Peri-operative risk factors for acute lung injury after elective oesophagectomy

Acute lung injury after oesophagectomy is well recognized butthe risk factors associated with its development are poorlydefined. We analysed retrospectively the effect of a numberof pre-, peri- and post-operative risk factors on the developmentof lung injury in 168 patients after elective oesophagectomyperformed at a single centre. The acute respiratory distresssyndrome (ARDS) developed in 14.5% of patients and acute lunginjury in 23.8%. Mortality in patients developing ARDS was 50%compared with 3.5% in the remainder. Features associated withthe development of ARDS included a low pre-operative body massindex, a history of cigarette smoking, the experience of thesurgeon, the duration of both the operation and of one-lungventilation, and the occurrence of a post-operative anastomoticleak. Peri-operative cardiorespiratory instability (measuredby peri-operative hypoxaemia, hypotension, fluid and blood requirementsand the need for inotropic support) was also associated withARDS. Acute lung injury after elective oesophagectomy is associatedwith intraoperative cardiorespiratory instability. Br J Anaesth 2001; 86: 633–8     

Quantification of atelectatic lung volumes in two different porcine models of ARDS

Background. Cyclic recruitment during mechanical ventilationcontributes to ventilator associated lung injury. Two differentpathomechanisms in acute respiratory distress syndrome (ARDS)are currently discussed: alveolar collapse vs persistent floodingof small airways and alveoli. We compare two different ARDSanimal models by computed tomography (CT) to describe differentrecruitment and derecruitment mechanisms at different airwaypressures: (i) lavage-ARDS, favouring alveolar collapse by surfactantdepletion; and (ii) oleic acid ARDS, favouring alveolar floodingby capillary leakage. Methods. In 12 pigs [25 (1) kg], ARDS was randomly induced,either by saline lung lavage or oleic acid (OA) injection, and3 animals served as controls. A respiratory breathhold manoeuvrewithout spontaneous breathing at different continuous positiveairway pressure (CPAP) was applied in random order (CPAP levelsof 5, 10, 15, 30, 35 and 50 cm H₂O) and spiral-CT scans of thetotal lung were acquired at each CPAP level (slice thickness=1mm). In each spiral-CT the volume of total lung parenchyma,tissue, gas, non-aerated, well-aerated, poorly aerated, andover-aerated lung was calculated. Results. In both ARDS models non-aerated lung volume decreasedsignificantly from CPAP 5 to CPAP 50 [oleic acid lung injury(OAI): 346.9 (80.1) to 96.4 (48.8) ml, P<0.001; lavage-ARDS:245 17.6) to 42.7 (4.8) ml, P<0.001]. In lavage-ARDS poorlyaerated lung volume decreased at higher CPAP levels [232 (45.2)at CPAP 10 to 84 (19.4) ml at CPAP 50, P<0.001] whereas inOAI poorly aerated lung volume did not vary at different airwaypressures. Conclusions. In both ARDS models well-aerated and non-aeratedlung volume respond to different CPAP levels in a comparablefashion: Thus, a cyclical alveolar collapse seems to be partof the derecruitment process also in the OA-ARDS. In OA-ARDS,the increase in poorly aerated lung volume reflects the specificinitial lesion, that is capillary leakage with interstitialand alveolar oedema. This study contains parts of the doctoral thesis of ChristinaHartmann.     

High-frequency oscillation in adolescents

Background. High-frequency oscillation (HFO) is a widely usedlung-protective ventilatory strategy in paediatric and neonatalacute lung injury. Its safe and effective use has been hinderedby inadequate recruitment of the lung during oscillation and,until recently, the lack of an adequately powered oscillatorfor use in adult practice. Methods. We present data from three adolescents with severeacute respiratory distress syndrome (ARDS) who received HFOwith the Sensormedics 3100B oscillator after failure of conventionalmechanical ventilation. A manual recruitment manoeuvre was usedin all patients prior to mechanical ventilation (conventionalor HFO) and following tracheal suctioning or disconnection fromthe ventilator. Changes in oxygenation index were used to assesstherapy. Results. All patients showed at least a 25% reduction in oxygenationindex within 2 h of HFO, with return to conventional ventilationafter 27--65 h. Conclusions. We found HFO, in conjunction with manual recruitmentand prone positioning, to be a well-tolerated mode of ventilationin adolescents with ARDS and who were unresponsive to conventionalventilation. Given this success we hope to renew interest inthis method for adults with ARDS, together with concurrent useof manual recruitment. Br J Anaesth 2002; 88: 708–11     

