Comparison of gastric mucosal pH and clinical judgement in critically ill patients

OBJECTIVES: To compare gastric tonometry (pHi) with estimates of pHi in ill injured patients, and to correlate pHi with haemodynamic variables. DESIGN: Prospective, non-interventional study. SETTING: ICU of Level I trauma centre, USA. MAIN OUTCOME MEASURES: 154 gastric tonometry measurements were compared with physicians' estimates of adequacy of resuscitation. Resuscitation was categorised as inadequate (pHi < 7.35) or adequate (pHi> or = 7.35). Measured and estimated pHi were also compared with oxygen delivery, oxygen consumption, cardiac index, mixed venous O2 saturation, and critical illness scores. RESULTS: Estimated pHi was often higher than measured pHi in the judgement of all four surgical intensive care physicians. Measured pHi correlated positively with mixed venous O2 tension (r = 0.21). There were significant negative correlations between measured pHi and both oxygen delivery (r = -0.25) and oxygen consumption (r = 0.28). Estimated pHi correlated positively with mean arterial pressure (r = 0.21) and hospital day (r = 0.26); it correlated negatively with pulmonary arterial elastance (r = -0.35). CONCLUSION: Experienced intensive care physicians tended to overestimate visceral perfusion, which suggests that gastric tonometry adds useful information over and above routine haemodynamic indices. Arterial blood pressure and mixed venous oxygen saturation correlated better with measured pHi than with other indices of perfusion.     

Effect of alpha(alpha)-cross-linked hemoglobin and pyridoxalated hemoglobin polyoxyethylene conjugate solutions on gastrointestinal regional perfusion in hemorrhagic shock

BACKGROUND: Hemoglobin-based blood substitutes may cause vasoconstriction, which could limit organ perfusion during trauma resuscitation. We investigated the effect of two hemoglobin solutions on regional blood flow and mucosal perfusion in the gastrointestinal tract in a hemorrhagic shock model. METHODS: Twenty-four swine were bled 30% of blood volume over 1 hour. Six additional animals were anesthetized and monitored but did not undergo hemorrhage. Bled animals were resuscitated with alpha(alpha)-hemoglobin (alpha(alpha)Hb), pyridoxalated hemoglobin polyoxyethylene conjugate (PHP), shed blood, or lactated Ringer's solution. Regional blood flow was measured by radiolabeled microspheres. Gastric mucosal perfusion was estimated by measuring intramucosal pH (pHi) by tonometry. RESULTS: PHP and shed blood restored small-bowel flows to sham values, whereas lactated Ringer's solution and alpha(alpha)Hb did not. Shed blood and PHP, but not alpha(alpha)Hb, restored cardiac index (CI) to baseline (p < 0.05). Mean pulmonary artery pressure was elevated over baseline with alpha(alpha)Hb and PHP and remained elevated with alpha(alpha)Hb (p < 0.05). pHi was significantly lower after resuscitation with PHP than with other fluids. CONCLUSION: PHP was efficacious in restoring CI and small-bowel flow, but the pHi remained low, indicating possible continued mucosal ischemia. Alpha(alpha)Hb led to limited recovery of CI and small-bowel blood flow but restored pHi close to baseline. Shed blood was efficacious in restoration of pHi, gastrointestinal blood flows, and systemic hemodynamics.     

Ovarian blood flow in conscious and anaesthetized pregnant rabbits near term and the influence of arterial blood gas tensions

Total ovarian, luteal and stromal blood flows were measured with radioactive microspheres (25 mum diameter) in 7 rabbits anaesthetized with sodium pentobarbitone and 23 conscious rabbits at Day 28 of gestation. Despite major differences in cardiac output, arterial PO2, PCO2, pH and base status, ovarian tissue blood flows were similar in both groups. In the conscious rabbits total ovarian blood flow was negatively related to arterial pressure, and luteal blood flow was negatively related to pressure and arterial pH. In the anaesthetized rabbits ovarian stromal blood flow was positively related to arterial PO2.     

