Hyperventilation-induced changes of blood cell counts depend on hypocapnia

Voluntary hyperventilation for 20 mm causes haemoconcentration and an increase of white blood cell and thrombocyte numbers. In this study, we investigated whether these changes depend on the changes of blood gases or on the muscle work of breathing. A group of 12 healthy medical students breathed 36 l· min^–1 of air, or air with 5% CO₂ for a period of 20 min. The partial pressure of CO₂ decreased by 21.4 mmHg (2.85 kPa;P < 0.001) with air and by 4.1 mmHg (0.55 kPa;P < 0.005) with CO₂ enriched air. This was accompanied by haemoconcentration of 8.9% with air (P < 0.01) and of 1.6% with CO₂ enriched air (P < 0.05), an increase in the lymphocyte count of 42% with air (P < 0.001) and no change with CO₂ enriched air, and an increase of the platelet number of 8.4% with air (P < 0.01) and no change with CO₂ enriched air. The number of neutrophil granulocytes did not change during the experiments, but 75 min after deep breathing of air, band-formed neutrophils had increased by 82% (P < 0.025), whereas they were unchanged 75 min after the experiment with CO₂ enriched air. Adrenaline and noradrenaline increased by 360% and 151% during the experiment with air, but remained unchanged with CO₂ enriched air. It was concluded that the changes in the white blood cell and platelet counts and of the plasma catecholamine concentrations during and after voluntary hyperventilation for 20 min were consequences of marked hypocapnic alkalosis. It was found that minimal changes of the blood gases, the muscle work of breathing, the chest movements or mechanical influences on the spleen did not contribute to hyperventilation-induced changes of these variables.     

气管插管后行过度通气对后腹腔镜手术患者术中肺功能的影响

目的 探究气管插管后行过度通气对后腹腔镜手术患者肺功能的影响。方法 选择择期行后腹腔镜手术患者44例,采用数字表法随机分为对照组（C组,n=22）和实验组（P组,n=22）。两组均采用间歇正压通气模式,吸入氧浓度为100%,氧流量为2L/min,吸呼比为1∶1.5。C组：气管插管后至气腹前行正常通气：潮气量10ml/kg,频率12次/分,气腹开始后改为潮气量8ml/kg,频率18次/分直至术毕。P组：气管插管后至术毕全程均行过度通气：潮气量8ml/kg,频率18次/分。记录诱导前（T₀）、气腹前（T₁）、气腹10min（T₂）、气腹30min（T₃）、气腹1h（T₄）、气腹结束（T₅）时的气道峰压、呼气末二氧化碳分压,并于上述各时间点分别行动脉血气分析,计算肺动态顺应性（Cdyn）、氧合指数（OI）、呼吸指数（RI）和肺泡-动脉血氧分压差（A-aDO₂）。结果 与C组比较,P组T_1~5时的呼气末二氧化碳分压及动脉血二氧化碳分压降低,T_1~4时气道峰压均降低,T_2~5时动态肺顺应性增高,拔除气管导管时间缩短（P<0.05）。与C组比较,各时间点两组的氧和指数、呼吸指数、肺泡-动脉氧分压差及皮下气肿、术后低氧血症发生率、住院天数比较差异无统计学意义（P>0.05）。结论 气管插管后即刻行过度通气有利于减轻后腹腔镜手术中的二氧化碳蓄积,同时对肺功能有一定的保护作用。     

过度换气综合征的急诊护理措施分析

目的：探究对过度换气综合征患者采取的急诊护理措施以及其临床护理效果。方法选自广东医学院附属东莞市石龙博爱医院2010年1月～2012年1月收治的过度换气综合征患者共100例,随机均分为对照组与观察组（n=50）。对照组患者接受常规的护理措施,观察组患者则接受针对性的急诊护理措施,对比2组患者的临床治疗效果。结果观察组患者接受治疗后2 h内得以缓解的患者有48例,2例患者需留院观察,24 h后出院;对照组患者接受治疗后2 h内得以缓解的患者有42例,5例患者需留院观察,3例患者需住院治疗,相对于对照组患者,观察组患者护理效果更具有优越性,差异有统计学意义（P＜0.05）。结论对过度换气综合征应用急诊护理措施,具有重要的临床意义与价值。     

Effect of hyperventilation on brain tissue oxygen pressure, carbon dioxide pressure, pH value and intracranial pressure during intracranial hypertension in pigs