Ventilation by the Open Lung Concept in spite of traumatic lung herniation

Traumatic herniation of the lung is uncommon. We report a patientsuffering from multiple injuries including severe pulmonarycontusion and traumatic parasternal lung herniation, who developedacute respiratory distress syndrome. In spite of the lung herniation,we used mechanical ventilation according to the Open Lung Concept.Oxygenation improved rapidly, and early operative stabilizationwas possible. Br J Anaesth 2003; 90: 385–7     

Anaesthetist's responses to patients' self-reported drug allergies

Background. Patients with drug allergies are commonplace inanaesthetic practice. We investigated the incidence and natureof drug ‘allergies’ reported by surgical patientsattending a hospital pre-admission clinic, and went on to ascertainto what degree drug allergies recorded in the records influenceddrug prescribing during the patients’ hospital stay anddetermine whether any adverse events occurred in relation todrug prescribing in this population. Methods. Patients attending for anaesthetic assessment at aPre-Admission Clinic over a 30 week period were questioned concerningdrug allergies. Medical records of these patients were thenexamined after their hospitalization to assess medications prescribedduring that period. Results. Of 1260 patients attending the Pre-admission clinicduring the study period 420 (33.4%) claimed to have a totalof 644 individual drug ‘allergies’. The most commonagents implicated were antibiotics (n=272), opioid analgesics(n=118) and NSAIDs (n=62); the most common form of these reactionswere dermatological (n=254) and nausea and vomiting (n=124).There were 41 self-reports specifically of anaphylaxis and afurther 61 where there was significant respiratory system involvement. Conclusions. The majority of the self-reported allergies werein fact simply accepted adverse effects of the drugs concerned.The patients’ reported drug ‘allergy’ historywas generally well respected by anaesthetists and other medicalstaff. There were 13 incidents, mainly involving morphine, wherepatients were given a drug to which they had claimed a specificallergy. There were 101 incidents in 89 patients where drugsof the same pharmacological group as that of their allergicdrug were used. There were no untoward reactions in 84 patientswho had claimed a prior adverse reaction to penicillin who weregiven cephalosporins. There were no sequelae from any otherevents. While anaesthetists generally respected patients self-reported‘allergies', more attention needs to be paid to the accuraterecording of patients’ events and a clear distinctionshould be made both in medical records and to the patient betweentrue drug allergy and simple adverse drug reactions.     

Is pulmonary resistance constant, within the range of tidal volume ventilation, in patients with ARDS?

When managing patients with acute respiratory distress syndrome(ARDS), respiratory system compliance is usually consideredfirst and changes in resistance, although recognized, are neglected.Resistance can change considerably between minimum and maximumlung volume, but is generally assumed to be constant in thetidal volume range (V_T). We measured resistance during tidalventilation in 16 patients with ARDS or acute lung injury bythe slice method and multiple linear regression analysis. Resistancewas constant within V_T in only six of 16 patients. In the remainingpatients, resistance decreased, increased or showed complexchanges. We conclude that resistance within V_T varies considerablyfrom patient to patient and that constant resistance withinV_T is not always likely. Br J Anaesth 2001; 86: 176–82     

Influence of volatile anaesthetics on hypercapnoeic ventilatory responses in mice with blunted respiratory drive

