Brain haemodynamic effects of nasal continuous airway pressure in preterm infants of less than 30 weeks' gestation

AIM: To evaluate the hypothesis that increasing levels of nasal continuous positive airway pressure (NCPAP) may decrease cerebral blood volume (CBV) and cerebral oxygenation in infants with gestational age (GA) less than 30 weeks. METHODS: We prospectively studied a cohort of preterm infants treated with NCPAP using near-infrared spectroscopy (NIRS). The pressure limit of NCPAP was set at 2, 4, 6 and again 2 cm H(2)O for 30 min. RESULTS: Changes of pressure levels were not followed by significant changes of oxygenated haemoglobin (O(2)Hb), deoxygenated haemoglobin (HHb), cerebral intravascular oxygenation (HbD), oxidized-reduced cytochrome aa3 (CtOx), tissue oxygenation index (TOI), tissue haemoglobin index (THI) and cerebral blood volume (DeltaCBV). CONCLUSION: NCPAP at 2-6 cm H(2)O pressure levels did not affect cerebral oxygenation and CBV. These findings are reassuring and confirm the safety of NCPAP in preterm infants with GA less than 30 weeks.     

Brain hemodynamic effects of doxapram in preterm infants

BACKGROUND: Doxapram is a respiratory stimulant widely used for the treatment of idiopathic apnea of prematurity, although it has been demonstrated that it can induce a transient decrease of cerebral blood flow and that isolated mental delay in infants weighing <1,250 g is associated with the total dosage and duration of doxapram therapy. OBJECTIVES: To evaluate the effects of doxapram on cerebral hemodynamics in preterm infants using cerebral Doppler ultrasonography and near-infrared spectroscopy. METHODS: Preterm infants who required treatment with doxapram for apnea of prematurity unresponsive to caffeine were treated with doxapram at an hourly dose of 0.5 mg x kg(-1).h(-1), followed by 1.5 and 2.5 mg x kg(-1).h(-1). RESULTS: 20 preterm infants were studied. Doxapram induced a significant decrease of oxygenated hemoglobin (O(2)Hb) and cerebral intravascular oxygenation (HbD = O(2)Hb - HHb) and an increase of HHb and CtOx concentrations, while cerebral blood volume and cerebral blood flow velocity did not change. CONCLUSIONS: Doxapram infusion induces the increase of cerebral oxygen consumption and requirement and the contemporary decrease of oxygen delivery probably mediated by a decrease of cerebral blood flow. Caution must be recommended in prescribing this drug for apnea of prematurity.     

Cerebral hemodynamic changes in response to an executive function task in children with attention-deficit hyperactivity disorder measured by near-infrared spectroscopy

The aim of the present study was to evaluate the hemodynamic changes in both prefrontal regions induced by a cognitive task in children with a developmental attention-deficit disorder in comparison to normal controls using near-infrared spectroscopy (NIRS). A total of 11 boys with a mean age of 10.4 (+/-1.2) years that met the DSM-IV criteria for attention-deficit hyperactivity disorder (ADHD) participated in the study and were compared with 9 healthy age- and sex-matched controls. Using a trail-making test designed for the task of connecting numbers from 1-90 in four sets, changes in oxygenated (O2Hb) and deoxygenated (HHb) hemoglobin, tissue oxygenation index (TOI), and cerebral blood volume (CBV) were measured by near-infrared spectroscopy. During the first test set, designed as a short-attention task, the children with ADHD showed significant increases in O2Hb and CBV, whereas the controls showed no significant changes. During the 4 task cycles in which extended attention was demanded, both groups showed increases in O2Hb and CBV, but only the controls showed an additional increase in HHb in the left prefrontal region. In the ADHD group only, TOI showed an increase mainly on the left side. NIRS is a sensitive tool for measuring differences in hemodynamic changes between boys with ADHD and normal controls. Overall, the normal controls showed lateralized oxygen consumption in the left prefrontal cortex during an extended-attention task, whereas the boys with ADHD showed an imbalance between oxygenated and deoxygenated hemoglobin during the short- and extended-attention tasks.     

