Effect of ranitidine on gastric intramucosal pH in critically ill patients

Objective: To determine whether ranitidine a) increases the values of gastric intramucosal pH (pHi) in critically ill patients, as determined by tonometry; b) reduces the variability of these measurements. Design: Prospective, double blind, randomized, placebo-controlled study. Setting: General Intensive Care Unit of a teaching hospital. Patients: Twenty-five critically ill, mechanically ventilated patients requiring arterial catheter and nasogastric tube. Interventions: Tonometer placement; blind, random administration of intravenous ranitidine (50 mg) or placebo. Measurements and main results: Tonometer saline PCO₂ (PCO₂i), arterial blood gases, gastric juice pH and pHi were determined immediately before, and 2, 4, 6 and 8 h after, ranitidine (12 patients) or placebo (13 patients). Ranitidine significantly increased gastric juice pH, but did not affect PCO₂i or pHi; pHi was 7.34 ± 0.14 before ranitidine, and 7.30 ± 0.12, 7.31 ± 0.11, 7.31 ± 0.14 and 7.31 ± 0.12 – 2, 4, 6 and 8 h, respectively, after ranitidine administration (p = 0.55). Ranitidine did not modify the coefficients of variation of PCO₂i or pHi, either. No significant changes in gastric juice pH, PCO₂i or pHi were observed in the placebo group. Conclusions: In critically ill patients, ranitidine has no effect on pHi values, and does not increase the reproducibility of pHi measurements. Received: 24 October 1996 Accepted: 22 October 1997     

Effect of sucralfate on gastric intramucosal pH in critically ill patients

Objective: To determine whether sucralfate administration affects the tonometric measurement of gastric intramucosal pH (pHi). Design: Non-randomized observational study. Setting: General intensive care unit of a teaching hospital. Patients: Twenty critically ill, mechanically ventilated, consecutively admitted patients requiring an arterial catheter and nasogastric tube. Interventions: Tonometer placement and sucralfate administration. Measurements and main results: We simultaneously determined tonometer saline PCO₂ (PCO₂i), arterial blood gases, pH of gastric juice and pHi. These parameters were evaluated immediately before sucralfate administration, and 2 h and 4 h after. We did not detect any change in either PCO₂i or pHi after sucralfate administration (PCO₂i: basal 6.4 ± 1.7, 2 h 6.3 ± 1.7, 4 h 6.3 ± 1.7; pHi: basal 7.35 ± 0.13, 2 h 7.36 ± 0.12, 4 h 7.36 ± 0.12). Conclusions: Sucralfate does not affect the tonometric measurement of PCO₂i and pHi. Received: 21 August 1996 Accepted: 18 April 1997     

Effect of nasogastric suction and ranitidine on the calculated gastric intramucosal pH

Objective To study the effect of nasogastric suction and ranitidine on the determination of gastric intramucosal pH (pH_i).Design Prospective study.Setting Clinical research unit at a university hospital intensive care department.Subjects 12 healthy volunteers.Interventions After a 2-h measurement control period a tonometer was connected to nasogastric suction for 2 h, and thereafter ranitidine was given intravenously and gastric pH_i measured.Measurements and results During each 2-h measurement period gastric PCO₂, gastric pH_i, and pH gap were determined every 30 min. Luminal pH was measured after insertion of tonometer and at the end of each study period. Neither nasogastric suction nor ranitidine had an effect on the coefficient of variation for either gastric PCO₂ or pH_i. Compared to control and nasogastric suction periods, after ranitidine mean gastric pH_i was higher (control 7.22±0.08; nasogastric suction 7.23±0.07; after ranitidine 7.31±0.06,p<0.001) mean gastric PCO₂ lower (control 6.4±1.3; nasogastric suction 6.5±1.3; after ranitidine 5.3±0.9,p<0.001) and pH gap lower (control 0.18±0.08; nasogastric suction 0.17±0.05; after ranitidine 0.09±0.06,p<0.01). Luminal pH increased after ranitidine in each subject.Conclusions H₂ blockers have no effect on the reproducibility of gastric pH_i measurements, but the use of H₂ blockers modifies the normal values for gastric pH_i in healthy subjects.This study was supported, in part, by the senior clinical researcher's grant 1945/3015/92 from the Academy of Finland to Dr. Takala.     

