Differences In Acid-base Status Research Articles

Intraoperative goal-directed fluid therapy in neurosurgical patients: A systematic review.

Perioperative fluid management is critical in neurosurgery as over perfusion can lead to brain edema whereas under perfusion may lead to brain hypoperfusion or ischemia. We aimed to determine the effectiveness of intraoperative goal-directed fluid therapy (GDFT) in patients undergoing intracranial surgeries. We searched MEDLINE, Cochrane, and PubMed databases and forward-backward citations for studies published between database inception and February 22, 2024. Randomized controlled trials where intraoperative GDFT was performed in neurosurgery and compared to the conventional regime were included in the study. GDFT was compared with the conventional regime as per primary outcomes - total intraoperative fluid requirement, serum lactate, hemodynamics, brain relaxation, urine output, serum biochemistry, and secondary outcomes - intensive care unit and hospital length of stay. The quality of evidence was assessed with the Cochrane risk of bias tool. This study is registered on PROSPERO (CRD42024518816). Of 75 records identified, eight were eligible, the majority of which had a low to moderate risk of overall bias. In four studies, more fluid was given in the control group. No difference in postoperative lactate values was noted in 50% of studies. In the remaining 50%, lactate was more in the control group. Three out of four studies did not find any significant difference in the incidence of intraoperative hypotension, and four out of six studies did not find a significant difference in vasopressor requirement. The majority of studies did not show significant differences in urine output, brain relaxation, and length of stay between both groups. None found any difference in acid base status or electrolyte levels. GDFT, when compared to the conventional regime in neurosurgery, showed that the total volume of fluids administered was lesser in the GDFT group with no increase in serum lactate. There was no difference in the hemodynamics, urine output, brain relaxation, urine output, length of stay, and biochemical parameters.

Positive Effects of Pre-exercise Metabolic Alkalosis on Perceived Exertion and Post-exercise Squat Jump Performance in World-Class Cyclists.

Thomas, C, Delfour-Peyrethon, R, Dorel, S, and Hanon, C. Positive effects of pre-exercise metabolic alkalosis on perceived exertion and post-exercise squat jump performance in world-class cyclists. J Strength Cond Res 36(9): 2602-2609, 2022-This study aimed to determine the effects of pre-exercise alkalosis in world-class cyclists on their general (rate of perceived exertion [RPE]) and local (category-ratio scale [CR10]) perceived rates of exertion and acid-base status during 2 types of training sessions. Eight world-class cyclists ingested either sodium bicarbonate (BIC) or a placebo (PLA) in a double-blind and randomized order before performing 4 × 1,000 m constant-power sprints (CP) or 3 × 500 m all-out sprints (AO), with 20 minutes of recovery time between each session. For AO, the performance was assessed through the cycling sprint velocity and a squat jump test during recovery. During both tests, RPE, CR10, and acid-base status were measured. Sodium bicarbonate ingestion was effective in inducing pre-exercise alkalosis, compared with a PLA ( p < 0.05). During CP, performance and RPE were the same for BIC and PLA ( p > 0.05) with no time effect. The CR10 increased for the last sprint in PLA ( p < 0.05) but was attenuated in BIC (BIC: 6 vs. PLA: 8.2; p < 0.05), whereas there was no difference in acid-base status. During AO, RPE and CR10 increased with time, with no BIC effect, whereas blood lactate concentration was different ( p < 0.05). Sodium bicarbonate supplementation had no effect on overall repeated sprints ( p > 0.05). However, world-class athletes responded to BIC with higher squat jump performance than the PLA condition after AO ( p < 0.05). Our results suggest a positive influence of pre-exercise alkalosis in world-class cyclists on local perception of efforts after constant load sprints and an attenuation of muscle power output decline postsprint, as evidenced by improved squat jump performance after all-out cycling effort.

Comparison of Commercially Available Balanced Salt Solution and Ringer's Lactate on Extent of Correction of Metabolic Acidosis in Critically Ill Patients.

