Effect of low volume ventilation during cardiopulmonary bypass on oxygenation and postoperative pulmonary outcome

Objective

This study was carried out to evaluate effect of low volume normal frequency ventilation during Cardiopulmonary Bypass (CPB) on immediate postoperative respiratory outcome in patients undergoing elective open heart surgeries.

Background

Lung deflation during CPB is considered as major cause of postoperative pulmonary dysfunction. Various methods of ventilation had been tried during CPB to prevent postoperative lung dysfunction. As yet, little information is available comparing low volume normal frequency ventilation with no ventilation during CPB.

Patients and Methods

Thirty six patients aged 18 years to 65 years were included and randomized into two groups; Group V (n?=?18) or Group NV (n?=?18). Group V patients were ventilated with a tidal volume of 2 mL?kg^?1with 100 % oxygen during CPB after aortic clamp placement, and respiratory rate was continued as per pre CPB period. Ventilation was discontinued in NV group after aorta was cross clamped. Normal ventilation was restored in both groups after release of aortic clamp.

Results

Intraoperative PaO₂ and PaCO₂ were similar in both groups. The group V patients had improved inspiratory capacity (p?=?0.0) in both day 1 (after extubation) and day 2 (24 h after extubation). Extubation was significantly earlier in group V patients (p?<?0.05).

Conclusion

Low volume normal frequency ventilation during cardiopulmonary bypass improves lung mechanics during early postoperative period in patients undergoing open heart surgery.     

脉搏灌注变异指数在不同容量状态下预测容量反应的效果

目的探讨急性等容血液稀释(ANH)和急性高容血液稀释(AHH)期间脉搏灌注变异指数(PVI)预测患者容量变化的有效性。方法选取择期手术患者30例,男22例,女8例,年龄18～65岁,BMI30 kg/m~2,ASAⅠ或Ⅱ级。按照血液稀释的方法不同分成两组:等容血液稀释组(ANH组,n=15)和高容血液稀释组(AHH组,n=15)。ANH组从5个时点采集数据:基础值(全麻诱导插管后)、第1次抽出5%预估血容量(EBV)、第2次抽出5%EBV、第1次输注同等容量的6%羟乙基淀粉溶液(HES)、第2次输注5%EBV的HES;AHH组从3个时点采集数据:基础值、第1次输注5%EBV的HES、第2次输注5%EBV的HES。记录以上时点的PVI,对PVI和不同容量状态的反应进行相关性分析。结果 ANH组的基础血容量与PVI相关性较低(r=0.259,P=0.352);在ANH放血时,放血5%EBV与PVI(r=0.530,P0.05)及放血10%EBV与PVI(r=0.547,P0.05)相关性中等;在ANH回输时,回输5%EBV与PVI(r=-0.164,P=0.560)及回输10%EBV与PVI(r=-0.160,P=0.569)相关性较低。AHH组的基础血容量与PVI相关性较低(r=0.146,P=0.603);在AHH扩张容量时,扩容5%EBV与PVI(r=-0.538,P0.05)及扩容10%EBV与PVI(r=-0.577,P0.05)相关性中等。结论不论是低容量还是高容量状态,PVI均能够预测容量反应,但敏感性一般。     

Effect of restrictive fluid management and acute normovolemic intraoperative hemodilution on transfusion requirements during living donor hepatectomy

The aim of this study was to evaluate the safety and effectiveness of a restrictive fluid management strategy and acute normovolemic intraoperative hemodilution (ANIH) to decrease transfusion requirements among living-donors for liver transplantation (LDLT). We retrospectively reviewed the data of 114 consecutive LDLT donors. The patients were divided into 2 groups based on whether (Group I; n = 73) or not (Group II; n = 41) a restrictive fluid management strategy with ANIH was used during the procedure. For each group we recorded demographic features, intraoperative and postoperative transfusions, amount of administered intraoperative crystalloid and colloids, intraoperative hemodynamics, preoperative and postoperative laboratory values (renal and liver functions), intraoperative and postoperative urine output, and length of hospital stay. Demographic features and preoperative laboratory values were similar for the 2 groups, except for age (Group I, 36 +/- 9 vs Group II, 33 +/- 8; P = .04). Intraoperatively, 7 patients (10%) in Group 1 and 9 (22%) in Group II required blood transfusions (P = .06). The respective amount of heterologous blood transfusion for Groups I and II was 96 +/- 321 mL vs 295 +/- 678 mL (P = .06). Postoperative renal and liver functions were not different between the 2 groups (P > .05). Patients in Group I had a shorter hospital stay than those in Group II (8.2 +/- 4.6 days vs 10.1 +/- 4.9 days; P = .03). In conclusion, a restrictive fluid management strategy with ANIH was a safe blood-salvage technique for LDLT. This approach was also associated with decreased length of hospital stay and a trend toward decreased transfusion requirements.     

