Biomedical subjects
B O'Hare
Publications and source records attributed to B O'Hare.
Child health in Africa: 2005 a year of hope?
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Paediatric near-drowning: mortality and outcome in a temperate climate.
The decision whether to continue to resuscitate the paediatric victim of near-drowning is influenced by potential poor neurological outcome. A low core body temperature at presentation is frequently cited as a reason to continue resuscitation. We report the case of an 11 month old infant admitted to the intensive care unit following near-drowning and a prolonged resuscitation. The infant's core body temperature was 29 degrees C. Cardiac output was restored, but the child remains in a persistent vegetative state. We present the results of a ten year review of near-drowning in a tertiary referral institution, to evaluate the mortality and outcome in a temperate climate. Thirteen patients were identified in the review. The mortality was 23%. The incidence of a persistent vegetative state was 15%. Asystole, immersion time greater than 15 minutes, resuscitation time longer than 30 minutes, the administration of epinephrine, and a low core body temperature were associated with a poor outcome.
Accessibility of intensive care facilities in Ireland to critically ill patients.
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Shoshin beri-beri precipitated by intravenous glucose.
A thiamine deficient patient presented to the emergency department with an acute confusional state, becoming unconscious and hypotensive following the administration of 32 g of intravenous glucose over 4 hr. A dramatic clinical improvement in his cardiovascular and neurological status followed a single intra-venous dose of 250 mg of thiamine. Profound thiamine deficiency was confirmed on biochemical testing. A substantial proportion of hospital patients are thiamine deficient and intravenous dextrose may precipitate cardiovascular collapse and lactic acidosis due to the development of 'shoshin' beriberi. A rapid response to intravenous thiamine may confirm the diagnosis. All patients presenting with acute neurological dysfunction should receive thiamine before glucose-containing solutions are administered.
A case of pneumomediastinum in paediatric ARDS: to oscillate or not?
An 18-month-old was transferred (intubated and ventilated) to our hospital with staphylococcal tracheitis, which progressed to a necrotizing pneumonitis, complicated by surgical emphysema and pneumomediastinum. Maximum conventional ventilation on a Servo 300 failed. Treatment with high frequency oscillatory ventilation (for 10 days) with a permissive hypercarbia and hypoxaemia strategy to limit mean airway pressure facilitated recovery in our patient.
Evaluation of the effects of levobupivacaine on clotting and fibrinolysis using thromboelastography.
Amide local anaesthetics inhibit platelet function. We hypothesized that residual anaesthetic in the epidural space could decrease efficacy of an epidural blood patch in preventing postdural puncture headache. Levobupivacaine has recently been approved for epidural anaesthesia. Its effects on coagulation have not previously been studied. The aim of this study was to determine the effects of levobupivacaine on clotting using thromboelastography. Ten ASA Class I volunteers were studied. Venous blood samples were analysed using a Haemoscope 2000D TEG analyser. Whole blood, a 50% saline control and two levobupivacaine solutions (2.5 mg mL(-1) and 2.5 microg mL(-1) in blood) were compared. The former reproduces that produced in the epidural space by blood (20 mL for an epidural blood patch) and levobupivacaine 0.5% (20 mL). The latter approximates plasma concentrations following epidural injection of levobupivacaine 0.5% (20 mL). P < 0.05 was considered significant. Maximum amplitude (MA), a measure of clot strength, is decreased by levobupivacaine 2.5 mg mL(-1). Levobupivacaine 2.5 mg mL(-1) decreases clot strength and may reduce efficacy of a prophylactic epidural blood patch.
Comparison of exogenous surfactant and positive end-expiratory pressure therapies in a model of human breast milk-induced acute lung injury in rabbits.
To evaluate surfactant and positive end-expiratory pressure (PEEP) as potential therapies for the acute lung injury after tracheal instillation of 0.8 ml kg-1 human breast milk (HBM) acidified to pH 1.8, adult white rabbits were anaesthetized, tracheostomized, ventilated and randomized to (six rabbits per treatment): (i) no treatment after HBM (control); (ii) exogenous Bovine surfactant (100 mg kg-1) 1 h after HBM; (iii) PEEP-pre (0.5 kPa PEEP) before and after HBM; or (iv) PEEP-post (0.5 kPa PEEP) after HBM. A fifth group of six rabbits received no tracheal instillate (no aspirate). The alveolar to arterial oxygen tension gradient (A-aDO2) and dynamic compliance were measured pre-injury and hourly for 4 h. At post-mortem, the lungs were examined histologically. A-aDO2 in all four HBM-injured groups increased to a maximum at 1 h post-injury; A-aDO2 then returned towards the baseline in the surfactant and PEEP-post groups, but remained increased in the PEEP-pre and control groups. Dynamic compliance decreased in all four HBM-injured groups. A-aDO2 and compliance were unchanged in the no aspirate group. Bronchoalveolar architecture after surfactant therapy was normal. We conclude that surfactant is a more effective therapy for HBM-induced lung injury than either 0.5 kPa PEEP-post or PEEP-pre injury.