IntroductionAppropriate early fluid resuscitation is ubiquitous for critically ill patients with metabolic acidosis. Owing to harmful effects of normal saline, commercially prepared balanced salt solutions are being used. However, there is no study comparing use of Ringer's lactate (RL) and commercially available balanced salt solutions in critically ill patients.Materials and methodsA randomized controlled trial was conducted during July 2016 to December 2017. Fifty adult patients admitted to intensive care unit with metabolic acidosis were randomized into group RL or group acetate solution (AC). Respective trial fluid was administered at 20 mL/kg/hour for first hour and 10 mL/kg/hour for second hour. Arterial blood gas analysis samples were taken 15 minutes apart. The fluid resuscitation was continued till pH got corrected to 7.3 or 2 hours, whichever was earlier. The primary aim was to compare time to correct metabolic acidosis in both the groups. The secondary outcomes were the extent of correction of metabolic acidosis, total volume of fluid used, and total cost per patient.ResultsDemographic parameters, APACHE II score, and baseline investigations were comparable. The metabolic acidosis got corrected in 12 patients in group AC and 10 patients in group RL (p value = 0.66). The mean time for correction of metabolic acidosis was 57 ± 3.85 minutes in group RL and 56.25 ± 4.22 minutes in group AC (p value =0.95). The extent of correction of metabolic acidosis and total volume of fluid used was also comparable (p value = 0.05). However, the cost of fluid used was significantly higher in group AC (p value < 0.01).ConclusionDuring administration of balanced salt solutions, RL or AC, in critically ill patients with metabolic acidosis, AC did not confer any advantage in time to or extent of correction of metabolic acidosis.Clinical significanceThere is no difference in acid–base status with use of different types of balanced salt solutions for resuscitation in critically ill patients.How to cite this articleRawat N, Sahni N, Yaddanapudi L. Comparison of Commercially Available Balanced Salt Solution and Ringer's Lactate on Extent of Correction of Metabolic Acidosis in Critically Ill Patients. Indian J Crit Care Med 2020;24(7):539–543.

The differences in acid-base status and the calcium parathyroid axis between peritoneal dialysis and hemodialysis.

Several guidelines have set the target levels of serum Ca, phosphorus, and parathyroid hormone (PTH) for better management of chronic kidney disease-mineral and bone disorders (CKDMBD) in dialysis patients. Although serum ionized Ca (iCa) is a biologically active component, corrected Ca (cCa) is used in clinical settings. However, the association between iCa and cCa is affected by acid-base status. We investigated the difference in acid-base and the calcium-parathyroid status between hemodialysis (HD) and peritoneal dialysis (PD). The markers associated with CKD-MBD were measured in 142 patients receiving chronic dialysis (69 on PD and 73 on HD). Serum bicarbonate levels were significantly higher in the PD group than in the HD group (26.6 ± 2.8 vs. 22.9 ± 2.0 mEq/L, p < 0.01). The serum iCa levels and the iCa/cCa ratio were significantly lower in the PD group than in the HD group (iCa 1.07 ± 0.08 vs. 1.14 ± 0.08 mmol/L, p < 0.01; iCa/cCa ratio 45.5 ± 3.1% vs. 49.7 ± 3.2%, p < 0.01). The cCa levels were significantly higher in the PD group than in the HD group (9.4 ± 0.4 vs. 9.1 ± 0.4 mg/dL, p < 0.01). Intact PTH levels were significantly higher in the PD group than in the HD group (220 (40 - 581) vs. 133 (30 - 666) pg/mL, p < 0.01). We found that PD patients had lower iCa and higher PTH levels despite higher cCa levels as compared to HD patients. These results suggested that the assessment of both Ca and PTH should be different between PD and HD.

