Local infiltration anesthesia with high dose ropivacaine and dexmedetomidine in major knee surgery is safe.

Background: The role of local infiltration anesthesia (LIA) in knee surgery is significant. LIA can be more potent than a nerve block, but without the downsides. A wide range of agents are used for LIA, including some off-label medications such as dexmedetomidine and ropivacaine.

Pharmacodynamics and Pharmacokinetics of Lidocaine in a Rodent Model of Diabetic Neuropathy.

Background: Clinical and experimental data show that peripheral nerve blocks last longer in the presence of diabetic neuropathy. This may occur because diabetic nerve fibers are more sensitive to local anesthetics or because the local anesthetic concentration decreases more slowly in the diabetic nerve. The aim of this study was to investigate both hypotheses in a rodent model of neuropathy secondary to type 2 diabetes.

Minimum local anesthetic volumes for a selective saphenous nerve block: a dose-finding study.

Background: Saphenous nerve block contributes to analgesia after knee and lower leg surgery. However, literature reports a wide range of volumes of local anesthetic being used for this block.

Methods: A non-randomized controlled trial in a single university hospital in March 2015.

Clamshell thoracotomy and open heart massage--A potential life-saving procedure can be taught to emergency physicians: An educational cadaveric pilot study.

Aims: Selected patients in traumatic cardiac arrest may benefit from pre-hospital thoracotomy. Pre-hospital care physicians rarely have surgical training and the procedure is rarely performed in most European systems. Limited data exists to inform teaching and training for this procedure.

Failure of action potential propagation in sensory neurons: mechanisms and loss of afferent filtering in C-type units after painful nerve injury.

The T-junction of sensory neurons in the dorsal root ganglion (DRG) is a potential impediment to action potential (AP) propagation towards the CNS. Using intracellular recordings from rat DRG neuronal somata during stimulation of the dorsal root, we determined that the maximal rate at which all of 20 APs in a train could successfully transit the T-junction (following frequency) was lowest in C-type units, followed by A-type units with inflected descending limbs of the AP, and highest in A-type units without inflections. In C-type units, following frequency was slower than the rate at which AP trains could be produced in either dorsal root axonal segments or in the soma alone, indicating that the T-junction is a site that acts as a low-pass filter for AP propagation.

Arterial line in prehospital emergency settings - A feasibility study in four physician-staffed emergency medical systems.

Background And Aim Of The Study: Arterial lines are widely used in operating rooms, critical care and emergency departments. Although invasive arterial blood pressure monitoring and arterial blood gas analysis are prehospitally available, the use of arterial lines in the field remains an exception. This study evaluates the feasibility, indications and therapeutic consequences of prehospital arterial line insertion.

Pain tests provoke modality-specific cardiovascular responses in awake, unrestrained rats.

Nociception modulates heart rate (HR) and mean arterial pressure (MAP), suggesting their use of HR and MAP as indicators of pain in animals. We explored this with telemetric recording in unrestrained control and neuropathic (spinal nerve ligation) rats. Plantar stimulation was performed emulating techniques commonly used to measure pain, specifically brush stroke, von Frey fiber application, noxious pin stimulation, acetone for cooling, and radiant heating, while recording MAP, HR, and specific evoked somatomotor behaviors (none; simple withdrawal; or sustained lifting, shaking, and grooming representing hyperalgesia).

Calcium signaling in intact dorsal root ganglia: new observations and the effect of injury.

Background: Ca is the dominant second messenger in primary sensory neurons. In addition, disrupted Ca signaling is a prominent feature in pain models involving peripheral nerve injury. Standard cytoplasmic Ca recording techniques use high K or field stimulation and dissociated neurons.

Prehospital lung ultrasound in the distinction between pulmonary edema and exacerbation of chronic obstructive pulmonary disease.

We present 2 cases of dyspneic patients, where prehospital lung ultrasound helped to distinguish between pulmonary edema and acute exacerbation of chronic obstructive pulmonary disease.

Baroreceptor reflex is suppressed in rats that develop hyperalgesia behavior after nerve injury.

The baroreceptor reflex buffers autonomic changes by decreasing sympathetic activity and increasing vagal activity in response to blood pressure elevations, and by the reverse actions when the blood pressure falls. Because of the many bidirectional interactions of pain and autonomic function, we investigated the effect of painful nerve injury by spinal nerve ligation (SNL) on heart rate (HR), blood pressure (BP) and their regulation by the baroreceptor reflex. Rats receiving SNL were separated into either a hyperalgesic group that developed sustained lifting, shaking and grooming of the foot after plantar punctate nociceptive stimulation by pin touch or a group of animals that failed to show this hyperalgesic behavior after SNL.

Axotomy depletes intracellular calcium stores in primary sensory neurons.

Background: The cellular mechanisms of neuropathic pain are inadequately understood. Previous investigations have revealed disrupted Ca signaling in primary sensory neurons after injury. The authors examined the effect of injury on intracellular Ca stores of the endoplasmic reticulum, which critically regulate the Ca signal and neuronal function.