Effects of dobutamine, norepinephrine and epinephrine on intramucosal pH and hemodynamics of dogs during endotoxic shock

This study assessed the effects of dobutamine (DOB), epinephrine (EPI) and norepinephrine (NE) on gastric tissue oxygenation indicated by gastric intramucosal pH (pHi) and hemodynamics in dogs subjected to endotoxic shock. Twenty-four dogs were assigned to four groups of 6 dogs each: endotoxin without catecholamine and endotoxin with DOB, or EPI or NE. Endotoxic shock was induced by intravenous injection of 3 mg/kg of E. coli over 1 min, with an additional 3 mg/kg over the next 2 hrs. Dogs were resuscitated with normal saline to maintain pulmonary capillary wedge pressure (PCWP) near baseline levels. Catecholamines were infused at 0.1, 0.4 and 1.6 micrograms/kg/min (EPI and NE) and 2.5, 5.0 and 10.0 micrograms/kg/min (DOB) for 30 min at each rate. After 2 hrs of endotoxemia, mean arterial pressure (MAP) and cardiac index (CI) and oxygenation delivery index (DO2I) for all dogs decreased by 46.5%, 43.9% and 15.1% respectively, while pHi decreased from 7.47 to 7.10. Endotoxemia increased blood lactate by 142%. Following fluid resuscitation, EPI (1.6 micrograms/kg/min) further increased lactate by 178% (1.22 to 3.4 mmol/L). No correlation was found between tonometry pHi and lactate (R2 = 0.003), pHi and pHa (R2 = 0.231), pHi and DO2I (R2 = 0.056) nor between intramucosal PCO2 and PaCO2 (R2 = 0.005). pHi did not reflect the improvements in cardiovascular hemodynamics observed following administration of catecholamines. NE improved MAP, CI and DO2I whereas DOB produced similar effects as NE but further reduced SVR. EPI produced similar effects as NE. DOB, NE and EPI further decreased pHi. EPI significantly (P < 0.05) increased blood lactate levels more than DOB and NE.     

Left ventricular function during respiratory failure

Indirect measures of left ventricular function were studied in seven patients with respiratory failure secondary to chronic obstructive pulmonary disease to determine if there were a relationship between left ventricular function and treatment of the pulmonary disease. All patients were studied during acute episodes while in respiratory failure having arterial Pco2 (Paco2) values greater than 49 torr with no clinical evidence of left ventricular failure. Indirect methods to evaluate left ventricular function included the use of the Swan-Ganz catheter for pulmonary capillary wedge pressure measurement, systolic time intervals, and cardiac output. There was improvement in left ventricular function with treatment of the respiratory failure manifested by decreases in the wedge pressure and pre-ejection period/left ventricular ejection time ratio, and an increase in the dp/dt/pulmonary capillary wedge pressure with treatment of the chronic obstructive pulmonary disease. The improvement in left ventricular function suggests that there is a depression of left ventricular function in respiratory failure. The depressed function improved with therapy of the lung disease without additional medication directed at cardiac function.     

Ventilatory responses to CO2 in the chicken: intrapulmonary and systemic chemoreceptors

The independent effects of pulmonary and arterial Pco2 on respiratory amplitude (RA) and respiratory frequency (f) were studied in unidirectionally ventilated chickens anesthetized with phenobarbital (160 mg-kg-1). Pulmonary Pco2 was set by the level of PIco2 ventilating the vascularly isolated right lung (VIL), whereas the systemic arterial Pco2 was set by the level of PIco2 ventilating the denervated left or gas exchange lung (GEL). The following results were obtained: 1) Increasing the PIco2 to the VIL from 0 to 35 torr and maintaining Paco2 constant at 2. torr increased RA from apnea to 76% of the animals' maximal hypercapnic response and decreased f: further increases in PIco2 to VIL had only minimal effects on RA and f. 2) increasing Paco2 from 19 to 61 torr and maintaining pulmonary Pco2 constant increased RA and decreased further increases in Paco2 had only slight effects on RA ulmonary chemoreflex and can dominate the control of RA during hypocapnic conditions, and (2) systemic CO2-sensitive chemoreceptors dominate the control of RA during hypercapnic conditions. It is suggested that the intrapulmonary chemoreceptors may act as a sensory system which plays a pertinent role in the regulation of parabronchial ventilation.     

Intraabdominal pressure and gastric intramucosal pH: is there an association?

