Guidelines for safe transfer of the brain-injured patient: trauma and stroke, 2019: Guidelines from the Association of Anaesthetists and the Neuro Anaesthesia and Critical Care Society.

The location of care for many brain-injured patients has changed since 2012 following the development of major trauma centres. Advances in management of ischaemic stroke have led to the urgent transfer of many more patients. The basis of care has remained largely unchanged, however, with emphasis on maintaining adequate cerebral perfusion as the key to preventing secondary injury. Organisational aspects and training for transfers are highlighted, and we have included an expanded section on paediatric transfers. We have also provided a table with suggested blood pressure parameters for the common types of brain injury but acknowledge that there is little evidence for many of our recommendations. These guidelines remain a mix of evidence-based and consensus-based statements. We have received assistance from many organisations representing clinicians who care for these patients, and we believe our views represent the best of current thinking and opinion. We encourage departments to review their own practice using our suggestions for audit and quality improvement.

The cortisol response to hypobaric hypoxia at rest and post-exercise.

High altitude exposure normally leads to a marked natriuresis and diuresis. Acute mountain sickness is often associated with fluid retention, to which an elevated cortisol may contribute. Most investigators report a rise in resting cortisol with ascent, but little data exist regarding the cortisol response to a day trekking. We therefore measured salivary cortisol during ascent to > 5000 m in a cohort of between 42-45 subjects following a 6-h trek (samples taken between 15:30-16:30 h) and between 15-20 subjects at rest (morning samples taken between 08:00-09:00 h). Morning resting cortisol [nmol/l, mean±sd, (range)] was 5.5±2.9 (2.13-13.61) at 1300 m; 4.7±6.8 (1.4-27.02) at 3400 m, and significantly (p=0.002) rose between 4270 m [3.5±2.1 (1.4-8.34)] and 5150 m [14.5±30.3 (1.9-123.1)]. Post-exercise cortisol [nmol/l, mean±sd, (range)] dropped between 3400 m [7±6 (1.5-33.3)] and 4270 m [4.2±4.8 (1.4-29.5)] (p=0.001) followed by a significant rise in post-exercise cortisol between 4270 m [4.2±4.8 (1.4-29.5)] and 5 150 m [9.2±10.2 (1.4-61.3)] (p<0.001). There were no significant associations between severity of acute mountain sickness and cortisol levels. There was a significant though weak correlation between cortisol post-exercise at 5150 m and oxygen saturation at 5150 m (rho= - 0.451, p=0.004). In conclusion, this is the largest cohort to have their resting and post-exercise cortisol levels ascertained at high altitude. We confirm the previous findings of an elevated resting morning cortisol at > 5000 m, but present the novel finding that the cortisol response to a day trekking at HA appears suppressed at 4270 m.

Cardiovascular physiology at high altitude.

The role of the cardiovascular system is to deliver oxygenated blood to the tissues and remove metabolic effluent. It is clear that this complex system will have to adapt to maintain oxygen deliver in the profound hypoxia of high altitude. The literature on the adaptation of both the systemic and pulmonary circulations to high altitude is reviewed.

Reviewing the needs of forward deployed critical care: South Sudan and the future.

The UK military medical treatment facility (MTF) that deployed to the United Nations Mission in South Sudan in 2017 was based on a facility that can provide damage control surgery and resuscitation for soldiers with ballistic trauma injuries. It had to be supplemented with additional medical equipment and drugs that could support a peacekeeping mission in Africa. The clinicians used this experience and opportunity to review the critical care capability of UK Army Medical Services forward MTFs and recommend changes to reflect the increasing contemporaneous need on recent deployments to support more casualties with medical, infectious diseases and other non-battle injuries and illnesses. A concurrent review of the facility's critical care transfer equipment was also undertaken and allowed it to be adapted for use as either transfer equipment or as a critical care surge capability, to increase the facility's critical care capacity.

Resting and exercising cardiorespiratory variables and acute mountain sickness.