Hemoptysis and Epstein-Barr virus infection.
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Pharmacokinetic profile of rectally administered diclofenac sodium in children undergoing adenotonsillectomy
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The effects of ropivacaine hydrochloride on coagulation and fibrinolysis. An assessment using thromboelastography.
Amide local anaesthetics impair coagulation by inhibition of platelet function and enhanced fibrinolysis. The potential therefore exists that the presence of amide local anaesthetics in the epidural space could contribute to the therapeutic failure of an epidural autologous blood patch. Ropivacaine is an aminoamide local anaesthetic increasingly used for epidural analgesia and anaesthesia, particularly in obstetric practice. This study was undertaken to investigate whether concentrations of ropivacaine in blood, which could occur clinically in the epidural space, alter coagulation or fibrinolysis. Thromboelastography was used to assess clotting and fibrinolysis of blood to which ropivacaine had been added. Although modest alterations in maximum amplitude, coagulation time and alpha angle were observed, the effect of ropivacaine on clotting and fibrinolysis was not clinically significant. We conclude that it is unlikely that the presence of ropivacaine in the epidural space would reduce the efficacy of an early or prophylactic epidural blood patch.
Acute lung injury after instillation of human breast milk into rabbits' lungs: effects of pH and gastric juice.
BACKGROUND: The authors compared the lung injury in rabbits that occurred after tracheal instillation of human breast milk (HBM) acidified to pH 1.8 with hydrochloric acid (HCl), HBM at its native pH (7.0), and HBM acidified with gastric juice to pH 1.8 and 3.0. METHODS: The alveolar-to-arterial oxygen tension gradient and dynamic compliance were recorded before and hourly for 4 h after intratracheal instillation of 0.8 ml/kg HBM acidified with HCI (pH 1.8), HBM at its native pH (7.0), HBM acidified with gastric juice (pH 1.8 or 3.0), or 5% dextrose solution acidified with gastric juice (pH 1.8) as a control in 30 adult rabbits. The circulating neutrophil count and phagocyte oxidant activity were determined before and 1 and 4 h after instillation. RESULTS: The alveolar-to-arterial oxygen tension gradient increased and dynamic compliance decreased significantly in all groups after instillation of HBM compared with baseline values and those in the control group. The severity of the lung injury after instillation of HBM at all pH values (1.8, 3.0, and 7.0) and after acidification with gastric juice or HCl was similar. The circulating neutrophil count increased steadily for 4 h after instillation (P < 0.013), whereas spontaneous phagocyte oxidant burst activity peaked at 1 h (P < 0.007) and returned to baseline by 4 h after instillation. CONCLUSIONS: The severity of the lung injury after tracheal instillation of 0.8 ml/kg HBM in rabbits is similar at pH values between 1.8 and 7.0 after acidification with HCl or gastric juice. Tracheal instillation of HBM increases the circulating neutrophil count and phagocyte oxidant burst activity.
Intra-ocular pressure changes following laryngeal mask airway insertion: a comparative study.
We compared the effects of the Brain laryngeal mask airway with a tracheal tube on intra-ocular pressure. Propofol was used as induction agent and atracurium as relaxant. Twenty-six patients with normal intra-ocular pressure undergoing cataract surgery were randomly allocated to two groups. Group A (n = 13) had a laryngeal mask airway inserted and Group B (n = 13) had a tracheal tube inserted. Intra-ocular pressure was measured just before insertion of the airway, 20 s after insertion and at 2 min. In the laryngeal mask airway group there were no significant changes in mean intra-ocular pressure. In the tracheal tube group there was a significant rise in mean intra-ocular pressure at 20 s (p = 0.0056) which returned to pre-insertion levels at 2 min. We conclude that the laryngeal mask airway continues to have advantages over the tracheal tube for ophthalmic surgery despite the use of propofol and atracurium as anaesthetic agents.