机械通气患者早期肠内营养与胃黏膜pH值监测的临床应用

目的 观察早期肠内营养及胃黏膜pH值(pHi)监测对重症监护病房(ICU)中非胃肠道外伤或手术需机械通气患者的疗效.方法 通过连续监测40例患者术后7 d内pHi的变化,并根据生命体征和肠鸣音的恢复情况分别于术后12～72 h内(早期)给予肠内营养(25例)和静脉营养(15例),比较两组7 d内脱机成功率及机械通气时间.结果 肠内营养组7 d内脱机成功率明显高于静脉营养组[76%(19/25)比40%(6/15),P<0.05],机械通气时间则明显短于静脉营养组[(4.30±0.01)d比(8.22±0.02)d,P<0.05];肠内营养组术后7 d pHi较1 d时增加(7.39±0.03比7.28±0.01,P<0.05),且明显高于静脉营养组(7.30±0.02,P<0.05).此外,肠内营养组较静脉营养组恢复排气时间明显缩短[(47.08±8.33)h比(67.03±8.03)h,P<0.05].结论 pHi监测是反映危重病患者胃肠黏膜血液灌注及氧合状态的敏感指标;早期实施肠内营养可以改善患者胃肠黏膜血液灌注,从而有效防止肠道细菌移位的发生,提高脱机成功率并缩短时间;只要胃肠道功能正常,应尽早实施肠内营养支持.     

兔内毒素血症时胃黏膜内pH的改变

目的　研究兔内毒素血症时胃黏膜内pH (pHi)的变化。方法　选用雄性家兔 10只 ,随机分成 2组。组Ⅰ (n =5 )为正常对照组静注生理盐水 :组Ⅱ (n =5 )实验前 2 4h静注大肠杆菌内毒素 [EColiLPS ;3μg/ (kg·ml) ],并进行大剂量LPS (10 0 μg/kg ;5 0ml/ 4h)滴注。监测动脉血压 (MAP)。应用胃肠张力仪测得胃黏膜局部CO2 张力 ,计算胃黏膜内pH (pHi)。留取血浆测定NO水平。实验观察大剂量LPS滴注前 (T0 )、后 2h (T2h)和 10h (T1 0h)上述参数变化。静注 10 %KCl 5ml处死后取空肠作HE染色观察。结果　MAP在组Ⅰ无变化 ,组Ⅱ在T1 0h 时血压明显下降 ;血浆NO水平在组Ⅰ无变化 ,组Ⅱ在T0 、T2h 和T1 0h各点均较组Ⅰ显著升高 ,并呈进行性增高。组Ⅰ动脉血pH和pHi值无变化 ,组Ⅱ在T2h和T1 0h均较组Ⅰ为低 (P <0 0 5 )。空肠病理形态学检查组Ⅱ绒毛显著肿胀 ,基底膜增厚。结论　小剂量LPS即可导致血浆NO水平升高 ;大剂量LPS给入后 ,动脉血pH和pHi下降早于动脉血压改变 ,且pHi下降与空肠绒毛的病理损害变化一致。     

Low intramucosal pH is associated with failure to acidify the gastric lumen in response to pentagastrin