This study evaluated the potential association between increased intraabdominal pressure (IAP) and abnormally low gastric intramucosal pH (pHi) (/= 20 mmHg and a pHi of 相似文献   

In vivo microdialysis of 2-deoxyglucose 6-phosphate into brain: a novel method for the measurement of interstitial pH using 31P-NMR

A unique method for simultaneously measuring interstitial (pHe) as well as intracellular (pHi) pH in the brains of lightly anesthetized rats is described. A 4-mm microdialysis probe was inserted acutely into the right frontal lobe in the center of the area sampled by a surface coil tuned for the collection of 31P-NMR spectra. 2-Deoxyglucose 6-phosphate (2-DG-6-P) was microdialyzed into the rat until a single NMR peak was detected in the phosphomonoester region of the 31P spectrum. pHe and pHi values were calculated from the chemical shift of 2-DG-6-P and inorganic phosphate, respectively, relative to the phosphocreatine peak. The average in vivo pHe was 7.24+/-0.01, whereas the average pHi was 7.05+/-0.01 (n = 7). The average pHe value and the average CSF bicarbonate value (23.5+/-0.1 mEq/L) were used to calculate an interstitial Pco2 of 55 mm Hg. Rats were then subjected to a 15-min period of either hypercapnia, by addition of CO2 (2.5, 5, or 10%) to the ventilator gases, or hypocapnia (PCO2 < 30 mm Hg), by increasing the ventilation rate and volume. pHe responded inversely to arterial Pco2 and was well described (r2 = 0.91) by the Henderson-Hasselbalch equation, assuming a pKa for the bicarbonate buffer system of 6.1 and a solubility coefficient for CO2 of 0.031. This confirms the view that the bicarbonate buffer system is dominant in the interstitial space. pHi responded inversely and linearly to arterial PCO2. The intracellular effect was muted as compared with pHe (slope = -0.0025, r2 = 0.60). pHe and pHi values were also monitored during the first 12 min of ischemia produced by cardiac arrest. pHe decreases more rapidly than pHi during the first 5 min of ischemia. After 12 min of ischemia, pHe and pHi values were not significantly different (6.44+/-0.02 and 6.44+/-0.03, respectively). The limitations, advantages, and future uses of the combined microdialysis/31P-NMR method for measurement of pHe and pHi are discussed.     

The effect of acute hypocapnia on middle cerebral artery transcranial Doppler velocity during orthotopic liver transplantation: changes at reperfusion

This study examines the effects of acute hypocapnia, instituted prior to reperfusion of the graft liver, on the middle cerebral artery (MCA) Doppler blood flow velocity response to reperfusion during orthotopic liver transplantation in humans. Seventeen patients with chronic liver disease underwent continuous, noninvasive Doppler imaging of the MCA. Hyperventilation to an end-tidal Pco2 of 25 +/- 1 mm Hg was associated with a decrease in mean MCA flow velocity (FVm) from 51.6 +/- 5.7 to 37.0 +/- 3.3 cm/s (P < 0.05). After reperfusion, the Paco2 increased from 32 +/- 1 to 40 +/- 1 mm Hg (P < 0.05), mean arterial pressure (MAP) decreased from 76 +/- 3 to 60 +/- 2 mm Hg, and the FVm increased from 37.0 +/- 3.3 to 54.0 +/- 4.7 cm/s (P < 0.05). FVm increased postreperfusion despite prior hyperventilation, decreased MAP, and abrupt increases in central venous and pulmonary artery pressure, but FVm did not exceed the prereperfusion level. In 10 of the 17 patients, the baseline FVm versus Paco2 response slopes and Paco2 measured postreperfusion were used to predict the FVm response to Paco2 after reperfusion. The slopes were similar to those reported for anesthetized patients without liver disease. Predicted FVm exceeded measured FVm in 9 of the 10 patients. We conclude that mild hyperventilation prior to reperfusion of the graft liver prevents FVm increases above prereperfusion baseline level.     