Acute lung injury after instillation of human breast milk or infant formula into rabbits' lungs.
BACKGROUND: Recent interest in shortening the fasting interval after ingestion of milk products demonstrated large volumes of breast milk in the stomach 2 h after breastfeeding. Although aspiration is a rare event, if it were to occur with human breast milk, it is important to understand the extent of the lung injury that might occur. Therefore, the response to instillation of acidified breast milk and infant formula in the lungs of adult rabbits was studied. METHODS: In 18 anesthetized adult rabbits, 1 of 3 fluids (in a volume of 0.8 ml.kg-1 and pH level of 1.8, acidified with hydrochloric acid); saline, breast milk, or infant formula (SMA, Wyeth, Windsor, Ontario), was instilled into the lungs via a tracheotomy. The lungs were ventilated for 4 h after instillation. Alveolar-to-arterial oxygen gradient and dynamic compliance were measured before and at hourly intervals after instillation. After 4 h, the rabbits were killed and the lungs were excised. Neutrophil infiltration was quantitated by a pathologist blinded to the instilled fluid. A histologic control group of four rabbits was ventilated under study conditions without any intratracheal fluid instillation. RESULTS: Alveolar-to-arterial oxygen gradient increased and dynamic compliance decreased significantly during the 4 h after instillation of both breast milk and infant formula compared with baseline measurements and with saline controls (P < 0.05). The neutrophil counts in the lungs from the saline, breast milk, and formula rabbits were significantly greater than those in the control group. CONCLUSIONS: Instillation of acidified breast milk or infant formula (in a volume of 0.8 ml.kg-1 and pH level of 1.8) into rabbits' lungs induces acute lung injury of similar intensity that lasts at least 4 h.
Persistent low cerebral blood flow velocity following profound hypothermic circulatory arrest in infants.
Acute neurological morbidity following repair of congenital heart disease (CHD) in infancy is well recognized, particularly with the modalities of hypothermic cardiopulmonary bypass (CPB) and profound hypothermic circulatory arrest (PHCA). Reduced O2 delivery (perfusion defect) during rewarming following PHCA has been shown in the operating room. This reduction in cerebral blood flow coincides with disordered cerebral metabolism and oxygen utilisation after PHCA. The objective of this study was to extend the period of investigation of cerebral blood flow velocity (CBFV) behaviour in infants following PHCA to determine if hypoperfusion persisted in the paediatric intensive care unit (PICU). Ten patients undergoing CHD surgery were divided, based on the pump modality employed, into either mild hypothermic CPB or profound hypothermic CPB with circulatory arrest. Following admission to the PICU, sequential recordings of the mean CBFV in the middle cerebral artery, anterior fontanelle pressure, haemodynamic variables, tympanic membrane temperature, haematocrit and PaCO2 were performed. The PHCA group had a consistently reduced CBFV compared with the control group (P < 0.05). The CBFV values at one, two and four hours were 60 +/- 11, 51.8 +/- 11.4 and 52.6 +/- 11.9 respectively in the mild hypothermic CPB group. The CBFV values at one, two and four hours were 26.6 +/- 6.8, 32.6 +/- 10 and 34 +/- 8 respectively in the PHCA group. There was no difference in cerebral perfusion pressure between both groups. Tympanic temperature, haematocrit and PaCO2 did not vary between groups at any interval. This study demonstrates a sustained reduction in the CBFV pattern following PHCA into the postoperative period despite adequate cerebral perfusion pressures. This abnormality correlates with electroencephalographic aberrations documented after PHCA. It supports the concept of a prolonged unreactive cerebrovascular bed which could potentially contribute to the acute neurological morbidity following PHCA in neonates.
Clinical audit in intensive care--the Meath Intensive Care Audit.
Audit is now recognised as being an essential component of clinical practice. We report on the first year of the Meath Intensive Care Audit (MICA). This audit was instituted to investigate the activity of the unit, to assess the feasibility of continuous audit in our ICU and to provide data for future development of ICU facilities. Two hundred and fifty four patients were admitted between July 1st 1990 and June 30th 1991. The mean age at admission was 58 years and the mean length of stay 5.2 days. The mean APACHE II score was 16. Thirty four patients (13.4%) died in the ICU and 17 patients died in hospital following discharge from the unit bringing the hospital mortality rate to 20%. The audit proved feasible to implement and data collection is now accepted as a routine part of our ICU work.
Working with small groups. 1. Foreword.
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