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Файл:Ординатура / Хирургия / Библиотека им академика М.И. Перельмана / Книга_1047_Библиотеки_им_академика_М_И_Перельмана.pdf
Biomaterials forInguinal Hernia
Repair
RolfUlrichHartung
5
5.1 Introduction
Biomaterial has been used for hernia repair since
the beginning of hernia treatment. The idea to
implant a material with high biocompatibility
was already in the mind of surgeons since
Billroth: “If we could articially produce tissues
of the density and toughness of the fascia and
tendon, the secret of radical cure of hernia can be
discovered”. Injection of gold particles and transplantation of autografts such as the lata fascia and
dura patches have been used to deal with the
defect in the abdominal wall. Pre-fabricated prosthetics made from tantalum gauze and silvercoated wire meshes were abandoned due to high
complication rates. Francis Usher implanted the
rst synthetic mesh made of polypropylene and
published his rst experimental series of hernia
repairs with Marlex mesh in 1959 [1]. Since then
the development of meshes has exploded and
resulted in biophysical and clinical research in
order to nd the ideal mesh. Today more than 500
different meshes are on the market offering
meshes of different material, size, composition,
coating, density and weight, pore-size, structure,
exibility, tensile strength and durability, preformed anatomical shape, self-xing surface and
visibility in imaging techniques. The tremendous
R. U. Hartung (*)
Medical Director, Mediclinic City Hospital—Dubai
Healthcare City, Dubai, UAE
choices challenge surgeons and patients on which
mesh to choose for the repair of an individual
hernia. Detailed knowledge of available biomaterials became therefore a necessary requirement
for every hernia surgeon.
5.2 Biomaterial
andBiocompatibility
ofMeshes forHernia Repair
A biomaterial is either a natural or a synthetic or
a combined material that is suitable for introduction into living tissue especially as a part of a
medical device that treats, augments, or replaces
any tissue, organ, or function of the body; especially, material suitable for use in prostheses that
will be in contact with living tissue [2]. Synthetic
material might be any material including mesh,
patch, sutures, staples, glue, plastic and metal.
Transplanted material can be an autograft,
allograft or xenograft. Modern medical devices
and prostheses are often made of more than one
material alone. Although biomaterials have been
used for hernia repair since the beginning of surgery, the science of biomaterials is less than
60years old. The commonly used biomaterial for
inguinal hernia repair is a mesh. The material and
characteristics of the prosthetic mesh used determine integration, durability, functionality, incorporation and comfort.
© Springer Nature India Private Limited 2020
P. Chowbey, D. Lomanto (eds.), Techniques of Abdominal Wall Hernia Repair,
https://doi.org/10.1007/978-81-322-3944-4_5
77
78
R. U. Hartung
Biocompatibility is related to the behavior of
biomaterials in various contexts. The term refers
to the ability of a material to perform with an
appropriate host response in a specic situation
[3]. As modern medical devices and prostheses
are often made of more than one material it might
not always be sufcient to talk about the biocompatibility of one specic material alone. The biocompatibility of a long-term implantable medical
device (non-absorbable mesh) refers to the ability
of the device to perform its intended function,
with the desired degree of incorporation in the
host, without eliciting any undesirable local or
systemic effects in that host. The biocompatibility of a scaffold or matrix for a tissue-engineering
product (biologic mesh) refers to the ability to
perform as a substrate that will support the appropriate cellular activity, including the facilitation
of molecular and mechanical signaling systems,
in order to optimize tissue regeneration, without
eliciting any undesirable effects in those cells, or
inducing any undesirable local or systemic
responses in the eventual host.
5.3 Foreign Body Reaction
Any biomaterial will trigger a foreign body reaction starting at the very moment of its introduction into the host [4]. Proteins will adhere to the
prosthetic material only seconds after its implantation, followed by the invasion of platelets
releasing a variety of cytokines that will attract
white blood cells, macrophages and broblasts
[5, 6]. Within hours the implant will be covered
by an inammatory inltrate and broblasts,
leading to the formation of a brotic capsule
around each and every lament or part of the
prosthetic implant. New vessels will invade
7–14 days after the onset of the reaction thus
forming a foreign body granuloma. Different biomaterials have more or less accentuated foreign
body reactions. Thicker the granuloma grows
over each lament more likely it will cause
excessive scar formation and the risk of bridging
from one lament to the next thus transforming
the exible mesh into a stiff scar and nally a
solid plate. The functionality and biophysical
outcome of the prosthetic implant depend in
major parts on the degree of this foreign reaction.