HELLP syndrome: undiagnosed in a case of impending rupture of uterus. A case report

Eleven patients with chronic renal failure who were being treated with haemodialysis three times a week were monitored for a total of 34 haemodialysis sessions. Erythrocyte 2,3-biphosphoglycerate (2,3-BPG) concentration was analysed immediately before initiation of bicarbonate haemodialysis and 1 h afterwards. The 2,3-BPG concentration was expressed relative to the haemoglobin tetramer (Hb4) concentration as the 2,3-BPG/Hb4 ratio and compared with blood gas analyses and biochemical variables important for characterizing uraemia. During the first hour of haemodialysis the 2,3-BPG/Hb4 ratio decreased (p < 0.002), but the magnitude of the decrease did not significantly correlate with the 2,3-BPG/Hb4 ratio measured before haemodialysis (p=0.104). The decrease is most likely to be caused by the haemodialysis procedure itself. Mechanical stress on the erythrocytes is believed to cause the 2,3-BPG to escape; it is then removed by haemodialysis. Physiologically, an increase in 2,3-BPG would be expected to counteract the hypoxia which is frequently observed during haemodialysis. However, the present results show the opposite, a decrease in 2,3-BPG. No significant correlation was shown between the haemoglobin concentration and the 2,3-BPG/Hb4 ratio before dialysis (p=0.414). The pH showed a significant positive correlation with the 2,3-BPG/Hb4 ratio before dialysis, whereas the arterial pO2 and the 2,3-BPG/Hb4 ratio before dialysis were insignificantly negatively correlated. The concentrations of calcium, phosphate, creatinine, urea and albumin did not correlate significantly with the change in 2,3-BPG/Hb4-ratio after 1 h. The 2,3-BPG/Hb4 ratio (p=0.03) sampled just before dialysis correlated significantly and positively with the total weekly dosage of erythropoietin given to the patients.     

The i-STAT analyzer. A new, hand-held device for the bedside determination of hematocrit, blood gases, and electrolytes

Exact and quick measurements of basic laboratory parameters are important in selected patients in the perioperative period. Depending on the capabilities of a hospital's central laboratory, the anaesthesiologist may only obtain such laboratory tests after unacceptable delays. This problem may be overcome by a new bedside measurement device that has become available from i-STAT Corporation, Princeton, USA. The hand-held, battery-driven analyser accepts blood specimens that are injected into a disposable cartridge (EG7+) and measures acidity, blood gas tensions, haematocrit, and electrolytes. The aim of this study was to determine the accuracy of such measurements by comparing them with measurements obtained by conventional laboratory test methods. METHODS: Heparinised arterial blood specimens were collected in duplicate from 49 surgical patients. Measurements of ionised calcium (Ca), sodium (Na), potassium (K), pH, pCO2, pO2, base excess (BE), haematocrit (Hct), and haemoglobin (Hb) obtained by the i-STAT analyser were compared with measurements from the calibrated analysers ABL 615 and EML 100 (Radiometer, Copenhagen). Because the i-STAT analyser calculates the Hb concentration from a conductometrically measured Hct, 19 blood specimens were centrifuged in order to compare test results with conventionally obtained Hct and Hb values. As the Hct test sensitivity with the i-STAT changes with diluted blood due to its low albumin concentration, Hct and Hb measurements during cardio-pulmonary bypass (CPB) must be corrected by activating an analyser-implemented correction algorithm (Hct/CPB and Hb/CPB). Correlation analysis was performed between conventional measurements and i-STAT values (Ca, Na, K, Hct, pCO2, pO2), between values that the i-STAT analyser derives (Hb, HCO3, BE) and conventionally obtained results, and between normal and CPB-corrected Hct and Hb values. Accuracy was judged according to the national quality standard, which requires test results to lie within the 95% confidence interval of conventional tests. RESULTS: Each blood specimen was analysed: erroneous results or technical failures did not occur. Measurement of one set of i-STAT values required 2.5 min. Correlation coefficients (r) between conventional and i-STAT results were: 0.85 for CA, 1.0 for K; 0.86 for Na; 0.99 for pH; 0.98 for pCO2; 0.99 for pO2; 0.93 for HCO3; 0.93 for BE; 0.46 for Hb values not corrected for CPB and 0.95 for CPB-corrected Hb; and 0.74 for Hct values not corrected for CPB and 0.98 for CPB-corrected Hct. The correlation coefficient for Hct between centrifuged and CPB-uncorrected i-STAT values was 0.81 and that for CPB-corrected values was 0.98. National accuracy requirements were not met for tests of: Ca (by 0.02 mmol/l); pH (by 0.01); pO2 including hyperoxic values (by 26.7 mmHg, but were met for pO2 values < 200 mmHg); Hb (by 1.6 g/dl); Hb/CPB (by 0.8 g/dl); and Hct (by 6.5%, but were met for Hct/CPB values). All other tests fulfilled the required standards. CONCLUSION: This analyser is easy to use, reliable, and portable, and therefore suitable for the operating room, for analyses during emergencies, on peripheral wards, for preclinical screening, or at times when availability of lab tests is time-consuming or limited. The test accuracy for electrolytes, blood gases, and Hb is high enough to justify routine use of the i-STAT analyser in clinical practice. That the nationally required quality standards for Ca, pH, and Hb were not met is not of importance because the measured deviation was too small to have clinical relevance. When analysing diluted blood with a low Hct and low oncotic pressure, it is important to activate the analyser's correction algorithm "CPB", because the obtained results will then comply with the required accuracy.     

