Use of autologous blood as part of the perfusate for cardiopulmonary bypass: a priming technique

In an attempt to replace the oncotic and protein coating capabilities of serum albumin in the perfusate, we established a priming protocol that used autologous blood as part of the perfusate solution. Prior to March 1, 1999, our standard priming protocol was 1650 ml of crystalloid with 250 ml of 5% serum albumin and 5,000 units of heparin. After removing albumin from our prime, our standard protocol was altered to include 40 ml of the patient's autologous blood in 1,800 ml of crystalloid and 10,000 units of heparin. To determine the intraoperative effects of using albumin/crystalloid primes (Group A), autologous blood/crystalloid primes (Group B) and crystalloid primes (Group C), a total of 178 patients were sequentially evaluated. Intraoperative parameters evaluated were total protein (TP), colloid osmotic pressure (COP), platelets (Plts) and fluid requirements during cardiopulmonary bypass (CPB). During an overlapping 12-month period of time, 1,092 consecutive cardiac surgical cases using CPB (584 albumin prime; 508 autologous blood prime) were evaluated for clinical outcomes in terms of mortality and length of hospitalization. In addition, over a period of 15 months, 1,458 patients in both the autologous blood/crystalloid group and the crystalloid only group were evaluated for the incidence of high-pressure excursions (HPE) after going on bypass. Comparative reviews of TP, COP and Plts demonstrated no significant difference 10 min after the start of bypass between Groups A and B. However, in Group C, there was a statistically significant increase in the intraoperative fluid requirements during CPB, compared to both of the other groups. There was no significant difference in the incidence of HPE, with an occurrence of 1.04% in the crystalloid only group and 1.11% in the autologous blood/crystalloid group. Autologous blood perfusates were identical to albumin perfusates in their platelet protection and reduction of fluid shifts during the intraoperative period.     

Impact of modifying priming components and fluid administration using miniaturized circuitry in neonatal cardiopulmonary bypass

Following a succession of changes in circuitry and priming additives between 1993 and 1998, a comprehensive re-evaluation of neonatal cardiopulmonary bypass (CPB) practice was undertaken. Samples from 10 infants (Group 1) undergoing CPB were evaluated for osmolality, oncotic pressure, total protein, hematocrit, glucose, and electrolytes (Na+, K+, iCa2+). These samples were tested at six measurement points: (1) after priming, (2) patient pre-CPB, (3) CPB-start, (4) CPB-mid, (5) CPB-end, and (6) post-modified ultrafiltration (MUF). Prime volumes were also carefully measured as well as the type and amount of volume given during CPB. After evaluating the initial data, changes in protocol regarding mannitol, calcium correction, and oncotic strength on CPB were made. Following implementation of these protocol changes, a second set (Group 2) of 10 infants was identically evaluated. Group 1 prime osmolality was 379 +/- 44 mOsm/kg, while Group 2 prime osmolality was 324 +/- 14 mOsm/kg (p = 0.003). There were no differences in osmolality between groups during bypass and osmolality was unaffected by modified ultrafiltration. Ionized calcium levels were significantly different at the end of bypass between Group 1, 0.6 +/- 0.1 mmol/l; and Group 2, 1.17 +/- 0.24 mmol/l (p < 0.001). In Group 1, there was a 40% drop (p = 0.001) in colloid osmotic pressure (COP) levels from pre-CPB (13.3 +/- 3.4 mmHg) to CPB-end (8.8 +/- 1.2 mmHg). In Group 2, there were no differences in COP during CPB. COP levels of Group 1 and Group 2 at CPB-end were 8.8 +/- 1.2 mmHg and 14 +/- 1.9, respectively (p < 0.0001). Total volume addition during bypass for Group 1 was 363.5 +/- 148.7 ml and for Group 2 was 245.1 +/- 92.2 ml (p < 0.05). In conclusion, progressive changes in neonatal circuits and techniques can have potentially wide-ranging effects on electrolyte and osmotic/oncotic homeostasis. An audit of perfusion management through expanded laboratory tests is recommended, especially in periods of change.     

