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Biomedical subjects

D A Rocke

Publications and source records attributed to D A Rocke.

At least 37 records · Page 2Linked to original sources
PubMed1993

Intubating conditions and haemodynamic changes following thiopentone or propofol for early tracheal intubation.

Intubating conditions and haemodynamic changes were studied 30 sec after a fixed induction dose of thiopentone or propofol in patients scheduled for elective surgery. The hypnotic agent was preceded by the administration of papaveretum 10 mg three minutes before induction and alcuronium 0.2 mg.kg-1 at induction. Ease of intubation was graded and the study conducted in a randomised double-blind fashion. In the thiopentone group (n = 30) intubation was very easy in 73% compared with 79% in the propofol group (n = 29). In two patients in the propofol group the tracheas were moderately difficult to intubate but there were no failed intubations in either group. No patients recalled the intubation period on subsequent postoperative questioning. The immediate post-induction average systolic pressure in the thiopentone group decreased by 0.7% (range 15.9% increase to 25.3% decrease) whilst the post-intubation systolic pressure increased by 6.3% (range - 31.5% increase to 24.2% decrease). In the propofol group there was a decrease in systolic pressure after induction (average 14.4%; range 15.5% increase to 41.4% decrease, P < 0.05) but the subsequent pressor response to intubation was markedly attenuated compared with baseline (average systolic pressure decreased 15.5% (range 22.4% increase to 42.7% decrease)). Following intubation and maintenance, ventilation with nitrous oxide 70% and halothane 1% the systolic pressure decreased markedly in both groups with a greater reduction in the propofol group (P < 0.05). Compared with baseline there were increases (P < 0.0001) in heart rate in both groups from induction of anaesthesia to the end of study.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1993

A reevaluation of the role of crystalloid preload in the prevention of hypotension associated with spinal anesthesia for elective cesarean section.

BACKGROUND: Hypotension after spinal anesthesia for cesarean section remains a common and serious complication despite the use of uterine displacement and volume preloading. The current study revaluated the role of crystalloid volume preloading in this context. METHODS: In a two-stage open sequential design, patients presenting for elective repeat cesarean section were allocated to receive either no preload or 20 ml/kg crystalloid administered over 15-20 min before spinal anesthesia. Hypotension was defined as a decrease in systolic pressure to less than 100 mmHg and to less than 80% of baseline value, and the study was designed to detect a 20% difference in the incidence of hypotension between the groups, with statistical significance at the 10% (alpha = 0.1) level, one-tailed. RESULTS: One hundred forty patients were studied. Hypotension occurred in 43 (55%, 95% CI 43.4-66.4) preloaded and 44 (71%, 95% CI 58-81.8) unpreloaded subjects, a difference in incidence of 16% (95% CI 0.04-31.6), which was statistically significant. There were no significant differences in the severity, timing, or duration of hypotension; the dose requirement for ephedrine; or the clinical and biochemical status of neonates between the groups. The only difference seen was a lower mean base excess (-3.4, SD 2.81 mM-1) in the neonates of hypotensive mothers compared to neonates of nonhypotensive mothers (-2.4, SD 1.99 mM-1). CONCLUSIONS: The study confirms that hypotension associated with spinal anesthesia for cesarean section cannot be eliminated by volume preloading in the supine wedged patient. The relatively small reduction in incidence of hypotension challenges our perception of the value of crystalloid preload. Though volume preload in the elective cesarean section is advocated, the requirement for a mandatory administration of a fixed volume before spinal anesthesia for urgent cases has been abandoned.

Adult↗
PubMed1993

Leg elevation and wrapping in the prevention of hypotension following spinal anaesthesia for elective caesarean section.

Ninety-seven parturients undergoing elective Caesarean section were allocated randomly to have their legs elevated to approximately 30 degrees on pillows or elevated and wrapped with elasticated Esmarch bandages or neither (controls) following spinal anaesthesia. All patients received intravenous crystalloid (20 ml.kg-1 over 20 min) prior to spinal injection and were placed in the left lateral tilt position. Significant hypotension was treated with intravenous ephedrine in 5 mg bolus doses. Leg wrapping resulted in a significant reduction in the incidence of postspinal hypotension in comparison to the control group (18% compared to 53%, p = 0.004). This represents a five-fold reduction in the likelihood of postspinal hypotension (odds ratio 5.3, 95% CI 1.7-16.3). Leg elevation alone did not significantly reduce the incidence of hypotension (39%). There was no significant difference in the time of onset of hypotension between the groups. For those patients requiring ephedrine, there was no significant difference in mean dose requirements between the groups. The use of leg compression immediately postspinal provides a simple means of reducing the accompanying hypotension and should be used more widely.

