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Biomedical subjects

T Frewen

Publications and source records attributed to T Frewen.

8 recordsLinked to original sources
PubMed1991

Acute airway management in the critically ill child requiring transport.

Airway compromise was found to be a common problem in children requiring critical care transport to our hospital. This retrospective review of 39 infants and children was undertaken to assess the frequency and degree of airway compromise in these children, to document the management required and to determine who performed it. Ninety-seven per cent of children had airway difficulties associated with their disease, and one-third of these required further airway management on the arrival of the transport team. Airway specialists had not been involved in the care of these children before the arrival of the transport team. This indicates that greater attention should be paid to airway management as soon as children are identified as being sufficiently ill to require transport to a tertiary care facility.

Anesthesiology↗
PubMed1991

Evaluation of performance characteristics of disposable bag-valve resuscitators.

OBJECTIVE: To evaluate the performance characteristics of disposable bag-valve resuscitators. DESIGN: Single and multitrial tests under simulated clinical conditions. Results of multitrial tests were analyzed by multivariate analysis of variance. SETTING: A pulmonary laboratory in a university hospital. METHODS: We evaluated eight DRs to determine: a) physical characteristics, including the potential for misassembly; b) FIO2 of 1.0 and flow rates of 10 L; c) tidal volume (VT) (male and female operators) using one and two hands; and d) cycling rates at 5 degrees, 20 degrees, and 48 degrees C. RESULTS: All resuscitators met the minimum requirements of the Canadian Standards Association and the American Society for Testing and Materials. However, the CPR and LSP could be assembled incorrectly for use. Three units (B Sav, Pulm, and MPR) delivered significantly less than 80% oxygen (overall p less than .05). Significant increases were seen in VT using two hands vs. one hand (1176 vs. 960 mL, p less than .001) and males vs. females using two hands (1284 vs. 1102 mL, p less than .02). One unit (B Sav) could only be used with two hands. The maximum cycling rates for all units increased significantly (p less than .05) with an increase in temperature from -5 degrees to 20 degrees to 40 degrees C. However, two units (Bag E and MPR) failed to deliver 20 breaths/min at -5 degrees C, while the B Sav and Pulm valves became dysfunctional at 48 degrees C. CONCLUSIONS: While these DRs meet the minimum standards, they should be chosen carefully and evaluated before application in the clinical environment.

Disposable Equipment↗
PubMed1991

Physiological responses to endotracheal and oral suctioning in paediatric patients: the influence of endotracheal tube sizes and suction pressures.

OBJECTIVE: To study the influence of varying outer suction catheter (SC) diameter (OD) to inner endotracheal tube (ETT) diameter (ID) and suction pressures (SP) on heart rate (HR), respiratory rate (RR), mean arterial pressure (MAP), arterial oxygen saturation (SaO 2) and intracranial pressure (ICP) during ETT and oral suctioning. An additional aim was to define an optimal suction catheter size that would prove easy to introduce and be rapidly effective in clearing secretions with the least physiological alteration. DESIGN: Prospective study. SETTING: Paediatric intensive care unit. PATIENTS: Ventilated paediatric patients. INTERVENTION: Patients had ETT suctioning performed in a random fashion using suction catheters with SC outer diameter to inner ETT diameter of approximately 0.4, 0.7 and 0.9 using varying pressures (80, 100, 120 mmHg). Using the medium size suction catheter (OD/ID = 0.7) at 100 mmHg of suction pressure, oral suctioning was compared to ETT suctioning. MEASUREMENTS AND MAIN RESULTS: Seventeen patients were studied (age 6.5 + 5 months). All suction catheters at varying pressures resulted in similar transient alterations in HR, RR, MAP, SaO 2 and ICP following ETT suctioning. Significant changes were seen in SaO 2, HR and ICP, irrespective of the catheter diameter or suction pressure. Oral suctioning resulted in similar trends and magnitude of changes as for ETT suctioning in MAP, RR, HR, and ICP, but less change occurred in the SaO 2 (p less than 0.05). The catheters with OD/ID of 0.7 were easiest to introduce and most effective in clearing secretions. CONCLUSION: Our study suggests that: 1. Tracheal toilet using variations in OD/ID ratios and SP within limits tested resulted in similar significant adverse changes in HR, ICP and SaO 2 and similar trends in RR and MAP. 2. Based on the ease of introduction and the effectiveness of clearing secretions, a medium SC (OD/ID = 0.7) is most appropriate for infants and children. 3. Oral suctioning also results in adverse physiological changes, therefore similar precautions to those taken during tracheal suctioning should be followed for oral suctioning.

