Too slow and too high

A 77-year-old woman on metoprolol and lisinopril presented to an emergency department with giddiness after vomiting for few hours. She was found to have low blood pressure and bradycardia 38 beats per minute due to atrioventricular nodal blockade. Her bradycardia was refractory to atropine and dopamine infusion; but improved with calcium gluconate. She was found to have acute kidney injury and hyperkalemia at 6.4 mEq/L. This is a case of Bradycardia, Renal Failure, Atrioventricular-Nodal Blockers, Shock, and Hyperkalemia (BRASH) syndrome, precipitated by dehydration and perpetuated by atrioventricular blockade, illustrating the degree of bradycardia and electrocardiographic changes being out of proportion to the potassium level. BRASH syndrome should be recognized and intervened early in the course to avoid the patient entering a vicious cycle that could be rapidly fatal.

Evaluation of the causal effects between dopamine infusion changeover and fluctuations in mean arterial pressure in neonates

ObjectiveTo evaluate whether changing dopamine infusions every 12 hours and preparing these infusions 30 min before administration reduces blood pressure fluctuations in preterm and term neonates.DesignThis was a retrospective study using data from live patients on the neonatal unit and prospective study exploring stability of infusions in a laboratory-based neonatal ward simulation.SettingSingle-centre study in a tertiary neonatal surgical unit in a university teaching hospital.PatientsNeonates who received more than one subsequent dopamine infusion and had invasive arterial blood pressure monitoring, during their admission in the neonatal unit, were included.InterventionsAs part of the Quality Improvement project, the standard operating procedure (SOP) was changed, and dopamine infusions were prepared by nursing staff and left to rest for 30 min before administering to the neonate. Additionally, infusions were replaced every 12 hours.Main outcome measuresThe percentage change in mean arterial pressure (MAP) and the percentage loss in the drug concentration during infusion during changeover.ResultsOur findings indicate that up to 15% of the initial dopamine concentration is lost after 24 hours. This results in a sharp variation in the dopamine concentration during infusion changeover that correlates with observed rapid fluctuations in MAP. In changing the SOP, no significant difference in the concentration of dopamine and MAP were observed over 12 hours.ConclusionsDelaying administration of dopamine infusions by 30 min after preparation combined with changing infusions 12 hourly has reduced MAP fluctuations. Therefore, the risks associated with MAP fluctuations, including intraventricular haemorrhages, are reduced.

Renal functional reserve capacity before and after living kidney donation

Compensatory gomerular filtration rate (GFR) increase after kidney donation results in a GFR above 50% of the predonation value. The renal functional reserve (RFR) assessed by the renal response to dopamine infusion (RFRdopa) is considered to reflect functional reserve capacity and is thought to be a tool for living donor screening. However, it is unknown if the RFRdopa predicts long-term kidney function. Between 1984 and 2017, we prospectively measured GFR (125I-iothalamate) and RFR by dopamine infusion in 937 living kidney donors. We performed linear regression analysis of predonation RFRdopa and postdonation GFR. In donors with 5-yr follow-up after donation we assessed the association with long-term GFR. Mean donor age was 52 yr (SD 11); 52% were female. Mean predonation GFR was 114 ml/min (SD 22), GFRdopa was 124 ml/min (SD 24), resulting in an RFR of 9 ml/min (SD 10). Three months postdonation, GFR was 72 ml/min (SD 15) and GFRdopa was 75 ml/min (SD 15), indicating that donors still had RFRdopa [3 ml/min (SD 6), P < 0.001]. Predonation RFRdopa was not associated with predonation GFR [standardized (st.) β −0.009, P = 0.77] but was positively associated with GFR 3 mo after donation (st. β 0.12, P < 0.001). In the subgroup of donors with 5-yr follow-up data ( n = 383), RFRdopa was not associated with GFR at 5 yr postdonation (st. β 0.05, P = 0.35). In conclusion, RFRdopa is a predictor of short-term GFR after living kidney donation but not of long-term kidney function. Therefore, measurement of the RFRdopa is not a useful tool for donor screening. Studies investigating long-term renal adaptation are warranted to study the effects of living kidney donation and improve donor screening.

Effects of intravenous low-dose dopamine infusion on glucose regulation during prolonged aerobic exercise

The carotid body chemoreceptors are activated during hypoglycemia and contribute to glucoregulation during prolonged exercise in dogs. Low-dose intravenous infusions of dopamine have been shown to blunt the activation of the carotid body chemoreceptors during hypoxia. Therefore, we tested the hypotheses that dopamine would blunt glucoregulatory responses and attenuate plasma glucose during prolonged aerobic exercise in healthy participants. Twelve healthy participants completed two randomized exercise sessions at 65% peak oxygen consumption for up to 120 min. Saline was infused during one exercise session, and dopamine (2 μg·kg−1·min−1) was infused during the other session. Arterial plasma glucose, growth hormone, glucagon, cortisol, norepinephrine, and epinephrine were measured every 10 min. Exercise duration during dopamine infusion was 107 ± 6 and 119 ± 0.8 min during saline infusion. Glucose area under the curve during exercise was lower during dopamine (9,821 ± 686 vs. 11,194 ± 395 arbitrary units; P = 0.016). The ratio of circulating growth hormone to glucose and the ratio of glucagon to glucose were greater during dopamine ( P = 0.045 and 0.037, respectively). These results indicate that the infusion of dopamine during aerobic exercise impairs glucoregulation. This suggests that the carotid body chemoreceptors contribute to glucoregulation during prolonged exercise in healthy exercise-trained humans.

Comparison of Dopamine and Norepinephrine in the Treatment of Shock

SOAP II, a multi-center, randomized trial comparing dopamine to norepinephrine in treatment of shock, followed 1679 patients for 12 months. Patients with hypotension persisting despite fluid administration were randomized either to norepinephrine infusion or to dopamine infusion to restore normal blood pressure. The chapter discusses primary and secondary outcomes, including mortality rates in the ICU and hospital at 6 and 12 months. A predefined subgroup analysis was performed according to type of underlying shock (septic, cardiogenic, or hypovolemic). There was no significant difference between the dopamine group and the norepinephrine group in mortality rate or in ICU length of stay or need for organ support. The rate of arrhythmias was significantly higher in the dopamine group (24%) than in the norepinephrine group (12%). Among patients whose shock was cardiogenic in nature, the 28-day mortality was significantly higher in the dopamine group than in the norepinephrine group (p = 0.03).