Intradermal ketorolac for reduction of epidural back pain.

Between 30 and 45% of all parturients receiving epidural laboring analgesia complain of postpartum back pain. Although long-term or chronic back pain has been reported, our study focuses on acute or short-term back pain that resolves within 72 h. The purpose of this randomized double-blind, placebo-controlled investigation was to determine if a ketorolac/lidocaine intradermal anesthesia combination could decrease post-epidural back pain. A total of 81 non-complicated parturients requesting epidural analgesia were approached for inclusion and randomized to receive either 3 mL of 1% lidocaine (control group) or 3 mL of 1% lidocaine with 6 mg ketorolac (experimental group) for dermal anesthesia. A 0-10 verbal numeric scale was used to assess pain at rest and with activity at 24 and 72 h. Demographics, mode of delivery, and duration of labor were noted. A chi2 test was used to analyse frequency data and a Student's t-test and generalized estimation equation were used to analyze ordinal and interval data. Demographics, mode of delivery and length of labor were similar between groups. Significantly lower verbal numeric scores were noted in the experimental group at the 24-h active measurements after vaginal delivery and at 24 and 72 h for both active and resting measurements after cesarean delivery. Based on these findings it can be recommended that intradermal ketorolac given at the time of epidural catheter placement may result in a reduction in post-epidural back pain in the parturient, especially in the event of cesarean delivery.

The addition of interscalene block to general anesthesia for patients undergoing open shoulder procedures.

Several studies have demonstrated that interscalene brachial plexus anesthesia alone decreases postoperative pain, nausea, vomiting, urinary retention, and unplanned hospital admissions compared with general anesthesia alone. Anecdotal evidence suggests that an interscalene block combined with general anesthesia decreases unwanted effects of general anesthesia following open shoulder surgery. We compared the effect of combined interscalene block and general anesthesia with general anesthesia alone on Aldrete scores, length of postanesthesia care unit (PACU) stay, verbal rating scale (VRS) pain scores, incidence of postoperative narcotic administration and nausea, and patient satisfaction in a convenience sample of 52 men and women, ASA physical status I, II, or III. Group 1 received standard general anesthesia alone. Group 2 received an interscalene block in combination with general anesthesia using a standard technique. Group 2 had significantly lower VRS scores than group 1 while in the PACU, on the day of surgery, and on postoperative days 1 and 2. Overall satisfaction with the anesthetic technique was higher in the group 2 than in group 1. Results suggest that adding an interscalene block to general anesthesia can be of value in today's outpatient-dominated surgery schedule.

The effect of arthroscopic irrigation fluid warming on body temperature.

The use of room temperature solutions for body cavity irrigation during surgical procedures can lead to the development of perioperative hypothermia. Hypothermia during this period causes patient discomfort, increases oxygen consumption, interferes with the clotting cascade, and increases the length of hospital stay. Perioperative hypothermia in anesthetized patients also contributes to extended sedation, delayed emergence, and prolonged recovery from neuromuscular blockade. Twenty-four adult American Society of Anesthesiologists (ASA) class I and II patients were randomly assigned to receive warmed arthroscopic irrigation solution or room-temperature irrigation solution in this randomized, prospective study. Tympanic temperatures were monitored every 15 minutes throughout the surgical and postanesthesia recovery periods. P < .05 was considered significant. Statistical comparison of the mean percent temperature decrease from preoperative baseline between the 2 groups did not support the hypothesis that patients receiving warmed irrigation solution would maintain a higher core body temperature than those receiving room temperature solution.

Quantification of insensible water loss associated with insufflation of nonhumidified CO2 in patients undergoing laparoscopic surgery.

