Sternocleoidomastoid muscle length predicts depth of central venous catheter insertion

BACKGROUND

Correct central venous catheter (CVC) insertion avoids serious complications, especially fatal intracardiac impalement. There are only few methods which discussed the depth of CVC insertion previously. Predicting the depth of CVC by body surface landmark is an easy and quick way, which is applied most wildly. Chest X-ray is a standard procedure to examine the depth of CVC. However, chest X-ray is not routinely availale, especially in emergency situations. Recent publications demonstrated that the determination of accurate placement by chest X-ray can be substituted by ECG guidance. We would like to find the correlation between surface anatomic landmarks and the depth of CVC insertion, and a method that could be applied easily and quickly to predict the depth of CVC insertion through ECG guidance.

METHODS

Thirty patients receiving orthopedic, neurologic and gastrointestinal operations under general anesthesia were chosen for the study of CVC insertion via the right internal jugular vein puncture. The puncture site is at the mid-point of sternocleidomastoid (SCM) muscle, and direction of puncture is 30-45 degrees, pointing to nipple. ECG guidance is applied for the depth of CVC measurement. Body height, sitting height, length of sternum and SCM muscle were measured for reference.

RESULTS

Both the length of SCM muscle and body height have statistically meaning for predicting the depth of CVC insertion (P < 0.001 vs. P = 0.012). In point of accuracy, SCM muscle length might be more significant in view of yielding a smaller P-value. And, the depth of CVC is equal to half of the length of SCM muscle plus 6.5 cm in adults aged 18 to 78 yrs.

Dexamethasone effectively reduces postoperative nausea and vomiting in a general surgical adult patient population

BACKGROUND

Postoperative nausea and vomiting (PONV) is still a common and major complication for surgical patients, which may delay post-anesthetic care unit discharge, prolong hospital stay and thus increase the cost of hospitalization. It is understood that PONV is a multi-factorial outcome and occurs more often with general anesthesia than with other anesthetic methods. Prophylactic administration of antihistamines, antidopaminergics, anticholinergics, phenothiazines, serotonin antagonist, steroids and even acupuncture has been shown to be effective. However, expenses and side effects of these agents have also been a concern for clinical doctors. The aim for this prospective study was to find an agent that is cost effective and side effect free (or at least with a low incidence of side effects) for the prevention of PONV.

METHODS

A total of 700 adult surgical patients who planned to have surgery under general anesthesia were enrolled in this double-blinded, randomized and placebo-controlled study. Group P received the placebo (0.9% normal saline 2 ml) and Group D received 10 mg dexamethasone intravenously right before the induction of anesthesia.

RESULTS

We found that during the postoperative period of 1-8 h, patients in Group D reported a lower incidence of PONV (24%) than those in Group P (39%, p < 0.001). Patients in Group D also requested less rescue anti-emetic (17%) than those in Group P (30%, p < 0.05). The same phenomenon was also noted in the 8-to-24-hour interval (PONV 4% vs. 12%, p < 0.05 and rescue anti-emetic 3% vs. 9%, p < 0.05 in Group D vs. Group P, respectively.)

CONCLUSIONS

We conclude that the prophylactic intravenous administration of 10 mg dexamethasone immediately before the induction of anesthesia is effective in preventing PONV in the general surgical adult patient population.

Propofol inhibits neuronal firing activities in the caudal ventrolateral medulla

BACKGROUND

Propofol is a potent intravenous anesthetic. The action of propofol on the medullary depressor area, the caudal ventrolateral medulla (CVLM), has not been well established. We therefore performed extracellular recordings to study the neuronal activity of the CVLM in cats before and after intravenous propofol administration, to investigate its influence on neuronal firings.

METHODS

Experiments were performed on 31 cats anaesthetized with a mixture of alpha-chloralose and urethane administered intraperitoneally. Mean systemic arterial pressure, heart rate, and the neuronal firing (NF) rate were continuously recorded before and after intravenous injection of a single dose of 2 mg x kg(-1) propofol or separate supplemental doses of 1, 2, and 4 mg x kg(-1) propofol until those parameters had returned to the premedication level.

RESULTS

Propofol dose-dependently and reversibly inhibited the NF rate after the supplemental doses of 1, 2, and 4 mg x kg(-1) propofol. The control NF rate of 17.9 +/- 8.6 Hz was depressed to 15.8 +/- 8.5 Hz after the first dose of propofol (p < 0.05 vs. the control), and was further depressed to 12.8 +/- 8.3 Hz (p < 0.05 vs. the control) and 10.0 +/- 7.9 Hz (p < 0.05 vs. the control) after the second and the third doses of propofol, respectively.

CONCLUSION

The dose-dependent inhibition of the spontaneous neuronal firing rate is the main pharmacological action of propofol in the caudal ventrolateral medulla of cats.

Dansyl-PQRamide, a possible neuropeptide FF receptor antagonist, induces conditioned place preference

Neuropeptide FF (NPFF) is an endogenous anti-opioid peptide. NPFF could potentiate the naloxone-precipitated morphine withdrawal syndromes in morphine-dependent rats, indicating the possible involvement of the endogenous NPFF system in opioid analgesia and dependence. The present study was performed to examine the effects of dansyl-PQRamide (dns-PQRa), a putative NPFF antagonist, on conditioned place preference (CPP), in addition, its interaction with the opioid system. Two CPP experiments were conducted. First, rats were treated with dns-PQRa (4-13 mg/kg, i.p.) and paired with the non-preferred compartment while the vehicle was paired with the preferred compartment. Second, similar to experiment 1 except naloxone (1 mg/kg, i.p.) was given 10 min prior to each dns-PQRa administration. The post-drug place preference was examined after 4 alternative pairings. Another group of animals after repetitive dns-PQRa treatments were analyzed for levels of neurotransmitters in discrete brain areas. Dns-PQRa (4-13 mg/kg, i.p.) induced a significant dose-dependent CPP. The dns-PQRa-induced CPP was completely blocked by pretreatment with 1 mg/kg i.p. naloxone, while naloxone alone did not induce any place aversion. The chronic dns-PQRa-treated (13 mg/kg, i.p., b.i.d.) rats caused a significant increase in 3,4-dihydroxyphenylacetic acid and 5-hydroxyindoleacetic acid in the olfactory tubercle compared to the vehicle-treated controls. There was also an increase in the turnover of serotonin in the olfactory tubercle, nucleus accumbens and medial prefrontal cortex. These results suggest that blockade of the NPFF system produces rewarding, possibly via an inhibition of the anti-opioid action of NPFF. These results also reveal a close relationship between NPFF, drug rewarding and the dopaminergic and serotoninergic neurons in the mesolimbic system.