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Gordon B Drummond

Publications and source records attributed to Gordon B Drummond.

8 recordsLinked to original sources
PubMed2006

Effects of short-term isocapnic hyperoxia and hypoxia on cardiovascular function.

Both hypoxia and hyperoxia have major effects on cardiovascular function. However, both states affect ventilation and many previous studies have not controlled CO(2) tension. We investigated whether hemodynamic effects previously attributed to modified O(2) tension were still apparent under isocapnic conditions. In eight healthy men, we studied blood pressure (BP), heart rate (HR), cardiac index (CI), systemic vascular resistance index (SVRI) and arterial stiffness (augmentation index, AI) during 1 h of hyperoxia (mean end-tidal O(2) 79.6 +/- 2.0%) or hypoxia (pulse oximeter oxygen saturation 82.6 +/- 0.3%). Hyperoxia increased SVRI (18.9 +/- 1.9%; P < 0.001) and reduced HR (-10.3 +/- 1.0%; P < 0.001), CI (-10.3 +/- 1.7%; P < 0.001), and stroke index (SI) (-7.3 +/- 1.3%; P < 0.001) but had no effect on AI, whereas hypoxia reduced SVRI (-15.2 +/- 1.2%; P < 0.001) and AI (-10.7 +/- 1.1%; P < 0.001) and increased HR (18.2 +/- 1.2%; P < 0.001), CI (20.2 +/- 1.8%; P < 0.001), and pulse pressure (13.2 +/- 2.3%; P = 0.02). The effects of hyperoxia on CI and SVRI, but not the other hemodynamic effects, persisted for up to 1 h after restoration of air breathing. Although increased oxidative stress has been proposed as a cause of the cardiovascular response to altered oxygenation, we found no significant changes in venous antioxidant or 8-iso-prostaglandin F(2alpha) levels. We conclude that both hyperoxia and hypoxia, when present during isocapnia, cause similar changes in cardiovascular function to those described with poikilocapnic conditions.

Adaptation, Physiological↗
PubMed2003

A capital issue.

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Abbreviations as Topic↗
PubMed2003

Sleep arousal after lower abdominal surgery and relation to recovery from respiratory obstruction.

BACKGROUND: Hypoxemic episodes occur during sleep after abdominal surgery, possibly caused by airway obstruction. The authors found arousals from sleep more often than respiratory disturbances, so they related changes in sleep state (short arousals from sleep and longer periods of wakening) to the sudden increase in respiratory flow that indicates relief from complete or partial respiratory obstruction. METHODS: Sleep state and nasal flow were studied in 16 patients receiving patient-controlled morphine and oxygen by facemask on the night after routine gynecologic surgery. Traces were analyzed separately for sleep events and for sudden increases in respiratory flow. The authors noted sleep events (arousals from sleep and transition from sleep to wake) that occurred within 12 s of relief of obstruction. RESULTS: Sleep quality was poor, with only stage 2 sleep in most patients. Median sleep duration was 70% of the study period, with 15 arousals and 6 awakenings per hour of sleep. Only 30% of arousals and awakenings were associated with relief of obstruction. Relief of obstruction also occurred without arousal from sleep, with a median frequency of 38 (30-62) in each night. Relief of obstruction was more frequently associated with arousal from sleep after benzodiazepine premedication (33% vs. 28%; P = 0.012), but this allocation was not randomized. CONCLUSIONS: Arousals from sleep are frequent after abdominal surgery and mostly not related to respiratory disturbance. Relief of respiratory obstruction can occur during sleep without sleep arousal and during wakefulness.

Abdomen↗
PubMed2002

Endocrine measurements in survivors and non-survivors from critical illness.