Objective To determine if low gastric intramucosal pH is associated with impaired secretion of gastric acid after pentagastrin stimulation.Design Prospective study.Setting Intensive care unit of a university teaching hospital.Patients 20 patients requiring mechanical ventilation.Interventions All patients with a gastric luminal pH>4 were given pentagastrin 6 g/kg s.c. to stimulate gastric acid secretion and the response assessed by further measurements of gastric luminal pH.Measurements and results Gastric intramucosal pH (pHi) and luminal pH (pH_L) were measured. Patients were divided into two groups on the basis of a low or normal pHi (A value of 7.35 was taken as the lower limit of normal). Patients (n=6) with normal pHi (7.40±0.05 [mean±SD]) and a luminal pH>4 (5.65±1.25) all had a decrease in pH_L in response to pentagastrin (decrease in pH_L 4.02±1.52). Of the patients (n=7) with low pHi (7.2±0.13) and a pH_L>4 (6.51±0.48) only one responded to pentagastrin (decrase in pH_L for this group 0.93±1.86). Patients with a pH_L<4 (2.4±0.71) were not given pentagastrin (n=7).Conclusion Some critically ill patients with low gastric intramucosal pH appear to have an impaired ability to acidify the gastric lumen in response to pentagastrin.     

The effects of prostacyclin on gastric intramucosal pH in patients with septic shock

Objective To investigate whether infusing prostacyclin (PGI₂) in patients with septic shock improves splanchnic oxygenation as assessed by gastric intramucosal pH (pHi).Design Interventional clinical study.Setting Surgical ICU in a university hospital.Patients 16 consecutive patients with septic shock according to the criteria of the ACCP/SCCM consensus conference all requiring norepinephrine to maintain arterial blood pressure.Interventions All patients received PGI₂ (10 ng/kg·min) after no further increase in oxygen delivery could be obtained by volume expansion, red cell transfusion and dobutamine infusion. The results were compared with those before and after conventional resuscitation. The patients received continuous PGI₂ infusion for 3–32 days.Measurements and results O₂ uptake was measured directly in the respiratory gases, pHi was determined by tonometry. Baseline O₂ delivery, O₂ uptake and pHi were 466±122 ml/min·m², 158±38 ml/min·m², and 7.29±0.09, respectively. While O₂ uptake remained unchanged, infusing PGI₂ increased O₂ delivery (from 610±140 to 682±155 ml/min·m²,p<0.01) and pHi (from 7.32±0.09 to 7.38±0.08,p<0.001) beyond the values obtained by conventional resuscitation. While 9 of 11 patients with final pHi>7.35 survived, all patients with final pHi<7.35 died (p<0.01).Conclusions Infusing PGI₂ in patients with septic shock increases pHi probably by enhancing blood flow to the splanchnic bed and thereby improves splanchnic oxygenation even when conventional resuscitation goals have been achieved.Presented in part at the 13th International Symposium on Intensive Care and Emergency Medicine, Brussels, March 1993     

脑出血患者胃粘膜pH值与氧输送变化的临床意义

目的初步探讨脑出血患者胃粘膜ｐＨ值（ｐＨｉ）及氧输送（ＤＯ２）改变与急性应激性胃粘膜病变（ＡＳＧＬ）的关系。方法对７例脑出血患者进行胃粘膜ｐＨ、ＤＯ２和胃潜血测定。结果成活组４例中,在监测开始时ｐＨｉ与ＤＯ２都在正常范围内,而死亡３例中ｐＨｉ都明显减低,但ＤＯ２减低不明显。随着治疗,死亡组ｐＨｉ明显下降,与成活组２４小时、４８小时相比,差异显著（Ｐ＜００１）;成活组ＤＯ２逐渐下降,而死亡组ＤＯ２有增高趋势。有４例病人出现了ＡＳＧＬ,死亡组３例均出现了严重的消化道出血。结论监测ｐＨｉ对判断组织氧合及预后有重要意义,与ＤＯ２结合起来对治疗有具体的指导意义。但因ｐＨｉ与ＤＯ２不完全依赖,在部分病人中,仅以提高ＤＯ２为治疗原则是不够的。     

Validity of gastric intramucosal pH (pHi) for circulatory evaluation in pediatric patients

