ABSTRACT
To provide further evidence for the lipid sink theory, we have developed an in vitro model to assess the effect of Intralipid® 20% on methaemoglobin formation by drugs of varying lipid solubility. Progressively increasing Intralipid concentrations from 4 to 24 mg.ml⻹ suppressed methaemoglobin formation by the lipid soluble drug glyceryl trinitrate in a dose-dependent manner (p < 0.001). Both dose and timing of administration of Intralipid to blood previously incubated with glyceryl trinitrate for 10 and 40 min resulted in significant suppression of methaemoglobin formation (p < 0.0001 and p < 0.05, respectively). Mathematical modelling demonstrated that the entire process of methaemoglobin formation by glyceryl trinitrate was slowed down in the presence of Intralipid. Intralipid did not significantly suppress methaemoglobin formation induced by 2-amino-5-hydroxytoluene (partially lipid soluble) or sodium nitrite (lipid insoluble; both p > 0.5). This work may assist determination of the suitability of drugs taken in overdose for which Intralipid might be deployed.
Subject(s)
Blood/drug effects , Fat Emulsions, Intravenous/pharmacology , Lipids/blood , Methemoglobin/antagonists & inhibitors , Algorithms , Blood Gas Analysis , Dose-Response Relationship, Drug , Humans , Lipids/chemistry , Methemoglobin/biosynthesis , Models, Statistical , Nitroglycerin/antagonists & inhibitors , Nitroglycerin/chemistry , Nitroglycerin/pharmacology , Sodium Nitrite/antagonists & inhibitors , Sodium Nitrite/chemistry , Sodium Nitrite/pharmacology , Solubility , Vasodilator Agents/antagonists & inhibitors , Vasodilator Agents/chemistry , Vasodilator Agents/pharmacologyABSTRACT
A 38-year-old woman experienced a massive postpartum haemorrhage 30 minutes after emergency caesarean delivery. The patient became severely haemodynamically compromised with an unrecordable blood pressure. Rapid fluid resuscitation was limited by the capacity of the intravenous cannula in place at the time and inability to establish additional vascular access using conventional routes in a timely manner. An intraosseous needle was inserted in the proximal humerus at the first attempt and administration of resuscitation fluid by this route subsequently enabled successful placement of further intravenous lines. Blood and blood products were deployed in conjunction with intra-operative cell salvage and transoesophageal Doppler cardiac output monitoring was used to assess adequacy of volume replacement. Haemorrhage control was finally achieved with the use of recombinant factor VIIa and hysterectomy.