Impact of drains on nausea and vomiting after thyroid and parathyroid surgery: a randomized controlled trial.

OBJECTIVE: Nausea and vomiting are common side effects following thyroid and parathyroid surgery. In a prospective controlled randomized trial, postoperative nausea and vomiting (PONV) and the number of episodes of vomiting were defined as two primary endpoints. We analysed whether the placement of drains after thyroid or parathyroid surgery enhances PONV and/or influences vomiting. PATIENTS AND METHODS: From November 2007 to January 2012, 136 consecutive patients were included for thyroid or parathyroid surgery and were randomly assigned to group A (drain, n = 69) or group B (no drain, n = 67). PONV was assessed with visual analogue scale (VAS; range 0 to 10) measurements. Furthermore, episodes of vomiting as well as analgetic and antiemetic therapies were recorded. Difference in neck circumference was compared pre- and postoperatively. RESULTS: Patients' characteristics did not differ between group A and B. Postoperative VAS values for pain were 2.4 ± 0.3 (group A) and 2.6 ± 0.2 (group B) (p = 0.62), and for nausea 1.4 ± 0.2 (group A) and 1.1 ± 0.2 (group B) (p = 0.57). The relative occurrences of episodes for postoperative vomiting were equal in both groups 0.3 ± 0.1 (p = 1.0). Antiemetic drugs were administered 37 times (group A) and 18 times (group B) (p = 0.099). The total number of treatments of patients with antiemetic drugs was 23 (33.3%) in group A vs. 13 (19.4%) in group B (p = 0.081). The neck circumference postoperatively was significantly larger in group B (p = 0.0025). CONCLUSIONS: Drains after surgery do not enhance postoperative pain, nausea and vomiting. The placement of drains in thyroid surgery is recommended to avoid relevant fluid collection. Drains however may influence the amount of antiemetic drug requirements. TRIAL REGISTRATION: CLINICALTRIALS. GOV IDENTIFIER: NCT01679418.

A new double-barrelled, ionophore-based microelectrode for chloride ions.

A new Cl- selective microelectrode based on the ionophore 5,10,15,20-tetraphenyl-21H,23H-porphin manganese(III) chloride is presented which discriminates better against HCO3- and several organic anions than electrodes containing the Corning 477913 ion-exchanger. Using a redesigned construction procedure, fine-tip double-barrelled microelectrodes were produced which had slopes of -52.4 +/- 0.6 mV (SE, n = 24), resistances of about 7.10(11) omega and a selectivity coefficient log KpotCLHCO3 of -1.40 +/- 0.03. Some electrodes showed a small unexplained sensitivity to pH greater than 7.6. When used to puncture cells of isolated S3 segments of rabbit renal proximal tubule during perfusion with HCO3- Ringer solution, the electrodes gave a membrane potential of -69.8 +/- 1.5 mV and an intracellular Cl- activity, [Cl-]i, of 35.3 +/- 2.6 mmol/l. Upon switching bath and lumen perfusions to Cl- -free solutions the "residual" [Cl-]i dropped to 1.20 +/- 0.03 mmol/l, while in similar measurements with ion-exchanger electrodes the "residual" [Cl-]i dropped only to 10.9 +/- 0.5 mmol/l. These observations demonstrate the superiority of the new electrode and prove that previously determined high [Cl-]i values in Cl- -free ambient solutions reflect interference problems rather than non-exchangeable intracellular chloride.

Intracellular magnesium ion selective microelectrode based on a neutral carrier.

A magnesium ion selective microelectrode based on a synthetic neutral carrier is presented. The selectivity of Mg2+ over Na+, K+, H+, and Ca2+ is sufficient for assays of intracellular magnesium ion activities. The microelectrodes with an optimized membrane composition have a resistance of about 5 x 10(10) omega and a 90% response time of less than or equal to 3 s for a tip diameter around 1 microns. The lifetime of the microelectrode cell assembly is longer than 1 week and the emf drift after equilibration is less than or equal to 0.3 mV/h.

NH4+ ion-selective microelectrode based on the antibiotics nonactin/monactin.

A liquid-membrane microelectrode (less than or equal to 1 micron tip diameter) using macrotetrolide antibiotics as ion-selective components is described. The electrode shows selectivities of NH4+ over K+, Na+ and H+ of 3.8, 100 and 150, respectively. The stability and reproducibility of the sensor signal and the response time are determined in solutions with a typical intracellular ion background. The microelectrode does not suffer from significant interference by inorganic and organic inhibitors and lipophilic cations, but high concentrations of lipophilic anions may interfere considerably.

Intracellular neutral carrier-based Ca2+ microelectrode with subnanomolar detection limit.

In intracellular electrolyte solutions a Ca2+-selective microelectrode based on the synthetic electrically neutral carrier N,N,N',N'-tetracyclohexyl-3-oxapentanediamide (ETH 129) shows an improved detection limit when compared with the so far widely used Ca2+ microelectrodes based on the neutral carrier ETH 1001. Detection limits are found at pCa = 9.2 in Ca2+ buffers containing an intracellular background of K+ (125 mM). Selectivity studies in mixed solutions show a preference of Ca2+ over Na+ of 6 X 10(5), over K+ of 1.6 X 10(6), and over Mg2+ of 5 X 10(6). The microelectrode does not suffer from significant interference by inorganic and organic inhibitors and by lipophilic cations and anions. The low detection limit is unchanged at least during the first eight hours of continuous contact with Ca2+ solutions. The EMF drift during the first hour of use is between 5 and 10 mV and is then reduced to about 1 mV/h. The changes in EMF induced between solution of pCa = 7 and pCa = 8 are reproducible within 24.7 +/- 0.4 mV (SD, n = 8, about 3 h). These electrode characteristics were found for single-barrelled microelectrodes of one micrometer diameter front-filled with a PVC-containing membrane phase. In the absence of poly(vinyl chloride) in the membrane phase irregular EMF response curves were obtained throughout. Preliminary punctures of ferret ventricular muscle cells indicate that the Ca2+ electrode response is not disturbed by the contact of a cytosolic milieu.

Design of ionophores for ion-selective microsensors.

Requirements for a reliable use of liquid membrane microelectrodes are discussed in terms of stability, response time, and lifetime on the basis of membrane technological considerations. The selectivity of H+, Li+, Na+, K+, Mg2+, Ca2+, and Cl- microelectrodes is critically evaluated using the Nikolskii-Eisenman formalism. Recent progress in the design of new ionophores is presented. A novel neutral carrier-based Ca2+-selective microelectrode with a detection limit of about 5 X 10(-10) M Ca2+ at a background of 125 mM K+ has been realized. An neutral carrier-based microelectrode for H+ with extended pH range of the sample solution is now available. Promising developments in the field of Li+-, Mg2+-, and Cl--selective ionophores are discussed.