Clare Savage

Postthoracotomy pain management

The following techniques appear efficacious in controlling postthoracotomy pain and reducing the amount of systemic opioids consumed: continuous intercostal blockade, paravertebral blockade, and epidural opioids and/or anesthetics. The combination of thoracic epidural opioid and local anesthetic is very effective at relieving postthoracotomy pain, however, considerable experience is required for insertion of the thoracic epidural catheter and postoperative respiratory monitoring. Intercostal and paravertebral catheters can be inserted intraoperatively under direct visualization, to reduce complications of insertion. One-time intraoperative intercostal blockade may effectively reduce postoperative pain in the first day, but is not a practical long-term method for postthoracotomy pain. The effectiveness of interpleural analgesia, even with proper technique, appears inferior to epidural and other regional techniques. We have incorporated the principles outlined in this review into our general thoracic surgery protocol, as detailed in Fig. 1. Every patient is assessed preoperatively for epidural catheter placement. Contraindications include low platelet count (< 100,000), abnormal coagulation profile, medicinal anticoagulation (aspirin and nonsteroidal anti-inflammatories are not contraindications), bony spinal abnormalities, or neurological disorders. The T5/6 interspace is our preferred level, but T10 can work well with an increased dose of bupivacaine. Upon completion of the muscle sparing, minimal-access thoracotomy, we close the wound and perform a percutaneous intercostal nerve block (two ribs above and three below the incision). We then use patient-controlled epidural analgesia, with a basal infusion of bupivacaine and hydromorphone. To supplement inadequate or nonfunctioning epidurals, intravenous patient-controlled opioids are added. When choosing an approach to postthoracotomy pain management, the thoracic surgeon and anesthesiologist must consider the following: (1) the physicians experience, familiarity and personal complication rate with specific techniques; (2) the desired extent of local and systemic pain control; (3) the presence of contraindications to specific analgesic techniques and medications; and (4) availability of appropriate facilities for patient assessment and monitoring postthoracotomy. Refinements in surgical technique including limited or muscle-sparing thoracotomy, video-assisted thoracoscopic surgery (VATS) and robotic surgery may lessen the magnitude of postthoracotomy pain. We encourage all thoracic surgeons to be knowledgeable of available techniques and maintain a protocol to generate a database for periodic assessment of safety and efficacy.

Percutaneous retrieval of chronic intravascular foreign bodies.

Abstract To evaluate the feasibility of intravascular retrieval of chronic foreign bodies, we retrospectively reviewed an 8 year experience (1993–2001) of percutaneous retrieval of chronically retained intravascular foreign bodies (n = 6). In 6 of 6 cases (4 catheter fragments, 2 guidewires), 5–90 days elapsed before retrieval via the femoral or internal jugular vein. Under fluoroscopy, we determined the foreign body’s course, position and size. A guidewire was advanced through a multipurpose catheter to the foreign body. The multipurpose catheter was replaced with a gooseneck snare catheter and the snare advanced to grasp and remove the foreign body. Percutaneous retrieval was successful in all 6 cases. One patient experienced mild hemoptysis, which resolved within 24 hr of observation. No patient experienced long-term sequelae. Given the potential life-threatening complications from intravascular foreign bodies and the low complication rate from percutaneous retrieval, we recommend extraction of the foreign body even if it is asymptomatic in the chronic setting (> 24 hr).

Hemoptysis secondary to pulmonary pseudoaneurysm 30 years after a gunshot wound

A 49-year-old man presented with intermittent hemoptysis from a traumatic pulmonary artery pseudoaneurysm 30 years following a thoracic gunshot wound. The patient was asymptomatic for 28.5 years, when he began experiencing recurrent hemoptysis, chest pain, and a cough. A left lower lobe mass on chest x-ray film was investigated with contrast-enhanced computed tomography and pulmonary angiogram confirming a 1.5-cm pseudoaneurysm. Intraluminal coil embolization was attempted, but a left lower lobectomy was ultimately necessary to treat persistent hemoptysis.

Interleukin-8, aquaporin-1, and inducible nitric oxide synthase in smoke and burn injured sheep treated with percutaneous carbon dioxide removal.