Background. Subanaesthetic concentrations of volatile anaestheticssignificantly affect the respiratory response to hypoxia andhypercapnoeia. Individuals with an inherited blunted respiratorydrive are more affected than normal individuals. To test thehypothesis that subjects with blunted hypercapnoeic respiratorydrive are diversely affected by different anaesthetics, we studiedthe effects of three volatile anaesthetics on the control ofbreathing in C3H/HeJ (C3) mice, characterized by a blunted hypercapnoeicrespiratory response. Methods. Using whole body plethysmography, we assessed respiratoryrate (RR) and pressure amplitude in 11 male C3 mice at rest,during anaesthesia with isoflurane, sevoflurane or desflurane,and during recovery. To test respiratory drive, mice were exposedto 8% carbon dioxide. Data were analysed by two-way-analysisof variance with post hoc tests and Bonferroni correction. Results. RR was unaffected during sevoflurane anaesthesia upto 1.0 MAC. Likewise, sevoflurane at 1.5 MAC affected RR lessthan either isoflurane (P=0.0014) or desflurane (P=0.0048).The increased RR to a carbon dioxide challenge was blocked byall three anaesthetics even at the lowest concentration, andremained depressed during recovery (P<0.0001). Tidal volumewas unaffected by all three anaesthetics. Conclusions. In C3 mice, spontaneous ventilation was less affectedduring sevoflurane compared with either isoflurane or desfluraneanaesthesia. However, the RR response to hypercapnoeia was abolishedat 0.5 MAC for all the anaesthetic agents and remained depressedeven at the end of recovery. Our data suggest that differentvolatile anaesthetics have varying effects on the control ofbreathing frequency but all block the respiratory response tocarbon dioxide. Therefore, a genetic predisposition to a bluntedcarbon dioxide response represents a susceptibility factor thatinteracts with hypercapnoeic hypoventilation during maintenanceof anaesthesia and in the emergence from anaesthesia, regardlessof the agent used. Br J Anaesth 2004; 92: 697–703     

Lung density distribution in dynamic CT correlates with oxygenation in ventilated pigs with lavage ARDS

Background. Fast dynamic computed tomography (dCT) has beenused to assess regional dynamics of lung inflation and deflationprocesses. The aim of this study was to relate ventilation-inducedchanges in lung density distribution, as measured over severalrespiratory cycles by dCT, to oxygenation and shunt fractionin a lavage acute respiratory distress syndrome model. Methods. Six anaesthetized pigs underwent pressure-constantventilation (FI_O2=1.0, inspiratory:expiratory ratio=1:1) beforeand after induction of lung damage by saline lavage. Mean airwaypressure (P     

Respiratory failure after tracheal extubation in a patient with halo frame cervical spine immobilization--rescue therapy using the Combitube airway

A 78-yr-old man, with halo frame cervical spine immobilization,suffered rapid respiratory deterioration after tracheal extubationin the intensive care unit. Control of the airway was difficultas bag-valve-mask ventilation was ineffective, tracheal intubationwas known to be difficult from management of a previous episodeof respiratory failure on the ward, and laryngeal mask insertionproved impossible. Rescue therapy using a Combitube airway isdescribed and discussed. Br J Anaesth 2001; 86: 886–91     

Double lumen tube location predicts tube malposition and hypoxaemia during one lung ventilation

Background. Poor positioning of an endobronchial double lumentube (DLT) could affect oxygenation during one lung ventilation(OLV). We set out to relate DLT position to hypoxaemia and DLTmisplacement during OLV. Methods. We recruited 152 ASA physical status I–II patientsabout to have elective thoracic surgery. The trachea was intubatedwith a left-sided DLT. Tube position was assessed by fibre-opticscope and correction was made after patient positioning andduring OLV. If Pa_O2 was less than 10.7 kPa, the DLT positionwas checked and then PEEP, continuous positive airway pressure(CPAP), oxygen insufflation, or two lung ventilation (TLV) weretried. Results. The DLT was found to be misplaced in 49 patients (32%)after patient positioning, and in 38 patients (25%) during OLV.PEEP to the dependent lung, CPAP or apneic oxygen insufflationto the non-dependent lung, or brief periods of TLV, were appliedin 46 patients (30%). Patients who had DLT malposition afterplacing the patient in the lateral position had a greater incidenceof DLT malposition during OLV (59 vs 9%) and also required eachintervention more frequently (57 vs 10%). Patients with DLTmalposition during OLV also required interventions more often(84 vs 12%). Conclusions. Patients who have DLT malposition after placingthe patient in the lateral position had more DLT malpositionduring OLV and hypoxaemia during OLV. Br J Anaesth 2004; 92: 195–201     

