATA hyperbaric air once every other day for five sessions, or 3 ATA HBO once daily for 10 sessions did not. Pretreatment with 2 ATA HBO once every other day for five sessions, but not with 3 ATA HBO once daily for 10 sessions, significantly increased Bcl-2 and manganese superoxide dismutase immunoreactivity in the CA1 sector. CONCLUSION: These results suggest that protection against mitochondrial alterations after ischemia through manganese superoxide dismutase and/or Bcl-2 expression may be related to induction of ischemic tolerance by repeated HBO pretreatment.     

Preconditioning with hyperbaric oxygen and hyperoxia induces tolerance against spinal cord ischemia in rabbits

BACKGROUND: The aim of this study was to determine if the ischemic tolerance could be induced in the spinal cord by pretreatment with hyperbaric oxygen (HBO) and what components of HBO (hyperoxia, hyperbaricity, and combination of these two) were critical in the induction of tolerance against ischemic injury. METHODS: In experiment 1, 21 rabbits were randomly assigned to one of three groups (n = 7 each): animals in the control group received no HBO before spinal cord ischemia; animals in the HBO-1 and HBO-2 groups received HBO (2.5 atmosphere absolute [ATA], 100% O2) pretreatment 1 h/day for 3 and 5 days before ischemia, respectively. In experiment 2, 48 rabbits were randomly assigned to one of four groups (n = 12 each): the control group received no HBO (21% O2, 1 ATA, 1 h/day, 5 days) before spinal cord ischemia; the HB group received 1-h treatment in 21% O2 at 2.5 ATA each day for 5 days; the HO group received 1-h treatment in 100% oxygen at 1 ATA each day for 5 days; and the HBO group received HBO (2.5 ATA, 100% O2) treatment 1 h/day for 5 days. Twenty-four hours after the last treatment, spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min. Forty-eight hours after reperfusion, hind-limb motor function and histopathology of the spinal cord were examined in a blinded fashion. RESULTS: In experiment 1, the neurologic outcome in the HBO-2 group was better than that of the control group (P = 0.004). The number of normal neurons in the anterior spinal cord in the HBO-2 group was more than that of the control group (P = 0.021). In experiment 2, the neurologic and histopathologic outcomes in the HBO group were better than that of the control group (P < 0.01). The histopathologic outcome in the HO group was better than that in the control group (P < 0.05). CONCLUSIONS: Serial exposure to high oxygen tension induced ischemic tolerance in spinal cord of rabbits. Simple hyperbaricity (2.5 ATA, 21% O2) did not induce ischemic tolerance.     

Efficacy of steroids and hyperbaric oxygen on survival of dorsal skin flaps in rats

This study was designed to determine if steroids improved skin flap survival in rats, and if steroids and hyperbaric oxygen (HBO) showed an additive beneficial effect. Cranially based, 3 x 9 cm dorsal skin flaps were raised in 60 adult rats. All animals received either intramuscular methylprednisolone (30 mg/kg) or an equal volume of intramuscular saline solution placebo 24 hours and 1 hour before, and 24 hours and 48 hours after, flap elevation. Treatment for animals receiving HBO was begun within 5 hours after flap elevation. The regimen consisted of two 90-minute treatments of 100% oxygen at 2.4 atm separated by 5-hour intervals or room air per day for 3 consecutive days. The 60 rats were divided equally into four treatment groups, as follows: group A, flap elevation alone (control); group B, flap plus steroids; group C, flap plus HBO; and group D, flap plus steroids plus HBO. Surviving flap length was measured by visual inspection 7 days after flap elevation. The mean surviving flap length for group A was 4.9 cm, for group B it was 6.4 cm, for group C it was 6.7 cm, and for group D it was 6.5 cm. The approximately 30% to 36% improvement in surviving flap length was highly statistically significant (p less than 0.006) when compared with controls. However, no statistically significant difference was found between the three treatment modalities. These findings indicate that in a rat dorsal skin flap model, perioperative steroids improve skin flap viability, and that steroids alone are as efficacious as HBO and as steroids combined with HBO.     