小儿心内直视手术控制胶体渗透压的研究

目的：探讨小儿心脏直视手术围体外循环期胶体渗透压的变化规律。方法：将68例先心病患儿随机分成4组，分别以晶体液、血浆、人血白蛋白、血定安预充，观察胶体渗透压和临床一些指标的变化及比较组织的湿干重比。结果：以人血自蛋白、血定安预充与以晶体液、血浆预充相比，前两者能够在体外循环中维持较理想的胶体渗透压；组织的湿干重比升高幅度较小；术后辅助呼吸时间较短，出现眼球结膜、眼睑水肿的比率较低。结论：维持小儿体外循环过程中适当的胶体渗透压有助于患儿康复，减少并发症；以人血自蛋白和血定安预充能够较好维持所需水平的胶体渗透压，且安全、有效。     

A hyperosmolar-colloidal additive to the CPB-priming solution reduces fluid load and fluid extravasation during tepid CPB

Cardiopulmonary bypass(CPB) is associated with fluid overload. We hypothesized that fluid gain during CPB could be reduced by substituting parts of a crystalloid prime with 7.2% hypertonic saline and 6% poly (O-2-hydroxyethyl) starch solution (HyperHaes). 14 animals were randomized to a control group (Group C) or to Group H. CPB-prime in Group C was Ringer's solution. In group H, 4 ml/kg of Ringer's solution was replaced by the hypertonic saline/hydroxyethyl starch solution. After 60 min stabilization, CPB was initiated and continued for 120 min. All animals were allowed drifting of normal temperature (39.0 degrees C) to about 35.0 degrees C. Fluid was added to the CPB circuit as needed to maintain a 300-ml level in the venous reservoir. Blood chemistry, hemodynamic parameters, fluid balance, plasma volume, fluid extravasation rate (FER), tissue water content and acid-base parameters were measured/calculated. Total fluid need during 120 min CPB was reduced by 60% when hypertonic saline/hydroxyethyl starch solution was added to the CPB prime (p < 0.01). The reduction was related to a lowered FER. The effect was most pronounced during the first 30 min on CPB, with 0.6 (0.43) (Group H) compared with 1.5 (0.40) ml/kg/min (Group C) (p < 0.01). Hemodynamics and laboratory parameters were similar in both groups. Serum concentrations of sodium and chloride increased to maximum levels of 148 (1.5) and 112 (1.6) mmol/l in Group H. To conclude: addition of 7.2% hypertonic saline and 6% poly (O-2-hydroxyethyl) starch solution to crystalloid CPB prime reduces fluid needs and FER during tepid CPB.     

Colloid osmotic pressure and fluid resuscitation with hetastarch, albumin, and saline solutions

The effects of fluid resuscitation with 6% hetastarch, 5% albumin, or 0.9% saline solutions on plasma colloid osmotic pressure (COP) were examined in 26 patients with hypovolemic circulatory shock. One liter of hetastarch produced a 36% increase in COP compared to an 11% increase after 1 L of albumin (p less than 0.001). One liter of saline resulted in a 12% decrease in COP (p less than 0.05). The mean COP increased from 16.3 +/- 1.6 (SE) mm Hg to a maximum of 23.7 +/- 1.4 mm Hg during the first 24 h of hetastarch resuscitation (p less than 0.01), and from 17.0 +/- 1.1 to 22.3 +/- 1.5 mm Hg with albumin (p less than 0.001). Saline resuscitation decreased the COP from 17.1 +/- 1.1 mm Hg to a minimum of 12.7 +/- 1.1 mm Hg (p less than 0.02). These changes persisted from 2-5 days after resuscitation. Saline resuscitation required significantly larger amounts of fluid. The authors conclude that fluid resuscitation of circulatory shock with colloid solutions increases COP and requires less volume of resuscitative fluid.     

180 ml and less: cardiopulmonary bypass techniques to minimize hemodilution for neonates and small infants

OBJECTIVE: To determine the efficacy of decreasing cardiopulmonary bypass (CPB) prime volume for neonates and small infants by using low prime oxygenators, small diameter polyvinyl chloride (PVC) tubing and removing the arterial line filter (ALF) in an effort to reduce intraoperative exposure to multiple units of packed red blood cells (PRBC). METHODS: Two retrospective database studies comparing neonatal CPB prime volume were undertaken: Study 1--A CPB circuit consisting of a 1/8 inch arterial line, a 3/16 inch venous line and a low prime oxygenator with 172 ml total circuit prime (n=74) was compared to a circuit with a 3/16 inch arterial line, a 1/4 inch venous line and a higher prime oxygenator with a 350 ml total circuit prime (n=74). Study 2--The 172 ml circuit (n=389) was compared to a circuit that included an ALF and had a total circuit prime volume of 218 ml (n=389). RESULTS: Study 1--of the 74 neonates and small infants whose CPB prime volume was 350 ml, 19 were exposed to two or more intraoperative exogenous PRBC units while only 3 neonates and small infants in the 172 ml prime group (n=74) received two or more units (p = 0.0002). Study 2--of the 389 neonates and small infants where an ALF was used (prime volume 218 ml), 54 were exposed to two or more exogenous PRBC units while only 36 of the 389 patients where an ALF was not used (prime volume 172 ml) received two or more units of intraoperative PRBCs (p = 0.0436). CONCLUSION: Decreasing the neonatal and small infant extracorporeal circuit prime volume by as little as 46 ml resulted in significantly fewer multiple exposures to exogenous PRBC units.     

