Joseph E. Arrowsmith

Cardiopulmonary bypass management and neurologic outcomes: an evidence-based appraisal of current practices.

Neurologic complications after cardiac surgery are of growing importance for an aging surgical population. In this review, we provide a critical appraisal of the impact of current cardiopulmonary bypass (CPB) management strategies on neurologic complications. Other than the use of 20–40 &mgr;m arterial line filters and membrane oxygenators, newer modifications of the basic CPB apparatus or the use of specialized equipment or procedures (including hypothermia and “tight” glucose control) have unproven benefit on neurologic outcomes. Epiaortic ultrasound can be considered for ascending aorta manipulations to avoid atheroma, although available clinical trials assessing this maneuver are limited. Current approaches for managing flow, arterial blood pressure, and pH during CPB are supported by data from clinical investigations, but these studies included few elderly or high-risk patients and predated many other contemporary practices. Although there are promising data on the benefits of some drugs blocking excitatory amino acid signaling pathways and inflammation, there are currently no drugs that can be recommended for neuroprotection during CPB. Together, the reviewed data highlight the deficiencies of the current knowledge base that physicians are dependent on to guide patient care during CPB. Multicenter clinical trials assessing measures to reduce the frequency of neurologic complications are needed to develop evidence-based strategies to avoid increasing patient morbidity and mortality.

Neuroprotection of the Brain During Cardiopulmonary Bypass A Randomized Trial of Remacemide During Coronary Artery Bypass in 171 Patients

BACKGROUND AND PURPOSE Neuropsychological impairment may follow coronary artery bypass surgery as a result of peroperative cerebral microembolism. The hypothesis that remacemide, an NMDA receptor antagonist, would provide protection against such ischemic damage has been tested in a randomized trial. METHODS One hundred seventy-one patients undergoing coronary artery bypass surgery by a single cardiothoracic surgical team were randomized to receive remacemide (up to 150 mg every 6 hours) or placebo from 4 days before to 5 days after their bypass procedure. Peroperative monitoring included an estimate of the number of microembolic events detected by transcranial Doppler ultrasonography of the middle cerebral artery. A battery of 9 neuropsychological tests was administered before and 8 weeks after surgery. RESULTS The proportion of patients showing a decline in performance of 1 SD or more in 2 or more tests was reduced in the treated group (9% versus 12%), but this was not statistically significant. On the other hand, overall postoperative change (reflecting learning ability in addition to reduced deficits) was more favorable in the remacemide group, which demonstrated significantly greater improvement in a global z score (P=0.028) and changes in 3 individual tests (P<0.05). The 2 patient groups were well matched, including for the burden of microembolic events. CONCLUSIONS This is the first study to show statistically significant drug-based neuroprotection during cardiac surgery. In addition to offering improvement in cerebral outcome for such at-risk patients, it supports the hypothesis that drugs acting on the excitotoxic mechanism of ischemic cerebral damage can be effective in humans.

The value of routine microbial investigation in community-acquired pneumonia

The way in which microbiological investigations are used in routine clinical practice and the value of such tests in directing antibiotic prescribing, was studied in adults admitted to hospital with a diagnosis of community-acquired pneumonia. One-hundred and twenty-two consecutive patients admitted to one teaching and one district general hospital were studied between April 1988 and March 1989. Blood cultures were performed in 81% of cases, sputum was examined in 45% and complete serological tests were performed in 28%. No causative pathogen was found in 74% of cases and results of microbial tests directed a change in antibiotic therapy in only 8% of cases. Routine microbial investigation of all adults admitted to hospital with community-acquired pneumonia is unhelpful and probably unnecessary. We suggest a strategy for microbial investigation linked to initial illness severity to replace the current haphazard approach.

Successful Extracorporeal Membrane Oxygenation Support After Pulmonary Thromboendarterectomy

BACKGROUND Pulmonary thromboendarterectomy (PTE) is the treatment of choice for patients with chronic thromboembolic pulmonary hypertension. However, some patients develop severe cardiorespiratory compromise soon after separating from cardiopulmonary bypass, either from early reperfusion pulmonary edema or right ventricular failure secondary to residual pulmonary hypertension. Since 2005 we have used venoarterial extracorporeal membrane oxygenation (ECMO) support in this group that has no other therapeutic option. We review our experience of early ECMO support in the severely compromised patients post-PTE. METHODS We conducted a retrospective review of all patients undergoing PTE from a single national referral center between August 2005 and August 2007. RESULTS One hundred twenty-seven consecutive patients underwent PTE surgery. Seven patients (5.5%) had extreme cardiorespiratory compromise in the immediate postoperative period and required venoarterial ECMO support. Their mean age was 51.3 years with 3 males. When compared with patients not requiring ECMO, these patients had significantly poorer hemodynamic indices before the operation with mean pulmonary artery pressure of 62 mm Hg versus 51 mm Hg (p = 0.02) and pulmonary vascular resistance of 907 dynes/sec/cm(-5) versus 724 dynes/s(-1)/cm(-5) (p < 0.02). Mean duration of support was 119 hours (49 to 359 hours). Five patients were successfully weaned from ECMO support (73%) and 4 left the hospital alive, giving a salvage rate of 57%. For those who did not require ECMO support, hospital mortality was 4.2%. CONCLUSIONS Early venoarterial ECMO support has a role as rescue therapy post-PTE in patients with severe compromise who would probably otherwise die.

