Noradrenaline: friend or foe?

Perioperative Fluid Management

The medical complexity of the geriatric patients has been steadily rising. Still, as outcomes of surgical procedures in the elderly are improving, centers are pushing boundaries. There is also a growing appreciation of the importance of perioperative fluid management on postoperative outcomes, especially in the elderly. Optimal fluid management in this cohort is challenging due to the combination of age-related physiological changes in organ function, increased comorbid burden, and larger fluid shifts during more complex surgical procedures. The current state-of-the-art approach to fluid management in the perioperative period is outlined.

Noradrenaline use for neonatal circulatory support

AIM

Noradrenaline (NA) has been used in preterm and term infants for circulatory support due to conditions including sepsis and pulmonary hypertension of the newborn. Treatment in neonates varies widely between institutions and respective neonatologists. The aim of this study is to determine the indications, use and effects of NA in preterm and term infants requiring circulatory support at the Royal Brisbane and Women's Hospital neonatal intensive care unit. We also aim to determine whether there were any differences between neonates who survived versus those who died after NA treatment.

METHODS

Data were collected from Royal Brisbane and Women's Hospital neonatal unit database including preterm and term infants between 1 January 2016 and 31 May 2021. Analysis included indication for use, blood pressure response, perfusion parameters, haemodynamic indicators and adverse effects.

RESULTS

NA treatment was documented in 37 patients requiring treatment of cardiovascular compromise. In 11 (30%) of these infants the indication for use was due to sepsis, 19 (51%) infants had pulmonary hypertension of the newborn, and 7 (19%) infants were diagnosed with hypotension prior to NA administration. Infants who subsequently died (49%) represented a younger gestational age population and exhibited worse cardiac compromise prior to NA administration. Tachycardia occurred in 15 (31%) infants and 1 (2.7%) infant developed transient hypertension. Overall improvement in poor tissue perfusion was seen after NA use.

CONCLUSION

NA use in treating neonates requiring circulatory support appears to be effective. Further prospective trials into NA use as a first- or second-line inotropic agent would be valuable.

Noradrenaline in preterm infants with cardiovascular compromise

Noradrenaline (NA) is beneficial in the treatment of term newborns with cardiovascular compromise due to sepsis or pulmonary hypertension, but experiences with NA in preterm infants are limited. The aim of this study is to describe the efficacy and safety of NA in preterm infants. Patient records of preterm infants ≤32 weeks' gestation admitted to two hospitals between 2004 and 2015 and who received NA were reviewed for perinatal morbidities and mortality. Clinical details were collected at the time of NA use, and response on blood pressure, perfusion and oxygenation was documented as well as possible side effects. Forty-eight infants with primary diagnoses of sepsis (63 %) and pulmonary hypertension (23 %) received NA. Normotension was achieved at a median of 1 h in all but one infant at a median dose of 0.5 mcg/kg/min. Infants who died (46 %) were of younger gestational age and had worse cardiovascular function at start of NA compared to infants who survived. Tachycardia was common (31 %), but no additional effects were found on kidney or liver function.

CONCLUSION

NA appears to be tolerated safely by preterm infants with no major side effects. However, effectiveness needs to be studies further in structured trials. What is Known: • Noradrenaline is beneficial in the treatment of term newborns and infants with cardiovascular compromise. • Noradrenaline is known for its potent vasoconstrictive effects and, therefore, infrequently used in preterm infants. What is New: • Noradrenaline used in relative low dose and as first or second line support increases blood pressure in preterm infants with cardiovascular compromise. • Tachycardia was common, but no additional side effects were found.

Clinical management for patients admitted to a critical care unit with severe sepsis or septic shock

BACKGROUND

The Surviving Sepsis Campaign promotes the use of norepinephrine as the first-line inotropic support for patients presenting with severe sepsis or septic shock in cases of persistent hypotension, despite adequate fluid resuscitation. However, there is little published evidence on how much noradrenaline is administered to such patients when admitted to the intensive care unit (ICU). The authors report the clinical management of this group of patients, with a special focus on the total amount and duration of norepinephrine infusion required.

