Mandibular muscle troponin of the Florida carpenter ant Camponotus floridanus: extending our insights into invertebrate Ca2+ regulation

Ants use their mandibles for a variety of functions and behaviors. We investigated mandibular muscle structure and function from major workers of the Florida carpenter ant Camponotus floridanus: force-pCa relation and velocity of unloaded shortening of single, permeabilized fibres, primary sequences of troponin subunits (TnC, TnI and TnT) from a mandibular muscle cDNA library, and muscle fibre ultrastructure. From the mechanical measurements, we found Ca²⁺-sensitivity of isometric force was markedly shifted rightward compared with vertebrate striated muscle. From the troponin sequence results, we identified features that could explain the rightward shift of Ca²⁺-activation: the N-helix of TnC is effectively absent and three of the four EF-hands of TnC (sites I, II and III) do not adhere to canonical sequence rules for divalent cation binding; two alternatively spliced isoforms of TnI were identified with the alternatively spliced exon occurring in the region of the IT-arm α-helical coiled-coil, and the N-terminal extension of TnI may be involved in modulation of regulation, as in mammalian cardiac muscle; and TnT has a Glu-rich C-terminus. In addition, a structural homology model was built of C. floridanus troponin on the thin filament. From analysis of electron micrographs, we found thick filaments are almost as long as the 6.8 μm sarcomeres, have diameter of ~ 16 nm, and typical center-to-center spacing of ~ 46 nm. These results have implications for the mechanisms by which mandibular muscle fibres perform such a variety of functions, and how the structure of the troponin complex aids in these tasks.

Comparison of postoperative pain management using two patient-controlled analgesia methods: nursing perspective

AIM

To compare the effect of fentanyl iontophoretic transdermal system and morphine intravenous patient-controlled analgesia on the time-efficiency and convenience of postoperative patient care.

BACKGROUND

Intravenous patient-controlled analgesia with morphine is effectively used to manage postoperative pain; however, it takes time to set up and administer.

METHODS

Nurses evaluated patient-care tasks with fentanyl iontophoretic transdermal system and/or morphine intravenous patient-controlled analgesia in two phase IIIb studies (n = 1305) using a nurse ease-of-care questionnaire. A responder for time-efficiency and convenience responded with one of the top three positive choices on all items; for satisfaction, a responder chose one of the top two positive choices on both items. Data were collected between March 2004 and April 2005.

FINDINGS

In both studies, greater proportions of nurses were responders for fentanyl iontophoretic transdermal system than for morphine intravenous patient-controlled analgesia, respectively, for time-efficiency [total hip replacement surgery, 80.9% (250/309) vs. 57.7% (172/298), P < 0.001; abdominal/pelvic surgery, 84.8% (162/191) vs. 57.7% (113/196), P < 0.001], convenience [total hip replacement surgery, 85.5% (271/317) vs. 64.1% (191/298), P < 0.001; abdominal/pelvic surgery, 89.2% (166/186) vs. 62.8% (123/196), P < 0.001], and satisfaction [total hip replacement surgery, 66.6% (247/371) vs. 33.3% (108/324), P < 0.001; abdominal/pelvic surgery, 67.4% (155/230) vs. 38.2% (84/220), P < 0.001]. Higher proportions of nurses favoured fentanyl iontophoretic transdermal system than morphine intravenous patient-controlled analgesia in both studies (P < 0.001).

CONCLUSION

The fentanyl iontophoretic transdermal system appears to be simpler, easier to use, and more satisfactory for nurses than morphine intravenous patient-controlled analgesia.

Clinical Staff Resource Use With Intravenous Patient-Controlled Analgesia in Acute Postoperative Pain Management: Results From a Multicenter, Prospective, Observational Study

