On octanoic acid-induced hyperventilation — implications for hepatic encephalopathy and Reye's syndrome

Medium chain fatty acid sodium octanoate was infused into rabbits as a 0.2 M solution over 4 h resulting in blood and brain octanoate levels of 200-800 mumol/l. The infused animals developed marked hyperventilation leading to a mild respiratory alkalosis. Additionally, octanoate infusion brought about hyperammonemia and hyperlactate acidemia. Another group of rabbits also infused with octanoate but pretreated with indomethacin (10 mg/kg b.wt.) developed neither hyperventilation nor hyperammonemia. Therefore, the conclusion made was that octanoate causes the above mentioned disorders through stimulation of prostaglandin synthesis and especially the PGE2 synthesis. Patients with hepatic encephalopathy and Reye's syndrome have elevated levels of plasma octanoate. The present study suggests that octanoate might be the cause for both the hyperventilation and hyperammonemia observed in patients with hepatic encephalopathy and Reye's syndrome.     

REPRODUCIBILITY OF HYPERVENTILATION OF COLD DRY AIR IN CHILDREN WITH CYSTIC FIBROSIS

Abstract Wheezing is a significant problem in some patients with cystic fibrosis. Currently available tests are not reliable at determining whether this wheezing is due to co-existent asthma or to the underlying pulmonary disease. The reproducibility of hyperventilation of cold dry air (HVCDA) was studied over eight days in 11 children with cystic fibrosis. A group with mild lung disease were selected to minimize the variability due to underlying pulmonary disease. Fifty-six per cent of subjects had consistent responses to HVCDA. A test of reroducibilit was performed on the respiratory heat exchange, the percentage fall in FEV₁ after HVCDA and the ratio of these two (R). Respiratory heat exchange was found to be highly reproducible with a reproducibility co-efficient of 0.97. The percentage fall in FEV₁ after HVCDA and R were not reproducible over the eight-day period. Hyperventilation of cold dry air did not give reproducible results in children with cystic fibrosis, suggesting that a single test may not be suitable for judging bronchial lability. (Aust NZ J Med 1986; 16: 644–647.)     

Continuous Monitoring of Intracranial Pressure in Reye's Syndrome - 5 Years Experience

Monitoring of intracranial pressure (ICP) and efforts to keep the ICP below the critical level are vital in the treatment of Reye's syndrome. Continuous monitoring of ICP was carried out in 21 cases of Reye's syndrome who were at or beyond stage III at the time of admission to the Veterans General Hospital, between January 1981 and August 1986. Seventeen had ICP ranging from 15mmHg to 67mmHg. Three patients died, 1 in stage V with an ICP of 67mmHg received a craniectomy, and 2 others were in stage IV with ICP's of 66mmHg and 25mmHg, respectively. The fatality rate was 14% (3/21). Among 18 patients, 5 had moderate psychomotor retardation (PMR), 4 had severe PMR and 2 had mild PMR. The remaining 7 patients survived without sequelae. Blood exchange transfusion could further reduce ICP and seemed to improve neurologic outcome. Blood ammonia higher than 400μg% is indicative of a bad prognosis. Hyperventilation was the most rapid and effective means of reducing moderate degrees of increased ICP. During intensive supportive care, we also found that coughing, endotracheal intubation, seizures, asynchronous respiration to an artificial respirator, suction of the airway and any painful stimulation caused further increases in ICP and worsened the situation. Care should be given to avoid these factors.     

Factors affecting respiratory system stability

Periodic breathing (recurrent central apneas) occurs frequently during sleep. Periodic breathing can arise as a result of unstable behavior of the respiratory control system. A mathematical model of the respiratory control system was used to investigate, systematically, the effect of severity of disturbances to respiration and certain system parameters on periodic breathing occurring during sleep. The model consisted of multi-compartment representation of O₂ and CO₂ stores, a peripheral controller sensitive to O₂ and CO₂, and a central controller sensitive to CO₂. The effects of hypoxia and hypercapnia on the upper airway muscles were not considered in the model. Episodes of hyperventilation or asphyxia were used to disturb the control system and explore the boundaries of stable breathing. Circulation time and metabolic rate were also varied. Simulations with the model produced the following findings: The number of central apneas associated with periodic breathing were greater as circulation time increased; controller gain increases also made the number of apneas greater, although periodic breathing occurs with lower controller gains as circulation time increases. At each level of circulation time there was a range of controller gain changes which caused little change in the number of apneas. There were more apneas with hypoxia; also the number of apneas increased with sleep-associated reductions in metabolic rate. The more rapidly resting PCO₂ rose at sleep onset, the greater the likelihood of recurrent apneas. Finally, the more intense the disturbance, the more apneas there were.     

Hyperventilation complaints in music performance anxiety among classical music students

Objective

Despite the importance of respiration and hyperventilation in anxiety disorders, research on breathing disturbances associated with hyperventilation is rare in the field of music performance anxiety (MPA, also known as stage fright). The only comparable study in this area reported a positive correlation between negative feelings of MPA and hyperventilation complaints during performance. The goals of this study were (a) to extend these previous findings to the period before performance, (b) to test whether a positive correlation also exists between hyperventilation complaints and the experience of stage fright as a problem, (c) to investigate instrument-specific symptom reporting, and (d) to confirm gender differences in negative feelings of MPA and hyperventilation complaints reported in other studies.

Methods

We assessed 169 university students of classical music with a questionnaire comprising: the State-Trait Anxiety Inventory for negative feelings of MPA, the Nijmegen Questionnaire for hyperventilation complaints, and a single item for the experience of stage fright as a problem.

