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C J Nicholson

Publications and source records attributed to C J Nicholson.

6 recordsLinked to original sources
PubMed1989

The effect of pH-adjusted 2-chloroprocaine on the onset of epidural analgesia in pregnant patients in the lying and sitting position during the first stage of labor.

The purpose of this prospective, randomized, double-blind study was to compare the epidural onset time of 2% 2-chloroprocaine with pH-adjusted 2-chloroprocaine administered in either the sitting or supine position in pregnant patients during the first stage of labor. Patients in Groups I and III received the control solution in the sitting and supine position, respectively. Patients in Groups II and IV received the buffered solution in the sitting and supine position, respectively. The pH and pCO2 of the control and buffered solutions differed significantly. The pH and pCO2 of the control and buffered solutions were 4.38 +/- 0.01, 18.4 +/- 2.2 mm Hg and 7.70 +/- 0.04, 114.9 +/- 3.0 mmHg, respectively. A statistically significant reduction in the time of onset of analgesia in the pH-adjusted groups was noted. Groups I and II had onset times of 4 +/- 1.2 and 4.3 +/- 1.0, whereas Groups II and IV had onset times of 2.6 +/- 0.9 and 2.7 +/- 0.6 min., respectively. There were no intergroup differences in the cephalad spread of analgesia or duration of analgesia. Position had no effect on the onset of analgesia at the S2-3 dermatomes nor on the bilateral cephalad spread of the epidural study solutions. Our results indicate that a pregnant patient may be dosed in the lateral supine position without adversely affecting the caudad or cephalad spread of plain or pH-adjusted 2% 2-chloroprocaine, which is clinically important because the incidence of aortocaval compression is increased in the supine position when compared with the lateral supine position.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1989

The effect of pH and PCO2 on epidural analgesia with 2% 2-chloroprocaine.

Increasing the pH of local anesthetics with sodium bicarbonate has been reported to hasten their onset of action. The purpose of this study was to compare the onset and duration of epidural analgesia with the use of sodium bicarbonate and tromethamine to increase the pH of 2% chloroprocaine (2CP). Five groups of patients were studied: Group I received 2CP; Group II received 2CP buffered to a pH of 7.1 with tromethamine; Group III received 2CP buffered to a pH of 7.1 with sodium bicarbonate; Group IV received 2CP buffered to a pH of 7.7 with tromethamine; and Group V received 2CP buffered to a pH of 7.7 with sodium bicarbonate. The final pH and PCO2 of each solution were measured. Time to onset of analgesia was significantly delayed with either of the tromethamine buffered groups (II [5.6 +/- 1.0 minutes] and IV [5.4 +/- 0.4 minutes]) when compared with data from the unbuffered control (I [4.4 +/- 0.1 minutes]) and the sodium bicarbonate buffered (III [4.5 +/- 0.8 minutes] groups and Group V [2.7 +/- 0.9 minutes]). Only when sodium bicarbonate buffer adjusted to pH 7.7 (Group IV) was onset significantly more rapid than the unbuffered 2CP (I) and tromethamine buffered 2CP (II and IV). Multiple regression analysis revealed that onset times were significantly related to both pH and PCO2. The coefficient of determination for this model was 0.5156.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Alkalinization of chloroprocaine for epidural anesthesia: effects of pCO2 at constant pH.

Increasing the pH of 2% chloroprocaine (CP) with sodium bicarbonate to pH 7.7 hastens the onset of epidural analgesia. The purpose of the present study was to determine the effect of pCO2 on the onset of epidural analgesia with CP buffered to a constant pH 7.7. Four groups consisting of ten patients each were studied: C, control, commercial CP (pH 4.35); B, CP buffered with sodium bicarbonate (pH 7.7); T, CP buffered with tromethamine (pH 7.7), and BT, CP buffered with sodium bicarbonate and tromethamine (pH 7.7). All epidural catheters were placed at the L2-3 or L3-4 interspace using a loss-of-resistance technique with air with each patient in a sitting position. The pH and pCO2 of each local anesthetic solution were measured as well as the onset and duration of analgesia. The study groups did not differ with respect to demography or entry characteristics. There were intergroup differences in the pCO2 values of the study solutions as follows: Group 1 (C), 11.8 +/- 1.5 mmHg; 2 (B), 113.0 +/- 1.4 mmHg; 3 (T), 3.0 +/- 0.3 mmHg, and 4 (BT), 74.1 +/- 1.0 mmHg, respectively. The time to the onset of analgesia was significantly faster in Group 2 (B; 2.7 +/- 0.8 minute), while the onset of analgesia was significantly slower for Group 3 (T; 5.4 +/- 0.4 minute) than either Group 1 (C; 4.2 +/- 0.8 minute) or Group 4 (BT; 3.4 +/- 0.3 minute). Regression analysis revealed that the onset times of the buffered solutions were significantly related to pCO2 (r2 = 0.81).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