Effect of inhalation injury on fluid resuscitation requirements after thermal injury

The presence of inhalation injury has been reported to increase fluid requirements for resuscitation from burn shock after thermal injury. To evaluate the effect of inhalation injury on the magnitude of burn-induced shock, the characteristics of resuscitation of 171 patients with burns covering at least 25 percent of the total body surface area were reviewed. When inhalation injury was suspected, confirmation by xenon-133 scanning, bronchoscopy, or both was obtained. Initial fluid resuscitation was calculated according to the Parkland formula, and titration was initiated to maintain a urine output of 30 to 50 ml/hour. Fifty-one patients had inhalation injuries. Patients with inhalation injuries had a mean fluid requirement of 5.76 ml/kg per percentage of total body surface area burned and a mean sodium requirement of 0.94 mEq/kg per percentage of total body surface area burned to achieve successful resuscitation, compared with a fluid requirement of 3.98 ml/kg per percentage of total body surface area burned and a sodium requirement of 0.68 mEq/kg per percentage of total body surface area burned for the group without inhalation injury (p less than 0.05). These data confirm and quantitate that inhalation injury accompanying thermal trauma increases the magnitude of total body injury and requires increased volumes of fluid and sodium to achieve resuscitation from early burn shock.     

Intraoperative autotransfusion in cardiac operations. Effect on intraoperative and postoperative transfusion requirements

The Southern Arizona Regional Red Cross Blood Program, in cooperation with two cardiac surgery groups, examined the effect of intraoperative autotransfusion on red cell, plasma, and platelet usage during and after cardiac operations. The study evaluated whether intraoperative autotransfusion influenced intraoperative or postoperative blood usage and whether regular use was more effective than selective use. The study demonstrated that intraoperative autotransfusion reduces intraoperative and postoperative blood use and that regular use of intraoperative autotransfusion is more effective than selective use.     

Effect of supplemental pre-operative fluid on postoperative nausea and vomiting

In a prospective, double-blind, randomised controlled trial, we studied the effects of pre-operative fluid load on post-operative nausea and vomiting. Eighty patients attending for laparoscopic cholecystectomy or gynaecological surgery were randomly allocated to receive 2 ml.kg-1 (conservative) or 15 ml.kg-1 (supplemental) Hartmann's solution intravenously, shortly before induction of anaesthesia. During the operation, fluid management was identical in both groups. During the first post-operative 24 h, post-operative nausea and vomiting occurred in 29 patients (73%) in the conservative fluid group and nine patients (23%) in the supplemental fluid group (p = 0.01). Supplemental pre-operative fluid is an inexpensive and safe therapy for reducing post-operative nausea and vomiting.     

Assessing fluid responsiveness by stroke volume variation in mechanically ventilated patients with severe sepsis