Excessive scar formation and shrinkage of the
prosthetic implant are the main reasons for a poor
outcome after surgery possibly causing recurrence, discomfort and pain.
5.4 The Material
Different biomaterials have been developed for
the construction of meshes; synthetic nonabsorbable material such as polypropylene being
the most commonly used substance.
Polyvinylidene uoride (PVDF), polyester
(PET), polyamide (nylon) and polytetrauoroethylene (PTFE) are further synthetics used as
either patches or knitted laments for the production of non-absorbable meshes [7–9]. Polyglactin
910 and polyglycolic acid are commonly used for
absorbable implants (Table 5.1). Composite
meshes are fabricated out of different materials
most commonly with a permanent and an absorbable component. Biologic implants have been
developed for the production of scaffolds made
from human, porcine or bovine origin with the
aim to address the problem of chronic inammation and foreign body reaction. The donor tissue
is processed to acellular, porous matrix scaffolds
of collagen and elastin. The porous structure
allows cells to enter the mesh and to adhere. A
process of degradation of the biologic mesh and
regeneration of the collagen scaffold will lead to
a replacement of the mesh by host tissue
(Table 5.2). Surgeons hoped that there will be
less risk of bacterial invasion of the implant leading to the nal necessity of explantation of the
biomaterial as the scaffold will disappear by
time.
Once the mesh is knitted or woven it can be
coated to avoid adhesions, minimize the risk of
infection or reduce the foreign body reaction.
Different materials will shrink more or less once
implanted, polypropylene having the highest
shrinkage rate [7]. The material is either hydrophobic (polypropylene) or hydrophilic (polyester),
the latter being less durable as hydrolysis can
cause degradation of the laments. PTFE is com-
5 Biomaterials forInguinal Hernia Repair
79
Bard Polypropylene Monolament Small Heavy No
Brand name Company Material Structure Pore size Weight Absorbable
3DMax Bard Polypropylene Monolament/3D Small Heavy No
3D Max Light Bard Polypropylene Monolament/3D Large Light No
Dexon Syneture Polyglycolic acid Multilament Medium Medium Yes, entirely 60–90days
Dynamesh Endolap 3D FEG PVDF Monolament/3D Large Light No
Goretex Dualmesh Gore ePTFE Composite Small Heavy No
Table 5.1 Examples of synthetic meshes used for inguinal hernia repair including absorbable meshes
Marlex
Medtronic/Covidien Polyester Multilament Large Light No
(historic)
Optilene B.Braun Polypropylene Monolament Large Light No
Parietex
Hydrophilic
Parietex Lightweight Medtronic/Covidien Polyester Monolament Large Light No
ProGrip Medtronic/Covidien PET/PLA microgrips Monolament Large Light Partially, PLA 18months
Prolene Ethicon J&J Polypropylene Monolament Medium Heavy No
Ultrapro Advanced Ethicon J&J Polypropylene/polyglecapron Monolament Large Light Partially
Versatex Medtronic/Covidien Polyester Monolament Large Light No
Vicryl Ethicon J&J Polyglactin 910 Monolament Small Medium Yes, entirely 60–90days
80
Table 5.2 List of biologic meshes
Brand name Company Type Origin Cross-linked Sterilized
Alloderm LifeCell Dermis Human No No
Allomax CR Bard Dermis Human No Ye s
Collamend CR Bard Dermis Porcine Ye s Yes
Flex HD MTF Dermis Human No No
Periguard Synovis Pericardium Bovine Yes Yes
Permacol Covidien Dermis Porcine Ye s Yes
Strattice LifeCell Dermis Porcine No Ye s
Surgimend TEI Dermis Bovine No Yes
Surgisis Cook Intestine Porcine No Yes
Tutopatch Tutogen Pericardium Bovine No Yes
Veritas Synovis Pericardium Bovine No Ye s
XenMatrix CR Bard Dermis Porcine No Ye s
BioA WL Gore Synthetic absorbable Synthetic N/A Yes
TIGR Novus Scientic Synthetic absorbable Synthetic N/A Yes
R. U. Hartung
pletely inert and will be rather incapsulated than
integrated. Not only the material itself matters
when it comes to durability and risk of infection
but also the characteristics of the mesh, how it is
knitted or woven, whether mono- or polylaments
are used. Accordingly some meshes can be cut into
shape while others cannot be. Last but not least,
the production of the raw material itself matters.
