The effect of NaCl 0.9% and NaCl 0.45% on sodium, chloride, and acid-base balance in a PICU population / Efeito do NaCl a 0,9% e do NaCl a 0,45% sobre o sódio, cloreto e equilíbrio ácido-base em uma população de UTIP

ABSTRACT OBJECTIVES: To study the effect of two intravenous maintenance fluids on plasma sodium (Na), and acid-base balance in pediatric intensive care patients during the first 24 h of hospitalization. METHODS: A prospective randomized controlled study was performed, which allocated 233 patients to groups: (A) NaCl 0.9% or (B) NaCl 0.45%. Patients were aged 1 day to 18 years, had normal electrolyte concentrations, and suffered an acute insult (medical/surgical). Main outcome measured: change in plasma sodium. Parametric tests: t-tests, ANOVA, X 2 statistical significance level was set at a = 0.05. RESULTS: Group A (n = 130): serum Na increased by 2.91 (±3.9) mmol/L at 24 h (p < 0.01); 2% patients had Na higher than 150 mmol/L. Mean urinary Na: 106.6 (±56.8) mmol/L. No change in pH at 0 and 24 h. Group B (n = 103): serum Na did not display statistically significant changes. Fifteen percent of the patients had Na < 135 mmol/L at 24 h. The two fluids had different effects on respiratory and post-operative situations. CONCLUSIONS: The use of saline 0.9% was associated with a lower incidence of electrolyte disturbances.

RESUMO OBJETIVO: Estudar o efeito de dois fluidos de manutenção intravenosos sobre o sódio (Na) plasmático e o equilíbrio ácido-base em pacientes de terapia intensiva pediátrica durante as primeiras 24 horas de internação. MÉTODOS: Foi feito um estudo controlado randomizado prospectivo. Alocamos aleatoriamente 233 pacientes para os grupos: (A) NaCl a 0,9% e (B) NaCl a 0,45%. Os pacientes com um dia a 18 anos apresentavam concentrações normais de eletrólitos e sofriam de insulto agudo (médico/cirúrgico). Principal resultado: variação no sódio plasmático. Testes paramétricos: teste t, Anova, qui-quadrado. O nível de relevância estatística foi estabelecido em a = 0,05. RESULTADOS: Grupo A (n = 130): o Na sérico aumentou 2,91 (± 3,9) mmol L-1 em 24 h (p < 0,01); 2% dos pacientes apresentaram Na acima de 150 mmol L-1. Concentração média de Na na urina: 106,6 (± 56,8) mmol L-1. Sem alteração no pH em 0 e 24 horas. Grupo B (n = 103): o Na sérico não apresentou alterações estatisticamente significativas; 15% dos pacientes apresentaram Na < 135 mmol L-1 em 24 h. Os dois fluidos tiveram efeitos diferentes sobre as situações respiratória e pós-operatória. CONCLUSÃO: O uso de solução fisiológica a 0,9% foi associado à menor incidência de distúrbios eletrolíticos.

Impact of Plasma-Lyte pH 7.4 on acid-base status and hemodynamics in a model of controlled hemorrhagic shock

OBJECTIVE: Intravenous infusion of crystalloid solutions is a cornerstone of the treatment of hemorrhagic shock. However, crystalloid solutions can have variable metabolic acid-base effects, perpetuating or even aggravating shock-induced metabolic acidosis. The aim of this study was to compare, in a controlled volume-driven porcine model of hemorrhagic shock, the effects of three different crystalloid solutions on the hemodynamics and acid-base balance. METHODS: Controlled hemorrhagic shock (40 percent of the total blood volume was removed) was induced in 18 animals, which were then treated with normal saline (0.9 percent NaCl), Lactated Ringer's Solution or Plasma-Lyte pH 7.4, in a blinded fashion (n = 6 for each group). Using a predefined protocol, the animals received three times the volume of blood removed. RESULTS: The three different crystalloid infusions were equally capable of reversing the hemorrhage-induced low cardiac output and anuria. The Lactated Ringer's Solution and Plasma-Lyte pH 7.4 infusions resulted in an increased standard base excess and a decreased serum chloride level, whereas treatment with normal saline resulted in a decreased standard base excess and an increased serum chloride level. The Plasma-Lyte pH 7.4 infusions did not change the level of the unmeasured anions. CONCLUSION: Although the three tested crystalloid solutions were equally able to attenuate the hemodynamic and tissue perfusion disturbances, only the normal saline induced hyperchloremia and metabolic acidosis.