Monitoring of cerebral oxygenation during hypoxic gas management in congenital heart disease with increased pulmonary blood flow

In the preoperative management of congenital heart disease (CHD) with increased pulmonary blood flow, hypoxic gas management to control pulmonary blood flow is useful. However, the cerebral oxygenation state has rarely been studied, and there is concern about neurologic development. In eight infants with CHD accompanied by increased pulmonary blood flow, hypoxia was induced after a 1-h baseline period in room air (FiO2, 0.21). The infants were simultaneously monitored in both the front-temporal region and the right-brachial region for 90 min using near-infrared spectroscopy (NIRS). The minimum SaO2 (pulse oximetry) after hypoxic gas administration was 80.8 +/- 2.9% when the minimum FiO2 was 16.2 +/- 1.1%. With a decrease in SaO2, oxy-Hb (O2Hb) decreased and total Hb [cHb: O2Hb + deoxy-Hb (HHb)] increased in both regions in the majority of infants. HHb increased in both regions with a decrease in SaO2. The maximum change in the tissue oxygenation index (TOI: O2Hb/cHb x 100) was -8.3 +/- 2.6% in the front-temporal region and -3.6 +/- 2.3% in the right-brachial region. Cerebral oxygenation decreased despite an increase in cerebral blood flow during hypoxic gas management. The change in TOI was < or =10% when the SaO2 was > or =80%. Safer control of SaO2 should be maintained over 80% for hypoxia management in CHD based on the results of the present study.     

Effect of blood transfusions on cerebral haemodynamics in preterm infants

Aim: To assess the possible cerebral haemodynamic changes occurring in preterm infants after blood transfusions. Methods: Preterm infants who had undergone blood transfusions were prospectively studied using both near infrared spectroscopy and cerebral Doppler ultrasonography. Results: Fourteen infants (mean gestational age 29.6 wk, SD 2.6; mean birthweight 1430 g, SD 332) were studied at the mean age of 29 (SD 14) d. A significant increase in oxygenated haemoglobin (O 2 Hb), deoxygenated haemoglobin (HHb), mixed cerebral oxygen saturation (SmO 2 ) and change in cerebral blood volume occurred after transfusion. Between ultrasound parameters, we found a decrease in diastolic velocity and an increase in resistance index.

Conclusion: Blood transfusions improve cerebral oxygen supply and induce a decrease in cerebral blood volume, probably due to an increase in cerebral vessel resistance.     

Effects of midazolam and morphine on cerebral oxygenation and hemodynamics in ventilated premature infants

BACKGROUND: Midazolam sedation and morphine analgesia are commonly used in ventilated premature infants. OBJECTIVES: To evaluate the effects of midazolam versus morphine infusion on cerebral oxygenation and hemodynamics in ventilated premature infants. METHODS: 11 patients (GA 26.6-33.0 weeks, BW 780-2,335 g) were sedated with midazolam (loading dose 0.2 mg/kg, maintenance 0.2 mg/kg/h) and 10 patients (GA 26.4-33.3 weeks, BW 842-1,955 g) were sedated with morphine (loading dose 0.05 mg/kg, maintenance 0.01 mg/kg/h). Changes in oxyhemoglobin (Delta cO2Hb) and deoxyhemoglobin (Delta cHHb) were assessed using near infrared spectrophotometry. Changes in cHbD (= Delta cO(2)Hb - Delta cHHb) reflect changes in cerebral blood oxygenation and changes in concentration of total hemoglobin (Delta ctHb = Delta cO2Hb + Delta cHHb) represent changes in cerebral blood volume (DeltaCBV). Changes in cerebral blood flow velocity (DeltaCBFV) were intermittently measured using Doppler ultrasound. Heart rate (HR), mean arterial blood pressure (MABP), arterial oxygen saturation (saO2) and transcutaneous measured pO2 (tcpO2) and pCO2 (tcpCO2) were continuously registered. Statistical analyses were carried out using linear mixed models to account for the longitudinal character study design. RESULTS: Within 15 min after the loading dose of midazolam, a decrease in saO2, tcpO2 and cHbD was observed in 5/11 infants. In addition, a fall in MABP and CBFV was observed 15 min after midazolam administration. Immediately after morphine infusion a decrease in saO2, tcpO2 and cHbD was observed in 6/10 infants. Furthermore, morphine infusion resulted in a persistent increase in CBV. CONCLUSIONS: Administration of midazolam and morphine in ventilated premature infants causes significant changes in cerebral oxygenation and hemodynamics, which might be harmful.     

