Biomedical subjects

Stephen M Klein

Publications and source records attributed to Stephen M Klein.

24 records · Page 2Linked to original sources

PubMedDate not supplied

Paravertebral somatic nerve blocks for breast surgery in a patient with hypertrophic obstructive cardiomyopathy.

PURPOSE: Patients with hypertrophic obstructive cardiomyopathy (HOCM), a genetic disorder resulting in idiopathic myocardial thickening, can present the anesthesiologist with significant management difficulties. This report reviews the physiology of this important disease process and describes the use of paravertebral nerve blocks (PVB) in the management of a patient with HOCM who presented for partial mastectomy with axillary lymph node dissection. CLINICAL FEATURES: A 72-yr-old female presented for breast cancer surgery with a significant past medical history of HOCM diagnosed during hospitalization for non-small cell lung cancer. PVB were performed at thoracic levels 1-6 and 5 mL of 0.5% ropivacaine and epinephrine 1:400,000 was injected at each level. Intraoperatively the patient required no other medication for analgesia and was comfortable and conversant during the two-hour procedure. She remained pain free following the operation and did not require any opioid medication until the following day. CONCLUSIONS: PVB provide excellent analgesia and are a useful alternative anesthetic when faced with the HOCM patient requiring major breast surgery.

Aged↗

PubMedDate not supplied

In situ images of the thoracic paravertebral space.

BACKGROUND AND OBJECTIVES: In situ knowledge about the anatomic structures and the path of a needle percutaneously placed into the paravertebral space is an area that continues to be investigated. We describe an endoscopic technique that permits imaging of the contents and boundaries of the thoracic paravertebral space in cadavers. TECHNIQUE: A 43-year-old, 157-cm, 45-kg unembalmed female cadaver was placed in the prone position. Using a 2.3-mm diameter, 0 degree optical angle, fiberoptic ankle arthroscopy scope, trocar, introducer, and light source, thoracic paravertebral blocks were performed. To produce quality images, the trocar was advanced the length of the shaft, approximately 8 cm. The arthroscopy scope was then exchanged with the introducer. The trocar and arthroscopy scope were then gradually withdrawn posterior. RESULTS: Representative images that show the anatomic pathway of a needle as it would be directed into the paravertebral space as well as the boundaries of the thoracic paravertebral space were obtained. These included the costotransverse ligament, the spinal nerve, and the parietal and visceral pleura. CONCLUSIONS: The images help show the relationship of structures that are encountered during a paravertebral block. This new technique may be helpful in examining the spread of local anesthetic using dye or imaging the location of continuous catheters without having to dissect the insertion area.

Adult↗

PubMedDate not supplied

Continuous peripheral nerve block for battlefield anesthesia and evacuation.

Peripheral nerve and continuous peripheral nerve block (CPNB) have the potential to be valuable techniques in combat anesthesia. We describe the first successful application of CPNB in the pain management and surgical management of a combat casualty as he was evacuated from the Iraqi battlefield to the United States.

Adult↗

PubMedDate not supplied

Combined lumbar-plexus and sciatic-nerve blocks: an analysis of plasma ropivacaine concentrations.

BACKGROUND AND OBJECTIVES: Lumbar-plexus and sciatic-nerve blocks are commonly combined for lower-extremity anesthesia using large doses of ropivacaine. Limited information is available about the pharmacokinetics of this practice. We analyzed plasma ropivacaine concentrations after single-injection lumbar-plexus blocks with and without sciatic-nerve blocks. METHODS: Twenty patients having lower-extremity surgery using a lumbar-plexus block with 0.5% ropivacaine with 1:400,000 epinephrine (35 mL, n = 10) or the same lumbar-plexus block with the addition of a sciatic-nerve block (25 mL, n = 10, 60 mL total) using the same solution were enrolled. Venous blood samples were collected at 5, 15, 30, 45, 60, 120, and 240 minutes after block placement and analyzed for total ropivacaine concentration by use of gas chromatography. Individual timepoints, maximum concentrations (C(max)), and time to C(max) (T(max)) were compared. Values are mean +/- SD. RESULTS: Both groups demonstrated a rapid increase in plasma concentration over the first 30 to 45 minutes. Concentrations were greater for those who received both blocks (P = .0005) at all timepoints. The lumbar-plexus block C(max) was less (986 +/- 221 ng/mL) than for the combined blocks (1,560 +/- 351 ng/mL, P = .0004). The T(max) was greater for the lumbar plexus (80 +/- 49 min) than for the combined blocks (38 +/- 22 min, P = .03). There was no relationship between the C(max) and patient age, weight, or body mass index. CONCLUSIONS: The results of this study demonstrate that the plasma ropivacaine concentrations increase quicker when a sciatic-nerve block is added to a lumbar-plexus block, but C(max) remains below the toxicity threshold.