The purpose of this study was to evaluate hospital resource utilization associated with intravenous patient-controlled analgesia (IV-PCA), with a focus on nursing, pharmacy, and central supply/engineering time spent from a hospital perspective. Data were collected during a multicenter (29 sites), prospective observational study in the United States of subjects who underwent total knee replacement (TKR), total hip replacement (THR), or abdominal hysterectomy (AH) and were administered analgesia through IV PCA for the management of acute postoperative pain. Nursing staff recorded the IV PCA-related tasks they performed for a subject and the duration of time required to perform each task from initial IV PCA set-up to discontinuation. Hospital administrators, nursing managers, central supply/engineering staff, and pharmacy directors were interviewed to obtain data regarding other IV PCA labor resource use. The distribution of surgery type among the 457 subjects was 31.1% THR, 35.9% TKR, and 33.0% AH. The average duration of IV PCA use was 32.6 hours. Nurses reported having to perform an average of 39.6 IV PCA-related tasks, which required an average of 67.4 minutes. The most common IV PCA-related tasks were evaluating pump use and settings, assessing the IV site, evaluating and addressing analgesia side effects, instructing/reinstructing the subject on use, administering supplemental pain medications, assisting with self-care or moving the subject, and assisting the subject with use of the button. Pharmacists reported that they spend approximately 7.9 minutes and pharmacy technicians spend approximately 9.8 minutes, per subject daily course of IV PCA therapy, on the following tasks: checking and verifying the order, doing inventory of the analgesia, preparing the analgesia (ie, filling reservoirs), checking the analgesia, and delivering the analgesia to the nursing units. In addition, pharmacists and RNs spend an average of 47.3 and 40.7 minutes per year in IV PCA-related training. Intravenous patient-controlled analgesia postoperative care requires coordination and involvement of numerous hospital departments. It is labor intensive and involves numerous time-consuming tasks, oversight of IV PCA, and ongoing training. Alternative methods of patient-controlled pain management with similar efficacy that reduces labor resource utilization may be warranted.

Improving Patient and Nurse Outcomes: A Comparison of Nurse Tasks and Time Associated With Two Patient-Controlled Analgesia Modalities Using Delphi Panels

Increased demand on nursing time may adversely affect nurse satisfaction and patient outcomes. Technologies to reduce nursing time and burden may improve patient care. Two Delphi panels assessed the perceived nursing time of fentanyl iontophoretic transdermal system (ITS) and intravenous patient-controlled analgesia (IV PCA) for postoperative pain management. The panels were asked to estimate the time spent on individual nursing tasks from a list. The Clinical Trial panel (n = 14) was composed of nurses who participated in two clinical trials, and data for both PCA modalities were collected from this panel. The routine practice panel (n = 13) was composed of nurses from various hospital units, and only data for IV PCA were collected from this panel. From the Clinical Trial panel, the estimated total average task time was 251 minutes for IV PCA and 210 minutes for fentanyl ITS. From the Routine Practice panel, the estimated total average task time was 163 minutes for IV PCA. Thirteen extra tasks were identified by the Clinical Trial panel to be associated only with IV PCA, and these eliminated steps primarily explained the estimated total nursing time difference between IV PCA and fentanyl ITS. According to the two Delphi panels, the perceived nursing time consumed was less and the number of tasks was lower for fentanyl ITS than for IV PCA. This benefit associated with fentanyl ITS may lead to other positive outcomes, such as improved nurse satisfaction and improved patient outcomes.

Fentanyl iontophoretic transdermal system for acute-pain management after orthopedic surgery: a comparative study with morphine intravenous patient-controlled analgesia

BACKGROUND AND OBJECTIVES

The fentanyl HCl iontophoretic transdermal system (ITS) has been demonstrated in clinical trials to be safe and effective for acute-pain management after several types of major surgery. The current study compared the efficacy, safety, and convenience of fentanyl ITS with morphine intravenous patient-controlled analgesia (IV PCA) for acute-pain management after unilateral total-hip replacement (THR).

METHODS

In this multicenter (52 sites), randomized, open-label, active-controlled, phase IIIb study, patients (n = 799) received fentanyl ITS (40 mug fentanyl [10-minute infusion/lockout], up to 6 doses/h) or morphine IV PCA (1-mg morphine bolus [5-minute lockout], up to 10 mg/h) after unilateral THR. The primary efficacy measure was success ratings ("excellent" or "good") on the patient global assessment (PGA) of the method of pain control in the first 24 hours. Pain intensity and adverse events were also assessed.

RESULTS

The PGA success ratings (83.0% v 82.2%; difference = 0.9%; 95% CI: -4.4% to 6.1%) and the mean last pain-intensity scores (3.0 v 3.0; difference = 0.0; 95% CI: -0.33 to 0.33) in the first 24 hours were statistically equivalent between fentanyl ITS and morphine IV PCA groups, respectively. The incidence of adverse events was similar between the groups.

CONCLUSIONS

Results of this study demonstrate fentanyl ITS and a standard regimen of morphine IV PCA were comparable methods of pain control for management of acute postoperative pain after THR, on the basis of the PGA success ratings and pain intensity in the first 24 hours of treatment.