Extracorporeal CO2 removal

A 42 year old man presented with a week-long history of increasing shortness of breath, cough  (productive of purulent sputum) and fevers on a background of significant chronic lung disease. He had a ten year history of interstitial lung disease and was on the waiting list for a lung transplant. He used oxygen at a rate of 2 litres per minute at home, 24 hours a day. His usual exercise tolerance of 200 metres had been significantly reduced for the past week. His regular medications included seretide and salbutamol inhalers, lansoprazole, azathioprine, prednisolone alendronate.

On arrival in hospital, he was alert and orientated. He had a patent airway, but was tachypnoeic (rate of 50/minute) using his respiratory accessory muscles and a tracheal tug was evident. An arterial blood gas revealed type two respiratory failure (pH 7.26; pO2 8.14, pCO2 7.52 on 15 liters/min of face mask oxygen). He was hypotensive (80/40mmHg) and tachycardic (130/minute, sinus rhythm). A pyrexia of 39.2°C was recorded. Blood results showed normal renal function, a slightly elevated white cell count of 14.

The patient was admitted to the high dependency for close monitoring in view of his history and presentation. He was commenced on treatment for a presumed infection (viral or bacterial) with oseltamivir, co-amoxiclav and clarithromycin and given three “pulsed” doses (750mg) of methylprednisolone. He remained stable for the next twelve hours.

Early the next morning, he became very hypoxic (oxygen saturations less than 50%), bradycardic (<35 beats per minute) and had a brief hypoxic respiratory arrest. He received 1 cycle of cardiopulmonary resuscitation and was intubated. There was subsequently a return of spontaneous circulation.

The next 24 hours involved a period of difficulty with ventilation. His peak airway pressures were very high, despite being paralysed and a low volume/high respiratory rate strategy being employed. He was discussed with a tertiary respiratory centre and it was decided that he should be transferred for insertion of a pumpless arteriovenous interventional lung assist (for extracorporeal carbon dioxide removal) as a bridge prior to lung transplantation. He had formal ultrasound measurement of his femoral arteries. His left common femoral artery was widely patent (AP and transverse diameter of 8-9mm throughout), but the right was only 4-5mm throughout.

In the meantime, his peak airway pressures were consistently between 35 and 40cmH2O, despite tidal volumes of 230ml, 3.8ml/kg). With a rate of 32-35 breaths per minute, his pH was  initially maintained above 7.2, with a pCO2 of 9-11kPa. Over the course of the next few hours, this became increasingly difficult to achieve. His oxygen requirements did not escalate (an FiO2 of 0.6 provided a pO2 of 8-9kPa). When his pCO2 increased to 15.4kPa and his pH dropped to 7.17, further adjustments were made and the PEEP decreased to 5cmH2O from 10cmH2O. His noradrenaline requirements were increasing and with the aid of the cardiac output monitoring, he was cautiously given fluid with a good response.

He was transferred to the centre in which a lung transplant could be performed within hours of the referral. A Novalung device was inserted and he underwent a bilateral lobar lung transplant several days later. He was in hospital for 6 weeks and made a very good long-term recovery. At six months, he was extremely well and was undertaking his activities of daily living completely normally with stable lung function. He even managed to complete an eight mile bike ride.

What is the rationale for extracorporeal lung assist?
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Arthrogryposis & Paediatric Difficult Airway

EMERGENCY MANAGMENT OF A DIFFICULT AIRWAY IN AN INFANT WITH ARTHROGRYPOSIS MULTIPLEX CONGENITA

A 4 month old infant with arthropgryposis multiplex congenital was admitted to the paediatric assessment unit. The infant had been acutely unwell over the preceding 12 hours with respiratory compromise and a productive cough with green sputum. He had signs of respiratory distress with a RR of 40, pulse oximetry showed SpO2 of 85% on air and only 90% with a facemask, reservoir bag and high flow oxygen. It was felt that the infant would need to be intubated and ventilated. Two months before the infant had had a respiratory arrest on the neonatal ward and was unable to be intubated. That situation was resolved by mask ventilation and rescue with an LMA. There were obvious concerns that direct laryngoscopy would be unsuccessful and may precipitate a terminal decline in the patient’s condition.

The infant’s breathing was supported by bag/mask ventilation whilst he was transferred to an ENT theatre. Further anaesthetic support and an ENT surgeon were sought. I.v. access was established through a scalp vein. Ventilation was switched to an Ayres T piece with Jackson-Rees modification. Induction of anaesthesia was initiated with sevoflurane and oxygen. Direct laryngoscopy showed a Lehane and Cormack grade 4 view.