Objective.To determine if the measurement of gastricintramucosal pH (pHi) is useful for evaluation of circulatory status ofcritically ill pediatric patients. Design.Prospective clinicalstudy. Setting.General intensive care unit in a universityhospital. Patients.Seven pediatric patients (mean age: 2 y.o.);six post-cardiac surgery, one receiving barbiturate therapy.Interventions.Tonometric catheters were placed via nasogastricapproach. pHi was measured after confirmation of the catheter positionby X-ray. Measurements and main results.Saturation of venousblood oxygen (SvO₂), arterial keton body ratio (AKBR), serumlactate level and pHi were evaluated simultaneously. No patientssurvived with pHi below 7.22; pHi above 7.11 significantly correlatedwith SvO₂ values (r= 0.814, p< 0.001);pHi below 7.11 did not show any significant correlation withSvO₂. Whereas SvO₂ values of under 40% weredistributed in the pHi range from 7.11 to 7.19, pHi below 7.11 occurredwhen SvO₂ values were more than 40%. AKBR and serumlactate level did not correlate with pHi. Conclusion.pHi can bea useful parameter for evaluating the circulatory status of criticallyill pediatric patients; it allows reliable evaluation of splanchnic andperipheral perfusion.     

脓毒性休克早期胃肠黏膜pH变化与其预后相关性研究

目的：探讨脓毒性休克早期胃肠黏膜pH变化与其预后相关性。方法：脓毒性休克患儿44例根据转归不同分为3组：存活组28例;休克死亡组12例（于入院24h内死亡,死亡原因为不可逆性休克）;多器官功能障碍综合征死亡组4例（治疗24h以上,死亡原因为多脏器功能衰竭）。采用胃管法监测其胃肠黏膜pH变化,同时进行生命体征监测和小儿危重病例评分,对其预后相关因素进行分析。结果：存活组与死亡组比较,初次胃肠黏膜pH变化差异有统计学意义（P〈0．01）,经治疗存活组胃肠黏膜PH明显升高,治疗前、后差异有统计学意义（P〈C0．05）,而死亡组治疗前、后差异无统计学意义（P〉0．05）。结论：胃肠黏膜PH变化可直接反映脓毒性休克严重程度,指导临床进行早期干预治疗并改善预后。     

胃黏膜pH监测对重度急性颅脑外伤患者的临床意义

目的探讨重度急性颅脑外伤患者胃黏膜pH值(pHi)及其衍生指标PgapCO2和pHgap的变化与重度急性颅脑外伤患者脑外并发症(应激性溃疡出血和多器官功能障碍综合征)及近期预后之间的关系。方法队列研究2002-11～2003-12收治的重度急性颅脑外伤患者共41例,入院予以常规治疗。用自动空气张力计法每小时测一次PgCO2,共测24h。入院当时及入院后8、16、24h测动脉血气,应用S/5监护仪自动计算胃pHi及其衍生指标PgapCO2、pHgap。将一次或一次以上胃pHi值<732者归为降低组,≥732者归为正常组。根据1周内是否存活,分为存活组和死亡组。每日观察胃液隐血。连续7d每日进行SOFA评价和MOF评分。结果胃pHi正常组23例,降低组18例。死亡12例。胃pHi降低组与正常组1周内病死率、胃液隐血阳性发生率、MODS发生率、SOFA评分和MOF评分的差别有统计意义(P<001或P<005)。存活组与死亡组的胃液隐血阳性发生率和MODS发生率的差别有统计意义(P<005和P<001)。存活组与死亡组入院时PgapCO2差别有统计意义(P<001)。入院24h两组PgCO2、PgapCO2、pHi和pHgap差别均有统计意义(P<005或P<001)。结论入院24h内胃pHi及其衍生指标PgapCO2、pHgap的异常对重度急性颅脑外伤的脑外并发症及其近期预后有预警作用。     

