Urine Output Rate Research Articles

Restoration of renal function in shock by perfusion of the renal artery with venous blood: a counterintuitive approach.

Acute renal failure (ARF) in low-flow states may be reversed by increasing renal perfusion. When hemodynamics are maximized, renal perfusion can only be improved by shunting a higher proportion of cardiac output to the kidney; however, in low-flow states, this reduces already compromised systemic pressure and perfusion to other organs. Increasing perfusion using venous blood (VB) would be an attractive option because decreased systemic pressure and perfusion to other organs could be avoided. However, it is not known whether VB can provide adequate oxygen delivery to restore or maintain renal function. We studied whether antegrade VB perfusion of the kidney via the renal artery would restore urine output (UO) and glomerular filtration rate (GFR) in hypoperfused ARF. Shock was induced in six dogs via a hemorrhagic protocol resulting in a systolic blood pressure of 50-70 mm Hg, a mixed venous oxygen saturation of 25% to 40%, and a UO <10% of baseline. After 60 mins of shock, the left renal artery was cannulated under fluoroscopy and perfused at pressures of 100-150 mm Hg for 30 mins with VB drawn from the vena cava and delivered by an extracorporeal pump system. The right kidneys were controls and remained hypoperfused. All VB-perfused kidneys recovered renal function after a sustained period of shock and marked oliguria: UO from 0.7 +/- 1.6 mL/hr to 101 +/- 58 mL/hr (p <.01); GFR from approximately 0 to 70.3 +/- 55 mL/min (p =.04). The control kidneys' UO (0.7 +/- 1.6 mL/hr) and GFR (0 mL/min) remained unchanged throughout the study. The experimental kidneys were able to extract oxygen from VB (O2 saturation, 31 +/- 7% to 16 +/- 4%; p =.01). When flow is controlled, kidneys in hypoperfused ARF can extract sufficient oxygen from antegrade VB perfusion to restore renal function (UO and GFR).

Pathophysiology and treatment of enuresis in adults.

Monosymptomatic nocturnal enuresis (MNE) in children is partly the result of inadequate reduction in the rate of urine output at night. This nocturnal polyuria is due to the lack of a rise in the anti-diuretic hormone, arginine vasopressin (AVP), and can be reduced or eliminated by treatment with desmopressin at bedtime. Since there is a 1% incidence of MNE among adults, this study investigated the circadian pattern of solute and water balance in nine young adult enuretics before and during desmopressin therapy and compared the results with nine-age- and sex-matched, healthy controls. Before treatment, enuretics and controls had similar total fluid intake, urine output, urine osmolality, plasma osmolality, plasma total protein, mean arterial pressure and plasma AVP. The circadian pattern of fluid intake was also normal in enuretics. This abnormality could not be attributed to a deficiency of plasma AVP or an increase in solute excretion, since both variables were similar to controls. Rather, their nocturnal polyuria appeared to be due to a marked nocturnal reduction in renal sensitivity to the antidiuretic effect of vasopressin. In seven enuretics, restudied during treatment with desmopressin (10-30 micrograms o.d.), circadian urine output was normal and enuresis was absent. These results indicate that: (i) The circadian pattern of urine output in healthy adults is largely due to a nocturnal decrease in solute excretion rather than a rise in plasma AVP; (ii) The subset of adults with persistent MNE also have nocturnal polyuria as a result of insensitivity to the antidiuretic action of AVP; (iii) These defects can be corrected by treatment with desmopressin.

Anti-diuresis in the blood-feeding insect Rhodnius prolixus Stål: the peptide CAP2b and cyclic GMP inhibit Malpighian tubule fluid secretion.