INTRODUCTION: The incidence of Acute Mountain Sickness (AMS) is increasing. In a military context our current operational areas include mountainous regions with the implications of AMS including loss of operational tempo and logistical overstretch. Oxygen saturation and heart rate variability have in some studies been predictive of AMS while in others not. No single factor has been demonstrated consistently to be predictive of developing AMS. METHODS: During an expedition to climb Mt Aconcagua (6959m) we explored the relationship between cardiorespiratory variables and AMS. In 11 subjects we measured simple physiological variables and Lake Louise Score both pre and post a standardised exercise challenge at on arrival at different altitudes and after a period of acclimatization. RESULTS: The changes in cardiorespiratory variables we observed with altitude were consistent with previous studies. Heart rate, respiratory rate and blood pressure increased whilst oxygen saturation reduced. Over time at altitude, respiratory rate and heart rate were maintained whilst there was a reduction in blood pressure towards sea level values. Oxygen saturations improved over time at altitude and the change in heart rate on exercise was reduced with acclimatization. In this small pilot study individuals with AMS may have a greater heart rate response to exercise than non-AMS subjects and this may warrant further investigation. CONCLUSIONS: The incidence of AMS in our study was low reflecting a conservative ascent profile. Further larger studies are necessary to fully assess the predictive value of cardiorespiratory variables in AMS.

Epidemiology of inflammatory bowel disease among participants of the Millennium Cohort: incidence, deployment-related risk factors, and antecedent episodes of infectious gastroenteritis.

BACKGROUND: Crohn's disease (CD) and ulcerative colitis (UC) are two pathotypes of inflammatory bowel disease (IBD) with unique pathology, risk factors and significant morbidity. AIM: To estimate incidence and identify IBD risk factors in a US military population, a healthy subset of the US population, using information from the Millennium Cohort Study. METHODS: Incident IBD was identified from medical encounters from 2001 to 2009 or by self-report. Our primary risk factor of interest, infectious gastroenteritis, was identified from medical encounters and self-reported post-deployment health assessments. Other potential risk factors were assessed using self-reported survey responses and military personnel files. Hazard ratios were estimated using Cox proportional hazards analysis. RESULTS: We estimated 23.2 and 21.9 diagnoses per 100 000 person-years, respectively, for CD and UC. For CD, significant risk factors included [adjusted hazard ratio (aHR), 95% confidence interval]: current smoking (aHR: 2.7, 1.4-5.1), two life stressors (aHR: 2.8, 1.4-5.6) and prior irritable bowel syndrome (aHR: 4.7, 1.5-15.2). There was no significant association with prior infectious gastroenteritis. There was an apparent dose-response relationship between UC risk and an increasing number of life stressors. In addition, antecedent infectious gastroenteritis was associated with almost a three-fold increase in UC risk (aHR: 2.9, 1.4-6.0). Moderate alcohol consumption (aHR: 0.4, 0.2-0.6) was associated with lower UC risk. CONCLUSIONS: Stressful conditions and the high risk of infectious gastroenteritis in deployment operations may play a role in the development of IBD in military populations. However, observed differences in risk factors for UC and CD warrant further investigation.

Differential detection of turkey coronavirus, infectious bronchitis virus, and bovine coronavirus by a multiplex polymerase chain reaction.

The objective of the present study was to develop a multiplex polymerase chain reaction (PCR) method for differential detection of turkey coronavirus (TCoV), infectious bronchitis coronavirus (IBV), and bovine coronavirus (BCoV). Primers were designed from conserved or variable regions of nucleocapsid (N) or spike (S) protein gene among TCoV, IBV, and BCoV and used in the same PCR reaction. Reverse transcription followed by the PCR reaction was used to amplify a portion of N or S gene of the corresponding coronaviruses. The PCR products were detected on agarose gel stained with ethidium bromide. Two PCR products, a 356-bp band corresponding to N gene and a 727-bp band corresponding to S gene, were obtained for TCoV isolates. In contrast, one PCR product of 356 bp corresponding to a fragment of N gene was obtained for IBV strains and one PCR product of 568 bp corresponding to a fragment of S gene was obtained for BCoV. There were no PCR products with the same primers for Newcastle disease virus, Marek's disease virus, turkey pox virus, pigeon pox virus, fowl pox virus, reovirus, infectious bursal disease virus, enterovirus, astrovirus, Salmonella enterica, Escherichia coli, and Mycoplasma gallisepticum. Performance of the assay with serially diluted RNA demonstrated that the multiplex PCR could detect 4.8x10(-3) microg of TCoV RNA, 4.6x10(-4) microg of IBV RNA, and 8.0x10(-2) microg of BCoV RNA. These results indicated that the multiplex PCR as established in the present study is a rapid, sensitive, and specific method for differential detection of TCoV, IBV, and BCoV in a single PCR reaction.

