Whether decreasing the local anesthetic concentration during a continuous femoral nerve block results in less quadriceps weakness remains unknown.
Preoperatively, bilateral femoral perineural catheters were inserted in patients undergoing bilateral knee arthroplasty (n = 36) at a single clinical center. Postoperatively, right-sided catheters were randomly assigned to receive perineural ropivacaine of either 0.1% (basal 12 mL/h; bolus 4 mL) or 0.4% (basal 3 mL/h; bolus 1 mL), with the left catheter receiving the alternative concentration/rate in an observer- and subject-masked fashion. The primary endpoint was the maximum voluntary isometric contraction of the quadriceps femoris muscles the morning of postoperative day 2. Equivalence of treatments would be concluded if the 95% confidence interval for the difference fell within the interval of −20% to 20%. Secondary endpoints included active knee extension, passive knee flexion, tolerance to cutaneous electrical current applied over the distal quadriceps tendon, dynamic pain scores, opioid requirements, and ropivacaine consumption.
Quadriceps maximum voluntary isometric contraction for limbs receiving 0.1% ropivacaine was a mean (SD) of 13 (8) N·m, versus 12 (8) N·m for limbs receiving 0.4% [intra-subject difference of 3 (40) percentage points; 95% CI −10 to 17; p = 0.63]. Because the 95% confidence interval fell within prespecified tolerances, we conclude that the effect of the two concentrations were equivalent. Similarly, there were no statistically significant differences in secondary endpoints.
For continuous femoral nerve blocks, we found no evidence that local anesthetic concentration and volume influence block characteristics, suggesting that local anesthetic dose (mass) is the primary determinant of perineural infusion effects.
Many anesthetics reduce lower esophageal sphincter pressure (LESP) and consequently the gastro-esophageal pressure gradient (GEPG); thus they may promote gastro-esophageal reflux and contribute to aspiration pneumonia. Our goals were to evaluate the association between LESP and 2 measures of sedation: bispectral index (BIS) and the responsiveness component of the Observer’s Assessment of Alertness score (OAA/S).
Eleven healthy volunteers were each sedated on 2 separate days. Subjects were given sedative infusions of increasing target plasma concentrations of dexmedetomidine or propofol. LESP and GEPG were recorded after starting each infusion phase. Generalized estimating equation modeling was used to assess the relationship between LESP and, respectively, BIS and OAA/S. The existence of a drug-dependent association was evaluated within these models by testing an interaction term. Wald tests were used to evaluate the relationships within the models.
We found a significant relationship between LESP and BIS (P=0.0043) after adjusting for the main effect of sedative type – a deepening of sedation as measured by a decrease in BIS of 10% was associated with a decrease [Bonferroni-adjusted 95% CI] in LESP of −1.34 [−2.39, −0.29] mmHg. After adjusting for the main effect of sedative drug, LESP significantly declined with declining OAA/S (P=0.001); a unit decrease of OAA/S was associated with a decrease [Bonferroni-adjusted 95% CI] in LESP of −2.01 [−3.20, −0.81] mmHg.
Deeper sedation, as measured by either BIS or OAA/S, significantly reduces LESP.
BIS; lower esophageal sphincter; dexmedetomidine; propofol
Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature measuring sites are completely non-invasive and easy to use — especially in patients not having general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients having general anesthesia exceeding 30 minutes in duration, and in patients having major operations under neuraxial anesthesia.
Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature triggering cold defenses including arterio-venous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, and the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extant than general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.
Acupuncture and related techniques are increasingly practiced in conventional medical settings, and the number of patients willing to use these techniques is increasing. Despite more than 30 years of research, the exact mechanism of action and efficacy of acupuncture have not been established. Furthermore, most aspects of acupuncture have yet to be adequately tested. There thus remains considerable controversy about the role of acupuncture in clinical medicine.
Acupuncture apparently does not reduce volatile anesthetic requirement by a clinically important amount. However, preoperative sedation seems to be a promising application of acupuncture in perioperative settings. Acupuncture may be effective for postoperative pain relief but requires a high level of expertise by the acupuncture practitioner. Acupuncture and related techniques can be used for treatment and prophylaxis of postoperative nausea and vomiting in routine clinical practice in combination with, or as an alternative to, conventional antiemetics when administered before induction of general anesthesia.
Summary Statement: The use of acupuncture for perioperative analgesia, nausea and vomiting, sedation, anesthesia, and complications is reviewed.