Not every polypropylene mesh has the same characteristics in density, weight and porosity thus
inuencing the biocompatibility and performance
in the individual host. The mechanical strength
and density of meshes have been thoroughly investigated in experimental studies to determine
weight and strength of reduced material, the ideal
pore size and consequently the exibility and
shrinkage rate [10]. Light-weight meshes have a
weight of around 30 g/m
2
while heavy meshes
weigh up to 100g/m2. The effective difference for
a 10×15cm mesh is 1g (heavy weight 1.5g versus light weight 0.5g). Large pores measure more
than 1 mm (1–3 mm). Pores less than 75 μm in
size will not allow macrophages to enter and
hereby signicantly decrease the resistance to
infection (PTFE). Even the lightest meshes available on the market withstand twice the maximum
intra-abdominal pressure peeks of 170mmHg during coughing and jumping. Different coatings
shall not only minimize the tendency of adhesions
but also prevent infection and possibly make
meshes visible by imaging such as ultrasound and
MRI investigations. Experimental and clinical
studies with iron nanoparticle coating have
resulted in information about displacement and
long-term shrinkage rates of different mesh types.
3D meshes aim to preform the anatomical shape of
the inguinal region and might allow future onsite
production of a precisely tting 3D printed mesh
for an individual patient.
5.5 The Choice ofMesh
Ideally a mesh should be chemically inert, nontoxic, non-allergenic and non-carcinogenic, sterilizable, easy to be fabricated and formed, and
easy to be handled and implanted. There should
be no or very little foreign body reaction and no
risk of adhesions. It should resist infection and
seroma formation, have a sufcient mechanical
strength and durability, and enough exibility to
allow normal body movements. The mesh should
be incorporated such as autologous tissue and
guarantee a lifelong repair of the hernia without
recurrence and pain.
However the success and long-term outcome of
an inguinal hernia repair are not only dependent on
the mesh itself but also on the condition of the individual patient, the size of the defect, the presence of
infection or contamination. Large defects will need
to be covered by larger and stronger meshes in order
to avoid mesh migration and herniation into the
defect. The discussion whether to implant a synthetic or a biologic mesh or no mesh at all in pres-
5 Biomaterials forInguinal Hernia Repair
81
ence of contamination and infection is still ongoing.
Human acellular dermal matrix (HADM) and animal skin and intestine from pigs (porcine) and cows
(bovine) are commonly used biologic materials for
hernia repair with own risks and side effects [11].
Cultural, religious and personal factors inuence
the decision on the choice of biologic meshes. All
biologic implants are considered to be temporary
scaffolds, absorbable implants aiming to improve
patients own repair mechanisms by forming durable
scars. However the knowledge about decient collagen in acquired hernias limits the expectations of
this ideal appearing concept. Furthermore the threefold higher costs of biologic meshes are not in
favour of the routine use of those implants.
When it comes to the decision about the choice
of mesh for hernia repair, the surgeon will consider
the ease of handling and xation of the implant.
