Laparoscopy is an emerging modality in the growing field of veterinary minimally invasive surgery Although laparoscopic procedures have been greeted enthusiastically by some surgeons as a way to reduce postoperative pain and hasten return to normal activity postoperatively, few studies1–5 have been performed to evaluate the physiologic response to pneumoperitoneum in small animals.
Use of laparoscopy in cats was first reported in 1977,6 yet few reports7–11 of laparoscopic surgery in cats have been published since that time. Intentional induction of pneumoperitoneum is integral to most laparoscopic procedures, and the physiologic effects of pneumoperitoneum have been described in dogs.1–5 As IAP increases, an initial increase in cardiac output can occur as blood from splanchnic circulation is pushed into systemic venous circulation and returned to the heart.2 However, an overall decrease in cardiac output is reported to develop during pneumoperitoneum as pressure on thin-walled vascular structures in the abdomen compromises venous return and a general increase in systemic vascular resistance occurs.5 This is particularly true at high IAPs.1,2 A study5 in dogs also revealed that at pressures up to 15 mm Hg, no clinically relevant reduction in cardiac output occurs.5 From consideration of these data has come the general recommendation that IAPs up to 15 mm Hg are considered safe in dogs. No such studies have been performed in cats, and species-specific guidelines are needed for clinicians wishing to perform laparoscopic procedures in feline patients.
The volume of working space created by intentionally induced pneumoperitoneum is largely dependent on the degree of abdominal insufflation. To the authors’ knowledge, the relationship between working space and IAP in dogs or cats has not been scientifically established, although anecdote suggests that in cats, even at relatively low IAPs (approx 4 mm Hg), adequate working space can be created to complete some procedures.8 The reason for this phenomenon is unknown, but a hypothesis is that the considerable distensibility of the abdominal wall in cats might allow low-pressure pneumoperitoneum to produce a greater volume of working space for any given IAP relative to some other species.8 Elucidation of the actual relationship between working space and IAP in cats would allow guidelines to be created for surgeons wishing to incorporate laparoscopy into their practices. Indeed, if low-pressure pneumoperitoneum can be routinely used, then its use may decrease the incidence of cardiorespiratory compromise during laparoscopic procedures. Because pneumoperitoneum has been suggested to be one of the principal causes of surgical stress during laparoscopy, high-pressure pneumoperitoneum may be particularly contraindicated in geriatric cats or those with preexisting cardiorespiratory disease that may not tolerate high IAP as well as healthy cats.12
The purpose of the study reported here was to evaluate the cardiorespiratory response in healthy adult cats during surgical induction of pneumoperitoneum at various IAPs and to quantify the working space provided by pneumoperitoneum at those IAPs. Our hypotheses were that pneumoperitoneum would be well tolerated by the cats at all IAPs and that no significant difference in volume of working space would exist between low and high pressure pneumoperitoneum.
Arterial oxygen content
Oxygen delivery rate
Mean arterial blood pressure
Partial pressure of arterial carbon dioxide
Partial pressure of arterial oxygen
Pulmonary arterial occlusion pressure
Pulmonary arterial pressure
Stroke volume index
Systemic vascular resistance index
Oxygen consumption rate
Atropine sulphate, West-ward Corp, Eatonton, NJ.
Buprenorphine hydrochloride, Reckitt Benckiser Pharmaceuticals Inc, Richmond, Va.
Propofol, Abbott Animal Health, Chicago, Ill.
Piramal Healthcare Ltd, Andrah Pradesh, India.
Arrow AK-04650-E, Teleflex Medical, Durham, NC.
Arrow CP-07511-P, Teleflex Mecical, Durham, NC.
Arrow AI-07044, Teleflex Medical, Durham, NC.
Ternamian Endotip cannula, Karl Storz Veterinary Endoscopy, Goleta, Calif.
Endoflator, Karl Storz Veterinary Endoscopy, Goleta, Calif.
Hopkins II, Karl Storz Veterinary Endoscopy, Goleta, Calif.
Research Randomizer, Social Psychology Network, Middletown, Conn. Available at: www.randomizer.org. Accessed Nov 14, 2011.
Datex-Ohmeda S/5 compact anesthesia monitor, GE Healthcare Technologies, Madison, Wis.
COM-1, American Edwards Laboratories, Irvine, Calif.
ABL 800, Radiometer, Copenhagen, Denmark.
Myotape, Accufitness Inc, Greenwood Village, Colo.
Intercooled Stata, version 12.1, Stata Corp, College Station, Tex.
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