Colloid Osmotic Pressure Values Research Articles

Effect of two different colloid priming strategies in infants weighing less than 5 kg undergoing on-pump cardiac surgeries.

Our aim was toexplore the effect of two different priming strategies (artificial colloid only vs. artificial colloid combined with human serum albumin) on the prognosis of children weighing less than 5 kg undergoing on-pump congenital heart disease (CHD) surgery. A total of 65 children weighing less than 5 kg who underwent on-pump CHD surgery in our hospital from September 2016 to December 2017 were enrolled in this study. The children were randomly divided into two groups: artificial colloid priming group (AC group, n=33) and artificial colloid combined albumin priming group (ACA group, n=32). The primary clinical endpoint was the peri-CPB colloid osmotic pressure (COP). Secondary clinical endpoints included perioperative blood product and hemostatic drug consumption, postoperative renal function, coagulation function, postoperative renal function, and postoperative recovery parameters. COP values were not significant in the priming system as well as peri-CPB time points between the two groups (P>.05). Platelet consumption in the AC group was significantly lower than that in the ACA group (P<.05). There were no significant differences in the use of other blood products and hemostatic drugs as well as perioperative coagulation parameters between the two groups (P>.05). Postoperative length of stay in the AC group was significantly lower than that in the ACA group (P<.05). There were no significant differences in mortality, postoperative mechanical ventilation time, ICU time, and perioperative adverse events (including postoperative AKI) occurrences between the two groups (P>.05). In the on-pump cardiac surgeries of patients weighing less than 5 kg, total colloidal priming would not affect peri-CPB COP values, postoperative coagulation function, and blood products consumption. Total artificial colloidal priming strategy is feasible in low-weight patients.

Fluid accumulation in the staged Fontan procedure: the impact of colloid osmotic pressures.

Despite Fontan surgery showing improved results, fluid accumulation and oedema formation with pleural effusion are major challenges. Transcapillary fluid balance is dependent on hydrostatic and colloid osmotic pressure (COP) gradients; however, the COP values are not known for Fontan patients. The aim of this study was to evaluate the COP of plasma (COPp) and interstitial fluid (COPi) in children undergoing bidirectional cavopulmonary connection and total cavopulmonary connection. This study was designed as a prospective, observational study. Thirty-nine children (age 3 months-4.9 years) undergoing either bidirectional cavopulmonary connection or total cavopulmonary connection procedures were included. Blood samples and interstitial fluid were obtained prior to, during and after the preoperative cardiac catheterization and surgery with the use of cardiopulmonary bypass (CPB). Interstitial fluid was harvested using the wick method when the patient was under general anaesthesia. Plasma and interstitial fluid were measured by a colloid osmometer. Baseline values were compared with data from healthy controls. Baseline COPp was 20.6 ± 2.8 and 22.0 ± 3.2 mmHg and COPi was 11.3 ± 2.6 and 12.5 ± 3.5 mmHg in the bidirectional cavopulmonary connection group and the total cavopulmonary connection group, respectively. These values were significantly lower than in healthy controls. The COPp was slightly reduced throughout both procedures and normalized after surgery. The COPi increased slightly during the use of CPB and significantly decreased after surgery, resulting in an increased COP gradient and was correlated to pleural effusion. Fluid accumulation seen after Fontan surgery is associated with changes in COPs, determinants for fluid filtration and lymphatic flow. NCT 02306057: https://clinicaltrials.gov/ct2/results?cond=&term=NCT+02306057.