Adult↗

PubMedDate not supplied

Altered perceptions after upper and lower extremity blocks: an initial investigation.

BACKGROUND AND OBJECTIVES: Nerve blocks frequently produce unusual altered perceptions in the extremities. We examined perceptual changes experienced after peripheral blocks. METHODS: Fifty consecutive patients having an upper or lower extremity block for surgery participated in this prospective study. Patients were divided into 2 groups: upper extremity (n = 20) and lower extremity (n = 30). Each group was asked a list of questions about perceptions of limb sensation, length, weight, and location and given a detailed 2-point discrimination test over the V(1)-V(3) divisions of the trigeminal nerve prior to block and sedation. While the extremity was still blocked, the exam was repeated before postanesthesia care unit discharge. RESULTS: In both groups, 98% of patients described altered limb perception. The perceptions in the upper extremity were: heaviness, 60%; numbness, 50%; warmth, 40%; pain, 30%; full or fat, 20%; floating, 5%; shorter, 0%; or thinner, 10%. The perceptions in the lower extremity were: numbness, 75%; heaviness, 46%; warmth, 33%; pain, 32%; full or fat, 36%; floating, 25%; shorter, 18%, or thinner, 7%. Upper extremity block patients were more likely to describe the limb as lighter (P <.0001); the lower extremity group was more likely to describe the limb as numb (P =.01) or floating (P =.0002). There was no difference in the ability to correctly identify the location of the limb between the groups. There was no difference in 2-point discrimination between each assessment for either group. CONCLUSION: The results of this study confirm and quantify the perceptions experienced by patients undergoing upper and lower extremity blocks. These perceptions are prevalent. This knowledge is helpful in providing patients with accurate preoperative preparation. Further investigation is warranted to determine the neurologic etiology of these observations.

Adult↗

PubMedDate not supplied

Paravertebral somatic nerve block compared with peripheral nerve blocks for outpatient inguinal herniorrhaphy.

BACKGROUND: Inguinal herniorrhaphy (IH) is a common outpatient procedure, yet postoperative pain and anesthetic side effects remain a problem. Paravertebral somatic nerve blocks (PVB) have the potential to offer unilateral abdominal wall anesthesia and long-lasting pain relief with minimal side effects. We compared PVB with peripheral neural blocks for outpatient IH. METHODS: Forty-six patients scheduled for IH were entered into this prospective, single-blind study. All patients underwent a standardized general anesthetic. Patients were randomly assigned to receive a PVB (levels T10-L2) preoperatively (n = 24) or an intraoperative peripheral block (PB) by the surgeon (n = 22), using 0.5% ropivacaine (40 mL). Opioid use, verbal analog pain scores, and side effects were documented for 72 hours. RESULTS: The use of opioids during surgery was less for the PVB group 162 +/- 70 mg than the PB group, 210 +/- 60 (P =.02). Need for opioids in PACU was less for the PVB group (39%) than the PB group (61%) (P =.002). Time until first pain after discharge was not different between groups, 312 +/- 446 minutes (PB) and 425 +/- 384 minutes (PVB) (P =.12). Of the PVB patients, 29% used no opioids at all compared with 18% of PB patients (P =.12). Mean time until first oxycodone use was similar between groups, 303 +/- 469 minutes (PB) and 295 +/- 225 minutes (PVB) (P =.18). Oxycodone use was also similar; 35 +/- 34 mg (PVB) versus 49 +/- 42 mg (PB) (P =.30). More patients in the PB group (50%) required antiemetic treatment in the postanesthesia care unit than the PVB group (21%) (P <.001). Side effects were similar at all other measurements. CONCLUSIONS: This study shows that PVB provides analgesia equivalent to extensive peripheral nerve block for inguinal herniorrhaphy, offering an alternative method of postoperative pain management and perhaps fewer side effects.

Abdominal Wall↗