Randomized study comparing the effects of hydroxyethyl starch solution with Gelofusine on pulmonary function in patients undergoing abdominal aortic aneurysm surgery

Background. Restoring blood flow to ischaemic tissue can causelung damage with pulmonary oedema. Hydroxyethyl starch (HES)solution, when used for volume replacement, may modify and reducethe degree of ischaemia–reperfusion injury. We comparedthe effects of HES solution with those of Gelofusine solutionon pulmonary function, microvascular permeability and neutrophilactivation in patients undergoing elective infrarenal abdominalaortic aneurysm surgery. Methods. Forty patients were randomized into two groups. Theanaesthetic technique was standardized. Lung function was assessedwith the PO₂/FI_O2 ratio, respiratory compliance, chest x-rayand a score for lung injury. Microvascular permeability wasdetermined by measuring microalbuminuria. Neutrophil activationwas determined by measurement of plasma elastase. Results. Four hours after surgery, the median (quartile values)PO₂/FI_O2 ratio was 40.3 (37.8, 53.1) kPa for the HES-treatedpatients compared with 33.9 (31.2, 40.9) kPa for the Gelofusine-treatedpatients (P<0.01, Mann–Whitney test). The respiratorycompliance was 80 (73.5, 80) ml cm^–1 H₂O inthe HES-treated patients compared with 60.1 (50.8, 73.3) mlcm^–1 H₂O in the Gelofusine-treated patients (P<0.01,Mann–Whitney test). The lung injury score 4 h after surgerywas less for the patients treated with HES compared with thepatients treated with Gelofusine (0.33 vs 0.71, P=0.01, Wilcoxonrank sum test). Mean (SD) plasma elastase was less in the HES-treatedpatients on the first postoperative day (1.96 (0.17) vs 2.08(0.24), P<0.05). The log mean microalbuminuria was less inthe HES-treated patients (0.41 vs 0.91 mg mmol^–1,P<0.05). This difference in microvascular permeability wasassociated with different volumes of colloid required to maintainstable cardiovascular measurements in the two groups of patientsstudied (3000 vs 3500 ml, P<0.01, Mann–Whitney test). Conclusion. Compared with Gelofusine, the perioperative pulmonaryfunction of patients treated with HES after abdominal aorticaneurysm surgery was better. Br J Anaesth 2004; 92: 61–6     

Novel approach to management of a posterior tracheal tear complicating percutaneous tracheostomy

We treated a patient who developed a posterior tracheal wallperforation and severe respiratory compromise following percutaneoustracheostomy, using a covered expandable metallic stent. Thestent was deployed under direct vision using rigid and fibreopticbronchoscopy. The defect was sealed and the right lung, whichhad been collapsed, was re-expanded. The patient was subsequentlyweaned from mechanical ventilation. Late complications includedhalitosis, which was treated with nebulized colistin sulphate,and the development of intratracheal granulation tissue, whichwas cleared using low power (10 W) Nd:YAG laser. Br J Anaesth 2004; 92: 437–9     

Non-invasive ventilation to avoid tracheal intubation in a patient with Guillain-Barré syndrome

A 72-yr-old man presented with respiratory failure secondaryto Guillain-Barré syndrome. Although the criteria formechanical ventilation were satisfied, the absence of weaknessof the bulbar muscles allowed the safe use of non-invasive ventilationfor 2 weeks in this patient. Invasive ventilation and tracheostomywere avoided and the patient made a good recovery. Br J Anaesth 2003; 91: 913--16     

Constipation and its implications in the critically ill patient

Background. Motility of the lower gut has been little studiedin intensive care patients. Method. We prospectively studied constipation in an intensivecare unit of a university hospital, and conducted a nationalsurvey to assess the generalizability of our findings. Results. Constipation occurred in 83% of the patients. Moreconstipated patients (42.5%) failed to wean from mechanicalventilation than non-constipated patients (0%), P<0.05. Themedian length of stay in intensive care and the proportion ofpatients who failed to feed enterally were greater in constipatedthan non-constipated patients (10 vs 6.5 days and 27.5 vs 12.5%,respectively (NS)). The survey found similar observations inother units. Delays in weaning from mechanical ventilation andenteral feeding were reported by 28 and 48% of the units surveyed,respectively. Conclusions. Constipation has implications for the criticallyill. Br J Anaesth 2003; 91: 815–19     