Colloid osmotic pressure during and after surgical interventions in adult and geriatric dogs

ABSTRACT: The objective this study is to evaluate colloid osmotic pressure (COP) fluctuations in adult and senile dogs during surgical interventions. Thirty-six healthy dogs to surgical interventions, distributed in two groups, A and B, according to their age, and were all subjected to the same anesthetic protocol. Values of albumin, total plasmatic protein and COP were evaluated from samples collected before pre-anesthetic medication, fifteen minutes after pre-anesthetic medication, and shortly after the end of the intervention. Results were tested using t-test to compare among groups and ANOVA for repeated measures followed by Tukey’s test to compare different moments within the same group. Statistical significance was set at p&lt;0.05. In both groups, significant decreases were observed in colloid osmotic pressure, as well as albumin and total proteins (p&lt;0.001). Despite slightly lower COP values for the group of adult animals, this difference was not significant as there was a high individual variation within groups. The results therefore indicate no difference in colloid osmotic pressure values or fluctuation patterns among adult and senile dogs (p=0.124). The observed results indicate that colloid osmotic pressure decreases significantly during surgical procedures, due to hypotension caused by the anesthetic drugs and to hemodilution caused by the fluid administration but there is no difference between groups. However, in both adult and senile dogs, these variables recover gradually after the animals awaken, through increased urine production and recovery of vascular tonus, indicating the successful reestablishment of homeostasis.

Perioperative trends in plasma colloid osmotic pressure in horses undergoing surgery.

To compare perioperative trends in plasma colloid osmotic pressure (COP) between horses undergoing orthopedic and colic surgery. Prospective clinical study September 2009-January 2011. Veterinary university teaching hospital. Thirty-three healthy, client-owned horses presenting for orthopedic surgery (non-GI) and 85 client-owned horses presenting for emergency exploratory celiotomy (GI, gastrointestinal). None. Data relating to the horse's parameters on presentation, surgical lesion, post-operative management and survival were extracted from computerized clinical records. Heparinized blood samples were taken on presentation (PreOp, pre-operative), on recovery from anesthesia (T0), at 12 (T12) and 24 (T24) hours post recovery. COP was measured within 4 hours of collection. There was no significant difference in PreOp or T0 COP between groups. Both groups had a significant decrease in COP during anesthesia. When compared to their respective pre-operative values, horses in the non-GI group had significantly increased COP at T12, whereas those in the GI group had significantly reduced COP. This trend was continued at T24. Horses in the GI group placed on intravenous crystalloid isotonic fluids post-operatively had a significantly lower COP at T12 and T24. Horses in the GI group that did not survive had significantly lower post-operative COP values at T24. Horses undergoing exploratory celiotomy had significantly lower COP post-operatively than those horses undergoing orthopedic surgery. This difference was more marked in those horses receiving isotonic crystalloid intravenous fluid therapy post-operatively and in those that did not survive to discharge. In the non-GI group an increase in COP post-operatively was common.

Interstitial Fluid Colloid Osmotic Pressure in Healthy Children

ObjectiveThe colloid osmotic pressure (COP) of plasma and interstitial fluid play important roles in transvascular fluid exchange. COP values for monitoring fluid balance in healthy and sick children have not been established. This study set out to determine reference values of COP in healthy children.Materials and MethodsCOP in plasma and interstitial fluid harvested from nylon wicks was measured in 99 healthy children from 2 to 10 years of age. Nylon wicks were implanted subcutaneously in arm and leg while patients were sedated and intubated during a minor surgical procedure. COP was analyzed in a colloid osmometer designed for small fluid samples.ResultsThe mean plasma COP in all children was 25.6 ± 3.3 mmHg. Arbitrary division of children in four different age groups, showed no significant difference in plasma or interstitial fluid COP values for patients less than 8 years, whereas patients of 8-10 years had significant higher COP both in plasma and interstitial fluid. There were no gender difference or correlation between COP in interstitial fluid sampled from arm and leg and no significant effect on interstitial COP of gravity. Prolonged implantation time did not affect interstitial COP.ConclusionPlasma and interstitial COP in healthy children are comparable to adults and COP seems to increase with age in children. Knowledge of the interaction between colloid osmotic forces can be helpful in diseases associated with fluid imbalance and may be crucial in deciding different fluid treatment options.Trial RegistrationClinicalTrials.gov NCT01044641

Systemic inflammatory response during cardiac surgery: a pilot study.