P-selectin blockade is beneficial after uncontrolled hemorrhagic shock

OBJECTIVE: Increased intra-abdominal pressure (IAP) compromises cardiopulmonary function and visceral perfusion. Our goal was to characterize acute changes in these subsystems associated with operative abdominal decompression. PATIENT POPULATION: A series of 11 consecutive injured patients monitored with a pulmonary artery catheter and nasogastric tonometer in whom operative decompression was performed. Indications for decompression included oliguria or progressive acidosis despite aggressive resuscitation in the presence of elevated IAP (>25 mm Hg). MAIN OUTCOME MEASURES: Studied hemodynamic variables included pulmonary artery occlusion pressure (PAOP), right ventricular end-diastolic volume index (RVEDVI), and cardiac index (CI). Pulmonary variables included shunt fraction (Qs/Qt) and dynamic compliance (Cdyn). Visceral perfusion was assessed using hourly urine output 4 hours before and after decompression (UOP) and gastric intramucosal pH (pHi). Mean values before and after decompression were compared using the paired t test. Linear regression and Fisher's z transformation were used to evaluate the relationships between RVEDVI, PAOP, CI, and IAP. IAP was transduced via bladder pressures. Significance was defined as p < 0.05. Data are expressed as means+/-SD. RESULTS: IAP decreased with decompression (49+/-11 to 19+/-6.8 mm Hg; p < 0.0001). RVEDVI improved independent of CI and correlated better (p < 0.01) with CI (r =0.49, p=0.04) than PAOP did (r=-0.36, p=0.09). PAOP correlated significantly with IAP (r=0.45, p=0.04). Decompression resulted in significant improvements in Qs/Qt, Cdyn, UOP, and pHi. CONCLUSION: Abdominal decompression in patients with increased IAP improves preload, pulmonary function, and visceral perfusion. Elevated IAP has important effects on PAOP, which makes the PAOP an unreliable index of preload in these patients.     

Noninvasive determination of cardiac output in patients with severe airflow limitation

The noninvasive measurement of cardiac output (Q) by the Indirect Fick CO2-rebreathing technique requires mixed venous P CO2 (P CO2) to be determined by the rebreathing maneuver, and Pa CO2 to be estimated from end-tidal P CO2 (PET CO2). Previous work has suggested that although P CO2 can be determined, Pa CO2 cannot be accurately estimated in patients with significant airflow limitation. Nineteen patients with cystic fibrosis who had severe airflow limitation (%FEV1, 29.3 +/- 7.12 SD) were studied during steady-state exercise at 50% of their measured maximal work capacity. Estimated Pa CO2 was slightly lower than Pa CO2 measured from blood samples obtained from an indwelling arterial catheter (measured: 45.2 +/- 4.92; estimate: 42.7 +/- 5.68 mm Hg). To calculate arterial blood content, the values derived from Pa CO2, pH, hemoglobin (Hb), and O2 saturation were compared with those derived from PET CO2 and O2 saturation, where (1) pH was assumed to be 7.40 and Hb was measured, and (2) pH was assumed to be 7.40 and Hb was assumed to be 15 g/dl (measured mean pH, 7.34; Hb, 14.4 g/dl). No difference in arterial CO2 content was seen between the three methods (measured: 47.53 +/- 5.17; estimate 1: 49.57 +/- 6.58; estimate 2: 49.12 +/- 6.61 ml/100 ml). As pH and Hb can also affect mixed venous CO2 content, the effect on Q was also assessed. Both estimates fit closely with measured Q (r2=0.77 and 0.76), with intercepts not different from zero and slopes not different from 1, and coefficients of variation of 13.5 and 14.6%. When viewed with regard to the confidence intervals for Q as a function of O2 consumption, Q was altered to a minor extent. We conclude that the use of PET CO2 to estimate Pa CO2 can give reasonable values for Q determined noninvasively in patients with severe airflow limitation.     