Greater Fatigue During Repeated-Sprint Exercise with Shortened Recovery is not Associated with Changes in Systemic Acid-Base Balance

Repeated-sprint activity leads to a decline in mechanical performance (power output), a phenomenon called muscle fatigue. Changes in acid-base status (i.e., metabolic acidosis) have previously been suggested to contribute to fatigue during repeated-sprint exercise. One way to test this hypothesis would be to determine if differences in fatigue, as a result of different repeated-sprint protocols, could be explained by differences in acid-base status. PURPOSE: The present study investigated the effects of varying the recovery time between consecutive sprints on repeated-sprint exercise performance and possible contributing mechanisms. METHODS: Eight young men completed two trials of 18, 4-s cycling sprints, in a random order, on two occasions. In one trial the exercise protocol consisted of 3 sets of 6 sprints separated by 20-s passive recovery intervals. Between each set of sprints subjects rested for 180 s (short recovery protocol; SRP). In the second trial, the exercise protocol consisted of 6 sets of 3 sprints, also separated by 20-s passive recovery intervals. Between each set of sprints subjects rested for 180 s (long recovery protocol; LRP). RESULTS: Relative to the first sprint, PPO decreased more during the SRP compared with LRP over the first 6 sprints (16.1% vs. 8.2%; P = 0.03), 12 sprints (19.4% vs. 11.8%; P = 0.05), and 18 sprints (23.3% vs. 11.7%; P = 0.004). Similarly, the decrease in TW was higher in SRP compared with LRP at any time point (10.1% – 12.6%; P = 0.01–0.003). Relative to the LRP, the SRP trial resulted in a substantial decrease in total work after sprint 6(−6.1%;P=0.002), sprint 12 (−6.2%; P=0.002) and sprint 18 (−7.4%; P=0.003). Despite these differences in repeated-sprint exercise performance, changes in blood acid-base status (pH, lactate, HCO3-), cardiovascular load (heart rate) and rating of perceived exertion (RPE) did not differ between the two conditions at any time point (i.e., rest, sprint 6, sprint 12 and sprint 18). CONCLUSION: Differences in repeated-sprint exercise performance, associated with the reduction of the available rest time between sprints, could not be explained by acute changes in systemic acid-base status.

Spinal and epidural versus general anesthesia for elective Cesarean section at term: effect on the acid–base status of the mother and newborn

Objective: To compare general, epidural and combined spinal-epidural anesthesia with respect to short-term outcome of newborns delivered by elective Cesarean section of healthy parturients with normalpregnancies.Study design: A total of 238 eight pregnant women admitted to our institution between January 1998 and July 2002, for whom elective Cesarean section was planned after 38 weeks' gestation,were grouped according to the kind of anesthesia used for the procedure. Maternal characteristics, birth weight, Apgar scores, and maternal and umbilical artery (UA) acid-base parameters were analyzed.Results: Maternal pH was significantly lower and pCO2 and pO2 were significantly higher in the general anesthetic group, compared to the other two groups (7.38± 0.03 vs. 7.43 ± 0.02 and 7.43 ± 0.05, respectively; 35.03 ± 3.88 mmHg vs. 29.25 ± 5.05 mmHg and 29.64 ± 4.16 mmHg, respectively; and 224.56 ± 86.77 mmHgvs. 151.28 ± 38 mmHg and 157.36 ± 53.51 mmHg, respectively, p < 0.05). The pH of the UA was higher in the general anesthetic group, compared to the spinal-epidural group (7.29 ±0.02 vs. 7.26 ± 0.06, p < 0.05). The pO2 as well as O2 saturation of the UA were higher when general anesthetic was administered, compared to the two regionalmodalities (15.60 ± 5.48 mmHg vs. 9.29 ± 4.41 mmHg and 9.20 ± 4.06 mmHg, respectively; and 17.37 ± 9.79% vs. 7.87 ± 4.98% and 6.90 ± 5.22%, respectively, p< 0.05). UA O2 saturation fell to zero in some cases in the combined spinal-epidural group, without an evident effect on fetal well-being. No fetal acidemia was noted in any group. Neonataloutcomes were similar in the three groups studied.Conclusions: Type of anesthesia does not influence short-term outcomes in infants born via elective Cesarean section, although differences inacid-base status of both the mother and especially the newborn recommend careful use of spinal anesthesia.