Effect of chloride dialysate concentration on metabolic acidosis in aintenance hemodialysis patients

Hyperchloremia is one of the multiple etiologies of metabolic acidosis in hemodialysis (HD) patients. The aim of the present study was to determine the influence of chloride dialysate on metabolic acidosis control in this population. We enrolled 30 patients in maintenance HD program with a standard base excess (SBE) ≤2 mEq/L and urine output of less than 100 mL/24 h. The patients underwent dialysis three times per week with a chloride dialysate concentration of 111 mEq/L for 4 weeks, and thereafter with a chloride dialysate concentration of 107 mEq/L for the next 4 weeks. Arterial blood was drawn immediately before the second dialysis session of the week at the end of each phase, and the Stewart physicochemical approach was applied. The strong ion gap (SIG) decreased (from 7.5 ± 2.0 to 6.2 ± 1.9 mEq/L, P = 0.006) and the standard base excess (SBE) increased after the use of 107 mEq/L chloride dialysate (from -6.64 ± 1.7 to -4.73 ± 1.9 mEq/L, P < 0.0001). ∆SBE was inversely correlated with ∆SIG during the phases of the study (Pearson r = -0.684, P < 0.0001) and there was no correlation with ∆chloride. When we applied the Stewart model, we demonstrated that the lower concentration of chloride dialysate interfered with the control of metabolic acidosis in HD patients, surprisingly, through the effect on unmeasured anions.

Experimental antegrade enema: effects on water, electrolyte and acid-base balances with different solutions

PURPOSE: To study the effects on the water, electrolyte, and acid-base balances in rabbits submitted to antegrade enema with different solutions through appendicostomy. METHODS: Forty male New Zealand rabbits were submitted to appendicostomy, and distributed in 4 groups, according to the antegrade enema solution: PEG group, polyethylene glycol electrolyte solution (n=10); ISS group, isotonic saline solution (n=10); GS group, glycerin solution (n=10); SPS group, sodium phosphate solution (n=10). After being weighed, arterial blood gas analysis, red blood count, creatinine and electrolytes were measured at 4 times: preoperatively (T1); day 6 postop, before enema (T2); 4h after enema (T3); and 24h after T3 (T4). RESULTS: In PEG group occurred Na retention after 4h, causing alkalemia, sustained for 24h with HCO3 retention. In ISS group occurred isotonic water retention and hyperchloremic acidosis after 4h, which was partially compensated in 24h. GS group showed metabolic acidosis after 4h, compensated in 24h. In SPS group occurred hypernatremic dehydration, metabolic acidosis in 4h, and hypokalemia, hypocalcemia, hypomagnesemia, and metabolic alkalosis with partially compensated dehydration in 24h. CONCLUSIONS: All solutions used in this study caused minor alterations on water, electrolyte or acid-base balances. The most intense ones were caused by hypertonic sodium phosphate solution (SPS) and isotonic saline solution (ISS) and the least by polyethyleneglycol electrolyte solution (PEG) and glycerin solution 12 percent (GS).