失血性休克时胃粘膜内pH与组织氧合监测的实验研究

目的 进一步探讨粘膜内pH与值肠粘膜组织氧合的关系。方法 以失血性休克大鼠为模型,根据胃内PCO2和同时测得的动脉血HCO3^-浓度,通过Henderson-Hasselbalch公式间接测定胃粘膜内pH(pHi),同时测定动脉血,混合静脉血,门静脉乳酸（Lacp)及动脉血,混合静脉血气分析。结果 失血性休克时,pHi与门静脉乳酸（Lacp)显降低,两呈线性关系（r=-0.88),pHi的降低不仅与胃肠粘膜的氧合障碍有关,同时还与全身组织氧合不足有关,失血性休克时,pHi的降低与胃肠粘膜的病理性损害一致。结论 pHi的变化可早期反映肠道及全身组织氧合情况,可作为重症监护的一个重要指标。     

Ranitidine or dobutamine alone or combined has no effect on gastric intramucosal-arterial PCO2 difference after cardiac surgery

Objective: To test the hypothesis that ranitidine, either alone or in combination with dobutamine, modifies the gastric intramucosal-arterial PCO₂ difference.¶Design: Full factorial design (double-blinded for ranitidine).¶Setting: Intensive Care Unit of a university hospital.¶Patients: Sixty-four haemodynamically stable coronary artery bypass surgery patients.¶Interventions: Ranitidine (150 mg preoperatively per os and 50 mg intravenously postoperatively) and dobutamine (4 μ g · kg^–1· min^–1 for 3 h postoperatively) were administered in four randomised groups of patients: preoperative and postoperative ranitidine, either alone (n = 15) or in combination with dobutamine (n = 17), dobutamine alone (n = 15) or neither ranitidine nor dobutamine (n = 17).¶Measurements and results: Gastric intramucosal-arterial PCO₂ difference was measured during the first 5 postoperative hours. No differences in the postoperative pattern of gastric intramucosal-arterial PCO₂ difference were found among the groups.¶Conclusions: Ranitidine and dobutamine have no effect on the gastric tonometry results on intramucosal-arterial PCO₂ difference after uncomplicated cardiac surgery. Hence, the routine use of H₂-antagonists for gastrointestinal tonometry is not warranted. Our results must be limited to results obtained by tonometry; they do not allow any conclusions on the effects of these drugs on splanchnic blood flow or its distribution.     

Assessment of the perfusion in peripheral tissue beds by subcutaneous oximetry and gastric intramucosal pH-metry in elective colorectal surgery

Gastric intramucosal pH (pH_i) and subcutaneous oxygen tension (P_scO₂) were compared with traditional perfusion parameters in patients undergoing elective colorectal surgery and were related to clinical outcome. Ten patients were studied per- and postoperatively and tissue oximetry studies were also performed in a group of 10 healthy volunteers. The response of P_scO₂ to oxygen breathing proved to be the most sensitive predictor of clinical outcome. Of the 10 patients 8 failed to respond to an O₂ challenge, while all 10 volunteers in the control group did so. Out of those 8 patients 6 presented with mainly infectious complications while only 3 had an inadequate perioperative urine output and none presented with signs of arterial or of gastric intramural acidosis. The present study suggests a possible relationship between clinical outcome and oxymetric signs of tissue hypoperfusion after O₂ challenge in surgical patients, even in the presence of an adequate urine output and a normal gastric wall pH.     

Predictive value of interleukin 6 (IL-6), interleukin 8 (IL-8) and gastric intramucosal pH (pH-i) in major abdominal surgery

Objective: To study plasma concentrations of interleukin 6 (IL-6) and interleukin 8 (IL-8) in patients with splanchnic hypoxia, as documented by gastric intramucosal measurements (pH-i), during major abdominal surgery and the relationship between IL-6 and IL-8 concentrations and postoperative complications as well as clinical outcome. Design: A prospective study. Patients: Twelve patients scheduled for major abdominal surgery with no evidence of coexisting infectious disease. Results: Six out of seven samples from patients with postoperative complications showed intraoperative pH-i levels lower than 7.32 and IL-6 levels higher than 300 pg/ml. Seven out of nine samples from patients without complications showed pH-i levels higher than 7.32 and IL-6 levels lower than 300 pg/ml. The difference in the pattern of distribution was statistically significant (p < 0.01). Only two out of seven samples of patients with postoperative complications showed intraoperative pH-i levels lower than 7.32 and IL-8 levels higher than 60 pg/ml. It was not possible to identify a clear distribution pattern of data points for IL-6 and IL-8 during the postoperative period. Conclusions: Intraoperative splanchnic ischemia, as documented by gastric intramucosal pH-i, is directly correlated to the increase of IL-6 plasma levels and to the incidence of postoperative complications, while IL-8 levels showed no correlation with surgical complications. Received: 4 June 1997 Accepted: 26 January 1998     