Blood Pressure↗
PubMed1990

Prototype volume-controlled resuscitator for neonates and infants.

Twenty-five infants receiving assisted ventilation in an ICU were manually ventilated for 5-min periods using either a new prototype volume-controlled resuscitator (VCR) or a standard self-inflating resuscitator (SIR). Variables monitored during these 5-min periods included heart rate, respiratory rate, mean arterial pressure, mean airway pressure (Paw), end-tidal CO2 (PetCO2), pulse oximetry oxygen saturation, PaO2, and PaCO2. Significant differences in posttrial values for the following variables were: a) PetCO2 (31.2 +/- 9.1 vs. 25.6 +/- 8.2 torr, p less than .001); b) PaCO2 (38.0 +/- 4.9 vs. 33.2 +/- 6.7 torr, p less than .01); and c) pH (7.4 +/- 0.6 vs. 7.5 +/- 0.1, p less than .04) at comparable Paw (9.5 +/- 7.6 vs. 8.0 +/- 6.0, NS). Eighty-four percent (21/25) of infants in the VCR group had normal PaCO2 values (35 to 45 torr) while only 44% (11/25) in the SIR group achieved normocarbia (p less than .001). Measurements of the highest (Pmax) and lowest (Pmin) inspiratory pressure (cm H2O) in 15 patients demonstrated marked variation in Pmax with the SIR. Differences in Pmax (SIR minus VCR) were significant (10.8 +/- 3.7, p less than .02) but not in Pmin (0.5 +/- 3.5, NS). Our study demonstrates that ventilation with the VCR resulted in less hyperventilation with minimal pressure variability as compared with the SIR. Further studies in the neonate are warranted.

Equipment Design↗
PubMed1988

Intensive care course following liver transplantation in children.

We report the postoperative intensive care course of 16 children who underwent 18 orthotopic liver transplantation (OLT) procedures in London, Ontario and compare this experience in our developing transplant center with that reported from the Children's Hospital of Pittsburgh. Assisted ventilation was required in all children, with six requiring ventilation for greater than three days. Six children required positive end expiratory pressure (PEEP) therapy and hypertension was common. Physiologic stability index score was initially high in all patients, but fell on subsequent days. Intensive care survival was 100% with 69% long-term survival, which compared favorably with the information from Pittsburgh. Septic complications, despite immunosuppressive therapy were rare, but hypocalcemia and hypomagnesemia were common.

Adolescent↗
PubMed1982

The effects of deep barbiturate coma on multimodality evoked potentials.

The authors report their investigation of the effects of high-dose barbiturates on the multimodality evoked response in 9 cats. After baseline evoked responses were obtained, boluses of pentobarbital were infused intravenously at regular intervals, amounting to cumulative total doses of 9, 18, 27, 45, 63, 123, and 183 mg/kg at respective infusions. This resulted in gradually increasing serum pentobarbital levels, reaching therapeutic coma levels (4 to 5 mg/dl) after the fifth infusion. At this point, the electroencephalogram was flat, and pressor agents were required to maintain cardiovascular stability. Evoked responses were obtained 15 minutes after each infusion. Brain-stem auditory evoked response (BAER) showed little change in wave latencies at therapeutic coma levels of pentobarbital. Further barbiturates resulted in delay of the late components of this response. In the somatosensory evoked responses (SER), early brain-stem components were relatively unaffected by therapeutic coma levels. Late brain-stem components and the initial cortical response showed progressive latency increase. Late cortical (association cortex) waves were abolished at relatively low doses. The central conduction time was relatively unaffected. The late waves of the visual evoked responses (VER) were abolished with low-dose barbiturates (9 mg/kg). A single positive-negative complex persisted despite massive infusions. It is concluded that evoked responses may prove useful in monitoring patients in deep barbiturate coma, but barbiturate effects must be kept in mind.

Animals↗