BACKGROUND AND OBJECTIVE: Our hypothesis was that stroke volume variation during mechanical ventilation of the lungs would allow accurate prediction and monitoring of changes in cardiac index in response to fluid loading in patients with severe sepsis. METHODS: This was a prospective clinical study in a university hospital. Ten mechanically ventilated patients with severe sepsis or septic shock were given fluid loading with 500 mL 10% hydroxyethylstarch 200/0.5 over 30 min. Before and after fluid loading pulmonary arterial occlusion pressure and central venous pressure were measured. Intrathoracic blood volume index, stroke volume variation and cardiac index were measured by the transpulmonary thermodilution technique. After verifying normal distribution of the data (skewness < 1.0) the paired t-test was used for statistical analysis. RESULTS: After fluid loading stroke volume variation decreased significantly, whereas central venous pressure, pulmonary arterial occlusion pressure, intrathoracic blood volume index and cardiac index increased significantly. Changes of cardiac index in response to fluid loading were correlated to baseline values of stroke volume variation (r = 0.64, P = 0.02) and intrathoracic blood volume index (r = -0.73, P = 0.009). Changes in cardiac index were significantly correlated to percentage changes in stroke volume variation (r = -0.65, P < 0.001) and changes in intrathoracic blood volume index (r = 0.52, P = 0.002), whereas changes in cardiac index revealed no significant correlation to changes in central venous pressure (r = 0.28, P = 0.07) and changes in pulmonary arterial occlusion pressure (r = 0.29, P = 0.06). CONCLUSIONS: Measuring stroke volume variation may be a useful way of guiding fluid therapy in ventilated patients with severe sepsis because it allows estimation of preload and prediction of cardiac index changes in response to fluid loading.     

Influence of surgeons' experience on postoperative sepsis

A prospective study was performed on 635 patients with appendicitis operated on by 7 trainees and 119 patients operated on by 6 senior surgeons with more than 8 years of surgical experience. In patients with normal appendices, postoperative sepsis was extremely low. For early and late appendicitis, the infection rates of the trainees decreased as experiences accumulated, but they were still higher than that of the senior surgeons. The difference in infection rates in acute appendicitis did not reach statistical significance between any of the training stages and between the various stages and the rate of the senior surgeons. The differences in infection rates in late appendicitis between stage 1 and stage 3 was significant, as was the difference in infection rates between stage 1 and the infection rate of the senior surgeons. Therefore, we have concluded that overall, the limited experience of trainees is related to the rate of postoperative sepsis in late appendicitis, although the infection rates of individual trainees vary a lot.     

目标导向液体治疗对肥胖患者术后康复的影响

目的探讨目标导向液体治疗对肥胖患者术后康复的影响。方法选择择期行腹腔镜袖状胃切除术的重度肥胖患者60例,男28例,女32例,年龄30~55岁,BMI 40~45 kg/m^2,ASAⅡ或Ⅲ级,采用随机数字表法分为两组,每组30例:目标导向液体治疗组(G组)和常规液体治疗组(C组)。G组采用FloTrac/Vigileo监测系统监测每搏量(SV)、每搏量变异度(SVV),维持每搏变异度(SVV)≤13%。C组维持HR及MAP波动幅度不超过术前20%,尿量>0.5 ml·kg^-1·h^-1。记录术中出血量、输注晶体液量、胶体液量及总输液量、尿量以及血管活性药物的使用情况。记录术后拔管时间、术后首次排气时间、术后住院时间。记录术后心血管并发症、肺部并发症和肾功能损害的发生情况。采用GIQLI量表评定术前及术后2、5、10、16周的生存质量。结果与C组比较,G组术中输注晶体液量、总输液量和尿量明显减少(P<0.05),术后首次排气时间、术后住院时间明显缩短(P<0.05),术后心血管并发症、肺部并发症发生率明显降低(P<0.05)。术后2、5、10周G组GIQLI评分明显高于C组(P<0.05)。两组术中出血量、输注胶体液量、血管活性药物使用率、术后拔管时间、肾功能损害发生率差异无统计学意义。结论基于FloTrac/Vigileo监测系统的目标导向液体治疗可促进肥胖患者术后康复,具有一定的临床价值。     

Comparison of preoperative with postoperative lignocaine infiltration on postoperative analgesic requirements