A rigid bronchoscope with video camera monitor was used by the ENT surgeon to obtain a view of the glottis. An epidural catheter was placed down the side port of the bronchoscope and was directed through the vocal cords. The bronchoscope was removed and a fine bore suction catheter was railroaded over the epidural catheter to give more stiffness. The positions of the end of the catheters were checked with the bronchoscope. A size 3.0cm uncuffed endotracheal tube was then railroaded over the catheters into trachea. Position and length were confirmed with the bronchoscope and ventilation was continued. The arrangement is shown in Figure 1.

The child was then transferred to the adult ICU where a retrieval team arrived to transfer the patient to a PICU.

What is arthrogryposis? Describe some methods for achieving control of the difficult paediatric airway.Read More »

Transplantation After Brainstem Death

A 38-year-old previously fit man suffered a grade five subarachnoid haemorrhage. Attempts at coiling failed and he suffered a catastrophic rebleed on-table whereupon his pupils became fixed and dilated. After a suitable sedation washout period he underwent testing which confirmed brainstem death at which point he was referred to the specialist nurse for organ donation. Following counselling of the family and appropriate assessment, donation of his kidneys, liver and heart was agreed.

Upon confirmation of brainstem death, mechanical ventilation was continued to ensure PaO2 greater than 10 kPa and limit peak inflation pressure to less than 30 cmH20. Vasoactive support was switched from noradrenaline to vasopressin 0.02 iu/kg/min. Methylprednisolone and intravenous triiodothyronine were administered whilst awaiting harvest. Blood antibody testing for HIV1+2, Hepatitis B and C, HTLV-1 and CMV IgG were all negative. A transthoracic echocardiogram confirmed good biventricular function; following discussion with the transplant retrieval team a pulmonary artery catheter was floated. Clinical measurements of cardiac output and mixed venous oxygen saturation were satisfactory. Adequate hydration was maintained with crystalloid by infusion and glucose control optimised in the range 8-10 mmol/L with insulin. The dedicated retrieval team performed the organ retrieval eighteen hours after confirmation of brainstem death.

How can we optimise organ function for organ donation?Read More »

Management of Inhalational Injury

A 30-year-old man with no significant past medical history was admitted to ED from a house fire started by a piece of faulty electrical equipment. There were superficial skin burns only but some evidence of a possible inhalation injury with singed nasal hairs and a hoarse voice. Coughing resulted in expectoration of carbonaceous sputum with some haemoptysis. Arterial blood gas analysis revealed a PaO2 of 10.4 kPa on 40% oxygen a carboxyhaemoglobin level of 18%.

Semi-elective endotracheal intubation was performed using an uncut orotracheal tube. Ventilatory parameters were adjusted to give a tidal volume of 6-8 ml/kg and plateau pressure of less than 30 cmH20. Recruitment manouveres were performed to give an optimum compliance in the region of 40-50 ml/cmH20 with a positive end-expiratory pressure of 8 H20. The inspired fraction of oxygen was kept high (i.e. greater than 60%) until there was a fall of the carboxyhaemoglobin level to less than 5% at which point downwards titration was performed as guided by a target SpO2 of 94%.

Fibreoptic bronchoscopy was performed approximately six hours after admission to intensive care which demonstrated carbonaceous colonisation of the lower respiratory tract and areas of erythematous and denuded epithelium. Within 12 hours of intubation significant oedema of the face and upper airway had developed. A restrictive fluid regimen was instituted and there was gradual resolution of this swelling over the next 3 days. At this time, gas exchange was satisfactory and the patient was successfully extubated before being discharged to the high-dependency unit.

How is inhalational injury managed on the ICU?Read More »

Pneumococcal Sepsis

An elderly man with a background of ischaemic heart disease, severe aortic stenosis and type 2 diabetes mellitus presented following recent travel from Hong Kong with shortness of breath and hypoxia. A chest X-ray confirmed left lower lobe consolidation (CRP 502, WCC 22) and he was commenced on broad spectrum antibiotics (Tazocin and Clarithromycin). Over the following 12 hours he deteriorated on the ward, with worsening hypoxia, hypotension and anuria.

He required emergency admission to intensive care for intubation and ventilation, and required inotropic support. He developed a severe metabolic acidosis and rising lactate, for which  haemofiltration was commenced. Vasopressin was added, followed by dobutamine, and hydrocortisone started for inotrope resistant hypotension. He remained ventilated on 100% oxygen, with high pressure support. He had a positive pneumococcal antigen, and high dose benzylpenicillin was added to his antibiotic regime, along with Oseltamivir (Tamiflu). Despite 12 hours of intensive therapy his acidosis worsened and he failed to respond to increasing doses of inotropic support, dying 30 hours after presentation to hospital.