Rhodnius prolixus eliminates NaCl-rich urine at high rates following its infrequent but massive blood meals. This diuresis involves stimulation of Malpighian tubule fluid secretion by diuretic hormones released in response to distention of the abdomen during feeding. The precipitous decline in urine flow that occurs several hours after feeding has been thought until now to result from a decline in diuretic hormone release. We suggest here that insect cardioacceleratory peptide 2b (CAP2b) and cyclic GMP are part of a novel mechanism of anti-diuresis. Secretion rates of 5-hydroxytryptamine-stimulated Malpighian tubules are reduced by low doses of CAP2b or cyclic GMP. Maximal secretion rates are restored by exposing tubules to 1 mmol l-1 cyclic AMP. Levels of cyclic GMP in isolated tubules increase in response to CAP2b, consistent with a role for cyclic GMP as an intracellular second messenger. Levels of cyclic GMP in tubules also increase as urine output rates decline in vivo, suggesting a physiological role for this nucleotide in the termination of diuresis.

Oliguria during laparoscopic surgery.

Oliguria is infrequently viewed as a complication of laparoscopic surgery. The rate of urine output in six healthy patients undergoing laparoscopic surgery was measured during the period of CO2 pneumoperitoneum and for several hours after desufflation. The average hourly urine output during insufflation was 0.30 +/- 0.14 mL/kg despite an average hourly intravenous infusion rate of lactated Ringer's solution of 13.0 +/- 4.0 mL/kg. After release of pneumoperitoneum, urine output increased 467% to 1.7 +/- 1.1 mL/kg per hour. Patients remained hemodynamically unchanged perioperatively. Preoperative and postoperative blood urea nitrogen and creatinine concentrations did not significantly differ. We discuss the potential etiologic factors in the development of oliguria in the setting of the increased intra-abdominal pressure of pneumoperitoneum and the implications of this acute but reversible renal dysfunction.

Renal effects of multiple infusion of pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP) solution in dogs.

Pyridoxalated-hemoglobin-polyoxyethylene conjugate (PHP), which is made from out-dated human red blood cells by two major chemical modifications, namely pyridoxalation and conjugation with polyoxyethylene (POE), is currently under development as a physiological oxygen carrier. This study assessed the effects of PHP-88 solution, which contains 8% (wt/vol) each of hemoglobin (Hb) and maltose, on renal function when it was infused 3 times every other day into the intact circulation of 8 dogs (5 dogs for the PHP group and 3 for the control group; 20 ml/kg for the first infusion, and 10 ml/kg each for the second and third infusions, at the rate of 2.5 ml/h/kg). Serial determinations of glomerular filtration rate (GFR) and renal plasma flow (RPF) were carried out pre- and postinfusion for up to 3 months along with measurements of blood and urine analyses, urine output rate, fractional excretion of sodium (FES), and free water clearance (CH2O). The results showed that plasma colloid osmotic pressure (COP) elevated an average of 3.3 mm Hg (p = 0.0085), and GFR and RPF tended to increase by 13% (NS) and 38% (NS), respectively, immediately after the third infusion with PHP solution. Urine output rate increased during and after the infusion, and FES and CH2O also increased for 24 h after the infusion in both groups. Blood urea nitrogen, serum creatinine, and serum Na+ concentrations were not affected greatly by the infusions, but hematocrit was decreased by 8% in the PHP group, indicating approximately a 42% expansion of plasma volume. These changes were observed to return to their preinfusion levels by 1 week postinfusion. Renal histology of the PHP group obtained at 2 weeks postinfusion revealed vacuole formation in the proximal tubules which was not associated with any pathologic changes indicative of cell death or regeneration. In 4 out of 5 dogs at 3 months postinfusion (necropsy), the vacuoles were not present. Though urinary N-acetyl-beta-glucosaminidase (NAG) activity had significantly increased after infusion, it returned to the preinfusion level by 1 month postinfusion. No detrimental effect of vacuoles on the assessed renal tubular functions was confirmed in the present study. The results demonstrated that multiple infusions of PHP solutions were well tolerated in normal dogs, and the observed effects were conceived predominantly attributable to the physiological response of the kidneys to an oncotic load into the circulation, which produced plasma volume expansion.