急性重症胰腺炎患者生长抑素干预前后pHi监测及其临床意义

目的 :探讨胃黏膜 p H值 (p Hi)在急性重症胰腺炎患者生长抑素干预前后的变化及其临床意义。方法 :按有无生长抑素 (施他宁 )干预将 4 6例急性重症胰腺炎患者分为生长抑素治疗组 (2 0例 )和无生长抑素治疗组 (对照组 ,2 6例 ) ,2组基础治疗相同。在治疗前、治疗后第 3日和第 7日用胃张力计导管法测定 2组患者p Hi,同时每日评价 2组患者器官功能 ,在患者器官功能衰竭最严重时测定 p Hi,比较 p Hi与器官功能衰竭的相关性。结果 :1生长抑素干预组患者并发器官功能衰竭的发生率显著低于对照组 (45 %比 5 8% ,P<0 .0 5 ) ;2治疗后第 7日生长抑素治疗组 p Hi值较对照组显著增高 (7.392± 0 .0 5 8比 7.335± 0 .10 1,P=0 .0 0 7) ;3p Hi值与功能衰竭器官数目呈显著负相关 (r=0 .5 92 ,P<0 .0 0 1)。结论 :生长抑素可降低急性重症胰腺炎患者器官功能衰竭的发生率 ,其作用机制可能与提高 p Hi、改善患者组织供氧有关     

急性重度有机磷农药中毒胃黏膜pH值监测的意义

目的：探讨胃黏膜内pH值（pHi）监测在急性重度有机磷农药中毒（ASOPP）中的应用及临床意义。方法：28例ASOPP患者在洗胃后立即经鼻插入TRIP－NGS导管测定pHi,以后每12小时监测1次;另以12例健康者为对照。结果：在ASOPP未并发急笥呼吸衰竭（ARF）时,患者的pHi就明显降低（P＜0.05）,而此时全身氧供指标－－动脉氧分压（PaO2)无明显改变（P＞0.05）;在ASOPP并发ARF时,患者的pHi比PaO2降低得更明显。结论：pHi监测对早期发现ASOPP患者局部组织缺氧及采取措施预防ARF与多脏器功能衰竭的发生具有重要临床指导意义。     

Gastric intramucosal pH and intraluminal PCO2 during weaning from mechanical ventilation