Introduction and deployment have to be guaranteed
without damaging the structure or surface of the
mesh. Self-xing meshes might apparently have
less risk of displacement; however, the intracorporal handling requires more advanced skills and precision of the surgeon. Once the mesh is correctly
placed, many surgeons prefer to x the mesh at
least in one or two areas of reference, in inguinal
hernia repair typically at Cooper’s ligament. All the
available xation devices are equally made of biomaterial, permanent or absorbable, whether
sutures, tacks or glue are used. Every single component of the entire biomaterials used during inguinal hernia repair will inuence the outcome and
possible side effects of the procedure. As in all different open and laparoscopic surgical techniques of
inguinal hernia repair the mesh will be placed in
the pre- or extraperitoneal space, the mesh will not
need to have an anti-adhesive coating. When it
comes to the size of the mesh 10×15cm meshes
are recommended for laparoscopic inguinal hernia
repair and larger meshes are available to ensure a
sufcient preferably 5cm overlap to all sides. Plugs
placed inside the opening are not favoured anymore. For most cases of inguinal hernia repair a
monolament synthetic mesh (polypropylene,
polyester, PVDF) with large pores and low density
will be the right choice [12, 13].
5.6 Clinical Outcome
Since the development of meshes for inguinal
hernia repair the direct suture repair techniques
have decreased signicantly. Only in pediatric
hernias the suture repair is still the method of
choice. Whether open Lichtenstein procedure is
performed or laparoscopic techniques such as
TEP and TAPP in all cases a mesh will be
implanted. Long-term studies and analysis of
hernia registries have shown that the tension
free repair with mesh resulted in lower recurrence rates and less pain after surgery in comparison to direct suture repair techniques such
as Shouldice and Bassini repair representing
less than 10% of all inguinal hernia repairs
today. All international guidelines have therefore recommended the use of mesh for inguinal
hernia repair over the direct suture repair based
on level 1A evidence that mesh repair results in
less recurrences when compared to techniques
without the use of mesh. With level 1B evidence
material-reduced meshes with large pores are
favoured for the open inguinal hernia repair due
to less long-term discomfort and foreign body
sensation [14].
5.7 Summary
Nowadays the commonly used biomaterial for
inguinal hernia repair is a mesh. Ninety percent
of all inguinal hernia repairs are performed by
implantation of synthetic meshes. The advantage
of a tension-free repair over the suture repair with
tension has resulted in lower recurrence rates and
less pain. All international guidelines recommend the use of synthetic non-absorbable or
composite mesh with a non-absorbable component based on Level 1A evidence. The development of material-reduced lightweight meshes
with large pores has contributed to better longterm results with less discomfort for the patient.
The implantation of biological meshes has not
resulted in better outcomes but contributed to
higher costs only.
82
R. U. Hartung
References
1. Skandalakis JE, Colborn GL, Skandalakis LJ,
McClusky DA.Historic aspects of groin hernia repair.
In: Fitzgibbons RJ, Greenburg AG, editors. Nyhus
and Condon’s hernia. 5th ed. Philadelphia: Lippincott,
Williams & Wilkins; 2002. p.39.
2. Williams DF, editor. Denitions in biomateri-
als, Proceedings of a Consensus Conference of the
European Society for Biomaterials. Amsterdam:
Elsevier; 2004.
3. Williams DF.On the mechanisms of biocompatibility.
Biomaterials. 2008;29(20):2941–53.
4. Klosterhalfen B, Hermanns B, Rosch R. Biological
response to mesh. Eur Surg. 2003;35:16–20.
5. Pereira-Lucena CG, Artigiani-Neto R, Lopes-Filho
GJ, Frazao CV, Goldenberg A, Matos D, et al.
Experimental study comparing meshes made of
polypropylene, polypropylene + polyglactin and
polypropylene + titanium: inammatory cytokines,
histological changes and morphometric analysis of
collagen. Hernia. 2010;14:299–304.
6. Klosterhalfen B, Junge K, Klinge U.The lightweight
and large porous mesh concept for hernia repair.
Expert Rev Med Devices. 2005;2:103–17.
7. Klosterhalfen B, Klinge U, Schumpelick V.Polymers
in hernia repair-common polyester vs. polypropylene
surgical meshes. J Mat Sci. 2000;35:4769–76.
8. Deeken CR, Abdo MS, Frisella MM, Matthews
BD. Physicomechanical evaluation of polypropylene,
polyester, and polytetrauoroethylene meshes for inguinal hernia repair. J Am Coll Surg. 2011;212:68–79.
9. Gonzalez R, Ramshaw BJ. Comparison of tissue
integration between polyester and polypropylene
prostheses in the preperitoneal space. Am Surg.