A new surgical drape, which is impervious to moisture, presumably reduces evaporative heat loss. We compared cutaneous heat loss and skin temperature in volunteers covered with this drape to two conventional surgical drapes (Large Surgical Drape and Medline Proxima). With IRB approval and informed consent, we calculated cutaneous heat loss and skin-surface temperatures from 15 area-weighted thermal flux transducers in 8 volunteers. In random order, each of the drapes was evaluated with dry transducers and moistened transducers (simulating wet skin). After a 20-minute uncovered control period, volunteers were covered from the neck down for 40 minutes. Data were recorded continuously and averaged over 10-minutes. Results were similar for all three drapes for dry or moist conditions. Under dry conditions, baseline heat loss was 82±14 watts (W) and decreased 30% with a surgical drape (P<0.001). Under moist conditions, baseline heat loss was 231±45 W and decreased 29% with a drape covering (P<0.001). Moist skin increased heat loss 282% (P<0.001). There were no clinically important differences in skin temperature among the covers with dry or moist skin. Moist skin increased heat loss nearly three-fold, but there were no differences among the drapes. We conclude that loss is comparable with impervious and conventional drapes with either moist or dry skin.
Evaporation; Heat flux; Insulation; Surgical drapes; Sweat; Temperature; Thermoregulation
Women generally report greater sensitivity to pain than do men, and healthy young women require 20% more anesthetic than healthy age-matched men to prevent movement in response to noxious electrical stimulation. In contrast, MAC for xenon is 26% less in elderly Japanese women than in elderly Japanese men. Whether anesthetic requirement is similar in men and women thus remains in dispute. We therefore tested the hypothesis that the desflurane concentration required to prevent movement in response to skin incision (MAC) differs in men and women.
Using the Dixon “up and down” method, we determined MAC for desflurane in 15 female and 15 male patients undergoing surgery (18–40 yr).
MAC was 6.2 ± 0.4% desflurane for women vs. 6.0 ± 0.3% for men (P = 0.31), a difference of only 3%. These data provide 90% power to detect a 9% difference between the groups.
MAC of desflurane did not differ between young men and women undergoing surgery with a true surgical incision. While pain sensitivity may differ in women versus men, MAC of desflurane does not.
MAC for desflurane was similar in young adult women and men (6.2 ± 0.4% desflurane for women vs. 6.0 ± 0.3% for men; P = 0.31). This contrasts with previous results in which anesthetic requirement was based on the response to electrical stimulation and with studies showing that women report more pain than men.
OBJECTIVE: To test the hypothesis that perioperative transfusion of allogeneic and autologous red blood cells (RBCs) stored for a prolonged period speeds biochemical recurrence of prostate cancer after prostatectomy.
PATIENTS AND METHODS: We evaluated biochemical prostate cancer recurrence in men who had undergone radical prostatectomy and perioperative blood transfusions from July 6, 1998, through December 27, 2007. Those who received allogeneic blood transfusions were assigned to nonoverlapping “younger,” “middle,” and “older” RBC storage duration groups. Those who received autologous RBC transfusions were analyzed using the maximum storage duration as the primary exposure. We evaluated the association between RBC storage duration and biochemical recurrence using multivariable Cox proportional hazards regression.
RESULTS: A total of 405 patients received allogeneic transfusions. At 5 years, the biochemical recurrence–free survival rate was 74%, 71%, and 76% for patients who received younger, middle, and older RBCs, respectively; our Cox model indicated no significant differences in biochemical recurrence rates between the groups (P=.82; Wald test). Among patients who received autologous transfusions (n=350), maximum RBC age was not significantly associated with biochemical cancer recurrence (P=.95). At 5 years, the biochemical recurrence–free survival rate was 85% and 81% for patients who received younger and older than 21-day-old RBCs, respectively.
CONCLUSION: In patients undergoing radical prostatectomy who require RBC transfusion, recurrence risk does not appear to be independently associated with blood storage duration.
The authors evaluated the association between duration of red blood cell storage and biochemical recurrence of cancer in men who had undergone radical prostatectomy and perioperative blood transfusions. Recurrence risk does not appear to be independently associated with blood storage duration.
α2-Agonists are a novel class of drugs with mechanisms of action that differ from other commonly used anesthetic drugs. They have neuroprotective, cardioprotective, and sedative effects. These unique characteristics make them potentially useful during neuroanesthesia and intensive care. We review the effects of dexmedetomidine on cerebral blood flow and cerebral metabolism, along with recent advances in using α2-agonists in neuroanesthesia and neurointensive care.