Plasma Fluoride Concentrations During and After Prolonged Anesthesia

Serum inorganic fluoride concentrations were studied in 19 adult patients undergoing prolonged head and neck surgery with either halothane or isoflurane anesthesia (mean 19.5 and 19.2 MAC-hours, respectively). In the group of nine patients anesthetized with isoflurane, plasma inorganic fluoride increased from a mean concentration of 3.5 mumols/L (baseline) to a peak of 43.2 mumols/L. Forty percent of the patients in the isoflurane group had peak plasma inorganic fluoride concentrations of more than 50 mumol/L. In the group that received halothane, plasma inorganic fluoride concentrations increased from a mean of 3.8 mumols/L to a peak of 12.6 mumols/L. Despite similar exposures to both anesthetics, the differences in serum inorganic fluoride concentrations between the two groups were significant at 10, 24, and 48 h after induction of anesthesia (P = 0.035, P = 0.003, and P = 0.003, respectively). Serum electrolyte, urea, and creatinine concentrations and urine output rates during and after surgery were similar in both groups. We conclude that, after anesthesia of up to 20 MAC-hours, metabolism of isoflurane to inorganic fluoride may be of a greater magnitude than has previously been realized. Although no clinical or biochemical evidence was found to suggest postoperative renal dysfunction, we recommend caution using isoflurane when prolonged anesthesia and surgery are planned.

The effect of alpha-2 agonists and antagonists on the upper urinary tract of the rat.

We examined the effect of the selective alpha-2 agonist dexmedetomidine and antagonist atipamizole on the upper urinary tract, renal pelvic pressure and ureteral peristalsis. Experiments were performed on twelve Sprague-Dawley female rats weighing 275-323 grams, with administration of urethane (1.2 micrograms/kg). Ventilatory support was provided through a tracheotomy. A continuous normal saline infusion was maintained through the left iliac vein at a rate of 2.5 ml/hr. Arterial pressure was measured at the left iliac artery, which was cannulated with a PE-100 tube connected to a pressure transducer. A mid-line incision was then made from the xyphoid to the symphysis to expose the left kidney, both ureters, and the bladder. The bladder was intubated and drained to avoid bladder pressure increase. Measurements of urine output rate were made from the right ureter and renal pelvic or ureteral pressure was measured using a nephrostomy placed into the pelvis. A ureterostomy was produced by introducing another catheter, into the upper segment of the left ureter for ureteral pressure measurements. The rats were divided into two groups as follows: 1) dexmedetomidine group (n = 6); injected intravenously with 2 micrograms/kg of dexmedetomidine dissolved in 0.5 ml saline. 2) atipamizole group (n = 6); injected intravenously with 2 micrograms/kg of atipamizole dissolved in 0.5 ml saline. Ureteral peristaltic frequency, baseline pressure, and contraction amplitude were compared before, after, and between the bolus injections of 2 micrograms/kg dexmedetomidine (n = 6) or 2 micrograms/kg atipamizole (n = 6) in 0.5 ml saline. The results showed that dexmedetomidine at 2 micrograms/kg produced a significant decrease in arterial pressure and an increase in urine output from 1.2 + 0.8 to 3.6 + 1.2 ml/min. There was no effect on the baseline pelvic pressure of 6.8 + 1.2 cmH2O or amplitude of the renal pelvic contractions: 3.5 + 0.6 cmH2O. The frequency of pelvic contractions was reduced from 0.37 + 0.03 to 0.27 + 0.02 Hz. Atipamizole at 2 micrograms/kg produced a significant reduction in urine flow rate of 1.1 + 0.8 to 0.6 + 0.2 ml/min. Atipamizole also showed no significant effects on baseline pelvic pressure or frequency, but increased the amplitude of pelvic contractions from control values of 3.0 + 0.9 to 3.4 + 0.9 cmH2O. Dexmedetomidine reduced both the baseline ureteral pressure of 8.5 + 2.4 and peristaltic contraction pressure of 11.5 + 2.3 cmH2O in 4/6 rats. Atipamizole reduced base-line ureteral pressure and increased peristaltic rate.(ABSTRACT TRUNCATED AT 400 WORDS)