The effect of hyperbaric oxygen on glucose utilization in a freeze-traumatized rat brain

Local cerebral glucose utilization was measured with the autoradiographic 2-deoxyglucose technique in rats injured by a focal parietal cortical freeze lesion then treated with hyperbaric oxygen (HBO). The cold lesion depressed glucose utilization in the contralateral as well as in the ipsilateral hemisphere. The largest decreases were observed in ipsilateral cortical areas. Treatment of lesioned animals with HBO at 2 atm for 90 minutes on each of 4 consecutive days tended to increase the overall cerebral glucose utilization measured 5 days after injury when compared to animals exposed to normobaric air. This improvement reached statistical significance in five of the 21 structures studied: the auditory cortex, medial geniculate body, superior olivary nucleus, and lateral geniculate body ipsilateral to the lesion, and the mammillary body. The data indicate that changes in lesioned rats exposed to HBO are not restricted to the period of time that the animals are in the hyperbaric chamber but are persistent.     

Hyperbaric oxygen therapy for interstitial cystitis resistant to conventional treatments

We treated two cases of interstitial cystitis (IC) that were resistant to some conventional therapies with hyperbaric oxygen (HBO). Both patients underwent 20 sessions of 100% oxygen inhalation (2.0 atmosphere absolute for 60 min/day x 5 days/week for 4 weeks) in a hyperbaric chamber. The period of follow up was 12 months for case 1 and 9 months for case 2. After a course of HBO, the bladder mucosal ulcer (Hunner's ulcer) disappeared, and changes from baseline in pain and urinary frequency was constitutively inhibited. There were no adverse events during the 20 treatment sessions. One woman (case 1) had mild Eustachian tube dysfunction, resulting in a transient hearing impairment. HBO seems to be an option for treatment of IC resistant to conventional therapies.     

Preconditioning with Hyperbaric Oxygen and Hyperoxia Induces Tolerance against Spinal Cord Ischemia in Rabbits

Background: The aim of this study was to determine if the ischemic tolerance could be induced in the spinal cord by pretreatment with hyperbaric oxygen (HBO) and what components of HBO (hyperoxia, hyperbaricity, and combination of these two) were critical in the induction of tolerance against ischemic injury.

Methods: In experiment 1, 21 rabbits were randomly assigned to one of three groups (n = 7 each): animals in the control group received no HBO before spinal cord ischemia; animals in the HBO-1 and HBO-2 groups received HBO (2.5 atmosphere absolute [ATA], 100% O2) pretreatment 1 h/day for 3 and 5 days before ischemia, respectively. In experiment 2, 48 rabbits were randomly assigned to one of four groups (n = 12 each): the control group received no HBO (21% O2, 1 ATA, 1 h/day, 5 days) before spinal cord ischemia; the HB group received 1-h treatment in 21% O2 at 2.5 ATA each day for 5 days; the HO group received 1-h treatment in 100% oxygen at 1 ATA each day for 5 days; and the HBO group received HBO (2.5 ATA, 100% O2) treatment 1 h/day for 5 days. Twenty-four hours after the last treatment, spinal cord ischemia was induced by an infrarenal aorta clamping for 20 min. Forty-eight hours after reperfusion, hind-limb motor function and histopathology of the spinal cord were examined in a blinded fashion.

Results: In experiment 1, the neurologic outcome in the HBO-2 group was better than that of the control group (P = 0.004). The number of normal neurons in the anterior spinal cord in the HBO-2 group was more than that of the control group (P = 0.021). In experiment 2, the neurologic and histopathologic outcomes in the HBO group were better than that of the control group (P < 0.01). The histopathologic outcome in the HO group was better than that in the control group (P < 0.05).     

The effect of hyperbaric oxygen therapy on the survival of random pattern skin flaps in nicotine-treated rats