OBJECTIVE: To study the value of gastric intramucosal pH and gastric intraluminal PCO2 measurements to predict weaning outcome from mechanical ventilation. DESIGN: Prospective clinical study. SETTING: Intensive care medicine department of a university hospital. PATIENTS: Nineteen adult critically ill patients who were mechanically ventilated because of acute respiratory failure and were considered ready to be weaned. INTERVENTIONS: The patients were weaned with: synchronized intermittent mandatory ventilation plus positive end-expiratory pressure (SIMV+PEEP) or continuous positive airway pressure with pressure support ventilation (CPAP+PSV). A gastric tonometer was placed in all the patients. Tonometric, respiratory, and hemodynamic variables were measured during the weaning process. MEASUREMENTS: Hemodynamic variables, respiratory mechanics, pulmonary gas exchange, respiratory muscle force, spontaneous pattern of breathing, and the central control of breathing were recorded. Simultaneously, the intramucosal pH and gastric intraluminal PCO2 were measured. MAIN RESULTS: Eleven patients were successfully extubated and eight failed. The patients who failed showed higher values of mouth occlusion pressure, respiratory rate, and effective inspiratory impedance (mouth occlusion pressure/mean inspiratory flow). The intramucosal pH was initially 7.19 +/- 0.22 and decreased to 7.10 +/- 0.16 during the weaning process in patients who failed (p < .05). At the same time, the intramucosal pH showed a nonsignificant change from 7.36 +/- 0.07 to 7.32 +/- 0.07 in the patients who were successfully extubated. The intramucosal pH was statistically different when both groups were compared during the initial and the final evaluations (p < .05). For the initial evaluation, the sensitivity and specificity to predict weaning failure when the intramucosal pH was < or =7.30 were 0.88 (95% confidence interval [CI], 0.66-1) and 0.82 (95% CI, 0.59-1), respectively. The gastric intraluminal PCO2 was higher in patients who failed (p < .05). When gastric intraluminal PCO2 was . or =40 torr during the initial evaluation, weaning failure occurred with a sensitivity of 1 (95% CI, 0.31-1) and a specificity of 0.55 (95% CI, 0.26-0.84). CONCLUSIONS: Weaning failure was associated with gastric intramucosal acidosis. The intramucosal pH and gastric intraluminal PCO2 may be helpful to predict weaning outcome. Further controlled clinical trials in a larger group of patients are needed.     

动静脉血pH和二氧化碳分压差与胃粘膜pH监测组织氧合相关性的实验研究

目的：探讨反应组织氧合状况简便易行而有实用价值的指标。方法：用致病性大肠村菌活菌液制备兔感染性休克模型（实验组１０只,对照组６只注射等量生理盐水）,观察实验组与对照组在种菌前,种菌后０．５,１．０,１．５,２．０和２．５平均动脉压（ＭＡＰ）,胃粘膜ｐＨ值（ｐＨｉ）和动,静脉血ｐＨ（ａ－ｖｐＨ）及二氧化碳分压差（ｖ－ａＰＣＯ２）的变化及其相关性。     

Effects of fluid challenge on gastric mucosal PCO2 in septic patients

Objective To determine the effects of fluid challenge on systemic hemodynamic variables and gastric intramucosal partial pressure of carbon dioxide (PCO₂) in septic patients.Design Short-term interventional study.Setting Medical-surgical intensive care unit in a university hospital.Patients Twenty-four adult patients with severe sepsis or septic shock requiring volume replacement. All patients were studied within 24 h of onset of severe sepsis or septic shock.Interventions Five hundred milliliters of a 6% hydroxyethyl starch (HES) solution were administered in 30 min.Measurements and results Complete hemodynamic data, blood samples, and gastric mucosal PCO₂ (automatic gas capnometry) determinations were obtained at baseline and 15 min after the end of fluid infusion. After fluid challenge, cardiac index (CI) increased from 3.8 (range 2.9–4.2) to 4.2 (range 3.1–4.9) l/min m^–2 (p<0.05). The PCO₂ gap decreased from 9.8 (range 6.9–26.0) to 8.5 (range 6.6–17.4) mm Hg (p<0.05), but important individual variations were observed. We failed to observe significant relationships between changes in CI and in PCO₂ gap, or between indices of preload (pulmonary artery occluded pressure, right atrial pressure, and pulse pressure variations) and changes in PCO₂ gap. In addition, changes in PCO₂ gap and in (v-a) CO₂ were not related; however, changes in PCO₂ gap were related to baseline PCO₂ gap (p=0.003), PEEP (p=0.02), and cumulative doses of vasopressors (p=0.02).Conclusions The effects of fluid challenge on gastric mucosal PCO₂ are variable and related to baseline PCO₂ gap rather than to systemic variables. In general, rapid volume infusion decreases PCO₂ gap, but this effect is more pronounced in patients with presumably impaired mucosal perfusion.Electronic Supplementary Material Supplementary material is available in the online version of this article at