ISOFLURANE SEDATION FOR PATIENTS UNDERGOING MECHANICAL VENTILATION: METABOLISM TO INORGANIC FLUORIDE AND RENAL EFFECTS

The metabolism and renal effects of isoflurane sedation were studied for 24 h in patients undergoing mechanical ventilation. Forty-six patients admitted to our intensive therapy unit were allocated randomly to receive either 0.1-0.6% isoflurane or midazolam 0.01-0.2 mg kg-1 h-1 for sedation. In 26 patients sedated with isoflurane, plasma inorganic fluoride increased from a mean concentration of 4.03 mumol litre-1 to 13.57 mumol litre-1 12 h after stopping sedation. Plasma inorganic fluoride concentrations in 20 patients sedated with midazolam were unchanged from baseline values (mean 5.32 mumol litre-1). Serum electrolyte, urea and creatinine concentrations, and urine output rates during and after sedation in patients who received isoflurane were similar to those who received midazolam. We conclude that, following isoflurane sedation for up to 24 h, metabolism to inorganic fluoride is insufficient to cause clinical renal dysfunction.

Renal Response to Furosemide in Very Low Birth Weight Infants during Chronic Administration

Renal response to furosemide following initial and chronic doses was investigated in premature infants with bronchopulmonary dysplasia. Seven infants (mean birth weight = 890 +/- 216 g, mean gestational age at birth = 27.7 +/- 2.6 weeks, mean postnatal age at the start of diuretic therapy = 2.7 +/- 0.9 weeks) were studied. Twelve-hour urine collections were performed after the initial dose, and following chronic doses after 1 week and 3 weeks of therapy. Volume of each urine sample was measured and concentrations of furosemide, sodium and creatinine determined. Linear dose-response relationships were found between the logarithm of the urinary furosemide excretion rate and diuretic/natriuretic response (urine output and urinary sodium excretion rate). The furosemide excretion rate required to achieve midrange diuretic and natriuretic responses was significantly greater during chronic dosing than following initial doses, indicating a decrease in renal responsiveness to drug with sustained use. Increasing postconceptional age was associated with a decrease in initial responsiveness to furosemide. These data demonstrate that in premature infants renal sensitivity to furosemide decreases with chronic use as well as with increasing postconceptional age at the start of therapy. The decrease in renal sensitivity to drug with chronic use is of much greater magnitude, and appears to represent renal compensation for drug-induced diuresis and natriuresis.

Effect of low-dose dopamine infusion on urinary prostaglandin E2 excretion in sick, preterm infants.

In pharmacological doses dopamine (DA) will interact with several endocrine systems and both inhibit (prolactin, thyrotropin) and enhance (renin, angiotensin) hormonal release. In this study we have examined whether DA given to preterm neonates will influence prostaglandin (PG) production. The question is of importance since vasodilator PGs play a role in postnatal adaptation. We determined the effect of low dose DA infusion on the 24 h urinary PGE2 excretion rate (an index of renal PGE2 synthesis) in preterm infants. Six preterm neonates, with a 24-h requirement of 2 micrograms/kg per min DA treatment for oedema, moderate oliguria, poor peripheral perfusion and/or mild systemic hypotension were studied on days 2 (Day 1), 3 (Day 2, the day of DA infusion), and 4 (Day 3, DA discontinued) of life. Six preterm infants (control group) that did not require DA infusion were also studied to monitor possible spontaneous changes in the renal PGE2 production on days 2, 3 and 4 of life. In the control group urine output (Uv) and PGE2 excretion rate remained unchanged during the study. In the study group DA administration resulted in nearly two-fold increases in both the Uv (194%) and PGE2 excretion (182%). Urinary PGE2 excretion was, however, closely related to urine flow in both the control infants (Day 1-3) and the study group infants (Day 1-2). Since increased diuresis stimulates renal PGE2 production, our data suggest that the increased PGE2 excretion on Day 2 in the study group was not due to a direct effect of DA on PGE2 synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)