Previous studies have shown that nicotine increases the risk of necrosis in skin flaps. We investigated the effect of hyperbaric oxygen (HBO(2)) treatment on the survival of random skin flaps in nicotine-treated rats. Thirty-two Sprague-Dawley rats were divided into four groups with eight rats in each group. Group 1 (n=8) was the control, group 2 (n=8) received HBO(2) treatment without being exposed to nicotine, group 3 (n=8) received nicotine and group 4 (n=8) received HBO(2) treatment with exposure to nicotine. The rats in the nicotine-treated groups were prepared by treating them with nicotine for 28 days. At the end of the 28th day, standard McFarlane-type random skin flaps were lifted from the backs of all the rats. In groups 2 and 4, HBO(2) treatment started at the 30th min following the surgery and continued once a day for 7 days. The flap survival rates and histopathological evaluation results related to neovascularisation and granulation tissue formation were significantly better in the HBO(2)-treated groups (groups 2 and 4) than in the groups that did not receive HBO(2) treatment (groups 1 and 3) (p < 0.05). The flap survival rates, neovascularisation and granulation tissue formation were highest in group 2 and lowest in group 3 (p ≤ 0.001). No significant difference was observed between group 4, which received HBO(2) treatment with nicotine exposure, and the control group (group 1) (p > 0.05). In conclusion, our study demonstrates that HBO(2) treatment has a positive effect on flap survival in nicotine-treated rats.     

Hyperbaric oxygenation after portal vein emobilization for regeneration of the predicted remnant liver

BACKGROUND: Liver failure often develops after extensive liver resection. Preoperative portal vein embolization to induce compensatory hypertrophy in the predicted remnant liver decreases clinical complications after hepatectomy. The aim of this study was to examine whether hyperbaric oxygenation (HBO) after portal vein embolization increases compensatory hypertrophy of the predicted liver remnant. We performed portal vein ligation and HBO in rats to investigate whether HBO after portal vein embolization increases compensatory hypertrophy of the predicted remnant liver. METHODS: Rats were divided into four groups that underwent (1) laparotomy only (control group); (2) right portal vein ligation (RPL group); (3) RPL followed by HBO at 2 atm (HBO-2 atm group; 1 h/day, 5 days/week for 2 weeks); or (4) RPL followed by HBO at 3 atm (HBO-3 atm group). Laparotomy was repeated after 2 weeks in each group; serum levels of albumin and hepatocyte growth factor (HGF) were measured, and the ratio of the weights of nonligated to ligated hepatic segments and the percentage of hepatocytes expressing proliferating cell nuclear antigen (PCNA) in ligated hepatic segments were determined. RESULTS: In rats that had received HBO after RPL, serum levels of HGF, weight ratios of nonligated to ligated hepatic segments, and the percentage of PCNA-positive hepatocytes in nonligated liver were significantly higher than those in the control group. Furthermore, rats that had undergone 3-atm HBO after RPL had significantly higher serum levels of HGF and percentages of PCNA-positive hepatocytes in nonligated hepatic segments. CONCLUSIONS: Preoperative HBO after portal vein embolization may be useful for inducing compensatory hypertrophy of the predicted remnant liver.     

Effect of VEGF and CX43 on the promotion of neurological recovery by hyperbaric oxygen treatment in spinal cord–injured rats

Background contextSpinal cord injury (SCI) is a serious health issue that may result in high health care costs, with additional social and psychological burdens. Hyperbaric oxygen (HBO) treatment has been found to be beneficial for neurological recovery; however, the underlying mechanisms are yet to be characterized.PurposeThe aim of this study was to investigate the mechanisms of HBO treatment in SCI by measuring the expression levels of vascular endothelial growth factor (VEGF) and Connexin43 (CX43) in the injured spinal cord tissue.Study design/settingAn experiment animal study of rats undergoing SCI and HBO treatment.MethodsThe spinal cord injury model was established in rats, which were randomly divided into the following four groups: (1) the sham-operated group (SH), (2) the sham-operated and hyperbaric oxygen treatment group (SH+HBO), (3) the spinal cord injury group (SCI), and (4) the spinal cord injury and hyperbaric oxygen treatment group (SCI+HBO). For groups of SH+HBO and SCI+HBO, the animals received 1 hour of HBO at 2.0 ATA in 100% O2 twice per day for 3 days and then daily for the following days consecutively after surgery. After operation, neurological assessments were performed, the spinal cord tissue samples were harvested for histopathological evaluation, Western blot and real-time polymerase chain reaction analysis.ResultsThe Basso-Bettie-Bresnahan scores were significantly improved in the SCI+HBO group compared with the SCI group on the postoperative 7th and 14th days. The histology scores were significantly decreased by HBO treatment compared with that in the SCI group on the postoperative 3rd, 7th, and 14th days. Western blot analysis and real-time polymerase chain reaction revealed that the expression level of vascular endothelial growth factor (VEGF) in the SCI+HBO group was significantly increased compared with the SCI group. The protein expression level of CX43 and its mRNA level in the SCI+HBO group were significantly decreased on the postoperative 3rd and 7th days, whereas its expression was significantly increased by HBO treatment on the postoperative 14th day compared with the SCI group.ConclusionsHBO treatment improved neurological recovery when applied after SCI. The expression level changes of VEGF and CX43 may contribute to the further understanding on the molecular mechanisms of HBO treatment on SCI.     

