脑血管反应性检测方法的临床评价

目的对二氧化碳吸入、屏气及过度换气等3种不同的脑血管反应性检测方法进行比较,拟为临床应用探索一种有效且简便的方法。方法70例健康体格检查者通过经颅多普勒(TCD)超声技术常规检测颅底及颈部各动脉,然后分别进行二氧化碳吸入试验、过度换气试验和屏气试验,记录试验前后双侧大脑中动脉血流速度变化数据和趋势,检测脑血管反应性。结果吸入二氧化碳后,大脑中动脉平均血流速度明显加快,增加率为(44.86±10.18)%;过度换气时,平均血流速度明显减慢,于过度换气20～30s后降至平台期,平均下降率为(33.63±8.62)%,直至过度通气结束血流速度无明显变化。70例受试者平均屏气时间为(41.66±9.51)s,其中男性屏气时间(42.05±9.23)s,女性(40.63±10.47)s,男女之间差异无统计学意义(P>0.05);屏气后大脑中动脉平均血流速度明显加快,增加率为(46.53±11.83)%;平均屏气指数为1.16±0.37;屏气后血流速度增加率和屏气指数之间呈高度正相关(r=0.865,P<0.01);当屏气时间>30s时,无论采用屏气后血流速度增加率或屏气指数作为分析指标,均可准确地反映脑血管反应性变化。对二氧化碳吸入试验、过度换气试验及屏气试验3种不同方法进行比较显示,过度换气试验与二氧化碳吸入试验、屏气试验间差异有统计学意义(P<0.01);而二氧化碳吸入试验与屏气试验之间差异无统计学意义(P>0.05)。结论二氧化碳吸入试验、屏气试验和过度换气试验均可有效地评价脑血管反应性,其中以屏气试验评价脑血管反应性更为简便。     

The ventilatory threshold gives maximal lactate steady state

Summary The purpose of this study was to examine whether the ventilatory threshold (Th _v) would give the maximal lactate steady state ([1a]_{ss, max}), which was defined as the highest work rate (W) attained by a subject without a progressive increase in blood lactate concentration [1a]_b at constant intensity exercise. Firstly, 8 healthy men repeated ramp-work tests (20 W·min^–1) on an electrically braked cycle ergometer on different days. During the tests, alveolar gas exchange was measured breath-by-breath, and theW atTh _v (W _{Th v}) was determined. The results of two-way ANOVA showed that the coefficient of variation of a singleW _{Th v} determination was 2.6%. Secondly, 13 men performed 30-min exercise atW _{Th v} (Th _v trial) and at 4.9% aboveW _{Th v} (Th _v + trial), which corresponded to the 95% confidence interval of the single determination. The [1a]_b was measured at 15 and 30 min from the onset of exercise. The [1a]_b at 15 min (3.15 mmol·1^–1, SEM 0.14) and at 30 min (2.95 mmol·1^–1, SEM 0.18) were not significantly different inTh _v trial. However, the [1a]_b ofTh _v+ trial significantly increased (P<0.05) from 15 min (3.62 mmol·1^–1, SEM 0.36) to 30 min (3.91 mmol·1^–1, SEM 0.40). These results indicate thatTh _v gives the [1a]_ss,max, at which one can perform sustained exercise without continuous [1a]_b accumulation.     

Beta-adrenergic drugs do not affect phrenic nerve afterdischarge

Summary In anesthetized cats, a carotid sinus nerve was stimulated electrically. After this stimulation the time course of the afterdischarge in the phrenic nerve activity was studied in the control situation, during infusion of isoprenalin and after administration of metoprolol. The time courses were identical in all situations.It is concluded that in spite of the fact that the beta-adrenergic drugs change the steady state phrenic nerve activity, the afterdischarge is unchanged and therefore probably mediated by a separate mechanism. A comparison is made with analogous findings in patients with a hyperventilation syndrome.     

不同通气方式对机械通气引起急性肺损伤兔模型的影响

目的：通过表面活性物质缺乏的兔肺模型,评估传统通气模式（ｃｏｎｖｅｎｔｉｏｎａｌ ｍｅｃｈａｎｉｃａｌ ｖｅｎｔｉｌａｔｉｏｎ,ＣＭＶ）与允许性高碳酸血症加最佳ＰＥＥＰ（ｐｅｒｍｉｓｓｉｖｅ ｈｙｐｅｒｃａｐｎｉａａｓｓｏｃｉａｔｅｄ ｗｉｔｈｉｄｅａｌＰＥＥＰｖｅｎｔｉｌａｔｉｏｎ,ＰＨＹ＋ ＰＥＥＰｉ）的通气模式对肺损伤的影响,了解肿瘤坏死因子α（ｔｕｍｏｒ ｎｅｃｒｏｓｉｓｆａｃｔｏｒα,ＴＮＦα） 与机械通气引起肺损伤（ｖｅｎｔｉｌａｔｏｒｉｎｄｕｃｅｄｌｕｎｇｉｎｊｕｒｙ,ＶＩＬＩ） 的关系。方法：１２ 只成年兔,以反复肺灌洗法制备表面活性物质缺乏兔肺模型。以ＣＭＶ（Ｃ组） 或ＰＨＹ＋ ＰＥＥＰｉ （Ｐ 组） 通气４ ｈ 后,测定通气前、后的支气管肺泡灌洗液（ｂｒｏｎｃｈｏａｌｖｅｏｌａｒ ｌａｖａｇｅ ｆｌｕｉｄ,ＢＡＬＦ）中ＴＮＦα含量和白细胞分类计数,测定肺水量,进行动脉血气分析和病理检查。结果：ＣＭＶ 组表现为明显的低氧血症,ＢＡＬＦ中较多的中性粒细胞数,总肺水量及血管外肺水量明显增多,肺内病理改变为较明显透明膜形成及炎性细胞聚集;而ＰＨＹ＋ ＰＥＥＰｉ 组引起较少的上述病理、生理变化。且ＣＭＶ 组ＢＡＬ     