Alpha-2 agonist; anesthesia; dexmedetomidine; neuroanesthesia; neuroprotection
Objective To determine which bedside method of detecting inadvertent endobronchial intubation in adults has the highest sensitivity and specificity.
Design Prospective randomised blinded study.
Setting Department of anaesthesia in tertiary academic hospital.
Participants 160 consecutive patients (American Society of Anesthesiologists category I or II) aged 19-75 scheduled for elective gynaecological or urological surgery.
Interventions Patients were randomly assigned to eight study groups. In four groups, an endotracheal tube was fibreoptically positioned 2.5-4.0 cm above the carina, whereas in the other four groups the tube was positioned in the right mainstem bronchus. The four groups differed in the bedside test used to verify the position of the endotracheal tube. To determine whether the tube was properly positioned in the trachea, in each patient first year residents and experienced anaesthetists were randomly assigned to independently perform bilateral auscultation of the chest (auscultation); observation and palpation of symmetrical chest movements (observation); estimation of the position of the tube by the insertion depth (tube depth); or a combination of all three (all three).
Main outcome measures Correct and incorrect judgments of endotracheal tube position.
Results 160 patients underwent 320 observations by experienced and inexperienced anaesthetists. First year residents missed endobronchial intubation by auscultation in 55% of cases and performed significantly worse than experienced anaesthetists with this bedside test (odds ratio 10.0, 95% confidence interval 1.4 to 434). With a sensitivity of 88% (95% confidence interval 75% to 100%) and 100%, respectively, tube depth and the three tests combined were significantly more sensitive for detecting endobronchial intubation than auscultation (65%, 49% to 81%) or observation(43%, 25% to 60%) (P<0.001). The four tested methods had the same specificity for ruling out endobronchial intubation (that is, confirming correct tracheal intubation). The average correct tube insertion depth was 21 cm in women and 23 cm in men. By inserting the tube to these distances, however, the distal tip of the tube was less than 2.5 cm away from the carina (the recommended safety distance, to prevent inadvertent endobronchial intubation with changes in the position of the head in intubated patients) in 20% (24/118) of women and 18% (7/42) of men. Therefore optimal tube insertion depth was considered to be 20 cm in women and 22 cm in men.
Conclusion Less experienced clinicians should rely more on tube insertion depth than on auscultation to detect inadvertent endobronchial intubation. But even experienced physicians will benefit from inserting tubes to 20-21 cm in women and 22-23 cm in men, especially when high ambient noise precludes accurate auscultation (such as in emergency situations or helicopter transport). The highest sensitivity and specificity for ruling out endobronchial intubation, however, is achieved by combining tube depth, auscultation of the lungs, and observation of symmetrical chest movements.
Trial registration NCT01232166.
The objective of this study was to determine the prevalence of select microorganisms in oral biofilms and to investigate relationships between oral and respiratory status in persons with mental retardation/intellectual and developmental disabilities (IDD).
We conducted a 6-month-long observational cohort study with 63 persons with IDD. Oral examinations, oral sampling, and medical record reviews were performed at baseline and then monthly. Polymerase chain reaction (PCR) was used to analyze all baseline oral samples for the presence of Streptococcus pneumoniae (S. pneumoniae), Methicillin-Resistant Staphylococcus aureus (MRSA), Prevotella melaninogenica (P. melaninogenica) and Candida albicans (C. albicans). PCR analyses were also performed on participants’ samples collected in the month prior to being diagnosed with a respiratory infection.
All subjects had P. melaninogenica detected by PCR in their oral samples. Fifty-five percent (35 of 63) of participants had S. pneumoniae, MRSA and C. albicans in their oral samples at baseline. No dental decay was detected clinically, oral hygiene was fair, and dysphagia was common. During the 6 months of the study, there were 22 respiratory infections (35% of participants) – 12 pneumonias, 7 sinusitis, 1 bronchitis, and 1 upper respiratory tract infection. Participants with microorganisms in their baseline samples were significantly more likely to develop any respiratory infection and those who had poor oral status were significantly more likely to develop pneumonia. Almost 60% of participants who developed respiratory infections had the same microorganism detected in the sample collected in the month prior to infection as had been detected in their baseline sample.