We previously showed that a percutaneous arteriovenous gas exchanger was effective in removing CO2 and reversing respiratory failure in an ovine model of adult respiratory distress syndrome (ARDS) produced by smoke inhalation and burn injury (Alpard et al., Ann Surg 230:215–224, 1999). In this study, we tested the hypothesis that arteriovenous CO2 removal (AVCO2R) lessened endogenous inflammation in the lung. Myeloperoxidase activity, aquaporin-1 (AQP-1), interleukin-8 (IL-8), and inducible nitric oxide synthase mRNAs as well as aquaporin-1, and IL-8 protein were measured in ovine lung tissue. Lung tissue was taken at 96 h (time of sacrifice) from animals with combined smoke inhalation and 40% third degree dermal burn and subsequently treated with AVCO2R or sham (ventilator alone) after onset of ARDS (PaO2:FiO2 ratio of < 200). Myeloperoxidase activity was 1.862 ± 0.302 U/mg protein in the ventilator group and 0.830 ± 0.141 in the AVCO2R plus ventilator group. AQP-1 mRNA was 140,482 ± 31,702 copies/&mgr;g total RNA in the ventilator group and 61,854 ± 22,433 copies/&mgr;g total RNA in the AVCO2R plus ventilator group (p = 0.076). mRNA for IL-8 mRNA in the ventilator alone treated animals was 74,000 ± 3,300 copies/&mgr;g total RNA compared to < 1,000 copies/&mgr;g total RNA in the ventilator plus AVCO2R group. This result was highly significant (p < 0.001) Inducible nitric oxide synthase mRNA was 7,853 ± 2,229 copies/&mgr;g total RNA for the AVCO2R group and 5,854 ± 2,070 copies/&mgr;g total RNA for the ventilator managed animals. These differences were not statistically significant (p = 0.54). Percutaneous AVCO2R produced a specific decrease in IL-8 in the smoke and burn injured animals. Furthermore, this effect was consistent with cell signaling mechanisms that increase the expression of IL-8 by cyclic stretching and the observed reduction in the number of neutrophils in the lung parenchyma. Therefore, we speculate that the mechanism by which CO2 removal exerts a beneficial effect may be due to both decreases in ventilatory requirements, with an accompanying reduction in alveolar stretching, and reduction of neutrophil numbers in lung tissue.

Low-dose versus high-dose heparinization during arteriovenous carbon dioxide removal

The purpose of this study was to compare low-dose (LD) and high-dose (HD) systemic heparinization in a prospective randomized study of arteriovenous carbon dioxide removal (AVCO2R) during acute respiratory distress syndrome, using a commercially available heparin-coated oxygenator. Adult sheep (n = 13) received an LD50 smoke inhalation and 40% TBSA third degree cutaneous flame burn injury. At 40-48 h post-injury, animals underwent cannulation of the carotid artery and jugular vein and were then randomized to HD heparin (activated clotting time, ACT > 300 s, n = 6) and LD heparin (ACT > 200 s, n = 7) and placed on AVCO2R for approximately 72 h using an oxygenator with the Trillium Bio-Passive Surface™. Mean ACTs were significantly different, as expected (HD: 446 ± 26 s, LD: 213 ± 12 s, p < 0.05). AVCO2R shunt flow averaged approximately 13% of cardiac output with mean CO2 removal similar in HD and LD, p = NS. The hematocrit, platelet count, and fibrin degradation products for the two groups were not different. No differences in thrombosis or bleeding were noted. In conclusion, LD systemic heparin (ACT < 200 s) with a heparin-coated oxygenator does not increase thrombogenicity during AVCO2R for smoke/burn-induced severe lung injury in sheep.

High-frequency percussive ventilation with systemic heparin improves short-term survival in a LD100 sheep model of acute respiratory distress syndrome

We undertook an assessment of high-frequency percussive ventilation (HFPV) and systemic heparin on survival in our LD100 sheep model of smoke/burn-induced acute respiratory distress syndrome (ARDS). This was a prospective controlled outcomes study in a large animal critical care laboratory. ARDS was induced in 13 sheep by a combination of 48 cotton smoke breaths and 40% full-thickness cutaneous burn (LD100) followed by mechanical ventilation (15 ml/kg tidal volume). After meeting ARDS criteria (PaO2/FiO2 < 200), the sheep were divided into high-frequency percussive ventilation (HFPV; n = 7) or volume-controlled mechanical ventilation (VCMV; n = 6) groups. Both groups received systemic heparin to achieve an ACT 180–300 seconds. HFPV was managed with the Volumetric Diffusive Respiration Ventilator (Percussionaire Corp., Sandpoint, ID). The VCMV group was managed with up to 10 ml/kg tidal volume. Arterial blood gases and ventilator settings were monitored every 6 hours after onset of ARDS. HFPV did not affect sheep hemodynamics. Survival 84 hours after smoke and burn injury was significantly greater in the HFPV (7/7, 100%) compared with the VCMV group (3/6, 50%, P < .05). PaCO2 was significantly greater in VCMV group at 36, 48, and 72 hours after smoke and burn injury. PaO2/FiO2 after 36 hours of smoke and burn injury in the HFPV group was improved compared with the VCMV group, but no statistical difference was found. In the VCMV group, peak airway pressure was decreased to 19.7 ± 2.2 cm H2O at 36 hours from 29 ± 2.8 at 24 hours as the tidal volume changed from 15 ml/kg to 10 ml/kg and then gradually increased to 39 ± 5.6 cm H2O at 72 hours. In the HFPV group, peak inspiratory pressure kept constant at a level of 30 cmH2O. In our smoke/burn-induced LD100 sheep model of ARDS, volume-controlled mechanical ventilation with systemic heparin achieved a 50% survival whereas HFPV with systemic heparin achieved 100% survival at 60 hours after the onset of ARDS.