Beneficial effect of hyperbaric oxygen on island flaps subjected to secondary venous ischemia

The potential for hyperbaric oxygen therapy (HBO) to decrease the untoward effects of a secondary ischemic event was studied in the rat superficial epigastric flap model. The secondary venous ischemic flap was created by cross-clamping the vascular pedicles for 2 h. Twenty-four hours later, the flap was reelevated and the venous pedicle was occluded for 5 h. Thirty-two rats were divided into three groups. In experimental group 1, animals received HBO treatment immediately prior to the initial flap elevation and ischemia at 2 atmosphere pressures for 90 min. In experimental group 2, the rats underwent a similar course except for a second 90-min HBO course immediately prior to the secondary venous occlusion. The rats without HBO therapy were used as controls. The results showed that all control flaps were nonviable at 1 week by clinical inspection and fluorescein injection. Complete flap survival occurred in 20% of group 1 flaps and 30.8% of group 2 flaps. Partial flap survival occurred in the rest of the flaps in these two groups, with mean survival areas of 48% and 55%, respectively. In conclusion, HBO treatments significantly increase the survival of flaps subjected to a secondary ischemia, even if administered before the primary ischemia. Administering HBO prior to secondary venous ischemia was marginal, which may be due to the effect of O(2) given by HBO not lasting longer than 5 h.     

Wnt/β-catenin信号通路在高压氧治疗大鼠神经病理性痛中的作用

目的观察高压氧后处理对大鼠神经病理性痛的治疗作用,探讨Wnt/β-catenin信号通路在其中的作用。方法成年雄性SD大鼠30只,采用随机数字表法,将其分为三组:假手术组(S组)、坐骨神经慢性缩窄手术组(CCI组)和高压氧治疗组(HBO组),每组10只。HBO组于术后第1天开始高压氧治疗,连续7d,1次/天。S组和CCI组单纯放入氧舱100min而不接受治疗。于术前1d、术后1、3、5、7d测定机械缩足反射阈值(MWT)和热缩足反射潜伏期(TWL)。术后7d取材,应用Western blot法测定各组大鼠脊髓Wnt3a、β-catenin分子表达,应用免疫组化法测定各组大鼠脊髓Wnt3a蛋白的表达。结果术后1、3、5、7dCCI、HBO组MWT明显低于,TWL明显短于S组(P0.05)。术后1、3、5、7dHBO组MWT明显高于,TWL明显长于CCI组(P0.05)。术后7dCCI组大鼠脊髓Wnt3a、β-catenin蛋白表达明显高于S组和HBO组(P0.05)。术后7dCCI组大鼠脊髓背角Wnt3a、β-catenin蛋白表达明显高于S组和HBO组(P0.05)。应用免疫组化法检测Wnt3a蛋白的表达情况,与Western blot所检测蛋白表达情况相同。结论高压氧后处理能减轻大鼠神经病理性痛,其作用机制可能通过抑制脊髓Wnt/β-catenin信号通路来实现。     

Hemodynamic and oxygenation profiles in the early period after hyperbaric oxygen therapy: an observational study of intensive-care patients