Potentially pathogenic microorganisms in the oral cavity and poor oral status significantly increased the risk of developing respiratory infections, including pneumonia, in persons with IDD. The results suggest that colonization with these microorganisms may persist despite routine tooth brushing. Meticulous comprehensive oral hygiene of the oral cavity may be needed to reduce oropharyngeal microbial load.
We previously reported that extending an overnight continuous posterior lumbar plexus nerve block to 4 days after hip arthroplasty provides clear benefits during the perineural infusion in the immediate postoperative period. However, it remains unknown if the extended infusion improves subsequent health-related quality-of-life.
Patients undergoing hip arthroplasty received a posterior lumbar plexus perineural infusion of ropivacaine 0.2% from surgery until the following morning, at which time patients were randomized to either continue perineural ropivacaine (n=24) or normal saline (n=23) in a double-masked fashion. Patients were discharged with their catheter and a portable infusion pump, and catheters were removed on postoperative day 4. Health-related quality-of-life was measured using the Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index preoperatively and then at 7 days, as well as 1, 2, 3, 6, and 12 months after surgery. The WOMAC evaluates 3 dimensions of health-related quality-of-life: pain, stiffness, and physical functional disability (global score of 0–96, lower scores indicate lower levels of symptoms or physical disability). For inclusion in the primary analysis, we required a minimum of 3 of the 6 time points, including day 7 and at least 2 of months 3, 6, and 12.
The 2 treatment groups had similar global WOMAC scores for the mean area under the curve calculations (point estimate for the difference in mean area under the curve for the 2 groups [extended infusion group – overnight infusion group] = 0.8, 95% confidence interval: −5.3 to +6.8 [−5.5% to +7.1%]; p=0.80) and at all individual time points (p>0.05).
This investigation found no evidence that extending an overnight continuous posterior lumbar plexus nerve block to 4 days improves (or worsens) subsequent health-related quality-of-life between 7 days and 12 months after hip arthroplasty.
It remains unclear whether local anesthetic concentration or total drug dose is the primary determinant of continuous peripheral nerve block effects. The only previous investigation, involving continuous popliteal-sciatic nerve blocks, specifically addressing this issue reported that insensate limbs were far more common with higher volumes of relatively dilute ropivacaine compared with lower volumes of relatively concentrated ropivacaine. However, it remains unknown if this relationship is specific to the sciatic nerve in the popliteal fossa or whether it varies depending on anatomic location. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates, but at an equal total basal dose, produces comparable effects when used in a continuous infraclavicular brachial plexus block.
Preoperatively, an infraclavicular catheter was inserted using the coracoid approach in patients undergoing moderately painful orthopedic surgery distal to the elbow. Patients were randomly assigned to receive a postoperative perineural ropivacaine infusion of either 0.2% (basal 8 mL/h, bolus 4 mL) or 0.4% (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Both groups, therefore, received 16 mg of ropivacaine each hour with a possible addition of 8 mg every 30 min via a patient-controlled bolus dose. Our primary end point was the incidence of an insensate limb during the 24-h period beginning the morning after surgery. Secondary end points included analgesia and patient satisfaction.
Patients given 0.4% ropivacaine (n = 27) experienced an insensate limb, a mean (sd) of 1.8 (1.6) times, compared with 0.6 (0.9) times for subjects receiving 0.2% ropivacaine (n = 23; estimated difference = 1.2 episodes, 95% confidence interval, 0.5–1.9 episodes; P = 0.001). Satisfaction with postoperative analgesia (scale 0–10, 10 = highest) was scored a median (25th–75th percentiles) of 10.0 (8.0–10.0) in Group 0.2% and 7.0 (5.3–8.9) in Group 0.4% (P = 0.018). Analgesia was similar in each group.
For continuous infraclavicular nerve blocks, local anesthetic concentration and volume influence perineural infusion effects in addition to the total mass of local anesthetic administered. Insensate limbs were far more common with smaller volumes of relatively concentrated ropivacaine. This is the opposite of the relationship previously reported for continuous popliteal-sciatic nerve blocks. The interaction between local anesthetic concentration and volume is thus complex and varies among catheter locations.
Background and Objectives:
It is currently unknown if the primary determinant of continuous peripheral nerve block effects is simply total drug dose, or whether local anesthetic concentration and/or volume have an influence. We therefore tested the null hypothesis that providing ropivacaine at different concentrations and rates—but at an equal total basal dose—produces similar effects when used in a continuous interscalene nerve block.