METHODS

A chart review of the admission records of an ICU in Hong Kong was carried out in 2013. A total of 5000 patients were screened by their diagnosis of severe sepsis or septic shock (in the admissions book) between 1 January 2011 and 31 December 2013. A total of 150 of these were identified and 100 included in the study after simultaneous in-depth reviews of their case notes by two of the investigators. The analysis covers those with severe sepsis or septic shock who required ICU admission for further care. Clinical management and outcomes were analysed.

RESULTS

100 patients (median age 61.6; M/F ratio 2:1) met the inclusion criteria. The mean ICU stay was 13.4 days (range=1-371). 14 patients (14%) died in the ICU, with a 28-day mortality rate of 22%. The mean period of mechanical ventilation was 6.1 days (range=0-137). 91.5% (n=43) of patients had been operated on immediately before admission to the ICU, and the majority of these operations had been of the emergency type (97.7%, n=43). The mean total volumes of crystalloid and colloid administered were 3420ml and 478ml, respectively. The mean wean-off period for norepinephrine infusion was 4234minutes (70.5hours). All patients were prescribed norepinephrine for persistent hypotension despite adequate fluid resuscitation, and the mean total amount administered was 87,211mg. Final multiple linear and logistic regression analysis showed different clinical outcomes associated with different covariates, which included: (1) total amount of crystalloid given, positively associated with the total amount and duration of norepinephrine infusion; (2) duration of mechanical ventilation, positively associated with the type of operation the patient had undergone; (3) 28-day mortality rate, positively associated with the INR.

CONCLUSIONS

What this study adds to knowledge about patients suffering from severe sepsis or septic shock: (1) the mean duration of norepinephrine infusion for septic shock patients in an ICU is almost three days; (2) the more crystalloid is required to correct hypoperfusion, the higher the dosage and longer the duration of norepinephrine infusion will be necessary; (3) the longer the patient's INR, the higher the chances of death within 28 days. Since not all patients have their body weight measured on or after admission to the ICU, we suggest further research into indirect estimation of body weight by other means, such as anthropometric measures, to guide the use of drugs and nutritional support in the ICU. In addition, APACHE scores should be included in further studies to compare the severity of the patient's condition in other research. Furthermore, since this study does not cover university hospital ICUs, we suggest that further research concerning such patients should compare and reflect similarities and differences between public and university hospitals in the territory.

Norepinephrine increases blood pressure but not survival with anthrax lethal toxin in rats

OBJECTIVES

The response of anthrax lethal toxin (LeTx) induced shock and lethality to conventional therapies has received little study. Previously, fluids worsened outcome in LeTx-challenged rats in contrast to its benefit with lipopolysaccharide (LPS) or Escherichia coli. The current study investigated norepinephrine treatment.

MEASUREMENTS AND MAIN RESULTS

Sprague-Dawley rats (n = 232) weighing between 230 and 250 g were challenged with similar lethal (80%) 24-hour infusions of either LPS or LeTx, or with diluent only. Toxin-challenged animals were also randomized to receive 24-hour infusions with one of three doses of norepinephrine (0.03, 0.3, or 3.0 microg/kg/min) or placebo started 1 hour after initiation of challenge. All toxin animals received similar volumes of fluid over the 24 hours (equivalent to 4.0-4.3 mL/kg/hr). Although the intermediate norepinephrine dose (0.3 microg/kg/min for 24 hours) improved survival with LPS (p = 0.04) and increased blood pressure before the onset of lethality with LeTx (p < 0.0001), it did not improve survival with the latter (p = ns). Furthermore, neither increasing nor decreasing norepinephrine doses improved survival with LeTx.

CONCLUSION

Hypotension with LeTx may not be a primary cause of lethality in this model. Rather, LeTx may cause direct cellular injury insensitive to vasopressors. These findings suggest that during anthrax infection and shock, along with hemodynamic support, toxin-directed treatments may be necessary as well.

Modulation of aquaporin-2/vasopressin2 receptor kidney expression and tubular injury after endotoxin (lipopolysaccharide) challenge

OBJECTIVE

Sepsis-induced organ dysfunctions remain prevalent and account for >50% of intensive care unit admissions for acute renal failure with a mortality rate nearing 75%. In addition to the fact that the mechanisms underlying the pathophysiology of sepsis-related acute renal failure are unclear, the impact on septic-induced acute renal failure of either norepinephrine, a gold-standard vasopressor, and arginine vasopressin, a candidate alternative, are not well understood.