There is a growing body of evidence indicating that perioperative fluid management during cardiac surgery influences patient care and outcome. The choice of fluid therapy and the degree of systemic inflammatory response triggered during surgery control the effects of tissue edema formation and end-organ function. As such, "goal-directed" fluid resuscitation protocols that measure colloid osmotic pressure (COP) may promote improvements in patient morbidity and mortality. Thirty patients scheduled for primary coronary artery bypass grafting were prospectively randomized for perioperative fluid treatment under COP guidance [albumin (ALB), n = 17] or conventional fluid protocols without COP support (control, n = 13). Whole-blood samples were drawn at four different time intervals including (A) anesthesia induction, (B) 10 minutes after the initiation of cardiopulmonary bypass, (C) at the completion of sternal skin approximation, and (D) 3 hours after admission to the cardiac intensive care unit. Interleukin 6 (IL-6) and IL-8 were measured by immunometric, enzyme-linked immunosorbent assays as well as C-reactive protein. Colloid osmotic pressure values were measured using a colloid osmometer. As compared with conventional fluid protocols, the patients treated in the intervention (ALB) group received significantly less total perioperative fluid [7893.6 (1874.5) vs 10,754.8 (2403.9), P = 0.001], and this relationship remained after controlling for age, sex, and The Society of Thoracic Surgeons risk score (β = -0.5, t = -3.1, P = 0.005). Colloid osmotic pressure values were significantly higher in the ALB group at time point D after surgery (P = 0.03). There were no significant differences in IL-6, IL-8, and C-reactive protein values between the groups at any of the time blood draw intervals. Perioperative outcomes were evaluated by treatment group. For both groups, the incidence of perioperative morbidity was low and did not differ by treatment group. The use of COP-guided fluid resuscitation was associated with a significant reduction in perioperative fluid demand. However, patients prescribed to COP-guided fluid therapy did not experience a reduction in whole-body inflammation or improved surgical outcome as compared with conventional fluid management techniques.

PO-0027 Interstitial Fluid Colloid Osmotic Pressure In Healthy Children

Background and aims Colloid osmotic pressure (COP) of plasma and interstitial fluid play important roles in transvascular fluid exchange were small pressure alterations may result in fluid shifts into or out of the capillaries optimising homeostasis. This study was conducted to determine reference values of COP in healthy children, and to evaluate the methodology of harvesting interstitial fluid. Methods COP in plasma and interstitial fluid isolated from nylon wicks implanted subcutaneously was measured in 99 healthy children from 2 to 10 years of age. Patients were sedated and intubated during wick implantation in arm and leg, and COP was analysed in a colloid osmometer. Results Mean plasma COP in all children was 25.6 ± 3.3 mmHg. Arbitrary division of children in age groups, showed no significant difference in plasma or interstitial fluid COP values for patients less than 8 years, whereas patients of 8–10 years had significant higher COP both in plasma and interstitial fluid. There was no gender difference or correlation between COP in interstitial fluid sampled from arm and leg and no significant effect on interstitial COP of gravity. Prolonged implantation time did not affect interstitial COP. Conclusions This study justifies the presumption that plasma and interstitial COP in healthy children are similar to adults. Children between 8 and 10 years had higher values than younger age groups. Knowledge of interaction between colloid osmotic forces in health and disease can be helpful in diseases associated with fluid imbalance and may be crucial in deciding different fluid treatment options.

Coagulation, oncotic and haemodilutional effects of a third‐generation hydroxyethyl starch (130/0.4) solution in horses