Effect of hyperventilation on brain tissue oxygenation and cerebrovenous PO2 in rats

Previous studies have shown that cortical tissue oxygenation is impaired during hyperventilation. However, it is important to quantify the effect of hyperventilation on brain tissue PO(2) and cerebrovenous PO(2) simultaneously especially since cerebral venous oxygenation is often used to assess brain tissue oxygenation. The present study was designed to measure the sagittal sinus PO(2) (PvO(2)), brain tissue PO(2) in the thalamus (PtO(2)), and brain temperature (Bt) simultaneously during acute hyperventilation. Isoflurane-anesthetized rats were hyperventilated for 10 min during which time the arterial carbon dioxide tension (PaCO(2)) dropped from 40.3+4.9 mmHg to 23.5+2.8 mmHg. PtO(2) declined from 26.0+/-4.2 mmHg to 14.8+/-5.2 mmHg (P=0.004) while brain temperature decreased from 36.5+0.3 degrees C to 36.2+0.3 degrees C (P=0.02). However, PvO(2) and arterial blood pressure (BP) did not change during hyperventilation. The maintenance of PvO(2) when perfusion is thought to decline and PtO(2) decreases suggests that there may be a diffusion limitation, possibly due to selective perfusion. Therefore, cerebrovenous PO(2) may not give a good assessment of brain tissue oxygenation especially in conditions of acute hyperventilation, and deeper brain regions other than the cortex also show impaired tissue oxygenation following hyperventilation.     

Organisasjon og målsettinger: Refleksjoner omkring en personal-undersøkelse

Psykofarmaka: Odd Lingjaerde Tano: Oslo 1988. 1b. 572 s. N. kr. 448,-. 3. ut-gave.

Alice Miller slår til igjen

A. Der Gemiedene Schliissel: Alice Miller Suhrkamp Verlag, Frankfurt am Main 1988, ISBN 3-518-02226-1.

B. Das Verbannte Wissen: Alice Miller Suhrkamp Verlag, Frankfurt am Main 1988. ISBN 3-518-02227-X.

My work with borderline-patients: Harold F. Searles Forlag Jason Aronson, Inc., Northvale, New Jersey, London. 1986.     

Effects of Moderate Hyperventilation on Jugular Bulb Gases under Propofol or Isoflurane Anesthesia during Supratentorial Craniotomy

Background:

The optimal ventilated status under total intravenous or inhalation anesthesia in neurosurgical patients with a supratentorial tumor has not been ascertained. The purpose of this study was to intraoperatively compare the effects of moderate hyperventilation on the jugular bulb oxygen saturation (SjO₂), cerebral oxygen extraction ratio (O₂ER), mean arterial blood pressure (MAP), and heart rate (HR) in patients with a supratentorial tumor under different anesthetic regimens.

Methods:

Twenty adult patients suffered from supratentorial tumors were randomly assigned to receive a propofol infusion followed by isoflurane anesthesia after a 30-min stabilization period or isoflurane followed by propofol. The patients were randomized to one of the following two treatment sequences: hyperventilation followed by normoventilation or normoventilation followed by hyperventilation during isoflurane or propofol anesthesia, respectively. The ventilation and end-tidal CO₂ tension were maintained at a constant level for 20 min. Radial arterial and jugular bulb catheters were inserted for the blood gas sampling. At the end of each study period, we measured the change in the arterial and jugular bulb blood gases.

Results:

The mean value of the jugular bulb oxygen saturation (SjO₂) significantly decreased, and the oxygen extraction ratio (O₂ER) significantly increased under isoflurane or propofol anesthesia during hyperventilation compared with those during normoventilation (SjO₂: t = −2.728, P = 0.011 or t = −3.504, P = 0.001; O₂ER: t = 2.484, P = 0.020 or t = 2.892, P = 0.009). The SjO₂ significantly decreased, and the O₂ER significantly increased under propofol anesthesia compared with those values under isoflurane anesthesia during moderate hyperventilation (SjO₂: t = −2.769, P = 0.012; O₂ER: t = 2.719, P = 0.013). In the study, no significant changes in the SjO₂ and the O₂ER were observed under propofol compared with those values under isoflurane during normoventilation.

Conclusions:

Our results suggest that the optimal ventilated status under propofol or isoflurane anesthesia in neurosurgical patients varies. Hyperventilation under propofol anesthesia should be cautiously performed in neurosurgery to maintain an improved balance between the cerebral oxygen supply and demand.     

Hyperventilation causing symptomatic hypocalcaemia during labour in a parturient

Hyperventilation often occurs under stressful conditions and has been reported before, during or after anaesthesia and surgery. Hyperventilation is characterised by multiple somatic symptoms due to hypocalcaemia induced by respiratory alkalosis because of inappropriate hyperventilation. It should be managed as an emergency. Here, we report a case of 30 year old full term parturient presenting in labour in a highly anxious state, presenting with symptoms and signs of hypocalcaemia in the form of circumoral numbness along with carpal spasm. The patient was managed successfully with reassurance and intravenous calcium gluconate.