Effects of selective nitric oxide synthase inhibitor in sheep with endotoxic shock

OBJECTIVE: To investigate the effects of S-methylisothiourea sulfate (SMT), a selective inducible nitric oxide synthase (iNOS) inhibitor, on hyperdynamic endotoxic shock sheep. METHODS: Endotoxic shock was induced by Escherichia coli endotoxin in both control (n = 8) and SMT groups (n = 8). SMT was given intravenously. Hemodynamic data, oxygen delivery derived parameters and intramucosal pH (pHi) were measured. RESULTS: The control group had a hyperdynamic state, similar to that of human septic shock. In the SMT group, blood pressure was maintained at baseline, and cardiac index (CI) was lower than that in the control group (P < 0.05). Oxygen extraction ratio (O2 ext) was increased up to 40% +/- 5% and was much higher than that of the control group (P < 0.01). Pulmonary artery pressure (PAP) was higher than that of the control group (P < 0.01), and pHi decreased gradually similarly to the control group. CONCLUSION: SMT restored the blood pressure and increased O2 extespecially in the gut, but decreased CI and oxygen delivery and increased PAP. So over inhibition of iNOS should be cautiously considered.     

Subcutaneous and gut tissue perfusion and oxygenation changes as related to oxygen transport in experimental peritonitis

Peritonitis and septic shock may lead to tissue hypoxia, but this risk is not identical in all organ systems. This study was undertaken to measure changes in tissue oxygenation and perfusion in the gut wall and subcutaneous tissue, respectively, and to examine their relation to oxygen delivery and consumption. Twelve pigs were anesthesized and mechanically ventilated. An ultrasonic flow probe was placed around the superior mesenteric artery for registration of blood flow. A mesenteric vein was cannulated for blood sampling. For calculation of gut intramural pH (pHi), a Silastic balloon (Tonomitor) was placed in the lumen of the midileum. pHi was calculated from tonometrically measured PCO2 and arterial bicarbonate concentration. The subcutaneous PO2 was measured by means of an oxygen-permeable Silastic tube implanted in the subcutis of the abdominal wall. Oxygen delivery (DO2) and consumption (VO2) were determined for the gut as well as for the whole body. In six randomly allocated animals, peritonitis was induced after a stabilization period of at least 1 hr, by instillation of autologous faeces into the abdominal cavity, while the other six animals served as controls. The animals were then followed for 5 hr. pHi remained stable in the control group, whereas a drop from 7.37 to 7.02 took place in the peritonitis group. In the test group, subcutaneous oxygen tension (PscO2) already began to fall 1 hr after the induction of peritonitis, and gained the minimum at the end of the study. In peritonitis, a moderate correlation was seen between pHi and DO2 (r = 0.51 +/- 0.16); no statistical difference was noted if pHi was correlated to gut DO2 (r = 0.56 +/- 0.18).(ABSTRACT TRUNCATED AT 250 WORDS)     

Hepatosplanchnic and peripheral tissue oxygenation during treatment of hemorrhagic shock: the effects of pentoxifylline administration