ＨＤｅｐａｒｔｍｅｎｔｏｆＮｅｕｒｏｓｕｒｇｅｒｙ ,ＣｈａｎｇｚｈｅｎｇＨｏｓｐｉｔａｌ,ＳｅｃｏｎｄＭｉｌｉｔａｒｙＭｅｄｉｃａｌＵｎｉｖｅｒｓｉｔｙ ,Ｓｈａｎｇｈａｉ 2 0 0 0 0 3,Ｃｈｉｎａ (ＢａｏＹＨ ,ＪｉａｎｇＪＹ ,ＺｈｕＣ ,ＬｕＹＣ ,ＣａｉＲＪａｎｄＭａＣＹ)ｙｐｅｒｖｅｎｔｉｌａｔｉｏｎ (ＨＶ )ｈａｓｂｅｅｎｗｉｄｅｌｙｕｓｅｄｔｏｄｅｃｒｅａｓｅｔｈｅｉｎｔｒａｃｒａｎｉａｌｐｒｅｓｓｕｒｅ (ＩＣＰ)ｉｎｔｈｅｐａｔｉｅｎｔｓｗｉｔｈｓｅｖｅｒｅｔｒａｕｍａｔｉｃｂｒａｉｎｉｎｊｕｒｙ…     

Hyperventilation as a model for acute ischaemic hypoxia of the brain: Effects on cortical auditory evoked potentials

Summary Controlled hyperventilation (HV) may be used as an experimental procedure to produce transient ischaemic hypoxia of the brain. The effect of HV on the cortical auditory evoked potential (AEP) components N1 and P2 was studied in ten healthy adult subjects. AEP were recorded before HV, during 3 min of controlled HV, and 1 min and 5 min after the end of HV. The P2 amplitude was significantly reduced by HV and regained its initial value 1 min after the end of HV. The P2 amplitude decrease probably reflects an impairment of synaptic function produced by cerebral hypoxia. Thus, the investigation of cortical AEP components may provide a useful parameter in the study of anti-ischaemic or antihypoxic therapies.     

Hyperventilation-induced ictal fear in nonlesional temporal lobe epilepsy

Hyperventilation is a traditional seizure-provoking procedure used mainly in idiopathic generalized epilepsy and with a relatively limited role in partial epilepsy. Ictal fear is a rare seizure semiology seen in temporal lobe epilepsy. It has been suggested that the amygdala and anterior hippocampus are involved in generating ictal fear. We describe a rare patient with nonlesional temporal epilepsy who, while hyperventilating during an electroencephalography recording, developed complex partial seizures presenting as ictal fear. The particular sensitivity of the anterior hippocampus (probably the amygdala) to hypocapnia might be an important factor contributing to seizures. To avoid misdiagnosing this unusual condition as a pseudo-seizure, a detailed history and seizure semiology, as well as a concurrent electroencephalography recording, are mandatory.     

早期气管切开联合过度通气在重型颅脑损伤中的临床应用价值

目的探讨早期气管切开联合轻~中度过度通气在治疗重型颅脑损伤（sTBI）中的临床应用价值。方法将80例sTBI患者（GCS评分3~8分）随机分为观察组和对照组各40例。观察组患者入院后24 h内行经皮气管切开并呼吸机短时间内维持轻~中度过度通气（HV）,监测呼气末二氧化碳分压（PetCO2）,使PetCO2维持在27~32 mmHg,30 min/次,4次/d（Q6h）,持续7 d。对照组患者入院后持续面罩中流量供氧,出现呼吸衰竭时再行经皮气管切开及机械通气（未进行过度通气）。全部80例患者均予防治感染、脱水降颅压、脑保护、营养支持等对症支持治疗（有手术指征者及时行手术治疗）,连续观察患者伤后第1~7天颅内压（ICP）的变化,所有病例于伤后6个月时根据GOS评估法判断疗效,分为良好、中残、重残、植物生存和死亡。结果观察组经过轻~中度过度通气后能使sTBI患者的ICP迅速下降,与对照组比较差异有统计学意义（P〈0.O1）。观察组与对照组患者半年后预后在良好、中残、重残、植物生存方面比较差异有统计学意义（P〈0.05）,病死率比较差异无统计学意义（P〉0.05）。结论早期气管切开联合轻~中度过度通气在治疗sTBI中有利于降低颅内压,改善重症患者伤后6个月的生存质量。