Preoperatively, an interscalene perineural catheter was inserted using the anteriolateral approach in patients undergoing moderately painful shoulder surgery. Subjects were randomly assigned to receive a postoperative perineural infusion of either 0.2% ropivacaine (basal 8 mL/h, bolus 4 mL) or 0.4% ropivacaine (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Our primary end point was the incidence of an insensate hand/finger during the 24-hours beginning the morning following surgery.
The incidence of an insensate hand/finger did not differ between the treatment groups (n=50) to a statistically significant degree (0.2% ropivacaine mean [SD] of 0.8 [1.3] times; 0.4% ropivacaine mean 0.3 [0.6] times; estimated difference=0.5 episodes, 95% confidence interval, −0.1 to 1.1 episodes; p=0.080). However, this is statistically inconclusive given the confidence interval. In contrast, pain (p=0.020) and dissatisfaction (p=0.011) were greater in patients given 0.4% ropivacaine.
For continuous interscalene nerve blocks, the 95% confidence interval (plausible differences in the incidence of an insensate hand/finger) contains values ranging from a clinically important disadvantage (1.1) to a clinically unimportant advantage (−0.1) for the lower concentration. Given the statistically inconclusive results and design limitations of the current study, further research on this issue is warranted. In contrast, providing a lower concentration of local anesthetic at a higher basal rate provided superior analgesia. These relationships are different than previously reported for continuous popliteal-sciatic nerve blocks. The interaction between local anesthetic concentration and volume is thus complex and varies among catheter locations.
anesthesia; continuous peripheral nerve block; continuous interscalene nerve block; patient-controlled regional analgesia; perineural local anesthetic infusion
The authors tested the hypotheses that after hip arthroplasty, ambulation distance is increased and the time required to reach three specific readiness-for-discharge criteria is shorter with a 4-day ambulatory continuous lumbar plexus block (cLPB) than with an overnight cLPB.
A cLPB consisting of 0.2% ropivacaine was provided from surgery until the following morning. Patients were then randomly assigned either to continue ropivacaine or to be switched to normal saline. Primary endpoints included (1) time to attain three discharge criteria (adequate analgesia, independence from intravenous analgesics, and ambulation ≥ 30 m) and (2) ambulatory distance in 6 min the afternoon after surgery. Patients were discharged with their cLPB and a portable infusion pump, and catheters were removed on the fourth postoperative day.
Patients given 4 days of perineural ropivacaine (n = 24) attained all three discharge criteria in a median (25th-75th percentiles) of 29 (24-45) h, compared with 51 (42-73) h for those of the control group (n = 23; estimated ratio = 0.62; 95% confidence interval, 0.45-0.92;P = 0.011). Patients assigned to receive ropivacaine ambulated a median of 34 (9-55) m the afternoon after surgery, compared with 20 (6-46) m for those receiving normal saline (estimated ratio = 1.3; 95% confidence interval, 0.6-3.0;P = 0.42). Three falls occurred in subjects receiving ropivacaine (13%),versusnone in subjects receiving normal saline.
Compared with an overnight cLPB, a 4-day ambulatory cLPB decreases the time to reach three predefined discharge criteria by an estimated 38% after hip arthroplasty. However, the extended infusion did not increase ambulation distance to a statistically significant degree.
It remains unknown whether local anesthetic concentration, or simply total drug dose, is the primary determinant of continuous peripheral nerve block effects. We therefore tested the null hypothesis that providing different concentrations and rates of ropivacaine, but at equal total doses, produces comparable effects when used in a continuous sciatic nerve block in the popliteal fossa.
Preoperatively, a perineural catheter was inserted adjacent to the sciatic nerve using a posterior popliteal approach in patients undergoing moderately painful orthopedic surgery at or distal to the ankle. Postoperatively, patients were randomly assigned to receive a perineural ropivacaine infusion of either 0.2% (basal 8 mL/h, bolus 4 mL) or 0.4% (basal 4 mL/h, bolus 2 mL) through the second postoperative day. Therefore, both groups received 16 mg of ropivacaine each hour with a possible addition of 8 mg every 30 min via a patient-controlled bolus dose. The primary end point was the incidence of an insensate limb, considered undesirable, during the 24-h period beginning the morning after surgery. Secondary end points included analgesia and patient satisfaction.