A growing number of surgical procedures of increased duration are being performed using laparoscopic techniques. No study to date has quantitated the potential insensible water loss associated with laparoscopic surgical procedures as a result of intra-abdominal humidification of insufflated nonhumidified CO2 gas. The purpose of this study was to quantitate this insensible water loss by measuring the CO2 gas volume consumed and the relative humidity of the vented gas. Ten patients presenting for elective procedures were enrolled in this descriptive prospective IRB-approved study. After secondary trocar placement and attainment of the desired intra-abdominal pressure, vented laparoscopic gas was passed directly through a dewpoint monitor sensor. Determinations of dewpoint and gas temperature were made immediately after the start of the surgical procedure and every 15 minutes thereafter until completion. Dew-point temperature was converted to relative humidity, which was used to determine the water vapor content of the gas. The actual water content (absolute humidity) of the vented laparoscopic gas was then calculated from the water vapor volume. The mean relative humidity of the vented laparoscopic gas was 92.2% +/- 0.8%. The mean laparoscopic gas flow rate was 42.0 +/- 5.0 L/h. The mean volume of water (absolute humidity) loss attributed to humidification of dry CO2 was found to be less than 1 mL/h. Insufflation of dry CO2 during laparoscopic procedures therefore results in insignificant insensible water loss.

Effect of intrathecal fentanyl dose on the duration of labor analgesia.

The short duration of effective analgesia produced by intrathecal fentanyl (ITF) at doses ranging from 5 to 25 micrograms limits the drug's use for the management of labor pain. The understanding of the potential of ITF related to duration of analgesia in the labor patient is derived from studies of and clinical experience with ITF at doses not exceeding 25 micrograms and less. We hypothesized that by increasing the dose beyond 25 micrograms, a prolonged duration of analgesia could be achieved. The purpose of the present study was to compare the difference in duration of effective analgesia and adverse effects produced by 25, 37.5, and 50 micrograms of ITF. A sample population of 60 term parturient women with uncomplicated singleton pregnancies who were in active labor and requesting pain control were randomly assigned to 1 of 3 groups: group 1, 25 micrograms (n = 20); group 2, 37.5 micrograms (n = 20); and group 3, 50 micrograms (n = 20). The ITF was then administered by an anesthesia provider blinded to the dose via a combined spinal epidural technique. The time from injection to the time of request for subsequent pain control (considered the duration of effective analgesia), maternal and fetal vital signs, and adverse effects were recorded at specific intervals until the patient requested activation of the epidural catheter or delivery occurred, ending participation in the study. Statistical analysis using a 1-way analysis of variance and considering a P value of < .05 to be significant revealed no difference in duration of effective analgesia between the groups. Statistical differences in the incidence of adverse effects, particularly uterine hyperstimulation, hypotension, pruritus, nausea, and fetal heart rate decelerations were not evident using the Fisher Irwin test and a significance of P < .05. The findings of the present study demonstrate that there is no real advantage of using doses of ITF greater than 25 micrograms in quality and duration of effective labor analgesia.

8-ISO-PGF2alpha production by alveolar macrophages exposed to hyperoxia.

Oxygen exposure for a sufficient duration at high partial pressure results in pulmonary edema in humans and animals. Although the specific mediators of oxygen toxicity are unknown, evidence suggests that oxygen-based radicals such as superoxide anion (O2.) are increased in the lungs in the presence of hyperoxia and contribute to this injury. A series of isomeric prostanoid compounds, the isoprostanes, are formed by the free radical-initiated lipid peroxidation of arachidonic acid (AA). One of these isomers, 8-iso-PGF2alpha, is elevated in the bronchial alveolar lavage fluid of rats exposed to 90% oxygen for 48 h and is associated with a significant increase in protein accumulation in the pulmonary extravascular space. Alveolar macrophages (AMs) are capable of producing large quantities of (O2.), suggesting a role in pulmonary oxygen toxicity. We hypothesized that isolated rat AMs exposed to hyperoxia generate increased amount of 8-iso-PGF2alpha. AMs were exposed to air or 90% oxygen for 6, 12, 24, 48, 72, 96, and 120 h in the absence and presence of AA and/or calcium ionophore (A23187) and 8-iso-PGF2alpha was measured in the culture media. Exposure of primary cultures of AMs to 90% oxygen resulted in a significant increase in 8-iso-PGF2alpha in the media (25 +/- 2 pg/mL) compared with air-exposed controls (14 +/- 1 pg/mL). The addition of 10 microM AA and 2 microM A23187 to the culture media resulted in a marked increase in 8-iso-PGF2alpha production by AMs exposed to air and 90% oxygen. However, treatment of AMs with the combination of AA and A23187, followed by exposure to 90% oxygen for 72 h, resulted in a 27-fold increase in 8-iso-PGF2alpha compared with media alone and 90% oxygen. AMs metabolized free and phospholipid-bound AA to 8-iso-PGF2alpha, an activity enhanced in the 90% oxygen environment. Finally, acetylsalicylic acid, a cyclooxygenase inhibitor and free radical scavenger, reduced but did not abolish production of 8-iso-PGF2alpha. This study provides evidence that AMs produce a free radical-mediated isomeric prostaglandin compound that may be involved in pulmonary oxygen toxicity.