2003;69:471–6, discussion 476–7.
10. Agarwal BB, Agarwal KA, Mahajan KC.Prospective
double-blind randomized controlled study comparing
heavy- and lightweight polypropylene mesh in totally
extraperitoneal repair of inguinal hernia: early results.
Surg Endosc. 2009;23:242–7.
11. Harth KC, Rosen MJ. Major complications associated with xenograft biologic mesh implantation in abdominal wall reconstruction. Surg Innov.
2009;16(4):324–9.
12. Bilsel Y, Abci I. The search for ideal hernia
repair; mesh, materials and types. Int J Surg.
2012;10(6):317–21.
13. Brown CN, Finch JG.Which mesh for hernia repair.
Ann R Coll Surg Engl. 2010;92(4):272–8.
14. Simons MP, Aufenacker T, Bay-Nielsen M, Bouillot
JL, Campanelli G, Conze J, De Lange D, Fortelny R,
Heikkinen T, Kingsnorth A, Kukleta J, Morales-Conde
S, Nordin P, Schumpelick V, Smedberg S, Smietanski
M, Weber G, Miserez M. European Hernia Society
guidelines on the treatment of inguinal hernia in adult
patients. Hernia. 2009;13(4):343–403.
Anaesthesia forLaparoscopic
Abdominal Wall Hernia Repair
AparnaSinha andLakshmiJayaraman
6
6.1 Anaesthesia for Laparoscopic Abdominal Wall Hernia Repair
Abdominal wall hernia is a very common surgical
problem. In the last two decades laparoscopic/
endoscopic approach has become the preferred
surgical option for management of the same.
Laparoscopic techniques have become popular
due to the major advantages they offer. These
include minimal incision size, minimal postoperative discomfort, earlier discharge readiness, lesser
postoperative pain, enhanced recovery and lesser
incidence of postoperative wound infections.
These factors further contribute to lesser hospital
stay and minimal perioperative morbidity.
The advancements in the surgical techniques
of endohernia repair have led to innovations and
renement in the anaesthetic management of the
same. The repair endohernia is one of the most
commonly performed surgeries today.
The endoscopic hernia repair includes management of myriad of conditions including,
totally extra-peritoneal (TEP), transabdominal
preperitoneal (TAPP) repair of inguinal hernia
and intraperitoneal onlay mesh (IPOM) repair of
A. Sinha (*) · L. Jayaraman
Institute of Minimal Access, Metabolic and Bariatric
Surgery, Max Super Speciality Hospital,
New Delhi, India
ventral hernia. Laparoscopy allows identication
of contralateral hernia and its safe repair by
avoiding cord structures and regional nerves.
• Totally extra-peritoneal repair (TEP): In this
technique there is the placement of mesh into
the preperitoneal space.
• Trans-abdominal (TAPP): Placement of mesh
over peritoneal defects in the abdominal
wall.
• Laparoscopic intraperitoneal onlay mesh
(IPOM).
The TEP is preferred in simple unilateral,
bilateral or recurrent hernia, whereas TAPP
allows the surgeon to approach large scrotal,
incarcerated and complex recurrent hernias, with
greater ease. This also allows a concomitant diagnostic laparoscopy. However, laparoscopy is not
without its associated problems and complications. Moreover, based on the type of hernia the
repair may involve placing the patient in extremes
of position, which brings its own challenges.
Athorough understanding of anesthetic implications of endoscopic hernia repair is mandatory
for safe execution of anaesthesia.
Thorough preoperative evaluation, prepara-
tion, protocols to troubleshoot consequences of
raised intra-abdominal pressure (IAP) and effective pain management are keys to safe anaesthesia practice.
© Springer Nature India Private Limited 2020
P. Chowbey, D. Lomanto (eds.), Techniques of Abdominal Wall Hernia Repair,
https://doi.org/10.1007/978-81-322-3944-4_6
83
84
A. Sinha and L. Jayaraman
6.1.1 Pathophysiological Changes During Endoscopic Hernia Repair
Though laparoscopy offers advantages to both
patients and surgeons, it can impose signicant
alteration in respiratory and cardiovascular
homeostasis and should never be regarded as
another minor intervention. During laparoscopic
procedures, the major barriers to normal homeostasis are patient positioning, introduction of several liters of gas (CO2) into the extraperitoneal
space (TEP) or abdominal cavity (as in TAPP and
IPOM) to produce carboperitoneum and the
raised intra-abdominal pressure (IAP) that ensues
from it. All these produce several pathophysiological changes, some of which are unique to
laparoscopy (Tables 6.1 and 6.2).