Results

We found a significant positive correlation between hyperventilation complaints and negative feelings of MPA before performance and a significant positive correlation between hyperventilation complaints and the experience of stage fright as a problem. Wind musicians/singers reported a significantly higher frequency of respiratory symptoms than other musicians. Furthermore, women scored significantly higher on hyperventilation complaints and negative feelings of MPA.

Conclusion

These results further the findings of previous reports by suggesting that breathing disturbances associated with hyperventilation may play a role in MPA prior to going on stage. Experimental studies are needed to confirm whether hyperventilation complaints associated with negative feelings of MPA manifest themselves at the physiological level.     

PETCO2监测过度通气水平对脑外伤患者脑血流、脑代谢和脑灌注的影响

目的 探讨呼吸末二氧化碳分压(PETCO2)监测下过度通气水平对颅脑外伤患者术中脑血流、脑代谢和脑灌注的影响.方法 选择东营鸿港医院神经外科自2009年1月至2012年6月急诊行脑外伤开颅去骨瓣减压血肿清除术的患者70例,按随机数字表法分为A、B2组,每组35例,A组患者PETCO2控制在20～25 mm Hg之间,动脉血二氧化碳分压(PaCO2)维持在22～25 mm Hg之间,B组患者PETCO2控制在25～30 mm Hg之间,PaCO2维持在30～45 mm Hg之间,比较手术开始去骨瓣前2组患者血气分析结果、平均动脉压、颅内压、脑氧分压、脑灌注压和脑氧供需平衡以及代谢产物神经元特异性稀醇化酶(NSE)、葡萄糖、乳酸的变化.结果 手术开始去骨瓣前A组患者的PaCO2水平、平均动脉压、颅内压、NSE、葡萄糖和乳酸水平显著低于B组,差异有统计学意义(P＜0.05);2组患者脑氧分压和脑灌注压、动脉血氧含量(CaO2)、静脉血氧含量(CjvO2)和脑氧摄取率(CERO2)比较差异无统计学意义(P＞0.05).结论 术中将PETCO2控制在20～25 mm Hg之间,能有效维持患者脑血流灌注和脑氧供需平衡,降低病理性代谢产物水平,值得临床重视.     

Change in the electroencephalogram delta wave in the frontal cranial region of rats with the hyperventilation

Hyperventilation is one way to cause activation on the electroencephalogram (EEG) to diagnose brain disorders. The hyperventilation is also known to affect on the delta power in EEG. This study divided the total delta wave into low, middle, and high bands corresponding to the wave frequency. The power in these three delta wave bands was examined in the frontal cranial region of adult male Sprague-Dawley rats hyperventilated with ventilation (VE) of 360, 540, and 720 ml/min for 5 min. The control group was ventilated normally with a volume of 160 ml/min. The results show that the relative power of the low delta band in the rats hyperventilated at 360 ml/min VE was significantly increased compared with powers of pre-hyperventilation (p<0.05). The relative power of the middle delta band was not significantly affected by hyperventilation at any VE, and in the high delta band, all of the relative powers were decreased significantly in all hyperventilated rats compared with powers of pre-hyperventilation (p<0.05). We concluded that hyperventilation affects the frontal cranial region, by increasing the low delta band and decreasing the high delta band.     

Effects of diabetic ketoacidosis in the respiratory system

Diabetes affects approximately 30 million persons in the United States. Diabetes ketoacidosis is one of the most serious and acute complications of diabetes. At the time of presentation and during treatment of diabetic ketoacidosis(DKA), several metabolic and electrolyte derangements can ultimately result in respiratory compromise. Most commonly, hypokalemia, hypomagnesemia and hypophosphatemia can eventually lead to respiratory muscles failure.Furthermore, tachypnea, hyperpnea and more severely, Kussmaul breathing pattern can develop. Also, hydrostatic and non-hydrostatic pulmonary edema can occur secondary to volume shifts into the extracellular space and secondary to increased permeability of the pulmonary capillaries. The presence of respiratory failure in patients with DKA is associated with higher morbidity and mortality. Being familiar with the causes of respiratory compromise in DKA, and how to treat them, may represent better outcomes for patients with DKA.     

Central lactic acidosis,hyperventilation, and respiratory alkalosis: leading clinical features in a 3-year-old boy with malignant meningeal melanoma

Meningeal tumors are extremely rare in children and are diagnostically as well as therapeutically challenging. Among the least common types of malignancies in childhood is malignant melanoma, counting for less than 1% of pediatric tumors. Due to the rarity and the wide spectrum of appearance, initial clinical features may be misleading. A 3-year-old boy was referred to our hospital with symptoms of hyperventilation, dyspnoea, tachycardia, respiratory alkalosis, inarticulate speech, and fatigue. Measurement of pH in cerebrospinal fluid (CSF) yielded central lactic acidosis despite alkalosis in peripheral blood. Diagnostic imaging procedures as well as histology and immunohistochemistry revealed the diagnosis of a malignant meningeal melanoma. We hypothesize that central lactate production of the tumor nests might have induced central acidification, thus inducing hyperventilation by stimulation of central chemoreceptors. This case is a model example of the key role of central pH as an inducer/suppressor of ventilation in humans and illustrates the critical importance of central pH for regulating both ventilation and acid-base homeostasis. Thus, pH of CSF should be measured whenever a malignant brain tumor is suspected. Blüher and Schulz both contributed equally to the study.