Relationship between the sonographic pattern of intrauterine growth restriction and acid-base status at the time of cordocentensis.

To determine whether there is a difference in acid-base status at the time of cordocentesis between fetuses with symmetric and asymmetric intrauterine growth restriction (IUGR). Non-anomalous singleton fetuses with IUGR who underwent fetal blood sampling for rapid karyotype analysis from 1992-1995 were retrospectively identified. Cases with gestational age <24 weeks, abnormal karyotype, or evidence of congenital infection were excluded. Fetuses were divided into two groups based on Head Circumference/ Abdominal Circumference Ratio (HC/AC). The asymmetric-IUGR group had HC/AC > or = 95% tile for GA, and the symmetric-IUGR group had HC/AC <95% tile. GA adjusted values of umbilical venous pH, pCO2, pO2, HCO3, hemoglobin and reticulocyte count were calculated by subtracting the mean values for GA from the observed and compared between groups. Both symmetric-IUGR (n = 7) and asymmetric-IUGR (n = 9) had umbilical venous pH and pO2, levels lower than GA normative values. However, there were no differences between groups for any of the parameters studied. Fetuses with symmetric and asymmetric IUGR due to UPI display a similar degree of acid-base impairment.

RESUSCITATION WITH LACTATED RINGERʼS SOLUTION AFTER HEMORRHAGE

The toxicity of D-lactate has been recognized for almost 30 years. This compound is found in the racemic mixture of lactated Ringer's solutions routinely used for peritoneal dialysis and the resuscitation of trauma victims. The current study was designed to investigate whether toxicity occurred at the D-lactate concentrations achieved during hemorrhage resuscitation with racemic lactated Ringer's solution. Conscious unrestrained male Sprague-Dawley rats (n = 24) were monitored for electrocardiographic abnormalities while undergoing hemorrhage and subsequent resuscitation with either L-lactated, D-lactated, or racemic lactated Ringer's solution. The rats infused with D-lactate showed significant toxicity as evidenced by bradycardia, premature ventricular contractions, and ventricular fibrillation. No such alterations were observed in the animals resuscitated with L-lactate or racemic solutions. Resuscitation with the racemic lactate mixture increased the D-lactate concentrations in the blood, but was not associated with overt changes in cardiac rhythm. The infusion of the different resuscitation fluids produced few significant differences in acid-base status of hemorrhaged rats. These findings indicate that although toxicity may be achieved with a Ringer's solution containing only D-lactate, resuscitation using the racemic mixture does not achieve D-lactate concentrations high enough to be detrimental to the animal.

Priming solutions for cardiopulmonary bypass: Comparison of three colloids

The present study was designed to compare the differences in the clinical effects of three colloidal solutions, albumin, urea-linked gelatin, and succinyl-linked gelatin, when used as priming fluids for cardiopulmonary bypass (CPB) under α-stat conditions. A consecutive series of 105 patients scheduled for cardiac surgery were randomized into three identically managed groups, except for the CPB prime. Variables relating to acid-base status, oncotic activity, metabolism, coagulation, and postoperative evaluation were measured. Marked differences in acid-base status, colloid osmotic pressure, additional prime requirements, blood lactate, urine output, and the need for buffer solutions occurred among groups, with the succinyl-linked gelatin group having better results than the other groups. Changes in hemodynamics, oxygen consumption, and blood-glucose levels during CPB did not vary among groups. There were also no important intergroup differences in hematologic and clotting variables or postoperative parameters such as blood loss or use of blood products. Electrolyte changes were similar except for a significant increase in ionized calcium that occurred in the urea-linked gelatin group after bypass. The results indicate that succinyl-linked gelatin is an adequate and safe alternative to human albumin for use as a colloid during CPB under α-stat conditions.