Plasma colloid osmotic pressure in healthy infants

Background  

The plasma colloid osmotic pressure (COP) plays a major role in transcapillary fluid balance. There is no information on plasma COP of healthy infants beyond the first post-natal week. The normal COP in healthy adult subjects (25 mmHg) is currently also applied as a reference value for healthy infants. This study was designed to test whether plasma COP values in healthy infants are the same as those in normal adults.     

Intraoperative fluid balance during cardiopulmonary bypass: effects of different mean arterial pressures

INTRODUCTION: This study investigated whether two levels of mean arterial pressure (MAP) during cardiopulmonary bypass did influence per-operative fluid shifts. METHODS: Sixteen pigs underwent 60 minutes of normothermic cardiopulmonary bypass (CPB) followed by 90 minutes of hypothermic CPB. Eight animals had a MAP of 60-80mmHg by norepinephrine (HP group). Another 8 animals had a MAP of 40-45 mmHg by phentolamine (LP group). Blood chemistry, plasma/interstitial colloid osmotic pressures, plasma volume, fluid balance, fluid extravasation rate and tissue water content were measured or calculated. RESULTS: The plasma volume was significantly lower in the HP group compared with the LP group after 60 minutes of CPB. Net fluid balance was 0.18 (0.05) ml x kg(-1) x min(-1) in the HP group and 0.21 ml x kg(-1) x min(-1) in the LP group (P > 0.05) while fluid extravasation rate was 1.18 (0.5) and 1.13 (0.4) ml x kg(-1) x min(-1) in the HP group and the LP group during CPB (P > 0.05). CONCLUSION: Net fluid balance and fluid extravasation rate were similar in the animals with elevated and with lowered MAP during CPB.     

Is compartment pressure related to plasma colloid osmotic pressure, in patients during and after cardiac surgery?

Haemodilution is always considerable during cardiopulmonary bypass (CPB). If this extra fluid sits in the muscle compartments then a corresponding rise in the compartment pressure (CP) is to be expected. The aim of this study was to measure pressure changes in a body compartment with new equipment, the MTC (Microtransducer). Changes in plasma colloid osmotic pressure (COP) were also measured during and after CPB to find a connection, if any, between CP and plasma COP. Ten elective consecutive CPB patients were studied. A 3-French (3-F) catheter-size electronic MTC was inserted in an anterior tibial compartment before CPB. The CP was monitored for 48 h. Plasma COP was also measured before, during and after CPB. CP increased significantly during and after CPB in all patients (p=0.01). COP decreased significantly in all patients (p=0.005), but no correlation was found between changes in COP and CP values in this study. Most of the patients reached their highest CP just after weaning off bypass. The CP remained elevated for 48 h, even though it then tended to decrease again. None of the patients reached the starting value within 48 h. COP decreased rapidly after going on bypass, but returned towards its starting value approximately 6 h after bypass. It is concluded that CP increases considerably during and after CPB and stays increased for at least 2 days after CPB. COP decreases during CPB, but reaches normal values 6 h after the CPB. No correlation was found between changes in CP and COP The MTC is a safe and easy way to measure intracompartment pressure.     

负平衡液体管理在瓣膜置换术体外循环中的应用效果

目的 探讨负平衡液体管理在瓣膜置换术体外循环(CPB)中的应用效果及对患者术后早期恢复的影响.方法 选取2019年1月至2020年1月我科收治的60例心脏瓣膜病患者作为研究对象,根据随机数字表法将其分为A组(30例,负平衡液体管理)与B组(30例,平衡或适当正平衡液体管理).比较两组患者的临床效果.结果 两组的升主动脉...     