Cerebral blood flow and left ventricular output in spontaneously breathing, newborn preterm infants treated with caffeine or aminophylline

Aminophylline and caffeine are commonly used for prophylaxis of apnea in premature infants. Previous studies have indicated different effects of the drugs on cerebral circulation. Therefore, we have compared the acute effects of bolus administration of caffeine citrate or aminophylline on left ventricular output, heart rate, blood pressure and global cerebral blood flow. The study group consisted of 33 newborn, spontaneously breathing, preterm infants randomly assigned to receive either aminophylline 5mg/kg (n = 19) or caffeine citrate 20mg/kg ( n = 14). Two hours after iv drug administration, global cerebral blood flow measured by the Xe-clearance technique was significantly lower after aminophylline than after caffeine (mean(SD)): 13.2 (+2.9/ - 2.3) versus 17.2 (+7.1/ - 5.1) ml/100 g/min) (p = 0.01). There were no other statistically significant differences in circulatory or ventilatory parameters between the groups. Further studies are needed to clarify the clinical relevance of these results.     

Effects of repeated indomethacin administration on cerebral oxygenation and haemodynamics in preterm infants: Combined near infrared spectrophotometry and Doppler ultrasound study

The objectives of this study were to evaluate the effect of repeated indomethacin administration on cerebral oxygenation in relation to changes in cerebral blood flow velocity (CBFV) and other relevant physiological variables. Fourteen preterm infants with patent ductus arteriosus were studied during three subsequent indomethacin bolus administrations with intervals of 12 and 24 h. Changes in concentration of oxyhaemoglobin (cO₂Hb), deoxyhaemoglobin (cHHb) and oxidized cytochrome aa₃ (cCyt.aa₃) in cerebral tissue and changes in cerebral blood volume (CBV) were measured by near infrared spectrophotometry; changes in mean CBFV in the internal carotid artery were measured by pulsed Doppler ultrasound. Simultaneously heart rate, transcutaneouspO₂ andpCO₂, arterial O₂ saturation and blood pressure were measured. All variables were continuously recorded until 60 min after indomethacin administration. Within 5 min after each indomethacin administration, significant decreases in CBFV, CBV and cO₂Hb and cCyt.aa₃ were observed which persisted for at least 60 min, while cHHb increased or did not change at all. There were no changes in the other variables recorded. These data demonstrate that indomethacin administration is accompanied by a reduction in cerebral tissue oxygenation due to decreased cerebral blood flow. Therefore, low arterial oxygen content, either caused by low arterial O₂ saturation or by low haemoglobin concentration, may be a contraindication for indomethacin treatment in preterm infants.     

Effect of tilting on cerebral hemodynamics in preterm and term infants

Tilting is known to cause changes in hemodynamics due to hydrostatic pressure. The present study is an analysis of changes in cerebral hemodynamics measured by near infrared spectroscopy (NIRS) following tilting up and down in preterm and term infants. A significantly different effect of tilting up in comparison to tilting down on total hemoglobin in preterm infants and on the 'hemoglobin oxygenation index' in preterm and term infants was observed. In preterm infants, tilting up and down had a significantly different effect on cerebral blood volume (CBV), with an increase after tilting down and a decrease after tilting up. In term infants, tilting had no significant effect on CBV comparing these two procedures. We think that NIRS provides a good method to measure cerebral hemodynamics following tilting, whereby different reactions in infants of different postconceptional age can be observed.     