Observation and basis of improved blood flow to the distal latissimus dorsi muscle: a case for electrical stimulation prior to grafting.

OBJECTIVE: Dynamic cardiomyoplasty, using a functional graft of the latissimus dorsi muscle, has shown promise as a treatment for selected patients with advanced heart failure. The success of this approach depends on maintaining the viability of the muscle, whose distal portion is susceptible to ischaemic damage. We investigated the effects of surgical mobilization on regional muscle blood flow and the influence of electrical stimulation of the muscle. METHODS: Ten sheep were randomly assigned to two equal groups. In one group, the latissimus dorsi muscle was stimulated continuously in situ at 2 Hz for two weeks; in the other group, the muscle was not stimulated. Regional blood flows in the muscles were determined by a fluorescent microsphere technique. Serial measurements were made (a) under baseline conditions before intervention, (b) with the thoracodorsal artery occluded and (c) after interruption of the perforating collateral arteries. RESULTS: Surgical mobilization of the unstimulated latissimus dorsi muscles had little effect on blood flow in the proximal region, which remained at 93.1 +/- 16.9% of baseline (mean +/- SEM). The distal region was rendered significantly more ischaemic (55.8 +/- 13.5% of baseline, p < 0.002 compared to the proximal region). Electrical prestimulation abolished any significant proximodistal gradient in blood flow and improved distal muscle perfusion following mobilization (proximal vs. distal: 75.0 +/- 8.8 vs. 63.0 +/- 10.9%; p > 0.4). CONCLUSIONS: Distal muscle ischaemia occurred when the entire latissimus dorsi muscle was acutely elevated on the thoracodorsal pedicle alone. Electrical prestimulation of the muscle in situ improved the thoracodorsal perfusion of the distal muscle by abolishing the proximal-to-distal gradient in flow, with a substantial benefit to distal flow after mobilization. Although electrical stimulation is known to induce vascular proliferation, we argue that this effect of stimulation is brought about mainly by enhancement of the flow through anastomotic connections between proximal and distal arterial territories.

Surgical repair of pulmonary vein injury from blunt trauma.

Pulmonary vein deceleration injury is rare and patients can be deceptively stable for a period after injury. Quick diagnosis and transfer to the operating theatre is the only way to treat this potentially lethal injury successfully. Techniques of repair are a useful addition to the cardiovascular surgeon's repertoire.

Surgical site infection-a population-based study in Australian adults measuring the compliance with and correct timing of appropriate antibiotic prophylaxis.

Prophylaxis for surgical site infection (SSI) is often at variance with guidelines, despite the prevalence of SSI and its associated cost, morbidity, and mortality. The CareTrack Australia study, undertaken by a number of the authors, demonstrated that appropriate care (in line with evidence- or consensus-based guidelines) was provided at 38% of eligible SSI healthcare encounters. Here, we report the indicator-level CareTrack Australia findings for SSI prophylaxis. Indicators were extracted from Australian and international clinical guidelines and ratified by clinical experts. A sample designed to be representative of the Australian population was recruited (n=1154). Participants' medical records were reviewed and analysed for compliance with the five SSI indicators. The main outcome measure was the percentage of eligible healthcare encounters with documented compliance with indicators for appropriate SSI prophylaxis. Of the 35,145 CareTrack Australia encounters, 702 (2%) were eligible for scoring against the SSI indicators. Where antibiotics were recommended, compliance was 49% for contaminated surgery, 57% for clean-contaminated surgery and 85% for surgery involving a prosthesis: these fell to 8%, 10% and 14%, respectively (an average of 11%), when currently recommended timing of antibiotic administration was included. Where antibiotics were not indicated, 72% of patients still received them. SSI prophylaxis in our sample was poor; over two-thirds of patients were given antibiotics, whether indicated or not, mainly at the wrong time. There is a need for national agreement on clinical standards, indicators and tools to guide, document and monitor SSI prophylaxis, with both local and national measures to increase and monitor their uptake.