OBJECTIVE: To compare measurements of thyroid and adrenal function between survivors and non-survivors in critical illness. DESIGN AND SETTING: Prospective, observational study at the medical/surgical intensive care unit (ICU) at Royal Infirmary of Edinburgh, Scotland. PATIENTS: 163 patients admitted to the intensive care unit over a 4-month period. INTERVENTIONS: We took blood samples within 1 h of ICU admission, and at 08:00 hours on the subsequent 2 days of ICU admission. We measured serum total (TT(4)) and free (fT(4)) thyroxine, total (TT(3)) and free (fT(3)) tri-iodothyronine, thyrotropin (TSH) and plasma cortisol concentrations. MEASUREMENTS AND RESULTS: TT(3) and TT(4) concentrations were significantly less in non-survivors than in survivors on admission and on day 1 but not on day 2. Cortisol concentrations were higher in non-survivors on admission and on day 1 but not on day 2. TSH, fT(3) and fT(4) concentrations did not differ significantly between survivors and non-survivors at any time. Only TT(4) and cortisol were independent predictors of outcome. Prediction of outcome from the admission sample values was not better than using APACHE II scoring. CONCLUSIONS: Thyroid hormone and cortisol concentrations differ between survivors and non-survivors on admission to intensive care, but the values overlap. These differences do not allow accurate prediction of outcome from critical illness.

APACHE↗
PubMed2002

Bispectral index values and spectral edge frequency at different stages of physiologic sleep.

UNLABELLED: Bispectral index (BIS) and spectral edge frequency (SEF) are used as measures of depth of anesthesia and sedation. We tested whether these signals could predict physiologic sleep stages, by taking processed electroencephalogram measurements and recording full polysomnography through a night's sleep in 10 subjects being investigated for mild sleep apnea/hypopnea syndrome. Computerized polysomnograph signals were analyzed manually according to standard criteria, classifying each 30-s epoch as a specific sleep stage. The BIS and SEF values were taken at the end of each period of sleep when the same stage had lasted for at least 2 min. Before sleep, median values for BIS were 97 +/- 12.1 and for SEF 23 +/- 4.2 Hz. After sleep initiation, the median BIS values for arousal, light, slow wave, and rapid eye movement sleep were 67 +/- 20.2, 50 +/- 16.5, 42 +/- 11.2, and 48 +/- 7.1, respectively, and the median SEF values were 20 +/- 4.7, 15 +/- 3.6, 10 +/- 2.6, and 19 +/- 4.1 Hz, respectively. Although both BIS and SEF decreased with increasing sleep depth, the distribution of values at each sleep depth was considerable, with overlap between each sleep stage. Neither BIS nor SEF reliably indicated conventionally determined sleep stages. In addition, the response of the BIS was slow and patients could arouse with low BIS values, which then took some time to increase. IMPLICATIONS: Although computer processing of the electroencephalogram can provide an adequate index of depth of anesthesia, the same processing cannot reliably convey depth of natural sleep. At each sleep stage, the output signal has a wide range of possible values.

Adult↗
PubMed2002

Automatic CPAP compared with conventional treatment for episodic hypoxemia and sleep disturbance after major abdominal surgery.

BACKGROUND: After major surgery, analgesia with opioids can cause obstructive apnea and intermittent hypoxemia, probably from loss of upper airway control. Since this resembles the obstructive sleep apnea syndrome, we tested the possibility that nasal continuous positive airway pressure (nCPAP) would reduce episodes of reduced oxygen saturation and sleep disruption. Because oxygen therapy is frequent after surgery, we also assessed the effect of oxygen on sleep disruption. METHODS: We recruited 48 patients about to have major abdominal surgery. We present data for 34 patients: 27 who received patient-controlled intravenous morphine and 7 who received epidural opioid. Treatment was randomized to either nCPAP or conventional therapy with an oxygen mask. Alternate periods of administration of air and 35% oxygen were used in both groups. If the oxygen saturation as measured by pulse oximetry was consistently <90% on air, the patient was withdrawn from the study. We measured sleep, arousals, oxygenation, episodes of desaturation, and disturbances of respiration. Values are given as median and quartiles. RESULTS: The median proportion of time awake was 65% (45-79%) among control patients and 74% (55-87%) among those undergoing nCPAP. Oxygen administration did not affect the sleep pattern. The median frequency of arousals per hour of sleep was very similar in each group: during air breathing from nCPAP, 125 (76-187), and during air breathing by mask, 116 (84-187). Oxygen therapy had no effect. Oxygenation and hypoxemic events were not improved by nCPAP. Oxygen therapy improved oxygenation and reduced but did not eliminate episodes of desaturation. CONCLUSIONS: Nasal CPAP does not improve sleep and oxygenation or reduce hypoxemic events in the first night after major abdominal surgery.

Abdomen↗