Influence of intravenous sildenafil on cerebral oxygenation measured by near-infrared spectroscopy in infants after cardiac surgery

Sildenafil (Viagra) has been shown to be an effective pulmonary vasodilator and is increasingly used in patients with pulmonary hypertension. Its effects on the cerebral circulation are unclear and have not yet been described. We investigated the effect of i.v. sildenafil treatment on cerebral oxygenation in 13 children with elevated pulmonary vascular resistance due to congenital heart defects after cardiac surgery using near-infrared spectroscopy (NIRS). Median age was 4.5 mo, and median weight was 5.5 +/- 1.8 kg. Sildenafil was administered in three steps of 15 min each with cumulative doses of 0.025, 0.1, and 0.25 mg/kg. We examined the changes of oxygenated hemoglobin (HbO2), deoxygenated hemoglobin (HHb), total hemoglobin (tHb) concentration, cytochrome oxidase (CytOx) oxygenation, and cerebral tissue oxygenation index (TOI) in 13 children. A significant increase in cerebral HbO2 and tHb at the beginning of i.v. sildenafil administration with a decrease in HHb was observed. These changes led to a significant elevation in cerebral TOI from 63.4 +/- 2.5% to 65.7 +/- 2.8%, whereas mean systemic arterial pressure and arterial oxygen partial pressure tended to decrease. In conclusion, we observed a reversible increase of HbO2, tHb, and hemoglobin oxygen saturation in the scanned tissue section after i.v. sildenafil administration. These findings may be clinically relevant because they indicate that after cardiac surgery, sildenafil may increase cerebral blood flow (CBF), probably due to general endothelial dysfunction after cardiopulmonary bypass (CPB).     

Cerebral hemodynamics and major surgery

AIM: Near infrared spectroscopy (NIRS) is a non invasive optical technique to assess the monitoring of oxygenation and cerebral hemodynamics. Aim of our study was to value cerebral hemodynamics during major surgery to reduce the period of possible modifications of cerebral oxygenation. METHODS: Twenty-five newborns which underwent surgical intervention (8 diaphragmatic hernia, 8 esophageal atresia, 1 neck lymphangioma, 8 intestinal malformation) were studied during surgery by means of NIRS (NIRO 300), using an electrode applied to the scalp in the frontoparietal region. We monitored the Tissue Oxygenation Index (TOI) as well as the changes in concentration of total haemoglobin (tHb), oxygenated haemoglobin (O2Hb) and deoxygenated haemoglobin (HHb). The changes have been expressed as difference from the basal value recorded at the beginning of surgery. RESULTS: During the surgical intervention O2Hb, tHb and TOI decreased (DeltaO2Hb=-11.4+/-6.5 microM; P<0.001; DeltatHb=- 7.54+/-4.3 microM, P<0.05; microTOI=-12.5+/-5.5%, P<0.001), and HHb increased (DeltaHHb=+4.80+/-2.30 microM, P<0.001); the greatest changes occurred when the viscera were positioned into the abdomen (in diaphragmatic hernia and intestinal malformation). CONCLUSION: The present study suggests that NIRS, during major surgery, is able to monitor oxygenation and cerebral hemodynamics thus allowing a real time evaluation of some intraoperative procedure aftereffects that, if timely modified, could reduce cerebral hypoxia risks.     

Effect of tilting on cerebral haemodynamics in preterm infants with periventricular leucencephalomalacia

Aim: Measurement of cerebral haemodynamics to detect impaired cerebral blood flow and impaired cerebral autoregulation might make prevention of brain lesions and especially periventricular leucencephalomalacia (PVL) achievable. Methods: Changes in cerebral blood volume (CBV) and the cerebral haemoglobin oxygenation index (cHbD) following tilting up and down in 10 preterm infants with PVL and 25 preterm infants without PVL, measured by near infrared spectroscopy (NIRS), were analysed. Tilting manoeuvres were recorded with a polysomnographic system in combination with NIRS. CBV and cHbD of the baseline phase (1 min before tilting) were compared with data from the post-tilting phase (1 min after tilting). Results: Changes in CBV and cHbD after tilting were significantly pronounced in infants with PVL compared with infants without PVL. CBV decreased in infants with PVL, by -0.099 ± 0.081 ml 100 g ^-1 brain (mean ± SD) after tilting up, and increased by 0.106 ± 0.104 ml 100 g ^-1 brain after tilting down. CBV decreased in infants without PVL, by -0.041 ± 0.068 ml 100 g ^-1 brain after tilting up, and increased by 0.020 ± 0.096 ml 100 g ^-1 brain after tilting down. cHbD showed similar changes after tilting.