6.1.2 Positioning andAssociated
Pathophysiologic Problems
Initial introduction of the Verees needle may
require the patient to be placed in the
Trendelenburg position (15°–20°) for most her-
Table 6.1 Hemodynamic effects of carboperitoneum
• Hypertension, tachycardia: Increased myocardial
oxygen demand
• Increased noradrenaline levels: Increased SVR (and
decreased Q)
• Hypercarbia and acidosis
• Reduced urine output and increased plasma renin
activity (PRA)
– Increased intra-abdominal pressure (IAP)
– Local compression of renal vessels
• Intra-abdominal distension: Decrease in pulmonary
dynamic compliance
• Low compliance plus increased minute volume of
ventilation: Raised peak airway pressures
Table 6.2 Respiratory effects in endo-hernia repair
• Carboperitoneum ventilatory and respiratory
changes
• Thoracopulmonary compliance ↓ (30–50%)
• PaCO
• PEtCO
• Increase PEtCO
15–20% ↓ (CO2 absorption from peritoneal
2
cavity)
plateaus in 30min
2
subcutaneous emphysema
>25% in<30min suggestive of
2
nia repairs to allow introduction of carbon
dioxide.
This displaces the abdominal viscera and thus
prevents visceral injury during trocar insertion. It
increases venous return (VR), right atrial pressure (RAP), central blood volume and cardiac
output [1, 2]. Respiratory mechanics are also
affected, due to cephalad displacement of diaphragm [1–3].
This augments development of atelectasis
especially in obese, elderly and debilitated
patients. In ASA I and II patients no major
changes are seen [4].
The same IPOM procedure’s reverse
Trendelenburg position (20°–30°) is adopted,
this improves diaphragmatic functions and is
more favourable for respiration; however, compromises on the central blood volume and cardiac output [5]. The pathophysiological
changes may vary in extra-peritoneal repairs
(Fig.6.1).
The steepness of the tilt and duration of surgery ultimately decide the magnitude of these
changes. Deleterious effects can occur in patients
with cardiovascular dysfunction [4]. The reduced
pressures due to Trendelenburg position reduce
blood loss from the pelvic viscera, but increase
the risk of gas embolism [4, 6].
Nerve injuries have been potential complications of head low position. Caution must be exercised to prevent them particularly the brachial
plexus injuries. This can be prevented by placing
the arms of the patient by the side and applying
shoulder supports (Figs.6.2 and 6.3).
6.1.3 Insuation ofExogenous Gas
Choice of an optimal insufating gas to create
pneumoperitoneum remains a signicant issue in
laparoscopy. Various gasses have been used for
creating pneumo-peritonium in laparoscopy
including oxygen, air, nitrous oxide (N2O), nitrogen (N2), carbon di oxide (CO2), Argon and
Helium. Carbon dioxide (CO2) has remained the
insufation gas of choice. It is relatively inert,
readily absorbed, and does not support
combustion and hence permits the use of electrocautery [7].
