Allison J. Lee

Cardiac Output Assessed by Invasive and Minimally Invasive Techniques

Cardiac output (CO) measurement has long been considered essential to the assessment and guidance of therapeutic decisions in critically ill patients and for patients undergoing certain high-risk surgeries. Despite controversies, complications and inherent errors in measurement, pulmonary artery catheter (PAC) continuous and intermittent bolus techniques of CO measurement continue to be the gold standard. Newer techniques provide less invasive alternatives; however, currently available monitors are unable to provide central circulation pressures or true mixed venous saturations. Esophageal Doppler and pulse contour monitors can predict fluid responsiveness and have been shown to decrease postoperative morbidity. Many minimally invasive techniques continue to suffer from decreased accuracy and reliability under periods of hemodynamic instability, and so few have reached the level of interchangeability with the PAC.

Ultrasound assessment of the vertebral level of the intercristal line in pregnancy

BACKGROUND: The intercristal line is known to most frequently cross the L4 spinous process or L4-5 interspace; however, it is speculated to be positioned higher during pregnancy because of the exaggerated lumbar lordosis. Clinical estimation of vertebral levels relying on the use of the intercristal line has been shown to often be inaccurate. We hypothesized that the vertebral level of the intercristal line determined by palpation would be higher than the level determined by ultrasound in pregnant women. METHODS: Fifty-one term pregnant patients were recruited. Two experienced anesthesiologists performed estimates of the position of the intercristal line by palpation. Using ultrasound, another anesthesiologist who was blinded to the clinical estimates, determined the position of the superior border of the iliac crest in the transverse and longitudinal planes and then identified the lumbar vertebral levels. The vertebral level at which the clinical estimates of the intercristal line crossed the spine was recorded and compared with the ultrasound-determined level of the superior border of the iliac crest. RESULTS: The clinical estimates of the spinal level of the intercristal line agreed with the ultrasound measurement 14% of the time (14 of 101; 95% confidence interval [CI]: 8%, 22%). The clinical estimates were 1 level higher than the ultrasound measurement 23% of the time (23 of 101; 95% CI: 16%, 32%) and >1 level higher 25% of the time (25 of 101; 1-tailed 95% CI: >18%). The distribution of the clinical estimates found clinicians locating the intercristal line at L3 or L3-4 54% of the time (54 of 101; 95% CI: 44%, 63%) and at L2-3 or higher 27% of the time (27 of 101; 1-tailed 95% CI: >20%). CONCLUSION: The anatomical position of the intercristal line was at L3 or higher in at least 6% of term pregnant patients using ultrasound. Clinical estimates were found to be ≥1 vertebral level higher than the anatomical position determined by ultrasound at least 40% of the time. This disparity may contribute to misidentification of lumbar interspaces and increased risk of neurologic injury during neuraxial anesthesia.

Ultrasound-guided bilateral transversus abdominis plane blocks in conjunction with intrathecal morphine for postcesarean analgesia

STUDY OBJECTIVE To determine whether transversus abdominis plane (TAP) blocks administered in conjunction with intrathecal morphine provided superior analgesia to intrathecal morphine alone. DESIGN Randomized, double-blind, placebo-controlled study. SETTING Operating room of a university hospital. PATIENTS 51 women undergoing elective Cesarean delivery with a combined spinal-epidural technique that included intrathecal morphine. INTERVENTIONS Subjects were randomized to receive a bilateral TAP block with 0.5% ropivacaine or 0.9% saline. Postoperative analgesics were administered on request and selected based on pain severity. MEASUREMENTS Patients were evaluated at 2, 24, and 48 hours after the TAP blocks were performed. Verbal rating scale (VRS) pain scores at rest, with movement, and for colicky pain were recorded, as was analgesic consumption. Patients rated the severity of opioid side effects and their satisfaction with the procedure and analgesia. MAIN RESULTS 51 subjects received TAP blocks with ropivacaine (n = 26) or saline (n = 25). At two hours, the ropivacaine group reported less pain at rest and with movement (0.5 and 1.9 vs 2.8 and 4.9 in the saline group [VRS scale 0 - 10]; P < 0.001) and had no requests for analgesics; there were several requests for analgesia in the saline group. At 24 hours, there was no difference in pain scores or analgesic consumption. At 48 hours, the ropivacaine group received more analgesics for moderate pain (P = 0.04) and the saline group received more analgesics for severe pain (P = 0.01). CONCLUSIONS Transversus abdominis plane blocks in conjunction with intrathecal morphine provided superior early postcesarean analgesia to intrathecal morphine alone. By 24 hours there was no difference in pain scores or analgesic consumption.

Infection associated with central venous or epidural catheters: how to reduce it?

PURPOSE OF REVIEW Central venous catheters are a leading source of nosocomial bloodstream infection with an estimated 10% mortality. Infection associated with epidural catheterization is an uncommon but devastating complication. Diagnosis of spinal epidural abscess requires a high index of suspicion and imaging techniques such as MRI. Early diagnosis and treatment will minimize permanent damage, but primary prevention should be the aim, which depends on proper patient evaluation and use of full aseptic precautions. RECENT FINDINGS Recent studies suggest that epidural infection is no longer as rare a complication as once thought and may be increasing. It is not clear whether this increase is related to an increase in reporting, an overall increase in the total number of epidurals (especially extended use) being performed, or a true increase in infection rate. Implementation of multistep prevention programs has been shown to decrease central venous catheter-related bloodstream infection rate. Antiseptic or antibiotic-impregnated central venous catheters are effective in decreasing central venous catheter-related bloodstream infections. SUMMARY Healthcare worker education and training are essential to create standardization of aseptic care. Continuous surveillance is necessary for identifying lapses in infection-control practices.

Survey of Elective Laryngeal Mask Airway Use in the Presence of Gastroesophageal Reflux Disease

Concern exists about the potential risks of pulmonary aspiration with the laryngeal mask airway (LMA) due to its inability to provide a tight seal at the larynx. The safety of LMA use in the presence of gastroesophageal reflux disease (GERD) is unclear, as GERD is presumed to increase the risk of aspiration under anesthesia. VA Anesthesiolo- gists were surveyed regarding their practices in the setting of mild, moderately severe and severe symptoms of GERD. Approximately half responded that they would use a standard LMA in a patient with GERD as long as symptoms are mild. Nineteen percent would not use the LMA in any patient with a history of GERD.