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Biomedical subjects

R J Harwood

Publications and source records attributed to R J Harwood.

17 recordsLinked to original sources
PubMed2002

Training course in local anaesthesia of the airway and fibreoptic intubation using course delegates as subjects.

BACKGROUND: We describe a practical method of training anaesthetists in the technique of awake fibreoptic intubation. This is performed on a training course using the delegates as subjects. METHODS: The first 15 subjects underwent cardiovascular monitoring during airway fibreoptic endoscopy performed by other course members. They were subsequently interrogated by use of a questionnaire. RESULTS: Evidence from questionnaires suggests this method of instruction is acceptable in this self-selected group of individuals. Gagging was the commonest unpleasant side-effect of airway endoscopy, although only one delegate rated this as uncomfortable. Fifty-four per cent of subjects found the procedure slightly painful; 46% reported no pain at all. Overall, the procedure was rated as acceptable by 85% of subjects and enjoyable by 15% of subjects. No delegate found endoscopy or intubation distressing. Cardiovascular monitoring revealed pulse rate and arterial pressure changes of less than 25% of baseline values. Paraesthesia developed in one individual and nasal bleeding in two cases, neither of which was clinically significant and did not interfere with endoscopy. CONCLUSIONS: The use of course delegates as subjects for training was acceptable to anaesthetists and is associated with a low level of discomfort and morbidity.

Adult↗
PubMed1996

Intrathecal administration of morphine for elective Caesarean section. A comparison between 0.1 mg and 0.2 mg.

This study compared the quality of analgesia and incidence of adverse effects with two doses of intrathecal morphine in patients undergoing elective Caesarean section. Fifty patients were randomly allocated to receive either morphine 0.1 mg or 0.2 mg in addition to a standard intrathecal dose of 2.5 ml bupivacaine 0.5% in 8% dextrose. The quality of analgesia was assessed using visual analogue scores and the incidence of nausea, vomiting and itching were recorded during the first 24 h postoperatively. There was no statistically significant difference in the quality of analgesia nor in the incidence and severity of itching between the two groups. Fewer patients in the 0.1 mg morphine group experienced postoperative nausea and vomiting (7 versus 14, p < 0.05). We conclude that the use of 0.1 mg morphine intrathecally produces comparable analgesia to 0.2 mg after Caesarean section with significantly less nausea and vomiting.

Analgesia, Obstetrical↗
PubMed1995

Effect of demand frequency on lockout period. The Abbott Provider 5500 Patient-Controlled Analgesia machine.

An Abbott Provider 5500 Patient Controlled Analgesia machine was noticed to have developed a prolonged lockout period when frequent analgesic demands were being made. This study tested five other machines and demonstrated that the duration of the lockout period was influenced by the frequency of analgesic demands. This finding could have clinical implications and we recommend that the duration of the lockout period should be specifically examined during the testing of patient-controlled machines.

Analgesia, Patient-Controlled↗
PubMed1995

The effect of different end-tidal volatile agent and carbon dioxide concentrations upon the incidence of postoperative shivering.

Sixty patients (47 female) undergoing surgical excision of three or more wisdom teeth were randomly allocated into three groups with differing end-tidal carbon dioxide and volatile agent concentrations during maintenance of anaesthesia. The anaesthetic techniques employed were identical in all other respects. All patients were observed for 10 min after arrival in the recovery area to assess the presence and severity of shivering, axillary temperature and oxygen saturation. There were no significant differences in axillary temperatures between groups or between shivering and non-shivering patients, although there was a significant difference (p = 0.001) in duration of anaesthesia between shivering and non-shivering patients. There was no significant difference between groups with respect to the incidence of shivering (p = 0.96).

Adult↗
PubMed1993

Endotoxin-induced organ injury.

OBJECTIVE: To review the effects of endotoxemia on the major organ systems of the body and discuss potential mechanisms of tissue injury. DESIGN: Appraisal of 60 articles representing a cross section of studies relating to in vivo and in vitro responses to endotoxin. MAIN METHODS: Cell cultures, isolated tissue preparations, animal and human studies. RESULTS: Endotoxemia results in the activation of numerous cellular and hematogenous mediators. These mediators range from prostaglandins, thromboxanes, and leukotrienes, to complement components. Tumor necrosis factor may be responsible for initiating many of the observed responses to endotoxin. Species and tissue specificity are a prominent feature of the response to endotoxin. CONCLUSIONS: No single agent can yet be implicated as the common mediator of endotoxin-induced organ injury. Endotoxin initiates the elaboration of a cascade of secondary mediators that amplify the response to the initial insult. The relative importance of individual agents as mediators of the response to endotoxin varies with the experimental model studied.