6 Anaesthesia forLaparoscopic Abdominal Wall Hernia Repair
85
Fig. 6.1 Effects of
position and
carboperitoneum
Circulation:
≠ Stroke Volume
Circulation–
≠ Venous Return
CO
insufflation (intraperitoneal/extraperitoneal)
2
≠ Contractility, dysrhythmias,
Venous gas embolism
(cephalad displacement of diaphragm)
Increased intra-abdominal pressure (IAP)
≠ Systemic Vascular Resistance
Reverse Trendelenburg Position
Circulation–
Ø Venous Return
Ø Afterload
Trendelenburg Position
Respiration:
≠ Mean Arterial Blood Presssure Ø Cardiac Output
Respiration–
Ø Lung Volumes,
≠ Work of Breathing
Respiration–Hypercarbia
≠ Lung volumes improve
Ø Work of breathing
Fig. 6.2 Shows position of OT table, monitors and sur-
geons during TEP
Fig. 6.3 Patient in Trendelenburg position, both arms by
the side and shoulder supports in place to prevent sliding
of patient during extremes of position
86
A. Sinha and L. Jayaraman
It is very highly soluble in blood (solubility
coefcient=0.49) at 37°C and has a linear and
steep dissociation curve. If PaCO2 ranges between
45 and 50mmHg, the absorption of CO2 during
carboperitoneum has minimal impact on hemodynamics. Whereas, if the PaCO2 ranges between
51 and 60mmHg, it causes sympathetic response
and alters the cardiovascular response. The elevation in catecholamines and the pathophysiological changes of laparoscopy have been largely
attributed to the increase in IAP rather than rise
inCO2.
In healthy patients (ASA I and II), the rise in
pCO2 and the resulting acidemia is clinically
insignicant because of the buffering systems
and rapid elimination by lungs. The rise in CO2
elimination is not due to hyper metabolism, as
suggested by increase in CO2 elimination but
unchanged O2 consumption. The initial rise in
intracranial pressure is due to mechanical effects
of raised IAP, whereas the delayed rise seen in
prolonged surgeries is due to vasodilatation
induced by hypercapnia. Caution needs to be
exercised in patients of chronic obstructive pulmonary disease, who have elevated baseline
PaCO2. These patients may show signs and
symptoms of raised CSF pressure in the form of
headache, blurring of vision and papilledema.
Central pipeline or cylinders may be used to
supply carbon dioxide.
N2O is not a part of acid-base buffer system
and has only weak hemodynamic effects. This is
not a preferred agent due to its property to support combustion. Nitrous oxide (N
O) is better as
2
an insufating gas when the procedure is to be
conducted under regional anaesthesia, since it
produces minimal irritation of the peritoneal cavity [8]. However; caution needs to be exercised
with use of cautery.
Helium insufation is a reasonable alternative
in patients at risk for CO2 retention or has signicant cardiopulmonary compromise [9]. Its low
water and plasma solubility makes it unsuitable
in the event of gas embolism.
Argon is yet another alternative, which is
odorless, colorless gas, with no effect on acidbase status. It has poor solubility in blood makes
it dangerous in case embolism happens.
Table 6.3 Properties of an ideal insufating gas
• Readily available
• Nontoxic and colorless
• Relatively inert
• Non-combustible
• Inexpensive
• High Ostwald blood/gas partition coefcient (0.48)
(readily soluble and easily ventilated through lungs)
Carbon dioxide possesses most of the
desirable characteristics hence the term carboperitoneum is used synonymously with pneumoperitoneum [8–10] (Table6.3).
6.1.3.1 Carboperitoneum
andIncreased Intra-abdominal
Pressure
With the rise in IAP, the perfusion of viscera particularly that of the renal and hepatic perfusion is
signicantly compromised and is a major concern in patients with existing disease. Duration of
carboperitoneum can have signicant implications on the outcomes.
The renal effects of carboperitoneum are recognized as independent cause of acute kidney
injury. The mechanism for this is secondary to
the combined effect of reduced renal afferent
ow due to impaired cardiac output and reduced
efferent ow in view of raised renal venous
pressure.
Increase in the intra-abdominal pressure contributes to circulatory instability during laparoscopy [11]. Since TEP is performed without
establishing carboperitoneum, the adverse effects
of a raised IAP are not seen, unlike in TAPP and
IPOM, which necessitate the establishment of
carboperitoneum [12].
Since the resorptive surface area is much
larger in extra-peritoneal repairs, the rise in
EtCO
is much greater [10, 13, 14]. The absorp-
2
tion of CO2 steadily increases in TEP repair,
while it tends to reach a plateau in TAPP [15].
Disruption of the microvascular and lymphatic
channels in TEP, facilitates direct intravascular
uptake of CO2 [16].
The absorption of gases from the peritoneum
is less at the commonly used pressure of
14–18 mmHg (for TAPP, IPOM repair) and