Adult↗
PubMed1993

Intravenous ranitidine reduces the risk of acid aspiration of gastric contents at emergency cesarean section.

This study documented gastric pH and volume and the number of patients at risk of acid aspiration of gastric contents in a group of mothers undergoing emergency cesarean section under general anesthesia. Patients were randomized in a double-blind fashion to receive ranitidine, 50 mg intravenously, or placebo at the time of decision to proceed to cesarean section. In addition, all patients received 30 mL of 0.3 M sodium citrate on entry into the operating room. Aspiration of gastric contents was undertaken immediately after endotracheal intubation (PI) and before tracheal extubation. Patients with both pH < 3.5 and volume > 25 mL were deemed to be at risk of acid aspiration should regurgitation occur. Postintubation, 12 patients (4%) were at risk in the citrate-alone group and 7 patients (2.3%) were at risk in the ranitidine/citrate group (not significant). Preextubation, 17 patients (5.6%) were at risk in the citrate-alone group and 1 patient (0.3%) was at risk in the ranitidine/citrate group (P < 0.05). PI pH in patients receiving ranitidine/citrate (mean 5.2, SD 0.8) was significantly higher than in patients receiving citrate alone (mean 4.9, SD 1.1). None of the patients who received ranitidine more than 30 min before the PI sample were at risk compared to 6 (3.2%) in the citrate alone group (P = 0.05). We conclude that 50 mg of intravenous ranitidine given at the time of decision to proceed to cesarean section reduces the risk of acid aspiration provided that at least 30 min have elapsed from injection to induction of anesthesia.

Adult↗
PubMed1993

The labour ward analgesic service at King Edward VIII Hospital, Durban.

The provision of analgesic services to the labour ward at King Edward VIII Hospital was studied during a 1-week period. Of 249 patients, 113 (45%) received no analgesia whatsoever. Intramuscular pethidine was the commonest form of analgesia and was used in 97 patients (39%). Thirty-six patients (14%) received epidural analgesia and only 4 inhalational analgesia using nitrous oxide and oxygen (Entonox). A significant proportion of patients who received pethidine were given the drug between 1 and 3 hours before delivery, increasing the potential for opiate-related neonatal depression. Of the patients given opiate analgesia, 22 (23%) proceeded to caesarean section and could have been at increased risk of aspiration of gastric contents owing to delayed gastric emptying caused by the opiate. One hundred and eleven mothers (76%) who had an obstetric indication for epidural analgesia were denied it because of lack of medical staffing.

Adolescent↗
PubMed1992

Standards of practice in anaesthesia--intra-operative monitoring.

Intra-operative monitoring practice during anaesthesia was studied in a randomised selection of hospitals in different categories. Questionnaires from 45 anaesthetists in 20 hospitals provided information on 973 cases. The study showed that in 11% of cases the patient was left at some stage during anaesthesia without the attention of a medical practitioner and that in 7% of cases no record was made of the anaesthetic or of the parameters monitored. Types of monitoring varied considerably between hospitals and often fell short of acceptable minimal standards. Pulse oximetry, which is considered essential, was used in only 53% of cases. One in 18 cases was associated with a peri-operative critical incident and in 7 cases a critical incident occurred where the monitoring was deemed to be inadequate. Pulse oximetry would have assisted the anaesthetist in 6 of these 7 cases. In 3% of cases the anaesthetist admitted to fatigue during the procedure. This study highlights deficits in anaesthetic practice and in available equipment, both of which require urgent attention.

Anesthesia↗
PubMed1992

Early tracheal intubation with thiopentone in elective surgery.

We have studied tracheal intubating conditions within 30 s of administration of thiopentone in 24 patients and compared this with our usual method of tracheal intubation, which involves 3 min of manual ventilation in 29 patients. All patients received papaveretum 10 mg 3 min before induction and alcuronium at induction of anaesthesia. Satisfactory intubating conditions were observed in 83% of patients in both groups. There were no difficult or failed intubations and no patient had laryngospasm. The duration of laryngoscopy in the control group was 14.1 (SD 8.6) s (range 7-50 s), compared with 12.4 (3.1) s (range 6-20 s), in the early intubation group (ns). In the control group there was a significant decrease in systolic pressure before tracheal intubation and a significant increase in heart rate after intubation, compared with baseline values. The average systolic pressure in the early intubation group increased only minimally: from a pre-intubation value of 143.3 (21.2) mm Hg to 145.5 (25.1) mm Hg after intubation. Our results demonstrate that early tracheal intubation under thiopentone supplemented with an opioid and a non-depolarizing neuromuscular block is feasible, associated with minimal changes in arterial pressure and not accompanied by an increased incidence of side effects.