Patients given 0.2% ropivacaine (n = 25) experienced an insensate limb with a mean (sd) of 1.8 (1.8) times, compared with 0.6 (1.1) times for subjects receiving 0.4% ropivacaine (n = 25; estimated difference = 1.2 episodes, 95% confidence interval, 0.3–2.0 episodes; P = 0.009). In contrast, analgesia and satisfaction were similar in each group.
For continuous popliteal-sciatic nerve blocks, local anesthetic concentration and volume influence block characteristics. Insensate limbs were far more common with larger volumes of relatively dilute ropivacaine. During continuous sciatic nerve block in the popliteal fossa, a relatively concentrated solution in smaller volume thus appears preferable.
Quantitative sensory testing (QST), which allows a better characterization of sensory deficits and painful symptoms, may offer additional information on the pathophysiology of postoperative pain.
Twenty patients scheduled for total knee anthroplasty were evaluated clinically and with QST before surgery, at one and four days, and at one and four months after surgery. Clinical evaluation included preoperative pain and inflammation of operative knee, postoperative assessment of pain at rest and during movement (Visual Analog Scale score), cumulative morphine consumption, and circumference and temperature of both knees. QST included thermal and mechanical (pressure) pain threshold measurements and assessment of responses to suprathreshold stimuli. Brush-evoked allodynia was also evaluated. Measurements were taken on the operative knee, contra lateral knee, and on the hand as a control site.
All patients had prolonged and severe pain before surgery and inflammation of operative knee. Preoperative OST provided evidence of heat hyperalgesia in the inflammatory area on the operative knee, but absence of punctate or brush-evoked allodynia in the adjacent non inflamed area. Patients had intense postoperative pain, mostly induced by movement. Primary heat hyperalgesia was present on the operative knee on the first and fourth days after surgery, and was associated with punctate mechanical allodynia in the inflammatory area, but not in the adjacent non inflamed area. Postoperative morphine consumption was correlated with preoperative heat hyperalgesia (r=0.63; P=0.01). QST was normalyzed at the 4-month evaluation and only 4 patients had moderate knee pain induced by movement at that time.
Heat hyperalgesia was the predominant OST symptom associated with perioperative pain after total knee arthroplastv and was predictive of postoperative morphine consumption
Aged; Analgesia, Patient-Controlled; Analgesics, Opioid; administration & dosage; Arthritis; pathology; physiopathology; surgery; Arthroplasty, Replacement, Knee; Female; Heat; Humans; Hyperalgesia; pathology; physiopathology; Knee; pathology; physiopathology; surgery; Male; Morphine; administration & dosage; Pain Measurement; Pain Threshold; Pain, Postoperative; drug therapy; physiopathology; Postoperative Care; Preoperative Care; Prospective Studies; Severity of Illness Index; Time Factors; Treatment Outcome
Parecoxib, a selective cyclooxygenase-2 inhibitor, may reduce postoperative pain when administered before surgery without increasing bleeding.
We randomly assigned 62 patients scheduled for total hip arthroplasty to the following intravenous dosing schedule: 1) placebo at induction, at wound closure, and 12 hours after induction (control); 2) parecoxib 40 mg at induction, placebo at wound closure, and parecoxib 40 mg 12 hours after induction (pre); or, 3) placebo at induction, parecoxib 40 mg at wound closure, and parecoxib 40 mg 12 hours after induction (post). Pain scores at rest and with movement recorded every 4 hours for 24 hours using a visual analog scale. Treatment side effects were recorded every 4 hours. Red cell loss for 5 days after surgery was calculated.
Postoperative pain scores were less in pre and post groups than in the control group. Postoperative bleeding was similar in the three groups. There were no significant differences between pre and post groups, nor was their any trend suggesting a pre-emptive analgesic efficacy from preincision administration of parecoxib. Morphine use in the Post Anesthesia Care Unit was reduced in the pre and post groups compared with the control group (14.2±2.0, and 15.7±2.0, versus 20.4±2.3 mg), although the trend was only significant (p < 0.05) in the pre group. The first pain score was also reduced in the pre and post groups compared to the control group (56.1±7.5 and 64.2 ± 7.0 versus 78.3±5), but this was also only significant for the pre group (p=0.001). The delay for first analgesic demand was increased for both the pre and post group compared to the control group (38±9 and 28.2 ± 6.6 versus 18±6 min), but again this was only significant for the pre group (P=0.05). Twenty-four hour consumption of morphine was similar in the pre (26±12 mg) and post groups (25±13 mg); both of which were significantly less than control group (47±27 mg, P<0.001).