Assessing Acid-Base Status in Circulatory Failure

To assess arteriovenous differences in acid-base status, we measured the pH and partial pressure of carbon dioxide (PCO2) in blood drawn simultaneously from the arterial and central venous circulations in 26 patients with normal cardiac output, 36 patients with moderate and 5 patients with severe circulatory failure, and 38 patients with cardiac or cardiorespiratory arrest. The patients with normal cardiac output had the expected arteriovenous differences: venous pH was lower by 0.03 unit, and venous PCO2 was higher by 0.8 kPa (5.7 mm Hg). These differences widened only slightly in those with moderate cardiac failure. Additional simultaneous determinations in mixed venous blood from pulmonary arterial catheters were nearly identical to those in central venous blood. In the five hypotensive patients with severe circulatory failure there were substantial differences between the mean arterial and central venous pH (7.31 vs. 7.21) and PCO2 (5.8 vs. 9.0 kPa [44 vs. 68 mm Hg]). Large arteriovenous differences were present during cardiac arrest in patients whose ventilation was mechanically sustained, whether sodium bicarbonate had been administered (pH, 7.27 vs. 7.07; PCO2, 5.8 vs. 8.6 kPa [44 vs. 65 mm Hg]) or not (pH, 7.36 vs. 7.01; PCO2, 3.7 vs. 10.2 kPa [28 vs. 76 mm Hg]). By contrast, in patients with cardiorespiratory arrest, large arteriovenous differences were noted only when sodium bicarbonate had been given (pH, 7.24 vs. 7.01; PCO2, 9.5 vs. 16.9 kPa [71 vs. 127 mm Hg]). We conclude that both arterial and central venous blood samples are needed to assess acid-base status in patients with critical hemodynamic compromise. Although information about arterial blood gases is needed to assess pulmonary gas exchange, in the presence of severe hypoperfusion, the hypercapnia and acidemia at the level of the tissues are detected better in central venous blood.

Monensin level during grain adaptation and finishing performance in cattle.

Two finishing trials were conducted to measure the response of cattle adjusting to high-concentrate diets to dietary monensin level. In trial 1, 54 individually fed Hereford-Angus steers (312 kg), previously fed a two-thirds corn silage: one-third corncob-based diet, were allotted in a 2 X 3 factorial arrangement of treatment with tylosin (0, 11 mg/kg) and monesin (0, 11, 33 mg/kg) fed during a 28-d, grain-adaptation period (fed 75% concentrate for 6 d and then fed 95% concentrate). After 28 d, all steers were continued on their respective levels of tylosin and 33 mg/kg monensin for the remaining 119 d. Daily intake patterns indicated digestive upset in all treatments during adjustment to the 95%-concentrate diet. Blood samples taken during the first 28 d revealed no differences in acid-base status in response to monensin level; however, all steers exhibited reduced (P less than .01) pH and HCO3 and increased (P less than .01) lactate after 4 d on a 75%-concentrate diet. In the initial 28 d, intake decreased (linear P less than .05) as the level of monensin increased. In the total finishing period, however, increasing the level of monensin fed during grain adaptation decreased (linear P less than .05) intake and tended to decrease (linear P = .20) gain with no effect on feed efficiency.(ABSTRACT TRUNCATED AT 250 WORDS)

Acid-Base Status of Diabetic Mothers and Their Infants following Spinal Anesthesia for Cesarean Section