Adult↗
PubMed1992

Rapid administration of crystalloid preload does not decrease the incidence of hypotension after spinal anaesthesia for elective caesarean section.

Twenty parturients undergoing elective Caesarean section were allocated randomly to receive crystalloid preload 20 ml kg-1 over either 20 min or 10 min before spinal anaesthesia. Significant hypotension (systolic arterial pressure less than 100 mm Hg and less than 80% of baseline value) occurred in six of the 10 patients in the 20-min preload group and seven of 10 patients in the 10-min preload group (ns). Both groups had a significant (P less than 0.05) increase in central venous pressure during the preload period. The mean central venous pressure in the 10-min group was 11.9 mm Hg (range 6-19 mm Hg), which was significantly greater (P less than 0.05) than that in the 20-min group (mean 7.3 mm Hg, range 2-13 mm Hg). Three patients in the 10-min group had clinically unacceptable increases in central venous pressure. This study has demonstrated that rapid administration of crystalloid preload before spinal anaesthesia did not decrease the incidence or severity of hypotension, and questions the role of crystalloid preload.

Adult↗
PubMed1992

Thrombelastography after aspirin ingestion in pregnant and non-pregnant subjects.

The thrombelastograph (TEG) and bleeding time were performed before and 6 h after a single oral dose of aspirin 600 mg in a group of eight healthy volunteers and 12 pregnant patients. Measured TEG variables (r, k, r+k times and maximum amplitude) were unaltered after aspirin although there was a significant prolongation of the bleeding time in both groups. Although the TEG appeared not to detect aspirin-induced changes in platelet function, the TEG measures all phases of coagulation and the unaltered TEG after aspirin suggested a functioning coagulation system.

Aspirin↗
PubMed1992

Relative risk analysis of factors associated with difficult intubation in obstetric anesthesia.

Difficult tracheal intubation, often unexpected, has been identified as the commonest contributory factor to anesthetic-related maternal death. The ability to predict such cases preoperatively would be of great value. Preoperative airway assessment and potential risk factors for difficult tracheal intubation were recorded in 1,500 patients undergoing emergency and elective cesarean section under general anesthesia. Airway assessment using a modified Mallampati test recorded oropharyngeal structures visible upon maximal mouth opening. Potential risk factors documented were obesity; short neck; missing, protruding, or single maxillary incisors; receding mandible; facial edema; and swollen tongue. Subsequent to induction of anesthesia, the view at laryngoscopy and difficulty at intubation were graded. There was a significant (P less than 0.001) correlation between the oropharyngeal structures seen and both the veiw at laryngoscopy and difficulty at intubation. Univariate analysis demonstrated a significant association between difficult intubation and short neck (P less than 0.001), obesity (P less than 0.0001), missing maxillary incisors (P less than 0.02), protruding maxillary incisors (P less than 0.001), single maxillary incisor (P less than 0.0001), and receding mandible (P less than 0.003). Neither facial edema (P = 0.414) nor swollen tongue (P = 0.141) were found to be associated with difficult intubation. Multivariate analysis removed obesity and missing and single maxillary incisors as risk factors. Obesity was eliminated because of its strong association with short neck. The probability of experiencing a difficult intubation for various combinations of risk factors was determined.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Prophylactic intramuscular ephedrine prior to caesarean section.

Thirty healthy parturients, having given informed consent, were randomly allocated in a double-blind study to receive an intramuscular injection of either 0.9% sodium chloride (control), ephedrine 25 mg, or ephedrine 50 mg, 30 minutes prior to general anaesthesia for caesarean section. Nine patients (90%) in the 50 mg group and five patients (50%) in the 25 mg group demonstrated reactive hypertension of 20% or greater from control. The mean maximum increase in the 50 mg group was 28.2% (range 4.4-38.3%). Maternal pH was significantly lower (P = 0.03) in the ephedrine 50 mg group. Neonatal acid base status was significantly impaired in the ephedrine 50 mg group with umbilical venous pH (P = 0.0001) and umbilical arterial pH (P = 0.001) being significantly lower than the control group. The associated increase in umbilical arterial base deficit suggests a metabolic component due to fetal asphyxia related to decreased uterine blood flow. We conclude that the prophylactic administration of intramuscular ephedrine prior to spinal anaesthesia is associated with an unacceptably high incidence of maternal hypertension, and should the spinal fail and general anaesthesia be required, also results in adverse neonatal biochemical changes. The technique is therefore not to be recommended.

Adult↗