OBJETIVO: Estudar os efeitos no equilíbrio hídrico, eletrolítico e ácido-base, do enema anterógrado com diferentes soluções em coelhos através de apendicostomia. MÉTODOS: 40 coelhos Nova Zelândia, machos, submetidos a apendicostomia, distribuídos em quatro grupos segundo a solução de enema: grupo PEG (n = 10) solução de polietilenoglicol com eletrólitos; grupo SF (n = 10) solução fisiológica; grupo SG (n = 10) solução glicerinada; grupo FS (n = 10) solução de fosfato de sódio. Realizou-se pesagem, gasometria arterial, série vermelha, creatinina e ionograma, em quatro tempos: TI (pré-operatório); T2 (6o PO antes do enema); T3 (4h após enema); T4 (24h após T3). RESULTADOS: No PEG ocorreu retenção de Na em 4h, com alcalemia por retenção de HCO3, mantida por 24h. No SF ocorreu retenção hídrica isotônica e acidose hiperclorêmica em 4h, resolvidos parcialmente com 24h. No SG ocorreu acidose metabólica hiperclorêmica em 4h, compensada com 24h. No FS ocorreu desidratação hipenatrêmica, acidose metabólica com ânion gap elevado em 4h, hipopotassemia, hipocalcemia, hipomagnesemia e alcalose metabólica com recuperação parcial da desidratação em 24h. CONCLUSÕES: Todas as soluções empregadas neste estudo causam alterações de pouca intensidade no equilíbrio hídrico, eletrolítico ou ácido-base. As mais intensas foram causadas pela solução de fosfato de sódio e solução fisiológica, e as menos intensas pela solução de polietilenoglicol com eletrólitos e solução glicerinada.

Antiretroviral agents and acid-base balance at delivery of the neonate

Limited evidence is available regarding antiretroviral (ARV) safety for uninfected infants exposed to these drugs in utero. Our objective was to determine if ARV administered to pregnant women is associated with decreasing umbilical arterial pH and base excess in uninfected infants. A prospective study was conducted on 57 neonates divided into three groups: ZDV group, born to mothers taking zidovudine (N = 20), triple therapy (TT) group, born to mothers taking zidovudine + lamivudine + nelfinavir (N = 25), and control group (N = 12), born to uninfected mothers. Umbilical cord blood was used to determine umbilical artery gases. A test was performed to calculate the sample by comparing means by the unpaired one-tailed t-test, with a = 0.05 and ß = 20 percent, indicating the need for a sample of 18 newborn infants for the study groups to detect differences higher than 20 percent. The control and ARV groups were similar in gestational age, birth weight, and Apgar scores. Values of pH, pCO2, bicarbonate, and base excess in cord arterial blood obtained at delivery from the newborns exposed to TT were 7.23, 43.2 mmHg, 19.5 mEq/L, and -8.5 nmol/L, respectively, with no significant difference compared to the control and ZDV groups. We conclude that intrauterine exposure to ARV is not associated with a pathological decrease in umbilical arterial pH or base excess. While our data are reassuring, follow-up is still limited and needs to be continued into adulthood because of the possible potential for adverse effects of triple antiretroviral agents.

Anesthesia for caesarean section and immediate neonatal outcome.

Seventy-eight parturient mothers undergoing elective caesarean section were studied with regard to the immediate neonatal outcome in those receiving general and spinal anesthesia. All mothers were of grade I anesthesia risk, were term and had singleton appropriate for gestational age babies. There was no difference in fetal acid base chemistry in the two groups. Babies delivered after general anesthesia appeared relatively depressed requiring more free flow oxygen and bag and mask ventilation though one minute Apgar scores showed no significant difference in either group. Induction delivery intervals were longer in the spinal group but it was not associated with more morbidity. Uterine incision delivery intervals were very small in both groups and no meaningful conclusion could be drawn as regards effect on the newborn. A plea is made for more frequent use of spinal anesthesia considering its many postnatal advantages.

Neonatal effects of anesthesia for caesarean section.