BACKGROUND: We studied whether hemodynamic and oxygenation profiles are altered in critically ill patients after exposure to hyperbaric oxygen (HBO). METHODS: Ten intensive-care patients (two females, eight males) undergoing HBO treatment after major abdominal surgery, after burn injury and after CO poisoning were included. All subjects were put on mechanical ventilation and received continuous sedation, and had HBO treatment at 2.2 absolute atmospheres for 50 min. DESIGN: Observational prospective study, and repeated measure design. RESULTS: Hemodynamic and oxygen transport patterns were determined before (C0), 1 h (C1) and 2 h (C2) after HBO therapy with continuous cardiac output dual oximetry pulmonary arterial catheter, a central venous and radial arterial line. Data were analyzed with non-parametric repeated measure analysis. Key results are expressed as a percentage of baseline (C0 values correspond to 100%) at C1 and C2 (median values, lower and upper limit of confidence interval): cardiac index [C1: 105% (98-135), C2: 99% (91-117), P = 0.19], systemic (P = 0.62) and pulmonary vascular (P = 0.76) resistance indices were unchanged, but pulmonary venous admixture (Qs/Qt) increased [C1: 173% (112-298), C2: 140% (92-241), P = 0.00002)] and arterial oxygen tension decreased [C1: 76% (67-94), C2: 82% (72-112), P = 0.010]. CONCLUSION: The hemodynamic profile remained unaffected. The increase in Qs/Qt and the decrease in PaO2 may be attributed to the inhalation of HBO, and both are reversible.     

Effect of hyperbaric oxygen therapy on the tubed pedicle flap survival in a rat model

The effect of hyperbaric oxygen therapy (HBO) on survival of the distal skin paddle with early pedicle division was studied in a rat tubed pedicle flap model. In part 1, tubed pedicle skin flaps were created on the backs of 14 rats. The pedicle of each skin flap was divided at intervals of 3, 4, 5, and 7 days, and the survival area of each distal skin paddle was measured 5 days after each pedicle was divided. The results showed that the percentages of survival were 0%, 29.9%, 89.9%, and 100% at 3, 4, 5, and 7 days, respectively. In part 2, the tube flaps were created on the backs of 28 rats. The tubed pedicles were divided 4 days after creation. In the experimental group 1 (n = 9), the rats received HBO treatment at 2 atm of pressure twice daily for 3 consecutive days before pedicle division. In the experimental group 2 (n = 9), the rats received HBO treatment after pedicle division twice daily for 3 consecutive days. In the control group (n = 10), the rats received no HBO treatment. The results showed that the mean survival area of the distal skin paddle at 5 days after pedicle division for the groups treated with HBO before and after pedicle division was 6.31 +/- 2.69 cm2 (69.19%) and 6.12 +/- 1.52 cm2 (71.22%), respectively. These survival rates were of statistical significance as compared with the survival rates in the control group of 2.70 +/- 1.89 cm2 (27.9%). These results demonstrate that the administration of HBO therapy to the animal with a tubed pedicle flap can increase flap survival with early division of the tubed pedicle.     

Ultrastructural and functional characteristics of blast injury-induced neurotrauma

OBJECTIVE: The present study investigates whether whole-body or local (chest) exposure to blast overpressure can induce ultrastructural, biochemical, and cognitive impairments in the brain. METHODS: Male Wistar rats were trained for an active avoidance task for 6 days. On day 6, rats that had acquired the avoidance response were subjected to whole-body blast injury (WBBI), generated by large-scale shock tube (n = 40); or local (chest) blast injury (LBI), induced by blast overpressure focused on the right middle thoracic region and generated by small-scale shock tube (n = 40) while the heads of animals were protected. At the completion of cognitive testing, rats were killed at 3 hours, 24 hours, and 5 days after injury. Ultrastructural changes in the hippocampus were analyzed electron microscopically. Parameters of oxidative stress (malondialdehyde and superoxide anion generation) and antioxidant enzyme defense (superoxide dismutase and glutathione peroxidase activity) were measured in the hippocampus to assess biochemical changes in the brain after blast. RESULTS: Ultrastructural findings in animals subjected to WBBI or LBI demonstrated swellings of neurons, glial reaction, and myelin debris in the hippocampus. All rats revealed significant deficits in performance of the active avoidance task 3 hours after injury, but deficits persisted up to day 5 after injury only in rats subjected to WBBI. Oxidative stress development and altered antioxidant enzyme defense was observed in animals in both groups. Cognitive impairment and biochemical changes in the hippocampus were significantly correlated with blast injury severity in both WBBI and LBI groups. CONCLUSION: These results confirm that exposure to blast overpressure induces ultrastructural and biochemical impairments in the brain hippocampus, with associated development of cognitive deficits.     