Clinical indications for hydroxyethyl starches (HES) in horses include rapid plasma volume expansion and oncotic support during periods of hypoproteinaemia. Side effects such as coagulopathies associated with HES administration pose limitations to their use in veterinary medicine. In man, tetrastarch (130/0.4) has demonstrated less profound effects on coagulation compared with first- and second-generation HES. To evaluate the haemostatic and oncotic effects of tetrastarch (130/0.4) administered at 10, 20 and 40 ml/kg bwt in healthy horses. Randomised crossover experiment. Tetrastarch (130/0.4) was administered to 6 healthy pony mares at 10, 20 and 40 ml/kg bwt with a 2-week washout period. Packed cell volume, plasma total solids, colloid osmotic pressure (COP), platelet count and thromboelastography (TEG) were measured at baseline, immediately after infusion (0 h), and 1, 6, 12, 24, 48 and 96 h after tetrastarch infusion. All TEG variables remained within normal reference ranges in all 3 treatment groups. Administration of tetrastarch at 40 ml/kg bwt resulted in a prolonged K-time (P = 0.049) at 6 h post infusion, and decreased maximum amplitude at 0 (P<0.001), 1 (P = 0.022), 6 (P = 0.006), 24 (P<0.001) and 48 h (P = 0.013) post infusion compared with baseline. Administration of tetrastarch increased mean COP values above baseline in all 3 treatment groups, persisting to 24, 6 and 48 h for the 10, 20 and 40 ml/kg bwt doses, respectively. Although still within established reference ranges, compared with lower dosages, the administration of 40 ml/kg bwt tetrastarch (130/0.4) is more likely to induce changes in coagulation as measured by TEG. Tetrastarch increased COP at all dosages evaluated in healthy horses. Tetrastarch (130/0.4) at 10 and 20 ml/kg bwt has potential as a synthetic colloid for resuscitation and provision of oncotic support in horses.

Method for Approximating Colloid Osmotic Pressure in Long‐Term Hemodialysis Patients

Colloid osmotic pressure (COP) is important in calculating vascular permeability during hemodialysis (HD). However, few reports have directly measured COP in HD patients. Therefore, the currently published formulas may not be clinically optimal for predicting COP for HD patients. Here, the study aims were (i) to directly measure COP in HD patients and compare the measured and predicted COP values using four previously reported formulas, and (ii) to develop a formula for approximating COP using clinical parameters. We obtained 212 measured COP values using an osmometer; the average value was 22.0 ± 0.2 mm Hg. The predicted COP based on the four different formulas was positively correlated with the measured COP (0.87 < r < 0.89), but was significantly overestimated compared to it (P < 0.001). We also performed a stepwise analysis using serum albumin and non-albumin protein concentrations and obtained the following simple formula for COP approximation: COP (mm Hg) = -7.91 + 5.64 × albumin (g/dL) + 3.00 × non-albumin proteins (g/dL). A positive linear correlation was observed between the measured COP and approximated COP using this formula (r = 0.90, P < 0.001). We calculated the mean Kr (plasma-refilling coefficient) as a marker for determining dry weight in HD patients using the measured COP and approximated COP. No differences were observed between the mean Kr derived from the measured and approximated COP. We report here significant differences between measured and predicted COP values, and have devised a simple formula for COP approximation in HD patients.

Comparison of whole blood and plasma colloid osmotic pressure in healthy dogs

To determine the difference between colloid osmotic pressure (COP) values determined from plasma versus those determined from whole blood. Prospective observational study. University veterinary teaching hospital. Fifty-three healthy dogs. None. Whole blood and plasma COP, CBC, plasma biochemistry. In all dogs, plasma COP values were significantly lower (P=0.02) than whole blood COP, with a mean of difference of 0.5 mm Hg. The mean and median whole blood COP was 21.75 and 21.4 mm Hg, respectively, with a range of 17.9-27.1 mm Hg. The mean and median plasma COP was 21.2 and 20.9 mm Hg with a range of 16.7-28.9 mm Hg. While significant difference exists between plasma and whole blood COP, the individual values are within expected reference intervals for dogs (21-25 mm Hg). Using either sample appears to provide the same information in clinically healthy dog; however, it is recommended that clinicians utilize the same sample type for comparison in an individual patient.