Ninety patients undergoing appendicectomy were allocated randomlyto receive 1.5% lignocaine 15 ml with adrenaline infiltratedinto the proposed wound line 3 min before incision, lignocaine15 ml with adrenaline infiltrated into the wound on closureor no wound infiltration. After operation, all patients receivedpethidine by patient-controlled analgesia. Pain scores wereassessed while supine and sitting on day 1 and 2 and the cumulativepethidine dose administered was recorded at 12, 24, 36 and 48h after operation. There were no significant differences inthe cumulative dose of pethidine required or pain scores betweenthe three groups at any time point after operation. We concludethat pre-incisional infiltration with 1.5% lignocaine had noadvantage compared with infiltration at wound closure or nowound infiltration in reducing postoperative analgesic requirementsor pain scores after appendicectomy. (Br. J. Anaesth. 1994;72: 541–543)     

Detection of sepsis in the postoperative patient

It becomes evident, therefore, that there is no one indicator, either clinical or laboratory, sufficient to diagnose infection in the postoperative patient. Only a skillful clinician using the multiple modalities available and combining them with a careful history and physical examination and a high index of suspicion will be able to diagnose and treat infection in a timely manner and so avoid the physical, emotional, and fiscal costs of a late or missed diagnosis.     

以每搏量变异为指导的液体治疗对精准肝切除术患者乳酸和术后肝肾功能的影响

目的探讨以每搏量变异(SVV)为指导的液体治疗策略对精准肝切除术患者乳酸和术后肝肾功能的影响。方法择期行精准肝切除术患者50例,ASAⅠ～Ⅲ级,随机分为低中心静脉压组(LCVP组)和目标导向组(SVV组)。LCVP组:通过限制输液、调整体位、利尿等措施维持CVP低于5cm H2O。SVV组:患者桡动脉穿刺成功后连接FloTrac/Vigileo换能器,监测患者心指数和SVV。在控制CVP低于5cm H2O的前提下,输注6%羟乙基淀粉溶液(130/0.4)使得SVV低于12%。记录手术期间低血压的发生情况、去氧肾上腺素使用量、术中出血量、术中输液、输血量,测定手术前、切皮后2、4h和手术结束时的乳酸浓度以及术前、术后1、2、5d的总胆红素、直接胆红素、白蛋白和尿素氮的变化,并记录患者的住院天数和术后30d死亡率。结果 SVV组患者术中发生低血压的次数、去氧肾上腺素用量明显少于LCVP组(P0.05或P0.01);6%羟乙基淀粉溶液(130/0.4)的术中用量明显多于LCVP组(P0.05)。两组患者在切皮后4h、手术结束时乳酸浓度均明显高于术前(P0.01),且SVV组明显低于LCVP组(P0.01)。术后1、2、5dLCVP组和术后1,2dSVV组患者白蛋白浓度明显低于术前(P0.05),术后5dSVV组患者白蛋白浓度明显高于LCVP组(P0.05)。结论采用SVV为指导的目标导向液体治疗,能明显减少术中的低血压发生,降低血管活性药物的用量和乳酸浓度,改善术后低蛋白血症。     

Predicting increased fluid requirements during the resuscitation of thermally injured patients

BACKGROUND: We determined whether factors present soon after burn predict which patients will receive more than 4 mL/kg/% burn during the first 24 hours, and whether total fluid intake during the first 24 hours (VOL) contributes to in-hospital mortality (MORT). METHODS: We reviewed the records of patients admitted during 1987-97. The modified Brooke resuscitation formula was used. One hundred four patients met inclusion criteria: total body surface area burned (TBSA) > or = 20%; admission directly from the field; weight > 30 kg; no electric injury, mechanical trauma, or blood transfusions; and survival > or = 24 hours postburn. Eighty-nine records were complete. RESULTS: Mean TBSA was 43%, mean full-thickness burn size was 21%, mean age was 41 years, mean VOL was 4.9 mL/kg/% burn, and mean lactated Ringer's volume was 4.4 mL/kg/% burn; 53% had inhalation injury. MORT was 25.8%. Mean urine output was 0.77 mL/kg/h. By linear regression, VOL was associated with weight (negatively) and full-thickness burn size (r2 = 0.151). By logistic regression, receipt of over 4 mL/kg/% burn was predicted at admission by weight (negatively) and TBSA; by 24 hours postburn, mechanical ventilation replaced TBSA. With respect to MORT, logistic regression of admission factors yielded a model incorporating TBSA and an age function; by 24 hours postburn, the worst base deficit was added. CONCLUSION: Burn size and weight (negatively) were associated with greater VOL. However, a close linear relationship between burn size and VOL was not observed. Mechanical ventilation supplanted TBSA by 24 hours as a predictor of high VOL. Worst base deficit, TBSA, and an age function, but not VOL, were predictors of MORT.     