Lung graft preservation. Comparison of phosphate-buffered sucrose, modified EuroCollins, and University of Wisconsin solutions.

Phosphate-buffered sucrose (PBS) has been shown to be highly effective for renal graft storage. It may, therefore, be useful for lung graft storage. Recent studies have suggested a possible role for University of Wisconsin (UW) solution in lung preservation. The object of this study was to evaluate these two solutions in comparison with EuroCollins (EC) solution for lung graft preservation in an isolated rat lung model. Lungs were stored for 6 hr at 4 degrees C after a single pulmonary artery flush with either PBS with prostacyclin (n = 10), EC with prostacyclin (n = 5), or UW (n = 5) solution. Reperfusion of the isolated lung was carried out for 1 hr using a venovenous extracorporeal circulation from a ventilated support rat. The support animals and isolated lungs were ventilated with room air. Control values were obtained from lungs reperfused immediately after harvesting (n = 5). At 1 hr, PBS provided a similar level of protection to EC: pO2, 45 +/- 10 mmHg and 54 +/- 6 mmHg; graft blood flow, 4.1 +/- 1.2 ml/min and 3.5 +/- 0.42 ml/min; peak airway pressure, 32 +/- 2.5 mmHg and 36 +/- 3.6 mmHg; weight gain, 4.1 +/- 0.6 g and 4.2 +/- 0.6 g, respectively (P = NS). However, the UW group provided superior function, which was similar to the control group: pO2, 128 +/- 2.7 mmHg and 126 +/- 5 mmHg; graft blood flow, 9.9 +/- 0.4 ml/min and 10.2 +/- 0.8 ml/min; peak airway pressure, 17.6 +/- 0.4 mmHg and 16.5 +/- 0.6 mmHg; weight gain, 0.12 +/- 0.1 g and 0.19 +/- 0.13 g, respectively (P = NS). UW was superior in all parameters to PBS and EC (P < 0.001). This suggests that the renal solutions PBS and EC are inappropriate for lung graft preservation, and that the requirements of the lung during hypothermic storage differ from those of the kidney.

The use of a prostacyclin analog, iloprost, as an adjunct to pulmonary preservation with Euro-Collins solution.

The addition of prostaglandin to the single-flush technique of lung preservation is considered to enhance subsequent graft function. We have evaluated the use of the prostacyclin analog, Iloprost, in an animal model of unilateral lung transplantation. Group 1 (n = 5) received Iloprost as a pretreatment intravenously (20 ng/kg/min) and as an additive (20 ng/L) to 20 ml/kg of modified Euro-Collins solution. Group 2 (n = 5) received no Iloprost, either as pretreatment or added to the perfusate. Perfusate distribution within the lungs during flush perfusion was assessed using 99mTc-labelled microaggregates of albumin. After the initial preservation technique the lungs in both groups were stored for 6 hr in Euro-Collins solution at 4 degrees C. Thereafter, left lung transplantation was followed by ligation of the contralateral pulmonary artery and bronchus, rendering the animal completely dependent on the transplanted, stored lung. Preservation was assessed by animal survival, measurement of hemodynamic and blood gas data for 24 hr at a fixed FiO2 (0.4) and tidal volume (10 ml/kg), and at sacrifice by measurement of transplanted lung water. By these criteria, both group 1 and 2 lungs were well preserved. The addition of Iloprost to group 1 animals appeared to confer no measureable benefit in terms of lung cooling, perfusate distribution, postoperative graft function, or total lung water.

