Practice pearls for common emergencies (Proceedings)

ADVERTISEMENT

Practice pearls for common emergencies (Proceedings)

May 01, 2011

Vascular access

Successful, efficient, sterile placement ofintravenous (IV) catheters should be mastered by all providing care of the emergent patient. It should be understood that placement of short, large-bore peripheral catheters provide the most rapid means for intravascular volume expansion. However, venous cannulation may prove difficult in the hypovolemic, shocky patient. It must be remembered that hypovolemia decreases the pressure gradient between the arterial and venous systems, making aggressive manual venous occlusion a risk for impairing arterial flow to the limb and being counterproductive in providing venous engorgement. In this situation, a facilitating incision or mini-cutdown may prove helpful to properly visualize the vessel.

Placement of a peripherally inserted central catheter (PICC line) may be preferred in patients that require the administration of substances with increased osmolality (diazepam infusions, parenteral nutrition, dextrose supplemented fluids, etc), patients that require frequent blood sampling or those prone to severe bruising (thrombocytopenia). Standard through-the-needle catheters are prone to mechanical occlusion (kinking). Replacing the needle with a similar sized peripheral catheter offers an option that has proven to lower the risk for kinking. These catheters may be successfully placed in most common peripheral vascular sites, however, venous valves may provide added obstacles with full advancement of the central catheter.

Catheter-related bloodstream infections (CR-BSI) are a preventable cause of morbidity and mortality. Interventions that enhance provider awareness of CR-BSI, consolidate catheter equipment and supplies into a catheter cart or tote, confirm the continued need of catheters on a daily basis, and empower nurses to enforce adherence to evidence-based infection control practices have been shown to nearly eliminate CR-BSI in human intensive care units.

Packed cell volume and total solids

Whole blood components include red blood cells (RBCs), white blood cells (WBCs) platelets and plasma. Centrifugation of hematocrit tubes separates blood into plasma, packed RBC and a buffy coat (BC) layer. These parameters should be routinely evaluated in emergency patients that are having bloodwork performed and/or being started on intravenous fluid therapy. This information may provide rapid insight as to overall hydration status, total RBC mass, total protein levels (including albumin), condition of serum (lipemia, hemolysis, icterus, etc), and function as a weak indicator of elevated WBC or platelet numbers in the patient.

Acute hemorrhage causes a variety of alterations in the PCV/TS depending on the time from the initial insult. Beginning immediately after blood loss and continuing for 48-72 hours after blood loss, interstitial fluid moves into the vessels to replace the lost volume, decreasing PCV/TS values over time. Also in response to acute hemorrhage, the spleen contracts, releasing RBCs, but not protein. If the PCV/TS are measured soon after the onset of hemorrhage, the PCV will be normal or elevated, with a normal TS. As time progresses or when IV fluids are administered, the PCV and TS will decrease as the intravascular volume is replaced. With acute alterations, the PCV/TS should be measured frequently (ie. as often as every 30-60 minutes) to monitor for conditions requiring blood component therapy.

Alterations in hydration status will also alter the PCV/TS. They will increase or decrease simultaneously depending on whether water, not blood, is gained (over hydration) or lost (dehydration or hemoconcentration). Using the PCV/TS to assess hydration status often reveals a more severe dehydration than is assessed by mucous membrane moisture and skin turgor.

If only the PCV is low with normal TS, etiologies may include RBC destruction, decreased RBC production, or chronic cavitary hemorrhage. If the PCV is low to normal, with high TS, there may be an elevated globulin level or concomitant dehydration. If only the PCV is elevated along with a normal TS, look for conditions that cause dehydration or hemoconcentration masked by hypoproteinemia (hemorrhagic gastroenteritis) or an absolute increase in RBCs (polycythemia / erythrocytosis). If the PCV is elevated with low TS, suspect splenic contraction with pre-existing hypoproteinemia.

Anesthesia

The provision of anesthesia is necessary for successful treatment of many emergency disorders. Although risks inherent to this patient population cannot be completely eliminated, care can be taken to limit this risk in a patient population that is more vulnerable to its associated complications (hypothermia, hypotension, hypoventilation, cardiopulmonary arrest, etc) through the proper administration of premedications and IV fluid support, in addition to proper utilization of anesthetic monitoring.

It is with rare exception, that anesthesia should be provided in the absence of systemic analgesics (primarily opioids, less frequently lidocaine or NSAIDs, rarely alpha2-agonists) ± sedatives (primarily benzodiazepines, rarely phenothiazine derivatives). Clinical conditions that may justify the administration of anesthesia without a premedication are those disorders where a rapid and full recovery from anesthesia is best for the patient. This becomes an invalid argument if the patient underwent a procedure that evokes a sustained painful stimulus upon awakening.

In addition to administering appropriate premedications and IV fluid support, anesthetic monitoring is imperative for a safe anesthetic period for the patient. There is no argument that multi-parameter monitoring is advocated for all anesthetic events lasting longer than the time it takes to instrument the patient. Although a pulse oximeter is probably the single most commonly used anesthetic monitoring modality, it provides the least amount of clinically useful information in a patient receiving 100% oxygen. Instead, both blood pressure monitoring and end-tidal carbon dioxide monitoring provide more clinically useful information, based on the rate of anesthetic complications that involve one of these parameters.