Antioxidant therapy using high dose vitamin C: Reduction of postburn resuscitation fluid volume requirements

Twenty-four guinea pigs with third degree burns over 70% of the body surface area were divided equally into four groups. At 0.5 hours postburn, all groups received Ringer's lactate solution (R/L) according to the Parkland formula. The infusion rate was then reduced to 25% of the Parkland formula at 1.5 hours postburn. Group 1 received only R/L, and groups 2, 3 and 4 received adjuvant vitamin C (14.2 mg/kg/hr) until 4, 8, and 24 hours postburn, respectively. The volume of R/L was reduced by that of vitamin C solution so that the hourly sodium and fluid intake in each group was the same. Groups 1 and 2 demonstrated higher hematocrit and lower cardiac output values than did group 3, suggesting hypovolemia and hemoconcentration in these groups. Group 3 showed hematocrit and cardiac output values equivalent to those in group 4. We conclude that high dose vitamin C infusion maintains hemodynamic stability in the presence of a reduced resuscitation fluid volume provided vitamin C is administered for a minimum of 8 hours postburn.

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Resumen Un grupo de 24 curies con quemaduras de tercer grado sobre el 70% de la superficie corporal fueron divididos en 4 grupos. A las 0.5 horas postquemadura, todos los grupos recibieron lactato de Ringer (R/L) de acuerdo con la fórmula de Parkland. La tasa de infusión fue reducida luego a 25% de la fórmula de Parkland a las 1.5 horas postquemadura. El grupo 1 recibió R/L solamente y los grupos 2, 3 y 4 recibieron vitamina C coadyuvante (14.2 mg/kg/hr) hasta las 4, 8, y 24 horas postquemadura, respectivamente. El volumen de R/L fue reducido por el de la solución de vitamina C en tal forma que la ingesta horaria de sólido y de liquido fuera la misma en cada grupo. Los grupos 1 y 2 demostraron mayores valores de hematocrito y menores de gasto cardíaco en comparación con los animales en el grupo 3, lo cual sugiere hipovolemia y hemoconcentración en tales grupos. El grupo 3 demostró valores de hematocrito y de gasto cardiaco equivalentes a los del grupo 4. Nuestra conclusión es que la infusión de altas dosis de vitamina C mantiene la estabilidad hemodinámica en presencia de volúmenes reducidos de liquidos de reanimación, siempre y cuando se administre vitamina C por un mínimo de 8 horas postquemadura.

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Résumé Vingt-quatre cochons d'Inde brûlés au troisième degré à plus de 70% de leur surface corporelle ont été ensuite divisés en quatre groupes. Trente minutes après la brûlure, tous les animaux ont reçu une perfusion de Ringer lactate (R/L) selon la formule de Parkland. A 90 minutes, le débit de la perfusion a été réduite à 25% de la formule de Parkland. Les animaux dans le groupe I n'ont reçu que du R/L alors que les animaux des groupes 2, 3, et 4 ont reçu en plus de la vitamine C (14.2 mg/kg/hr), respectivement 4, 8, et 24 heures après leur brûlure. Le volume de R/L a été réduit proportionnellement de façon à ce que le volume total instillé chez chaque animal soit strictement le même. L'hématocrite et le débit cardiaque étaient plus élevés dans le groupe 1 et plus bas dans le groupe 2 par rapport au groupe 3 suggérant respectivement une hypovolémie et une hémoconcentration dans ces groupes. L'hématocrite et le débit cardiaque étaient similaires dans les groupes 3 et 4. Nous concluons que lorsque le volume de réanimation des brûlés est limité, l'infusion de vitamine C à haut dose est responsable de stabilité hémodynamique à condition qu'elle soit administrée au plus tard 8 heures après la brûlure.