24-hour lung preservation: simplified versus conventional University of Wisconsin solution in a porcine model.

BACKGROUND: Experimentally, the University of Wisconsin solution (UW) has been shown to be superior to the EuroCollins solution (EC) for lung graft preservation. We showed previously that the inclusion of the trisaccharide raffinose as an impermeant in the UW is largely responsible for this superiority. In this study, we used a new porcine model of isolated lung reperfusion to evaluate the use of a simple solution of phosphate-buffered raffinose (PBr) for lung preservation. METHODS: Lungs were stored for 24 hr at 4 degrees C after a single pulmonary artery flush with either UW (n = 5) or PBr (n = 5) solution. Left lungs were ventilated with room air and reperfused for 4 hr by venovenous extracorporeal circulation from a support animal. Controls (n = 5) were flushed with UW and reperfused without storage. RESULTS: Control lungs performed better than those stored in either solution in terms of oxygenation (P = 0.034) and airway pressure (P = 0.032). There were no significant differences between the two stored groups for any parameters. Data for stored lungs after 4 hr of reperfusion (means with 95% confidence intervals) include oxygenation (mm Hg): control 101.6 (14.5), UW 85.2 (14.5), PBr 75.0 (14.5); blood flow (ml/ min): control 572 (90), UW 466 (90), PBr 468 (90); peak airway pressure (mm Hg): control 15.9 (3.0), UW 21.0 (3.0), PBr 22.6 (3.0); pulmonary artery pressure (mm Hg): control 17.5 (3.2), UW 22.3 (2.9), PBr 24.5 (2.9). Graft edema (percentage tissue water): control 86.4 (0.8), UW 89.9 (1.8), PBr 89.3 (1.0). CONCLUSION: PBr is a far simpler and less expensive alternative to UW, and appears to provide a similar level of lung graft protection.

Comparison of saccharides as osmotic impermeants during hypothermic lung graft preservation.

We have previously shown that the trisaccharide raffinose is largely responsible for the superior lung graft performance seen after storage in University of Wisconsin solution. To investigate the use of osmotic agents in perfusates for hypothermic lung graft storage, we compared saccharides of various molecular weights in an isolated rat lung model. Grafts were flushed with 1 of 6 preservation solutions (n=5 each group) containing either a monosaccharide (glucose [G] or fructose [F]), disaccharide (trehalose [T] or sucrose [S]), or trisaccharide (raffinose [R] or melezitose [M]. Grafts were stored for 6 hours at 4 degrees C, reperfused by a veno-venous circuit from an anesthetized support animal for 60 min, and ventilated with room air. The best graft function was seen when trisaccharides were used (PO2; R 126 +/- 3 mm Hg, M 129 +/- 3 mm Hg, blood flows: R 10.2 +/- 0.42 ml/min, M 10.3 +/- 0.22 ml/min). Disaccharides produced similar oxygenation (T 133 +/- 3 mm Hg, S 129 +/- 3 mm Hg) and flows (T 10.3 +/- 0.29 ml/min, S 9.7 +/- 0.4 ml/min) at 60 min, but initial flows were reduced. Monosaccharides produced the least satisfactory graft function, with impaired oxygenation (F 110 +/- 14 mm Hg, P<0.05; G 69 +/- 10 mm Hg, P<0.01) and blood flows (G 6.5 +/- 0.6 ml/min, F 9.1 +/- 0.6 ml/min, P<0.01 each). Only glucose-stored lungs demonstrated a significant decrease in compliance (P<0.01) and weight gain (P<0.01). The worst results were seen with glucose, which is the osmotic agent most commonly used for clinical lung storage. A solution containing a trisaccharide or disaccharide may be more appropriate for this purpose.

Modulation of lung reperfusion injury by nitric oxide: impact of inspired oxygen fraction.