Conclusion: Changes in CBV and cHbD after tilting were pronounced in preterm infants with PVL and this may indicate reduced cerebral autoregulatory capacity.     

The effect of blood transfusion and haemodilution on cerebral oxygenation and haemodynamics in newborn infants investigated by near infrared spectrophotometry

The objective of this study was to investigate the influence of blood transfusion and haemodilution on cerebral oxygenation and haemodynamics in relation to changes in cerebral blood flow velocity (CBFV) and other relevant physiological variables in newborn infants. Thirteen preterm infants with anaemia (haematocrit < 0.33) and ten infants with polycythaemia (haematocrit > 0.65) were studied during blood transfusion and haemodilution respectively using adult red blood cells and partial plasma exchange transfusion. Changes in cerebral concentrations of oxyhaemoglobin (cO₂Hb), deoxyhaemoglobin (cHHb), total haemoglobin (ctHb), (oxidized - reduced) cytochrome aa₃ (cCyt.- aa₃) were continuously measured using near infrared spectrophotometry throughout the whole procedure. Simultaneously, changes of mean CBFV in the internal carotid artery were continuously measured using pulsed Doppler ultrasound. Heart rate, transcutaneous partial pressure of oxygen and carbon dioxide, and arterial O₂ saturation were continuously and simultaneously measured. Blood transfusion resulted in increase of cO₂Hb, cHHb, ctHb and red cell transport (product of CBFV and haematocrit), whereas CBFV decreased. The increase of cO₂Hb exceeded that of cHHb, reflecting improvement of cerebral O₂ supply. Haemodilution resulted in a decrease of cO₂Hb, cHHb and ctHb, whereas CBFV increased. Red cell transport was unchanged. The decrease of cO₂Hb exceeded that of cHHb, reflecting decreased cerebral O₂ supply. cCyt.aa₃ decreased after blood transfusion and remained unchanged after haemodilution, but the reliability of these results is uncertain. With the exception of a small, but significant increase in transcutaneous partial pressure of oxygen after blood transfusion, the other variables showed no changes. Each blood withdrawal during exchange transfusion resulted in only a significant increase in heart rate without changes in the other variables measured, suggesting unchanged cerebral perfusion. Conclusion In newborn infants blood transfusion in anaemia results in improvement of cerebral oxygenation, but haemodilution in polycythaemia does not improve cerebral oxygenation despite possible improvement of cerebral perfusion. Received: 21 December 1995 and in revised form: 29 August 1996 / Accepted: 4 September 1996     

Surgical closure of patent ductus arteriosus reduces the cerebral tissue oxygenation index in preterm infants: a near-infrared spectroscopy and Doppler study

BACKGROUND: The aim of this study was to investigate the effects of patent ductus arteriosus (PDA) ligature on cerebral oxygen saturation, cerebral blood volume (CBV) and cerebral blood flow velocity by means of near-infrared spectroscopy (NIRS) and transcranial Doppler simultaneous examinations. METHODS: This is an observational study considering 16 babies of gestational age 24-34 weeks diagnosed with PDA who underwent surgical ligation. The cerebral oxygen saturation, CBV and blood gases values were obtained 35 min before ligation, so also around the 14th and 27th min after the clip's insertion. RESULTS: Cerebral oxygen saturation, measured as tissue oxygenation index (TOI), decreased significantly after PDA ligation from a basal value of 61.1 (3.8) before surgery to 56.6 (3.3) and 55.8 (2.6)%, for the 14th and 27th min, respectively (P<0.04). CBV before and after clipping was unvaried. A negative correlation was found between DeltapH and DeltaCBV after ligation (R=0.52, P=0.03), whilst a positive correlation was found between DeltaCBV and DeltaP(aCO2) (R=0.62, P=0.009). pH increased at the 27th min post-ligation. CONCLUSIONS: NIRS is a tool for obtaining information on cerebral oxygen saturation and CBV changes during surgical PDA ligation at the bedside. A fall in TOI suggests an increased oxygen extraction during PDA surgery. The lack of increase in DeltaCBV or in diastolic flow velocity show that the PDA before the clipping did not limit cerebral blood flow, the drop in TOI suggests increased oxygen consumption over the clip and the need for accurate monitoring of oxygen utilization after the surgical treatment.     