Depletion of calcium stores in injured sensory neurons: anatomic and functional correlates.

Background: Painful nerve injury leads to disrupted Ca signaling in primary sensory neurons, including decreased endoplasmic reticulum (ER) Ca storage. This study examines potential causes and functional consequences of Ca store limitation after injury.

Methods: Neurons were dissociated from axotomized fifth lumbar (L5) and the adjacent L4 dorsal root ganglia after L5 spinal nerve ligation that produced hyperalgesia, and they were compared to neurons from control animals.

Guidance of block needle insertion by electrical nerve stimulation: a pilot study of the resulting distribution of injected solution in dogs.

Background: Little is known regarding the final needle tip location when various intensities of nerve stimulation are used to guide block needle insertion. Therefore, in control and hyperglycemic dogs, the authors examined whether lower-intensity stimulation results in injection closer to the sciatic nerve than higher-threshold stimulation.

Methods: During anesthesia, the sciatic nerve was approached with an insulated nerve block needle emitting either 1 mA (high-current group, n = 9) or 0.

Restoration of calcium influx corrects membrane hyperexcitability in injured rat dorsal root ganglion neurons.

Background: We have previously shown that a decrease of inward Ca(2+) flux (I(Ca)) across the sensory neuron plasmalemma, such as happens after axotomy, increases neuronal excitability. From this, we predicted that increasing I(Ca) in injured neurons should correct their hyperexcitability.

Methods: The influence of increased or decreased I(Ca) upon membrane biophysical variables and excitability was determined during recording from A-type neurons in nondissociated dorsal root ganglia after spinal nerve ligation using an intracellular recording technique.

Modulators of calcium influx regulate membrane excitability in rat dorsal root ganglion neurons.

Background: Chronic neuropathic pain resulting from neuronal damage remains difficult to treat, in part, because of incomplete understanding of underlying cellular mechanisms. We have previously shown that inward Ca2+ flux (I(Ca)) across the sensory neuron plasmalemma is decreased in a rodent model of chronic neuropathic pain, but the direct consequence of this loss of I(Ca) on function of the sensory neuron has not been defined. We therefore examined the extent to which altered membrane properties after nerve injury, especially increased excitability that may contribute to chronic pain, are attributable to diminished Ca2+ entry.

Species and strain differences in rodent sciatic nerve anatomy: implications for studies of neuropathic pain.

Hindlimb pain models developed in rats have been transposed to mice, but assumed sciatic nerve neuroanatomic similarities have not been examined. We compared sciatic nerve structural organization in mouse strains (C57BL/6J, DBA/2J, and B6129PF2/J) and rat strains (Wistar, Brown Norway, and Sprague-Dawley). Dissection and retrograde labeling showed mouse sciatic nerve origins predominantly from the third lumbar (L3) and L4 spinal nerves, unlike the L4 and L5 in rats.

Contribution of calcium channel subtypes to the intracellular calcium signal in sensory neurons: the effect of injury.

Background: Although the activation-induced intracellular Ca signal is disrupted by sensory neuron injury, the contribution of specific Ca channel subtypes is unknown.

Methods: Transients in dissociated rat dorsal root ganglion neurons were recorded using fura-2 microfluorometry. Neurons from control rats and from neuropathic animals after spinal nerve ligation were activated either by elevated bath K or by field stimulation.

Painful nerve injury shortens the intracellular Ca2+ signal in axotomized sensory neurons of rats.

Background: Neuropathic pain is inadequately treated and poorly understood at the cellular level. Because intracellular Ca signaling critically regulates diverse neuronal functions, the authors examined effects of peripheral nerve injury on the Ca transient that follows neuronal activation.

Methods: Cytoplasmic Ca levels were recorded by digital microfluorometry from dissociated dorsal root ganglion neurons of hyperalgesic animals after ligation of the fifth lumbar spinal nerve and control animals.

Opposing effects of spinal nerve ligation on calcium-activated potassium currents in axotomized and adjacent mammalian primary afferent neurons.

Unlabelled: Calcium-activated potassium channels regulate AHP and excitability in neurons. Since we have previously shown that axotomy decreases I(Ca) in DRG neurons, we investigated the association between I(Ca) and K((Ca)) currents in control medium-sized (30-39 microM) neurons, as well as axotomized L5 or adjacent L4 DRG neurons from hyperalgesic rats following L5 SNL. Currents in response to AP waveform voltage commands were recorded first in Tyrode's solution and sequentially after: 1) blocking Na(+) current with NMDG and TTX; 2) addition of K((Ca)) blockers with a combination of apamin 1 microM, iberiotoxin 200 nM, and clotrimazole 500 nM; 3) blocking remaining K(+) current with the addition of 4-AP, TEA-Cl, and glibenclamide; and 4) blocking I(Ca) with cadmium.