Animals↗
PubMed1992

Learning during general anaesthesia: implicit recall after methohexitone or propofol infusion.

Forty-four patients undergoing coronary artery surgery were allocated randomly to receive an infusion of propofol or methohexitone as a hypnotic supplement to a fentanyl-based anaesthetic technique. A taped message was played to the patients, consisting of 10 words associated with prompt sentences and a suggestion for a specific postoperative behavioural response. Twenty patients (10 propofol and 10 methohexitone) (perioperative group) were exposed to the taped message during surgery and in the immediate postoperative period and the other 24 patients (postoperative group) were exposed to the tape only in the postoperative period, after return to the intensive care unit (ICU). No patient had explicit recall of any events during the period when the tape was played. The patients in the propofol group who heard the tape during surgery had significant implicit recall of the word associations compared with the equivalent 10 methohexitone patients (P = 0.004), when tested 48 h after surgery. The patients who were played the tape whilst receiving identical infusion regimens for sedation in the ICU did not demonstrate implicit recall of the word associations in either the propofol or the methohexitone groups. There was no evidence of a response to the specific behavioural suggestion during the postoperative interview. The results confirm that auditory perception can occur during clinically adequate anaesthesia, and that suppression of auditory awareness or learning is a function of both the pharmacological degree of sedation and the degree of surgical stimulation.

Anesthesia, General↗
PubMed1992

Evaluation of a reservoir device for metered-dose bronchodilator delivery to intubated adults. An in vitro study.

UNLABELLED: We investigated the use of a reservoir device for delivery of a MDI bronchodilator aerosol using a lung model of an intubated, mechanically ventilated adult. METHODS: Albuterol (Proventil) was delivered with a MDI using three methods. In method 1, the MDI was attached directly onto the ETT using a commercially available actuator/adapter. In method 2, the Monaghan AeroVent reservoir was placed on the inspiratory limb of the ventilator circuit just before the patient Y connector. In method 3, the AeroVent was placed between the patient Y connector and the ETT. Standardized ventilator settings with a Servo 900C were used for all three methods (VE = 9.6 L; respiratory rate = 12 breaths per minute; TI = 20 percent of 1 s). Aerosol drug delivery was measured at the distal tip of the ETT using a spectrophotometric technique. Percentage of amount delivered was calculated from measured delivery of the MDI. RESULTS: The MDI directly on the ETT delivered 7.3 percent of the total dose to the end of the ETT. The AeroVent on the inspiratory limb increased this to 32.1 percent and the AeroVent between the Y connector and the ETT delivered 29 percent. Both reservoir delivery methods delivered significantly more drug than direct placement of the MDI on the ETT (p less than 0.01) but did not differ from each other (p greater than 0.05). CONCLUSIONS: Use of the AeroVent reservoir chamber significantly increased bronchodilator delivery by aerosol with an MDI in an adult lung model of an intubated patient on ventilatory support.

Adult↗
PubMed1988

Test method for evaluation of loss of prime in metered-dose aerosols.

A new test method is described for assessing the loss of prime in metered-dose aerosols. Two representative metered-dose valve designs and two storage positions were used to assess the utility of this test method at three different sites. Loss of prime, defined as a valve delivery 15% below the mean, was detected in three of the four test configurations. The first significant loss of prime in this study was observed at the two-week time point for valves without drain tanks stored in the upright position. Onset of loss of prime was shown to be dependent on valve design as well as storage position, thus alternate valves or storage conditions should yield different results. This test method appeared to be reproducible over the three test sites, with a slight variation in results attributed to differences in storage conditions and agitation during sample handling. This test method intentionally excluded agitation which is in sharp contrast to the normal "shake well before use" instruction to the patient. Following one priming actuation, all of the valves returned to their mean valve delivery.

Aerosols↗
PubMed1985

Dissolution rate studies of compression-molded units made from hydroxypropyl cellulose films.

Hydroxypropyl cellulose films were prepared by compression molding of three different lots of hydroxypropyl cellulose powder at 149 degrees C, 188 degrees C, and 232 degrees C. Rectangular pieces were cut from these films and viscosity average molecular weight (Mv), degree of orientation, and rate of dissolution were measured. The viscosity average molecular weight (Mv) decreased with increasing processing temperature, while, as expected, the dissolution rate increased. Orientation in the thermoformed units was also evaluated. Correlation of these data with the Mv values suggests that orientation has some controlling influence on the dissolution rate. Because the samples possessing the least orientation were molded at the highest temperature, they also had the lowest Mv due to thermal degradation. Therefore, the effects of molecular weight were not fully separated from orientation effects with regard to control over the dissolution rate.

Cellulose↗