Role of nonenzymatically generated prostanoid, 8-iso-PGF2 alpha, in pulmonary oxygen toxicity.

Oxygen delivery at higher than ambient concentrations is in frequent clinical use, yet prolonged exposure can produce pulmonary edema in humans and animals. The specific mediators of oxygen toxicity are unknown, although evidence suggests that oxygen-based radicals such as superoxide anion contribute to this injury. Recently, 8-iso-prostaglandin F2 alpha (PGF2 alpha), an F2-isoprostane formed by free radical-initiated lipid peroxidation of arachidonic acid, has been implicated in pulmonary injury. Nitric oxide (NO) also contributes to tissue oxygen radical load, and although believed to be beneficial, its metabolites may play a pathophysiological role by participating in lipid peroxidation and isoprostane formation. We hypothesized that 8-iso-PGF2 alpha and NO levels increase in high oxygen concentrations and that 8-iso-PGF2 alpha is associated with lung injury and accumulation of plasma albumin in pulmonary extravascular space. Levels of 8-iso-PGF2 alpha in bronchial alveolar lavage fluid (BALF) of rats exposed to 90% O2 at 1 atmosphere for 48 h (56 +/- 3 pg/ml) or 60 h (70 +/- 5 pg/ml) were significantly increased compared with levels in ambient air-exposed control rats (36 +/- 5 pg/ml). NO levels in BALF of rats exposed to 90% O2 at 1 atmosphere for 60 h were increased 50% compared with NO levels in BALF of rats exposed to ambient air or 48 h of 90% O2 (P < 0.05). Accumulation of radiolabeled plasma albumin in lung parenchyma of rats inhaling 8-iso-PGF2 alpha was also examined.(ABSTRACT TRUNCATED AT 250 WORDS)

Cellular and molecular alterations in the beta adrenergic system with cardiomyopathy induced by tachycardia.

OBJECTIVE: The aim was to examine the relationship between changes in myocyte function to changes in protein and mRNA content of components of the beta adrenergic system with tachycardia induced cardiomyopathy. METHODS: Contractile function and beta adrenergic responsiveness were measured in isolated myocytes from control pigs (n = 6) and in pigs subjected to three weeks of pacing induced supraventricular tachycardia (n = 6). beta Receptor density and affinity, the relative content of the stimulatory (Gs) and inhibitory (Gi) subunits of the G protein complex, and adenylate cyclase activity were determined from sarcolemmal preparations. In order to determine whether these changes were accompanied by alterations in steady state mRNA levels for specific components of the beta adrenergic system, mRNA content for the beta 1 adrenergic receptor and the G alpha s and G alpha i2 subunits of the G protein complex was measured. RESULTS: Chronic supraventricular tachycardia caused a 36% increase in left ventricular end diastolic dimension and a 61% decrease in left ventricular fractional shortening compared to controls. The velocity of isolated myocyte shortening was 50% lower in myocytes from hearts with tachycardia cardiomyopathy than in control myocytes. In the presence of 50 nM isoprenaline or 2 microM forskolin, the velocity of myocyte shortening was 65% lower in the myopathic myocytes than in the controls. With the development of tachycardic cardiomyopathy, beta adrenergic receptor density fell by 25% with no change in affinity, Gs decreased by 35%, and Gi increased by over 50% compared to controls. Basal adenylate cyclase activity and isoprenaline and forskolin stimulated adenylate cyclase activity fell by over 50% with supraventricular tachycardia compared to controls. The relative content of G alpha i2 mRNA increased threefold with the development of tachycardic cardiomyopathy with no change in the relative abundance of mRNA for the beta 1 receptor or G alpha s when compared with controls. CONCLUSIONS: The changes in myocyte beta adrenergic responsiveness with the development of tachycardic cardiomyopathy are due to alterations in cellular mechanisms (decreased beta receptor and Gs density, increased Gi) and in molecular mechanisms (increased Gi mRNA content).