Search

The transmuscular quadratus lumborum (TQL) block is one of the recently evolved myofascial blocks utilised in abdominal surgery. It involves injecting local anaesthetic into the fascial plane anterior to the thoracolumbar fascia. This block has previously been described with a transverse oblique paramedian approach at the L2 level in the sitting position. We describe a TQL block at the same level in the lateral position using a transverse posterolateral approach to provide analgesia for patients undergoing abdominal surgery. We elaborate on these two approaches of TQL block at the L2 level, in relation to the anatomy, sonoanatomy and technical aspects.

The timing and magnitude of drug onset can be influenced by factors in the chain of drug delivery from the site of administration to the site of effect. This review examines recent evidence regarding the contribution and significance of these factors.

The myocardial kinetics and dynamics of thiopental (750mg over 2 min) were examined in chronically instrumented sheep (five studies in four sheep). The myocardial kinetics were studied by simultaneous rapid sampling of arterial and coronary sinus blood for 30min. The myocardial kinetics for four of the five studies were best described by a single flow-limited compartment with apparent volumes of between 42 and 113mL. These volumes equated to half-lives of equilibration between blood and myocardium of between 0.49 and 1.00min when baseline blood flow was taken into account. The remaining study was better described by a model with a slight membrane limitation (permeability/flow ratio of approximately 2). Myocardial contractility was studied as a measure of myocardial pharmacodynamics and was reduced to 53% of baseline at approximately 2.5min after the start of the dose. Effect compartment analysis showed that there was hysteresis between the time course of these contractility changes and the time course of the arterial concentrations, with effect compartment half-lives between 0.08 and 0.87min. There was significantly less hysteresis for the coronary sinus concentrations. It is concluded that thiopental equilibrated rapidly with a component of the myocardium, and that consequently its effects on myocardial contractility also rapidly equilibrated with both afferent and effluent myocardial blood.