BACKGROUND: Attempts to attenuate lung reperfusion injury by administration of inhaled nitric oxide have yielded conflicting results. We hypothesized that the inspired oxygen fraction may play an important role in determining the outcome of nitric oxide therapy. METHODS: Rat lungs were reperfused in a circuit incorporating a support animal either immediately after flushing (group A) or after 24-hr hypothermic storage (groups B-D). During the first 10 min of reperfusion, grafts were ventilated with 95% oxygen in groups A and B, 95% oxygen and 20 ppm nitric oxide in group C, and 20% oxygen and 20 ppm nitric oxide in group D. Ventilation during the subsequent 50 min of reperfusion was with 100% oxygen only, in all groups. RESULTS: Graft function in group B was poor compared to group A in terms of blood flow and pulmonary artery and peak airway pressures. In group C, although 5 out of 10 grafts functioned at control levels, the remainder performed poorly. Function in group D, on the other hand, was uniformly good. CONCLUSIONS: Inhaled nitric oxide can prevent lung reperfusion injury, but this effect may be compromised by concurrent ventilation with high oxygen concentrations.

Amelioration of lung ischemic injury with prostacyclin.

The single-flush technique of lung preservation is thought to be enhanced by prostaglandin treatment. In order to test this hypothesis, ten beagle dogs underwent thoracotomy and in situ flush perfusion of the excluded left lung with 30 ml/kg of cold, modified Euro-Collins' solution. Group 1 (n = 5) received pretreatment with 30 ng/kg/min of PGI2 by infusion and as an additive to the flush (20 micrograms/L). Group 2 (n = 5) received no PGI2 and served as controls. Following 60 min of warm ischemia, the left lung was reperfused, the contralateral lung excluded, and the animal ventilated at a fixed FiO2 of 0.4 for 4 hr. The severity of reperfusion injury was assessed by arterial oxygenation and hemodynamic measurements and, following sacrifice, by lung weight gain and bronchoalveolar lavage and ultrastructural studies. PGI2 therapy resulted in significant amelioration of reperfusion injury, with superior oxygenation at both 1 and 4 hr (PaO2 at 1 and 4 hr, respectively; PGI2: 145 mmHg +/- 17.0 and 114 +/- 11.2; no PGI2: 59 mmHg +/- 5.8 and 51 +/- 4.5; P less than 0.01 at both times), lower pulmonary vascular resistance index at 4 hr (PVRI; PGI2: 913 dynes sec cm-5m-2 +/- 91; no PGI2: 1239 +/- 68; P less than 0.05) and lower lung weight (PGI2: 76 g +/- 4; no PGI2: 146 +/- 10; P less than 0.001). Bronchoalveolar lavage studies revealed an influx of neutrophils following reperfusion that was less marked in the PGI2 group (increase in % neutrophils; PGI2: 50.4 +/- 6.7; no PGI2: 76.9 +/- 6.0; P less than 0.05). Lung injury score assessed by electron microscopy was lower in the PGI2 group (PGI2: 5.2 +/- 1.1; no PGI2; 8.1 +/- 0.5; P less than 0.05). It is concluded that PGI2 treatment is protective against ischemic lung injury in this model.

Hypertonic citrate solution as an alternative to modified Euro-Collins' solution for lung preservation.

In a canine model of acute ischemic lung injury, a hypertonic citrate solution (HTC) widely used for renal preservation in the United Kingdom, was compared with modified Euro-Collins' solution (ECS) currently the most widely clinically used pulmonary perfusate. Ten beagle dogs underwent left thoracotomy and exclusion of the left lung in situ. The lung was flushed with 30 ml/kg of either HTC or ECS and subjected to 60 min of warm ischemia. The circulation to the lung was then restored, the contralateral lung excluded, and the animal ventilated at a fixed FiO2 of 0.4 for 4 hr. Lung function was assessed by arterial oxygenation and hemodynamic measurements and, following sacrifice, by lung weight gain, bronchoalveolar lavage, and ultrastructural studies. Flush perfusion with HTC was associated with significantly less severe reperfusion injury, as determined by superior arterial oxygenation (PaO2 at 1 hr: HTC--152 mmHg [(95% confidence interval) CI] [122-182], ECS--59 [47-70]; PaO2 at 4 hr: HTC--124 [100-149], ECS--51 [42-61]), lower pulmonary vascular resistance index (PVRI at 4 hrs: HTC--838 dynes sec cm-5m-2 [651-1075], ECS--1233 [963-1588]); and lower lung weight (HTC--85 g [66-107], ECS--146 [114-184]). Bronchoalveolar lavage studies demonstrated an influx of neutrophils following reperfusion that was significantly less marked in the HTC group (increase in % neutrophils: HTC 24 [19-29], ECS 77 [72-82]). Lung injury assessed by electron microscopy tended to be less severe in the HTC animals. We conclude that HTC may offer an alternative superior to ECS for lung preservation.