A combined approach for improving cardiopulmonary bypass in coronary artery surgery: a pilot study

BACKGROUND: This is a pilot study carried out to assess the feasibility and the clinical impact of a combined approach of cardiopulmonary bypass (CPB) with reduced anti-coagulation. METHODS: We used a retrospective, non-randomized analysis of 45 consecutive patients undergoing coronary artery bypass using standard CPB with full anticoagulation (activated clotting time, ACT, > 450 s) (Group 1; n = 23) or closed, heparin-coated CPB with low anticoagulation (ACT>250 s), precise heparin and protamine titration, controlled suction, and retrograde autologous prime (Group 2; n = 22). RESULTS: Patients were similar except for a higher incidence of three-vessel disease in Group 2 (77.3% versus 47.8%; p < 0.03). Heparin was reduced by 41% in Group 2 and protamine by 56% (p < 0.0001). Total postoperative blood loss was similar between Groups 1 and 2 (429 +/- 149 versus 435+/-168 ml, respectively). However, the operative hematocrit decrease was lower in Group 2 (-1.6 +/- 7.5% versus -6.9 +/- 4.8%; p = 0.007), although hemodilution was similar, as reflected by the blood protein level. The need for postoperative inotropic support was less frequent in Group 2 (36.4% versus 65.2%; p = 0.05). Within the subgroup of patients weaned from CPB without requiring inotropic support (n = 35), the cardiac index dropped significantly in Group 1 (p = 0.003) 6 h after the start of CPB, whereas it remained stable in Group 2 (p = 0.92). Using multivariate analyses, Group 2 was found to be more protected than Group 1 against myocardial cellular injury (p = 0.046) and need for postoperative inotropic support (p = 0.014). CONCLUSION: The pejorative postoperative outcome in coronary artery surgery was attenuated through a combined approach aimed at improving CPB.     

Low molecular starch versus gelatin plasma expander during CPB: does it make a difference?

BACKGROUND: Non-protein plasma expanders carry a risk of potentially severe allergic reactions. As prime for cardiopulmonary bypass, we routinely use a gelatin plasma expander. Plasma expanding during anesthesia is achieved with high molecular starch (200/0.5 kDalton) in combination with Ringer Lactate solution (RL) and in the Intensive Care Unit (ICU) with a low molecular starch (130/0.4 kDalton). We evaluated the feasibility of low molecular starch in combination with RL (group LMSRL) versus gelatin plasma expanding (group GPE) for priming CPB circuits in patients undergoing cardiac surgery in a randomized prospective trial. METHODS: One hundred and eighty adults who underwent primary valve or coronary artery bypass graft (CABG) surgery were equally stratified into 3 series of 60 patients with the routinely used oxygenators; Capiox RX-25, CML Duo and Quadrox-D. Then they were randomised by drawing lots and allocated into the LMSRL or GPE groups. We compared hematocrit, hemoglobin, platelet count, activated clotting time (ACT), lactate and colloid osmotic pressure (COP), blood loss, transfusion need, urine production and ICU stay. In addition, we monitored the average trans-oxygenator fluid resistance (AFR) for each type of oxygenator. RESULTS: The COP is significantly lower in the LMSRL group (20mmHg +/- 0.2 versus 18 mmHg +/- 0.2, p < 0.0001); as was the total use of plasma expanders (3846 ml +/- 98 versus 3059 ml +/- 77, p < 0.001). All other parameters were not significantly different. When comparing the observed AFR for the three types of oxygenators, a lower AFR in the LMSRL group (p < 0.02) was noted for the Capiox RX-25. CONCLUSIONS: This study shows a lower need for plasma expanders in patients who receive only starch plasma expanders. Further, we noted a lower COP in the LMSRL group, but since the mean COP was >17 +/- 0.2 mmHg, this cannot be considered of clinical importance. In conclusion, our study result supports the use of low molecular starch as a good alternative choice for priming CPB.     