DESIGN

Randomized and controlled in vivo study.

SETTING

Research laboratory and animal facilities.

SUBJECTS

Adult rats treated with endotoxin (lipopolysaccharide) and/or vasopressors.

INTERVENTIONS

Rats were intraperitoneally injected with lipopolysaccharide (12 mg/kg) or saline and then infused with either saline, 0.375 microg/microL arginine vasopressin, or 32.5 microg/microL norepinephrine for 18 hrs. These vasopressor rates yielded respective targeted blood levels observed in human septic shock.

MEASUREMENTS AND MAIN RESULTS

Renal function, including glomerular filtration rate and fraction, renal blood flow, aquaporin-2, and arginine vasopressin-2 (V2 receptor) networking, water and salt handling, and urinary protein excretion, were evaluated. After lipopolysaccharide challenge arginine vasopressin infusion: 1) impaired creatinine clearance without affecting renal blood flow, glomerular filtration rate, and fraction but reduced free-water clearance, both of which being partially restored by the V2 receptor antagonist SR-121463B; 2) decreased the recognized ability of arginine vasopressin alone to recruit aquaporin-2 to the apical membrane increase its mRNA expression and urinary release; 3) increased urinary protein content but decreased specific kidney injury molecule-1, and Clara cell protein-16 release (p < 0.05 vs. lipopolysaccharide alone). Conversely, norepinephrine infusion did not add to lipopolysaccharide-induced alteration of urine biochemistry, except for improved creatinine clearance and increased microalbuminuria.

CONCLUSION

In this endotoxic model, dose-targeted arginine vasopressin infusion increased lipopolysaccharide-induced renal dysfunction without affecting renal blood flow and glomerular function, but with particular disruption of aquaporin-2/V2 receptor networking, consecutive decreased salt and water handling ability. This is in clear contrast with norepinephrine infusion and suggests specific arginine vasopressin-induced "tubular epithelial dysfunction."

SHORT-TERM EFFECTS OF PHENYLEPHRINE ON SYSTEMIC AND REGIONAL HEMODYNAMICS IN PATIENTS WITH SEPTIC SHOCK

Clinical studies evaluating the use of phenylephrine in septic shock are lacking. The present study was designed as a prospective, crossover pilot study to compare the effects of norepinephrine (NE) and phenylephrine on systemic and regional hemodynamics in patients with catecholamine-dependent septic shock. In 15 septic shock patients, NE (0.82 +/- 0.689 microg x kg(-1) x min(-1)) was replaced with phenylephrine (4.39 +/- 5.23 microg x kg(-1) x min(-1)) titrated to maintain MAP between 65 and 75 mmHg. After 8 h of phenylephrine infusion treatment was switched back to NE. Data from right heart catheterization, acid-base balance, thermo-dye dilution catheter, gastric tonometry, and renal function were obtained before, during, and after replacing NE with phenylephrine. Variables of systemic hemodynamics, global oxygen transport, and acid-base balance remained unchanged after replacing NE with phenylephrine except for a significant decrease in heart rate (phenylephrine, 89 +/- 18 vs. NE, 93 +/- 18 bpm; P < 0.05). However, plasma disappearance rate (phenylephrine, 13.5 +/- 7.1 vs. NE, 16.4 +/- 8.7% x min(-1)) and clearance of indocyanine green (phenylephrine, 330 +/- 197 vs. NE, 380 +/- 227 mL x min(-1) x m(-2)), as well as creatinine clearance (phenylephrine, 81.3 +/- 78.4 vs. NE, 94.3 +/- 93.5 mL x min(-1)) were significantly decreased by phenylephrine infusion (each P < 0.05). In addition, phenylephrine increased arterial lactate concentrations as compared with NE infusion (1.7 +/- 1.0 vs. 1.4 +/- 1.1 mM; P < 0.05). After switching back to NE, all variables returned to values obtained before phenylephrine infusion except creatinine clearance and gastric tonometry values. Our results suggest that for the same MAP, phenylephrine causes a more pronounced hepatosplanchnic vasoconstriction as compared with NE.