Preservation of the lung. Comparison of topical cooling and cold crystalloid pulmonary perfusion.

Topical cooling of the lung was compared with cold crystalloid pulmonary artery perfusion with modified Euro-Collins solution in a canine model of unilateral left lung allotransplantation with ligation of the recipient's contralateral pulmonary artery and main bronchus. Lung preservation for 6 hours was achieved by topical cooling and storage at 4 degrees C after absorption atelectasis in five dogs and in a further five dogs by pulmonary arterial perfusion of Euro-Collins solution; 60 ml/kg at 4 degrees C, modified with MgSO4 6 mmol/L followed by storage at 4 degrees C. Dogs in the perfusion group were pretreated with an infusion of the synthetic analog of prostaglandin I2, iloprost (20 ng/kg/min). The ischemic times were 5.97 hours +/- 0.09 for the topical cooling group and 5.96 hours +/- 0.04 for the perfusion group. After transplantation, artificial ventilation at a fixed oxygen concentration was continued until the recipient's death or elective termination of the experiment at 24 hours. Assessment of pulmonary preservation was by animal survival, blood gas analyses, and measurement of lung weight and water in the transplanted lung. No animal in the topical cooling group survived more than 5.5 hours after transplantation; all perfusion recipients survived 24 hours. Oxygenation in the topical cooling group was significantly reduced 1 hour after contralateral ligation: Oxygen tension was 224.2 mm Hg +/- 5.8 before ligation and 92.6 mm Hg +/- 22.3 after ligation (p less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral injury during cardiopulmonary bypass: emboli impair memory.

OBJECTIVES: Cognitive deficits occur in up to 80% of patients after cardiac surgery. We investigated the influence of cerebral perfusion and embolization during cardiopulmonary bypass on cognitive function and recovery. METHODS: Cerebrovascular reactivity was measured in 70 patients before coronary operations in which nonpulsatile bypass was used. Throughout the operations, middle cerebral artery flow velocity and embolization were recorded by transcranial Doppler and regional oxygen saturation was recorded by near-infrared spectroscopy. Cognitive function was measured by a computerized battery of tests before the operation and 1 week, 2 months, and 6 months after surgery. Elderly patients undergoing urologic surgery served as controls. RESULTS: Cerebrovascular reactivity was impaired preoperatively in 49 patients. Median (interquartile range) regional cerebral oxygen saturation fell during bypass by 10% (6%-15%), indicating increased oxygen extraction, whereas mean middle cerebral flow velocity increased significantly by a median of 6 cm/s (both P <.0001, Wilcoxon), suggesting increased arterial tone. More than 200 emboli were detected in 40 patients, mainly on aortic clamping and release, when bypass was initiated, and during defibrillation. Cognitive function deteriorated more in patients having cardiopulmonary bypass than in control patients having urologic operations but recovered in most tests by 2 months. Measures of cerebral perfusion (poor cerebrovascular reactivity, low arterial pressures, and flow velocity in the middle cerebral artery) predicted poor attention at 1 week (r = 0.3, P <.01, Spearman). Emboli were associated with memory loss (r = 0.3, P <.02, Spearman). CONCLUSIONS: Cognitive deficits were common after cardiopulmonary bypass. Occult cerebrovascular disease was more severe than expected and predisposed to attention difficulties, whereas emboli caused memory deficits. We believe this to be the first report of differing cognitive effects from emboli and hypoperfusion.