OBJECTIVE: To evaluate the effects of pentoxifylline (PF) administration on liver, gut, and peripheral oxygenation during crystalloid resuscitation of hemorrhagic shock. SUMMARY BACKGROUND DATA: Hypoperfusion of the hepatosplanchnic vascular bed and hypoxia of vital organs may be prolonged despite adequate therapy of hemorrhagic shock. Vasoconstriction, leukostasis, platelet aggregation, and red blood cell plugging could be the underlying causes. PF has been shown to counteract these effects, but its effects in a large animal shock model have been less studied. METHODS: Thirteen anesthetized piglets (mean weight 19.6 kg) were bled steadily to a mean arterial pressure (MAP) of 40 to 50 mmHg and a 70% reduction in cardiac output during 1 hour. These levels were maintained for an additional hour. The animals were resuscitated with acetated Ringer's solution according to MAP and cardiac output values and followed for 80 minutes (total 3 hours and 20 minutes). Seven piglets were given PF boluses (12.5 mg/kg) and infusion (0.2 mg/kg x min), and the rest (n = 6) served as controls. Hemodynamic and systemic oxygen transport variables were recorded. Liver parenchymal and peripheral tissue (subcutaneous, transcutaneous, conjunctival) oxygen tensions (PO2) were measured continuously with polarographic electrodes. Jejunal intramucosal pH (pHi) was calculated every hour by the luminal PCO2, obtained with a balloon tonometer, and arterial bicarbonate concentration. RESULTS: Cardiac output decreased by a mean of 76% during shock and was restored during resuscitation in both groups. MAP decreased from 110 to 40 mmHg but remained at 70 to 80 mmHg during resuscitation in both groups despite remarkable volume load (2.6 ml/min per kg). Liver parenchymal PO2 decreased from 29+/-1 to 15+/-1 mmHg during shock and increased to 36+/-2 mmHg in the PF group, whereas in control group it remained at 26 mmHg. The difference between groups was significant, but at the end of follow-up the liver PO2 decreased to 21 mmHg in both groups. Gut pHi, peripheral tissue oxygen tensions, and the plasma adrenaline and noradrenaline concentrations did not differ between the groups. CONCLUSIONS: Pentoxifylline improved specifically, although only transiently, liver tissue oxygenation. Perhaps the microvascular abnormalities after resuscitation of hemorrhagic shock are more prominent in the hepatic vascular bed, rendering PF specifically effective in that area. The lack of any effect of PF on gut and peripheral tissue oxygenation may have resulted from the persistent vasoconstriction and inadequate restoration of blood volume with crystalloid solution.     

Role of calciotrophic hormones in calcium mobilization of lactation

In two consecutive studies (Study A and Study B), we evaluated the effects of increasing doses of HBOC-201, a bovine hemoglobin-based oxygen carrier, on hemodynamics and oxygen transport in patients undergoing preoperative hemodilution for elective abdominal aortic surgery. After the induction of anesthesia and the exchange of 1 L of blood for 1 L of lactated Ringer's solution, 24 patients (12 in each study) were randomly assigned to receive, within 30 min, a predetermined volume of either HBOC-201 or 6% hydroxyethyl starch (Study A 6.9 mL/kg; Study B 9.2 mL/kg). Monitored variables included systemic and pulmonary arterial pressures, arterial and mixed venous blood gases, and calculations of cardiac index (CI), systemic (SVRI) and pulmonary (PVRI) vascular resistance indices, oxygen delivery index (DO2I), oxygen consumption index (VO2I), and oxygen extraction ratio (O2ER). In both studies, the infusion of HBOC-201 was associated with increases in SVRI (Study A 121%; Study B 71%) and PVRI (Study A 70%; Study B 53%) and with a decrease in CI (29% both studies). Hemodilution with HBOC-201 maintained the arterial oxygen content at levels higher than hemodilution with hydroxyethyl starch, but the advantage of a greater oxygen-carrying capacity was offset by the increase in SVRI, with a resulting net decrease in both CI and DO2I (Study A 30%; Study B 28%); VO2I was maintained by increased O2ER. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch. Implications: Bovine hemoglobin in doses ranging between 55 and 97 g of hemoglobin increased vascular resistance and decreased cardiac output in anesthetized surgical patients. In terms of hemodynamics and oxygen transport, hemodilution with bovine hemoglobin in these doses provided no apparent benefit over hemodilution with hydroxyethyl starch.     