Seventy eight parturient mothers undergoing elective caesarean section were studied with regard to the immediate neonatal outcome in those receiving general and spinal anesthesia. All mothers were of grade I anesthesia risk, were term and had singleton appropriate for gestational age fetuses. There was no difference in fetal acid base chemistry in the two groups. Babies delivered after general anesthesia appeared relatively depressed requiring more free flow oxygen and bag and mask ventilation, though one minute Apgar scores showed no significant difference in either group. Induction delivery intervals were longer in the spinal group but it was not associated with more morbidity. Uterine incision delivery intervals were very small in both groups and no meaningful conclusion could be drawn as regards effect on the newborn. A plea is made for more frequent use of spinal anesthesia considering its many postnatal advantages.

The changes in electrolytes and acid-base balance after artificially induced acute diarrhea by laxatives

Following the acute diarrhea in patients (n = 24) overnight with commonly used laxatives for bowel preparation, the changes in electrolytes and acid-base balance in blood and urine were investigated. Though no alterations of serum sodium or potassium concentrations were noted, mild but significant reduction of mean values (+/- SEM) of plasma pH and HCO3 after diarrhea when compared to those before it developed (pH, from 7.42 +/- 0.01 to 7.39 +/- 0.01, p<0.01; HCO3, from 25.8 +/- 0.6 to 23.7 +/- 0.6 mEq/L, p<0.05). However, significant reduction of concentration in spot urine sodium from 150 +/- 12.3 to 93 +/- 14 mEq/g of crea. (p<0.01) and increase in spot urine potassium from 33 +/- 3.2 to 51 +/- 6.0 mEq/g of crea. (p<0.05) following diarrhea were seen with significant reduction of urine pH from 6.67 +/- 0.21 to 5.5 +/- 0.13 (p<0.001). Also, with this effective urinary acidification following diarrhea, a significant reduction of urinary anion gap as well as significant increment of spot urine ammonium was accompanied (anion gap, from 80.4 +/- 11.1 to 44 +/- 8.5 mEq/g of crea. p<0.001; ammonium, from 87 +/- 18.5 to 229 +/- 37 mg/g of crea. p<0.001) in addition to the significant inverse correlation between these changes in spot urine from basal levels in 24 study subjects (y = -1.13 x +61, r = 0.7, p<0.001). In conclusion, we observed that the acute diarrhea with laxatives used for bowel preparation caused a mild degree of metabolic acidosis with no changes in blood electrolytes.

Comparison of effects of naloxone and catecholamines on acid-base balance in canine hemorrhagic shock.

The present study was conducted to compare the effect of naloxone, an opiate receptor antagonist, with catecholamines on acid-base status and survival in dogs subjected to hemorrhagic shock. Arterial lactic acid concentration which had increased during hemorrhage, decreased significantly (P less than 0.05) in naloxone treated animals but increased further in catecholamine treated dogs. Blood bicarbonate concentration and PCO2 which had markedly decreased 1 hr after hemorrhage recovered significantly (P less than 0.05) in naloxone group of animals. On the other hand bicarbonate and pH declined further in noradrenaline group and remained unchanged in dopamine group. These results as well as better survival rate observed in naloxone treated animals suggest the superiority of naloxone over dopamine and noradrenaline, as an adjunct to blood transfusion in the treatment of hemorrhagic shock.

Alteraçöes do equilíbrio ácido-básico e hidrelectrolítico em cäes submetidos a hipercapnia / Changes in the acid base and water-electrolyte equilibrium in dogs subjected to hypercapnia

Foram estudadas as alteraçöes do equilíbrio ácido-básico e hidroeletrolítico em 12 cäes submetidos a hipercapnia com diferentes níveis de CO2 na mistura inalada (10% e 15%). Foram analisados os seguintes parâmetros pH sangüíneo, pressäo parcial de gás carbônico no sangue arterial, pressäo parcial de oxigênio no sangue arterial, bicarbonato de sódio plasmático, sódio plasmático, potássio plasmático, volume urinário, excreçäo urinária de sódio, excreçäo fracionária de sódio, depuraçäo de sódio, reabsorçäo de sódio, excreçäo urinária de potássio, excreçäo fracionária de potássio, depuraçäo de postássio, osmolaridade urinária, depuraçäo osmolar e depuraçäo de água livre. Os valores de pH sangüíneo apresentam uma queda significativa, tendendo a retornar aos níveis iniciais no fim do experimento. O bicarbonato plasmático e a diurese aumentam significativamente quando a concentraçäo inspirada de CO2 é de 15%. Ocorre tendência à queda da excreçäo urinária de sódio, na excreçäo fracionária de sódio e na depuraçäo de sódio e, contrariamente, uma tendência a aumento na reabsorçäo de sódio. Com a excreçäo fracionária e com a depuraçäo de potássio ocorre tendência a queda. Os parâmetros restantes näo apresentam variaçöes significantes. É ainda discutida a fisiopatologia das alteraçöes observadas em cada parâmetro estudado