Does β2-adrenergic stimulation attenuate fluid extravasation during hypothermic cardiopulmonary bypass? An experimental study in pigs

Objectives: Hypothermic cardiopulmonary bypass (CPB) is associated with increased fluid filtration, edema formation and, occasionally, organ dysfunction. Cold-induced reduction in endothelial barrier function may play a role. β(2)-adrenergic activation elevates cellular cyclic adenosine monophosphate (cAMP) which maintains endothelial barrier properties. In this study, we tested whether β-adrenergic stimulation could influence the increase in fluid extravasation observed during hypothermic CPB. Materials and methods: Fourteen pigs randomly received terbutaline infusion (T-group) (n=7) or a control infusion (C-group) (n=7). All animals were given 60 min of normothermic CPB, followed by 90 min of hypothermic CPB. Fluid input and losses, plasma volume, colloid osmotic pressures (plasma, interstitial fluid), hematocrit, serum proteins and total tissue water content were measured and the fluid extravasation rates (FER) calculated. Statistics: by SPSS. Values presented as mean ± SD. Repeated measure analysis of variance was performed and a t-test used when appropriate. RESULTS: The commencement of normothermic CPB resulted in a 20% hemodilution, with an abrupt increase in fluid requirements during the first 10 min. FER increased from 0.18 (0.06) pre-bypass to 0.78 (0.27) ml/kg/min (T-group) (p=0.002) and from 0.16 (0.05) to 0.93 (0.26) ml/kg/min (C-group) (p<0.001) with no between-group differences. Thereafter, FER stabilized at a level of 0.32 (0.13) and 0.27 (0.14) ml/kg/min in the T-group and C-group, respectively. After the start of cooling, FER increased in the T-group to 0.55 (0.12) ml/kg/min (P=0.046) and in the C-group to 0.54 (0.13) ml/kg/min (P=0.006), with no between-group differences (P=0.738). CONCLUSION: In the present experimental study, we were unable to demonstrate any clinically relevant modulating effect of terbutaline on fluid extravasation during hypothermic cardiopulmonary bypass.     

MAST system: a new condensed cardiopulmonary bypass circuit for adult cardiac surgery.

There have been many refinements in cardiopulmonary bypass (CPB) techniques over the past few decades specific to design, materials and function. Despite these improvements, use of the standard length circuit tubing and pump oxygenator alter cellular, biochemical and rheological properties by inducing a systemic inflammatory response, persisting well into the early postoperative phase. We have designed a new condensed CPB circuit, the MAST system, where the oxygenator and the pumps are brought closer to the operating table (within 30 inches) with the help of a series of telescopic swivel steel poles to which they are attached. The control console is retained at the usual remote location of 2ft behind the MAST system. This configuration accomplishes a decrease in tubing length, priming volume and blood circulatory time within the extracorporeal circuit. Early experience of a hundred consecutive cases utilizing the MAST CPB system is presented along with a comparative analysis of prime volume, hemodilution and transfusion parameters of MAST system vs the low prime system, which is another newly developed CPB circuit utilizing a pediatric oxygenator to reduce prime volume and hemodilution.     

Plasma osmotic changes during major abdominal surgery

Fluid balance across the capillary membrane is maintained normally by a balance of hydrostatic and colloid osmotic pressures (COP). In 12 patients having major intra-abdominal procedures, the COP was followed during the operative and immediate postoperative periods. The patients' intraoperative fluid management consisted of replacing shed blood with blood and following Shires' concept of crystalloid replacement. Significant decreases in COP to approximately two thirds of the initial value occurred in patients having intra-abdominal procedures versus only a 10 percent decrease in those having peripheral procedures (greater than .001). As a result of this decrease in COP, the balance between hydrostatic and colloid osmotic pressures is lost and risk of pulmonary intersitial edema is increased.     

Changes in colloid osmotic pressure in patients undergoing cardiothoracic surgery

Measurements of plasma colloid osmotic pressure (COP) were made during and for 24 h after normothermic continuous flow cardiopulmonary bypass (CPB) in 20 adults exposed to sudden haemodilution by a crystalloid pump prime solution. Haematocrit, albumin and total protein were also measured. Within 5 min of starting bypass the mean COP fell to 45% pre-bypass value and remained at this level until bypass was discontinued. Following bypass, the oncotic pressure rose rapidly during the first hour to 84% of the pre-bypass value, and then more slowly until it reached the pre-bypass value 24 h later.The trend seen for plasma proteins and haematocrit was similar but the fall was smaller, 65–70% of the pre-bypass values. This significant difference in fall between plasma protein concentration and directly measured COP is explained by their non-linear relationship.Three patients died soon after bypass. They all showed significantly lower values of COP than the mean for the group as a whole at some stage (P < 0.05).     