Hypoxia from vasculitic pulmonary haemorrhage improved by prone position ventilation

Ventilation in the prone position is used in patients with acuterespiratory distress syndrome (ARDS), although data supportingthis strategy are limited, and benefit for patients with otherconditions is unclear. The patient in this report had severehypoxaemia from diffuse alveolar haemorrhage caused by vasculitiswith positive antineutrophil cytoplasmic antibodies (ANCA).Ventilation in the prone position improved oxygenation dramatically.This improvement was initially maintained when returned supine,accompanied by increased ventilation. Prone ventilation wasused on three consecutive days for 10, 14 and 15 h, respectively.Prone ventilation could improve oxygenation by better ventilation–perfusion(V/Q) matching and improved drainage of blood from the dorsallung. The improved oxygenation in this patient should encouragethe use of prone ventilation in other patients with pulmonaryhaemorrhage and severe hypoxia. Br J Anaesth 2004; 92: 754–7     

Spinal cord stimulation in complex regional pain syndrome: cervical and lumbar devices are comparably effective

Background. Spinal cord stimulation (SCS) has been used since1967 for the treatment of patients with chronic pain. However,long-term effects of this treatment have not been reported.The present study investigated the long-term effects of cervicaland lumbar SCS in patients with complex regional pain syndrometype I. Methods. Thirty-six patients with a definitive implant wereincluded in this study. A pain diary was obtained from all patientsbefore treatment and 6 months and 1 and 2 years after implantation.All patients were asked to complete a seven-point Global PerceivedEffect (GPE) scale and the Euroqol-5D (EQ-5D) at each post-implantassessment point. Results. The pain intensity was reduced at 6 months, 1 and 2years after implantation (P<0.05). However, the repeatedmeasures ANOVA showed a statistically significant, linear increasein the visual analogue scale score (P=0.03). According to theGPE, at least 42% of the cervical SCS patients and 47% of thelumbar SCS patients reported at least ‘much improvement’.The health status of the patients, as measured on the EQ-5D,was improved after treatment (P<0.05). This improvement wasnoted both from the social and from the patients’ perspective.Complications and adverse effects occurred in 64% of the patientsand consisted mainly of technical defects. There were no differencesbetween cervical and lumbar groups with regard to outcome measures. Conclusion. SCS reduced the pain intensity and improves healthstatus in the majority of the CRPS I patients in this study.There was no difference in pain relief and complications betweencervical and lumbar SCS. Br J Anaesth 2004; 92: 348–53     

Strategies to reduce ventilator-associated lung injury (VALI)

Optimal management of the acute respiratory distress syndrome (ARDS) requires prompt recognition, treatment of the underlying cause and the prevention of secondary injury. Ventilator-associated lung injury (VALI) is one of the several iatrogenic factors that can exacerbate lung injury and ARDS. Reduction of VALI by protective low tidal volume ventilation is one of the only interventions with a proven survival benefit in ARDS. There are, however, several factors inhibiting the widespread use of this technique in patients with established lung injury. Prevention of ARDS and VALI by detecting at-risk patients and implementing protective ventilation early is a feasible strategy. Detection of injurious ventilation itself is possible, and potential biological markers of VALI have been investigated. Finally, facilitation of protective ventilation, including techniques such as extracorporeal support, can mitigate VALI.     