Pregnancy in the diabetic patient is associated with increased hazard to mother and fetus. Cesarean section is frequently required in this high-risk group. The present authors, in a previous investigation, noticed lower umbilical pH values in infants of diabetic mothers having spinal anesthesia for cesarean section than in infants whose diabetic mothers received general anesthesia (7.20 vs. 7.28). The study reported here was designed to assess the effectiveness of the following measures in the administration of spinal anesthesia: 1) strict regulation of maternal blood glucose levels to maintain them between 80 and 90 mg/dl, 2) acute intravenous volume loading immediately before the induction of spinal anesthesia with a dextrose-free solution, and 3) avoidance of maternal hypotension during anesthesia. The purpose of such measures was to improve the neonatal acid-base values in this special group of patients. Twenty parturients scheduled for elective primary or repeat cesarean section at term were selected at random. Ten were controlled insulin-dependent diabetic mothers (mean preoperative fasting blood glucose level, 86 ± 4 mg/dl). The other 10 were healthy nondiabetic women who served as control patients. Two diabetic parturients were hospitalized three weeks before delivery for control of fasting blood glucose levels. Before surgery, however, fasting blood glucose levels were within normal limits (86 ± 4 mg/dl) in all the diabetic mothers. Comparison of the two groups of mothers revealed no significant differences in maternal age, height, or gestational age. Systolic blood pressure did not exceed 130 torr in any parturient within 24 hours of operation, and none of the mothers had systolic pressures of more than 30 torr from baseline levels during anesthesia. The total amount of ephedrine administered varied from 10 to 30 mg and was not significantly different between the two groups. There were no differences in the induction-delivery or uterine incision-delivery intervals between the two groups. The acid-base status of the mothers in both groups was normal at delivery. There were no significant differences in acid-base status or in blood-gas tensions between infants in the control and in the diabetic groups. Only one baby in the diabetic group had an Apgar score of less than 7 at one minute; the rest had Apgar scores greater than 7 at both one and five minutes. The authors observed that strict control of maternal diabetes, avoidance of dextrose-containing solutions for acute maternal volume expansion before anesthesia, and prompt treatment of any decrease of maternal blood pressure will maintain neonatal acid-base status at control levels during spinal anesthesia and avoid the development of acidemia.

Respiration and Acid-Base Physiology of the Spotted Gar, A Bimodal Breather

ABSTRACT In normally aerated water, at 20 °C, gar accounted for 42 % of their MO2 from their lungs, while in hypoxic water (PO2≃ 12 torr) their entire MO2 was from the lung, and O2 was lost through the gills. CO2 excretion in both normoxia and hypoxia was primarily via the gills. Lung ventilation increased 1150%, accompanied by an elevation of pulmonary perfusion from 5·9 to 12·1 ml · kg−1 · min−1 in hypoxia, which accounts for the enhanced pulmonary MO2. Cardiac output increased from 31 to 40·5 ml · kg−1 · min−1 and systemic perfusion was maintained in hypoxia. The difference in acid-base status between pre-and post-branchial blood (PCO2, pH and total CO2), changed only slightly during hypoxia, but the oxygen difference reversed. Normal dorsal aortic (DA) PCO2 was 23·8 torr, ventral aortic (VA) 20·3; during aquatic hypoxia the mean values were 21·9 and 22·6, respectively. Blood pressure rose in both the VA and DA in hypoxia but the branchial vascular resistance did not change. The oxygen transfer factor did not change significantly between normoxia and hypoxia. Anatomical studies of the gill microvasculature revealed a reduced and channelized lamellar circulation. No respiratory shunt pathways were found around the lamellae. The physiological and anatomical data indicated that the gar did not change lamellar perfusion or use shunt pathways to avoid hypoxic O2 loss.

The effects of deep hypothermia and circulatory arrest on systemic metabolic state of infants undergoing corrective open heart surgery: a comparison of two methods.

Fortyone of 187 infants undergoing corrective surgery for their congenital cardiac lesions using profound hypothermic circulatory arrest were randomly selected for metabolic studies. Deep hypothermia of 21 to 22 degrees C core temperature was reached by two different techniques: 1. Perfusion cooling by extracorporeal circulation (ECC-C) 2. Surface cooling with ice bags combined with perfusion cooling (SC + ECC-C) After circulatory arrest (34.2 min. ECC-C v.s. 46.7 min. SC + ECC-C) bypass rewarming was used in both groups. The metabolic reaction to these interventions are described. No significant differences in acid base status in oxygen consumption, lactate concentration, serum electrolytes (K+, Na+, Ca++,Cl-) and serum enzyme activity (CPK, alpha-HBDH, LDH, SGOT, SGPT) could be demonstrated between the two groups of patients during the entire course of cooling, circulatory arrest and rewarming. The glucose concentration was significantly lower in the ECC-C group during the entire period of operation. Total cooling time was significantly shorter in the group without surface cooling. (ECC-C: 12 min, v.s. SC + ECC-C: 64 min). Since no favourable effects of the SC + ECC-C method on systemic metabolism could be demonstrated and operative results were similar we now prefer the time-saving ECC-C technique.

