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Biomedical subjects

K G Knape

Publications and source records attributed to K G Knape.

11 recordsLinked to original sources
PubMed1997

A comparison of catheter vs needle injection of local anesthetic for induction of epidural anesthesia for cesarean section.

It is generally believed that bolus injections of local anesthetic through an epidural needle produce a more rapid onset of blockade, but at the expense of an increased incidence and severity of hypotension, whereas intermittent injections through a catheter take longer to achieve adequate anesthesia but with a lower risk of hypotension. The present study investigated two commonly used needle and catheter epidural injection techniques for differences in speed of onset of surgical anesthesia and incidence and severity of hypotension. Term parturients scheduled for elective cesarean section were randomized into two groups to receive epidural anesthesia with intermittent injection either through the epidural needle (n = 44) or via a previously placed catheter (n = 44). The incidence and severity of hypotension was similar in the two groups. No significant difference was found for the time to onset of surgical anesthesia. In the absence of benefits of needle injection, incremental catheter administration of local anesthetic with its multiple safety advantages is the technique of choice for induction of epidural anesthesia for cesarean section.

Clinical Trial↗
PubMed1996

No additional metal particle formation using the needle-through-needle combined epidural/spinal technique.

BACKGROUND: Combined epidural/spinal analgesia utilizing a needle-through-needle technique has become very popular in anesthesia. However, findings of concave deformities at the orifice of Tuohy needles after spinal needle passage have raised concerns that metal fragments might be deposited within the epidural space. This study was proposed to investigate whether the needle-through-needle technique does produce metallic flecks. METHODS: Ten unused Tuohy and Hustead epidural needles were inspected microscopically and photomicrographed prior to flushing saline through each into a single tissue culture well. After drying, a single pass was made with a 120 mm 24-gauge Sprotte needle through each epidural needle to maximal extension while the orifice was within another tissue culture well. Each needle was again flushed into a third well before reexamination and photomicroscopy. Each of the wells was inspected for metallic particles by microscopy. Additional freshly unpackaged Tuohy needles were microscopically examined after exposure to a magnetic field. RESULTS: Comparison of micrographs before and after needle experiments revealed concave deformities at the orifice of all the Tuohy and Hustead needles. No particles were observed in either of the two saline-flushed wells or within the well in which the needle-through-needle passes were made. Inspection of unused Tuohy needles exposed to a magnetic field revealed metal filings "standing up" along the bevel of every needle examined. CONCLUSIONS: Metallic particles are not produced by the needle-through-needle technique. However, metal particles are an apparent contaminant of all epidural needles and are probably routinely introduced into patients when the needle is placed.

Analgesia, Epidural↗
PubMed1995

Epidural analgesia and uterine function.

OBJECTIVE: To determine whether continuous epidural analgesia with bupivacaine and fentanyl affects the rate of cervical dilation and myometrial contractility. METHODS: In a 5-week period, 62 consecutive women who received standardized epidural analgesia were matched with the next two groups of 124 consecutive women of the same parity who did not receive epidural analgesia. The outcome variables were uterine activity, rate of cervical dilation, oxytocin therapy, and operative deliveries. RESULTS: Continuous epidural analgesia with bupivacaine and fentanyl did not result in a change in myometrial contractility in the first hour after the initiation of analgesia. However, despite more oxytocin therapy, the rate of cervical dilation was significantly lower in the epidural group than in the nonepidural group (1.9 versus 5.6 cm/hour, P < .001). Operative deliveries were more common in patients with epidural analgesia than in those without it (12 of 62 versus two of 124, P < .001). CONCLUSION: After epidural analgesia, myometrial contractility is maintained with oxytocin, but the ability of the uterus to dilate the cervix is reduced significantly.

Analgesia, Epidural↗
PubMed1989

Incidence of venous air embolism during cesarean section is unchanged by the use of a 5 to 10 degree head-up tilt.

One hundred healthy parturients were divided at random into two demographically similar groups and were positioned for cesarean section either horizontally or flexed 5 to 10 degrees head up, with a 15 degrees lateral tilt. A Doppler ultrasound transducer was positioned over the fourth intercostal space parasternally. Initially, two patients received spinal, three general, and 95 epidural anesthesia. Two patients subsequently needed general for failed epidural anesthesia. Changes in Doppler heart tones (greater than 15 sec duration) indicative of venous air embolism (VAE) were identified 15 times in 11 patients--seven in supine and four in head-up patients (no statistically significant difference). Six awake patients (three horizontal, three head-up) developed chest tightness or pain during surgery, but only one episode correlated with VAE. No patient developed breathlessness. Moderate hypotension (greater than 10% decrease in systolic arterial pressure [SAP]) occurred in seven of 11 (63.6%) patients with, and in 26 (29.2%) of 89 patients without, VAE (P less than 0.001). More severe hypotension (SAP less than 90 mm Hg) due to bleeding occurred once. We conclude that a modest (5-10 degrees) head-up position does not influence the occurrence of VAE in patients having cesarean section. An 11% incidence of clinically insignificant VAE, although low, is still worrisome, as even small air bubbles in the circulation are potentially harmful, especially if the foramen ovale is patent. VAE during cesarean section should be anticipated and the anesthetic management planned accordingly.

Adult↗
PubMedDate not supplied

Lidocaine hydrocarbonate is not superior to lidocaine hydrochloride in interscalene brachial plexus block.

To determine the effect of carbonation of lidocaine, a comparison of 1.0% lidocaine hydrochloride (HCl) and 1.1% lidocaine hydrocarbonate (CO2), both with 1:200,000 epinephrine, was made in this study of 50 patients receiving interscalene brachial plexus blocks. Sensory block was determined by the response to pinprick in the C2-T2 dermatomes, while motor block was assessed by the development of paresis and paralysis at the shoulder and hand. The percentage of patients developing analgesia (decreased sensation to pinprick) and anesthesia (total absence of sensation to pinprick) at each dermatome level as well as the percentage of patients developing motor block was not significantly different between the two forms of lidocaine. The initial onset of analgesia [lidocaine HCl, 4.0 +/- 2.4 (SD) minutes; lidocaine CO2, 4.3 +/- 3.8 (SD) minutes] and anesthesia [lidocaine HCl, 10.1 +/- 5.7 (SD) minutes; lidocaine CO2, 7.8 +/- 4.4 (SD) minutes] did not differ significantly between the two groups. At the individual dermatomes, there was no difference in the onset of analgesia except at one dermatome level, C7, which was near the level of local anesthetic injection. Anesthesia onset in each dermatome as well as the onset of motor block did not differ between the two groups. It is concluded that lidocaine CO2 does not offer any significant clinical advantage over lidocaine HCl in interscalene brachial plexus block.

Adult↗