Improvement of 'dynamic analgesia' does not decrease atelectasis after thoracotomy

There is still controversy concerning the beneficial aspectsof ‘dynamic analgesia’ (i.e. pain while coughingor moving) on the reduction of postoperative atelectasis. Inthis study, we tested the hypothesis that thoracic epiduralanalgesia (TEA) prevents these abnormalities as opposed to multimodalanalgesia with i.v. patient controlled analgesia (i.v. PCA)after thoracotomy. Fifty-four patients undergoing thoracotomy(lung cancer) were randomly assigned to one of the two groups.Clinical respiratory characteristics, arterial blood gas, andpulmonary function tests (forced vital capacity and forced expiratoryvolume in 1 s) were obtained before surgery and on the next3 postoperative days. Atelectasis was compared between the twogroups by performing computed tomography (CT) scan of the chestat day 3. Postoperative respiratory function and arterial bloodgas values were reduced compared with preoperative values (mean(SD) FEV₁ day 0: 1.1 (0.3) litre; 1.3 (0.4) litre) but therewas no significant difference between groups at any time. PCAand TEA provided a good level of analgesia at rest (VAS day0: 21 (15/100); 8 (9/100)), but TEA was more effective for analgesiaduring mobilization (VAS day 0: 52 (3/100); 25 (17/100)). CTscans revealed comparable amounts of atelectasis (expressedas a percentage of total lung volume) in the TEA (7.1 (2.8)%)and in the i.v. PCA group (6.71 (3.2)%). There was no statisticaldifference in the number of patients presenting with at leastone atelectasis of various types (lamellar, plate, segmental,lobar). Br J Anaesth 2001; 87: 564–9     

Antiemetic and analgesic-sparing effects of diphenhydramine added to morphine intravenous patient-controlled analgesia

Background. This study was designed to examine the analgesicand dose-related antiemetic efficacy of diphenhydramine–morphinemixture for intravenous patient-controlled analgesia (PCA). Methods. Healthy women, undergoing abdominal total hysterectomywere recruited to this double-blinded randomized placebo-controlledstudy. Patients were randomly allocated to one of three groups(n=40 each). In group 1, patients received saline at inductionand morphine 1 mg ml^–1 alone for postoperative PCA. Patientsin groups 2 and 3 received diphenhydramine 30 mg i.v. at inductionand were given a 1.2:1 or a 4.8:1 ratio, respectively, of diphenhydramine–morphinemixture for postoperative PCA. Results. A total of 112 patients completed the study. The incidenceof postoperative nausea (31.6% vs 67.6%, P<0.01) and vomiting(15.8% vs 40.5%, <0.05) was significantly lower in group3 than in group 1. Furthermore, the incidence of severe nauseawas significantly lower in group 3 than in group1 (2.6% vs 24.3%,P<0.05). The rescue antiemetic requirements were also significantlyless in group 3 than in group 1 (5.3% vs 24.3%, P<0.05).However, there was no significant difference between group 2and group 1 in any of the comparisons. Pain intensity, 24-hmorphine consumption and diphenhydramine-related side-effects,such as sedation or dry mouth, did not differ among the threegroups. Conclusion. An initial bolus of diphenhydramine 30 mg at anaestheticinduction followed by postoperative PCA with a 4.8:1, but not1.2:1, diphenhydramine–morphine mixture provides an effectiveantiemetic efficacy without morphine-sparing effects.     

Changes in serum albumin concentration and volume expanding effects following a bolus of albumin 20% in septic patients

Background. Patients with systemic sepsis develop a capillaryleak syndrome, and serum –albumin concentration decreases.Hyperoncotic albumin infusion can be used for volume expansionin these patients, but the degree and duration of effect arenot well described. We assessed volume expansion by albumin20% infusion and compared the retention of infused albumin inseptic patients and healthy controls. Methods. We gave albumin 20%, 200 ml as a rapid infusion to70 patients with septic shock and 26 controls. Blood sampleswere taken before and 1, 5, 15, 30, 60, 120 and 240 min afterthe infusion for measurement of serum albumin concentrationand haematocrit. Haemodilution and the percentage of administeredalbumin remaining intravascularly at each time were calculated. Results. The mean proportion of the increase in albumin remainingat 4 h was 68.5 (SD 10)% in septic patients and 79 (5)% in controls(P<0.001). The albumin 20%, 200 ml caused a secondary fluidresorption and volume expansion maximal at 30 min, equivalentto a 430 ml infusion in septic patients and 500 ml in controls. Conclusions. After giving albumin, serum albumin concentrationsdecrease significantly faster in septic patients than in healthycontrols. Br J Anaesth 2004; 92: 821–6