Ott's protein osmotic pressure of serum and interstitial fluid in chickens (Gallus gallus): effect of age and gender

Protein, or colloid, osmotic pressure (COP) is of sufficient magnitude to exert a powerful effect on Starling forces across the capillary wall. Although avian skin lacks active mechanisms for fluid transmission, such as sweating, it is now hypothesized that passive oncotic forces may regulate fluid flow and distribution in the skin and related phenomena. In this study, serum protein profiles, as well as COP in serum (COP(s)) and in suction blister fluid (COP(sbf)), were determined in juvenile, young and adult female and male chickens. For assessing COP, the Ott-Ahlqvist equation was applied. This equation can formulate the effects of multiple serum proteins on COP, according to their molecular mass. The COP values determined in chickens were lower than those previously found in mammals. COP(s) increased with age in males, and was higher in adult males than in adult females. In contrast, COP(sbf) decreased with age in females, although it was better preserved in adult males. The age-dependent decrease in COP was associated with a parallel decrease in the concentration of α(1)-globulin and albumin, and a positive correlation between packed cell volume (PCV) and COP was found. It is concluded that ageing affects Ott's COP around the vessel wall, and that an oncotic mechanism preserves plasma volume. The preservation of COP(sbf) in males suggests better maintenance of the interstitial ground substance. Females seem to lose more of a tissue's COP(s) counteracting force than males, probably as a result of gender-specific changes in the composition of the interstitial matrix. Further studies are required to elucidate the structure and function of avian lymphatics and their role in skin rheology.

Isolation of interstitial fluid from skeletal muscle and subcutis in mice using a wick method.

Until recent years, mice were sparsely used in physiological experiments, and therefore, data on the basic cardiovascular parameters of mice are lacking. Our aim was to gain access to interstitial fluid and thereby study transcapillary fluid dynamics in this species. Using a modified wick method, we were able to isolate interstitial fluid from subcutis and skeletal muscle in mice. Three-stranded, dry, nylon wicks were inserted post mortem in an attempt to avoid local inflammation and thus eliminate protein extravasation and wick contamination. Colloid osmotic pressure (COP) was measured with a colloid osmometer for submicroliter samples and averaged (means +/- SE) 18.7 +/- 0.4 in plasma, 9.1 +/- 0.4 in subcutis, and 12.3 +/- 0.5 mmHg in muscle. HPLC of plasma and wick fluid showed similar patterns except for some minor peaks eluting in the <40-kDa region. Plasma protein extravasation as determined by 125I-labeled human serum albumin showed that contamination of wick fluid by plasma proteins was negligible (<2%). Capillary hyperfiltration induced by intravenous infusion of saline (10% of body wt) was reflected in tissue fluid isolated by wicks as shown by the average postinfusion COP values of 14.5 +/- 0.6, 6.8 +/- 0.3, and 7.7 +/- 0.4 mmHg in plasma, subcutis, and muscle, respectively. We conclude that the wick technique can be easily adapted for use in mice and may represent a reliable method to isolate interstitial fluid and study transcapillary fluid flux in this species.

Measurement of plasma colloid osmotic pressure in neonatal foals under intensive care: comparison of direct and indirect methods and the association of COP with selected clinical and clinicopathologic variables

AbstractObjectives: To describe and compare admission colloid osmotic pressure (COP) measurement using both direct and indirect methods in neonatal foals under intensive care, and to evaluate for associations between COP and clinical/clinicopathologic parameters.Design: Prospective study.Setting: Intensive care unit at a veterinary medical teaching hospital.Animals: Twenty‐six critically ill neonatal foals were studied. A control group consisted of 9 clinically healthy neonatal foals.Interventions: Clinicopathologic data were collected at the time of admission. COP was measured directly using a colloid osmometer. Indirect COP was calculated using equations by both Landis–Pappenheimer (L–P) and Thomas and Brown.Measurements and main results: Measured admission COP values were 17.1±4.3 and 17.7±2.4 mmHg in critically ill and control foals, respectively, and these values were not significantly different. Critically ill foals with blood lactate concentrations &gt;3 mmol/L had lower COP values than those with lactate ≤3 mmol/L. There was close agreement between indirect COP values calculated using the L–P equation and direct COP values measured in control foals (mean error=0.0±1.3 mmHg; R2=0.87). However, indirect values were not as predictive of direct COP in critically ill foals (mean error=0.8±3.8 mmHg; R2=0.64). As COP values increased, the indirect method tended to overestimate COP, whereas at lower values it slightly underestimated COP.Conclusion: While the L–P equation was a close approximation of direct COP in healthy foals, direct measurements of oncotic pressure cannot be replaced for monitoring of critically ill foals. Critically ill foals with higher lactate concentrations had lower COP values, suggesting a possible relationship between COP and lactate.