Cerebral blood volume measured using near-infrared spectroscopy and radiolabels in the immature lamb brain.

Near-infrared spectroscopy (NIRS) is a technique that is increasingly being used for the noninvasive measurement of cerebral blood volume (CBV) in newborn infants, but it has not been fully validated against established methods. These experiments in immature lambs (gestation 92+/-1 d, mean+/-SEM) compared CBV measured using NIRS-derived estimates of oxygenated Hb (n = 5) with CBV estimated with radiolabeled indicators (125I-labeled serum albumin and 51Cr-labeled red blood cells, n = 10). Total brain CBV (mL/100 g tissue) measured using NIRS was 2.5+/-0.2 compared with 2.5+/-0.2 using radiolabels (NS). Regional tissue plasma, red blood cells, and whole blood volumes from radiolabels varied significantly (p < or = 0.05) throughout the brain. Whole blood volume (mL/100 g tissue) was largest in choroid plexus (16.2+/-2.1) and least in white matter (0.7+/-0.1) with a significant hierarchy evident among regions: choroid plexus > cerebellum > cortex > brain stem = midbrain > white matter. Regional plasma and red blood cell distributions were similar to whole blood, being highest in choroid plexus (13.0+/-1.6 and 3.2+/-0.9, respectively), and least in white matter (0.8+/-0.1 and 0, respectively). These data from the immature lamb brain indicate that total CBV measured with NIRS is essentially identical with the volumes obtained using intravascular radiolabels. Among cerebral regions, white matter contributes little to the global blood volume measured with NIRS because its red blood cell content is very low.     

Brain cell function during hypoxemia in near-term lambs: a near-infrared spectroscopy study

BACKGROUND: Sufficient O2 supply to the brain is necessary for adequate cerebral energy metabolism, function and growth. OBJECTIVES: To elucidate the relation between changes in cerebral arterial O2 content and cerebral O2 supply and changes in the oxygenation state of cerebral hemoglobin, and to determine whether concentration changes in oxyhemoglobin (DeltacO2Hb), deoxyhemoglobin (DeltacHHb), and cerebral arterial oxygenation (DeltacHbD; the difference between DeltacO2Hb and DeltacHHb), and cerebral blood volume (DeltaCBV) can be used to assess the decline in brain cell function during hypoxemia in lambs born near term. METHODS: 17 preterm lambs were delivered at a mean gestational age of 133 days. Decreases in cerebral arterial oxygen content were induced by a stepwise reduction in inspired oxygen concentration. Mean values of all continuous variables were calculated over the last 180 s of each hypoxemic level. Cerebral arterial blood gases were analyzed at the end of each level to calculate cerebral arterial O2 content and cerebral O2 supply. RESULTS: Changes in cerebral arterial O2 content and cerebral O2 supply were positively linearly related with DeltacO2Hb and DeltacHbD, and negatively with DeltacHHb and the concentration changes in total hemoglobin. Electrocortical brain activity remained stable until the cO2Hb and cHbD decreased to >3.0 +/- 0.9 and >8.1 +/- 1.9 (mean +/- SD) micromol/100 g, respectively, and cHHb and CBV increased to >4.3 +/- 1.7 and 1.37 +/- 0.48 ml/100 g, respectively, as compared to baseline. CONCLUSIONS: Changes in cerebral arterial O2 content and cerebral O2 supply are adequately reflected by changes in the oxygenation state of cerebral hemoglobin. Concentration changes in DeltacO2Hb, DeltacHHb, DeltacHbD and DeltaCBV can be used to assess the decline in brain cell function during hypoxemia in lambs born near term.     