RELATION OF INTRAVENTRICULAR HAEMORRHAGE TO HYALINE MEMBRANE DISEASE IN NEWBORN INFANTS

Using our perinatal data bank, clinical and pathological data on 104 sigleton infants who died with germinal layer haemorrhage and intraventricular haemorrhage /IVH/ at Hammersmith were analyzed in comparison with data from babies dying of other conditions, and with the background population. Of 31 cases of IVH without hyaline membrane disease /HMD/ only four infants were born at a gestation of 30 weeks or more, whereas in 73 cases of IVH with HMD 49 were born at over 30 weeks gestation. At all gestations infants who died with HMD + IVH had received more intense alkali therapy than those who died with HMD alone, although there was no difference in acid-base status or PaO2 measurements. Administration of alkali /THAM and bicarbonate/ in excess of 8 mEq/Kg body weight over any 12 hour period was significantly associated with the development of IVH. In babies of 30 weeks gestation or less the association between IVH and alkali therapy was significant whereas the association with HMD was not. It is suggested that the expansion of blood volume caused by administration of hypertonic solutions for treatment of HMD may be a significant factor in the causation of IVH.

RELATION OF INTRAVENTRICULAR HAEMORRHAGE TO HYALINE MEMBRANE DISEASE IN NEWBORN INFANTS

Using our perinatal data bank, clinical and pathological data on 104 sigleton infants who died with germinal layer haemorrhage and intraventricular haemorrhage /IVH/ at Hammersmith were analyzed in comparison with data from babies dying of other conditions, and with the background population. Of 31 cases of IVH without hyaline membrane disease /HMD/ only four infants were born at a gestation of 30 weeks or more, whereas in 73 cases of IVH with HMD 49 were born at over 30 weeks gestation. At all gestations infants who died with HMD + IVH had received more intense alkali therapy than those who died with HMD alone, although there was no difference in acid-base status or PaO2 measurements. Administration of alkali /THAM and bicarbonate/ in excess of 8 mEq/Kg body weight over any 12 hour period was significantly associated with the development of IVH. In babies of 30 weeks gestation or less the association between IVH and alkali therapy was significant whereas the association with HMD was not. It is suggested that the expansion of blood volume caused by administration of hypertonic solutions for treatment of HMD may be a significant factor in the causation of IVH.

ACID-BASE STATUS IN DIETARY TREATMENT OF PHENYLKETONURIA

Blood acid-base status, serum electrolytes, and urine pH were examined in 64 infants and children with phenylketonuria (PKU) treated with three different low phenylalanine protein hydrolyzates (Aponti, Cymogran, AlbumaidXP) and two synthetic amino acid mixtures (Aminogran, PAM). The formulas caused significant differences in acid-base status, serum potassium, and chloride, and in urine pH. In acid-base balance studies in two patients with PKU, Aponti, PAM, and two modifications of PAM (P2 + P3) were given. We observed a change from mild alkalosis to increasing metabolic acidosis from Aponti (serum bicarbonate 25,8 mval/liter) to P3 (24,0Y, P2 (19, 3) and PAM (17,0). Urine pH decreased and renal net acid excretion increased. In the formulas PAM, P2 and P3 differences in renal net acid excretion correlated with differences in chloride and sulfur contents of the diets and of the urines. New modifications of AlbumaidXP and of PAM, prepared according to our recommendations, showed normal renal net acid excretion (1 mEq/kg/24 hr) in a balance study performed in one patient with PKU and normal acid base status in 20 further patients.