高压氧与带血供周围神经移植对成鼠损伤脊髓诱发电位的影响

目的：研究高压氧对带血供周围神经移植修复成鼠损伤脊髓功能恢复的作用。方法：将40只成年Wistar大鼠作成脊髓半切损伤模型,随机分为A、B两组,A组单纯带血供周围神经移植修复脊髓损伤,B组为带血供周围神经移植后给予高压氧治疗。手术后1、2、4、8、10周进行感觉诱发电位（SEP）和运动诱发电位（MEP）检查。结果：SEP和MEP潜峰时的恢复B组优于A组。结论：高压氧与带血供周围神经移植对成鼠损伤脊髓功能恢复有较好的促进作用。     

Hyperbaric oxygenation in the treatment regimen using Ilizarov technique in patients with open fractures

The dynamics of clinico-physiological parameters in complex treatment of patients with open fractures of the extremities using hyperbaric oxygenation was analyzed in 22 patients with severe injuries with different degree of ischemia of the extremity, and 9 patients with scanty injuries of the soft tissues. It was shown that vasospasm was observed in patients with the initially normal microcirculation after a course of HBO treatment. In patients with no or initially low capillary blood flow the microcirculation was enlarged due to vasodilatation of the arterioles. No considerable effects of the course of HBO on the main blood flow was revealed. Recommendations are given on using the HBO therapy in management of patients with severe open fractures and osteosynthesis of the injured segment by the Ilizarov methods.     

Arterial oxygen tension increase 2-3 h after hyperbaric oxygen therapy: a prospective observational study

BACKGROUND: Inhalation of hyperbaric oxygen (HBO) has been reported to decrease arterial oxygen tension (PaO(2)) in the early period after exposure. The current investigation aimed at evaluating whether and to what extent arterial blood gases were affected in mechanically ventilated intensive care patients within 6 h after HBO treatment. METHODS: Arterial blood gases were measured in 11 ventilated subjects [nine males, two females, synchronized intermittent mandatory ventilation (SIMV) mode] undergoing HBO therapy for necrotizing soft tissue infection (seven patients), burn injury (two patients), crush injury (one patient) and major abdominal surgery (one patient). Blood gases were obtained with the patients in the supine position under continuous analgesia and sedation before the hyperbaric session (baseline), during isopression, after decompression, after each transport, and 1, 2, 3 and 6 h after exposure. Heart rates and blood pressures were recorded. Intensive care unit (ICU) ventilator settings remained unchanged. Transport and chamber ventilator settings were adjusted to baseline with maintenance of tidal volumes and positive end-expiratory pressure (PEEP) levels. The hyperbaric protocol consisted of 222.9 kPa (2.2 absolute atmospheres) and a 50-min isopression phase. The paired Wilcoxon's test was used. RESULTS: Major findings (median values, 25%/75% quartiles) as per cent change of baseline: PaO(2) values decreased by 19.7% (7.0/31.7, P < 0.01) after 1 h and were elevated over baseline by 9.3% (1.5/13.7, P < 0.05) after 3 h. SaO(2), alveolar-arterial oxygen tension difference and PaO(2)/FiO(2) ratio behaved concomitantly. Acid-base status and carbon dioxide tension were unaffected. CONCLUSION: Arterial oxygen tension declines transiently after HBO and subsequently improves over baseline in intensive care patients on volume-controlled mechanical ventilation. The effectiveness of other ventilation modes or a standardized recruitment manoeuvre has yet to be evaluated.     

脊髓损伤大鼠脊髓组织的病理形态学观察

目的：研究脊髓损伤（SCI）用高压氧（HBO）处理后脊髓的病理学变化。方法：用SD大鼠复制SCI模型，0．1MPa和0．25MPaHBO处理后，取损伤脊髓作HE染色。结果：正常对照组脊髓结构完整，细胞形态正常，分布均匀，胞膜，胞核正常，组织间隙正常，单纯损伤组示组织出血，疏松水肿，细胞空泡变性，神经纤维溶解，消失；处理后，0．25MPaHBO组及0．25MPaHBO＋激素（L，M）组脊髓恢复最明显，组织水肿，细胞空泡变性减轻，细胞形态恢复，结构排列完整，结论：HBO治疗可明显阻止或减轻脊髓损伤的病理变化，有利于脊髓功能的恢复。