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.

Continuous axial rotation and pulmonary fluid balance in acute lung injury

Objective: To investigate the effect of continuous axial rotation (CAR) treatment on the degree of pulmonary oedema (extravascular lung water [EVLW]) and arterial oxygenation in mechanically ventilated patients with acute lung injury (ALI). Design: Prospective investigation in a 12-bed intensive care unit (ICU) of a university hospital. Patients: Sixteen patients with ALI requiring mechanical ventilation. Methods: Random allocation into two groups. In the CAR group (n =8), patients were treated in a kinetic bed for a period of 72 h. In the control group (n =8), patients were treated in a 'conventional' bed. Intrathoracic blood volume (ITBV) and EVLW were assessed by the thermal dye dilution method at baseline (T0) and at 12, 24, 48, and 72 h after baseline. Additionally, arterial oxygenation, serum albumin levels and colloid osmotic pressure values in the serum were measured. Results: After 48 h of treatment, mean EVLW was significantly lower in the CAR group (6.3 ± 1.6 ml/kg [standard deviation, SD]), compared with the control group (11.2 ± 4.9 ml/kg) (p&lt;0.05). In the control group, EVLW tended to increase during the study period. Arterial oxygenation (PaO2/FIO2-ratio) improved continuously during axial rotation therapy and was significantly higher after 24 h of treatment compared with the control group (32 ± 7.5 kPa vs. 21.2 ± 6.6 kPa, p&lt;0.05, respectively). Serum albumin levels, ITBV, and colloid-osmotic pressures in the serum did not show any difference between the two groups during the experimental protocol. Conclusions: Continuous axial rotation caused a reduction of EVLW in patients with ALI. This may be due to continuous changes in intrathoracic pressures during kinetic therapy.

Continuous axial rotation and pulmonary fluid balance in acute lung injury

Objective: To investigate the effect of continuous axial rotation (CAR) treatment on the degree of pulmonary oedema (extravascular lung water [EVLW]) and arterial oxygenation in mechanically ventilated patients with acute lung injury (ALI). Design: Prospective investigation in a 12-bed intensive care unit (ICU) of a university hospital. Patients: Sixteen patients with ALI requiring mechanical ventilation. Methods: Random allocation into two groups. In the CAR group (n =8), patients were treated in a kinetic bed for a period of 72 h. In the control group (n =8), patients were treated in a 'conventional' bed. Intrathoracic blood volume (ITBV) and EVLW were assessed by the thermal dye dilution method at baseline (T0) and at 12, 24, 48, and 72 h after baseline. Additionally, arterial oxygenation, serum albumin levels and colloid osmotic pressure values in the serum were measured. Results: After 48 h of treatment, mean EVLW was significantly lower in the CAR group (6.3 ± 1.6 ml/kg [standard deviation, SD]), co...

Measurement of Plasma Colloid Osmotic Pressure in Normal Thoroughbred Neonatal Foals