Circulatory arrest versus cerebral perfusion during pulmonary endarterectomy surgery (PEACOG): a randomised controlled trial

BACKGROUND For some surgical procedures to be done, a patients blood circulation needs to be stopped. In such situations, the maintenance of blood flow to the brain is perceived beneficial even in the presence of deep hypothermia. We aimed to assess the benefits of the maintenance of antegrade cerebral perfusion (ACP) compared with deep hypothermic circulatory arrest (DHCA). METHODS Patients aged 18-80 years undergoing pulmonary endarterectomy surgery in a UK centre (Papworth Hospital, Cambridge) were randomly assigned with a computer generated sequence to receive either DHCA for periods of up to 20 min at 20°C or ACP (1:1 ratio). The primary endpoint was change in cognitive function at 12 weeks after surgery, as assessed by the trail-making A and B tests, the Rey auditory verbal learning test, and the grooved pegboard test. Patients and assessors were masked to treatment allocation. Primary analysis was by intention to treat. The trial is registered with Current Controlled Trials, number ISRCTN84972261. FINDINGS We enrolled 74 of 196 screened patients (35 to receive DHCA and 39 to receive ACP). Nine patients crossed over from ACP to DHCA to allow complete endarterectomy. At 12 weeks, the mean difference between the two groups in Z scores (the change in cognitive function score from baseline divided by the baseline SD) for the three main cognitive tests was 0·14 (95% CI -0·14 to 0·42; p=0·33) for the trail-making A and B tests, -0·06 (-0·38 to 0·25; p=0·69) for the Rey auditory verbal learning test, and 0·01 (-0·26 to 0·29; p=0·92) for the grooved pegboard test. All patients showed improvement in cognitive function at 12 weeks. We recorded no significant difference in adverse events between the two groups. At 12 weeks, two patients had died (one in each group) [corrected]. INTERPRETATION Cognitive function is not impaired by either ACP or DHCA. We recommend circulatory arrest as the optimum modality for patients undergoing pulmonary endarterectomy surgery. FUNDING J P Moulton Charitable Foundation.

The oesophageal Doppler monitor.

The oesophageal Doppler monitor, described in the early 1970s1 and subsequently refined by Singer,2 provides a safe and minimally invasive means of continuously monitoring the circulation. A paper in this weeks issue describes using the oesophageal Doppler monitor to guide intraoperative fluid resuscitation in elderly patients undergoing repair of proximal femoral fractures (p 909).3 These patients are typically managed with only minimal intraoperative monitoring, and the paper thus raises questions about the role of invasive intraoperative monitoring. Similar questions have recently been raised about the role and use of pulmonary artery catheters.4 The oesophageal Doppler monitor measures blood flow velocity in the descending thoracic aorta using a flexible ultrasound probe about the size of a nasogastric tube. When combined with a nomogram based estimate of aortic cross sectional area (derived from the patients age, height, and weight), it allows haemodynamic variables, including stroke volume and cardiac output, to be calculated. Despite several potential sources of error, there is good correlation, at least in adults, between measures of …