Colloid oncotic pressure as a guide for the anesthesiologist in directing fluid therapy

One useful but underused parameter of fluid replacement is colloid oncotic pressure. Colloid oncotic pressure (COP) is one of the Starling forces that maintain a balance between intravascular and extravascular fluid. Systemic and pulmonary circulations exhibit differences that limit the usefulness of COP manipulation in the treatment of pulmonary edema, especially that associated with hypoxic damage or pulmonary contusion. Systemic transcapillary fluid transport, however, is governed significantly by COP, and serial measurements of COP can serve as useful guides for colloid replacement. In this paper we present instances in which COP determinations were found to be clinically helpful, and discuss colloid replacement during surgery.     

Effect of hemodilution on capillary and arteriolovenous shunt flow in organs after cardiac arrest in dogs

The purpose of this study was to observe the changes in capillary and arteriolovenous shunting blood flow after cardiac arrest and subsequent resuscitation by venous return occlusion produced by inflation of an intra-atrial balloon and cross-clamping of the ascending aorta, and to determine how hemodilution might modify such changes. Organ capillary blood flow and the fractional distribution of cardiac output were measured by the microsphere (9-microns diameter) trapping method in dogs. Simultaneously, the arteriolovenous shunt rate was measured by continuous collection of venous blood drained at 4.8 ml.min-1 for 2 min from the brain, kidney, liver, splanchnic organs, skeletal muscle of the pelvic limb, and all of the systemic circulatory organs. The capillary blood flow of the brain, thyroid gland, pancreas, and stomach decreased after circulatory arrest in five nonhemodiluted dogs (group C); arteriolovenous shunt rate was unchanged after circulatory arrest in this group. However, with hemodilution, which was induced either before (pre group, n = 5) or after (post group, n = 5) circulatory arrest, no change occurred in the shunt rate in any of the organs, with the exception of an increase in the systemic arteriolovenous shunt rate in the pre group. Capillary blood flow was maintained at almost the same level as before circulatory arrest in the pre group, but increased significantly in several organs of the post group. The data indicated that hemodilution might be effective for prevention of organ ischemia after cardiac arrest.     

术前应用6%羟乙基淀粉行急性高容量血液稀释对老年患者动脉压及氧代谢的影响

目的：探讨应用6％羟乙基淀粉行急性高容量血液稀释（AHH）对老年患者动脉压和氧代谢的影响。方法：随机选择腹部择期手术的老年患者40例,随机分为两组,A组为高容量血液稀释组,B组为非血液稀释组。B组入室后补充基础生理需要量及禁食丧失需要量。A组患者以25ml／min的速率输入6％羟乙基淀粉7ml／kg后诱导,同时继续输入达15ml／kg行高容量血液稀释,分别监测记录基础值（T0）、诱导后插管前（T1）、插管后即刻（T2）、插管后5min（T3）、10min（T4）、20min（T5）、切皮前（L6）的平均动脉压（MAP）、心率（HR）、中心静脉压（CVP）。经桡动脉取血测血气、Lac。结果：A组患者诱导前后MAP无显著性差异（P〉0．05）,B组诱导后MAP显著降低（P〈0．05）。与同时相A组比较有显著性差异（P〈0．05）。A组CVP插管后5min（T3）与基础值（T0）比较有显著性差异（P〈0．05）。与同时相B组比较有显著性差异（P〈0．05）,两组患者HR诱导后减慢（P〈0．05）。A组血红蛋白（Hb）、细胞压积（Hct）在血液稀释后显著降低（P〈0．05）。两组血气、Lac在血液稀释前后无显著性变化（P〉0．05）。结论：适度AHH有利于维持老年患者血液动力学的稳定,而氧代谢改变不明显,值得临床推广。     

早产儿两种喂养方法的比较研究

目的比较两种喂养方法用于早产儿的效果.方法早产儿共58例,出生体重在1 500～2 000 g范围内,随机分为甲、乙两组,甲组30例,乙组28例,甲组以微量泵通过鼻饲管持续均匀泵奶每小时2～3 ml,乙组则采用常规间歇鼻饲法,以注射器通过鼻饲管每2小时注奶4～6 ml,两组均观察3～5 d,比较观察期间两组患儿平均每天进奶量,吐奶例数、残奶例数等指标.结果甲组患儿平均每日喂奶量明显高于乙组（P＜0.05）,且吐奶例数,残奶出现例数明显少于乙组（P＜0.05）.结论早产儿采用微量泵鼻饲持续均匀泵奶效果明显优于常规间歇鼻饲喂奶法.