What are the clinical features of pneumococcal sepsis?Read More »

High Frequency Oscillatory Ventilation in ARDS

High Frequency Oscillatory Ventilation in ARDS

A 45 year old female presented to A&E with a 5 day history of worsening SOB, cough productive of green sputum, lethargy, anorexia, fever and rigors. She had no co- morbidities and was active and independent with a good exercise tolerance. On examination she looked unwell, clammy and drowsy. Her respiratory rate was 35 breaths per minute and SpO2 of 84% on 15 Litres of oxygen via a non-rebreathing mask. Her blood pressure was 88/40 mmHg with a heart rate of 140 per minute despite having received 3 litres of fluid. Arterial blood gas showed PaO2 6.0kPa, pH 7.28, PaCO2 7.1 kPa, Bicarbonate 14 mmol/l, BE -11 and Lactate 8.6 mmol/l. Chest radiograph demonstrated significant bilateral consolidation with infiltrates consistent with ARDS. PaO2:FiO2 was calculated as 15 indicating severe ARDS presumed secondary to CAP.

She was managed as per sepsis guidelines. Oxygen therapy was continued and CPAP was initiated due to the hypoxia whilst an ICU bed was being prepared for admission. Noradrenaline was commenced at 0.2mcg/kg/min which continued to increase. Repeat arterial blood gases confirmed worsening type 2 respiratory failure and the patient was clinically exhausted. A modified rapid sequence induction was performed and IPPV commenced. Her oxygenation remained a problem and despite a FiO2 of 1.0 and PEEP of 20 his SpO2 remained 85% and PaO2 6kPa. The patients’ sedation was deepened and muscle relaxant administered. Lung protective ventilation was continued however arterial blood gases continued to worsen. The decision was made to convert the patient from conventional ventilation (CV) to High-Frequency Oscillator Ventilation (HFOV). The initial ABGs after an hour of HFOV showed an improvement as did subsequent numbers. This mode of ventilation was continued for a further 48 hours and then converted to CV. Gas exchange continued to improve. Over the course of the following 4 weeks the patient had a tracheostomy performed to aid weaning. She subsequently developed a Ventilator Associated Pneumonia and worsening ARDS required a further period of HFOV. Improvement continued and the patient was successfully decannulated and discharged from ICU.

What is the evidence base for high frequency oscillatory ventilation in ARDS?

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Tracheostomy in the Intensive Care Unit

Tracheostomy in the Intensive Care Unit

A 47-year-old male was admitted to the intensive care unit (ICU) following a high-speed motorcycle accident. He had a number of injuries including bilateral pneumothoraces, multiple spinal fractures, an open-book pelvis fracture, and a brachial plexus injury. Bilateral chest drains were inserted and external fixation of the pelvis was performed. The patient was extubated eventually at day 15 but required reintubation within 12 hours because of a poor cough and sputum retention 

What are the indications for a tracheostomy and when shout it be considered?

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ECMO for Respiratory Failure

ECMO for Respiratory Failure

A 40 year old lady was admitted under the medical team with pneumonia. She was normally well with no history of respiratory illnesses. On day two of her hospital admission she became more hypoxic necessitating continuous-positive-airway-pressure. Her condition rapidly worsened and her chest x-ray showed diffuse bilateral infiltrates. An echocardiogram demonstrated normal systolic function. She was intubated and ventilated. Despite sedation, ARDSnet ventilation, paralysis and then proning her, she remained severely hypoxaemic. A therapeutic bronchoscopy was performed prior to proning but did not improve her condition.

Should she be referred for consideration of ECMO and was is this evidence to support it’s use?

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Use of PEEP in ARDS

Use of PEEP in ARDS

A young woman was admitted with respiratory failure requiring invasive ventilation. She had bilateral lobar consolidation and positive urinary pneumococcal antigen. She was ventilated with protective lung strategies but required FiO2 of between 0.8-1.0. A PEEP of 18 was set. She was ventilated for over 2 weeks, and was tracheostomised but was discharged from the ICU after 3 weeks.

How is PEEP utilised in the ventilatory strategies in the management of Adult Respiratory Distress Syndrome?Read More »

Proning for Refractory Hypoxaemia

Proning for Refractory Hypoxaemia

A 60 yr old woman was admitted to the ICU with a severe community acquired pneumonia and septic shock. She was invasively ventilated with a lung protective strategy, optimised PEEP and recruitment manouvres as needed. Her refractory hypoxia persisted and so she was probed for 16 hours a day for the first 5 days of her admission. She made slow but steady improvements and was discharged from the ICU 10 days later.

What is the current evidence for proning as a rescue therapy for refractory hypoxia?Read More »