A normal plasma colloid osmotic pressure (COP) interval was established for foals and compared to values for adult horses. Plasma samples were obtained from 38 Thoroughbred foals that had normal findings on postfoaling examination and 10 healthy Thoroughbred adult horses. Samples were analyzed using a commercially available colloid osmometer. Fifty samples were obtained from 38 foals. Twelve foals had 2 samples taken, 1 during the 1st 24 hours of life and the 2nd between 24 and 72 hours of life. For foals with 2 samples, only 1 randomly selected value was used in group analysis. Total plasma protein, albumin, and globulin concentrations were measured on all samples from foals. The mean measured plasma COP for foals was 18.8 ± 1.9 mm Hg for the 38 samples analyzed. Measured plasma COP did not differ significantly over the time period examined for either the 12 paired samples (P= .13) or with regression analysis of the 38 samples (P= .13). Calculation of mean COP, based on previously published quadratic equations using total protein, albumin, and globulin concentrations, underestimated mean measured foal COP values except for when total protein measured by refractometer was used in the Landis‐Pappenheimer equation. In conclusion, the plasma COP interval (95% CI: 15.0 mm Hg, 22.6 mm Hg) obtained for healthy foals in this study was found to be lower than that of healthy adult Thoroughbreds (20.6 ± 0.7 mm Hg, P= .006).

The risk of pulmonary edema and colloid osmotic pressure changes during magnesium sulfate infusion

The purposes of this study were to evaluate the effect of magnesium sulfate therapy on colloid osmotic pressure and to determine whether changes in colloid osmotic pressure increased the risk of pulmonary edema. During a 1-year time period 294 patients received parenteral magnesium sulfate for the treatment of preterm labor or preeclampsia. Both changes in colloid osmotic pressure and magnesium sulfate values and their relationship to clinical outcome parameters were analyzed. Serum magnesium levels were similar for both patients with preeclampsia and patients with preterm labor. Pulmonary edema developed in only four patients, all of whom had preeclampsia and low colloid osmotic pressure values. This study demonstrated that parenteral magnesium sulfate therapy does not cause significant changes in colloid osmotic pressure values until nearly 48 hours of continuous therapy.

Circadian Variations of Plasma Colloid Osmotic Pressure During the Third Trimester in Normal and Preeclamptic Pregnancies

The present study was performed to assess the changes of plasma colloid osmotic pressure (COP) in preeclampsia, and to clarify the character of circadian variations of plasma COP in preeclampsia. During the third trimester of a normal pregnancy, plasma COP values were 21.0 ± 0.2 at 28-31 weeks' gestation, 19.3 ± 0.5 at 32-35 weeks' gestation and 20.4 ± 0.5 mmHg at 36 weeks or more of gestation. These values were significantly lower than those in normal non-pregnant subjects (23.5 ± 0.6). In preeclampsia, plasma COP values (14.7 ± 0.4) were significantly lower than those in normal pregnancy. A circadian variation of plasma COP confirmed a clear circadian rhythm with the acrophase at afternoon in all subjects, and there were no differences among normal non-pregnant, pregnant and severe preeclamptic women. These results indicate that circadian variations of plasma COP are not influenced by either pregnancy or preeclampsia, though plasma COP in preeclampsia significantly decreases.

Low colloid osmotic pressure in very low birthweight infants receiving assisted ventilation.

Plasma colloid osmotic pressure (COP) was measured in three groups of very low birthweight infants. Babies in Group 1 (n = 8) were breathing spontaneously and had no respiratory disease. Those in Group 2 (n = 9) received assisted ventilation for hyaline membrane disease (HMD), and those in Group 3 (n = 7) received assisted ventilation for other reasons (five apnoea, two pneumonia). Both assisted ventilation groups had lower mean COP values than spontaneously breathing infants. Mean values (s.e.m.) for Groups 1, 2 and 3, respectively, were: 15.3 (0.6), 11.3 (0.4) and 11.9 mmHg (0.5) (P less than 0.001) on Day 1; and 15.2 (0.4), 12.9 (0.4) and 12.8 mmHg (0.3) (P less than 0.001) on Day 2. The increase from Day 1 to Day 2 was significant for those with HMD (P less than 0.05). Colloid osmotic pressure correlated with mean blood pressure (r = 0.51; P less than 0.001) but not with birthweight, gestation, crystalloid fluid intake or pH. The role of low COP in the pathogenesis of acute respiratory failure in infants with uncomplicated HMD is unclear, but such low COP may contribute to development of pulmonary oedema as a complication, particularly if the ductus arteriosus is still patent and the infants are given high volume intravenous fluids.