The presurgical management with erythrocytapheresis of a patient with a high-oxygen-affinity, unstable Hb variant (Hb Bryn Mawr)

BACKGROUND: Hemoglobin (Hb) Bryn Mawr is an unstable Hb variant resulting in congenital hemolytic anemia. This variant Hb also has an increased affinity for oxygen. The perioperative transfusion management of this disorder is described, and the first genomic analysis of this Hb variant is given. CASE REPORT: An 11-year-old boy, heterozygous for Hb Bryn Mawr, was referred for cholecystectomy. Sequence analysis of genomic DNA confirmed that the patients was heterozygous for a T-->C transition in the codon for amino acid 85, causing a substitution of serine for phenylalanine in the beta-globin chain. On the basis of whole-blood O2 dissociation studies, projected tissue O2 delivery would have been suboptimal during general anesthesia; therefore, a partial red cell exchange transfusion was performed to lower variant Hb and prevent tissue hypoxia during surgery. The red cell mass to be exchanged (50%) was determined from the calculated increase in O2 delivery capacity required to maintain an O2 extraction of 4 to 5 mL of O2 per dL of whole blood. The p50 of whole blood from the patients immediately after the exchange transfusion was 16.0 torr. At the time of surgery, the p50 was normal (25.9 torr). The patient's whole blood 2,3 DPG levels were 4.70 mmol per mL of red cells (before transfusion) (normal range = 4.8 +/- 0.3 mmol/mL red cells), 4.07 mmol per mL of red cells (immediately after transfusion), and 4.55 mmol per mL of red cells (48 hours after transfusion). CONCLUSION: This patient with Hb Bryn Mawr was prepared for surgery with a partial exchange transfusion to prevent tissue hypoxia during anesthesia. Decreased 2,3 DPG levels immediately after transfusion resulted in increased O2 affinity of whole blood; however, 48 hours after exchange transfusion, a normal p50 (due to both removal of variant Hb and regeneration of 2,3, DPG) was observed. Partial exchange transfusion is useful in the preoperative management of patients with Hb variants characterized by increased O2 affinity.     

Evidence for essential arginine residues at the active sites of maize branching enzymes

Alignment of 23 branching enzyme (BE) amino acid sequences from various species showed conservation of two arginine residues. Phenylglyoxal (PGO) was used to investigate the involvement of arginine residues of maize BEI and BEII in catalysis. BE was significantly inactivated by PGO in triethanolamine buffer at pH 8.5. The inactivation followed a time- and concentration-dependent manner and showed pseudo first-order kinetics. Slopes of 0.73 (BEI) and 1.05 (BEII) were obtained from double log plots of the observed rates of inactivation against the concentrations of PGO, suggesting that loss of BE activity results from as few as one arginine residue modified by PGO. BE inactivation was positively correlated with [14C]PGO incorporation into BE protein and was considerably protected by amylose and/or amylopectin, suggesting that the modified arginine residue may be involved in substrate binding or located near the substrate-binding sites of maize branching enzymes I and II.     

Effects of loprinone hydrochloride on hemodynamics and respiratory oxygenation in patients after cardiac surgery

Loprinone hydrochloride (Lop), a phosphodiesterase fraction III inhibitor and positive inotrope, was recently released in Japan. We evaluated its dose-related effects on hemodynamics and oxygenation as as well as on plasma levels of Lop in ten patients after cardiac surgery. Immediately after admission to the intensive care unit, baseline hemodynamics and arterial blood gas data were obtained; patients with inotropic support, were given 0.1, 0.2, 0.3 microgram.kg-1.min-1.lop over 1 hour incrementally, and additional data were obtained. CI increased significantly from baseline (2.1 +/- 0.3 l.min-1.m-2) to 3.2 +/- 0.8 at 0.3 microgram.kg-1.min-1. Systemic vascular resistance decreased significantly from baseline (2853 +/- 439 dynes.sec.cm-5.m-2) to 1554 +/- 440 at 0.3 micrograms. kg-1.min-1, and mean arterial pressure also decreased significantly from baseline. There were no significant changes in heart rate (HR), central venous pressure (CVP), pulmonary artery occlusion pressure (PAOP), or PaO2.FIO2(-1) in patients over the period evaluated. Plasma levels of Lop rapidly increased to 27.8 ng.ml-1 (effective level; 20 ng.ml-1) at 0.3 microgram.kg-1.min-1. In this study, Lop was shown to effectively increase CI in patients after cardiac surgery with no significant changes in HR, CVP, PAOP or PaO2/FIO2. Thus, Lop has a beneficial effect in the treatment of patients with low cardiac output immediately after cardiac surgery.