EFFECTS OF HALOTHANE AND SODIUM NITROPRUSSIDE ON RENAL FUNCTION AND AUTOREGULATION

The effects of sodium nitroprusside and halothane on renal autoregulation and kidney function were studied in 14 mongrel dogs at mean arterial pressures of 120, 100, 80, 60 and 40 mm Hg. In group 1, stepwise decreases in mean arterial pressure were achieved by increasing the halothane concentration. In group II, mean arterial pressure was decreased by infusing sodium nitroprusside during halothane anaesthesia. In group I, renal blood flow decreased significantly at mean arterial pressures of 100, 80, 60 and 40 mm Hg. In group II, renal blood flow was well maintained at mean arterial pressures of 100 and 80 mm Hg, but decreased significantly at 60 and 40 mm Hg; at these low pressures flow was greater in group II than in group I. There were no significant differences between two groups in inulin clearance, inulin clearance/renal plasma flow, urine output, urine osmolarity and sodium excretion rate. Significantly larger fractions of cardiac output were distributed to the kidneys in group I.

Experimental assessment of prostacyclin in the harvesting of kidneys for transplantation.

Prostacyclin is a potent vasodilator and the most potent inhibitor of platelet aggregation yet discovered. A possible role for prostacyclin in the harvesting of kidneys in experimental canine transplantation has been investigated. Prostacyclin gives a 52.6% increase in renal blood flow prenephrectomy despite inducing a 23% drop in mean arterial blood pressure, without changing the rate of urine output. There is an associated drop in renal vascular resistance of 50.2% and an increase in renal blood volume of 25%. The value of heparin treatment before donor nephrectomy is confirmed as it improves the flow of flushing solution through the kidney after nephrectomy and improves red blood cell washout from the kidney. Prostacyclin and heparin together improve these parameters further. After a warm ischemic period of 45 min, autotransplanted kidneys in dogs pretreated with prostacyclin had normal renal function within 48 hr as judged by the serum creatinine whereas untreated dogs had permanent impairment of function.

Attenuation of pilocarpine-induced drinking by chronic treatment with estrogens.

SummaryAcute ip administration of graded doses of the parasympathomimetic agent, pilocarpine, to female rats increased their water intake, urine output and urinary sodium excretion rate in a graded...

Effect of chronic treatment with estrogen on the dipsogenic response of rats to angiotensin

Female rats treated with estradiol benzoate for 23 weeks at doses of 25 and 44 μg/kg/day had an attenuated drinking response to peripheral administration of graded doses of angiotensin I and angiotensin II. No significant difference between the responses of the two estrogen-treated groups was observed, suggesting that maximal attenuation had been attained with the lower dose. Angiotensin II (50, 100 and 200 μg/kg, IP) increased urine output and urinary sodium excretion rate in a graded fashion with increasing doses in both control and estrogen-treated rats. However, the latter had a somewhat greater response. Administration of angiotensin I (50, 100 and 200 μg/kg, SC) had a similar, but less consistent, effect on urine output and urinary sodium excretion rate in both control and estrogen-treated groups. The attenuated drinking response of estrogen-treated rats to angiotensin I and angiotensin II suggests either that administered angiotensin failed to gain access to the brain or that central receptors mediating thirst are less sensitive in estrogen-treated rats. The present studies fail to distinguish between these possibilities.

THE EFFECTS OF KETAMINE AND INNOVAR ON THE RENAL CORTICAL AND MEDULLARY BLOOD FLOW OF THE DOG

To study the effects of Ketamine and Innovar on renal function, the renal cortical and medullary blood flows of dog were measured using a thermo-electrical flowmeter, along with the urine output, blood pressure and pulse rate. Ketamine decreased the renal cortical blood flow and the urine output. Innovar increased the renal cortical blood flow, but did not alter the medullary blood flow appreciably, and decreased the urine output. Neither of these variations in renal blood flows ran parallel with variations in the arterial pressure nor did variations in the urine output run parallel with those in the blood flows. All anaesthetic agents are inhibitory to kidney, but Innovar may be preferred to other anaesthetics in view of the finding that the renal blood flows are well maintained even under anaesthesia with this agent.