Nasotracheal intubation in the presence of frontobasal skull fracture

PurposeTo present a case of maxillofacial trauma and basal skull fracture (BSF) in whom nasotracheal intubation (NTI) was successfully used, without complication, to facilitate surgical fixation. To present alternative methods of airway management in this situation and to review the evidence supporting the notion that NTI is contraindicated in the presence of basal skull fracture.Clinical featuresA 17-yr-old man was referred for surgical fixation of bilateral mandibular fractures. Cranial computed tomography revealed intracranial air and blood in all four sinuses and distortion of the nasal passage on the right. There was no cerebral injury and the left nasal passage appeared patent. In order to facilitate intraoperative intermaxillary fixation fibreoptic NTI was undertaken in preference to tracheostomy. The patient made an uneventful recovery without evidence of meningitis or direct cerebral injury.ConclusionIn selected patients NTI may be performed in the presence of BSF Available evidence suggests that BSF should not be regarded as an absolute contraindication to NTI.ObjectifPrésenter un cas de traumatisme maxillo-facial avec fracture de la base du crâne (FBS) chez qui une intubation nasotrachéale (INT) a été utilisée efficacement et sans complications pour une ostéosynthèse chirurgicale. Présenter des alternatives pour le contrôle des voies aériennes et revoir pourquoi on a toujours considéré l’INT comme contre-indiquée en présence d’une fracture de la base du crâne.Éléments cliniquesUn homme de 17 ans a été référé pour ostéosynthèse chirurgicale de fractures mandibulaires bilatérales. La tomographie axiale révélait la présence d’air intracrânien et du sang dans les quatre sinus avec déformation des voies nasales du côté droit. Il n’y avait pas de lésion cérébrale et les voies nasales gauches semblaient perméables. Dans le but de faciliter l’ostéosynthèse intermaxillaire, une INT par fibroscopie a été effectuée de préférence à une trachéotomie. Le patient a récupéré normalement sans évidence de méningite ni de blessure cérébrale directe.ConclusionChez des patients choisis, l’INT demeure possible en présence de FBC. Les données disponibles suggèrent de ne pas considérer une FBC comme une contre-indication absolue à l’INT.

The impact of intra-operative transoesophageal echocardiography on cardiac surgical practice

The use of transoesophageal echocardiography during cardiac surgery has increased dramatically and it is now widely accepted as a routine monitoring and diagnostic tool. A prospective study was carried out between September 2004 and September 2007, and included all patients in whom intra‐operative echocardiography was performed, 2 473 (44%) out of a total of 5 591 cases. Changes to surgery were subdivided into predictable (where echocardiographic examination was planned specifically to guide surgery) and unpredictable (new pathology not diagnosed pre‐operatively). A change in the planned surgical procedure was documented in 312 (15%) cases. In 216 (69%) patients the changes were predictable and in 96 (31%) they were unpredictable. The number of predictable changes increased between 2004–5 and 2006–7 (8% vs 13%, p = 0.025). In these cases, intra‐operative echocardiography was specifically requested by the surgeon to help determine the operative intervention. This has implications for consent and operative risk, which have yet to be fully determined.

Consensus statement: minimal criteria for reporting the systemic inflammatory response to cardiopulmonary bypass.

The lack of established cause and effect between putative mediators of inflammation and adverse clinical outcomes has been responsible for many failed anti-inflammatory interventions in cardiopulmonary bypass (CPB). Candidate interventions that impress in preclinical trials by suppressing a given inflammation marker might fail at the clinical trial stage because the marker of interest is not linked causally to an adverse outcome. Alternatively, there exist examples in which pharmaceutical agents or other interventions improve clinical outcomes but for which we are uncertain of any antiinflammatory mechanism. The Outcomes consensus panel made 3 recommendations in 2009 for the conduct of clinical trials focused on the systemic inflammatory response. This panel was tasked with updating, as well as simplifying, a previous consensus statement. The present recommendations for investigators are the following: (1) Measure at least 1 inflammation marker, defined in broad terms; (2) measure at least 1clinical end point, drawn from a list of practical yet clinically meaningful end points suggested by the consensus panel; and(3) report a core set of CPB and perfusion criteria that maybe linked to outcomes. Our collective belief is that adhering to these simple consensus recommendations will help define the influence of CPB practice on the systemic inflammatory response, advance our understanding of causal inflammatory mechanisms, and standardize the reporting of research findings in the peer-reviewed literature.

Neurologic risk assessment, monitoring and outcome in cardiac surgery☆

EUROLOGIC INJURY after cardiac surgery encompasses a wide spectrum of clinical entities ranging from the rare, fatal cerebral catastrophe to considerably more common psychiatric, neuropsychologic, and behavioral changes. A major neurologic complication after otherwise successful surgery represents a devastating outcome for both the patient and the immediate family. The social and economic impact of unemployment and the requirement for long-term rehabilitation or institutional care are significant. ~,2 Despite steady increases in average patient age as well as the prevalence and severity of other risk factors thought to contribute to adverse neurologic outcome in the cardiac surgical population, the incidence of these complications has fallen. 1.3 Because most patients undergoing cardiac surgery in the 1990s can reasonably expect to survive without significant long-term neurologic impairment, justifying the indiscriminate use of putative pharmacologic neuroprotectants or recommending the universal adoption of novel neuroprotective strategies that may significantly increase operating room time and cost is difficult. A more effective strategy is to reserve specific preventive or therapeutic interventions for patients who are at the greatest risk for neurologic or neuropsychologic dysfunction. Alternatively, minimally invasive or noninvasive monitors of cerebral function could be used in high-risk patients to detect intraoperative cerebral dysfunction and allow early deployment of potentially beneficial interventions. The purpose of this review is to assist in determining which patients are at increased risk for perioperative neurologic or neuropsychologic injury,