Aminophylline influences cerebral hyperperfusion after severe birth hypoxia

Doppler sonographic investigations have presented cerebral hyperperfusion in neonates after severe asphyxia. Neonates with disturbed cerebral blood flow velocity (CBFV) tend to have poor outcomes. The purpose of this clinical study was to examine the influence of aminophylline on cerebral hyperperfusion. An intravenous bolus of 4 mg/kg aminophylline was given to nine neonates with Doppler sonographic signs of cerebral hyperperfusion. CBFV was determined before, 5 min, 60 min and 120 min after aminophylline administration and on the following day. After aminophylline the mean systolic (56.5 vs. 41.6 cm/s) and end diastolic (21.0 vs. 12.3 cm/s) blood flow velocity decreased and the mean pulsatility index (0.83 vs. 1.1) increased significantly. Repeated measurements showed a decrease in blood flow velocities and an increase in pulsatility index on the following days. Heart rate, mean arterial blood pressure and pCO₂ were not significantly changed. We conclude that aminophylline influences cerebral hyperperfusion in neonates with disturbed autoregulation.     

早期监测脑氧饱和度及脑血流参数在脓毒性休克患儿预后中的意义

目的 探讨脑氧饱和度(rScO 2)及脑血流参数氧合血红蛋白浓度(ΔO 2 Hb)、还原血红蛋白浓度(ΔHHb)和血红蛋白浓度指数(THI)在判断脓毒性休克患儿预后中的价值.方法 选择2017年10月—2019年10月收治的脓毒性休克患儿50例.入重症监护病房(ICU)即刻开始监测患儿血流动力学参数,包括平均动脉血压(...     

CSF removal in infantile posthemorrhagic hydrocephalus results in significant improvement in cerebral hemodynamics

Rational intervention in infants with posthemorrhagic hydrocephalus (PHH) would be facilitated greatly by bedside measure of impaired cerebral perfusion, as there is substantial evidence that impaired perfusion and oxidative metabolism contribute to irreversible brain injury in hydrocephalus. Near-infrared spectroscopy (NIRS) measures changes in the cerebral concentration of oxygenated and deoxygenated hemoglobin and oxidized cytochrome oxidase at the bedside of infants continuously and noninvasively. The total hemoglobin and the hemoglobin difference signal are derived from the sum and difference, respectively, of oxygenated and deoxygenated hemoglobin. Changes in total hemoglobin reflect changes in cerebral blood volume; our previous work has shown that changes in hemoglobin difference signal reflect changes in cerebral blood flow. We hypothesized that cerebrospinal fluid (CSF) removal in infants with PHH would result in significant increases in cerebral perfusion, cerebral blood volume, and oxidative metabolism, as measured by NIRS. Continuous NIRS recordings were performed during CSF removal on 16 infants with PHH. There was a statistically significant increase in oxygenated hemoglobin (p < 0.001), total hemoglobin (p = 0.001), and hemoglobin difference signal (p = 0.006), but not oxidized cytochrome oxidase, accompanying CSF removal. There was no significant correlation between either the volume of CSF removed (in milliliters per kilogram body weight) or the opening pressure and the change in any of the measured or calculated NIRS signals. These findings demonstrate the pronounced effect of CSF removal on cerebral perfusion in infants with PHH. NIRS may be a useful technique to detect impending cerebral ischemia in such infants and thereby provide a means to guide the rational management of PHH.     

Blood withdrawal and infusion via umbilical catheters: effect on cerebral perfusion and influence of ibuprofen

Withdrawal and infusion of blood via umbilical catheters can affect cerebral blood flow in preterm infants. We compared the effects on cerebral perfusion of 3 ml/kg blood withdrawal and infusion via umbilical arterial (UAC) and venous (UVC) catheters in 16 infants < or =32 weeks gestation, age <24 h, on mechanical ventilation. Near infrared spectroscopy was used to monitor changes in cerebral oxy- and deoxyhemoglobin, total cerebral hemoglobin (an index of cerebral blood volume; CBV) and HbD (an index of cerebral intravascular oxygenation). In 10 infants the study was repeated 1 h after intravenous administration of 10 mg/kg ibuprofen as prophylaxis against PDA. Withdrawal and infusion via the UVC caused significant MABP and concordant HbD and CBV changes. Smaller modifications were seen following blood withdrawal and infusion via the UAC. Ibuprofen attenuated cerebral hemodynamic changes associated with withdrawal, but not infusion, from UAC and UVC.