Renal and extrarenal hemodynamic effects of furosemide in congestive heart failure after acute myocardial infarction

Abstract Furosemide, 0.5 to 1.0 mg per kilogram intravenously, was given to 20 patients with left ventricular failure after acute myocardial infarction. Within five to 15 minutes, average left ventricular filling pressure fell from 20.4 to 14.8 mm Hg, accompanied by a 52 per cent increase in mean calf venous capacitance. During the same period there was no physiologically important change in either urine output or heart rate, blood pressure and cardiac output. Peak increase in urine flow (from mean of 0.82 to 4.0 ml per minute) occurred at 30 minutes, and peak natriuretic effect at 60 minutes. Thus, the action of furosemide in the treatment of pulmonary congestion is immediate and is not related to its diuretic properties. Rather, the prompt fall in left ventricular filling pressure probably is primarily vascular in origin, since marked changes in venous capacitance accompany this phenomenon, which is only later supplemented by the increase in urine output and electrolyte excretion. (N Engl J Med 288:1087...

Renal and extrarenal hemodynamic effects of furosemide in congestive heart failure after acute myocardial infarction.

Abstract Furosemide, 0.5 to 1.0 mg per kilogram intravenously, was given to 20 patients with left ventricular failure after acute myocardial infarction. Within five to 15 minutes, average left ventricular filling pressure fell from 20.4 to 14.8 mm Hg, accompanied by a 52 per cent increase in mean calf venous capacitance. During the same period there was no physiologically important change in either urine output or heart rate, blood pressure and cardiac output. Peak increase in urine flow (from mean of 0.82 to 4.0 ml per minute) occurred at 30 minutes, and peak natriuretic effect at 60 minutes. Thus, the action of furosemide in the treatment of pulmonary congestion is immediate and is not related to its diuretic properties. Rather, the prompt fall in left ventricular filling pressure probably is primarily vascular in origin, since marked changes in venous capacitance accompany this phenomenon, which is only later supplemented by the increase in urine output and electrolyte excretion. (N Engl J Med 288:1087...

Water and electrolyte composition of the body and renal function of the eel ( Anguilla anguilla L.)

1. 1. The water, sodium, potassium and chloride contents of serum and muscle of yellow and silver eels ( Anguilla anguilla L.) in fresh water and sea water are given, together with urine output and glomerular filtration rates. ∗ Ion concentrations m-moles/kg tissue H 2O Type of eel Freshwater Seawater Na + K + Cl − Na + K + Cl − Serum ∗ ∗ m-moles/1. 155 2·7 106 178 2·8 155 Parietal muscle 30·4 110·1 35·0 124·7 “Tongue” muscle 41·9 112·6 47·9 121·7 Urine ∗ 18·9 0·65 Nil 6·5 2·08 119·4 2. 2. The results are discussed in relationship to the general problem of the adaptation of vertebrates to water of differing tonicity.

犬における頸部自家移植腎の研究

The function of the autotransplanted neck kidney for 3 hours after transplantation were examined by measuring renal clearance and renal extraction ratio.The results were as follows:(1) The transplanted kidney began to function shortly after the operation and the renal function was restored considerably within a few hours.(2) Urinary secretion from the transplanted kidney was perceptible after the operation within a half on an average 26.5 minutes.The rate of urine output was 0.067 to 1.87cc/min, the specific gravity ranged 1010 to 1028 and the reaction of the urine was alkalin. Though the urine secretion is the most important of the renal function, we cannot justly appreciate the renal function only by the rate of secretion.(3) The renal blood flow was severely impaired in the transplanted kidney. It amounted only 60% of the normal value 3 hours after the transplantation, even in the most favorable cases. The tubular function was damaged, also. In the favorable cases EPAH was 80% of the normal value. The impairment of glomerular function was minimum, as a normal measurement was obtained in the favorable cases.(4) Such renal damages may be due to unavoidable renal anoxia during the procedures of transplantation, duration of which lasted 43.0 minutes on an average. Anastomotical techniques of the blood vessels and denervation may be the contributory factors to the renal damages.(5) These results indicate that the homotransplantation of the kidney is clinically applicable.