Efeito da quetamina no equilíbrio ácido-base / Effect of Ketamine in acid-base balance

Os autores estudaram os efeitos da quetamina (6 mg. kg-1) como dose inicial e a seguir, (0,3 mg. kg-1) sobre o equilíbrio ácido-básico em 10 cäes. A investigaçäo foi complementada com a determinaçäo da excreçäo urinária de amônia (UNH4 V) e da acidez titulável da urina (ACTu). Os estudos foram feitos em quatro momentos: M1 - Controle (antes do uso de quetamina); M2 - Imediatamente após a anestesia com quetamina; M3 - 15 minutos após o início da anestesia; M4 - 45 minutos após o início da anestesia. Os resultados mostraram: a quetamina näo alterou o pH arterial (pHa), o pH venoso (pHv), a pressäo parcial de O2 do sangue arterial (PaO2), a pressäo parcial de O2 do sangue venoso (PvO2), a pressäo parcial de CO2 do sangue arterial (PaCO2), a pressäo parcial de CO2 do sangue venoso (PvCO2), a saturaçäo arterial de oxigênio (SaO2), o sódio plasmático (Nap), o potássio plasmático (Kp), o déficit de base (DB) e o bicarbonato plasmático (HC03p); aumenta a freqüência cardíaca (FC) e a pressäo arterial média (PAM); produziu queda do débito urinário (DU), da pressäo venosa periférica (PVP), da excreçäo urinária de sódio (UNa V), da excreçäo urinária de potássio (UK V), da excreçäo urinária de amônia (UNH4 V) e da acidez titulável da urina (ACTu). Demonstrou-se que o uso de quetamina em cäes diminui a excreçäo de ácidos fixos do organismo, embora näo alterarem aparentemente no equilíbrio ácido-base

Modificaciones del estado ácido-base del líquido cefalorraquídeo por efecto de la administración de alcalinizantes (bicarbonato de sodio y THAM) / Changes of the acid-base equilibrium of the cerebrospinal fluid by effect of administration of alkaline agents (sodium bicarbonate and THAM)

Cuando se infunde bicarbonato de sodio intravenoso el propósito de corregir la acidosis metabólica se obtienen resultados opuestos en el líquido cefalorraquídeo. La caída del pH en el líquido y, por lo tanto, en el sistema nervioso central, puede ocasionar empeoramiento en el estado de conciencia, modificación de la ventilación y modificación de la perfusión cerebral. Por el contrario, la infusión de THAM - Tris(hidroximetil)aminometano-, modifica en el mismo sentido el estado ácido-base en sangre, líquido cefalorraquídeo y, por lo tanto, en sistema nervioso central, logrando el objetivo de corregir la acidosis, sin introducir secuelas neurológicas. Para demostrar lo expuesto anteriormente, se trabajó con dos grupos de perros que fueron anestesiados y ventilados mecánicamente. A un grupo se le infundió bicarbonato de sodio intravenoso y al otro THAM por la misma vía. Se midieron los siguientes parámetros ácido-base en sangre arterial, venosa y líquido cefalorraquídeo; pH, presión parcial de dióxido de carbono, bicarbonato real, exceso de bases y THAM en el líquido, con un método que desarrollamos para tal fin