Administration of parecoxib before hip arthroplasty did not provide preemptive analgesia. There was a trend towards improved analgesia immediately after surgery with preincision administration, consistent with the expected time course of NSAID drug effect. Perioperative parecoxib administration, consisting of two injections spaced 12 hours apart, improved postoperative analgesia over the first 24 hours without increasing bleeding.
anesthesia; analgesia; parecoxib; preemptive analgesia; coagulation; bleeding; Aged; Analgesia; methods; Arthroplasty, Replacement, Hip; Female; Humans; Isoxazoles; administration & dosage; Male; Middle Aged; Orthopedic Procedures; methods; Pain, Postoperative; drug therapy; epidemiology; Time Factors
In addition to their antimicrobial activity, antibiotics modulate cellular host defence. Granulocyte-colony stimulating factor (G-CSF) is also a well known immunomodulator; however little is known about the interactions of G-CSF with antibiotics. We investigated in septic rats the effects of two antibiotic combinations with G-CSF.
In two clinic modelling randomised trials (CMRTs), male Wistar rats were anesthetized, given antibiotic prophylaxis, had a laparotomy with peritoneal contamination and infection (PCI), and were randomly assigned (n = 18 rats/group) to: 1) PCI only; 2) PCI+antibiotic; and, 3) PCI+antibiotic+G-CSF prophylaxis (20 μg/kg, three times). This sequence was conducted first with 10 mg/kg coamoxiclav, and then with ceftriaxone/metronidazole (Cef/met, 10/3 mg/kg). In additional animals, the blood cell count, migration and superoxide production of PMNs, systemic TNF-α and liver cytokine mRNA expression levels were determined.
Only the combination coamoxiclav plus G-CSF improved the survival rate (82 vs. 44%, p < 0.001). Improved survival with this combination was accompanied by normalised antimicrobial PMN migratory activity and superoxide production, along with normalised systemic TNF-α levels and a reduced expression of TNF-α and IL-1 in the liver.
There are substantial differences in the interaction of antibiotics with G-CSF. Therefore, the selection of the antibiotic for combination with G-CSF in sepsis treatment should be guided not only by the bacteria to be eliminated, but also by the effects on antimicrobial functions of PMNs and the cytokine response.
Background: Mean-body temperature (MBT) is the mass-weighted average temperature of body tissues. Core temperature is easy to measure, but direct measurement of peripheral tissue temperature is painful, risky, and requires complex calculations. Alternatively MBT can be estimated from core and mean skin temperatures with a formula proposed by Burton in 1935: MBT = 0.64. TCore + 0.36. TSkin. This formula remains widely used, but not been validated in the perioperative period and seems unlikely to remain accurate in dynamic perioperative conditions such as cardiopulmonary bypass. We thus tested the hypothesis that MBT, as estimated with Burton’s formula, poorly estimates measured MBT at a temperature range between 18 and 36.5° C.
Materials and Methods: We re-evaluated four of our previously published studies in which core and mass-weighted mean peripheral tissue temperatures were measured in patients undergoing substantial thermal perturbations. Peripheral compartment temperatures were estimated using fourth-order regression and integration over volume from 18 intramuscular needle thermocouples, 9 skin temperatures, and "deep" hand and foot temperature. MBT was determined from mass-weighted average of core and peripheral tissue temperatures and estimated from core temperature and mean skin temperature (15 area-weighted sites) using Burton’s formula.
Results: 913 data pairs from 44 study subjects were included in the analysis. Measured MBT ranged from 18 to 36.5°C. There was a remarkably good relationship between measured and estimated MBT: MBTmeasured = 0.94 · MBTestimated + 2.15, r2 = 0.98. Differences between the estimated and measured values averaged -0.09 ± 0.42°C.
Conclusions: We concluded that estimation of MBT from mean skin and core temperatures is generally accurate and precise.