Toward ambulatory arteriovenous CO2 removal: Initial studies and prototype development

Extracorporeal arteriovenous carbon dioxide removal (AVCO2R) using percutaneous cannulae and a low resistance gas exchanger achieves near total CO2 removal, allowing lung rest and potentially improving survival. AVCO2R, redesigned to allow ambulation, has potential as treatment for severe chronic obstructive pulmonary disease or rehabilitation before lung transplant. The purposes of this study were to 1) determine the optimal ambulatory access for AVCO2 removal and 2) develop a prototype Ambulatory-AVCO2R gas exchanger. Initially, reinforced Gore-Tex 6 mm (two) and 8 mm (four) grafts were anastomosed to sheep carotid arteries and jugular veins as a loop in parallel to the cranial circulation to determine blood flow capabilities. Blood flow was 100–150 ml/min with a 14 gauge dialysis needle, and transected 6 mm Gore-Tex grafts achieved 500–900 ml blood flow, whereas transected 8 mm grafts achieved up to 2000 ml/min flow. The polytetrafluoroethylene (PTFE) loops were then connected to our newly developed ultra low resistance pumpless gas exchanger for ambulatory AVCO2R. The average pressure gradient across the prototype Ambulatory-AVCO2R gas exchangers (n = 5) was 2.8 ± 0.8 mm Hg, and mean CO2 removal was 104.8 ± 14.0 ml/min, with an average blood flow of 900 ml/min. We conclude that an 8 mm Gore-Tex reinforced graft arteriovenous loop supplies ample blood flow for our new ultra low resistance Ambulatory-AVCO2R to achieve near total CO2 removal.

Thoracic imaging in the ICU: Interventional radiology

Radiology in the intensive care unit (ICU) patient is dominated by plain x-rays, with noteworthy findings prompting further imaging and possible intervention. This chapter discusses interventional and minimally invasive techniques used to treat pleural, mediastinal and pulmonary parenchymal problems commonly encountered in the ICU.

Percutaneous unknotting and retrieval of Swan-Ganz catheter

An 18-month-old boy had a Swan-Ganz catheter inserted through the right femoral vein. A chest roentgenogram after placement showed that the catheter was advanced too far and was curled with multiple loops in the right atrium. Under fluoroscopy, the catheter was pulled back into the inferior vena cava (IVC) where the multiple loops formed a knot that prevented passage beyond the IVC bifurcation (Fig A). A forceps catheter (BIOPAL 7 formable biopsy forceps; Cordis Corporation, Miami, FL) (arrows) was inserted through the contralateral femoral vein to unknot (Fig B) and remove (Fig C) the Swan-Ganz catheter. The procedure was uncomplicated, and the patient demonstrated no sequelae on follow-up. The array of tools available to the interventional radiologist including forceps, hook or straight catheter, loop snare, tip-deflecting wire, flexible-tip guidewire, and retrieval basket to facilitate in vivo reduction of catheter knots, often precluding the need for venotomy or surgical removal [1, 2]. We recommend slow withdrawal under fluoroscopy of any Swan-Ganz catheter that has multiple loops or appears knotted. If the catheter fails to unfurl or meets resistance, an interventional radiologist should be consulted while the loops are still accessible to instrumentation.

Giant left atrial intrapericardial aneurysm: noninvasive preoperative imaging.

Congenital giant intrapericardial aneurysms of the left atrium are rare. A 17-year-old boy presented with paroxysmal episodes of palpitations, chest pain, and dyspnea. A chest roentgenogram showed an enlarged left cardiac silhouette. Transthoracic echocardiography imaging showed an intrapericardial aneurysm of the left atrium. Cardiac magnetic resonance imaging confirmed the diagnosis and delineated adjacent structures to plan the surgical resection. We have found no previous reports of cases of diagnosis and preoperative assessment based solely on noninvasive imaging.