Ventilation and arterial oxygenation during thoracic surgery

How David Hatch became a professor of pediatric anesthesia

This is an account of an interview with David John Hatch who was one of the first Professors of Pediatric Anesthesia in the world. He began his anesthesia career as a medical student administering chloroform and ended it 40 years later as a Consultant at Great Ormond Street Hospital where he developed and led a world renowned research team measuring and assessing lung function in infants and children. These productive years earned him his chair at the Institute of Child Health in London (part of University College London) funded by Portex (currently, a branch of Smiths Medical). His academic achievements include over 110 journal publications, two textbooks and having many honors and awards. Yet he does not think of himself as an academic. In his words "I wanted to be a hard working clinician with an interest in research, and not just academic".

Impact of Acute Pain and Its Management for Thoracic Surgical Patients

Perioperative analgesia for thoracotomy has evolved in concert with increasing knowledge of the impact of pain on recovery, the origin of this pain, and new methods for treating it. Thoracic surgery is one of the few areas where there is more general agreement between surgeons and anesthesiologists as to the importance of aggressive pain management, often with an indwelling epidural catheter left in place until after thoracostomy tube removal. The reasons for this agreement is that it has become increasingly clear to both specialties that pain puts patients with decreased pulmonary reserve who undergo thoracotomy at greater risk for morbidity. Future studies need to examine drugs or drug combinations that can lead to further reductions in the often intense pain that patients receiving aggressive epidural analgesia still experience. Studies directed at finding interventions capable of reducing the rate of long-term postthoracotomy pain still need to be performed.

Cardiopulmonary effects of thoracoscopy in anesthetized normal dogs

OBJECTIVE

To evaluate the effect of an open-chest condition on oxygen delivery in anesthetized dogs.

STUDY DESIGN

Prospective, controlled experimental study.

ANIMALS

Eight clinically normal adult Walker Hound dogs weighing 25.6-29.2 kg.

METHODS

Eight anesthetized dogs underwent an open-chest operation after the insertion of thoracoscopy cannulae in the lateral chest walls. A Swan Ganz catheter was used to both measure hemodynamic parameters and obtain mixed venous blood samples for blood gas analysis. A dorsal pedal catheter was placed to both measure arterial blood pressure and obtain blood samples for blood gas analysis. Oxygen delivery index and oxygen extraction ratio were calculated. A randomized block anova for repeated measures was used to evaluate the effect of the treatment on hemodynamic and pulmonary parameters.

RESULTS

Creation of an open chest did not significantly affect oxygen delivery index (DO(2)I; p = 0.545). It induced a significant decrease in arterial oxygen partial pressure (PaO(2); p = 0.018) and arterial oxygen content (CaO(2); p = 0.025). It induced a significant increase in shunt fraction (p = 0.023), physiologic dead space (p = 0.015), and alveolar-arterial oxygen difference (p = 0.019). Arterial partial pressure of carbon dioxide (PaCO(2); p = 0.766) and arterial hemoglobin oxygen saturation (SaO(2); p = 0.178) were not significantly affected. Diastolic (DPAP; p = 0.050) and mean (MPAP; p = 0.033) pulmonary arterial pressures were significantly increased by opening the chest. Other hemodynamic parameters were not significantly affected.

CONCLUSIONS

Opening the thoracic cavity is not detrimental to hemodynamic function and oxygen delivery in normal dogs, although impaired gas exchange does occur.

CLINICAL RELEVANCE

Close monitoring of patients is recommended during open-chest thoracoscopy as adverse effects on gas exchange can contribute to hypoxemia.