Risk of wound infection is increased in morbidly obese surgical patients, in part because a major determinant of wound infection risk, tissue oxygenation, is marginal. Unlike in lean patients, supplemental inspired oxygen (FIO2) only slightly improves tissue oxygenation in obese patients. Mild hypercapnia improves tissue oxygenation in lean, but has not been evaluated in obese patients. We thus tested the hypothesis that mild hypercapnia markedly improves tissue oxygenation in morbidly obese patients given FIO2 80% during major abdominal surgery. Thirty obese patients (body mass index 61.5±17 kg/m2) scheduled for open gastric bypass were randomly assigned to normocapnia (n=15, end-tidal PCO2 35 mmHg) or hypercapnia (n=15, end-tidal PCO2 50 mmHg); FIO2 was 80%. Anesthetic management and other confounding factors were controlled. Tissue oxygen tension was measured subcutaneously at the upper arm using a polarographic probe in a silastic tonometer. Demographic characteristics, cardiovascular measurements, and PaO2 (222±48 versus 230±68 mmHg in normocapnic versus hypercapnic; mean±SD, P=0.705) were comparable in the groups. Tissue oxygen tension, however, was greater in hypercapnic than in normocapnic patients (78±31 versus 56±13 mmHg, P=0.029). Mild hypercapnia increased tissue oxygenation by an amount believed to be clinically important and could potentially reduce the risk of surgical wound infection in morbidly obese patients.
obesity; hypercapnia; tissue oxygenation; and wound infection
We determined the effects of doxapram on the major autonomic thermoregulatory responses in humans. Nine healthy volunteers were studied on two days: Control and Doxapram (intravenous infusion to a plasma concentration of 2.4 ±0.8 μg/mL, 2.5 ±0.9 μg/mL, and 2.6 ±1.1 μg/mL at the sweating, vasoconstriction, and shivering thresholds, respectively). Each day, skin and core temperatures were increased to provoke sweating, then reduced to elicit peripheral vasoconstriction and shivering. We determined the sweating, vasoconstriction, and shivering thresholds with compensation for changes in skin temperature. Data were analyzed with paired t tests and presented as means ± SDs; P < 0.05 was considered statistically significant. Doxapram did not change the sweating (Control: 37.5±0.4°C, Doxapram: 37.3±0.4°C, P=0.290) or the vasoconstriction threshold (36.8±0.7 vs. 36.4±0.5°C; P=0.110). However, it significantly reduced the shivering threshold from 36.2±0.5 to 35.7±0.7°C (P=0.012). No sedation or symptoms of panic were observed on either study day. The observed reduction in the shivering threshold explains the drug's efficacy for treatment of postoperative shivering; however, a reduction of only 0.5°C is unlikely to markedly facilitate induction of therapeutic hypothermia as a sole agent.
Anesthesia; Hypothermia; Temperature; Thermoregulation
Background: Anesthetic requirement in redheads is exaggerated, suggesting that redheads may be especially sensitive to pain. We therefore tested the hypotheses that women with natural red hair are more sensitive to pain, and that redheads are resistant to topical and subcutaneous lidocaine.
Methods: We evaluated pain sensitivity in red-haired (n=30) or dark-haired (n=30) women by determining the electrical current perception threshold, pain perception, and maximum pain tolerance with a Neurometer CPT/C (Neurotron, Inc., Baltimore, MD). We evaluated the analogous warm and cold temperature thresholds with the TSA-II Neurosensory Analyzer (Medoc Ltd., Minneapolis, MN). Volunteers were tested with both devices at baseline and with the Neurometer after 1-hour exposure to 4% liposomal lidocaine and after subcutaneous injection of 1% lidocaine. Data are presented as medians [interquartile ranges].
Results: Current perception, pain perception, and pain tolerance thresholds were similar in the red-haired and dark-haired women at 2000, 250, and 5 Hz. In contrast, redheads were more sensitive to cold pain perception (22.6°C [15.1, 26.1] vs. 12.6°C [0, 20], P=0.004), cold pain tolerance (6.0°C [0, 9.7] vs. 0.0°C [0.0, 2.0], P=0.001), and heat pain (46.3°C [45.7, 47.5] vs. 47.7°C [46.6, 48.7], P=0.009). Subcutaneous, lidocaine was significantly less effective in redheads, e.g., pain tolerance threshold at 2000 Hz stimulation in redheads was 11.0 mA [8.5, 16.5] vs. >20.0 mA [14.5, >20] in others, P=0.005).
Conclusion: Red hair is the phenotype for mutations of the melanocortin 1 receptor. Our results indicate that redheads are more sensitive to thermal pain and are resistant to the analgesic effects of subcutaneous lidocaine. Mutations of the melanocortin 1 receptor, or a consequence thereof, thus modulate pain sensitivity.